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Date: Wed, 23 Sep 2020 19:14:43 +0300
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Kent Gibson <warthog618@...il.com>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
"open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
Bartosz Golaszewski <bgolaszewski@...libre.com>,
Linus Walleij <linus.walleij@...aro.org>,
Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH v9 10/20] gpiolib: cdev: support GPIO_V2_LINE_SET_CONFIG_IOCTL
On Tue, Sep 22, 2020 at 5:35 AM Kent Gibson <warthog618@...il.com> wrote:
>
> Add support for GPIO_V2_LINE_SET_CONFIG_IOCTL, the uAPI v2
> line set config ioctl.
>
> Signed-off-by: Kent Gibson <warthog618@...il.com>
> ---
> drivers/gpio/gpiolib-cdev.c | 88 +++++++++++++++++++++++++++++++++++++
> 1 file changed, 88 insertions(+)
>
> diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
> index 145bda2151fb..debd3b277523 100644
> --- a/drivers/gpio/gpiolib-cdev.c
> +++ b/drivers/gpio/gpiolib-cdev.c
> @@ -16,6 +16,7 @@
> #include <linux/kernel.h>
> #include <linux/kfifo.h>
> #include <linux/module.h>
> +#include <linux/mutex.h>
> #include <linux/pinctrl/consumer.h>
> #include <linux/poll.h>
> #include <linux/spinlock.h>
> @@ -444,6 +445,8 @@ struct line {
> * @seqno: the sequence number for edge events generated on all lines in
> * this line request. Note that this is not used when @num_lines is 1, as
> * the line_seqno is then the same and is cheaper to calculate.
> + * @config_mutex: mutex for serializing ioctl() calls to ensure consistency
> + * of configuration, particularly multi-step accesses to desc flags.
> * @lines: the lines held by this line request, with @num_lines elements.
> */
> struct linereq {
> @@ -454,6 +457,7 @@ struct linereq {
> u32 event_buffer_size;
> DECLARE_KFIFO_PTR(events, struct gpio_v2_line_event);
> atomic_t seqno;
> + struct mutex config_mutex;
> struct line lines[];
> };
>
> @@ -573,6 +577,8 @@ static void edge_detector_stop(struct line *line)
> free_irq(line->irq, line);
> line->irq = 0;
> }
> +
> + line->eflags = 0;
> }
>
> static int edge_detector_setup(struct line *line,
> @@ -614,6 +620,17 @@ static int edge_detector_setup(struct line *line,
> return 0;
> }
>
> +static int edge_detector_update(struct line *line, u64 eflags,
> + bool polarity_change)
> +{
> + if ((line->eflags == eflags) && !polarity_change)
> + return 0;
> +
> + edge_detector_stop(line);
> +
> + return edge_detector_setup(line, eflags);
> +}
> +
> static u64 gpio_v2_line_config_flags(struct gpio_v2_line_config *lc,
> unsigned int line_idx)
> {
> @@ -796,6 +813,74 @@ static long linereq_get_values(struct linereq *lr, void __user *ip)
> return 0;
> }
>
> +static long linereq_set_config_unlocked(struct linereq *lr,
> + struct gpio_v2_line_config *lc)
> +{
> + struct gpio_desc *desc;
> + unsigned int i;
> + u64 flags;
> + bool polarity_change;
> + int ret;
> +
> + for (i = 0; i < lr->num_lines; i++) {
> + desc = lr->lines[i].desc;
> + flags = gpio_v2_line_config_flags(lc, i);
> + polarity_change =
> + (test_bit(FLAG_ACTIVE_LOW, &desc->flags) !=
> + ((flags & GPIO_V2_LINE_FLAG_ACTIVE_LOW) != 0));
Comparison
> +
> + gpio_v2_line_config_flags_to_desc_flags(flags, &desc->flags);
> + /*
> + * Lines have to be requested explicitly for input
> + * or output, else the line will be treated "as is".
> + */
> + if (flags & GPIO_V2_LINE_FLAG_OUTPUT) {
> + int val = gpio_v2_line_config_output_value(lc, i);
> +
> + edge_detector_stop(&lr->lines[i]);
> + ret = gpiod_direction_output(desc, val);
> + if (ret)
> + return ret;
> + } else if (flags & GPIO_V2_LINE_FLAG_INPUT) {
> + ret = gpiod_direction_input(desc);
> + if (ret)
> + return ret;
> +
> + ret = edge_detector_update(&lr->lines[i],
> + flags & GPIO_V2_LINE_EDGE_FLAGS,
> + polarity_change);
> + if (ret)
> + return ret;
> + }
> +
> + blocking_notifier_call_chain(&desc->gdev->notifier,
> + GPIO_V2_LINE_CHANGED_CONFIG,
> + desc);
> + }
> + return 0;
> +}
> +
> +static long linereq_set_config(struct linereq *lr, void __user *ip)
> +{
> + struct gpio_v2_line_config lc;
> + int ret;
> +
> + if (copy_from_user(&lc, ip, sizeof(lc)))
> + return -EFAULT;
> +
> + ret = gpio_v2_line_config_validate(&lc, lr->num_lines);
> + if (ret)
> + return ret;
> +
> + mutex_lock(&lr->config_mutex);
> +
> + ret = linereq_set_config_unlocked(lr, &lc);
> +
> + mutex_unlock(&lr->config_mutex);
> +
> + return ret;
> +}
> +
> static long linereq_ioctl(struct file *file, unsigned int cmd,
> unsigned long arg)
> {
> @@ -804,6 +889,8 @@ static long linereq_ioctl(struct file *file, unsigned int cmd,
>
> if (cmd == GPIO_V2_LINE_GET_VALUES_IOCTL)
> return linereq_get_values(lr, ip);
> + else if (cmd == GPIO_V2_LINE_SET_CONFIG_IOCTL)
> + return linereq_set_config(lr, ip);
>
> return -EINVAL;
> }
> @@ -964,6 +1051,7 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip)
> }
> }
>
> + mutex_init(&lr->config_mutex);
> init_waitqueue_head(&lr->wait);
> lr->event_buffer_size = ulr.event_buffer_size;
> if (lr->event_buffer_size == 0)
> --
> 2.28.0
>
--
With Best Regards,
Andy Shevchenko
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