[v3,1/4] firmware: arm_scmi: Add Voltage Domain Support

Commit Message

Cristian Marussi Oct. 26, 2020, 8:31 p.m. UTC

Add SCMI Voltage Domain protocol support.

Signed-off-by: Cristian Marussi <[e-mail]>
---
v2 --> v3
- restrict segmented voltage domain descriptors to one triplet
- removed unneeded inline
- free allocated resources for invalid voltage domain
- added __must_check to info_get voltage operations
- added a few comments
- removed fixed size typing from struct voltage_info

v1 --> v2
- fix voltage levels query loop to reload full cmd description
  between iterations as reported by Etienne Carriere
- ensure rx buffer is properly sized calli scmi_reset_rx_to_maxsz
  between transfers
---
 drivers/firmware/arm_scmi/Makefile  |   2 +-
 drivers/firmware/arm_scmi/common.h  |   1 +
 drivers/firmware/arm_scmi/driver.c  |   2 +
 drivers/firmware/arm_scmi/voltage.c | 398 ++++++++++++++++++++++++++++
 include/linux/scmi_protocol.h       |  64 +++++
 5 files changed, 466 insertions(+), 1 deletion(-)
 create mode 100644 drivers/firmware/arm_scmi/voltage.c

Comments

kernel test robot Oct. 27, 2020, 6:04 a.m. UTC | #1

Hi Cristian,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on soc/for-next]
[also build test WARNING on next-20201026]
[cannot apply to regulator/for-next robh/for-next rockchip/for-next keystone/next arm64/for-next/core linux/master linux-rpi/for-rpi-next at91/at91-next]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Cristian-Marussi/Add-support-for-SCMIv3-0-Voltage-Domain-Protocol-and-SCMI-Regulator/20201027-043404
base:   https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git for-next
config: arm-randconfig-c004-20201026 (attached as .config)
compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[e-mail]>


"coccinelle warnings: (new ones prefixed by >>)"
>> drivers/firmware/arm_scmi/voltage.c:381:11-17: ERROR: application of sizeof to pointer

Please review and possibly fold the followup patch.

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[e-mail]

Cristian Marussi Oct. 27, 2020, 11:07 a.m. UTC | #2

On Tue, Oct 27, 2020 at 02:04:39PM +0800, kernel test robot wrote:
> Hi Cristian,
> 
> Thank you for the patch! Perhaps something to improve:
> 
> [auto build test WARNING on soc/for-next]
> [also build test WARNING on next-20201026]
> [cannot apply to regulator/for-next robh/for-next rockchip/for-next keystone/next arm64/for-next/core linux/master linux-rpi/for-rpi-next at91/at91-next]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch]
> 
> url:    https://github.com/0day-ci/linux/commits/Cristian-Marussi/Add-support-for-SCMIv3-0-Voltage-Domain-Protocol-and-SCMI-Regulator/20201027-043404
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/soc/soc.git for-next
> config: arm-randconfig-c004-20201026 (attached as .config)
> compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <[e-mail]>
> 
> 
> "coccinelle warnings: (new ones prefixed by >>)"
> >> drivers/firmware/arm_scmi/voltage.c:381:11-17: ERROR: application of sizeof to pointer
> 
This is a false positive because the intention here was in fact to
allocate an array of pointers with devm_kcalloc().
Maybe I could explicitly use a sizeof(void *) to avoid fooling
coccicheck ?

Thanks

Cristian

> Please review and possibly fold the followup patch.
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/[e-mail]

Etienne Carriere Oct. 28, 2020, 2:29 p.m. UTC | #3

Hi Cristian,

Some remaining minor comments see below.
FYI I've successfully tested this series (the 4 patches).

Regards,
Etienne

On Mon, 26 Oct 2020 at 21:32, Cristian Marussi <[e-mail]> wrote:
>
> Add SCMI Voltage Domain protocol support.
>
> Signed-off-by: Cristian Marussi <[e-mail]>
> ---
> v2 --> v3
> - restrict segmented voltage domain descriptors to one triplet
> - removed unneeded inline
> - free allocated resources for invalid voltage domain
> - added __must_check to info_get voltage operations
> - added a few comments
> - removed fixed size typing from struct voltage_info
>
> v1 --> v2
> - fix voltage levels query loop to reload full cmd description
>   between iterations as reported by Etienne Carriere
> - ensure rx buffer is properly sized calli scmi_reset_rx_to_maxsz
>   between transfers
> ---
>  drivers/firmware/arm_scmi/Makefile  |   2 +-
>  drivers/firmware/arm_scmi/common.h  |   1 +
>  drivers/firmware/arm_scmi/driver.c  |   2 +
>  drivers/firmware/arm_scmi/voltage.c | 398 ++++++++++++++++++++++++++++
>  include/linux/scmi_protocol.h       |  64 +++++
>  5 files changed, 466 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/firmware/arm_scmi/voltage.c
>
> diff --git a/drivers/firmware/arm_scmi/Makefile b/drivers/firmware/arm_scmi/Makefile
> index bc0d54f8e861..6a2ef63306d6 100644
> --- a/drivers/firmware/arm_scmi/Makefile
> +++ b/drivers/firmware/arm_scmi/Makefile
> @@ -4,7 +4,7 @@ scmi-driver-y = driver.o notify.o
>  scmi-transport-y = shmem.o
>  scmi-transport-$(CONFIG_MAILBOX) += mailbox.o
>  scmi-transport-$(CONFIG_HAVE_ARM_SMCCC_DISCOVERY) += smc.o
> -scmi-protocols-y = base.o clock.o perf.o power.o reset.o sensors.o system.o
> +scmi-protocols-y = base.o clock.o perf.o power.o reset.o sensors.o system.o voltage.o
>  scmi-module-objs := $(scmi-bus-y) $(scmi-driver-y) $(scmi-protocols-y) \
>                     $(scmi-transport-y)
>  obj-$(CONFIG_ARM_SCMI_PROTOCOL) += scmi-module.o
> diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
> index 65063fa948d4..c0fb45e7c3e8 100644
> --- a/drivers/firmware/arm_scmi/common.h
> +++ b/drivers/firmware/arm_scmi/common.h
> @@ -169,6 +169,7 @@ DECLARE_SCMI_REGISTER_UNREGISTER(perf);
>  DECLARE_SCMI_REGISTER_UNREGISTER(power);
>  DECLARE_SCMI_REGISTER_UNREGISTER(reset);
>  DECLARE_SCMI_REGISTER_UNREGISTER(sensors);
> +DECLARE_SCMI_REGISTER_UNREGISTER(voltage);
>  DECLARE_SCMI_REGISTER_UNREGISTER(system);
>
>  #define DEFINE_SCMI_PROTOCOL_REGISTER_UNREGISTER(id, name) \
> diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
> index 3dfd8b6a0ebf..ada35e63feae 100644
> --- a/drivers/firmware/arm_scmi/driver.c
> +++ b/drivers/firmware/arm_scmi/driver.c
> @@ -946,6 +946,7 @@ static int __init scmi_driver_init(void)
>         scmi_power_register();
>         scmi_reset_register();
>         scmi_sensors_register();
> +       scmi_voltage_register();
>         scmi_system_register();
>
>         return platform_driver_register(&scmi_driver);
> @@ -961,6 +962,7 @@ static void __exit scmi_driver_exit(void)
>         scmi_power_unregister();
>         scmi_reset_unregister();
>         scmi_sensors_unregister();
> +       scmi_voltage_unregister();
>         scmi_system_unregister();
>
>         platform_driver_unregister(&scmi_driver);
> diff --git a/drivers/firmware/arm_scmi/voltage.c b/drivers/firmware/arm_scmi/voltage.c
> new file mode 100644
> index 000000000000..2c5a3c8b8649
> --- /dev/null
> +++ b/drivers/firmware/arm_scmi/voltage.c
> @@ -0,0 +1,398 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * System Control and Management Interface (SCMI) Voltage Protocol
> + *
> + * Copyright (C) 2020 ARM Ltd.
> + */
> +
> +#include <linux/scmi_protocol.h>
> +
> +#include "common.h"
> +
> +#define VOLTAGE_DOMS_NUM_MASK          GENMASK(15, 0)
> +#define REMAINING_LEVELS_MASK          GENMASK(31, 16)
> +#define RETURNED_LEVELS_MASK           GENMASK(11, 0)
> +
> +enum scmi_voltage_protocol_cmd {
> +       VOLTAGE_DOMAIN_ATTRIBUTES = 0x3,
> +       VOLTAGE_DESCRIBE_LEVELS = 0x4,
> +       VOLTAGE_CONFIG_SET = 0x5,
> +       VOLTAGE_CONFIG_GET = 0x6,
> +       VOLTAGE_LEVEL_SET = 0x7,
> +       VOLTAGE_LEVEL_GET = 0x8,
> +};
> +
> +struct scmi_msg_resp_protocol_attributes {
> +       __le32 attr;
> +#define NUM_VOLTAGE_DOMAINS(x) (u16)(FIELD_GET(VOLTAGE_DOMS_NUM_MASK, (x)))
> +};
> +
> +struct scmi_msg_resp_domain_attributes {
> +       __le32 attr;
> +       u8 name[SCMI_MAX_STR_SIZE];
> +};
> +
> +struct scmi_msg_cmd_describe_levels {
> +       __le32 domain_id;
> +       __le32 level_index;
> +};
> +
> +struct scmi_msg_resp_describe_levels {
> +       __le32 flags;
> +#define NUM_REMAINING_LEVELS(f)        (u16)(FIELD_GET(REMAINING_LEVELS_MASK, (f)))
> +#define NUM_RETURNED_LEVELS(f) (u16)(FIELD_GET(RETURNED_LEVELS_MASK, (f)))
> +#define SUPPORTS_SEGMENTED_LEVELS(f)   ((f) & BIT(12))
> +       __le32 voltage[];
> +};
> +
> +struct scmi_msg_cmd_config_set {
> +       __le32 domain_id;
> +       __le32 config;
> +};
> +
> +struct scmi_msg_cmd_level_set {
> +       __le32 domain_id;
> +       __le32 flags;
> +       __le32 voltage_level;
> +};
> +
> +struct voltage_info {
> +       u32 version;
> +       u16 num_domains;

Could be an unsigned int.

