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

Jonathan Cameron
2021-06-14T13:31:48Z

On Fri, 11 Jun 2021 17:59:24 +0100
Cristian Marussi <cristian.marussi@arm.com> wrote:

> 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>

Drive by comment inline. Feel free to ignore ;)

Jonathan

> ---
> 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);

Clever formatting can makes grepping for messages harder.

Perhaps
if (init)
pr_debug("SCMI Initializing %s transport\n",
trans->compatible);
else
pr_debug("SCMI Deinitializing %s transport\n",
trans->compatible);

would be nicer even though it burns some lines. Also avoids somewhat
ugly capitalization : De-Initializing xxx transport.

You could combine it with the convenient if(init) below

> +
> + 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);