[PATCH 7/9] firmware: arm_scmi: Refactor device create/destroy helpers
Cristian Marussi
cristian.marussi at arm.com
Thu Dec 22 10:50:47 PST 2022
Refactor SCMI device create/destroy helpers: it is now possible to ask
for the creation of all the currently requested devices for a whole
protocol, not only for the creation of a single well-defined device.
While at that, re-instate uniqueness checks on the creation of SCMI
SystemPower devices.
Signed-off-by: Cristian Marussi <cristian.marussi at arm.com>
---
drivers/firmware/arm_scmi/bus.c | 141 ++++++++++++++++++++++++++---
drivers/firmware/arm_scmi/common.h | 8 +-
drivers/firmware/arm_scmi/driver.c | 9 +-
include/linux/scmi_protocol.h | 5 -
4 files changed, 141 insertions(+), 22 deletions(-)
diff --git a/drivers/firmware/arm_scmi/bus.c b/drivers/firmware/arm_scmi/bus.c
index 61113def5a9a..190999a658b2 100644
--- a/drivers/firmware/arm_scmi/bus.c
+++ b/drivers/firmware/arm_scmi/bus.c
@@ -7,6 +7,7 @@
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/atomic.h>
#include <linux/types.h>
#include <linux/module.h>
#include <linux/of.h>
@@ -30,6 +31,9 @@ struct scmi_requested_dev {
struct list_head node;
};
+/* Track globally the creation of SCMI SystemPower related devices */
+static atomic_t scmi_syspower_registered = ATOMIC_INIT(0);
+
/**
* scmi_protocol_device_request - Helper to request a device
*
@@ -213,11 +217,11 @@ static int scmi_match_by_id_table(struct device *dev, void *data)
struct scmi_device_id *id_table = data;
return sdev->protocol_id == id_table->protocol_id &&
- !strcmp(sdev->name, id_table->name);
+ (id_table->name && !strcmp(sdev->name, id_table->name));
}
-struct scmi_device *scmi_child_dev_find(struct device *parent,
- int prot_id, const char *name)
+static struct scmi_device *scmi_child_dev_find(struct device *parent,
+ int prot_id, const char *name)
{
struct scmi_device_id id_table;
struct device *dev;
@@ -297,13 +301,53 @@ static void scmi_device_release(struct device *dev)
kfree(to_scmi_dev(dev));
}
-struct scmi_device *
-scmi_device_create(struct device_node *np, struct device *parent, int protocol,
- const char *name)
+static void __scmi_device_destroy(struct scmi_device *scmi_dev)
+{
+ pr_debug("(%s) Destroying SCMI device '%s' for protocol 0x%x (%s)\n",
+ of_node_full_name(scmi_dev->dev.parent->of_node),
+ dev_name(&scmi_dev->dev), scmi_dev->protocol_id,
+ scmi_dev->name);
+
+ if (scmi_dev->protocol_id == SCMI_PROTOCOL_SYSTEM)
+ atomic_set(&scmi_syspower_registered, 0);
+
+ kfree_const(scmi_dev->name);
+ ida_free(&scmi_bus_id, scmi_dev->id);
+ device_unregister(&scmi_dev->dev);
+}
+
+static struct scmi_device *
+__scmi_device_create(struct device_node *np, struct device *parent,
+ int protocol, const char *name)
{
int id, retval;
struct scmi_device *scmi_dev;
+ /*
+ * If the same protocol/name device already exist under the same parent
+ * (i.e. SCMI instance) just return the existent device.
+ * This avoids any race between the SCMI driver, creating devices for
+ * each DT defined protocol at probe time, and the concurrent
+ * registration of SCMI drivers.