> +       struct scmi_voltage_info **domains;
> +};
> +
> +static int scmi_protocol_attributes_get(const struct scmi_handle *handle,
> +                                       struct voltage_info *vinfo)
> +{
> +       int ret;
> +       struct scmi_xfer *t;
> +       struct scmi_msg_resp_protocol_attributes *resp;
> +
> +       ret = scmi_xfer_get_init(handle, PROTOCOL_ATTRIBUTES,
> +                                SCMI_PROTOCOL_VOLTAGE, 0, sizeof(*resp), &t);
> +       if (ret)
> +               return ret;
> +
> +       resp = t->rx.buf;
> +       ret = scmi_do_xfer(handle, t);
> +       if (!ret)
> +               vinfo->num_domains =
> +                       NUM_VOLTAGE_DOMAINS(le32_to_cpu(resp->attr));
> +
> +       scmi_xfer_put(handle, t);
> +       return ret;
> +}
> +
> +static inline int scmi_init_voltage_levels(struct device *dev,

Should remove this inline attribute.

> +                                          struct scmi_voltage_info *v,
> +                                          u32 flags, u32 num_returned,
> +                                          u32 num_remaining)
> +{
> +       bool segmented;
> +       u32 num_levels;
> +
> +       segmented = SUPPORTS_SEGMENTED_LEVELS(flags);
> +       num_levels = num_returned + num_remaining;
> +       /*
> +        * segmented levels entries are represented by a single triplet
> +        * returned all in one go.
> +        */
> +       if (!num_levels ||
> +           (segmented && (num_remaining || num_returned != 3))) {
> +               dev_err(dev,
> +                       "Invalid level descriptor(%d/%d/%d) for voltage dom %d\n",
> +                       num_levels, num_returned, num_remaining, v->id);
> +               return -EINVAL;
> +       }
> +
> +       v->levels_uv = devm_kcalloc(dev, num_levels, sizeof(u32), GFP_KERNEL);
> +       if (!v->levels_uv)
> +               return -ENOMEM;
> +
> +       v->num_levels = num_levels;
> +       v->segmented = segmented;
> +
> +       return 0;
> +}
> +
> +static int scmi_voltage_descriptors_get(const struct scmi_handle *handle,
> +                                       struct voltage_info *vinfo)
> +{
> +       int ret, dom;
> +       struct scmi_xfer *td, *tl;
> +       struct device *dev = handle->dev;
> +       struct scmi_msg_resp_domain_attributes *resp_dom;
> +       struct scmi_msg_resp_describe_levels *resp_levels;
> +
> +       ret = scmi_xfer_get_init(handle, VOLTAGE_DOMAIN_ATTRIBUTES,
> +                                SCMI_PROTOCOL_VOLTAGE, sizeof(__le32),
> +                                sizeof(*resp_dom), &td);
> +       if (ret)
> +               return ret;
> +       resp_dom = td->rx.buf;
> +
> +       ret = scmi_xfer_get_init(handle, VOLTAGE_DESCRIBE_LEVELS,
> +                                SCMI_PROTOCOL_VOLTAGE, sizeof(__le64), 0, &tl);
> +       if (ret)
> +               goto outd;
> +       resp_levels = tl->rx.buf;
> +
> +       for (dom = 0; dom < vinfo->num_domains; dom++) {
> +               u32 desc_index = 0;
> +               u16 num_returned = 0, num_remaining = 0;
> +               struct scmi_msg_cmd_describe_levels *cmd;
> +               struct scmi_voltage_info *v;
> +
> +               /* Retrieve domain attributes at first ... */
> +               put_unaligned_le32(dom, td->tx.buf);
> +               ret = scmi_do_xfer(handle, td);
> +               /* Skip domain on comms error */
> +               if (ret)
> +                       continue;
> +
> +               v = devm_kzalloc(dev, sizeof(*v), GFP_KERNEL);
> +               if (!v) {
> +                       ret = -ENOMEM;
> +                       break;
> +               }
> +
> +               v->id = dom;
> +               v->attributes = le32_to_cpu(resp_dom->attr);
> +               strlcpy(v->name, resp_dom->name, SCMI_MAX_STR_SIZE);
> +
> +               cmd = tl->tx.buf;
> +               /* ...then retrieve domain levels descriptions */
> +               do {
> +                       u32 flags;
> +                       int cnt;
> +
> +                       cmd->domain_id = cpu_to_le32(v->id);
> +                       cmd->level_index = desc_index;
> +                       ret = scmi_do_xfer(handle, tl);
> +                       if (ret)
> +                               break;
> +
> +                       flags = le32_to_cpu(resp_levels->flags);
> +                       num_returned = NUM_RETURNED_LEVELS(flags);
> +                       num_remaining = NUM_REMAINING_LEVELS(flags);
> +
> +                       /* Allocate space for num_levels if not already done */
> +                       if (!v->num_levels) {
> +                               ret = scmi_init_voltage_levels(dev, v, flags,
> +                                                              num_returned,
> +                                                              num_remaining);
> +                               if (ret)
> +                                       break;
> +                       }
> +
> +                       if (desc_index + num_returned > v->num_levels) {
> +                               dev_err(handle->dev,
> +                                       "No. of voltage levels can't exceed %d\n",
> +                                       v->num_levels);
> +                               ret = -EINVAL;
> +                               break;
> +                       }
> +
> +                       for (cnt = 0; cnt < num_returned; cnt++) {
> +                               s32 val;
> +
> +                               val =
> +                                   (s32)le32_to_cpu(resp_levels->voltage[cnt]);
> +                               v->levels_uv[desc_index + cnt] = val;
> +                               if (val < 0)
> +                                       v->negative_volts_allowed = true;
> +                       }
> +
> +                       desc_index += num_returned;
> +
> +                       scmi_reset_rx_to_maxsz(handle, tl);
> +                       /* check both to avoid infinite loop due to buggy fw */
> +               } while (num_returned && num_remaining);
> +
> +               /*
> +                * Bail out only on memory errors, just skip domain and free
> +                * on any other error.
> +                */
> +               if (!ret) {
> +                       vinfo->domains[dom] = v;
> +               } else if (ret != -ENOMEM) {
> +                       devm_kfree(dev, v->levels_uv);
> +                       devm_kfree(dev, v);
> +               } else {
> +                       break;
> +               }
> +
> +               scmi_reset_rx_to_maxsz(handle, td);
> +       }
> +
> +       scmi_xfer_put(handle, tl);
> +outd:
> +       scmi_xfer_put(handle, td);
> +
> +       return ret;
> +}
> +
> +static int __scmi_voltage_get_u32(const struct scmi_handle *handle,
> +                                 u8 cmd_id, u32 domain_id, u32 *value)
> +{
> +       int ret;
> +       struct scmi_xfer *t;
> +       struct voltage_info *vinfo = handle->voltage_priv;
> +
> +       if (domain_id >= vinfo->num_domains)
> +               return -EINVAL;
> +
> +       ret = scmi_xfer_get_init(handle, cmd_id,
> +                                SCMI_PROTOCOL_VOLTAGE,
> +                                sizeof(__le32), 0, &t);
> +       if (ret)
> +               return ret;
> +
> +       put_unaligned_le32(domain_id, t->tx.buf);
> +       ret = scmi_do_xfer(handle, t);
> +       if (!ret)
> +               *value = get_unaligned_le32(t->rx.buf);
> +
> +       scmi_xfer_put(handle, t);
> +       return ret;
> +}
> +
> +static int scmi_voltage_config_set(const struct scmi_handle *handle,
> +                                  u32 domain_id, u32 config)
> +{
> +       int ret;
> +       struct scmi_xfer *t;
> +       struct voltage_info *vinfo = handle->voltage_priv;
> +       struct scmi_msg_cmd_config_set *cmd;
> +
> +       if (domain_id >= vinfo->num_domains)
> +               return -EINVAL;
> +
> +       ret = scmi_xfer_get_init(handle, VOLTAGE_CONFIG_SET,
> +                                SCMI_PROTOCOL_VOLTAGE,
> +                                sizeof(*cmd), 0, &t);
> +       if (ret)
> +               return ret;
> +
> +       cmd = t->tx.buf;
> +       cmd->domain_id = cpu_to_le32(domain_id);
> +       cmd->config = cpu_to_le32(config & GENMASK(3, 0));
> +
> +       ret = scmi_do_xfer(handle, t);
> +
> +       scmi_xfer_put(handle, t);
> +       return ret;
> +}
> +
> +static int scmi_voltage_config_get(const struct scmi_handle *handle,
> +                                  u32 domain_id, u32 *config)
> +{
> +       return __scmi_voltage_get_u32(handle, VOLTAGE_CONFIG_GET,
> +                                     domain_id, config);
> +}
> +
> +static int scmi_voltage_level_set(const struct scmi_handle *handle,
> +                                 u32 domain_id, u32 flags, s32 volt_uV)
> +{
> +       int ret;
> +       struct scmi_xfer *t;
> +       struct voltage_info *vinfo = handle->voltage_priv;
> +       struct scmi_msg_cmd_level_set *cmd;
> +
> +       if (domain_id >= vinfo->num_domains)
> +               return -EINVAL;
> +
> +       ret = scmi_xfer_get_init(handle, VOLTAGE_LEVEL_SET,
> +                                SCMI_PROTOCOL_VOLTAGE,
> +                                sizeof(*cmd), 0, &t);
> +       if (ret)
> +               return ret;
> +
> +       cmd = t->tx.buf;
> +       cmd->domain_id = cpu_to_le32(domain_id);
> +       cmd->flags = cpu_to_le32(flags);
> +       cmd->voltage_level = cpu_to_le32(volt_uV);
> +
> +       ret = scmi_do_xfer(handle, t);
> +
> +       scmi_xfer_put(handle, t);
> +       return ret;
> +}
> +
> +static int scmi_voltage_level_get(const struct scmi_handle *handle,
> +                                 u32 domain_id, s32 *volt_uV)
> +{
> +       return __scmi_voltage_get_u32(handle, VOLTAGE_LEVEL_GET,
> +                                     domain_id, (u32 *)volt_uV);
> +}
> +
> +static const struct scmi_voltage_info * __must_check
> +scmi_voltage_info_get(const struct scmi_handle *handle, u32 domain_id)
> +{
> +       struct voltage_info *vinfo = handle->voltage_priv;
> +
> +       if (domain_id >= vinfo->num_domains)
> +               return NULL;
> +
> +       return vinfo->domains[domain_id];
> +}
> +
> +static int scmi_voltage_domains_num_get(const struct scmi_handle *handle)
> +{
> +       struct voltage_info *vinfo = handle->voltage_priv;
> +
> +       return vinfo->num_domains;
> +}
> +
> +static struct scmi_voltage_ops voltage_ops = {
> +       .num_domains_get = scmi_voltage_domains_num_get,
> +       .info_get = scmi_voltage_info_get,
> +       .config_set = scmi_voltage_config_set,
> +       .config_get = scmi_voltage_config_get,
> +       .level_set = scmi_voltage_level_set,
> +       .level_get = scmi_voltage_level_get,
> +};
> +
> +static int scmi_voltage_protocol_init(struct scmi_handle *handle)
> +{
> +       int ret;
> +       u32 version;
> +       struct voltage_info *vinfo;
> +
> +       ret = scmi_version_get(handle, SCMI_PROTOCOL_VOLTAGE, &version);
> +       if (ret)
> +               return ret;
> +
> +       dev_dbg(handle->dev, "Voltage Version %d.%d\n",
> +               PROTOCOL_REV_MAJOR(version), PROTOCOL_REV_MINOR(version));
> +
> +       vinfo = devm_kzalloc(handle->dev, sizeof(*vinfo), GFP_KERNEL);
> +       if (!vinfo)
> +               return -ENOMEM;
> +       vinfo->version = version;
> +
> +       ret = scmi_protocol_attributes_get(handle, vinfo);
> +       if (ret)
> +               return ret;
> +
> +       if (vinfo->num_domains) {
> +               vinfo->domains = devm_kcalloc(handle->dev, vinfo->num_domains,
> +                                             sizeof(vinfo->domains),
> +                                             GFP_KERNEL);
> +               if (!vinfo->domains)
> +                       return -ENOMEM;
> +               ret = scmi_voltage_descriptors_get(handle, vinfo);
> +               if (ret)
> +                       return ret;
> +       } else {
> +               dev_warn(handle->dev, "No Voltage domains found.\n");
> +       }
> +
> +       handle->voltage_ops = &voltage_ops;
> +       handle->voltage_priv = vinfo;
> +
> +       return 0;
> +}
> +
> +DEFINE_SCMI_PROTOCOL_REGISTER_UNREGISTER(SCMI_PROTOCOL_VOLTAGE, voltage)
> diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
> index 9cd312a1ff92..181fdebc2793 100644
> --- a/include/linux/scmi_protocol.h
> +++ b/include/linux/scmi_protocol.h
> @@ -209,6 +209,64 @@ struct scmi_reset_ops {
>         int (*deassert)(const struct scmi_handle *handle, u32 domain);
>  };
>
> +/**
> + * struct scmi_voltage_info - describe one available SCMI Voltage Domain
> + *
> + * @id: the domain ID as advertised by the platform
> + * @segmented: defines the layout of the entries of array @levels_uv.
> + *            - when True the entries are to be interpreted as triplets,
> + *              each defining a segment representing a range of equally
> + *              space voltages: <lowest_volts>, <highest_volt>, <step_uV>
> + *            - when False the entries simply represent a single discrete
> + *              supported voltage level
> + * @negative_volts_allowed: True if any of the entries of @levels_uv represent
> + *                         a negative voltage.
> + * @attributes: represents Voltage Domain advertised attributes
> + * @name: name assigned to the Voltage Domain by platform
> + * @num_levels: number of total entries in @levels_uv.
> + * @levels_uv: array of entries describing the available voltage levels for
> + *            this domain.
> + */
> +struct scmi_voltage_info {
> +       unsigned int id;
> +       bool segmented;
> +#define SCMI_VOLTAGE_SEGMENT_LOW       0
> +#define SCMI_VOLTAGE_SEGMENT_HIGH      1
> +#define SCMI_VOLTAGE_SEGMENT_STEP      2

