[PATCH 0/2] Add SCMI Vendor module autoload support

[PATCH 0/2] Add SCMI Vendor module autoload support

[Cristian Marussi]

Hi,

a tiny series to add the capability to automatically load the proper
vendor protocol module when an SCMI driver tries to use it; while proper
vendor protocol selection is already provided by the SCMI core, automatic
loading of vendor protocols was not.

Lookup is now based on module aliases following the pattern:

	scmi-protocol-0x<PROTO_ID_NN>-<VENDOR_ID>

In [2/2] proper aliases are added to existing i.MX Vendor protocols...
...could not find a better way to build the alias string automagically...

...any advice is welcome in these regards...and any feedback too !

Thanks,
Cristian

Cristian Marussi (2):
  firmware: arm_scmi: Support vendor protocol modules autoloading
  firmware: arm_scmi: Add module aliases to i.MX vendor protocols

 drivers/firmware/arm_scmi/driver.c            | 56 +++++++++++++++----
 .../arm_scmi/vendors/imx/imx-sm-bbm.c         |  5 +-
 .../arm_scmi/vendors/imx/imx-sm-misc.c        |  5 +-
 include/linux/scmi_imx_protocol.h             |  9 +--
 4 files changed, 57 insertions(+), 18 deletions(-)

-- 
2.47.0

[PATCH 1/2] firmware: arm_scmi: Support vendor protocol modules autoloading

[Cristian Marussi]

SCMI vendor protocols namespace is shared amongst all vendors so that there
can be multiple implementation for the same protocol ID by different
vendors, exposing completely different functionalities and used by distinct
SCMI vendor drivers.

For these reasons, at runtime, when some driver asks for a protocol, the
proper implementation to use is chosen based on the SCMI vendor/subvendor/
impl_version data as advertised by the platform SCMI server and gathered
from the SCMI core during stack initialization: this enables proper runtime
selection of vendor protocols even when many different protocols from
different vendors are built into the same image via a common defconfig.

This same selection mechanism works similarly well even when all the vendor
protocols are compiled as loadable modules, as long as all such required
protocol modules have been previously loaded by some other means.

Add support for the automatic loading of vendor protocol modules, based on
protocol/vendor IDs, when an SCMI driver attempts to use such a protocol.

Reported-by: Johan Hovold <johan+linaro@kernel.org>
Closes: https://lore.kernel.org/lkml/ZytnRc94iKUfMYH0@hovoldconsulting.com/
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
---
 drivers/firmware/arm_scmi/driver.c | 56 ++++++++++++++++++++++++------
 1 file changed, 46 insertions(+), 10 deletions(-)

diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index eeed1689b208..60050da54bf2 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -24,6 +24,7 @@
 #include <linux/io.h>
 #include <linux/io-64-nonatomic-hi-lo.h>
 #include <linux/kernel.h>
+#include <linux/kmod.h>
 #include <linux/ktime.h>
 #include <linux/hashtable.h>
 #include <linux/list.h>
@@ -43,6 +44,8 @@
 #define CREATE_TRACE_POINTS
 #include <trace/events/scmi.h>
 
+#define SCMI_VENDOR_MODULE_ALIAS_FMT	"scmi-protocol-0x%02x-%s"
+
 static DEFINE_IDA(scmi_id);
 
 static DEFINE_XARRAY(scmi_protocols);
@@ -275,6 +278,44 @@ scmi_vendor_protocol_lookup(int protocol_id, char *vendor_id,
 	return proto;
 }
 
+static const struct scmi_protocol *
+scmi_vendor_protocol_get(int protocol_id, struct scmi_revision_info *version)
+{
+	const struct scmi_protocol *proto;
+
+	proto = scmi_vendor_protocol_lookup(protocol_id, version->vendor_id,
+					    version->sub_vendor_id,
+					    version->impl_ver);
+	if (!proto) {
+		int ret;
+
+		pr_debug("Looking for '" SCMI_VENDOR_MODULE_ALIAS_FMT "'\n",
+			 protocol_id, version->vendor_id);
+
+		/* Note that vendor_id is mandatory for vendor protocols */
+		ret = request_module(SCMI_VENDOR_MODULE_ALIAS_FMT,
+				     protocol_id, version->vendor_id);
+		if (ret) {
+			pr_warn("Problem loading module for protocol 0x%x\n",
+				protocol_id);
+			return NULL;
+		}
+
+		/* Lookup again, once modules loaded */
+		proto = scmi_vendor_protocol_lookup(protocol_id,
+						    version->vendor_id,
+						    version->sub_vendor_id,
+						    version->impl_ver);
+	}
+
+	if (proto)
+		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 const struct scmi_protocol *
 scmi_protocol_get(int protocol_id, struct scmi_revision_info *version)
 {
@@ -283,10 +324,8 @@ scmi_protocol_get(int protocol_id, struct scmi_revision_info *version)
 	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);
+		proto = scmi_vendor_protocol_get(protocol_id, version);
+
 	if (!proto || !try_module_get(proto->owner)) {
 		pr_warn("SCMI Protocol 0x%x not found!\n", protocol_id);
 		return NULL;
@@ -294,11 +333,6 @@ scmi_protocol_get(int protocol_id, struct scmi_revision_info *version)
 
 	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;
 }
 
@@ -366,7 +400,9 @@ int scmi_protocol_register(const struct scmi_protocol *proto)
 		return ret;
 	}
 
-	pr_debug("Registered SCMI Protocol 0x%x\n", proto->id);
+	pr_debug("Registered SCMI Protocol 0x%x - %s  %s  0x%08X\n",
+		 proto->id, proto->vendor_id, proto->sub_vendor_id,
+		 proto->impl_ver);
 
 	return 0;
 }
-- 
2.47.0

[PATCH 2/2] firmware: arm_scmi: Add module aliases to i.MX vendor protocols

[Cristian Marussi]

Using the pattern 'scmi-protocol-0x<PROTO_ID>-<VEND_ID>' as MODULE_ALIAS
allows the SCMI core to autoload this protocol, if built as a module, when
its protocol operations are requested by an SCMI driver.

