[v4,03/11] soc: renesas: rcar-sysc: Add DT support for SYSC PM domains

Commit Message

Geert Uytterhoeven April 7, 2016, 12:20 p.m. UTC

Populate the SYSC PM domains from DT, based on the presence of a device
node for the System Controller. The actual power area hiearchy, and
features of specific areas are obtained from tables in the C code.

The SYSCIER and SYSCIMR register values are derived from the power areas
present, which will help to get rid of the hardcoded values in R-Car H1
and R-Car Gen2 platform code later.

Initialization is done in two phases:
  1. SYSC initialization and setup of power areas containing CPUs or
     SCUs is done from an early_initcall(), to make sure these PM
     Domains are initialized before secondary CPU bringup,
  2. Setup of the always-on power area (which is basically an alias for
     the CPG/MSSR or CPG/MSTP Clock Domain), and of I/O power areas is
     done from builtin_platform_driver_probe(), when the Clock Domain is
     available.

Signed-off-by: Geert Uytterhoeven <[e-mail]>
---
v4:
  - Make sure not to clear reserved SYSCIMR bits that were set before,
  - Make the always-on power area implicit and always present, and an
    alias of the existing SoC's Clock Domain. This makes the number of
    power areas a compile-time constant, and allows to drop PD_ALWAYS_ON
    and some checks.
  - Split initialization in two phases,
  - Document that ARM cores are controlled by PSCI on R-Car Gen3
    (although the underlying CPG/APMU hardware is the same as on Gen2),
  - Minor improvements (double evaluation, unused parameter, debug
    message consolidation),

v3:
  - Drop check for CONFIG_PM_GENERIC_DOMAINS, which is now always
    enabled on R-Car SoCs,
  - Create PM Domains from hierarchy in C data instead of DT,
  - Initialize SYSCIER early, as SYSC needs the interrupt sources to be
    enabled to control power,
  - Mask all SYSC interrupt sources for the CPU,
  - Add support for an "always-on" domain,
  - Use early_initcall() instead of core_initcall(),
  - Do not power up CPU power areas during initialization, as this is
    handled later (directly or indirectly) by the SMP code,

v2:
  - Add missing definitions for SYSC_PWR_CA15_CPU and SYSC_PWR_CA7_CPU,
  - Add R-Car H3 (r8a7795) support,
  - Drop tests for CONFIG_ARCH_SHMOBILE_LEGACY,
  - Add missing break statements in rcar_sysc_pwr_on_off(),
  - Add missing calls to of_node_put() in error paths,
  - Fix build if CONFIG_PM=n,
  - Update compatible values,
  - Update copyright.
---
 drivers/soc/renesas/rcar-sysc.c | 261 +++++++++++++++++++++++++++++++++++++++-
 drivers/soc/renesas/rcar-sysc.h |  52 ++++++++
 2 files changed, 312 insertions(+), 1 deletion(-)
 create mode 100644 drivers/soc/renesas/rcar-sysc.h

Comments

Laurent Pinchart April 9, 2016, 7:50 p.m. UTC | #1

Hi Geert,

Thank you for the patch.

