firmware: arm_scmi: Add protocol modularization support

Extend SCMI protocols accounting mechanism to address possible module
usage and add the support to possibly define new protocols as loadable
modules.

Keep the standard protocols built into the SCMI core.

Link: https://lore.kernel.org/r/20210316124903.35011-38-cristian.marussi@arm.com
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>

diff --git a/drivers/firmware/arm_scmi/base.c b/drivers/firmware/arm_scmi/base.c
index 0d28f0f825b6fb1a384b56c3fbe909f5ac7ac68d..de416f9e792132ad944a697a46ac2e87f7a84999 100644 (file)
--- 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,
        .instance_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 992d50e101112cbb4edf0557477939a71fbe0486..aadf2da215619db2efc8aa48eee4156b3d0bfee7 100644 (file)
--- a/drivers/firmware/arm_scmi/bus.c
+++ b/drivers/firmware/arm_scmi/bus.c
@@ -56,7 +56,7 @@ const struct scmi_protocol *scmi_protocol_get(int protocol_id)
        const struct scmi_protocol *proto;
 
        proto = idr_find(&scmi_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_protocol_get(int protocol_id)
        return proto;
 }
 
+void scmi_protocol_put(int protocol_id)
+{
+       const struct scmi_protocol *proto;
+
+       proto = idr_find(&scmi_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 827cf25fc122f969188e136adea7a5ca3abf80bd..35b56c8ba0c0ef7047ecb0e87678df889385758e 100644 (file)
--- a/drivers/firmware/arm_scmi/clock.c
+++ b/drivers/firmware/arm_scmi/clock.c
@@ -5,6 +5,7 @@
  * Copyright (C) 2018-2021 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,
        .instance_init = &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 c093f332cdcdc5fcf662140e2e3aec79f38be7ab..762dd5419700c133741920603421a1cfad135351 100644 (file)
--- 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.
  * @instance_init: Mandatory protocol initialization function.
  * @instance_deinit: 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            instance_init;
        const scmi_prot_init_ph_fn_t            instance_deinit;
        const void                              *ops;
@@ -257,6 +260,7 @@ void __exit scmi_##name##_unregister(void)                  \
 }
 
 const struct scmi_protocol *scmi_protocol_get(int protocol_id);
+void scmi_protocol_put(int protocol_id);
 
 int scmi_protocol_acquire(const struct scmi_handle *handle, u8 protocol_id);
 void scmi_protocol_release(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 563a641310357b547c9d0e8a2409df56b5e6c29f..c25c20c150dc961c9b2ecf9e46dd77083c999ec4 100644 (file)
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -660,7 +660,8 @@ scmi_revision_area_get(const struct scmi_protocol_handle *ph)
  *
  * Context: Assumes to be called with @protocols_mtx already acquired.
  * Return: A reference to a freshly allocated and initialized protocol instance
- *        or ERR_PTR on failure.
+ *        or ERR_PTR on failure. On failure the @proto reference is at first
+ *        put using @scmi_protocol_put() before releasing all the devres group.
  */
 static struct scmi_protocol_instance *
 scmi_alloc_init_protocol_instance(struct scmi_info *info,
@@ -673,8 +674,10 @@ scmi_alloc_init_protocol_instance(struct scmi_info *info,
 
        /* Protocol specific devres group */
        gid = devres_open_group(handle->dev, NULL, GFP_KERNEL);
-       if (!gid)
+       if (!gid) {
+               scmi_protocol_put(proto->id);
                goto out;
+       }
 
        pi = devm_kzalloc(handle->dev, sizeof(*pi), GFP_KERNEL);
        if (!pi)
@@ -718,6 +721,8 @@ scmi_alloc_init_protocol_instance(struct scmi_info *info,
        return pi;
 
 clean:
+       /* Take care to put the protocol module's owner before releasing all */
+       scmi_protocol_put(proto->id);
        devres_release_group(handle->dev, gid);
 out:
        return ERR_PTR(ret);
@@ -732,7 +737,9 @@ out:
  * instance, allocate and initialize all the needed structures while handling
  * resource allocation with a dedicated per-protocol devres subgroup.
  *
- * Return: A reference to an initialized protocol instance or error on failure.
+ * Return: A reference to an initialized protocol instance or error on failure:
+ *        in particular returns -EPROBE_DEFER when the desired protocol could
+ *        NOT be found.
  */
 static struct scmi_protocol_instance * __must_check
 scmi_get_protocol_instance(const struct scmi_handle *handle, u8 protocol_id)
@@ -753,7 +760,7 @@ scmi_get_protocol_instance(const struct scmi_handle *handle, u8 protocol_id)
                if (proto)
                        pi = scmi_alloc_init_protocol_instance(info, proto);
                else
-                       pi = ERR_PTR(-ENODEV);
+                       pi = ERR_PTR(-EPROBE_DEFER);
        }
        mutex_unlock(&info->protocols_mtx);
 
@@ -804,6 +811,8 @@ void scmi_protocol_release(const struct scmi_handle *handle, u8 protocol_id)
 
                idr_remove(&info->protocols, protocol_id);
 
+               scmi_protocol_put(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 059d6214f93b8c769d32811265bee08e0a608f01..f4cd5193b9617f8ed70bd3d5fd10d24573130c96 100644 (file)
--- 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,
        .instance_init = &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 e0987f0a8fb276ecbc9f925b9b7fd6320e4cc725..ad2ab080f3443c251153fa606f2f4fd53e369655 100644 (file)
--- 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,
        .instance_init = &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 48b487302db8372fb373bda5dfcfc87a86b70900..9bf2478ec6d1765d81e8afafc8b9ec4df0b74ebc 100644 (file)
--- 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,
        .instance_init = &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 935c4b08829dab914bdb841c3d3e0d5aa60f05ba..2c88aa22155972e1085b60faa4223dec3f1012dd 100644 (file)
--- 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,
        .instance_init = &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 3631a9f94d277761c4ac3a319a41a923ca07326b..e5175ef73b40e0d0375466f647203dd91299f3eb 100644 (file)
--- 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,
        .instance_init = &scmi_system_protocol_init,
        .ops = NULL,
        .events = &system_protocol_events,

diff --git a/drivers/firmware/arm_scmi/voltage.c b/drivers/firmware/arm_scmi/voltage.c
index 364bc14aa5fe7d62fd27f589ee979f1b09a1d8aa..a5048956a0be9441be1cb9035b50933b929d658e 100644 (file)
--- a/drivers/firmware/arm_scmi/voltage.c
+++ b/drivers/firmware/arm_scmi/voltage.c
@@ -5,6 +5,7 @@
  * Copyright (C) 2020-2021 ARM Ltd.
  */
 
+#include <linux/module.h>
 #include <linux/scmi_protocol.h>
 
 #include "common.h"
@@ -371,6 +372,7 @@ static int scmi_voltage_protocol_init(const struct scmi_protocol_handle *ph)
 
 static const struct scmi_protocol scmi_voltage = {
        .id = SCMI_PROTOCOL_VOLTAGE,
+       .owner = THIS_MODULE,
        .instance_init = &scmi_voltage_protocol_init,
        .ops = &voltage_proto_ops,
 };

diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
index b80496d519f30a0aeb4edf91893edf6891b6151d..79d0a1237e6cabef0decff4b43cd7536ad5d9536 100644 (file)
--- a/include/linux/scmi_protocol.h
+++ b/include/linux/scmi_protocol.h
@@ -704,6 +704,18 @@ 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);