Paul Fulghum <[email protected]> wrote:
>
> Add driver support for general purpose I/O feature
> of the Synclink GT adapters.
>
>
> ...
>
> /*
> + * conditional wait facility
> + */
> +struct cond_wait {
> + struct cond_wait *next;
> + wait_queue_head_t q;
> + wait_queue_t wait;
> + unsigned int data;
> +};
> +static void init_cond_wait(struct cond_wait *w, unsigned int data);
> +static void add_cond_wait(struct cond_wait **head, struct cond_wait *w);
> +static void remove_cond_wait(struct cond_wait **head, struct cond_wait *w);
> +static void flush_cond_wait(struct cond_wait **head);
Adding new generic-looking infrastructure into a driver is a worry. Either
we're missing some facility, or the driver is doing something unnecessary
or the driver's requirements are unique.
Tell use more about conditional waits?
> ...
> +static int wait_gpio(struct slgt_info *info, struct gpio_desc __user *user_gpio)
> +{
> + unsigned long flags;
> + int rc = 0;
> + struct gpio_desc gpio;
> + struct cond_wait wait;
> + u32 state;
> +
> + if (!info->gpio_present)
> + return -EINVAL;
> + if (copy_from_user(&gpio, user_gpio, sizeof(gpio)))
> + return -EFAULT;
> + DBGINFO(("%s wait_gpio() state=%08x smask=%08x\n",
> + info->device_name, gpio.state, gpio.smask));
> + /* ignore output pins identified by set IODR bit */
> + if ((gpio.smask &= ~rd_reg32(info, IODR)) == 0)
> + return -EINVAL;
> + init_cond_wait(&wait, gpio.smask);
> +
> + spin_lock_irqsave(&info->lock, flags);
> + /* enable interrupts for watched pins */
> + wr_reg32(info, IOER, rd_reg32(info, IOER) | gpio.smask);
> + /* get current pin states */
> + state = rd_reg32(info, IOVR);
> +
> + if (gpio.smask & ~(state ^ gpio.state)) {
> + /* already in target state */
> + gpio.state = state;
> + } else {
> + /* wait for target state */
> + add_cond_wait(&info->gpio_wait_q, &wait);
> + spin_unlock_irqrestore(&info->lock, flags);
> + schedule();
> + if (signal_pending(current))
> + rc = -ERESTARTSYS;
> + else
> + gpio.state = wait.data;
> + spin_lock_irqsave(&info->lock, flags);
> + remove_cond_wait(&info->gpio_wait_q, &wait);
> + }
> +
> + /* disable all GPIO interrupts if no waiting processes */
> + if (info->gpio_wait_q == NULL)
> + wr_reg32(info, IOER, 0);
Should we be dong that write if rc!=0? I guess so..
> + spin_unlock_irqrestore(&info->lock,flags);
> +
> + if ((rc == 0) && copy_to_user(user_gpio, &gpio, sizeof(gpio)))
> + rc = -EFAULT;
> + return rc;
> +}
-
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