* [PATCH v6 1/4] module: add SCMI device table alias support
2026-09-11 15:23 [PATCH v6 0/4] firmware: arm_scmi: fix module auto-loading Hans de Goede
@ 2026-09-11 15:23 ` Hans de Goede
2026-09-11 15:23 ` [PATCH v6 2/4] firmware: arm_scmi: Fix scmi_protocol_table_register() error handling Hans de Goede
` (2 subsequent siblings)
3 siblings, 0 replies; 7+ messages in thread
From: Hans de Goede @ 2026-09-11 15:23 UTC (permalink / raw)
To: Bjorn Andersson, Cristian Marussi, Sudeep Holla
Cc: Hans de Goede, Daniel Lezcano, Bjorn Andersson, Frank.Li,
arm-scmi, linux-arm-kernel, linux-arm-msm, imx, linux-kernel
From: Bjorn Andersson <bjorn.andersson@oss.qualcomm.com>
SCMI client drivers already describe their bus match data with
MODULE_DEVICE_TABLE(scmi, ...), but modpost does not know how to consume
SCMI device tables. As a result, SCMI modules do not get generated module
aliases from their id tables.
Move struct scmi_device_id to mod_devicetable.h so it has a fixed layout
visible to modpost, add the corresponding generated offsets and teach
file2alias to emit scmi:<protocol>:<name> aliases.
Use the same stable alias format for SCMI device uevents and sysfs
modaliases. The previous string included the instance-specific device
name, which is not useful for matching modules.
Assisted-by: Codex:GPT-5.5
Reviewed-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Tested-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@oss.qualcomm.com>
Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
---
Changes in v4:
- Drop unused driver_data member from struct scmi_device_id (Uwe)
- Drop device-id/scmi.h include from mod_devicetable.h (Uwe)
- Add device-id/scmi.h to devicetable-offsets.c and file2alias.c (Uwe)
Changes in v3:
- Adjust for ad428f5811bd ("mod_devicetable.h: Split into per subsystem
headers")
- Add '\n' to modalias_show() output, matching other subsystems' modalias
Changes in v2:
- Drop #include <linux/mod_devicetable.h> from scmi_protocol.h
- Link to v1: https://patch.msgid.link/20260616-scmi-modalias-v1-0-662b8dd52ab2@oss.qualcomm.com
---
MAINTAINERS | 1 +
drivers/firmware/arm_scmi/bus.c | 21 ++++++++++-----------
include/linux/device-id/scmi.h | 17 +++++++++++++++++
include/linux/scmi_protocol.h | 6 +-----
scripts/mod/devicetable-offsets.c | 5 +++++
scripts/mod/file2alias.c | 12 ++++++++++++
6 files changed, 46 insertions(+), 16 deletions(-)
create mode 100644 include/linux/device-id/scmi.h
diff --git a/MAINTAINERS b/MAINTAINERS
index fc6ca082106f..ee5beee606fc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -26334,6 +26334,7 @@ F: drivers/pmdomain/arm/
F: drivers/powercap/arm_scmi_powercap.c
F: drivers/regulator/scmi-regulator.c
F: drivers/reset/reset-scmi.c
+F: include/linux/device-id/scmi.h
F: include/linux/sc[mp]i_protocol.h
F: include/trace/events/scmi.h
F: include/uapi/linux/virtio_scmi.h
diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
index 793be9eabaed..d12d5de15a1a 100644
--- a/drivers/firmware/arm_scmi/bus.c
+++ b/drivers/firmware/arm_scmi/bus.c
@@ -13,11 +13,12 @@
#include <linux/of.h>
#include <linux/kernel.h>
#include <linux/slab.h>
+#include <linux/string.h>
#include <linux/device.h>
#include "common.h"
-#define SCMI_UEVENT_MODALIAS_FMT "%s:%02x:%s"
+#define SCMI_UEVENT_MODALIAS_FMT SCMI_MODULE_PREFIX "%02x:%s"
BLOCKING_NOTIFIER_HEAD(scmi_requested_devices_nh);
EXPORT_SYMBOL_GPL(scmi_requested_devices_nh);
