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rpmsg: Add driver_override device attribute for rpmsg_device

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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 <anup@brainfault.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
This commit is contained in:
Anup Patel 2018-03-23 21:41:17 +05:30 • committed by Bjorn Andersson
parent 60cc43fc88
commit 39e47767ec
2 changed files with 59 additions and 0 deletions
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20
Documentation/ABI/testing/sysfs-bus-rpmsg
View file

@ -73,3 +73,23 @@ Description:
This sysfs entry tells us whether the channel is a local This sysfs entry tells us whether the channel is a local
server channel that is announced (values are either server channel that is announced (values are either
true or false). true or false).
What: /sys/bus/rpmsg/devices/.../driver_override
Date: April 2018
KernelVersion: 4.18
Contact: Bjorn Andersson <bjorn.andersson@linaro.org>
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.

39
drivers/rpmsg/rpmsg_core.c
View file

@ -333,11 +333,49 @@ field##_show(struct device *dev, \
} \ } \
static DEVICE_ATTR_RO(field); 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 */ /* for more info, see Documentation/ABI/testing/sysfs-bus-rpmsg */
rpmsg_show_attr(name, id.name, "%s\n"); rpmsg_show_attr(name, id.name, "%s\n");
rpmsg_show_attr(src, src, "0x%x\n"); rpmsg_show_attr(src, src, "0x%x\n");
rpmsg_show_attr(dst, dst, "0x%x\n"); rpmsg_show_attr(dst, dst, "0x%x\n");
rpmsg_show_attr(announce, announce ? "true" : "false", "%s\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, static ssize_t modalias_show(struct device *dev,
struct device_attribute *attr, char *buf) struct device_attribute *attr, char *buf)
@ -359,6 +397,7 @@ static struct attribute *rpmsg_dev_attrs[] = {
&dev_attr_dst.attr, &dev_attr_dst.attr,
&dev_attr_src.attr, &dev_attr_src.attr,
&dev_attr_announce.attr, &dev_attr_announce.attr,
&dev_attr_driver_override.attr,
NULL, NULL,
}; };
ATTRIBUTE_GROUPS(rpmsg_dev); ATTRIBUTE_GROUPS(rpmsg_dev);