On Wed, Jan 10, 2018 at 6:47 PM, Anup Patel <a...@brainfault.org> wrote:
> 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>
> ---
> Documentation/ABI/testing/sysfs-bus-rpmsg | 20 ++++++++++++++
> drivers/rpmsg/rpmsg_core.c | 46
> +++++++++++++++++++++++++++++--
> 2 files changed, 64 insertions(+), 2 deletions(-)
>
> 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: January 2018
> +KernelVersion: 4.16
> +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 dffa3aa..9a25e42 100644
> --- a/drivers/rpmsg/rpmsg_core.c
> +++ b/drivers/rpmsg/rpmsg_core.c
> @@ -321,11 +321,11 @@ struct device *rpmsg_find_device(struct device *parent,
> }
> EXPORT_SYMBOL(rpmsg_find_device);
>
> -/* sysfs show configuration fields */
> +/* sysfs configuration fields */
> #define rpmsg_show_attr(field, path, format_string) \
> static ssize_t \
> field##_show(struct device *dev, \
> - struct device_attribute *attr, char *buf) \
> + struct device_attribute *attr, char *buf) \
> { \
> struct rpmsg_device *rpdev = to_rpmsg_device(dev); \
> \
> @@ -333,11 +333,52 @@ field##_show(struct device *dev,
> \
> } \
> static DEVICE_ATTR_RO(field);
>
> +#define rpmsg_string_attr(field, path) \
> +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, *cp; \
> + \
> + new = kstrndup(buf, sz, GFP_KERNEL); \
> + if (!new) \
> + return -ENOMEM; \
> + \
> + cp = strchr(new, '\n'); \
> + if (cp) \
> + *cp = '\0'; \
> + \
> + device_lock(dev); \
> + old = rpdev->path; \
> + if (strlen(new)) { \
> + rpdev->path = new; \
> + } else { \
> + kfree(new); \
> + rpdev->path = 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->path); \
> +} \
> +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 +400,7 @@ 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
>
Hi All,
Any comments on this??
Regards,
Anup