On Thursday 07 Apr 2016 14:20:20 Geert Uytterhoeven wrote:
> Populate the SYSC PM domains from DT, based on the presence of a device
> node for the System Controller. The actual power area hiearchy, and
> features of specific areas are obtained from tables in the C code.
> 
> The SYSCIER and SYSCIMR register values are derived from the power areas
> present, which will help to get rid of the hardcoded values in R-Car H1
> and R-Car Gen2 platform code later.
> 
> Initialization is done in two phases:
>   1. SYSC initialization and setup of power areas containing CPUs or
>      SCUs is done from an early_initcall(), to make sure these PM
>      Domains are initialized before secondary CPU bringup,
>   2. Setup of the always-on power area (which is basically an alias for
>      the CPG/MSSR or CPG/MSTP Clock Domain), and of I/O power areas is
>      done from builtin_platform_driver_probe(), when the Clock Domain is
>      available.
> 
> Signed-off-by: Geert Uytterhoeven <[e-mail]>
> ---
> v4:
>   - Make sure not to clear reserved SYSCIMR bits that were set before,
>   - Make the always-on power area implicit and always present, and an
>     alias of the existing SoC's Clock Domain. This makes the number of
>     power areas a compile-time constant, and allows to drop PD_ALWAYS_ON
>     and some checks.
>   - Split initialization in two phases,
>   - Document that ARM cores are controlled by PSCI on R-Car Gen3
>     (although the underlying CPG/APMU hardware is the same as on Gen2),
>   - Minor improvements (double evaluation, unused parameter, debug
>     message consolidation),
> 
> v3:
>   - Drop check for CONFIG_PM_GENERIC_DOMAINS, which is now always
>     enabled on R-Car SoCs,
>   - Create PM Domains from hierarchy in C data instead of DT,
>   - Initialize SYSCIER early, as SYSC needs the interrupt sources to be
>     enabled to control power,
>   - Mask all SYSC interrupt sources for the CPU,
>   - Add support for an "always-on" domain,
>   - Use early_initcall() instead of core_initcall(),
>   - Do not power up CPU power areas during initialization, as this is
>     handled later (directly or indirectly) by the SMP code,
> 
> v2:
>   - Add missing definitions for SYSC_PWR_CA15_CPU and SYSC_PWR_CA7_CPU,
>   - Add R-Car H3 (r8a7795) support,
>   - Drop tests for CONFIG_ARCH_SHMOBILE_LEGACY,
>   - Add missing break statements in rcar_sysc_pwr_on_off(),
>   - Add missing calls to of_node_put() in error paths,
>   - Fix build if CONFIG_PM=n,
>   - Update compatible values,
>   - Update copyright.
> ---
>  drivers/soc/renesas/rcar-sysc.c | 261 ++++++++++++++++++++++++++++++++++++-
>  drivers/soc/renesas/rcar-sysc.h |  52 ++++++++
>  2 files changed, 312 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/soc/renesas/rcar-sysc.h
> 
> diff --git a/drivers/soc/renesas/rcar-sysc.c
> b/drivers/soc/renesas/rcar-sysc.c index 9ba5fd15c53bf9b9..3cb19b599cee4ee5
> 100644
> --- a/drivers/soc/renesas/rcar-sysc.c
> +++ b/drivers/soc/renesas/rcar-sysc.c
> @@ -2,6 +2,7 @@
>   * R-Car SYSC Power management support
>   *
>   * Copyright (C) 2014  Magnus Damm
> + * Copyright (C) 2015-2016 Glider bvba
>   *
>   * This file is subject to the terms and conditions of the GNU General
> Public * License.  See the file "COPYING" in the main directory of this
> archive
> @@ -11,10 +12,17 @@
>  #include <linux/delay.h>
>  #include <linux/err.h>
>  #include <linux/mm.h>
> +#include <linux/of_address.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_domain.h>
> +#include <linux/slab.h>
>  #include <linux/spinlock.h>
>  #include <linux/io.h>
>  #include <linux/soc/renesas/rcar-sysc.h>
> 
> +#include "rcar-sysc.h"
> +
>  /* SYSC Common */
>  #define SYSCSR			0x00	/* SYSC Status Register */
>  #define SYSCISR			0x04	/* Interrupt Status Register */
> @@ -29,7 +37,8 @@
>  /*
>   * Power Control Register Offsets inside the register block for each domain
> * Note: The "CR" registers for ARM cores exist on H1 only
> - *       Use WFI to power off, CPG/APMU to resume ARM cores on R-Car Gen2
> + *	 Use WFI to power off, CPG/APMU to resume ARM cores on R-Car Gen2
> + *	 Use PSCI on R-Car Gen3
>   */
>  #define PWRSR_OFFS		0x00	/* Power Status Register */
>  #define PWROFFCR_OFFS		0x04	/* Power Shutoff Control Register */
> @@ -48,6 +57,8 @@
>  #define SYSCISR_RETRIES		1000
>  #define SYSCISR_DELAY_US	1
> 
> +#define RCAR_PD_ALWAYS_ON	32	/* Always-on power area */
> +
>  static void __iomem *rcar_sysc_base;
>  static DEFINE_SPINLOCK(rcar_sysc_lock); /* SMP CPUs + I/O devices */
> 
> @@ -162,3 +173,251 @@ void __iomem *rcar_sysc_init(phys_addr_t base)
> 
>  	return rcar_sysc_base;
>  }
> +
> +struct rcar_sysc_pd {
> +	struct generic_pm_domain genpd;
> +	struct rcar_sysc_ch ch;
> +	unsigned int flags;
> +	char name[0];
> +};
> +
> +static inline struct rcar_sysc_pd *to_rcar_pd(struct generic_pm_domain *d)
> +{
