diff mbox series

[v6,36/37] firmware: arm_scmi: add protocol modularization support

Message ID 20210202221555.41167-37-cristian.marussi@arm.com (mailing list archive)
State New, archived
Headers show
Series SCMI vendor protocols and modularization | expand

Commit Message

Cristian Marussi Feb. 2, 2021, 10:15 p.m. UTC
Extend SCMI protocols accounting mechanism to address possible module
usage and add the support to possibly define new protocols as loadable
modules.

Keep Standard protocols built into the SCMI core.

Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
---
 drivers/firmware/arm_scmi/base.c    |  2 ++
 drivers/firmware/arm_scmi/bus.c     | 11 ++++++++++-
 drivers/firmware/arm_scmi/clock.c   |  2 ++
 drivers/firmware/arm_scmi/common.h  |  4 ++++
 drivers/firmware/arm_scmi/driver.c  |  5 ++++-
 drivers/firmware/arm_scmi/perf.c    |  2 ++
 drivers/firmware/arm_scmi/power.c   |  2 ++
 drivers/firmware/arm_scmi/reset.c   |  2 ++
 drivers/firmware/arm_scmi/sensors.c |  2 ++
 drivers/firmware/arm_scmi/system.c  |  2 ++
 include/linux/scmi_protocol.h       | 12 ++++++++++++
 11 files changed, 44 insertions(+), 2 deletions(-)

Comments

Sudeep Holla March 8, 2021, 7:34 a.m. UTC | #1
On Tue, Feb 02, 2021 at 10:15:54PM +0000, Cristian Marussi wrote:
> Extend SCMI protocols accounting mechanism to address possible module
> usage and add the support to possibly define new protocols as loadable
> modules.
>
> Keep Standard protocols built into the SCMI core.
>

The changes look good, however without any users I am bit hesitant to add
this yet. However if you think it is hard to maintain it outside the tree
until first user gets merged, we can merge provided we test this every
release. Let me know your thoughts.

Also any comment from users requesting this would be useful.

--
Regards,
Sudeep
Cristian Marussi March 9, 2021, 8:04 a.m. UTC | #2
Hi Sudeep,

On Mon, Mar 08, 2021 at 07:34:25AM +0000, Sudeep Holla wrote:
> On Tue, Feb 02, 2021 at 10:15:54PM +0000, Cristian Marussi wrote:
> > Extend SCMI protocols accounting mechanism to address possible module
> > usage and add the support to possibly define new protocols as loadable
> > modules.
> >
> > Keep Standard protocols built into the SCMI core.
> >
> 
> The changes look good, however without any users I am bit hesitant to add
> this yet. However if you think it is hard to maintain it outside the tree
> until first user gets merged, we can merge provided we test this every
> release. Let me know your thoughts.
> 

On one side this series aimed not only at simplifying the API exposed to
the drivers/protocols but also to unify such API betweeen custom and standard
protocols and drivers, so that whatever custom proto and driver you wrote, you
are anyway going to exercise the same API and triggering the same internals
as the standard protos, so to avoid the issue of having to expose/support
an API not used by anyone (still)....

...on the other side, indeed, you are right that this specific thin patch
WON'T be really tested/exercised indeed until a custon protocol module is
upstreamed...if ever.

For me it's fine to test it every cycle with my custom dummy protocol,
and maybe it could be an incentive for partners to post finally upstream
their protos if all the support is already there in the mainline (I know,
I'm a dreamer :D), but better would be as a future alternative (not for
this series though) to enable (in some well guarded/controlled form) the
optional modularization of core standard protocols too (also to possibly
comply with ACK extreme modularization policies...), so that this patch
would be constantly exercised by our std protocol too.

But I have not really a strong opinion on this, if you want to keep this
out and merge only once a real custom proto appears or once we modularize
the core standard protocols (in a controlled manner as said), it's fine
for me too.

