[PATCH v4 03/16] firmware: arm_scmi: Add transport optional init/exit support

Cristian Marussi
2021-06-11T17:00:37Z

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. ]
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>
---
drivers/firmware/arm_scmi/common.h | 8 ++++
drivers/firmware/arm_scmi/driver.c | 59 ++++++++++++++++++++++++++++++
2 files changed, 67 insertions(+)

diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
index 7c2b9fd7e929..6bb734e0e3ac 100644
--- 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
*
+ * @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.
+ * @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 (*init)(void);
+ void (*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 f15d75af87ea..20f8f0581f3a 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -1594,10 +1594,67 @@ 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->init) || (!init && !tdesc->exit))
+ continue;
+
+ pr_debug("SCMI %sInitializing %s transport\n",
+ init ? "" : "De-", trans->compatible);
+
+ if (init)
+ ret = tdesc->init();
+ else
+ tdesc->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();
@@ -1626,6 +1683,8 @@ static void __exit scmi_driver_exit(void)

scmi_bus_exit();

+ scmi_transports_exit();
+
platform_driver_unregister(&scmi_driver);
}
module_exit(scmi_driver_exit);
--
2.17.1