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pinctrl: add usecount to pins for muxing

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Multiple mapping table entries could reference the same pin, and hence
"own" it. This would be unusual now that pinctrl_get() represents a single
state for a client device, but in the future when it represents all known
states for a device, this is quite likely. Implement reference counting
for pin ownership to handle this.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Dong Aisheng <dong.aisheng@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Stephen Warren 2012-03-02 13:05:46 -07:00 committed by Linus Walleij
parent 7ecdb16fe6
commit 0e3db173e2
2 changed files with 28 additions and 5 deletions
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10
drivers/pinctrl/core.h
View File

@ -82,7 +82,14 @@ 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
* @owner: the device holding this pin or NULL of no device has claimed it
* @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().
*/
struct pin_desc {
struct pinctrl_dev *pctldev;
@ -90,6 +97,7 @@ struct pin_desc {
bool dynamic_name;
/* These fields only added when supporting pinmux drivers */
#ifdef CONFIG_PINMUX
unsigned usecount;
const char *owner;
#endif
};

23
drivers/pinctrl/pinmux.c
View File

@ -83,11 +83,16 @@ static int pin_request(struct pinctrl_dev *pctldev,
goto out;
}
if (desc->owner && strcmp(desc->owner, owner)) {
if (desc->usecount && strcmp(desc->owner, owner)) {
dev_err(pctldev->dev,
"pin already requested\n");
goto out;
}
desc->usecount++;
if (desc->usecount > 1)
return 0;
desc->owner = owner;
/* Let each pin increase references to this module */
@ -111,12 +116,18 @@ static int pin_request(struct pinctrl_dev *pctldev,
else
status = 0;
if (status)
if (status) {
dev_err(pctldev->dev, "->request on device %s failed for pin %d\n",
pctldev->desc->name, pin);
module_put(pctldev->owner);
}
out_free_pin:
if (status)
desc->owner = NULL;
if (status) {
desc->usecount--;
if (!desc->usecount)
desc->owner = NULL;
}
out:
if (status)
dev_err(pctldev->dev, "pin-%d (%s) status %d\n",
@ -150,6 +161,10 @@ static const char *pin_free(struct pinctrl_dev *pctldev, int pin,
return NULL;
}
desc->usecount--;
if (desc->usecount)
return NULL;
/*
* If there is no kind of request function for the pin we just assume
* we got it by default and proceed.