lkml.org 
[lkml]   [2012]   [Feb]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 17/20] pinctrl: Add usecount to pins for muxing
Date
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>
---
drivers/pinctrl/core.h | 1 +
drivers/pinctrl/pinmux.c | 29 ++++++++++++++++++++++-------
2 files changed, 23 insertions(+), 7 deletions(-)
diff --git a/drivers/pinctrl/core.h b/drivers/pinctrl/core.h
index 1290995..64ae1b8 100644
--- a/drivers/pinctrl/core.h
+++ b/drivers/pinctrl/core.h
@@ -92,6 +92,7 @@ struct pin_desc {
bool dynamic_name;
/* These fields only added when supporting pinmux drivers */
#ifdef CONFIG_PINMUX
+ unsigned usecount;
const char *owner;
#endif
};
diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
index 8d32380..359f6ac 100644
--- a/drivers/pinctrl/pinmux.c
+++ b/drivers/pinctrl/pinmux.c
@@ -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 */
@@ -100,9 +105,9 @@ 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 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_request_enable)
/* This requests and enables a single GPIO pin */
status = ops->gpio_request_enable(pctldev, gpio_range, pin);
@@ -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.
--
1.7.5.4


\
 
 \ /
  Last update: 2012-02-20 07:51    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site