> +	return container_of(d, struct rcar_sysc_pd, genpd);
> +}
> +
> +static bool rcar_sysc_active_wakeup(struct device *dev)
> +{
> +	return true;
> +}
> +
> +static int rcar_sysc_pd_power_off(struct generic_pm_domain *genpd)
> +{
> +	struct rcar_sysc_pd *pd = to_rcar_pd(genpd);
> +
> +	pr_debug("%s: %s\n", __func__, genpd->name);
> +
> +	if (pd->flags & PD_NO_CR) {
> +		pr_debug("%s: Cannot control %s\n", __func__, genpd->name);
> +		return -EBUSY;
> +	}
> +
> +	if (pd->flags & PD_BUSY) {
> +		pr_debug("%s: %s busy\n", __func__, genpd->name);
> +		return -EBUSY;
> +	}
> +
> +	return rcar_sysc_power_down(&pd->ch);
> +}
> +
> +static int rcar_sysc_pd_power_on(struct generic_pm_domain *genpd)
> +{
> +	struct rcar_sysc_pd *pd = to_rcar_pd(genpd);
> +
> +	pr_debug("%s: %s\n", __func__, genpd->name);
> +
> +	if (pd->flags & PD_NO_CR) {
> +		pr_debug("%s: Cannot control %s\n", __func__, genpd->name);
> +		return 0;
> +	}
> +
> +	return rcar_sysc_power_up(&pd->ch);
> +}
> +
> +static void __init rcar_sysc_pd_setup(struct rcar_sysc_pd *pd)
> +{
> +	struct generic_pm_domain *genpd = &pd->genpd;
> +	const char *name = pd->genpd.name;
> +	struct dev_power_governor *gov = &simple_qos_governor;
> +
> +	if (pd->flags & PD_CPU) {
> +		/*
> +		 * This domain contains a CPU core and therefore it should
> +		 * only be turned off if the CPU is not in use.
> +		 */
> +		pr_debug("PM domain %s contains %s\n", name, "CPU");
> +		pd->flags |= PD_BUSY;
> +		gov = &pm_domain_always_on_gov;
> +	} else if (pd->flags & PD_SCU) {
> +		/*
> +		 * This domain contains an SCU and cache-controller, and
> +		 * therefore it should only be turned off if the CPU cores are
> +		 * not in use.
> +		 */
> +		pr_debug("PM domain %s contains %s\n", name, "SCU");
> +		pd->flags |= PD_BUSY;
> +		gov = &pm_domain_always_on_gov;
> +	}
> +
> +	pm_genpd_init(genpd, gov, false);
> +	genpd->dev_ops.active_wakeup = rcar_sysc_active_wakeup;
> +	genpd->power_off = rcar_sysc_pd_power_off;
> +	genpd->power_on = rcar_sysc_pd_power_on;
> +
> +	if (pd->flags & PD_CPU) {
> +		/* Skip CPUs (handled by SMP code) */
> +		pr_debug("%s: Not touching %s\n", __func__, genpd->name);
> +		return;
> +	}
> +
> +	if (!rcar_sysc_power_is_off(&pd->ch)) {
> +		pr_debug("%s: %s is already powered\n", __func__, genpd->name);
> +		return;
> +	}
> +
> +	rcar_sysc_power_up(&pd->ch);
> +}
> +
> +static const struct of_device_id rcar_sysc_matches[] = {
> +	{ /* sentinel */ }
> +};
> +
> +struct rcar_pm_domains {
> +	struct genpd_onecell_data onecell_data;
> +	struct generic_pm_domain *domains[RCAR_PD_ALWAYS_ON + 1];
> +};
> +
> +static struct genpd_onecell_data *rcar_sysc_onecell_data;
> +
> +static int __init rcar_sysc_pd_init(const struct rcar_sysc_info *info,
> +				    bool early)
> +{
> +	struct generic_pm_domain **domains = rcar_sysc_onecell_data->domains;
> +	unsigned int i;
> +
> +	for (i = 0; i < info->num_areas; i++) {
> +		const struct rcar_sysc_area *area = &info->areas[i];
> +		struct rcar_sysc_pd *pd;
> +
> +		/* Skip non-CPU/SCU domains during phase 1 */
> +		if (early && !(area->flags & (PD_CPU | PD_SCU)))
> +			continue;
> +
> +		/* Tie CPU/SCU domains to always-on domain during phase 2 * */
> +		if (!early && (area->flags & (PD_CPU | PD_SCU))) {
> +			if (area->parent < 0)
> +				pm_genpd_add_subdomain(
> +					domains[RCAR_PD_ALWAYS_ON],
> +					domains[area->isr_bit]);
> +			continue;
> +		}
> +
> +		pd = kzalloc(sizeof(*pd) + strlen(area->name) + 1, GFP_KERNEL);
> +		if (!pd)
> +			return -ENOMEM;
> +
> +		strcpy(pd->name, area->name);
> +		pd->genpd.name = pd->name;
> +		pd->ch.chan_offs = area->chan_offs;
> +		pd->ch.chan_bit = area->chan_bit;
> +		pd->ch.isr_bit = area->isr_bit;
> +		pd->flags = area->flags;
> +
> +		rcar_sysc_pd_setup(pd);
> +		if (area->parent >= 0)
> +			pm_genpd_add_subdomain(domains[area->parent],
> +					       &pd->genpd);
> +		else if (domains[RCAR_PD_ALWAYS_ON])
> +			pm_genpd_add_subdomain(domains[RCAR_PD_ALWAYS_ON],
> +					       &pd->genpd);
> +
> +		domains[area->isr_bit] = &pd->genpd;
> +	}
> +
> +	return 0;
> +}
> +
> +/*
> + * Initialization phase 1, including setup of CPU and SCU domains
> + */
> +static int __init rcar_sysc_early(void)
> +{
> +	const struct rcar_sysc_info *info;
> +	const struct of_device_id *match;
> +	struct rcar_pm_domains *domains;
> +	struct device_node *np;
> +	u32 syscier, syscimr;
> +	void __iomem *base;
> +	unsigned int i;
> +	int error;
> +
> +	np = of_find_matching_node_and_match(NULL, rcar_sysc_matches, &match);
> +	if (!np)
> +		return -ENODEV;
> +
> +	info = match->data;
> +
> +	base = of_iomap(np, 0);
> +	if (!base) {
> +		pr_warn("%s: Cannot map regs\n", np->full_name);
> +		error = -ENOMEM;
> +		goto out_put;
> +	}
> +
> +	rcar_sysc_base = base;
> +
> +	domains = kzalloc(sizeof(*domains), GFP_KERNEL);
> +	if (!domains) {
> +		error = -ENOMEM;
> +		goto out_put;

