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SubjectRe: [PATCH 01/11] firmware: arm_scmi: review protocol registration interface
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Hi Cristian,

Thanks for this series!

On 10/14/20 11:05 AM, Cristian Marussi wrote:
> Extend common protocol registration routines and provide some new generic
> protocols' init/deinit helpers that tracks protocols' users and automatically
> perform the proper initialization/de-initialization on demand.
>
> Convert all protocols to use new registration schema while modifying only Base
> protocol to use also the new initialization helpers.
>
> All other standard protocols' initialization is still umodified and bound to
> SCMI devices probing.
>
> Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
> ---
> drivers/firmware/arm_scmi/base.c | 10 +-
> drivers/firmware/arm_scmi/bus.c | 61 +++++++---
> drivers/firmware/arm_scmi/clock.c | 10 +-
> drivers/firmware/arm_scmi/common.h | 31 ++++-
> drivers/firmware/arm_scmi/driver.c | 168 +++++++++++++++++++++++++++-
> drivers/firmware/arm_scmi/notify.c | 3 +-
> drivers/firmware/arm_scmi/perf.c | 10 +-
> drivers/firmware/arm_scmi/power.c | 10 +-
> drivers/firmware/arm_scmi/reset.c | 10 +-
> drivers/firmware/arm_scmi/sensors.c | 10 +-
> drivers/firmware/arm_scmi/system.c | 8 +-
> include/linux/scmi_protocol.h | 6 +-
> 12 files changed, 298 insertions(+), 39 deletions(-)
>
> diff --git a/drivers/firmware/arm_scmi/base.c b/drivers/firmware/arm_scmi/base.c
> index 017e5d8bd869..f19e08ed4369 100644
> --- a/drivers/firmware/arm_scmi/base.c
> +++ b/drivers/firmware/arm_scmi/base.c
> @@ -318,7 +318,7 @@ static const struct scmi_event_ops base_event_ops = {
> .fill_custom_report = scmi_base_fill_custom_report,
> };
>
> -int scmi_base_protocol_init(struct scmi_handle *h)
> +static int scmi_base_protocol_init(struct scmi_handle *h)
> {
> int id, ret;
> u8 *prot_imp;
> @@ -365,3 +365,11 @@ int scmi_base_protocol_init(struct scmi_handle *h)
>
> return 0;
> }
> +
> +static struct scmi_protocol scmi_base = {
> + .id = SCMI_PROTOCOL_BASE,
> + .init = &scmi_base_protocol_init,
> + .ops = NULL,
> +};
> +
> +DEFINE_SCMI_PROTOCOL_REGISTER_UNREGISTER(base, scmi_base)
> diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
> index 1377ec76a45d..afa2e4818a2b 100644
> --- a/drivers/firmware/arm_scmi/bus.c
> +++ b/drivers/firmware/arm_scmi/bus.c
> @@ -16,7 +16,7 @@
> #include "common.h"
>
> static DEFINE_IDA(scmi_bus_id);
> -static DEFINE_IDR(scmi_protocols);
> +static DEFINE_IDR(scmi_available_protocols);
> static DEFINE_SPINLOCK(protocol_lock);
>
> static const struct scmi_device_id *
> @@ -51,13 +51,29 @@ static int scmi_dev_match(struct device *dev, struct device_driver *drv)
> return 0;
> }
>
> +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) {
> + pr_warn("SCMI Protocol 0x%x not found!\n", protocol_id);
> + return NULL;
> + }
> +
> + pr_debug("GOT SCMI Protocol 0x%x\n", protocol_id);
> +
> + return proto;
> +}
> +
> static int scmi_protocol_init(int protocol_id, struct scmi_handle *handle)
> {
> - scmi_prot_init_fn_t fn = idr_find(&scmi_protocols, protocol_id);
> + const struct scmi_protocol *proto;
>
> - if (unlikely(!fn))
> + proto = idr_find(&scmi_available_protocols, protocol_id);
> + if (!proto)
> return -EINVAL;


Any reason not to use the above scmi_get_protocol here ?

> - return fn(handle);
> + return proto->init(handle);
> }
>
> static int scmi_protocol_dummy_init(struct scmi_handle *handle)
> @@ -84,7 +100,7 @@ static int scmi_dev_probe(struct device *dev)
> return ret;
>
> /* Skip protocol initialisation for additional devices */
> - idr_replace(&scmi_protocols, &scmi_protocol_dummy_init,
> + idr_replace(&scmi_available_protocols, &scmi_protocol_dummy_init,
> scmi_dev->protocol_id);
>
> return scmi_drv->probe(scmi_dev);
> @@ -194,26 +210,45 @@ void scmi_set_handle(struct scmi_device *scmi_dev)
> scmi_dev->handle = scmi_handle_get(&scmi_dev->dev);
> }
>
> -int scmi_protocol_register(int protocol_id, scmi_prot_init_fn_t fn)
> +int scmi_protocol_register(struct scmi_protocol *proto)
> {
> int ret;
>
> + if (!proto) {
> + pr_err("invalid protocol\n");
> + return -EINVAL;
> + }
> +
> + if (!proto->init) {
> + pr_err("missing .init() for protocol 0x%x\n", proto->id);
> + return -EINVAL;
> + }
> +
> spin_lock(&protocol_lock);
> - ret = idr_alloc(&scmi_protocols, fn, protocol_id, protocol_id + 1,
> - GFP_ATOMIC);
> + ret = idr_alloc(&scmi_available_protocols, proto,
> + proto->id, proto->id + 1, GFP_ATOMIC);
> spin_unlock(&protocol_lock);
> - if (ret != protocol_id)
> - pr_err("unable to allocate SCMI idr slot, err %d\n", ret);
> + if (ret != proto->id) {
> + pr_err("unable to allocate SCMI idr slot for 0x%x - err %d\n",
> + proto->id, ret);
> + return ret;
> + }
> +
> + pr_debug("Registered SCMI Protocol 0x%x\n", proto->id);
>
> - return ret;
> + return 0;
> }
> EXPORT_SYMBOL_GPL(scmi_protocol_register);
>
> -void scmi_protocol_unregister(int protocol_id)
> +void scmi_protocol_unregister(const struct scmi_protocol *proto)
> {
> spin_lock(&protocol_lock);
> - idr_remove(&scmi_protocols, protocol_id);
> + idr_remove(&scmi_available_protocols, proto->id);
> spin_unlock(&protocol_lock);
> +
> + pr_debug("Unregistered SCMI Protocol 0x%x\n", proto->id);
> +
> + return;
> }
> EXPORT_SYMBOL_GPL(scmi_protocol_unregister);
>