@@ -141,7 +142,7 @@ static int scmi_protocol_table_register(const struct scmi_device_id *id_table)
int ret = 0;
const struct scmi_device_id *entry;
- for (entry = id_table; entry->name && ret == 0; entry++)
+ for (entry = id_table; entry->name[0] && ret == 0; entry++)
ret = scmi_protocol_device_request(entry);
return ret;
@@ -197,18 +198,18 @@ scmi_protocol_table_unregister(const struct scmi_device_id *id_table)
{
const struct scmi_device_id *entry;
- for (entry = id_table; entry->name; entry++)
+ for (entry = id_table; entry->name[0]; entry++)
scmi_protocol_device_unrequest(entry);
}
static int scmi_dev_match_by_id_table(struct scmi_device *scmi_dev,
const struct scmi_device_id *id_table)
{
- if (!id_table || !id_table->name)
+ if (!id_table || !id_table->name[0])
return 0;
/* Always skip transport devices from matching */
- for (; id_table->protocol_id && id_table->name; id_table++)
+ for (; id_table->protocol_id && id_table->name[0]; id_table++)
if (id_table->protocol_id == scmi_dev->protocol_id &&
strncmp(scmi_dev->name, "__scmi_transport_device", 23) &&
!strcmp(id_table->name, scmi_dev->name))
@@ -245,7 +246,7 @@ static struct scmi_device *scmi_child_dev_find(struct device *parent,
struct device *dev;
id_table[0].protocol_id = prot_id;
- id_table[0].name = name;
+ strscpy(id_table[0].name, name, sizeof(id_table[0].name));
dev = device_find_child(parent, &id_table, scmi_match_by_id_table);
if (!dev)
@@ -282,8 +283,7 @@ static int scmi_device_uevent(const struct device *dev, struct kobj_uevent_env *
const struct scmi_device *scmi_dev = to_scmi_dev(dev);
return add_uevent_var(env, "MODALIAS=" SCMI_UEVENT_MODALIAS_FMT,
- dev_name(&scmi_dev->dev), scmi_dev->protocol_id,
- scmi_dev->name);
+ scmi_dev->protocol_id, scmi_dev->name);
}
static ssize_t modalias_show(struct device *dev,
@@ -291,9 +291,8 @@ static ssize_t modalias_show(struct device *dev,
{
struct scmi_device *scmi_dev = to_scmi_dev(dev);
- return sysfs_emit(buf, SCMI_UEVENT_MODALIAS_FMT,
- dev_name(&scmi_dev->dev), scmi_dev->protocol_id,
- scmi_dev->name);
+ return sysfs_emit(buf, SCMI_UEVENT_MODALIAS_FMT "\n",
+ scmi_dev->protocol_id, scmi_dev->name);
}
static DEVICE_ATTR_RO(modalias);
diff --git a/include/linux/device-id/scmi.h b/include/linux/device-id/scmi.h
new file mode 100644
index 000000000000..1b4ccfa9dcc5
--- /dev/null
+++ b/include/linux/device-id/scmi.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+#ifndef LINUX_DEVICE_ID_SCMI_H
+#define LINUX_DEVICE_ID_SCMI_H
+
+#ifdef __KERNEL__
+#include <linux/types.h>
+#endif
+
+#define SCMI_NAME_SIZE 32
+#define SCMI_MODULE_PREFIX "scmi:"
+
+struct scmi_device_id {
+ __u8 protocol_id;
+ char name[SCMI_NAME_SIZE];
+};
+
+#endif /* ifndef LINUX_DEVICE_ID_SCMI_H */
diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
index 5ab73b1ab9aa..ba53302d95f5 100644
--- a/include/linux/scmi_protocol.h
+++ b/include/linux/scmi_protocol.h
@@ -9,6 +9,7 @@
#define _LINUX_SCMI_PROTOCOL_H
#include <linux/bitfield.h>
+#include <linux/device-id/scmi.h>
#include <linux/device.h>
#include <linux/notifier.h>
#include <linux/types.h>
@@ -951,11 +952,6 @@ struct scmi_device {
#define to_scmi_dev(d) container_of_const(d, struct scmi_device, dev)
-struct scmi_device_id {
- u8 protocol_id;
- const char *name;
-};
-
struct scmi_driver {
const char *name;
int (*probe)(struct scmi_device *sdev);
diff --git a/scripts/mod/devicetable-offsets.c b/scripts/mod/devicetable-offsets.c
