pinctrl: add explicit gpio_disable_free pinmux_op

Some pinctrl drivers (Tegra at least) program a pin to be a GPIO in a
completely different manner than they select which function to mux out of
that pin. In order to support a single "free" pinmux_op, the driver would
need to maintain a per-pin state of requested-for-gpio vs. requested-for-
function. However, that's a lot of work when the core already has explicit
separate paths for gpio request/free and function request/free.

So, add a gpio_disable_free op to struct pinmux_ops, and make pin_free()
call it when appropriate.

When doing this, I noticed that when calling pin_request():

    !!gpio == (gpio_range != NULL)

... and so I collapsed those two parameters in both pin_request(), and
when adding writing the new code in pin_free().

Also, for pin_free():

    !!free_func == (gpio_range != NULL)

However, I didn't want pin_free() to know about the GPIO function naming
special case, so instead, I reworked pin_free() to always return the pin's
previously requested function, and now pinmux_free_gpio() calls
kfree(function). This is much more balanced with the allocation having
been performed in pinmux_request_gpio().

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 25 insertions, 14 deletions

diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
index 17c3931d5ef0..c77aee5508fb 100644
--- a/drivers/pinctrl/pinmux.c
+++ b/drivers/pinctrl/pinmux.c
@@ -94,12 +94,11 @@ struct pinmux_hog {
  * @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
  * @gpio_range: the range matching the GPIO pin if this is a request for a
  *      single GPIO pin
  */
 static int pin_request(struct pinctrl_dev *pctldev,
-                       int pin, const char *function, bool gpio,
+                       int pin, const char *function,
                        struct pinctrl_gpio_range *gpio_range)
 {
         struct pin_desc *desc;
@@ -143,7 +142,7 @@ static int pin_request(struct pinctrl_dev *pctldev,
          * 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)
+        if (gpio_range && ops->gpio_request_enable)
                 /* This requests and enables a single GPIO pin */
                 status = ops->gpio_request_enable(pctldev, gpio_range, pin);
         else if (ops->request)
@@ -173,29 +172,39 @@ out:
  * pin_free() - release a single muxed in pin so something else can be muxed
  * @pctldev: pin controller device handling this pin
  * @pin: the pin to free
- * @free_func: whether to free the pin's assigned function name string
+ * @gpio_range: the range matching the GPIO pin if this is a request for a
+ *      single GPIO pin
  */
-static void pin_free(struct pinctrl_dev *pctldev, int pin, int free_func)
+static const char *pin_free(struct pinctrl_dev *pctldev, int pin,
+                            struct pinctrl_gpio_range *gpio_range)
 {
         const struct pinmux_ops *ops = pctldev->desc->pmxops;
         struct pin_desc *desc;
+        const char *func;
 
         desc = pin_desc_get(pctldev, pin);
         if (desc == NULL) {
                 dev_err(&pctldev->dev,
                         "pin is not registered so it cannot be freed\n");
-                return;
+                return NULL;
         }
 
-        if (ops->free)
+        /*
+         * If there is no kind of request function for the pin we just assume
+         * we got it by default and proceed.
+         */
+        if (gpio_range && ops->gpio_disable_free)
+                ops->gpio_disable_free(pctldev, gpio_range, pin);
+        else if (ops->free)
                 ops->free(pctldev, pin);
 
         spin_lock(&desc->lock);
-        if (free_func)
-                kfree(desc->mux_function);
+        func = desc->mux_function;
         desc->mux_function = NULL;
         spin_unlock(&desc->lock);
         module_put(pctldev->owner);
+
+        return func;
 }
 
 /**
@@ -225,7 +234,7 @@ int pinmux_request_gpio(unsigned gpio)
         if (!function)
                 return -EINVAL;
 
-        ret = pin_request(pctldev, pin, function, true, range);
+        ret = pin_request(pctldev, pin, function, range);
         if (ret < 0)
                 kfree(function);
 
@@ -243,6 +252,7 @@ void pinmux_free_gpio(unsigned gpio)
         struct pinctrl_gpio_range *range;
         int ret;
         int pin;
+        const char *func;
 
         ret = pinctrl_get_device_gpio_range(gpio, &pctldev, &range);
         if (ret)
@@ -251,7 +261,8 @@ void pinmux_free_gpio(unsigned gpio)
         /* Convert to the pin controllers number space */
         pin = gpio - range->base;
 
-        pin_free(pctldev, pin, true);
+        func = pin_free(pctldev, pin, range);
+        kfree(func);
 }
 EXPORT_SYMBOL_GPL(pinmux_free_gpio);
 
@@ -341,7 +352,7 @@ static int acquire_pins(struct pinctrl_dev *pctldev,
 
         /* Try to allocate all pins in this group, one by one */
         for (i = 0; i < num_pins; i++) {
-                ret = pin_request(pctldev, pins[i], func, false, NULL);
+                ret = pin_request(pctldev, pins[i], func, NULL);
                 if (ret) {
                         dev_err(&pctldev->dev,
                                 "could not get pin %d for function %s "
@@ -351,7 +362,7 @@ static int acquire_pins(struct pinctrl_dev *pctldev,
                         /* On error release all taken pins */
                         i--; /* this pin just failed */
                         for (; i >= 0; i--)
-                                pin_free(pctldev, pins[i], false);
+                                pin_free(pctldev, pins[i], NULL);
                         return -ENODEV;
                 }
         }
@@ -381,7 +392,7 @@ static void release_pins(struct pinctrl_dev *pctldev,
                 return;
         }
         for (i = 0; i < num_pins; i++)
-                pin_free(pctldev, pins[i], false);
+                pin_free(pctldev, pins[i], NULL);
 }
 
 /**