+ */
+ scmi_dev = scmi_child_dev_find(parent, protocol, name);
+ if (scmi_dev)
+ return scmi_dev;
+
+ /*
+ * Ignore any possible subsequent failures while creating the device
+ * since we are doomed anyway at that point; not using a mutex which
+ * spans across this whole function to keep things simple and to avoid
+ * to serialize all the __scmi_device_create calls across possibly
+ * different SCMI server instances (parent)
+ */
+ if (protocol == SCMI_PROTOCOL_SYSTEM &&
+ atomic_cmpxchg(&scmi_syspower_registered, 0, 1)) {
+ dev_warn(parent,
+ "SCMI SystemPower protocol device must be unique !\n");
+ return NULL;
+ }
+
scmi_dev = kzalloc(sizeof(*scmi_dev), GFP_KERNEL);
if (!scmi_dev)
return NULL;
@@ -333,6 +377,10 @@ scmi_device_create(struct device_node *np, struct device *parent, int protocol,
if (retval)
goto put_dev;
+ pr_debug("(%s) Created SCMI device '%s' for protocol 0x%x (%s)\n",
+ of_node_full_name(parent->of_node),
+ dev_name(&scmi_dev->dev), protocol, name);
+
return scmi_dev;
put_dev:
kfree_const(scmi_dev->name);
@@ -341,18 +389,85 @@ scmi_device_create(struct device_node *np, struct device *parent, int protocol,
return NULL;
}
-void scmi_device_destroy(struct scmi_device *scmi_dev)
+/**
+ * scmi_device_create - A method to create one or more SCMI devices
+ *
+ * @np: A reference to the device node to use for the new device(s)
+ * @parent: The parent device to use identifying a specific SCMI instance
+ * @protocol: The SCMI protocol to be associated with this device
+ * @name: The requested-name of the device to be created; this is optional
+ * and if no @name is provided, all the devices currently known to
+ * be requested on the SCMI bus for @protocol will be created.
+ *
+ * This method can be invoked to create a single well-defined device (like
+ * a transport device or a device requested by an SCMI driver loaded after
+ * the core SCMI stack has been probed), or to create all the devices currently
+ * known to have been requested by the loaded SCMI drivers for a specific
+ * protocol (typically during SCMI core protocol enumeration at probe time).
+ *
+ * Return: The created device (or one of them if @name was NOT provided and
+ * multiple devices were created) or NULL if no device was created;
+ * note that NULL indicates an error ONLY in case a specific @name
+ * was provided: when @name param was not provided, a number of devices
+ * could have been potentially created for a whole protocol, unless no
+ * device was found to have been requested for that specific protocol.
+ */
+struct scmi_device *scmi_device_create(struct device_node *np,
+ struct device *parent, int protocol,
+ const char *name)
{
- kfree_const(scmi_dev->name);
- ida_free(&scmi_bus_id, scmi_dev->id);
- device_unregister(&scmi_dev->dev);
+ struct list_head *phead;
+ struct scmi_requested_dev *rdev;
+ struct scmi_device *scmi_dev = NULL;
+
+ if (name)
+ return __scmi_device_create(np, parent, protocol, name);
+
+ 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 scmi_dev;
+ }
+
+ /* Walk the list of requested devices for protocol and create them */
+ list_for_each_entry(rdev, phead, node) {
+ struct scmi_device *sdev;
+
+ sdev = __scmi_device_create(np, parent,
+ rdev->id_table->protocol_id,
+ rdev->id_table->name);
+ /* Report errors and carry on... */
+ if (sdev)
+ scmi_dev = sdev;
+ else
+ pr_err("(%s) Failed to create device for protocol 0x%x (%s)\n",
+ of_node_full_name(parent->of_node),
+ rdev->id_table->protocol_id,
+ rdev->id_table->name);
+ }
+ mutex_unlock(&scmi_requested_devices_mtx);
+
+ return scmi_dev;
}
+EXPORT_SYMBOL_GPL(scmi_device_create);
+
+void scmi_device_destroy(struct device *parent, int protocol, const char *name)
+{
+ struct scmi_device *scmi_dev;
+
+ scmi_dev = scmi_child_dev_find(parent, protocol, name);
+ if (scmi_dev)
+ __scmi_device_destroy(scmi_dev);
+}
+EXPORT_SYMBOL_GPL(scmi_device_destroy);
static int __scmi_devices_unregister(struct device *dev, void *data)
{
struct scmi_device *scmi_dev = to_scmi_dev(dev);
- scmi_device_destroy(scmi_dev);
+ __scmi_device_destroy(scmi_dev);
return 0;
}
@@ -374,6 +489,10 @@ int __init scmi_bus_init(void)
void __exit scmi_bus_exit(void)
{
+ /*
+ * Destroy all remaining devices: just in case the drivers were
+ * manually unbound and at first and then the modules unloaded.
