lkml.org 
[lkml]   [2015]   [Aug]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH] watchdog_dev: Use device tree alias for naming watchdogs
On 08/28/2015 02:58 PM, Justin Chen wrote:
> Currently there is no way to easily differentiate multiple
> watchdog devices. The watchdogs are named by the order they
> are probed.
> 1st probed watchdog: /dev/watchdog0
> 2nd probed watchdog: /dev/watchdog1
> ...
>
> This change uses the alias of the watchdog device node for
> the name of the watchdog.
> aliases {
> watchdog0 = "/...../...."
> watchdog3 = "/..../....."
> watchdog2 = "/..../....."
> ...
> }
>
> This will translate to...
> /dev/watchdog0
> /dev/watchdog3
> /dev/watchdog2
>
> Signed-off-by: Justin Chen <justinpopo6@gmail.com>

Interesting idea. Checking through other subsystems, many others do the same,
so it makes sense to use that mechanism.

However, the id assignment should be in the calling code, in __watchdog_register_device,
to avoid that another id, possibly conflicting, is assigned through the ida mechanism.

This is a bit more complicated than it looks like to ensure correct id assignment.
Have a look into the i2c code to see how it is handled. Essentially we must pass
the requested number to ida_simple_get().

Thanks,
Guenter

> ---
> drivers/watchdog/watchdog_dev.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
> index 6aaefba..52b1f0b 100644
> --- a/drivers/watchdog/watchdog_dev.c
> +++ b/drivers/watchdog/watchdog_dev.c
> @@ -41,6 +41,7 @@
> #include <linux/miscdevice.h> /* For handling misc devices */
> #include <linux/init.h> /* For __init/__exit/... */
> #include <linux/uaccess.h> /* For copy_to_user/put_user/... */
> +#include <linux/of.h>
>
> #include "watchdog_core.h"
>
> @@ -522,7 +523,13 @@ static struct miscdevice watchdog_miscdev = {
>
> int watchdog_dev_register(struct watchdog_device *watchdog)
> {
> - int err, devno;
> + int err, devno, ret;
> +
> + if (watchdog->parent) {
> + ret = of_alias_get_id(watchdog->parent->of_node, "watchdog");
> + if (ret >= 0)
> + watchdog->id = ret;
> + }
>
> if (watchdog->id == 0) {
> old_wdd = watchdog;
>



\
 
 \ /
  Last update: 2015-08-29 12:21    [W:0.039 / U:0.560 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site