You might want to iounmap() when cleaning up.

> +	}
> +
> +	domains->onecell_data.domains = domains->domains;
> +	domains->onecell_data.num_domains = ARRAY_SIZE(domains->domains);
> +
> +	/*
> +	 * SYSC needs all interrupt sources enabled to control power.
> +	 */
> +	for (i = 0, syscier = 0; i < info->num_areas; i++)
> +		syscier |= BIT(info->areas[i].isr_bit);
> +	pr_debug("%s: syscier = 0x%08x\n", np->full_name, syscier);
> +	iowrite32(syscier, base + SYSCIER);
> +
> +	/*
> +	 * Mask all interrupt sources to prevent the CPU from receiving them.
> +	 * Make sure not to clear reserved bits that were set before.
> +	 */
> +	syscimr = ioread32(base + SYSCIMR);
> +	syscimr |= syscier;
> +	pr_debug("%s: syscimr = 0x%08x\n", np->full_name, syscimr);
> +	iowrite32(syscimr, base + SYSCIMR);

Should you mask the interrupt sources before enabling them in SYSCIER ?

> +	rcar_sysc_onecell_data = &domains->onecell_data;
> +
> +	error = rcar_sysc_pd_init(info, true);
> +	if (error)
> +		goto out_put;
> +
> +	of_genpd_add_provider_onecell(np, &domains->onecell_data);
> +
> +out_put:
> +	of_node_put(np);
> +	return error;
> +}
> +early_initcall(rcar_sysc_early);
> +
> +
> +/*
> + * Initialization phase 2, including setup of always-on and I/O domains
> + */
> +static int __init rcar_sysc_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +
> +	if (!rcar_sysc_onecell_data)
> +		return -ENODEV;
> +
> +	rcar_sysc_onecell_data->domains[RCAR_PD_ALWAYS_ON] =
> +		pd_to_genpd(dev->pm_domain);

This part, or rather the power-domains = <&cpg_clocks>; property in the SYSC 
DT node, bothers me. I don't think the DT property really describes the 
hardware. I like your " clk: renesas: cpg-mssr: Export 
cpg_mssr_{at,de}tach_dev()" approach better.

> +	return rcar_sysc_pd_init(of_device_get_match_data(dev), false);
> +}
> +
> +static struct platform_driver rcar_sysc_driver = {
> +	.driver = {
> +		.name = "rcar-sysc",
> +		.of_match_table = rcar_sysc_matches,
> +	},
> +};
> +
> +builtin_platform_driver_probe(rcar_sysc_driver, rcar_sysc_probe);
> diff --git a/drivers/soc/renesas/rcar-sysc.h
> b/drivers/soc/renesas/rcar-sysc.h new file mode 100644
> index 0000000000000000..4aeb3541227a5456
> --- /dev/null
> +++ b/drivers/soc/renesas/rcar-sysc.h
> @@ -0,0 +1,52 @@
> +/*
> + * Renesas R-Car System Controller
> + *
> + * Copyright (C) 2016 Glider bvba
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; version 2 of the License.
> + */
> +#ifndef __SOC_RENESAS_RCAR_SYSC_H__
> +#define __SOC_RENESAS_RCAR_SYSC_H__
> +
> +#include <linux/types.h>
> +
> +
> +/*
> + * Power Domain flags
> + */
> +#define PD_CPU		BIT(0)	/* Area contains main CPU core */
> +#define PD_SCU		BIT(1)	/* Area contains SCU and L2 cache */
> +#define PD_NO_CR	BIT(2)	/* Area lacks PWR{ON,OFF}CR registers */
> +
> +#define PD_BUSY		BIT(3)	/* Busy, for internal use only */
> +
> +#define PD_CPU_CR	PD_CPU		  /* CPU area has CR (R-Car H1) */
> +#define PD_CPU_NOCR	PD_CPU | PD_NO_CR /* CPU area lacks CR (R-Car Gen2/3)

I'd enclose PD_CPU | PD_NO_CR in parentheses.