Maybe move these macros before 'int *level_us;' as these are indices
in that array.

> +       bool negative_volts_allowed;
> +       unsigned int attributes;
> +       char name[SCMI_MAX_STR_SIZE];
> +       unsigned int num_levels;
> +       int *levels_uv;
> +};
> +
> +/**
> + * struct scmi_voltage_ops - represents the various operations provided
> + * by SCMI Voltage Protocol
> + *
> + * @num_domains_get: get the count of voltage domains provided by SCMI
> + * @info_get: get the information of the specified domain
> + * @config_set: set the config for the specified domain
> + * @config_get: get the config of the specified domain
> + * @level_set: set the voltage level for the specified domain
> + * @level_get: get the voltage level of the specified domain
> + */
> +struct scmi_voltage_ops {
> +       int (*num_domains_get)(const struct scmi_handle *handle);
> +       const struct scmi_voltage_info __must_check *(*info_get)
> +               (const struct scmi_handle *handle, u32 domain_id);
> +       int (*config_set)(const struct scmi_handle *handle, u32 domain_id,
> +                         u32 config);
> +#define        SCMI_VOLTAGE_ARCH_STATE_OFF             0x0
> +#define        SCMI_VOLTAGE_ARCH_STATE_ON              0x7
> +       int (*config_get)(const struct scmi_handle *handle, u32 domain_id,
> +                         u32 *config);
> +       int (*level_set)(const struct scmi_handle *handle, u32 domain_id,
> +                        u32 flags, s32 volt_uV);
> +       int (*level_get)(const struct scmi_handle *handle, u32 domain_id,
> +                        s32 *volt_uV);
> +};
> +
>  /**
>   * struct scmi_notify_ops  - represents notifications' operations provided by
>   * SCMI core
> @@ -262,6 +320,7 @@ struct scmi_notify_ops {
>   * @clk_ops: pointer to set of clock protocol operations
>   * @sensor_ops: pointer to set of sensor protocol operations
>   * @reset_ops: pointer to set of reset protocol operations
> + * @voltage_ops: pointer to set of voltage protocol operations
>   * @notify_ops: pointer to set of notifications related operations
>   * @perf_priv: pointer to private data structure specific to performance
>   *     protocol(for internal use only)
> @@ -273,6 +332,8 @@ struct scmi_notify_ops {
>   *     protocol(for internal use only)
>   * @reset_priv: pointer to private data structure specific to reset
>   *     protocol(for internal use only)
> + * @voltage_priv: pointer to private data structure specific to voltage
> + *     protocol(for internal use only)
>   * @notify_priv: pointer to private data structure specific to notifications
>   *     (for internal use only)
>   */
> @@ -284,6 +345,7 @@ struct scmi_handle {
>         const struct scmi_power_ops *power_ops;
>         const struct scmi_sensor_ops *sensor_ops;
>         const struct scmi_reset_ops *reset_ops;
> +       const struct scmi_voltage_ops *voltage_ops;
>         const struct scmi_notify_ops *notify_ops;
>         /* for protocol internal use */
>         void *perf_priv;
> @@ -291,6 +353,7 @@ struct scmi_handle {
>         void *power_priv;
>         void *sensor_priv;
>         void *reset_priv;
> +       void *voltage_priv;
>         void *notify_priv;
>         void *system_priv;
>  };
> @@ -303,6 +366,7 @@ enum scmi_std_protocol {
>         SCMI_PROTOCOL_CLOCK = 0x14,
>         SCMI_PROTOCOL_SENSOR = 0x15,
>         SCMI_PROTOCOL_RESET = 0x16,
> +       SCMI_PROTOCOL_VOLTAGE = 0x17,
>  };
>
>  enum scmi_system_events {
> --
> 2.17.1
>

Cristian Marussi Oct. 28, 2020, 8:44 p.m. UTC | #4

On Wed, Oct 28, 2020 at 03:29:57PM +0100, Etienne Carriere wrote:
> Hi Cristian,
> 
> Some remaining minor comments see below.
> FYI I've successfully tested this series (the 4 patches).
> 

Hi

Thanks a lot !

Replies inline down below.