Thanks

Cristian

> Also any comment from users requesting this would be useful.
> 

> --
> Regards,
> Sudeep
diff mbox series

Patch

diff --git a/drivers/firmware/arm_scmi/base.c b/drivers/firmware/arm_scmi/base.c
index f2d10c5a55ae..b70d741f8465 100644
--- a/drivers/firmware/arm_scmi/base.c
+++ b/drivers/firmware/arm_scmi/base.c
@@ -7,6 +7,7 @@ 
 
 #define pr_fmt(fmt) "SCMI Notifications BASE - " fmt
 
+#include <linux/module.h>
 #include <linux/scmi_protocol.h>
 
 #include "common.h"
@@ -373,6 +374,7 @@  static int scmi_base_protocol_init(const struct scmi_protocol_handle *ph)
 
 static const struct scmi_protocol scmi_base = {
 	.id = SCMI_PROTOCOL_BASE,
+	.owner = NULL,
 	.init_instance = &scmi_base_protocol_init,
 	.ops = NULL,
 	.events = &base_protocol_events,
diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
index 9fbf618b9c4b..88e5057f4e85 100644
--- a/drivers/firmware/arm_scmi/bus.c
+++ b/drivers/firmware/arm_scmi/bus.c
@@ -56,7 +56,7 @@  const struct scmi_protocol *scmi_get_protocol(int protocol_id)
 	const struct scmi_protocol *proto;
 
 	proto = idr_find(&scmi_available_protocols, protocol_id);
-	if (!proto) {
+	if (!proto || !try_module_get(proto->owner)) {
 		pr_warn("SCMI Protocol 0x%x not found!\n", protocol_id);
 		return NULL;
 	}
@@ -66,6 +66,15 @@  const struct scmi_protocol *scmi_get_protocol(int protocol_id)
 	return proto;
 }
 
+void scmi_put_protocol(int protocol_id)
+{
+	const struct scmi_protocol *proto;
+
+	proto = idr_find(&scmi_available_protocols, protocol_id);
+	if (proto)
+		module_put(proto->owner);
+}
+
 static int scmi_dev_probe(struct device *dev)
 {
 	struct scmi_driver *scmi_drv = to_scmi_driver(dev->driver);
diff --git a/drivers/firmware/arm_scmi/clock.c b/drivers/firmware/arm_scmi/clock.c
index a0a6593f464f..bd364d3a56d2 100644
--- a/drivers/firmware/arm_scmi/clock.c
+++ b/drivers/firmware/arm_scmi/clock.c
@@ -5,6 +5,7 @@ 
  * Copyright (C) 2018-2020 ARM Ltd.
  */
 
+#include <linux/module.h>
 #include <linux/sort.h>
 
 #include "common.h"
@@ -367,6 +368,7 @@  static int scmi_clock_protocol_init(const struct scmi_protocol_handle *ph)
 
 static const struct scmi_protocol scmi_clock = {
 	.id = SCMI_PROTOCOL_CLOCK,
+	.owner = THIS_MODULE,
 	.init_instance = &scmi_clock_protocol_init,
 	.ops = &clk_proto_ops,
 };
diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
index 5fb64182610a..1e2046c61d43 100644
--- a/drivers/firmware/arm_scmi/common.h
+++ b/drivers/firmware/arm_scmi/common.h
@@ -14,6 +14,7 @@ 
 #include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/kernel.h>
+#include <linux/module.h>
 #include <linux/scmi_protocol.h>
 #include <linux/types.h>
 