index b4178c42d08f..91ec3704ee2b 100644
--- a/scripts/mod/devicetable-offsets.c
+++ b/scripts/mod/devicetable-offsets.c
@@ -1,5 +1,6 @@
// SPDX-License-Identifier: GPL-2.0
#define COMPILE_OFFSETS
+#include <linux/device-id/scmi.h>
#include <linux/kbuild.h>
#include <linux/mod_devicetable.h>
@@ -144,6 +145,10 @@ int main(void)
DEVID(rpmsg_device_id);
DEVID_FIELD(rpmsg_device_id, name);
+ DEVID(scmi_device_id);
+ DEVID_FIELD(scmi_device_id, protocol_id);
+ DEVID_FIELD(scmi_device_id, name);
+
DEVID(i2c_device_id);
DEVID_FIELD(i2c_device_id, name);
diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index 8d36c74dec2d..5379b1def07b 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -121,6 +121,7 @@ typedef struct {
/* Big exception to the "don't include kernel headers into userspace, which
* even potentially has different endianness and word sizes, since
* we handle those differences explicitly below */
+#include "../../include/linux/device-id/scmi.h"
#include "../../include/linux/mod_devicetable.h"
struct devtable {
@@ -852,6 +853,16 @@ static void do_rpmsg_entry(struct module *mod, void *symval)
module_alias_printf(mod, false, RPMSG_DEVICE_MODALIAS_FMT, *name);
}
+/* Looks like: scmi:NN:S */
+static void do_scmi_entry(struct module *mod, void *symval)
+{
+ DEF_FIELD(symval, scmi_device_id, protocol_id);
+ DEF_FIELD_ADDR(symval, scmi_device_id, name);
+
+ module_alias_printf(mod, false, SCMI_MODULE_PREFIX "%02x:%s",
+ protocol_id, *name);
+}
+
/* Looks like: i2c:S */
static void do_i2c_entry(struct module *mod, void *symval)
{
@@ -1491,6 +1502,7 @@ static const struct devtable devtable[] = {
{"virtio", SIZE_virtio_device_id, do_virtio_entry},
{"vmbus", SIZE_hv_vmbus_device_id, do_vmbus_entry},
{"rpmsg", SIZE_rpmsg_device_id, do_rpmsg_entry},
+ {"scmi", SIZE_scmi_device_id, do_scmi_entry},
{"i2c", SIZE_i2c_device_id, do_i2c_entry},
{"i3c", SIZE_i3c_device_id, do_i3c_entry},
{"slim", SIZE_slim_device_id, do_slim_entry},
--
2.55.0
^ permalink raw reply related [flat|nested] 7+ messages in thread* [PATCH v6 4/4] firmware: arm_scmi: Always create devices for standard protocols
2026-09-11 15:23 [PATCH v6 0/4] firmware: arm_scmi: fix module auto-loading Hans de Goede
` (2 preceding siblings ...)
2026-09-11 15:23 ` [PATCH v6 3/4] firmware: arm_scmi: Fix scmi_protocol_device_unrequest() race Hans de Goede
@ 2026-09-11 15:23 ` Hans de Goede
3 siblings, 0 replies; 7+ messages in thread
From: Hans de Goede @ 2026-09-11 15:23 UTC (permalink / raw)
To: Bjorn Andersson, Cristian Marussi, Sudeep Holla
Cc: Hans de Goede, Daniel Lezcano, Bjorn Andersson, Frank.Li,
arm-scmi, linux-arm-kernel, linux-arm-msm, imx, linux-kernel
Protocol driver module auto-loading requires the devices to already be
created for udev to get the necessary uevents based on which udev loads
modules. But SCMI devices are only created after their { protocol, name }
device-id has been added to the requested-devices list which is done from
scmi_driver_register().
This creates a circular dependency where device creation is waiting for
the driver to register and loading the module with the driver is waiting
for the device to be created.
Add a list of standard protocol device-ids and always create devices for
these without relying on these being added to the requested-devices list.
This removes the circular dependency, fixing module auto-loading.