> */ +
> +
> +/*
> + * Description of a Power Area
> + */
> +
> +struct rcar_sysc_area {
> +	const char *name;
> +	u16 chan_offs;		/* Offset of PWRSR register for this area */
> +	u8 chan_bit;		/* Bit in PWR* (except for PWRUP in PWRSR) */
> +	u8 isr_bit;		/* Bit in SYSCI*R */
> +	int parent;		/* -1 if none (i.e. always-on) */
> +	unsigned int flags;	/* See PD_* */
> +};
> +
> +
> +/*
> + * SoC-specific Power Area Description
> + */
> +
> +struct rcar_sysc_info {
> +	const struct rcar_sysc_area *areas;
> +	unsigned int num_areas;
> +};
> +
> +#endif /* __SOC_RENESAS_RCAR_SYSC_H__ */

Geert Uytterhoeven April 11, 2016, 9:39 a.m. UTC | #2

Hi Laurent,

Thanks for your comments!

On Sat, Apr 9, 2016 at 9:50 PM, Laurent Pinchart
<[e-mail]> wrote:
> On Thursday 07 Apr 2016 14:20:20 Geert Uytterhoeven wrote:
>> Populate the SYSC PM domains from DT, based on the presence of a device
>> node for the System Controller. The actual power area hiearchy, and
>> features of specific areas are obtained from tables in the C code.
>>
>> The SYSCIER and SYSCIMR register values are derived from the power areas
>> present, which will help to get rid of the hardcoded values in R-Car H1
>> and R-Car Gen2 platform code later.
>>
>> Initialization is done in two phases:
>>   1. SYSC initialization and setup of power areas containing CPUs or
>>      SCUs is done from an early_initcall(), to make sure these PM
>>      Domains are initialized before secondary CPU bringup,
>>   2. Setup of the always-on power area (which is basically an alias for
>>      the CPG/MSSR or CPG/MSTP Clock Domain), and of I/O power areas is
>>      done from builtin_platform_driver_probe(), when the Clock Domain is
>>      available.

>> --- a/drivers/soc/renesas/rcar-sysc.c
>> +++ b/drivers/soc/renesas/rcar-sysc.c

>> +/*
>> + * Initialization phase 1, including setup of CPU and SCU domains
>> + */
>> +static int __init rcar_sysc_early(void)
>> +{
>> +     const struct rcar_sysc_info *info;
>> +     const struct of_device_id *match;
>> +     struct rcar_pm_domains *domains;
>> +     struct device_node *np;
>> +     u32 syscier, syscimr;
>> +     void __iomem *base;
>> +     unsigned int i;
>> +     int error;
>> +
>> +     np = of_find_matching_node_and_match(NULL, rcar_sysc_matches, &match);
>> +     if (!np)
>> +             return -ENODEV;
>> +
>> +     info = match->data;
>> +
>> +     base = of_iomap(np, 0);
>> +     if (!base) {
>> +             pr_warn("%s: Cannot map regs\n", np->full_name);
>> +             error = -ENOMEM;
>> +             goto out_put;
>> +     }
>> +
>> +     rcar_sysc_base = base;
>> +
>> +     domains = kzalloc(sizeof(*domains), GFP_KERNEL);
>> +     if (!domains) {
>> +             error = -ENOMEM;
>> +             goto out_put;
>
> You might want to iounmap() when cleaning up.

That's a bit tricky. The R-Car H1 and H2 platform code may still call
rcar_sysc_power_*() if initialization fails here, which relies on
rcar_sysc_base pointing to the mapped registers.
So until that code is cleaned up (I have local patches), I would like to keep
it this way.

>> +     /*
>> +      * Mask all interrupt sources to prevent the CPU from receiving them.
>> +      * Make sure not to clear reserved bits that were set before.
>> +      */
>> +     syscimr = ioread32(base + SYSCIMR);
>> +     syscimr |= syscier;
>> +     pr_debug("%s: syscimr = 0x%08x\n", np->full_name, syscimr);
>> +     iowrite32(syscimr, base + SYSCIMR);
>
> Should you mask the interrupt sources before enabling them in SYSCIER ?

It doesn't matter much, as they're disabled at the GIC level anyway.
Note that the current platform code doesn't mask them at all.

I'll change the order, though.

>> +/*
>> + * Initialization phase 2, including setup of always-on and I/O domains
>> + */
>> +static int __init rcar_sysc_probe(struct platform_device *pdev)
>> +{
>> +     struct device *dev = &pdev->dev;
>> +
>> +     if (!rcar_sysc_onecell_data)
>> +             return -ENODEV;
>> +
>> +     rcar_sysc_onecell_data->domains[RCAR_PD_ALWAYS_ON] =
>> +             pd_to_genpd(dev->pm_domain);
>
> This part, or rather the power-domains = <&cpg_clocks>; property in the SYSC
> DT node, bothers me. I don't think the DT property really describes the
> hardware. I like your " clk: renesas: cpg-mssr: Export
> cpg_mssr_{at,de}tach_dev()" approach better.

I had two issues with the other approach:
  1. It required keeping a static pointer to the cpg_mssr_clk_domain structure,
  2. The SYSC driver had to call the CPG/MSSR driver directly.