[snip]
> > +struct scmi_msg_cmd_config_set {
> > +       __le32 domain_id;
> > +       __le32 config;
> > +};
> > +
> > +struct scmi_msg_cmd_level_set {
> > +       __le32 domain_id;
> > +       __le32 flags;
> > +       __le32 voltage_level;
> > +};
> > +
> > +struct voltage_info {
> > +       u32 version;
> > +       u16 num_domains;
> 
> Could be an unsigned int.
> 

I tend to use fixed size types matching the protocols messages sizing on
the internal while exposing non-fixed size types in scmi_protocol.h like
in scmi_voltage_info, but these indeed are values exposed directly to
the user afterwards. Any other reason to prefer non-fixed size here ?

> > +       struct scmi_voltage_info **domains;
> > +};
> > +
> > +static int scmi_protocol_attributes_get(const struct scmi_handle *handle,
> > +                                       struct voltage_info *vinfo)
> > +{
> > +       int ret;
> > +       struct scmi_xfer *t;
> > +       struct scmi_msg_resp_protocol_attributes *resp;
> > +
> > +       ret = scmi_xfer_get_init(handle, PROTOCOL_ATTRIBUTES,
> > +                                SCMI_PROTOCOL_VOLTAGE, 0, sizeof(*resp), &t);
> > +       if (ret)
> > +               return ret;
> > +
> > +       resp = t->rx.buf;
> > +       ret = scmi_do_xfer(handle, t);
> > +       if (!ret)
> > +               vinfo->num_domains =
> > +                       NUM_VOLTAGE_DOMAINS(le32_to_cpu(resp->attr));
> > +
> > +       scmi_xfer_put(handle, t);
> > +       return ret;
> > +}
> > +
> > +static inline int scmi_init_voltage_levels(struct device *dev,
> 
> Should remove this inline attribute.
> 

Ah right, I removed one and left this. I'll do.

> > +                                          struct scmi_voltage_info *v,
> > +                                          u32 flags, u32 num_returned,
> > +                                          u32 num_remaining)

[snip]

> > +DEFINE_SCMI_PROTOCOL_REGISTER_UNREGISTER(SCMI_PROTOCOL_VOLTAGE, voltage)
> > diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
> > index 9cd312a1ff92..181fdebc2793 100644
> > --- a/include/linux/scmi_protocol.h
> > +++ b/include/linux/scmi_protocol.h
> > @@ -209,6 +209,64 @@ struct scmi_reset_ops {
> >         int (*deassert)(const struct scmi_handle *handle, u32 domain);
> >  };
> >
> > +/**
> > + * struct scmi_voltage_info - describe one available SCMI Voltage Domain
> > + *
> > + * @id: the domain ID as advertised by the platform
> > + * @segmented: defines the layout of the entries of array @levels_uv.
> > + *            - when True the entries are to be interpreted as triplets,
> > + *              each defining a segment representing a range of equally
> > + *              space voltages: <lowest_volts>, <highest_volt>, <step_uV>
> > + *            - when False the entries simply represent a single discrete
> > + *              supported voltage level
> > + * @negative_volts_allowed: True if any of the entries of @levels_uv represent
> > + *                         a negative voltage.
> > + * @attributes: represents Voltage Domain advertised attributes
> > + * @name: name assigned to the Voltage Domain by platform
> > + * @num_levels: number of total entries in @levels_uv.
> > + * @levels_uv: array of entries describing the available voltage levels for
> > + *            this domain.
> > + */
> > +struct scmi_voltage_info {
> > +       unsigned int id;
> > +       bool segmented;
> > +#define SCMI_VOLTAGE_SEGMENT_LOW       0
> > +#define SCMI_VOLTAGE_SEGMENT_HIGH      1
> > +#define SCMI_VOLTAGE_SEGMENT_STEP      2
> 
> Maybe move these macros before 'int *level_us;' as these are indices
> in that array.
> 

Right, I'll do.

Thanks

Cristian

> > +       bool negative_volts_allowed;
> > +       unsigned int attributes;
> > +       char name[SCMI_MAX_STR_SIZE];
> > +       unsigned int num_levels;
> > +       int *levels_uv;
> > +};
> > +
> > +/**
> > + * struct scmi_voltage_ops - represents the various operations provided
> > + * by SCMI Voltage Protocol
> > + *
> > + * @num_domains_get: get the count of voltage domains provided by SCMI
> > + * @info_get: get the information of the specified domain
> > + * @config_set: set the config for the specified domain
> > + * @config_get: get the config of the specified domain
> > + * @level_set: set the voltage level for the specified domain
> > + * @level_get: get the voltage level of the specified domain
> > + */
> > +struct scmi_voltage_ops {
> > +       int (*num_domains_get)(const struct scmi_handle *handle);
> > +       const struct scmi_voltage_info __must_check *(*info_get)
> > +               (const struct scmi_handle *handle, u32 domain_id);
> > +       int (*config_set)(const struct scmi_handle *handle, u32 domain_id,
> > +                         u32 config);
> > +#define        SCMI_VOLTAGE_ARCH_STATE_OFF             0x0
> > +#define        SCMI_VOLTAGE_ARCH_STATE_ON              0x7
> > +       int (*config_get)(const struct scmi_handle *handle, u32 domain_id,
> > +                         u32 *config);
> > +       int (*level_set)(const struct scmi_handle *handle, u32 domain_id,
> > +                        u32 flags, s32 volt_uV);
> > +       int (*level_get)(const struct scmi_handle *handle, u32 domain_id,
> > +                        s32 *volt_uV);
> > +};
> > +
> >  /**
> >   * struct scmi_notify_ops  - represents notifications' operations provided by
> >   * SCMI core
> > @@ -262,6 +320,7 @@ struct scmi_notify_ops {
> >   * @clk_ops: pointer to set of clock protocol operations
> >   * @sensor_ops: pointer to set of sensor protocol operations
> >   * @reset_ops: pointer to set of reset protocol operations
> > + * @voltage_ops: pointer to set of voltage protocol operations
> >   * @notify_ops: pointer to set of notifications related operations
> >   * @perf_priv: pointer to private data structure specific to performance
> >   *     protocol(for internal use only)
> > @@ -273,6 +332,8 @@ struct scmi_notify_ops {
> >   *     protocol(for internal use only)
> >   * @reset_priv: pointer to private data structure specific to reset
> >   *     protocol(for internal use only)
> > + * @voltage_priv: pointer to private data structure specific to voltage
> > + *     protocol(for internal use only)
> >   * @notify_priv: pointer to private data structure specific to notifications
> >   *     (for internal use only)
> >   */
> > @@ -284,6 +345,7 @@ struct scmi_handle {
> >         const struct scmi_power_ops *power_ops;
> >         const struct scmi_sensor_ops *sensor_ops;
> >         const struct scmi_reset_ops *reset_ops;
> > +       const struct scmi_voltage_ops *voltage_ops;
> >         const struct scmi_notify_ops *notify_ops;
> >         /* for protocol internal use */
> >         void *perf_priv;
> > @@ -291,6 +353,7 @@ struct scmi_handle {
> >         void *power_priv;
> >         void *sensor_priv;
> >         void *reset_priv;
> > +       void *voltage_priv;
> >         void *notify_priv;
> >         void *system_priv;
> >  };
> > @@ -303,6 +366,7 @@ enum scmi_std_protocol {
> >         SCMI_PROTOCOL_CLOCK = 0x14,
> >         SCMI_PROTOCOL_SENSOR = 0x15,
> >         SCMI_PROTOCOL_RESET = 0x16,
> > +       SCMI_PROTOCOL_VOLTAGE = 0x17,
> >  };
> >
> >  enum scmi_system_events {
> > --
> > 2.17.1
> >

Etienne Carriere Oct. 29, 2020, 11:21 a.m. UTC | #5

On Wed, 28 Oct 2020 at 21:44, Cristian Marussi <[e-mail]> wrote:
>
> On Wed, Oct 28, 2020 at 03:29:57PM +0100, Etienne Carriere wrote:
> > Hi Cristian,
> >
> > Some remaining minor comments see below.
> > FYI I've successfully tested this series (the 4 patches).
> >
>
> Hi
>
> Thanks a lot !
>
> Replies inline down below.
>
> [snip]
> > > +struct scmi_msg_cmd_config_set {
> > > +       __le32 domain_id;
> > > +       __le32 config;
> > > +};
> > > +
> > > +struct scmi_msg_cmd_level_set {
> > > +       __le32 domain_id;
> > > +       __le32 flags;
> > > +       __le32 voltage_level;
> > > +};
> > > +
> > > +struct voltage_info {
> > > +       u32 version;
> > > +       u16 num_domains;
> >
> > Could be an unsigned int.
> >
>
> I tend to use fixed size types matching the protocols messages sizing on
> the internal while exposing non-fixed size types in scmi_protocol.h like
> in scmi_voltage_info, but these indeed are values exposed directly to
> the user afterwards. Any other reason to prefer non-fixed size here ?

I think fixed size should be used where really needed.
Since in this structure you're quite abstracted from the protocol, a generic
type is preferred I think.