Cc: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
---
 drivers/firmware/arm_scmi/vendors/imx/imx-sm-bbm.c  | 5 +++--
 drivers/firmware/arm_scmi/vendors/imx/imx-sm-misc.c | 5 +++--
 include/linux/scmi_imx_protocol.h                   | 9 +++++----
 3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/drivers/firmware/arm_scmi/vendors/imx/imx-sm-bbm.c b/drivers/firmware/arm_scmi/vendors/imx/imx-sm-bbm.c
index 17799eacf06c..aa176c1a5eef 100644
--- a/drivers/firmware/arm_scmi/vendors/imx/imx-sm-bbm.c
+++ b/drivers/firmware/arm_scmi/vendors/imx/imx-sm-bbm.c
@@ -374,10 +374,11 @@ static const struct scmi_protocol scmi_imx_bbm = {
 	.ops = &scmi_imx_bbm_proto_ops,
 	.events = &scmi_imx_bbm_protocol_events,
 	.supported_version = SCMI_PROTOCOL_SUPPORTED_VERSION,
-	.vendor_id = "NXP",
-	.sub_vendor_id = "IMX",
+	.vendor_id = SCMI_IMX_VENDOR,
+	.sub_vendor_id = SCMI_IMX_SUBVENDOR,
 };
 module_scmi_protocol(scmi_imx_bbm);
 
+MODULE_ALIAS("scmi-protocol-" __stringify(SCMI_PROTOCOL_IMX_BBM) "-" SCMI_IMX_VENDOR);
 MODULE_DESCRIPTION("i.MX SCMI BBM driver");
 MODULE_LICENSE("GPL");
diff --git a/drivers/firmware/arm_scmi/vendors/imx/imx-sm-misc.c b/drivers/firmware/arm_scmi/vendors/imx/imx-sm-misc.c
index a86ab9b35953..83b69fc4fba5 100644
--- a/drivers/firmware/arm_scmi/vendors/imx/imx-sm-misc.c
+++ b/drivers/firmware/arm_scmi/vendors/imx/imx-sm-misc.c
@@ -309,10 +309,11 @@ static const struct scmi_protocol scmi_imx_misc = {
 	.ops = &scmi_imx_misc_proto_ops,
 	.events = &scmi_imx_misc_protocol_events,
 	.supported_version = SCMI_PROTOCOL_SUPPORTED_VERSION,
-	.vendor_id = "NXP",
-	.sub_vendor_id = "IMX",
+	.vendor_id = SCMI_IMX_VENDOR,
+	.sub_vendor_id = SCMI_IMX_SUBVENDOR,
 };
 module_scmi_protocol(scmi_imx_misc);
 
+MODULE_ALIAS("scmi-protocol-" __stringify(SCMI_PROTOCOL_IMX_MISC) "-" SCMI_IMX_VENDOR);
 MODULE_DESCRIPTION("i.MX SCMI MISC driver");
 MODULE_LICENSE("GPL");
diff --git a/include/linux/scmi_imx_protocol.h b/include/linux/scmi_imx_protocol.h
index 066216f1357a..53b356a26414 100644
--- a/include/linux/scmi_imx_protocol.h
+++ b/include/linux/scmi_imx_protocol.h
@@ -13,10 +13,11 @@
 #include <linux/notifier.h>
 #include <linux/types.h>
 
-enum scmi_nxp_protocol {
-	SCMI_PROTOCOL_IMX_BBM = 0x81,
-	SCMI_PROTOCOL_IMX_MISC = 0x84,
-};
+#define	SCMI_PROTOCOL_IMX_BBM	0x81
+#define	SCMI_PROTOCOL_IMX_MISC	0x84
+
+#define SCMI_IMX_VENDOR		"NXP"
+#define SCMI_IMX_SUBVENDOR	"IMX"
 
 struct scmi_imx_bbm_proto_ops {
 	int (*rtc_time_set)(const struct scmi_protocol_handle *ph, u32 id,
-- 
2.47.0

Re: [PATCH 2/2] firmware: arm_scmi: Add module aliases to i.MX vendor protocols

[Peng Fan]

On Tue, Dec 03, 2024 at 08:00:38PM +0000, Cristian Marussi wrote:
>Using the pattern 'scmi-protocol-0x<PROTO_ID>-<VEND_ID>' as MODULE_ALIAS
>allows the SCMI core to autoload this protocol, if built as a module, when
>its protocol operations are requested by an SCMI driver.
>
>Cc: Peng Fan <peng.fan@nxp.com>
>Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
>---

Acked-by: Peng Fan <peng.fan@nxp.com>