+ */
scmi_devices_unregister();
bus_unregister(&scmi_bus_type);
ida_destroy(&scmi_bus_id);
diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
index 07d34954c060..19726a037991 100644
--- a/drivers/firmware/arm_scmi/common.h
+++ b/drivers/firmware/arm_scmi/common.h
@@ -107,6 +107,11 @@ extern struct bus_type scmi_bus_type;
#define SCMI_BUS_NOTIFY_DEVICE_UNREQUEST 1
extern struct blocking_notifier_head scmi_requested_devices_nh;
+struct scmi_device *scmi_device_create(struct device_node *np,
+ struct device *parent, int protocol,
+ const char *name);
+void scmi_device_destroy(struct device *parent, int protocol, const char *name);
+
int scmi_protocol_acquire(const struct scmi_handle *handle, u8 protocol_id);
void scmi_protocol_release(const struct scmi_handle *handle, u8 protocol_id);
@@ -168,9 +173,6 @@ struct scmi_transport_ops {
bool (*poll_done)(struct scmi_chan_info *cinfo, struct scmi_xfer *xfer);
};
-struct scmi_device *scmi_child_dev_find(struct device *parent,
- int prot_id, const char *name);
-
/**
* struct scmi_desc - Description of SoC integration
*
diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 8591b2c740c6..83a43a5f7bb4 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -2091,6 +2091,8 @@ static int scmi_chan_setup(struct scmi_info *info, struct device_node *of_node,
/* Create a uniquely named, dedicated transport device for this chan */
tdev = scmi_device_create(of_node, info->dev, prot_id, name);
if (!tdev) {
+ dev_err(info->dev,
+ "failed to create transport device (%s)\n", name);
devm_kfree(info->dev, cinfo);
return -EINVAL;
}
@@ -2100,7 +2102,7 @@ static int scmi_chan_setup(struct scmi_info *info, struct device_node *of_node,
ret = info->desc->ops->chan_setup(cinfo, info->dev, tx);
if (ret) {
of_node_put(of_node);
- scmi_device_destroy(tdev);
+ scmi_device_destroy(info->dev, prot_id, name);
devm_kfree(info->dev, cinfo);
return ret;
}
@@ -2123,7 +2125,7 @@ static int scmi_chan_setup(struct scmi_info *info, struct device_node *of_node,
/* Destroy channel and device only if created by this call. */
if (tdev) {
of_node_put(of_node);
- scmi_device_destroy(tdev);
+ scmi_device_destroy(info->dev, prot_id, name);
devm_kfree(info->dev, cinfo);
}
return ret;
@@ -2202,10 +2204,11 @@ static int scmi_chan_destroy(int id, void *p, void *idr)
struct scmi_chan_info *cinfo = p;
if (cinfo->dev) {
+ struct scmi_info *info = handle_to_scmi_info(cinfo->handle);
struct scmi_device *sdev = to_scmi_dev(cinfo->dev);
of_node_put(cinfo->dev->of_node);
- scmi_device_destroy(sdev);
+ scmi_device_destroy(info->dev, id, sdev->name);
cinfo->dev = NULL;
}
diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
index 4f765bc788ff..0ce5746a4470 100644
--- a/include/linux/scmi_protocol.h
+++ b/include/linux/scmi_protocol.h
@@ -804,11 +804,6 @@ struct scmi_device {
#define to_scmi_dev(d) container_of(d, struct scmi_device, dev)
-struct scmi_device *
-scmi_device_create(struct device_node *np, struct device *parent, int protocol,
- const char *name);
-void scmi_device_destroy(struct scmi_device *scmi_dev);
-
struct scmi_device_id {
u8 protocol_id;
const char *name;
--
2.34.1
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