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firmware: arm_scmi: Add support for multiple vendors custom protocols
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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 <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Sudeep Holla <[email protected]>
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@freefall75 @sudeep-holla
freefall75 authored and sudeep-holla committed Apr 18, 2024
1 parent 4625810 commit fc11010
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Showing 2 changed files with 162 additions and 22 deletions.
169 changes: 147 additions & 22 deletions drivers/firmware/arm_scmi/driver.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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"
Expand All @@ -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);
Expand Down Expand Up @@ -194,33 +194,141 @@ 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 int 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_BASE)
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;

key = scmi_protocol_key_calculate(protocol_id, vendor_id,
sub_vendor_id, impl_ver);
if (key)
proto = xa_load(&scmi_protocols, key);

return proto;
}

static const struct scmi_protocol *
scmi_vendor_protocol_lookup(int protocol_id, char *vendor_id,
char *sub_vendor_id, u32 impl_ver)
{
const struct scmi_protocol *proto = NULL;

/* Searching for closest match ...*/
proto = __scmi_vendor_protocol_lookup(protocol_id, vendor_id,
sub_vendor_id, impl_ver);
if (proto)
return proto;

/* Any match just on vendor/sub_vendor ? */
if (impl_ver) {
proto = __scmi_vendor_protocol_lookup(protocol_id, vendor_id,
sub_vendor_id, 0);
if (proto)
return proto;
}

/* Any match just on the vendor ? */
if (sub_vendor_id)
proto = __scmi_vendor_protocol_lookup(protocol_id, vendor_id,
NULL, 0);
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_BASE)
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;
}

pr_debug("Found SCMI Protocol 0x%x\n", protocol_id);

if (protocol_id >= SCMI_PROTOCOL_VENDOR_BASE)
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 (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");
Expand All @@ -232,12 +340,23 @@ 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_BASE &&
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;
}
Expand All @@ -250,9 +369,15 @@ 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);
}
Expand Down Expand Up @@ -1940,7 +2065,7 @@ 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(proto);
goto out;
}

Expand Down Expand Up @@ -2004,7 +2129,7 @@ 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);
Expand Down Expand Up @@ -2038,7 +2163,7 @@ 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
Expand Down Expand Up @@ -2093,7 +2218,7 @@ 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",
Expand Down
15 changes: 15 additions & 0 deletions drivers/firmware/arm_scmi/protocols.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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_BASE 0x80

enum scmi_common_cmd {
PROTOCOL_VERSION = 0x0,
PROTOCOL_ATTRIBUTES = 0x1,
Expand Down Expand Up @@ -323,6 +325,16 @@ typedef int (*scmi_prot_init_ph_fn_t)(const struct scmi_protocol_handle *);
* protocol by the agent. Each protocol implementation
* in the agent is supposed to downgrade to match the
* protocol version supported by the platform.
* @vendor_id: A firmware vendor string for vendor protocols matching.
* Ignored when @id identifies a standard protocol, cannot be NULL
* otherwise.
* @sub_vendor_id: A firmware sub_vendor string for vendor protocols matching.
* Ignored if NULL or when @id identifies a standard protocol.
* @impl_ver: A firmware implementation version for vendor protocols matching.
* Ignored if zero or if @id identifies a standard protocol.
*
* Note that vendor protocols matching at load time is performed by attempting
* the closest match first against the tuple (vendor, sub_vendor, impl_ver)
*/
struct scmi_protocol {
const u8 id;
Expand All @@ -332,6 +344,9 @@ struct scmi_protocol {
const void *ops;
const struct scmi_protocol_events *events;
unsigned int supported_version;
char *vendor_id;
char *sub_vendor_id;
u32 impl_ver;
};

#define DEFINE_SCMI_PROTOCOL_REGISTER_UNREGISTER(name, proto) \
Expand Down

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