The second issue made it complicated to support the SYSC "always-on" PM Domain
on R-Car H1 and Gen2, as these SoCs (currently) don't use the CPG/MSSR driver,
but the CPG/MSTP driver, so the SYSC driver has to differentiate to call into
the right Clock Domain driver. Migrating these SoCs over to CPG/MSSR and
preserving backwards compatibility is even more complicated.

Hence the need to express the relationship in DT.

Would you be more comfortable using a custom property instead of the
"power-domains" property to link SYSC to CPG in DT?
E.g.:

    renesas,cpg = <&cpg_clocks>;

The "Connected module" subsection of the "System Controller (SYSC)" section of
the User's Manual does list the "Clock Pulse Generator (CPG)" as a connected
module, so that would describe the hardware.

Then I can call of_genpd_get_from_provider() to get a pointer to the Clock
Domain, and call its .attach/detach() methods directly from
rcar_sysc_{at,de}tach_dev(), without walking the parent PM Domains.

>> --- /dev/null
>> +++ b/drivers/soc/renesas/rcar-sysc.h

>> +/*
>> + * Power Domain flags
>> + */
>> +#define PD_CPU               BIT(0)  /* Area contains main CPU core */
>> +#define PD_SCU               BIT(1)  /* Area contains SCU and L2 cache */
>> +#define PD_NO_CR     BIT(2)  /* Area lacks PWR{ON,OFF}CR registers */
>> +
>> +#define PD_BUSY              BIT(3)  /* Busy, for internal use only */
>> +
>> +#define PD_CPU_CR    PD_CPU            /* CPU area has CR (R-Car H1) */
>> +#define PD_CPU_NOCR  PD_CPU | PD_NO_CR /* CPU area lacks CR (R-Car Gen2/3)
>
> I'd enclose PD_CPU | PD_NO_CR in parentheses.

I choose not to do so, as it would make the comment no longer fit on the line.
As the define is used in tables only, the risk of incorrect operator precedence
is very low.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [e-mail]

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Patch

diff --git a/drivers/soc/renesas/rcar-sysc.c b/drivers/soc/renesas/rcar-sysc.c
index 9ba5fd15c53bf9b9..3cb19b599cee4ee5 100644
--- a/drivers/soc/renesas/rcar-sysc.c
+++ b/drivers/soc/renesas/rcar-sysc.c
@@ -2,6 +2,7 @@ 
  * R-Car SYSC Power management support
  *
  * Copyright (C) 2014  Magnus Damm
+ * Copyright (C) 2015-2016 Glider bvba
  *
  * This file is subject to the terms and conditions of the GNU General Public
  * License.  See the file "COPYING" in the main directory of this archive
@@ -11,10 +12,17 @@ 
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/mm.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_domain.h>
+#include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/io.h>
 #include <linux/soc/renesas/rcar-sysc.h>
 
+#include "rcar-sysc.h"
+
 /* SYSC Common */
 #define SYSCSR			0x00	/* SYSC Status Register */
 #define SYSCISR			0x04	/* Interrupt Status Register */
@@ -29,7 +37,8 @@ 
 /*
  * Power Control Register Offsets inside the register block for each domain
  * Note: The "CR" registers for ARM cores exist on H1 only
- *       Use WFI to power off, CPG/APMU to resume ARM cores on R-Car Gen2
+ *	 Use WFI to power off, CPG/APMU to resume ARM cores on R-Car Gen2
+ *	 Use PSCI on R-Car Gen3
  */
 #define PWRSR_OFFS		0x00	/* Power Status Register */
 #define PWROFFCR_OFFS		0x04	/* Power Shutoff Control Register */
@@ -48,6 +57,8 @@ 
 #define SYSCISR_RETRIES		1000
 #define SYSCISR_DELAY_US	1
 
+#define RCAR_PD_ALWAYS_ON	32	/* Always-on power area */
+
 static void __iomem *rcar_sysc_base;
 static DEFINE_SPINLOCK(rcar_sysc_lock); /* SMP CPUs + I/O devices */
 
@@ -162,3 +173,251 @@  void __iomem *rcar_sysc_init(phys_addr_t base)
 