@@ -214,6 +215,7 @@  typedef int (*scmi_prot_init_ph_fn_t)(const struct scmi_protocol_handle *);
 /**
  * struct scmi_protocol  - Protocol descriptor
  * @id: Protocol ID.
+ * @owner: Module reference if any.
  * @init_instance: Mandatory protocol initialization function.
  * @deinit_instance: Optional protocol de-initialization function.
  * @ops: Optional reference to the operations provided by the protocol and
@@ -222,6 +224,7 @@  typedef int (*scmi_prot_init_ph_fn_t)(const struct scmi_protocol_handle *);
  */
 struct scmi_protocol {
 	const u8				id;
+	struct module				*owner;
 	const scmi_prot_init_ph_fn_t		init_instance;
 	const scmi_prot_init_ph_fn_t		deinit_instance;
 	const void				*ops;
@@ -255,6 +258,7 @@  void __exit scmi_##name##_unregister(void) \
 }
 
 const struct scmi_protocol *scmi_get_protocol(int protocol_id);
+void scmi_put_protocol(int protocol_id);
 
 int scmi_acquire_protocol(const struct scmi_handle *handle, u8 protocol_id);
 void scmi_release_protocol(const struct scmi_handle *handle, u8 protocol_id);
diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 159d3fa2b9b6..dcdfd94b47f7 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -677,7 +677,7 @@  scmi_get_protocol_instance(const struct scmi_handle *handle, u8 protocol_id)
 		/* Fail if protocol not registered on bus */
 		proto = scmi_get_protocol(protocol_id);
 		if (!proto) {
-			ret = -ENODEV;
+			ret = -EPROBE_DEFER;
 			goto out;
 		}
 
@@ -722,6 +722,7 @@  scmi_get_protocol_instance(const struct scmi_handle *handle, u8 protocol_id)
 	return pi;
 
 clean:
+	scmi_put_protocol(protocol_id);
 	devres_release_group(handle->dev, gid);
 out:
 	mutex_unlock(&info->protocols_mtx);
@@ -772,6 +773,8 @@  void scmi_release_protocol(const struct scmi_handle *handle, u8 protocol_id)
 
 		idr_remove(&info->protocols, protocol_id);
 
+		scmi_put_protocol(protocol_id);
+
 		devres_release_group(handle->dev, gid);
 		dev_dbg(handle->dev, "De-Initialized protocol: 0x%X\n",
 			protocol_id);
diff --git a/drivers/firmware/arm_scmi/perf.c b/drivers/firmware/arm_scmi/perf.c
index c87a390463d9..f9146429789e 100644
--- a/drivers/firmware/arm_scmi/perf.c
+++ b/drivers/firmware/arm_scmi/perf.c
@@ -11,6 +11,7 @@ 
 #include <linux/of.h>
 #include <linux/io.h>
 #include <linux/io-64-nonatomic-hi-lo.h>
+#include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/pm_opp.h>
 #include <linux/scmi_protocol.h>
@@ -909,6 +910,7 @@  static int scmi_perf_protocol_init(const struct scmi_protocol_handle *ph)
 
 static const struct scmi_protocol scmi_perf = {
 	.id = SCMI_PROTOCOL_PERF,
+	.owner = THIS_MODULE,
 	.init_instance = &scmi_perf_protocol_init,
 	.ops = &perf_proto_ops,
 	.events = &perf_protocol_events,
diff --git a/drivers/firmware/arm_scmi/power.c b/drivers/firmware/arm_scmi/power.c
index 3e453d9bcbc8..70d366ed37e6 100644
--- a/drivers/firmware/arm_scmi/power.c
+++ b/drivers/firmware/arm_scmi/power.c
@@ -7,6 +7,7 @@ 
 
 #define pr_fmt(fmt) "SCMI Notifications POWER - " fmt
 
+#include <linux/module.h>
 #include <linux/scmi_protocol.h>
 
 #include "common.h"
@@ -312,6 +313,7 @@  static int scmi_power_protocol_init(const struct scmi_protocol_handle *ph)
 
 static const struct scmi_protocol scmi_power = {
 	.id = SCMI_PROTOCOL_POWER,
+	.owner = THIS_MODULE,
 	.init_instance = &scmi_power_protocol_init,
 	.ops = &power_proto_ops,
 	.events = &power_protocol_events,
diff --git a/drivers/firmware/arm_scmi/reset.c b/drivers/firmware/arm_scmi/reset.c
index bd28d4e9664d..b26686dd8526 100644
--- a/drivers/firmware/arm_scmi/reset.c
+++ b/drivers/firmware/arm_scmi/reset.c
@@ -7,6 +7,7 @@ 
 
