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pinctrl: allow concurrent gpio and mux function ownership of pins

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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>
This commit is contained in:
Stephen Warren 2012-03-05 17:22:15 -07:00 committed by Linus Walleij
parent a6c3b33f02
commit 652162d469
2 changed files with 57 additions and 30 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
drivers/pinctrl/core.h
View File

@ -119,15 +119,15 @@ struct pinctrl_setting {
* @name: a name for the pin, e.g. the name of the pin/pad/finger on a
* datasheet or such
* @dynamic_name: if the name of this pin was dynamically allocated
* @usecount: If zero, the pin is not claimed, and @owner should be NULL.
* @mux_usecount: If zero, the pin is not claimed, and @owner should be NULL.
* If non-zero, this pin is claimed by @owner. This field is an integer
* rather than a boolean, since pinctrl_get() might process multiple
* mapping table entries that refer to, and hence claim, the same group
* or pin, and each of these will increment the @usecount.
* @owner: The name of the entity owning the pin. Typically, this is the name
* of the device that called pinctrl_get(). Alternatively, it may be the
* name of the GPIO passed to pinctrl_request_gpio().
* @mux_owner: The name of device that called pinctrl_get().
* @mux_setting: The most recent selected mux setting for this pin, if any.
* @gpio_owner: If pinctrl_request_gpio() was called for this pin, this is
* the name of the GPIO that "owns" this pin.
*/
struct pin_desc {
struct pinctrl_dev *pctldev;
@ -135,9 +135,10 @@ struct pin_desc {
bool dynamic_name;
/* These fields only added when supporting pinmux drivers */
#ifdef CONFIG_PINMUX
unsigned usecount;
const char *owner;
unsigned mux_usecount;
const char *mux_owner;
const struct pinctrl_setting_mux *mux_setting;
const char *gpio_owner;
#endif
};

74
drivers/pinctrl/pinmux.c
View File

@ -94,18 +94,29 @@ static int pin_request(struct pinctrl_dev *pctldev,
goto out;
}
if (desc->usecount && strcmp(desc->owner, owner)) {
dev_err(pctldev->dev,
"pin already requested\n");
goto out;
if (gpio_range) {
/* There's no need to support multiple GPIO requests */
if (desc->gpio_owner) {
dev_err(pctldev->dev,
"pin already requested\n");
goto out;
}
desc->gpio_owner = owner;
} else {
if (desc->mux_usecount && strcmp(desc->mux_owner, owner)) {
dev_err(pctldev->dev,
"pin already requested\n");
goto out;
}
desc->mux_usecount++;
if (desc->mux_usecount > 1)
return 0;
desc->mux_owner = owner;
}
desc->usecount++;
if (desc->usecount > 1)
return 0;
desc->owner = owner;
/* Let each pin increase references to this module */
if (!try_module_get(pctldev->owner)) {
dev_err(pctldev->dev,
@ -135,9 +146,13 @@ static int pin_request(struct pinctrl_dev *pctldev,
out_free_pin:
if (status) {
desc->usecount--;
if (!desc->usecount)
desc->owner = NULL;
if (gpio_range) {
desc->gpio_owner = NULL;
} else {
desc->mux_usecount--;
if (!desc->mux_usecount)
desc->mux_owner = NULL;
}
}
out:
if (status)
@ -172,9 +187,11 @@ static const char *pin_free(struct pinctrl_dev *pctldev, int pin,
return NULL;
}
desc->usecount--;
if (desc->usecount)
return NULL;
if (!gpio_range) {
desc->mux_usecount--;
if (desc->mux_usecount)
return NULL;
}
/*
* If there is no kind of request function for the pin we just assume
@ -185,9 +202,15 @@ static const char *pin_free(struct pinctrl_dev *pctldev, int pin,
else if (ops->free)
ops->free(pctldev, pin);
owner = desc->owner;
desc->owner = NULL;
desc->mux_setting = NULL;
if (gpio_range) {
owner = desc->gpio_owner;
desc->gpio_owner = NULL;
} else {
owner = desc->mux_owner;
desc->mux_owner = NULL;
desc->mux_setting = NULL;
}
module_put(pctldev->owner);
return owner;
@ -493,7 +516,7 @@ static int pinmux_pins_show(struct seq_file *s, void *what)
unsigned i, pin;
seq_puts(s, "Pinmux settings per pin\n");
seq_puts(s, "Format: pin (name): owner\n");
seq_puts(s, "Format: pin (name): mux_owner gpio_owner hog?\n");
mutex_lock(&pinctrl_mutex);
@ -508,13 +531,16 @@ static int pinmux_pins_show(struct seq_file *s, void *what)
if (desc == NULL)
continue;
if (desc->owner &&
!strcmp(desc->owner, pinctrl_dev_get_name(pctldev)))
if (desc->mux_owner &&
!strcmp(desc->mux_owner, pinctrl_dev_get_name(pctldev)))
is_hog = true;
seq_printf(s, "pin %d (%s): %s%s", pin,
seq_printf(s, "pin %d (%s): %s %s%s", pin,
desc->name ? desc->name : "unnamed",
desc->owner ? desc->owner : "UNCLAIMED",
desc->mux_owner ? desc->mux_owner
: "(MUX UNCLAIMED)",
desc->gpio_owner ? desc->gpio_owner
: "(GPIO UNCLAIMED)",
is_hog ? " (HOG)" : "");
if (desc->mux_setting)