 	return rcar_sysc_base;
 }
+
+struct rcar_sysc_pd {
+	struct generic_pm_domain genpd;
+	struct rcar_sysc_ch ch;
+	unsigned int flags;
+	char name[0];
+};
+
+static inline struct rcar_sysc_pd *to_rcar_pd(struct generic_pm_domain *d)
+{
+	return container_of(d, struct rcar_sysc_pd, genpd);
+}
+
+static bool rcar_sysc_active_wakeup(struct device *dev)
+{
+	return true;
+}
+
+static int rcar_sysc_pd_power_off(struct generic_pm_domain *genpd)
+{
+	struct rcar_sysc_pd *pd = to_rcar_pd(genpd);
+
+	pr_debug("%s: %s\n", __func__, genpd->name);
+
+	if (pd->flags & PD_NO_CR) {
+		pr_debug("%s: Cannot control %s\n", __func__, genpd->name);
+		return -EBUSY;
+	}
+
+	if (pd->flags & PD_BUSY) {
+		pr_debug("%s: %s busy\n", __func__, genpd->name);
+		return -EBUSY;
+	}
+
+	return rcar_sysc_power_down(&pd->ch);
+}
+
+static int rcar_sysc_pd_power_on(struct generic_pm_domain *genpd)
+{
+	struct rcar_sysc_pd *pd = to_rcar_pd(genpd);
+
+	pr_debug("%s: %s\n", __func__, genpd->name);
+
+	if (pd->flags & PD_NO_CR) {
+		pr_debug("%s: Cannot control %s\n", __func__, genpd->name);
+		return 0;
+	}
+
+	return rcar_sysc_power_up(&pd->ch);
+}
+
+static void __init rcar_sysc_pd_setup(struct rcar_sysc_pd *pd)
+{
+	struct generic_pm_domain *genpd = &pd->genpd;
+	const char *name = pd->genpd.name;
+	struct dev_power_governor *gov = &simple_qos_governor;
+
+	if (pd->flags & PD_CPU) {
+		/*
+		 * This domain contains a CPU core and therefore it should
+		 * only be turned off if the CPU is not in use.
+		 */
+		pr_debug("PM domain %s contains %s\n", name, "CPU");
+		pd->flags |= PD_BUSY;
+		gov = &pm_domain_always_on_gov;
+	} else if (pd->flags & PD_SCU) {
+		/*
+		 * This domain contains an SCU and cache-controller, and
+		 * therefore it should only be turned off if the CPU cores are
+		 * not in use.
+		 */
+		pr_debug("PM domain %s contains %s\n", name, "SCU");
+		pd->flags |= PD_BUSY;
+		gov = &pm_domain_always_on_gov;
+	}
+
+	pm_genpd_init(genpd, gov, false);
+	genpd->dev_ops.active_wakeup = rcar_sysc_active_wakeup;
+	genpd->power_off = rcar_sysc_pd_power_off;
+	genpd->power_on = rcar_sysc_pd_power_on;
+
+	if (pd->flags & PD_CPU) {
+		/* Skip CPUs (handled by SMP code) */
+		pr_debug("%s: Not touching %s\n", __func__, genpd->name);
+		return;
+	}
+
+	if (!rcar_sysc_power_is_off(&pd->ch)) {
+		pr_debug("%s: %s is already powered\n", __func__, genpd->name);
+		return;
+	}
+
+	rcar_sysc_power_up(&pd->ch);
+}
+
+static const struct of_device_id rcar_sysc_matches[] = {
+	{ /* sentinel */ }
+};
+
+struct rcar_pm_domains {
+	struct genpd_onecell_data onecell_data;
+	struct generic_pm_domain *domains[RCAR_PD_ALWAYS_ON + 1];
+};
+
+static struct genpd_onecell_data *rcar_sysc_onecell_data;
+
+static int __init rcar_sysc_pd_init(const struct rcar_sysc_info *info,
+				    bool early)
+{
+	struct generic_pm_domain **domains = rcar_sysc_onecell_data->domains;
+	unsigned int i;
+
+	for (i = 0; i < info->num_areas; i++) {
+		const struct rcar_sysc_area *area = &info->areas[i];
+		struct rcar_sysc_pd *pd;
+
+		/* Skip non-CPU/SCU domains during phase 1 */
+		if (early && !(area->flags & (PD_CPU | PD_SCU)))
+			continue;
+
+		/* Tie CPU/SCU domains to always-on domain during phase 2 * */
+		if (!early && (area->flags & (PD_CPU | PD_SCU))) {
+			if (area->parent < 0)
+				pm_genpd_add_subdomain(
+					domains[RCAR_PD_ALWAYS_ON],
+					domains[area->isr_bit]);
+			continue;
+		}
+
+		pd = kzalloc(sizeof(*pd) + strlen(area->name) + 1, GFP_KERNEL);
+		if (!pd)
+			return -ENOMEM;
+
+		strcpy(pd->name, area->name);
+		pd->genpd.name = pd->name;
+		pd->ch.chan_offs = area->chan_offs;
+		pd->ch.chan_bit = area->chan_bit;
+		pd->ch.isr_bit = area->isr_bit;
+		pd->flags = area->flags;
+
+		rcar_sysc_pd_setup(pd);
+		if (area->parent >= 0)
+			pm_genpd_add_subdomain(domains[area->parent],
+					       &pd->genpd);
+		else if (domains[RCAR_PD_ALWAYS_ON])