 #define pr_fmt(fmt) "SCMI Notifications RESET - " fmt
 
+#include <linux/module.h>
 #include <linux/scmi_protocol.h>
 
 #include "common.h"
@@ -324,6 +325,7 @@  static int scmi_reset_protocol_init(const struct scmi_protocol_handle *ph)
 
 static const struct scmi_protocol scmi_reset = {
 	.id = SCMI_PROTOCOL_RESET,
+	.owner = THIS_MODULE,
 	.init_instance = &scmi_reset_protocol_init,
 	.ops = &reset_proto_ops,
 	.events = &reset_protocol_events,
diff --git a/drivers/firmware/arm_scmi/sensors.c b/drivers/firmware/arm_scmi/sensors.c
index edc08d9f8daa..903fcdb57d4a 100644
--- a/drivers/firmware/arm_scmi/sensors.c
+++ b/drivers/firmware/arm_scmi/sensors.c
@@ -8,6 +8,7 @@ 
 #define pr_fmt(fmt) "SCMI Notifications SENSOR - " fmt
 
 #include <linux/bitfield.h>
+#include <linux/module.h>
 #include <linux/scmi_protocol.h>
 
 #include "common.h"
@@ -990,6 +991,7 @@  static int scmi_sensors_protocol_init(const struct scmi_protocol_handle *ph)
 
 static const struct scmi_protocol scmi_sensors = {
 	.id = SCMI_PROTOCOL_SENSOR,
+	.owner = THIS_MODULE,
 	.init_instance = &scmi_sensors_protocol_init,
 	.ops = &sensor_proto_ops,
 	.events = &sensor_protocol_events,
diff --git a/drivers/firmware/arm_scmi/system.c b/drivers/firmware/arm_scmi/system.c
index 97ad20a51d72..a68bad27688f 100644
--- a/drivers/firmware/arm_scmi/system.c
+++ b/drivers/firmware/arm_scmi/system.c
@@ -7,6 +7,7 @@ 
 
 #define pr_fmt(fmt) "SCMI Notifications SYSTEM - " fmt
 
+#include <linux/module.h>
 #include <linux/scmi_protocol.h>
 
 #include "common.h"
@@ -130,6 +131,7 @@  static int scmi_system_protocol_init(const struct scmi_protocol_handle *ph)
 
 static const struct scmi_protocol scmi_system = {
 	.id = SCMI_PROTOCOL_SYSTEM,
+	.owner = THIS_MODULE,
 	.init_instance = &scmi_system_protocol_init,
 	.ops = NULL,
 	.events = &system_protocol_events,
diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
index 51ec4dc4fd6a..fb8c8f16a49b 100644
--- a/include/linux/scmi_protocol.h
+++ b/include/linux/scmi_protocol.h
@@ -709,6 +709,18 @@  static inline void scmi_driver_unregister(struct scmi_driver *driver) {}
 #define module_scmi_driver(__scmi_driver)	\
 	module_driver(__scmi_driver, scmi_register, scmi_unregister)
 
+/**
+ * module_scmi_protocol() - Helper macro for registering a scmi protocol
+ * @__scmi_protocol: scmi_protocol structure
+ *
+ * Helper macro for scmi drivers to set up proper module init / exit
+ * functions.  Replaces module_init() and module_exit() and keeps people from
+ * printing pointless things to the kernel log when their driver is loaded.
+ */
+#define module_scmi_protocol(__scmi_protocol)	\
+	module_driver(__scmi_protocol,		\
+		      scmi_protocol_register, scmi_protocol_unregister)
+
 struct scmi_protocol;
 int scmi_protocol_register(const struct scmi_protocol *proto);
 void scmi_protocol_unregister(const struct scmi_protocol *proto);