[...]

> diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
> index 3dfd8b6a0ebf..7de994e49884 100644
> --- a/drivers/firmware/arm_scmi/driver.c
> +++ b/drivers/firmware/arm_scmi/driver.c
> @@ -23,6 +23,7 @@
> #include <linux/of_address.h>
> #include <linux/of_device.h>
> #include <linux/processor.h>
> +#include <linux/refcount.h>
> #include <linux/slab.h>
>
> #include "common.h"
> @@ -68,6 +69,21 @@ struct scmi_xfers_info {
> spinlock_t xfer_lock;
> };
>
> +/**
> + * struct scmi_protocol_instance - Describe an initialized protocol instance.
> + * @proto: A reference to the protocol descriptor.
> + * @gid: A reference for per-protocol devres management.
> + * @users: A refcount to track effective users of this protocol.
> + *
> + * Each protocol is initialized independently once for each SCMI platform in
> + * which is defined by DT and implemented by the SCMI server fw.
> + */
> +struct scmi_protocol_instance {
> + const struct scmi_protocol *proto;
> + void *gid;
> + refcount_t users;
> +};
> +
> /**
> * struct scmi_info - Structure representing a SCMI instance
> *
> @@ -80,6 +96,10 @@ struct scmi_xfers_info {
> * @rx_minfo: Universal Receive Message management info
> * @tx_idr: IDR object to map protocol id to Tx channel info pointer
> * @rx_idr: IDR object to map protocol id to Rx channel info pointer
> + * @protocols: An array of protocols' instance descriptors initialized for
> + * this SCMI instance: populated on protocol's first attempted
> + * usage.
> + * @protocols_mtx: A mutex to protect protocols instances initialization.
> * @protocols_imp: List of protocols implemented, currently maximum of
> * MAX_PROTOCOLS_IMP elements allocated by the base protocol
> * @node: List head
> @@ -94,6 +114,9 @@ struct scmi_info {
> struct scmi_xfers_info rx_minfo;
> struct idr tx_idr;
> struct idr rx_idr;
> + struct scmi_protocol_instance *protocols[SCMI_MAX_PROTO];
> + /* Ensure mutual exclusive access to protocols instance array */
> + struct mutex protocols_mtx;
> u8 *protocols_imp;
> struct list_head node;
> int users;
> @@ -519,6 +542,132 @@ int scmi_version_get(const struct scmi_handle *handle, u8 protocol,
> return ret;
> }
>
> +/**
> + * scmi_get_protocol_instance - Protocol initialization helper.
> + * @handle: A reference to the SCMI platform instance.
> + * @protocol_id: The protocol being requested.
> + *
> + * In case the required protocol has never been requested before for this
> + * 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.
> + */
> +static struct scmi_protocol_instance * __must_check
> +scmi_get_protocol_instance(struct scmi_handle *handle, u8 protocol_id)
> +{
> + int ret = -ENOMEM;
> + void *gid;
> + struct scmi_protocol_instance *pi;
> + struct scmi_info *info = handle_to_scmi_info(handle);
> +
> + mutex_lock(&info->protocols_mtx);
> + /* Ensure protocols has been updated */
> + smp_rmb();
> + pi = info->protocols[protocol_id];
> +
> + if (!pi) {
> + const struct scmi_protocol *proto;
> +
> + /* Fail if protocol not registered on bus */
> + proto = scmi_get_protocol(protocol_id);
> + if (!proto) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + /* Protocol specific devres group */
> + gid = devres_open_group(handle->dev, NULL, GFP_KERNEL);
> + if (!gid)
> + goto out;
> +
> + pi = devm_kzalloc(handle->dev, sizeof(*pi), GFP_KERNEL);
> + if (!pi)
> + goto clean;
> +
> + pi->gid = gid;
> + pi->proto = proto;
> + refcount_set(&pi->users, 1);
> + /* proto->init is assured NON NULL by scmi_protocol_register */
> + ret = pi->proto->init(handle);

Isnt this already done in scmi_protocol_init? Or rather the init should
remain here and there is no need for it to be called from
scmi_protocol_init?



--
Warm Regards
Thara

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