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From:   Cristian Marussi <cristian.marussi@arm.com>
To:     linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc:     sudeep.holla@arm.com, lukasz.luba@arm.com,
        james.quinlan@broadcom.com, Jonathan.Cameron@Huawei.com,
        f.fainelli@gmail.com, etienne.carriere@linaro.org,
        thara.gopinath@linaro.org, vincent.guittot@linaro.org,
        souvik.chakravarty@arm.com, cristian.marussi@arm.com
Subject: [PATCH v2 8/8] firmware: arm_scmi: add protocol modularization support
Date:   Wed, 28 Oct 2020 20:29:14 +0000
Message-Id: <20201028202914.43662-9-cristian.marussi@arm.com>
In-Reply-To: <20201028202914.43662-1-cristian.marussi@arm.com>
References: <20201028202914.43662-1-cristian.marussi@arm.com>
Precedence: bulk

Extend SCMI protocols accounting 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(-)

diff --git a/drivers/firmware/arm_scmi/base.c b/drivers/firmware/arm_scmi/base.c
index 745e475e6cc4..e66e23d07d82 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 = &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 25b191cfefc1..b152860f6c99 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 00041dcb4d06..06ed45c0002a 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 = &scmi_clock_protocol_init,
 	.ops = &clk_ops,
 };
diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
index 9ae0e4133f31..d3f62f85ea18 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>
 
@@ -216,6 +217,7 @@ typedef int (*scmi_prot_init_fn_t)(const struct scmi_protocol_handle *);
 /**
  * struct scmi_protocol  - Protocol descriptor
  * @id: Protocol ID.
+ * @owner: Module reference if any.
  * @init: Mandatory protocol initialization function.
  * @deinit: Optional protocol de-initialization function.
  * @ops: Optional reference to the operations provided by the protocol and
@@ -224,6 +226,7 @@ typedef int (*scmi_prot_init_fn_t)(const struct scmi_protocol_handle *);
  */
 struct scmi_protocol {
 	const u8				id;
+	struct module				*owner;
 	const scmi_prot_init_fn_t		init;
 	const scmi_prot_init_fn_t		deinit;
 	const void				*ops;
@@ -256,6 +259,7 @@ 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 d6a975992136..077152fd5fc3 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 c1d0664aaf4a..66e0d2364ea6 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>
@@ -900,6 +901,7 @@ 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 = &scmi_perf_protocol_init,
 	.ops = &perf_ops,
 	.events = &perf_protocol_events,
diff --git a/drivers/firmware/arm_scmi/power.c b/drivers/firmware/arm_scmi/power.c
index d9ce794d0299..819d948eb034 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"
@@ -310,6 +311,7 @@ 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 = &scmi_power_protocol_init,
 	.ops = &power_ops,
 	.events = &power_protocol_events,
diff --git a/drivers/firmware/arm_scmi/reset.c b/drivers/firmware/arm_scmi/reset.c
index a183518baf18..9f408070b70d 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 = &scmi_reset_protocol_init,
 	.ops = &reset_ops,
 	.events = &reset_protocol_events,
diff --git a/drivers/firmware/arm_scmi/sensors.c b/drivers/firmware/arm_scmi/sensors.c
index a74a7938cd78..170d97f09d91 100644
--- a/drivers/firmware/arm_scmi/sensors.c
+++ b/drivers/firmware/arm_scmi/sensors.c
@@ -7,6 +7,7 @@
 
 #define pr_fmt(fmt) "SCMI Notifications SENSOR - " fmt
 
+#include <linux/module.h>
 #include <linux/scmi_protocol.h>
 
 #include "common.h"
@@ -375,6 +376,7 @@ 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 = &scmi_sensors_protocol_init,
 	.ops = &sensor_ops,
 	.events = &sensor_protocol_events,
diff --git a/drivers/firmware/arm_scmi/system.c b/drivers/firmware/arm_scmi/system.c
index 23365ef334bf..13bd223feb84 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"
@@ -129,6 +130,7 @@ 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 = &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 66625aedd3a7..7d6a12baa254 100644
--- a/include/linux/scmi_protocol.h
+++ b/include/linux/scmi_protocol.h
@@ -378,6 +378,18 @@ 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);
-- 
2.17.1