RE: [PATCH] firmware: arm_scmi: Add support for multiple vendors custom protocols

From: Peng Fan (OSS)
Date: Thu Feb 22 2024 - 03:32:26 EST

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Hi Cristian,

> Subject: [PATCH] firmware: arm_scmi: Add support for multiple vendors
> custom protocols

Do you have an example how to test this? Could this be used for pinctrl imx?

Thanks,
Peng.

>
> Add a mechanism to be able to tag vendor protocol modules at compile-time
> with a vendor/sub_vendor string and an implementation version and then to
> choose to load, at run-time, only those vendor protocol modules matching as
> close as possible the vendor/subvendor identification advertised by the SCMI
> platform server.
>
> In this way, any in-tree existent vendor protocol module can be build and
> shipped by default in a single kernel image, even when using the same
> clashing protocol identification numbers, since the SCMI core will take care at
> run-time to load only the ones pertinent to the running system.
>
> Signed-off-by: Cristian Marussi <cristian.marussi@xxxxxxx>
> ---
> Hi all,
>
> this is meant to address the possibility of having multiple vendors
> implementing distinct SCMI vendor protocols with possibly the same
> overlapping protocol number without the need of crafting the Kconfig at
> compile time to include only wanted protos (and without the need for a
> lottery :P)
>
> Basic idea is simple:
>
> - vendor protos HAS to be 'tagged' at build time with a vendor_id
> - vendor protos COULD also optionally be tagged at build time with
> sub_vendor_id and implemetation version
>
> - at init all the build vendor protos are registerd with the SCMI core
> using a key derived from the above tags
>
> - at SCMI probe time the platform is identified via Base protocol as
> usual and all the required vendor protos (i.e. IDs defined in the DT
> as usual) are loaded after a lookup process based on the following rules:
>
> + protocol DB is searched using the platform/Base runtime provided tags
>
> <vendor> / <sub_vendor> / <impl_ver>
>
> using the the following search logic (keys), first match:
>
> 1. proto_id / <vendor_id> / <sub_vendor_id> / <impl_ver>
>
> 2. proto_id / <vendor_id> / <sub_vendor_id> / 0
>
> 3. proto_id / <vendor_id> / NULL / 0
>
> IOW, closest match, depending on how much fine grained is your
> protocol tuned (tagged) for the platform.
>
> I am doubtful about the usage of <impl_ver>, and tempted to drop it
> since we have anyway protocol version and
> NEGOTIATE_PROTOCOL_VERSION
> to deal with slight difference in fw revision...
>
> Based on sudeep/for-linux-next on top of
>
> 1c2c88cfcb2b ("clk: scmi: Support get/set duty_cycle operations")
>
> Minimally tested ....
>
> Any feedback welcome
>
> Thanks,
> Cristian
> ---
> drivers/firmware/arm_scmi/driver.c | 166 ++++++++++++++++++++++----
> drivers/firmware/arm_scmi/protocols.h | 5 +
> 2 files changed, 149 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/firmware/arm_scmi/driver.c
> b/drivers/firmware/arm_scmi/driver.c
> index 34d77802c990..8fb2903698c9 100644
> --- a/drivers/firmware/arm_scmi/driver.c
> +++ b/drivers/firmware/arm_scmi/driver.c
> @@ -33,6 +33,7 @@
> #include <linux/processor.h>
> #include <linux/refcount.h>
> #include <linux/slab.h>
> +#include <linux/xarray.h>
>
> #include "common.h"
> #include "notify.h"
> @@ -44,8 +45,7 @@
>
> static DEFINE_IDA(scmi_id);
>
> -static DEFINE_IDR(scmi_protocols);
> -static DEFINE_SPINLOCK(protocol_lock);
> +static DEFINE_XARRAY(scmi_protocols);
>
> /* List of all SCMI devices active in system */ static LIST_HEAD(scmi_list);
> @@ -194,11 +194,90 @@ struct scmi_info {
> #define bus_nb_to_scmi_info(nb) container_of(nb, struct scmi_info,
> bus_nb)
> #define req_nb_to_scmi_info(nb) container_of(nb, struct scmi_info,
> dev_req_nb)
>
> -static const struct scmi_protocol *scmi_protocol_get(int protocol_id)