+			pm_genpd_add_subdomain(domains[RCAR_PD_ALWAYS_ON],
+					       &pd->genpd);
+
+		domains[area->isr_bit] = &pd->genpd;
+	}
+
+	return 0;
+}
+
+/*
+ * Initialization phase 1, including setup of CPU and SCU domains
+ */
+static int __init rcar_sysc_early(void)
+{
+	const struct rcar_sysc_info *info;
+	const struct of_device_id *match;
+	struct rcar_pm_domains *domains;
+	struct device_node *np;
+	u32 syscier, syscimr;
+	void __iomem *base;
+	unsigned int i;
+	int error;
+
+	np = of_find_matching_node_and_match(NULL, rcar_sysc_matches, &match);
+	if (!np)
+		return -ENODEV;
+
+	info = match->data;
+
+	base = of_iomap(np, 0);
+	if (!base) {
+		pr_warn("%s: Cannot map regs\n", np->full_name);
+		error = -ENOMEM;
+		goto out_put;
+	}
+
+	rcar_sysc_base = base;
+
+	domains = kzalloc(sizeof(*domains), GFP_KERNEL);
+	if (!domains) {
+		error = -ENOMEM;
+		goto out_put;
+	}
+
+	domains->onecell_data.domains = domains->domains;
+	domains->onecell_data.num_domains = ARRAY_SIZE(domains->domains);
+
+	/*
+	 * SYSC needs all interrupt sources enabled to control power.
+	 */
+	for (i = 0, syscier = 0; i < info->num_areas; i++)
+		syscier |= BIT(info->areas[i].isr_bit);
+	pr_debug("%s: syscier = 0x%08x\n", np->full_name, syscier);
+	iowrite32(syscier, base + SYSCIER);
+
+	/*
+	 * Mask all interrupt sources to prevent the CPU from receiving them.
+	 * Make sure not to clear reserved bits that were set before.
+	 */
+	syscimr = ioread32(base + SYSCIMR);
+	syscimr |= syscier;
+	pr_debug("%s: syscimr = 0x%08x\n", np->full_name, syscimr);
+	iowrite32(syscimr, base + SYSCIMR);
+
+	rcar_sysc_onecell_data = &domains->onecell_data;
+
+	error = rcar_sysc_pd_init(info, true);
+	if (error)
+		goto out_put;
+
+	of_genpd_add_provider_onecell(np, &domains->onecell_data);
+
+out_put:
+	of_node_put(np);
+	return error;
+}
+early_initcall(rcar_sysc_early);
+
+
+/*
+ * Initialization phase 2, including setup of always-on and I/O domains
+ */
+static int __init rcar_sysc_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+
+	if (!rcar_sysc_onecell_data)
+		return -ENODEV;
+
+	rcar_sysc_onecell_data->domains[RCAR_PD_ALWAYS_ON] =
+		pd_to_genpd(dev->pm_domain);
+
+	return rcar_sysc_pd_init(of_device_get_match_data(dev), false);
+}
+
+static struct platform_driver rcar_sysc_driver = {
+	.driver = {
+		.name = "rcar-sysc",
+		.of_match_table = rcar_sysc_matches,
+	},
+};
+
+builtin_platform_driver_probe(rcar_sysc_driver, rcar_sysc_probe);
diff --git a/drivers/soc/renesas/rcar-sysc.h b/drivers/soc/renesas/rcar-sysc.h
new file mode 100644
index 0000000000000000..4aeb3541227a5456
--- /dev/null
+++ b/drivers/soc/renesas/rcar-sysc.h
@@ -0,0 +1,52 @@ 
+/*
+ * Renesas R-Car System Controller
+ *
+ * Copyright (C) 2016 Glider bvba
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ */
+#ifndef __SOC_RENESAS_RCAR_SYSC_H__
+#define __SOC_RENESAS_RCAR_SYSC_H__
+
+#include <linux/types.h>
+
+
+/*
+ * Power Domain flags
+ */
+#define PD_CPU		BIT(0)	/* Area contains main CPU core */
+#define PD_SCU		BIT(1)	/* Area contains SCU and L2 cache */
+#define PD_NO_CR	BIT(2)	/* Area lacks PWR{ON,OFF}CR registers */
+
+#define PD_BUSY		BIT(3)	/* Busy, for internal use only */
+
+#define PD_CPU_CR	PD_CPU		  /* CPU area has CR (R-Car H1) */
+#define PD_CPU_NOCR	PD_CPU | PD_NO_CR /* CPU area lacks CR (R-Car Gen2/3) */
+
+
+/*
+ * Description of a Power Area
+ */
+
+struct rcar_sysc_area {
+	const char *name;
+	u16 chan_offs;		/* Offset of PWRSR register for this area */
+	u8 chan_bit;		/* Bit in PWR* (except for PWRUP in PWRSR) */
+	u8 isr_bit;		/* Bit in SYSCI*R */
+	int parent;		/* -1 if none (i.e. always-on) */
+	unsigned int flags;	/* See PD_* */
+};
+
+
+/*
+ * SoC-specific Power Area Description
+ */
+
+struct rcar_sysc_info {
+	const struct rcar_sysc_area *areas;
+	unsigned int num_areas;
+};
+
+#endif /* __SOC_RENESAS_RCAR_SYSC_H__ */