Messages in this thread |  | | Date | Wed, 8 Jan 2020 14:46:50 +0200 | From | Andy Shevchenko <> | Subject | Re: [PATCH v4 12/13] gpiolib: add new ioctl() for monitoring changes in line info |
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On Tue, Dec 24, 2019 at 01:07:08PM +0100, Bartosz Golaszewski wrote: > From: Bartosz Golaszewski <bgolaszewski@baylibre.com> > > Currently there is no way for user-space to be informed about changes > in status of GPIO lines e.g. when someone else requests the line or its > config changes. We can only periodically re-read the line-info. This > is fine for simple one-off user-space tools, but any daemon that provides > a centralized access to GPIO chips would benefit hugely from an event > driven line info synchronization. > > This patch adds a new ioctl() that allows user-space processes to reuse > the file descriptor associated with the character device for watching > any changes in line properties. Every such event contains the updated > line information. > > Currently the events are generated on three types of status changes: when > a line is requested, when it's released and when its config is changed. > The first two are self-explanatory. For the third one: this will only > happen when another user-space process calls the new SET_CONFIG ioctl() > as any changes that can happen from within the kernel (i.e. > set_transitory() or set_debounce()) are of no interest to user-space.
...
> - } else if (cmd == GPIO_GET_LINEINFO_IOCTL) { > + } else if (cmd == GPIO_GET_LINEINFO_IOCTL || > + cmd == GPIO_GET_LINEINFO_WATCH_IOCTL) {
What about to split the functionality to something like lineinfo_get() and...
> struct gpioline_info lineinfo;
> - struct gpio_desc *desc;
Hmm... Is it correct patch for this change?
> > if (copy_from_user(&lineinfo, ip, sizeof(lineinfo))) > return -EFAULT; > @@ -1246,11 +1260,25 @@ static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) > > if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) > return -EFAULT; > + > + if (cmd == GPIO_GET_LINEINFO_WATCH_IOCTL) > + set_bit(desc_to_gpio(desc), priv->watched_lines); > +
...simple use
} else if (cmd == GPIO_GET_LINEINFO_IOCTL) { return lineinfo_get(); } else if {cmd == GPIO_GET_LINEINFO_WATCH_IOCTL) { ret = lineinfo_get() set_bit(); return ret; }
?
> return 0;
-- With Best Regards, Andy Shevchenko
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