> +static unsigned long
> +scmi_vendor_protocol_signature(unsigned protocol_id, char *vendor_id,
> + char *sub_vendor_id, u32 impl_ver)
> {
> - const struct scmi_protocol *proto;
> + char *signature, *p;
> + unsigned long hash = 0;
>
> - proto = idr_find(&scmi_protocols, protocol_id);
> + /* vendor_id/sub_vendor_id guaranteed <=
> SCMI_SHORT_NAME_MAX_SIZE */
> + signature = kasprintf(GFP_KERNEL, "%02X|%s|%s|0x%08X",
> protocol_id,
> + vendor_id ?: "", sub_vendor_id ?: "", impl_ver);
> + if (!signature)
> + return 0;
> +
> + p = signature;
> + while (*p)
> + hash = partial_name_hash(tolower(*p++), hash);
> + hash = end_name_hash(hash);
> +
> + kfree(signature);
> +
> + return hash;
> +}
> +
> +static unsigned long
> +scmi_protocol_key_calculate(int protocol_id, char *vendor_id,
> + char *sub_vendor_id, u32 impl_ver) {
> + if (protocol_id < SCMI_PROTOCOL_VENDOR)
> + return protocol_id;
> + else
> + return scmi_vendor_protocol_signature(protocol_id,
> vendor_id,
> + sub_vendor_id,
> impl_ver);
> +}
> +
> +static const struct scmi_protocol *
> +scmi_vendor_protocol_lookup(int protocol_id, char *vendor_id,
> + char *sub_vendor_id, u32 impl_ver) {
> + unsigned long key;
> + struct scmi_protocol *proto = NULL;
> +
> + /* Searching for closest match ...*/
> + key = scmi_protocol_key_calculate(protocol_id, vendor_id,
> + sub_vendor_id, impl_ver);
> + if (key)
> + proto = xa_load(&scmi_protocols, key);
> +
> + if (proto)
> + return proto;
> +
> + /* Any match on vendor/sub_vendor ? */
> + if (impl_ver) {
> + key = scmi_protocol_key_calculate(protocol_id, vendor_id,
> + sub_vendor_id, 0);
> + if (key)
> + proto = xa_load(&scmi_protocols, key);
> +
> + if (proto)
> + return proto;
> + }
> +
> + /* Any match on just the vendor ? */
> + if (sub_vendor_id) {
> + key = scmi_protocol_key_calculate(protocol_id, vendor_id,
> + NULL, 0);
> + if (key)
> + proto = xa_load(&scmi_protocols, key);
> + }
> +
> + return proto;
> +}
> +
> +static const struct scmi_protocol *
> +scmi_protocol_get(int protocol_id, struct scmi_revision_info *version)
> +{
> + const struct scmi_protocol *proto = NULL;
> +
> + if (protocol_id < SCMI_PROTOCOL_VENDOR)
> + proto = xa_load(&scmi_protocols, protocol_id);
> + else
> + proto = scmi_vendor_protocol_lookup(protocol_id,
> + version->vendor_id,
> + version->sub_vendor_id,
> + version->impl_ver);
> if (!proto || !try_module_get(proto->owner)) {
> pr_warn("SCMI Protocol 0x%x not found!\n", protocol_id);
> return NULL;
> @@ -206,21 +285,47 @@ static const struct scmi_protocol
> *scmi_protocol_get(int protocol_id)
>
> pr_debug("Found SCMI Protocol 0x%x\n", protocol_id);
>
> + if (protocol_id >= SCMI_PROTOCOL_VENDOR)
> + pr_info("Loaded SCMI Vendor Protocol 0x%x - %s %s %X\n",
> + protocol_id, proto->vendor_id ?: "",
> + proto->sub_vendor_id ?: "", proto->impl_ver);
> +
> return proto;
> }
>
> -static void scmi_protocol_put(int protocol_id)
> +static void scmi_protocol_put(const struct scmi_protocol *proto)
> {
> - const struct scmi_protocol *proto;
> -
> - proto = idr_find(&scmi_protocols, protocol_id);
> if (proto)
> module_put(proto->owner);
> }
>
> +static int scmi_vendor_protocol_check(const struct scmi_protocol
> +*proto) {
> + if (!proto->vendor_id) {
> + pr_err("missing vendor_id for protocol 0x%x\n", proto->id);
> + return -EINVAL;
> + }
> +
> + if (proto->vendor_id &&
> + strlen(proto->vendor_id) >= SCMI_SHORT_NAME_MAX_SIZE) {
> + pr_err("malformed vendor_id for protocol 0x%x\n", proto-
> >id);
> + return -EINVAL;
> + }
> +
> + if (proto->sub_vendor_id &&
> + strlen(proto->sub_vendor_id) >= SCMI_SHORT_NAME_MAX_SIZE) {
> + pr_err("malformed sub_vendor_id for protocol 0x%x\n",
> + proto->id);
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> int scmi_protocol_register(const struct scmi_protocol *proto) {
> int ret;
> + unsigned long key;
>
> if (!proto) {
> pr_err("invalid protocol\n");
> @@ -232,12 +337,23 @@ int scmi_protocol_register(const struct
