Hi Mathieu,
On 5/4/20 11:58 PM, Mathieu Poirier wrote:
> After adding support for rpmsg device name extension, this patch
> provides a function that returns the extension portion of an rpmsg
> device name. That way users of the name extension functionality don't
> have to write the same boiler plate code to extract the information.
I do not test it yet,but LGTM.
I plan to use these patches for the rpmsg_tty.
Please find few remarks below.
>
> Suggested-by: Suman Anna <s-anna@xxxxxx>;
> Signed-off-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
> ---
> drivers/rpmsg/rpmsg_core.c | 92 ++++++++++++++++++++++++++++++++++++++
> include/linux/rpmsg.h | 13 ++++++
> 2 files changed, 105 insertions(+)
>
> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> index 5e01e8dede6b..dae87c0cb73d 100644
> --- a/drivers/rpmsg/rpmsg_core.c
> +++ b/drivers/rpmsg/rpmsg_core.c
> @@ -439,6 +439,98 @@ static int rpmsg_dev_match(struct device *dev, struct device_driver *drv)
> return of_driver_match_device(dev, drv);
> }
>
> +/**
> + * rpmsg_device_get_name_extension() - get the name extension of a rpmsg device
> + * @rpdev: the rpmsg device to work with
> + * @skip: how many characters in the extension should be skipped over
> + *
> + * With function rpmsg_id_match() allowing for extension of the base driver name
> + * in order to differentiate services, this function returns the extension part
> + * of an rpmsg device name. As such and with the following rpmsg driver device
> + * id table and rpmsg device names:
> + *
> + * static struct rpmsg_device_id rpmsg_driver_sample_id_table[] = {
> + * { .name = "rpmsg-client-sample" },
> + * { },
> + * }
> + *
> + * rpdev1->id.name == "rpmsg-client-sample";
> + * rpdev2->id.name == "rpmsg-client-sample_instance0";
> + *
> + * Calling rpmsg_device_get_name_extension() will yields the following:
> + *
> + * rpmsg_device_get_name_extension(rpdev1, 0) == NULL;
> + * rpmsg_device_get_name_extension(rpdev2, 0) == "_instance0";
> + * rpmsg_device_get_name_extension(rpdev2, 1) == "instance0";
> + *
> + *
> + * Note: The name extension should be free'd using kfree_const().
> + *
> + * Return: the name extension if found, NULL if not found and an error
> + * code otherwise.
> + */
> +const char *rpmsg_device_get_name_extension(struct rpmsg_device *rpdev,
> + unsigned int skip)
> +{
> + const char *drv_name, *dev_name, *extension;
> + const struct rpmsg_device_id *ids;
> + struct device *dev = &rpdev->dev;
> + struct rpmsg_driver *rpdrv;
> + bool match = false;
> + unsigned int i;
> +
> + if (!dev->driver)
> + return ERR_PTR(-EINVAL);
> +
> + rpdrv = to_rpmsg_driver(dev->driver);
> +
> + /*
> + * No point in going further if the device and the driver don't
> + * have a name or a table to work with.
> + */
> + if (!rpdev->id.name[0] || !rpdrv->id_table)
> + return ERR_PTR(-EINVAL);
> +
> + ids = rpdrv->id_table;
> + dev_name = rpdev->id.name;
> +
> + /*
> + * See if any name in the driver's table match the beginning
> + * of the rpmsg device's name.
> + */
> + for (i = 0; ids[i].name[0]; i++) {
> + drv_name = ids[i].name;
> + if (strncmp(drv_name,
> + dev_name, strlen(drv_name)) == 0) {
> + match = true;
> + break;
> + }
> + }
> +
> + if (!match)
> + return NULL;
here i would return an error to differentiate unmatch and name without extension.
> +
> + /* No name extension to return if device and driver are the same */
> + if (strlen(dev_name) == strlen(drv_name))
> + return NULL;
> +
> + /*
> + * Make sure we were not requested to skip past the end
> + * of the device name.
> + */
> + if (strlen(drv_name) + skip >= strlen(dev_name))
> + return ERR_PTR(-EINVAL);
> +
> + /*
> + * Move past the base name published by the driver and
> + * skip any extra characters if needed.
> + */
> + extension = dev_name + strlen(drv_name) + skip;
> +
> + return kstrdup_const(extension, GFP_KERNEL);
what about just returning the extension pointer?
rpdev->id.name should be valid until device is unregistered.
Regards
Arnaud
> +}
> +EXPORT_SYMBOL(rpmsg_device_get_name_extension);
> +
> static int rpmsg_uevent(struct device *dev, struct kobj_uevent_env *env)
> {
> struct rpmsg_device *rpdev = to_rpmsg_device(dev);
> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
> index 9fe156d1c018..9537b95ad30a 100644
> --- a/include/linux/rpmsg.h
> +++ b/include/linux/rpmsg.h
> @@ -135,6 +135,9 @@ int rpmsg_trysend_offchannel(struct rpmsg_endpoint *ept, u32 src, u32 dst,
> __poll_t rpmsg_poll(struct rpmsg_endpoint *ept, struct file *filp,
> poll_table *wait);
>
> +const char *rpmsg_device_get_name_extension(struct rpmsg_device *dev,
> + unsigned int skip);
> +
> #else
>
> static inline int register_rpmsg_device(struct rpmsg_device *dev)
> @@ -242,6 +245,16 @@ static inline __poll_t rpmsg_poll(struct rpmsg_endpoint *ept,
> return 0;
> }
>
> +static inline
> +const char *rpmsg_device_get_name_extension(struct rpmsg_device *dev,
> + unsigned int skip)
> +{
> + /* This shouldn't be possible */
> + WARN_ON(1);
> +
> + return NULL;
> +}
> +
> #endif /* IS_ENABLED(CONFIG_RPMSG) */
>
> /* use a macro to avoid include chaining to get THIS_MODULE */
>
