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pinctrl: add usecount to pins for muxing
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>
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7ecdb16fe6
commit
0e3db173e2
2 changed files with 28 additions and 5 deletions
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@ -82,7 +82,14 @@ 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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* @owner: the device holding this pin or NULL of no device has claimed it
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* @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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*/
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struct pin_desc {
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struct pinctrl_dev *pctldev;
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@ -90,6 +97,7 @@ 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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#endif
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};
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@ -83,11 +83,16 @@ static int pin_request(struct pinctrl_dev *pctldev,
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goto out;
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}
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if (desc->owner && strcmp(desc->owner, owner)) {
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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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}
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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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@ -111,12 +116,18 @@ static int pin_request(struct pinctrl_dev *pctldev,
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else
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status = 0;
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if (status)
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if (status) {
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dev_err(pctldev->dev, "->request on device %s failed for pin %d\n",
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pctldev->desc->name, pin);
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module_put(pctldev->owner);
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}
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out_free_pin:
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if (status)
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desc->owner = NULL;
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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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}
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out:
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if (status)
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dev_err(pctldev->dev, "pin-%d (%s) status %d\n",
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@ -150,6 +161,10 @@ 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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/*
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* If there is no kind of request function for the pin we just assume
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* we got it by default and proceed.
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