> scmi_protocol *proto)
> return -EINVAL;
> }
>
> - spin_lock(&protocol_lock);
> - ret = idr_alloc(&scmi_protocols, (void *)proto,
> - proto->id, proto->id + 1, GFP_ATOMIC);
> - spin_unlock(&protocol_lock);
> - if (ret != proto->id) {
> - pr_err("unable to allocate SCMI idr slot for 0x%x - err %d\n",
> + if (proto->id >= SCMI_PROTOCOL_VENDOR &&
> + scmi_vendor_protocol_check(proto))
> + return -EINVAL;
> +
> + /*
> + * Calculate a protocol key to register this protocol with the core;
> + * key value 0 is considered invalid.
> + */
> + key = scmi_protocol_key_calculate(proto->id, proto->vendor_id,
> + proto->sub_vendor_id,
> + proto->impl_ver);
> + if (!key)
> + return -EINVAL;
> +
> + ret = xa_insert(&scmi_protocols, key, (void *)proto, GFP_KERNEL);
> + if (ret) {
> + pr_err("unable to allocate SCMI protocol slot for 0x%x -
> err %d\n",
> proto->id, ret);
> return ret;
> }
> @@ -250,9 +366,15 @@ EXPORT_SYMBOL_GPL(scmi_protocol_register);
>
> void scmi_protocol_unregister(const struct scmi_protocol *proto) {
> - spin_lock(&protocol_lock);
> - idr_remove(&scmi_protocols, proto->id);
> - spin_unlock(&protocol_lock);
> + unsigned long key;
> +
> + key = scmi_protocol_key_calculate(proto->id, proto->vendor_id,
> + proto->sub_vendor_id,
> + proto->impl_ver);
> + if (!key)
> + return;
> +
> + xa_erase(&scmi_protocols, key);
>
> pr_debug("Unregistered SCMI Protocol 0x%x\n", proto->id); } @@ -
> 1888,7 +2010,7 @@ scmi_alloc_init_protocol_instance(struct scmi_info *info,
> /* Protocol specific devres group */
> gid = devres_open_group(handle->dev, NULL, GFP_KERNEL);
> if (!gid) {
> - scmi_protocol_put(proto->id);
> + scmi_protocol_put(pi->proto);
> goto out;
> }
>
> @@ -1952,7 +2074,7 @@ scmi_alloc_init_protocol_instance(struct scmi_info
> *info,
>
> clean:
> /* Take care to put the protocol module's owner before releasing all
> */
> - scmi_protocol_put(proto->id);
> + scmi_protocol_put(proto);
> devres_release_group(handle->dev, gid);
> out:
> return ERR_PTR(ret);
> @@ -1986,7 +2108,7 @@ scmi_get_protocol_instance(const struct
> scmi_handle *handle, u8 protocol_id)
> const struct scmi_protocol *proto;
>
> /* Fails if protocol not registered on bus */
> - proto = scmi_protocol_get(protocol_id);
> + proto = scmi_protocol_get(protocol_id, &info->version);
> if (proto)
> pi = scmi_alloc_init_protocol_instance(info, proto);
> else
> @@ -2041,7 +2163,7 @@ void scmi_protocol_release(const struct
> scmi_handle *handle, u8 protocol_id)
>
> idr_remove(&info->protocols, protocol_id);
>
> - scmi_protocol_put(protocol_id);
> + scmi_protocol_put(pi->proto);
>
> devres_release_group(handle->dev, gid);
> dev_dbg(handle->dev, "De-Initialized protocol: 0x%X\n", diff
> --git a/drivers/firmware/arm_scmi/protocols.h
> b/drivers/firmware/arm_scmi/protocols.h
> index 693019fff0f6..cb8dbc93584b 100644
> --- a/drivers/firmware/arm_scmi/protocols.h
> +++ b/drivers/firmware/arm_scmi/protocols.h
> @@ -29,6 +29,8 @@
> #define PROTOCOL_REV_MAJOR(x)
> ((u16)(FIELD_GET(PROTOCOL_REV_MAJOR_MASK, (x))))
> #define PROTOCOL_REV_MINOR(x)
> ((u16)(FIELD_GET(PROTOCOL_REV_MINOR_MASK, (x))))
>
> +#define SCMI_PROTOCOL_VENDOR 0x80
> +
> enum scmi_common_cmd {
> PROTOCOL_VERSION = 0x0,
> PROTOCOL_ATTRIBUTES = 0x1,
> @@ -330,6 +332,9 @@ struct scmi_protocol {
> const void *ops;
> const struct scmi_protocol_events *events;
> unsigned int supported_version;
> + u32 impl_ver;
> + char *vendor_id;
> + char *sub_vendor_id;
> };
>
> #define DEFINE_SCMI_PROTOCOL_REGISTER_UNREGISTER(name, proto) \
> --
> 2.43.0

Next message: Tejun Heo: "Re: [PATCH 6/7] workqueue: Allow cancel_work_sync() and disable_work() from atomic contexts on BH work items"
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In reply to: Cristian Marussi: "[PATCH] firmware: arm_scmi: Add support for multiple vendors custom protocols"
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