Regards,
Etienne

>
> > > +       struct scmi_voltage_info **domains;
> > > +};
> > > +
> > > +static int scmi_protocol_attributes_get(const struct scmi_handle *handle,
> > > +                                       struct voltage_info *vinfo)
> > > +{
> > > +       int ret;
> > > +       struct scmi_xfer *t;
> > > +       struct scmi_msg_resp_protocol_attributes *resp;
> > > +
> > > +       ret = scmi_xfer_get_init(handle, PROTOCOL_ATTRIBUTES,
> > > +                                SCMI_PROTOCOL_VOLTAGE, 0, sizeof(*resp), &t);
> > > +       if (ret)
> > > +               return ret;
> > > +
> > > +       resp = t->rx.buf;
> > > +       ret = scmi_do_xfer(handle, t);
> > > +       if (!ret)
> > > +               vinfo->num_domains =
> > > +                       NUM_VOLTAGE_DOMAINS(le32_to_cpu(resp->attr));
> > > +
> > > +       scmi_xfer_put(handle, t);
> > > +       return ret;
> > > +}
> > > +
> > > +static inline int scmi_init_voltage_levels(struct device *dev,
> >
> > Should remove this inline attribute.
> >
>
> Ah right, I removed one and left this. I'll do.
>
> > > +                                          struct scmi_voltage_info *v,
> > > +                                          u32 flags, u32 num_returned,
> > > +                                          u32 num_remaining)
>
> [snip]
>
> > > +DEFINE_SCMI_PROTOCOL_REGISTER_UNREGISTER(SCMI_PROTOCOL_VOLTAGE, voltage)
> > > diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
> > > index 9cd312a1ff92..181fdebc2793 100644
> > > --- a/include/linux/scmi_protocol.h
> > > +++ b/include/linux/scmi_protocol.h
> > > @@ -209,6 +209,64 @@ struct scmi_reset_ops {
> > >         int (*deassert)(const struct scmi_handle *handle, u32 domain);
> > >  };
> > >
> > > +/**
> > > + * struct scmi_voltage_info - describe one available SCMI Voltage Domain
> > > + *
> > > + * @id: the domain ID as advertised by the platform
> > > + * @segmented: defines the layout of the entries of array @levels_uv.
> > > + *            - when True the entries are to be interpreted as triplets,
> > > + *              each defining a segment representing a range of equally
> > > + *              space voltages: <lowest_volts>, <highest_volt>, <step_uV>
> > > + *            - when False the entries simply represent a single discrete
> > > + *              supported voltage level
> > > + * @negative_volts_allowed: True if any of the entries of @levels_uv represent
> > > + *                         a negative voltage.
> > > + * @attributes: represents Voltage Domain advertised attributes
> > > + * @name: name assigned to the Voltage Domain by platform
> > > + * @num_levels: number of total entries in @levels_uv.
> > > + * @levels_uv: array of entries describing the available voltage levels for
> > > + *            this domain.
> > > + */
> > > +struct scmi_voltage_info {
> > > +       unsigned int id;
> > > +       bool segmented;
> > > +#define SCMI_VOLTAGE_SEGMENT_LOW       0
> > > +#define SCMI_VOLTAGE_SEGMENT_HIGH      1
> > > +#define SCMI_VOLTAGE_SEGMENT_STEP      2
> >
> > Maybe move these macros before 'int *level_us;' as these are indices
> > in that array.
> >
>
> Right, I'll do.
>
> Thanks
>
> Cristian
>
> > > +       bool negative_volts_allowed;
> > > +       unsigned int attributes;
> > > +       char name[SCMI_MAX_STR_SIZE];
> > > +       unsigned int num_levels;
> > > +       int *levels_uv;
> > > +};
> > > +
> > > +/**
> > > + * struct scmi_voltage_ops - represents the various operations provided
> > > + * by SCMI Voltage Protocol
> > > + *
> > > + * @num_domains_get: get the count of voltage domains provided by SCMI
> > > + * @info_get: get the information of the specified domain
> > > + * @config_set: set the config for the specified domain
> > > + * @config_get: get the config of the specified domain
> > > + * @level_set: set the voltage level for the specified domain
> > > + * @level_get: get the voltage level of the specified domain
> > > + */
> > > +struct scmi_voltage_ops {
> > > +       int (*num_domains_get)(const struct scmi_handle *handle);
> > > +       const struct scmi_voltage_info __must_check *(*info_get)
> > > +               (const struct scmi_handle *handle, u32 domain_id);
> > > +       int (*config_set)(const struct scmi_handle *handle, u32 domain_id,
> > > +                         u32 config);
> > > +#define        SCMI_VOLTAGE_ARCH_STATE_OFF             0x0
> > > +#define        SCMI_VOLTAGE_ARCH_STATE_ON              0x7
> > > +       int (*config_get)(const struct scmi_handle *handle, u32 domain_id,
> > > +                         u32 *config);
> > > +       int (*level_set)(const struct scmi_handle *handle, u32 domain_id,
> > > +                        u32 flags, s32 volt_uV);
> > > +       int (*level_get)(const struct scmi_handle *handle, u32 domain_id,
> > > +                        s32 *volt_uV);
> > > +};
> > > +
> > >  /**
> > >   * struct scmi_notify_ops  - represents notifications' operations provided by
> > >   * SCMI core
> > > @@ -262,6 +320,7 @@ struct scmi_notify_ops {
> > >   * @clk_ops: pointer to set of clock protocol operations
> > >   * @sensor_ops: pointer to set of sensor protocol operations
> > >   * @reset_ops: pointer to set of reset protocol operations
> > > + * @voltage_ops: pointer to set of voltage protocol operations
> > >   * @notify_ops: pointer to set of notifications related operations
> > >   * @perf_priv: pointer to private data structure specific to performance
> > >   *     protocol(for internal use only)
> > > @@ -273,6 +332,8 @@ struct scmi_notify_ops {
> > >   *     protocol(for internal use only)
> > >   * @reset_priv: pointer to private data structure specific to reset
> > >   *     protocol(for internal use only)
> > > + * @voltage_priv: pointer to private data structure specific to voltage
> > > + *     protocol(for internal use only)
> > >   * @notify_priv: pointer to private data structure specific to notifications
> > >   *     (for internal use only)
> > >   */
> > > @@ -284,6 +345,7 @@ struct scmi_handle {
> > >         const struct scmi_power_ops *power_ops;
> > >         const struct scmi_sensor_ops *sensor_ops;
> > >         const struct scmi_reset_ops *reset_ops;
> > > +       const struct scmi_voltage_ops *voltage_ops;
> > >         const struct scmi_notify_ops *notify_ops;
> > >         /* for protocol internal use */
> > >         void *perf_priv;
> > > @@ -291,6 +353,7 @@ struct scmi_handle {
> > >         void *power_priv;
> > >         void *sensor_priv;
> > >         void *reset_priv;
> > > +       void *voltage_priv;
> > >         void *notify_priv;
> > >         void *system_priv;
> > >  };
> > > @@ -303,6 +366,7 @@ enum scmi_std_protocol {
> > >         SCMI_PROTOCOL_CLOCK = 0x14,
> > >         SCMI_PROTOCOL_SENSOR = 0x15,
> > >         SCMI_PROTOCOL_RESET = 0x16,
> > > +       SCMI_PROTOCOL_VOLTAGE = 0x17,
> > >  };
> > >
> > >  enum scmi_system_events {
> > > --
> > > 2.17.1
> > >

Cristian Marussi Oct. 29, 2020, 11:44 a.m. UTC | #6

On Thu, Oct 29, 2020 at 12:21:56PM +0100, Etienne Carriere wrote:
> On Wed, 28 Oct 2020 at 21:44, Cristian Marussi <[e-mail]> wrote:
> >
> > On Wed, Oct 28, 2020 at 03:29:57PM +0100, Etienne Carriere wrote:
> > > Hi Cristian,
> > >
> > > Some remaining minor comments see below.
> > > FYI I've successfully tested this series (the 4 patches).
> > >
> >
> > Hi
> >
> > Thanks a lot !
> >
> > Replies inline down below.
> >
> > [snip]
> > > > +struct scmi_msg_cmd_config_set {
> > > > +       __le32 domain_id;
> > > > +       __le32 config;
> > > > +};
> > > > +
> > > > +struct scmi_msg_cmd_level_set {
> > > > +       __le32 domain_id;
> > > > +       __le32 flags;
> > > > +       __le32 voltage_level;
> > > > +};
> > > > +
> > > > +struct voltage_info {
> > > > +       u32 version;
> > > > +       u16 num_domains;
> > >
> > > Could be an unsigned int.
> > >
> >
> > I tend to use fixed size types matching the protocols messages sizing on
> > the internal while exposing non-fixed size types in scmi_protocol.h like
> > in scmi_voltage_info, but these indeed are values exposed directly to
> > the user afterwards. Any other reason to prefer non-fixed size here ?
> 
> I think fixed size should be used where really needed.
> Since in this structure you're quite abstracted from the protocol, a generic
> type is preferred I think.
> 

Ok, I'll fix in V4.

