[PATCH 1/4 v4] drivers: create a pin control subsystem
Stijn Devriendt
highguy at gmail.com
Fri Sep 2 03:02:32 EDT 2011
On Fri, Aug 19, 2011 at 11:53 AM, Linus Walleij
<linus.walleij at stericsson.com> wrote:
> +
> +/**
> + * pin_request() - request a single pin to be muxed in, typically for GPIO
> + * @pin: the pin number in the global pin space
> + * @function: a functional name to give to this pin, passed to the driver
> + * so it knows what function to mux in, e.g. the string "gpioNN"
> + * means that you want to mux in the pin for use as GPIO number NN
> + * @gpio: if this request concerns a single GPIO pin
> + */
> +static int pin_request(struct pinctrl_dev *pctldev,
> + int pin, const char *function, bool gpio)
> +{
> + struct pin_desc *desc;
> + const struct pinmux_ops *ops;
> + int status = -EINVAL;
> +
> + pr_debug("request pin %d for %s\n", pin, function);
> +
> + if (!pin_is_valid(pctldev, pin)) {
> + pr_err("pin is invalid\n");
> + return -EINVAL;
> + }
> +
> + if (!function) {
> + pr_err("no function name given\n");
> + return -EINVAL;
> + }
> +
> + desc = pin_desc_get(pctldev, pin);
> + if (desc == NULL) {
> + pr_err("pin is not registered so it cannot be requested\n");
> + goto out;
> + }
> + if (desc->mux_requested) {
> + pr_err("pin already requested\n");
> + goto out;
> + }
Isn't locking missing here?
> + ops = pctldev->desc->pmxops;
> +
> + /* Let each pin increase references to this module */
> + if (!try_module_get(pctldev->owner)) {
> + pr_err("could not increase module refcount for pin %d\n", pin);
> + status = -EINVAL;
> + goto out;
> + }
> +
> + /*
> + * If there is no kind of request function for the pin we just assume
> + * we got it by default and proceed.
> + */
> + if (gpio && ops->gpio_request_enable)
> + /* This requests and enables a single GPIO pin */
> + status = ops->gpio_request_enable(pctldev, pin);
> + else if (ops->request)
> + status = ops->request(pctldev, pin);
> + else
> + status = 0;
> +
> + if (status) {
> + pr_err("->request on device %s failed "
> + "for pin %d\n",
> + pctldev->desc->name, pin);
> + goto out;
> + }
> +
> + desc->mux_requested = true;
> + strncpy(desc->mux_function, function, sizeof(desc->mux_function));
> +
> +out:
> + if (status)
> + pr_err("pin-%d (%s) status %d\n",
> + pin, function ? : "?", status);
> +
> + return status;
> +}
> +
Regards,
Stijn
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