This patch adds "driver_override" device attribute for rpmsg_device which
will allow users to explicitly specify the rpmsg_driver to be used via
sysfs entry.
The "driver_override" device attribute implemented here is very similar
to "driver_override" implemented for platform, pci, and amba bus types.
One important use-case of "driver_override" device attribute is to force
use of rpmsg_chrdev driver for certain rpmsg_device instances.
Signed-off-by: Anup Patel <a...@brainfault.org>
Changes since v1:
- Removed un-related changes from patch
- Renamed "path" to "member" in rpmsg_string_attr() macro
- Used strcspn() instead of strchr() in rpmsg_string_attr() macro
---
Documentation/ABI/testing/sysfs-bus-rpmsg | 20 ++++++++++++++++
drivers/rpmsg/rpmsg_core.c | 39 +++++++++++++++++++++++++++++++
2 files changed, 59 insertions(+)
diff --git a/Documentation/ABI/testing/sysfs-bus-rpmsg
b/Documentation/ABI/testing/sysfs-bus-rpmsg
index 189e419..1c8599e 100644
--- a/Documentation/ABI/testing/sysfs-bus-rpmsg
+++ b/Documentation/ABI/testing/sysfs-bus-rpmsg
@@ -73,3 +73,23 @@ Description:
This sysfs entry tells us whether the channel is a local
server channel that is announced (values are either
true or false).
+
+What: /sys/bus/rpmsg/devices/.../driver_override
+Date: March 2018
+KernelVersion: 4.17
+Contact: Ohad Ben-Cohen <o...@wizery.com>
+Description:
+ Every rpmsg device is a communication channel with a remote
+ processor. Channels are identified by a textual name (see
+ /sys/bus/rpmsg/devices/.../name above) and have a local
+ ("source") rpmsg address, and remote ("destination") rpmsg
+ address.
+
+ The listening entity (or client) which communicates with a
+ remote processor is referred as rpmsg driver. The rpmsg device
+ and rpmsg driver are matched based on rpmsg device name and
+ rpmsg driver ID table.
+
+ This sysfs entry allows the rpmsg driver for a rpmsg device
+ to be specified which will override standard OF, ID table
+ and name matching.
diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
index 5a08176..3e71976 100644
--- a/drivers/rpmsg/rpmsg_core.c
+++ b/drivers/rpmsg/rpmsg_core.c
@@ -333,11 +333,49 @@ field##_show(struct device *dev,
\
} \
static DEVICE_ATTR_RO(field);
+#define rpmsg_string_attr(field, member) \
+static ssize_t \
+field##_store(struct device *dev, struct device_attribute *attr, \
+ const char *buf, size_t sz) \
+{ \
+ struct rpmsg_device *rpdev = to_rpmsg_device(dev); \
+ char *new, *old; \
+ \
+ new = kstrndup(buf, sz, GFP_KERNEL); \
+ if (!new) \
+ return -ENOMEM; \
+ new[strcspn(new, "\n")] = '\0'; \
+ \
+ device_lock(dev); \
+ old = rpdev->member; \
+ if (strlen(new)) { \
+ rpdev->member = new; \
+ } else { \
+ kfree(new); \
+ rpdev->member = NULL; \
+ } \
+ device_unlock(dev); \
+ \
+ kfree(old); \
+ \
+ return sz; \
+} \
+static ssize_t \
+field##_show(struct device *dev, \
+ struct device_attribute *attr, char *buf) \
+{ \
+ struct rpmsg_device *rpdev = to_rpmsg_device(dev); \
+ \
+ return sprintf(buf, "%s\n", rpdev->member); \
+} \
+static DEVICE_ATTR_RW(field)
+
/* for more info, see Documentation/ABI/testing/sysfs-bus-rpmsg */
rpmsg_show_attr(name, id.name, "%s\n");
rpmsg_show_attr(src, src, "0x%x\n");
rpmsg_show_attr(dst, dst, "0x%x\n");
rpmsg_show_attr(announce, announce ? "true" : "false", "%s\n");
+rpmsg_string_attr(driver_override, driver_override);
static ssize_t modalias_show(struct device *dev,
struct device_attribute *attr, char *buf)
@@ -359,6 +397,7 @@ static struct attribute *rpmsg_dev_attrs[] = {
&dev_attr_dst.attr,
&dev_attr_src.attr,
&dev_attr_announce.attr,
+ &dev_attr_driver_override.attr,
NULL,
};
ATTRIBUTE_GROUPS(rpmsg_dev);
--
2.7.4