Thanks

Cristian

> Regards,
> Etienne
> 
> >
> > > > +       struct scmi_voltage_info **domains;
> > > > +};
> > > > +
> > > > +static int scmi_protocol_attributes_get(const struct scmi_handle *handle,
> > > > +                                       struct voltage_info *vinfo)
> > > > +{
> > > > +       int ret;
> > > > +       struct scmi_xfer *t;
> > > > +       struct scmi_msg_resp_protocol_attributes *resp;
> > > > +
> > > > +       ret = scmi_xfer_get_init(handle, PROTOCOL_ATTRIBUTES,
> > > > +                                SCMI_PROTOCOL_VOLTAGE, 0, sizeof(*resp), &t);
> > > > +       if (ret)
> > > > +               return ret;
> > > > +
> > > > +       resp = t->rx.buf;
> > > > +       ret = scmi_do_xfer(handle, t);
> > > > +       if (!ret)
> > > > +               vinfo->num_domains =
> > > > +                       NUM_VOLTAGE_DOMAINS(le32_to_cpu(resp->attr));
> > > > +
> > > > +       scmi_xfer_put(handle, t);
> > > > +       return ret;
> > > > +}
> > > > +
> > > > +static inline int scmi_init_voltage_levels(struct device *dev,
> > >
> > > Should remove this inline attribute.
> > >
> >
> > Ah right, I removed one and left this. I'll do.
> >
> > > > +                                          struct scmi_voltage_info *v,
> > > > +                                          u32 flags, u32 num_returned,
> > > > +                                          u32 num_remaining)
> >
> > [snip]
> >
> > > > +DEFINE_SCMI_PROTOCOL_REGISTER_UNREGISTER(SCMI_PROTOCOL_VOLTAGE, voltage)
> > > > diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
> > > > index 9cd312a1ff92..181fdebc2793 100644
> > > > --- a/include/linux/scmi_protocol.h
> > > > +++ b/include/linux/scmi_protocol.h
> > > > @@ -209,6 +209,64 @@ struct scmi_reset_ops {
> > > >         int (*deassert)(const struct scmi_handle *handle, u32 domain);
> > > >  };
> > > >
> > > > +/**
> > > > + * struct scmi_voltage_info - describe one available SCMI Voltage Domain
> > > > + *
> > > > + * @id: the domain ID as advertised by the platform
> > > > + * @segmented: defines the layout of the entries of array @levels_uv.
> > > > + *            - when True the entries are to be interpreted as triplets,
> > > > + *              each defining a segment representing a range of equally
> > > > + *              space voltages: <lowest_volts>, <highest_volt>, <step_uV>
> > > > + *            - when False the entries simply represent a single discrete
> > > > + *              supported voltage level
> > > > + * @negative_volts_allowed: True if any of the entries of @levels_uv represent
> > > > + *                         a negative voltage.
> > > > + * @attributes: represents Voltage Domain advertised attributes
> > > > + * @name: name assigned to the Voltage Domain by platform
> > > > + * @num_levels: number of total entries in @levels_uv.
> > > > + * @levels_uv: array of entries describing the available voltage levels for
> > > > + *            this domain.
> > > > + */
> > > > +struct scmi_voltage_info {
> > > > +       unsigned int id;
> > > > +       bool segmented;
> > > > +#define SCMI_VOLTAGE_SEGMENT_LOW       0
> > > > +#define SCMI_VOLTAGE_SEGMENT_HIGH      1
> > > > +#define SCMI_VOLTAGE_SEGMENT_STEP      2
> > >
> > > Maybe move these macros before 'int *level_us;' as these are indices
> > > in that array.
> > >
> >
> > Right, I'll do.
> >
> > Thanks
> >
> > Cristian
> >
> > > > +       bool negative_volts_allowed;
> > > > +       unsigned int attributes;
> > > > +       char name[SCMI_MAX_STR_SIZE];
> > > > +       unsigned int num_levels;
> > > > +       int *levels_uv;
> > > > +};
> > > > +
> > > > +/**
> > > > + * struct scmi_voltage_ops - represents the various operations provided
> > > > + * by SCMI Voltage Protocol
> > > > + *
> > > > + * @num_domains_get: get the count of voltage domains provided by SCMI
> > > > + * @info_get: get the information of the specified domain
> > > > + * @config_set: set the config for the specified domain
> > > > + * @config_get: get the config of the specified domain
> > > > + * @level_set: set the voltage level for the specified domain
> > > > + * @level_get: get the voltage level of the specified domain
> > > > + */
> > > > +struct scmi_voltage_ops {
> > > > +       int (*num_domains_get)(const struct scmi_handle *handle);
> > > > +       const struct scmi_voltage_info __must_check *(*info_get)
> > > > +               (const struct scmi_handle *handle, u32 domain_id);
> > > > +       int (*config_set)(const struct scmi_handle *handle, u32 domain_id,
> > > > +                         u32 config);
> > > > +#define        SCMI_VOLTAGE_ARCH_STATE_OFF             0x0
> > > > +#define        SCMI_VOLTAGE_ARCH_STATE_ON              0x7
> > > > +       int (*config_get)(const struct scmi_handle *handle, u32 domain_id,
> > > > +                         u32 *config);
> > > > +       int (*level_set)(const struct scmi_handle *handle, u32 domain_id,
> > > > +                        u32 flags, s32 volt_uV);
> > > > +       int (*level_get)(const struct scmi_handle *handle, u32 domain_id,
> > > > +                        s32 *volt_uV);
> > > > +};
> > > > +
> > > >  /**
> > > >   * struct scmi_notify_ops  - represents notifications' operations provided by
> > > >   * SCMI core
> > > > @@ -262,6 +320,7 @@ struct scmi_notify_ops {
> > > >   * @clk_ops: pointer to set of clock protocol operations
> > > >   * @sensor_ops: pointer to set of sensor protocol operations
> > > >   * @reset_ops: pointer to set of reset protocol operations
> > > > + * @voltage_ops: pointer to set of voltage protocol operations
> > > >   * @notify_ops: pointer to set of notifications related operations
> > > >   * @perf_priv: pointer to private data structure specific to performance
> > > >   *     protocol(for internal use only)
> > > > @@ -273,6 +332,8 @@ struct scmi_notify_ops {
> > > >   *     protocol(for internal use only)
> > > >   * @reset_priv: pointer to private data structure specific to reset
> > > >   *     protocol(for internal use only)
> > > > + * @voltage_priv: pointer to private data structure specific to voltage
> > > > + *     protocol(for internal use only)
> > > >   * @notify_priv: pointer to private data structure specific to notifications
> > > >   *     (for internal use only)
> > > >   */
> > > > @@ -284,6 +345,7 @@ struct scmi_handle {
> > > >         const struct scmi_power_ops *power_ops;
> > > >         const struct scmi_sensor_ops *sensor_ops;
> > > >         const struct scmi_reset_ops *reset_ops;
> > > > +       const struct scmi_voltage_ops *voltage_ops;
> > > >         const struct scmi_notify_ops *notify_ops;
> > > >         /* for protocol internal use */
> > > >         void *perf_priv;
> > > > @@ -291,6 +353,7 @@ struct scmi_handle {
> > > >         void *power_priv;
> > > >         void *sensor_priv;
> > > >         void *reset_priv;
> > > > +       void *voltage_priv;
> > > >         void *notify_priv;
> > > >         void *system_priv;
> > > >  };
> > > > @@ -303,6 +366,7 @@ enum scmi_std_protocol {
> > > >         SCMI_PROTOCOL_CLOCK = 0x14,
> > > >         SCMI_PROTOCOL_SENSOR = 0x15,
> > > >         SCMI_PROTOCOL_RESET = 0x16,
> > > > +       SCMI_PROTOCOL_VOLTAGE = 0x17,
> > > >  };
> > > >
> > > >  enum scmi_system_events {
> > > > --
> > > > 2.17.1
> > > >

Patch

diff --git a/drivers/firmware/arm_scmi/Makefile b/drivers/firmware/arm_scmi/Makefile
index bc0d54f8e861..6a2ef63306d6 100644
--- a/drivers/firmware/arm_scmi/Makefile
+++ b/drivers/firmware/arm_scmi/Makefile
@@ -4,7 +4,7 @@  scmi-driver-y = driver.o notify.o
 scmi-transport-y = shmem.o
 scmi-transport-$(CONFIG_MAILBOX) += mailbox.o
 scmi-transport-$(CONFIG_HAVE_ARM_SMCCC_DISCOVERY) += smc.o
-scmi-protocols-y = base.o clock.o perf.o power.o reset.o sensors.o system.o
+scmi-protocols-y = base.o clock.o perf.o power.o reset.o sensors.o system.o voltage.o
 scmi-module-objs := $(scmi-bus-y) $(scmi-driver-y) $(scmi-protocols-y) \
 		    $(scmi-transport-y)
 obj-$(CONFIG_ARM_SCMI_PROTOCOL) += scmi-module.o
diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
index 65063fa948d4..c0fb45e7c3e8 100644
--- a/drivers/firmware/arm_scmi/common.h
+++ b/drivers/firmware/arm_scmi/common.h
@@ -169,6 +169,7 @@  DECLARE_SCMI_REGISTER_UNREGISTER(perf);
 DECLARE_SCMI_REGISTER_UNREGISTER(power);
 DECLARE_SCMI_REGISTER_UNREGISTER(reset);
 DECLARE_SCMI_REGISTER_UNREGISTER(sensors);
+DECLARE_SCMI_REGISTER_UNREGISTER(voltage);
 DECLARE_SCMI_REGISTER_UNREGISTER(system);
 
