firmware: arm_scmi: Add optional transport_init/exit support

Some SCMI transport could need to perform some transport specific setup
before they can be used by the SCMI core transport layer: typically this
early setup consists in registering with some other kernel subsystem.

Add the optional capability for a transport to provide a couple of init
and exit functions that are assured to be called early during the SCMI
core initialization phase, well before the SCMI core probing step.

[ Peter: Adapted RFC patch by Cristian for submission to upstream. ]

Link: https://lore.kernel.org/r/20210803131024.40280-4-cristian.marussi@arm.com
Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
[ Cristian: Fixed scmi_transports_exit point of invocation ]
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/common.h b/drivers/firmware/arm_scmi/common.h
index 7c2b9fd..9454488 100644 (file)
--- a/drivers/firmware/arm_scmi/common.h
+++ b/drivers/firmware/arm_scmi/common.h
@@ -321,6 +321,12 @@ struct scmi_device *scmi_child_dev_find(struct device *parent,
 /**
  * struct scmi_desc - Description of SoC integration
  *
+ * @transport_init: An optional function that a transport can provide to
+ *                 initialize some transport-specific setup during SCMI core
+ *                 initialization, so ahead of SCMI core probing.
+ * @transport_exit: An optional function that a transport can provide to
+ *                 de-initialize some transport-specific setup during SCMI core
+ *                 de-initialization, so after SCMI core removal.
  * @ops: Pointer to the transport specific ops structure
  * @max_rx_timeout_ms: Timeout for communication with SoC (in Milliseconds)
  * @max_msg: Maximum number of messages that can be pending
@@ -328,6 +334,8 @@ struct scmi_device *scmi_child_dev_find(struct device *parent,
  * @max_msg_size: Maximum size of data per message that can be handled.
  */
 struct scmi_desc {
+       int (*transport_init)(void);
+       void (*transport_exit)(void);
        const struct scmi_transport_ops *ops;
        int max_rx_timeout_ms;
        int max_msg;

diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index bd7f81b..374bf97 100644 (file)
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -1581,10 +1581,65 @@ static struct platform_driver scmi_driver = {
        .remove = scmi_remove,
 };
 
+/**
+ * __scmi_transports_setup  - Common helper to call transport-specific
+ * .init/.exit code if provided.
+ *
+ * @init: A flag to distinguish between init and exit.
+ *
+ * Note that, if provided, we invoke .init/.exit functions for all the
+ * transports currently compiled in.
+ *
+ * Return: 0 on Success.
+ */
+static inline int __scmi_transports_setup(bool init)
+{
+       int ret = 0;
+       const struct of_device_id *trans;
+
+       for (trans = scmi_of_match; trans->data; trans++) {
+               const struct scmi_desc *tdesc = trans->data;
+
+               if ((init && !tdesc->transport_init) ||
+                   (!init && !tdesc->transport_exit))
+                       continue;
+
+               if (init)
+                       ret = tdesc->transport_init();
+               else
+                       tdesc->transport_exit();
+
+               if (ret) {
+                       pr_err("SCMI transport %s FAILED initialization!\n",
+                              trans->compatible);
+                       break;
+               }
+       }
+
+       return ret;
+}
+
+static int __init scmi_transports_init(void)
+{
+       return __scmi_transports_setup(true);
+}
+
+static void __exit scmi_transports_exit(void)
+{
+       __scmi_transports_setup(false);
+}
+
 static int __init scmi_driver_init(void)
 {
+       int ret;
+
        scmi_bus_init();
 
+       /* Initialize any compiled-in transport which provided an init/exit */
+       ret = scmi_transports_init();
+       if (ret)
+               return ret;
+
        scmi_base_register();
 
        scmi_clock_register();
@@ -1613,6 +1668,8 @@ static void __exit scmi_driver_exit(void)
 
        scmi_bus_exit();
 
+       scmi_transports_exit();
+
        platform_driver_unregister(&scmi_driver);
 }
 module_exit(scmi_driver_exit);