[PATCH v5 3/3] firmware: arm_scmi: Always create devices for standard protocols
From: Hans de Goede <hidden>
Date: 2026-09-02 18:08:58
Also in:
arm-scmi, imx, linux-arm-msm, lkml
Subsystem:
system control & power/management interface (scpi/scmi) message protocol drivers, the rest · Maintainers:
Sudeep Holla, Linus Torvalds
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 <redacted>
---
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 | 48 +++++++++++++++++++++++++++++++--
1 file changed, 46 insertions(+), 2 deletions(-)
diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
index 6f667e4ffeed..10d15da76f19 100644
--- a/drivers/firmware/arm_scmi/bus.c
+++ b/drivers/firmware/arm_scmi/bus.c@@ -505,6 +505,34 @@ _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 *
@@ -534,11 +562,25 @@ 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. */
@@ -549,7 +591,9 @@ struct scmi_device *scmi_device_create(struct device_node *np, /* 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