 #define DEFINE_SCMI_PROTOCOL_REGISTER_UNREGISTER(id, name) \
diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 3dfd8b6a0ebf..ada35e63feae 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -946,6 +946,7 @@  static int __init scmi_driver_init(void)
 	scmi_power_register();
 	scmi_reset_register();
 	scmi_sensors_register();
+	scmi_voltage_register();
 	scmi_system_register();
 
 	return platform_driver_register(&scmi_driver);
@@ -961,6 +962,7 @@  static void __exit scmi_driver_exit(void)
 	scmi_power_unregister();
 	scmi_reset_unregister();
 	scmi_sensors_unregister();
+	scmi_voltage_unregister();
 	scmi_system_unregister();
 
 	platform_driver_unregister(&scmi_driver);
diff --git a/drivers/firmware/arm_scmi/voltage.c b/drivers/firmware/arm_scmi/voltage.c
new file mode 100644
index 000000000000..2c5a3c8b8649
--- /dev/null
+++ b/drivers/firmware/arm_scmi/voltage.c
@@ -0,0 +1,398 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * System Control and Management Interface (SCMI) Voltage Protocol
+ *
+ * Copyright (C) 2020 ARM Ltd.
+ */
+
+#include <linux/scmi_protocol.h>
+
+#include "common.h"
+
+#define VOLTAGE_DOMS_NUM_MASK		GENMASK(15, 0)
+#define REMAINING_LEVELS_MASK		GENMASK(31, 16)
+#define RETURNED_LEVELS_MASK		GENMASK(11, 0)
+
+enum scmi_voltage_protocol_cmd {
+	VOLTAGE_DOMAIN_ATTRIBUTES = 0x3,
+	VOLTAGE_DESCRIBE_LEVELS = 0x4,
+	VOLTAGE_CONFIG_SET = 0x5,
+	VOLTAGE_CONFIG_GET = 0x6,
+	VOLTAGE_LEVEL_SET = 0x7,
+	VOLTAGE_LEVEL_GET = 0x8,
+};
+
+struct scmi_msg_resp_protocol_attributes {
+	__le32 attr;
+#define NUM_VOLTAGE_DOMAINS(x)	(u16)(FIELD_GET(VOLTAGE_DOMS_NUM_MASK, (x)))
+};
+
+struct scmi_msg_resp_domain_attributes {
+	__le32 attr;
+	u8 name[SCMI_MAX_STR_SIZE];
+};
+
+struct scmi_msg_cmd_describe_levels {
+	__le32 domain_id;
+	__le32 level_index;
+};
+
+struct scmi_msg_resp_describe_levels {
+	__le32 flags;
+#define NUM_REMAINING_LEVELS(f)	(u16)(FIELD_GET(REMAINING_LEVELS_MASK, (f)))
+#define NUM_RETURNED_LEVELS(f)	(u16)(FIELD_GET(RETURNED_LEVELS_MASK, (f)))
+#define SUPPORTS_SEGMENTED_LEVELS(f)	((f) & BIT(12))
+	__le32 voltage[];
+};
+
+struct scmi_msg_cmd_config_set {
+	__le32 domain_id;
+	__le32 config;
+};
+
+struct scmi_msg_cmd_level_set {
+	__le32 domain_id;
+	__le32 flags;
+	__le32 voltage_level;
+};
+
+struct voltage_info {
+	u32 version;
+	u16 num_domains;
+	struct scmi_voltage_info **domains;
+};
+
+static int scmi_protocol_attributes_get(const struct scmi_handle *handle,
+					struct voltage_info *vinfo)
+{
+	int ret;
+	struct scmi_xfer *t;
+	struct scmi_msg_resp_protocol_attributes *resp;
+
+	ret = scmi_xfer_get_init(handle, PROTOCOL_ATTRIBUTES,
+				 SCMI_PROTOCOL_VOLTAGE, 0, sizeof(*resp), &t);
+	if (ret)
+		return ret;
+
+	resp = t->rx.buf;
+	ret = scmi_do_xfer(handle, t);
+	if (!ret)
+		vinfo->num_domains =
+			NUM_VOLTAGE_DOMAINS(le32_to_cpu(resp->attr));
+
+	scmi_xfer_put(handle, t);
+	return ret;
+}
+
+static inline int scmi_init_voltage_levels(struct device *dev,
+					   struct scmi_voltage_info *v,
+					   u32 flags, u32 num_returned,
+					   u32 num_remaining)
+{
+	bool segmented;
+	u32 num_levels;
+
+	segmented = SUPPORTS_SEGMENTED_LEVELS(flags);
+	num_levels = num_returned + num_remaining;
+	/*
+	 * segmented levels entries are represented by a single triplet
+	 * returned all in one go.
+	 */
+	if (!num_levels ||
+	    (segmented && (num_remaining || num_returned != 3))) {
+		dev_err(dev,
+			"Invalid level descriptor(%d/%d/%d) for voltage dom %d\n",
+			num_levels, num_returned, num_remaining, v->id);
+		return -EINVAL;
+	}
+
+	v->levels_uv = devm_kcalloc(dev, num_levels, sizeof(u32), GFP_KERNEL);
+	if (!v->levels_uv)
+		return -ENOMEM;
+
+	v->num_levels = num_levels;
+	v->segmented = segmented;
+
+	return 0;
+}
+
+static int scmi_voltage_descriptors_get(const struct scmi_handle *handle,
+					struct voltage_info *vinfo)
+{
+	int ret, dom;
+	struct scmi_xfer *td, *tl;
+	struct device *dev = handle->dev;
+	struct scmi_msg_resp_domain_attributes *resp_dom;
+	struct scmi_msg_resp_describe_levels *resp_levels;
+
+	ret = scmi_xfer_get_init(handle, VOLTAGE_DOMAIN_ATTRIBUTES,
+				 SCMI_PROTOCOL_VOLTAGE, sizeof(__le32),
+				 sizeof(*resp_dom), &td);
+	if (ret)
+		return ret;
+	resp_dom = td->rx.buf;
+
+	ret = scmi_xfer_get_init(handle, VOLTAGE_DESCRIBE_LEVELS,
+				 SCMI_PROTOCOL_VOLTAGE, sizeof(__le64), 0, &tl);
+	if (ret)
+		goto outd;
+	resp_levels = tl->rx.buf;
+
+	for (dom = 0; dom < vinfo->num_domains; dom++) {
+		u32 desc_index = 0;
+		u16 num_returned = 0, num_remaining = 0;
+		struct scmi_msg_cmd_describe_levels *cmd;
+		struct scmi_voltage_info *v;
+
+		/* Retrieve domain attributes at first ... */
+		put_unaligned_le32(dom, td->tx.buf);
+		ret = scmi_do_xfer(handle, td);
+		/* Skip domain on comms error */
+		if (ret)
+			continue;
+
+		v = devm_kzalloc(dev, sizeof(*v), GFP_KERNEL);
+		if (!v) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		v->id = dom;
+		v->attributes = le32_to_cpu(resp_dom->attr);
+		strlcpy(v->name, resp_dom->name, SCMI_MAX_STR_SIZE);
+
+		cmd = tl->tx.buf;
+		/* ...then retrieve domain levels descriptions */
+		do {
+			u32 flags;
+			int cnt;
+
+			cmd->domain_id = cpu_to_le32(v->id);
+			cmd->level_index = desc_index;
+			ret = scmi_do_xfer(handle, tl);
+			if (ret)
+				break;
+
+			flags = le32_to_cpu(resp_levels->flags);
+			num_returned = NUM_RETURNED_LEVELS(flags);
+			num_remaining = NUM_REMAINING_LEVELS(flags);
+
+			/* Allocate space for num_levels if not already done */
+			if (!v->num_levels) {
+				ret = scmi_init_voltage_levels(dev, v, flags,
+							       num_returned,
+							       num_remaining);
+				if (ret)
+					break;
+			}
+
+			if (desc_index + num_returned > v->num_levels) {
+				dev_err(handle->dev,
+					"No. of voltage levels can't exceed %d\n",
+					v->num_levels);
+				ret = -EINVAL;
+				break;
+			}
+
+			for (cnt = 0; cnt < num_returned; cnt++) {
+				s32 val;
+
+				val =
+				    (s32)le32_to_cpu(resp_levels->voltage[cnt]);
+				v->levels_uv[desc_index + cnt] = val;
+				if (val < 0)
+					v->negative_volts_allowed = true;
+			}
+
+			desc_index += num_returned;
+
+			scmi_reset_rx_to_maxsz(handle, tl);
+			/* check both to avoid infinite loop due to buggy fw */
+		} while (num_returned && num_remaining);
+
+		/*
+		 * Bail out only on memory errors, just skip domain and free
+		 * on any other error.
+		 */
+		if (!ret) {
+			vinfo->domains[dom] = v;
+		} else if (ret != -ENOMEM) {
+			devm_kfree(dev, v->levels_uv);
+			devm_kfree(dev, v);
+		} else {
+			break;
+		}
+
+		scmi_reset_rx_to_maxsz(handle, td);
+	}
+
+	scmi_xfer_put(handle, tl);
+outd:
+	scmi_xfer_put(handle, td);
+
+	return ret;
+}
+
+static int __scmi_voltage_get_u32(const struct scmi_handle *handle,
+				  u8 cmd_id, u32 domain_id, u32 *value)
+{
+	int ret;
+	struct scmi_xfer *t;
+	struct voltage_info *vinfo = handle->voltage_priv;
+
+	if (domain_id >= vinfo->num_domains)
+		return -EINVAL;
+
+	ret = scmi_xfer_get_init(handle, cmd_id,
+				 SCMI_PROTOCOL_VOLTAGE,
+				 sizeof(__le32), 0, &t);
+	if (ret)
+		return ret;
+
+	put_unaligned_le32(domain_id, t->tx.buf);
+	ret = scmi_do_xfer(handle, t);
+	if (!ret)
+		*value = get_unaligned_le32(t->rx.buf);
+
+	scmi_xfer_put(handle, t);
+	return ret;
+}
+
+static int scmi_voltage_config_set(const struct scmi_handle *handle,
+				   u32 domain_id, u32 config)
+{
+	int ret;
+	struct scmi_xfer *t;
+	struct voltage_info *vinfo = handle->voltage_priv;
+	struct scmi_msg_cmd_config_set *cmd;
+
+	if (domain_id >= vinfo->num_domains)
+		return -EINVAL;
+
+	ret = scmi_xfer_get_init(handle, VOLTAGE_CONFIG_SET,
+				 SCMI_PROTOCOL_VOLTAGE,
+				 sizeof(*cmd), 0, &t);
+	if (ret)
+		return ret;
+
+	cmd = t->tx.buf;
+	cmd->domain_id = cpu_to_le32(domain_id);
+	cmd->config = cpu_to_le32(config & GENMASK(3, 0));
+
+	ret = scmi_do_xfer(handle, t);
+
+	scmi_xfer_put(handle, t);
+	return ret;
+}
+
+static int scmi_voltage_config_get(const struct scmi_handle *handle,
+				   u32 domain_id, u32 *config)
+{
+	return __scmi_voltage_get_u32(handle, VOLTAGE_CONFIG_GET,
+				      domain_id, config);
+}
+
+static int scmi_voltage_level_set(const struct scmi_handle *handle,
+				  u32 domain_id, u32 flags, s32 volt_uV)
+{
+	int ret;
+	struct scmi_xfer *t;
+	struct voltage_info *vinfo = handle->voltage_priv;
+	struct scmi_msg_cmd_level_set *cmd;
+
+	if (domain_id >= vinfo->num_domains)
+		return -EINVAL;
+
+	ret = scmi_xfer_get_init(handle, VOLTAGE_LEVEL_SET,
+				 SCMI_PROTOCOL_VOLTAGE,
+				 sizeof(*cmd), 0, &t);
+	if (ret)
+		return ret;
+
+	cmd = t->tx.buf;
+	cmd->domain_id = cpu_to_le32(domain_id);
+	cmd->flags = cpu_to_le32(flags);
+	cmd->voltage_level = cpu_to_le32(volt_uV);
+
+	ret = scmi_do_xfer(handle, t);
+
+	scmi_xfer_put(handle, t);
+	return ret;
+}
+
+static int scmi_voltage_level_get(const struct scmi_handle *handle,
+				  u32 domain_id, s32 *volt_uV)
+{
+	return __scmi_voltage_get_u32(handle, VOLTAGE_LEVEL_GET,
+				      domain_id, (u32 *)volt_uV);
+}
+
+static const struct scmi_voltage_info * __must_check
+scmi_voltage_info_get(const struct scmi_handle *handle, u32 domain_id)
+{
+	struct voltage_info *vinfo = handle->voltage_priv;
+
+	if (domain_id >= vinfo->num_domains)
+		return NULL;
+
+	return vinfo->domains[domain_id];
+}
+
+static int scmi_voltage_domains_num_get(const struct scmi_handle *handle)
+{
+	struct voltage_info *vinfo = handle->voltage_priv;
+
+	return vinfo->num_domains;
+}
+
+static struct scmi_voltage_ops voltage_ops = {
+	.num_domains_get = scmi_voltage_domains_num_get,
+	.info_get = scmi_voltage_info_get,
+	.config_set = scmi_voltage_config_set,
+	.config_get = scmi_voltage_config_get,
+	.level_set = scmi_voltage_level_set,
+	.level_get = scmi_voltage_level_get,
+};
+
+static int scmi_voltage_protocol_init(struct scmi_handle *handle)
+{
+	int ret;
+	u32 version;
+	struct voltage_info *vinfo;
+
+	ret = scmi_version_get(handle, SCMI_PROTOCOL_VOLTAGE, &version);
+	if (ret)
+		return ret;
+
+	dev_dbg(handle->dev, "Voltage Version %d.%d\n",
+		PROTOCOL_REV_MAJOR(version), PROTOCOL_REV_MINOR(version));
+
+	vinfo = devm_kzalloc(handle->dev, sizeof(*vinfo), GFP_KERNEL);
+	if (!vinfo)
+		return -ENOMEM;
+	vinfo->version = version;
+
+	ret = scmi_protocol_attributes_get(handle, vinfo);
+	if (ret)
+		return ret;
+
+	if (vinfo->num_domains) {
+		vinfo->domains = devm_kcalloc(handle->dev, vinfo->num_domains,
+					      sizeof(vinfo->domains),
+					      GFP_KERNEL);
+		if (!vinfo->domains)
+			return -ENOMEM;
+		ret = scmi_voltage_descriptors_get(handle, vinfo);
+		if (ret)
+			return ret;
+	} else {
+		dev_warn(handle->dev, "No Voltage domains found.\n");
+	}
+
+	handle->voltage_ops = &voltage_ops;
+	handle->voltage_priv = vinfo;
+
+	return 0;
+}
+
+DEFINE_SCMI_PROTOCOL_REGISTER_UNREGISTER(SCMI_PROTOCOL_VOLTAGE, voltage)
diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
index 9cd312a1ff92..181fdebc2793 100644
--- a/include/linux/scmi_protocol.h
+++ b/include/linux/scmi_protocol.h
@@ -209,6 +209,64 @@  struct scmi_reset_ops {
 	int (*deassert)(const struct scmi_handle *handle, u32 domain);
 };
 
