pinctrl: allow concurrent gpio and mux function ownership of pins
Per recent updates to Documentation/gpio.txt, gpiolib drivers should inform pinctrl when a GPIO is requested. pinctrl then marks that pin as in-use for that GPIO function. When an SoC muxes pins in a group, it's quite possible for the group to contain e.g. 6 pins, but only 4 of them actually be needed by the HW module that's mux'd to them. In this case, the other 2 pins could be used as GPIOs. However, pinctrl marks all the pins within the group as in-use by the selected mux function. To allow the expected gpiolib interaction, separate the concepts of pin ownership into two parts: One for the mux function and one for GPIO usage. Finally, allow those two ownerships to exist in parallel. Signed-off-by: Stephen Warren <swarren@nvidia.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
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@ -119,15 +119,15 @@ struct pinctrl_setting {
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* @name: a name for the pin, e.g. the name of the pin/pad/finger on a
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* datasheet or such
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* @dynamic_name: if the name of this pin was dynamically allocated
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* @usecount: If zero, the pin is not claimed, and @owner should be NULL.
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* @mux_usecount: If zero, the pin is not claimed, and @owner should be NULL.
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* If non-zero, this pin is claimed by @owner. This field is an integer
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* rather than a boolean, since pinctrl_get() might process multiple
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* mapping table entries that refer to, and hence claim, the same group
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* or pin, and each of these will increment the @usecount.
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* @owner: The name of the entity owning the pin. Typically, this is the name
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* of the device that called pinctrl_get(). Alternatively, it may be the
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* name of the GPIO passed to pinctrl_request_gpio().
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* @mux_owner: The name of device that called pinctrl_get().
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* @mux_setting: The most recent selected mux setting for this pin, if any.
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* @gpio_owner: If pinctrl_request_gpio() was called for this pin, this is
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* the name of the GPIO that "owns" this pin.
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*/
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struct pin_desc {
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struct pinctrl_dev *pctldev;
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@ -135,9 +135,10 @@ struct pin_desc {
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bool dynamic_name;
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/* These fields only added when supporting pinmux drivers */
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#ifdef CONFIG_PINMUX
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unsigned usecount;
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const char *owner;
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unsigned mux_usecount;
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const char *mux_owner;
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const struct pinctrl_setting_mux *mux_setting;
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const char *gpio_owner;
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#endif
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};
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@ -94,18 +94,29 @@ static int pin_request(struct pinctrl_dev *pctldev,
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goto out;
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}
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if (desc->usecount && strcmp(desc->owner, owner)) {
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dev_err(pctldev->dev,
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"pin already requested\n");
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goto out;
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if (gpio_range) {
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/* There's no need to support multiple GPIO requests */
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if (desc->gpio_owner) {
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dev_err(pctldev->dev,
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"pin already requested\n");
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goto out;
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}
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desc->gpio_owner = owner;
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} else {
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if (desc->mux_usecount && strcmp(desc->mux_owner, owner)) {
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dev_err(pctldev->dev,
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"pin already requested\n");
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goto out;
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}
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desc->mux_usecount++;
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if (desc->mux_usecount > 1)
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return 0;
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desc->mux_owner = owner;
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}
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desc->usecount++;
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if (desc->usecount > 1)
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return 0;
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desc->owner = owner;
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/* Let each pin increase references to this module */
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if (!try_module_get(pctldev->owner)) {
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dev_err(pctldev->dev,
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@ -135,9 +146,13 @@ static int pin_request(struct pinctrl_dev *pctldev,
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out_free_pin:
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if (status) {
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desc->usecount--;
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if (!desc->usecount)
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desc->owner = NULL;
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if (gpio_range) {
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desc->gpio_owner = NULL;
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} else {
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desc->mux_usecount--;
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if (!desc->mux_usecount)
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desc->mux_owner = NULL;
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}
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}
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out:
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if (status)
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@ -172,9 +187,11 @@ static const char *pin_free(struct pinctrl_dev *pctldev, int pin,
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return NULL;
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}
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desc->usecount--;
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if (desc->usecount)
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return NULL;
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if (!gpio_range) {
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desc->mux_usecount--;
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if (desc->mux_usecount)
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return NULL;
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}
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/*
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* If there is no kind of request function for the pin we just assume
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@ -185,9 +202,15 @@ static const char *pin_free(struct pinctrl_dev *pctldev, int pin,
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else if (ops->free)
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ops->free(pctldev, pin);
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owner = desc->owner;
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desc->owner = NULL;
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desc->mux_setting = NULL;
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if (gpio_range) {
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owner = desc->gpio_owner;
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desc->gpio_owner = NULL;
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} else {
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owner = desc->mux_owner;
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desc->mux_owner = NULL;
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desc->mux_setting = NULL;
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}
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module_put(pctldev->owner);
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return owner;
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@ -493,7 +516,7 @@ static int pinmux_pins_show(struct seq_file *s, void *what)
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unsigned i, pin;
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seq_puts(s, "Pinmux settings per pin\n");
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seq_puts(s, "Format: pin (name): owner\n");
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seq_puts(s, "Format: pin (name): mux_owner gpio_owner hog?\n");
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mutex_lock(&pinctrl_mutex);
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@ -508,13 +531,16 @@ static int pinmux_pins_show(struct seq_file *s, void *what)
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if (desc == NULL)
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continue;
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if (desc->owner &&
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!strcmp(desc->owner, pinctrl_dev_get_name(pctldev)))
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if (desc->mux_owner &&
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!strcmp(desc->mux_owner, pinctrl_dev_get_name(pctldev)))
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is_hog = true;
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seq_printf(s, "pin %d (%s): %s%s", pin,
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seq_printf(s, "pin %d (%s): %s %s%s", pin,
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desc->name ? desc->name : "unnamed",
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desc->owner ? desc->owner : "UNCLAIMED",
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desc->mux_owner ? desc->mux_owner
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: "(MUX UNCLAIMED)",
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desc->gpio_owner ? desc->gpio_owner
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: "(GPIO UNCLAIMED)",
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is_hog ? " (HOG)" : "");
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if (desc->mux_setting)
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