Signed-off-by: Hans de Goede <johannes.goede@oss.qualcomm.com>
---
Changes in v6:
- Replace the if (!phead) return NULL; early exit with return scmi_dev;
Since a standard protocol device may have been created at this point.
Changes in v5:
- This is a new patch in v5 replacing "Pre-register protocol, name tupples
for standard protocol". Pre-registering requires
scmi_protocol_device_request() to allow duplicate device-ids, but then if
the first driver of two with duplicate devce-ids gets unloaded device
creation for the second driver will fail. Allowing duplicates causes all
kinds of problems, so this new approach avoids this.
---
drivers/firmware/arm_scmi/bus.c | 50 +++++++++++++++++++++++++++++++--
1 file changed, 47 insertions(+), 3 deletions(-)
diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
index 651d4ba06574..ea59dcd95b6a 100644
--- a/drivers/firmware/arm_scmi/bus.c
+++ b/drivers/firmware/arm_scmi/bus.c
@@ -511,6 +511,34 @@ _scmi_device_create(struct device_node *np, struct device *parent,
return sdev;
}
+/* Standard protocols table */
+static const struct scmi_device_id scmi_std_id_table[] = {
+ { SCMI_PROTOCOL_POWER, "genpd" },
+ { SCMI_PROTOCOL_SYSTEM, "syspower" },
+ { SCMI_PROTOCOL_PERF, "perf" },
+ { SCMI_PROTOCOL_PERF, "cpufreq" },
+ { SCMI_PROTOCOL_CLOCK, "clocks" },
+ { SCMI_PROTOCOL_SENSOR, "hwmon" },
+ { SCMI_PROTOCOL_SENSOR, "iiodev" },
+ { SCMI_PROTOCOL_RESET, "reset" },
+ { SCMI_PROTOCOL_VOLTAGE, "regulator" },
+ { SCMI_PROTOCOL_POWERCAP, "powercap" },
+ { SCMI_PROTOCOL_PINCTRL, "pinctrl" },
+ { SCMI_PROTOCOL_PINCTRL, "pinctrl-imx" },
+ { },
+};
+
+static bool scmi_device_id_in_std_id_table(const struct scmi_device_id *id)
+{
+ for (int i = 0; scmi_std_id_table[i].name[0]; i++) {
+ if (scmi_std_id_table[i].protocol_id == id->protocol_id &&
+ !strcmp(scmi_std_id_table[i].name, id->name))
+ return true;
+ }
+
+ return false;
+}
+
/**
* scmi_device_create - A method to create one or more SCMI devices
*
@@ -540,22 +568,38 @@ struct scmi_device *scmi_device_create(struct device_node *np,
{
struct list_head *phead;
struct scmi_requested_dev *rdev;
- struct scmi_device *scmi_dev = NULL;
+ struct scmi_device *sdev, *scmi_dev = NULL;
if (name)
return _scmi_device_create(np, parent, protocol, name);
+ /*
+ * Always create devices for standard protocols, even if the device-ids
+ * have not been registered into scmi_requested_devices yet. This allows
+ * auto-loading of SCMI protocol driver modules for standard protocols.
+ */
+ for (int i = 0; scmi_std_id_table[i].name[0]; i++) {
+ if (scmi_std_id_table[i].protocol_id != protocol)
+ continue;
+
+ sdev = _scmi_device_create(np, parent, protocol, scmi_std_id_table[i].name);
+ if (sdev)
+ scmi_dev = sdev;
+ }
+
mutex_lock(&scmi_requested_devices_mtx);
phead = idr_find(&scmi_requested_devices, protocol);
/* Nothing to do. */
if (!phead) {
mutex_unlock(&scmi_requested_devices_mtx);
- return NULL;
+ return scmi_dev;
}
/* Walk the list of requested devices for protocol and create them */
list_for_each_entry(rdev, phead, node) {
- struct scmi_device *sdev;
+ /* Standard proto matches already have their dev created above */
+ if (scmi_device_id_in_std_id_table(rdev->id_table))
+ continue;
sdev = _scmi_device_create(np, parent,
rdev->id_table->protocol_id,
--
2.55.0
^ permalink raw reply related [flat|nested] 7+ messages in thread