+/**
+ * struct scmi_voltage_info - describe one available SCMI Voltage Domain
+ *
+ * @id: the domain ID as advertised by the platform
+ * @segmented: defines the layout of the entries of array @levels_uv.
+ *	       - when True the entries are to be interpreted as triplets,
+ *	         each defining a segment representing a range of equally
+ *	         space voltages: <lowest_volts>, <highest_volt>, <step_uV>
+ *	       - when False the entries simply represent a single discrete
+ *	         supported voltage level
+ * @negative_volts_allowed: True if any of the entries of @levels_uv represent
+ *			    a negative voltage.
+ * @attributes: represents Voltage Domain advertised attributes
+ * @name: name assigned to the Voltage Domain by platform
+ * @num_levels: number of total entries in @levels_uv.
+ * @levels_uv: array of entries describing the available voltage levels for
+ *	       this domain.
+ */
+struct scmi_voltage_info {
+	unsigned int id;
+	bool segmented;
+#define SCMI_VOLTAGE_SEGMENT_LOW	0
+#define SCMI_VOLTAGE_SEGMENT_HIGH	1
+#define SCMI_VOLTAGE_SEGMENT_STEP	2
+	bool negative_volts_allowed;
+	unsigned int attributes;
+	char name[SCMI_MAX_STR_SIZE];
+	unsigned int num_levels;
+	int *levels_uv;
+};
+
+/**
+ * struct scmi_voltage_ops - represents the various operations provided
+ * by SCMI Voltage Protocol
+ *
+ * @num_domains_get: get the count of voltage domains provided by SCMI
+ * @info_get: get the information of the specified domain
+ * @config_set: set the config for the specified domain
+ * @config_get: get the config of the specified domain
+ * @level_set: set the voltage level for the specified domain
+ * @level_get: get the voltage level of the specified domain
+ */
+struct scmi_voltage_ops {
+	int (*num_domains_get)(const struct scmi_handle *handle);
+	const struct scmi_voltage_info __must_check *(*info_get)
+		(const struct scmi_handle *handle, u32 domain_id);
+	int (*config_set)(const struct scmi_handle *handle, u32 domain_id,
+			  u32 config);
+#define	SCMI_VOLTAGE_ARCH_STATE_OFF		0x0
+#define	SCMI_VOLTAGE_ARCH_STATE_ON		0x7
+	int (*config_get)(const struct scmi_handle *handle, u32 domain_id,
+			  u32 *config);
+	int (*level_set)(const struct scmi_handle *handle, u32 domain_id,
+			 u32 flags, s32 volt_uV);
+	int (*level_get)(const struct scmi_handle *handle, u32 domain_id,
+			 s32 *volt_uV);
+};
+
 /**
  * struct scmi_notify_ops  - represents notifications' operations provided by
  * SCMI core
@@ -262,6 +320,7 @@  struct scmi_notify_ops {
  * @clk_ops: pointer to set of clock protocol operations
  * @sensor_ops: pointer to set of sensor protocol operations
  * @reset_ops: pointer to set of reset protocol operations
+ * @voltage_ops: pointer to set of voltage protocol operations
  * @notify_ops: pointer to set of notifications related operations
  * @perf_priv: pointer to private data structure specific to performance
  *	protocol(for internal use only)
@@ -273,6 +332,8 @@  struct scmi_notify_ops {
  *	protocol(for internal use only)
  * @reset_priv: pointer to private data structure specific to reset
  *	protocol(for internal use only)
+ * @voltage_priv: pointer to private data structure specific to voltage
+ *	protocol(for internal use only)
  * @notify_priv: pointer to private data structure specific to notifications
  *	(for internal use only)
  */
@@ -284,6 +345,7 @@  struct scmi_handle {
 	const struct scmi_power_ops *power_ops;
 	const struct scmi_sensor_ops *sensor_ops;
 	const struct scmi_reset_ops *reset_ops;
+	const struct scmi_voltage_ops *voltage_ops;
 	const struct scmi_notify_ops *notify_ops;
 	/* for protocol internal use */
 	void *perf_priv;
@@ -291,6 +353,7 @@  struct scmi_handle {
 	void *power_priv;
 	void *sensor_priv;
 	void *reset_priv;
+	void *voltage_priv;
 	void *notify_priv;
 	void *system_priv;
 };
@@ -303,6 +366,7 @@  enum scmi_std_protocol {
 	SCMI_PROTOCOL_CLOCK = 0x14,
 	SCMI_PROTOCOL_SENSOR = 0x15,
 	SCMI_PROTOCOL_RESET = 0x16,
+	SCMI_PROTOCOL_VOLTAGE = 0x17,
 };
 
 enum scmi_system_events {