Use more coherent locking in the driver. Use bitfield to store the GPIO
direction and if the pin is configured as output store the status also in a
bitfiled.
In this way we can just look at these bitfields when we need information
about the pin status and only reach out to the chip when it is needed.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx>
Acked-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
---
Hi Grant,
Changes sicne v2:
- Fixed the mutex_unlock found by Michael.
- Removed the debug prints addedd by v2 patch (remains from debugging)
- Removed one blank line between includes and the first comment section.
Regards,
Peter
drivers/gpio/gpio-twl4030.c | 100 ++++++++++++++++++++++++++++----------------
1 file changed, 65 insertions(+), 35 deletions(-)
diff --git a/drivers/gpio/gpio-twl4030.c b/drivers/gpio/gpio-twl4030.c
index 4643f9c..4d330e3 100644
--- a/drivers/gpio/gpio-twl4030.c
+++ b/drivers/gpio/gpio-twl4030.c
@@ -37,7 +37,6 @@
#include <linux/i2c/twl.h>
-
/*
* The GPIO "subchip" supports 18 GPIOs which can be configured as
* inputs or outputs, with pullups or pulldowns on each pin. Each
@@ -64,14 +63,15 @@
/* Mask for GPIO registers when aggregated into a 32-bit integer */
#define GPIO_32_MASK 0x0003ffff
-/* Data structures */
-static DEFINE_MUTEX(gpio_lock);
-
struct gpio_twl4030_priv {
struct gpio_chip gpio_chip;
+ struct mutex mutex;
int irq_base;
+ /* Bitfields for state caching */
unsigned int usage_count;
+ unsigned int direction;
+ unsigned int out_state;
};
/*----------------------------------------------------------------------*/
@@ -130,7 +130,7 @@ static inline int gpio_twl4030_read(u8 address)
/*----------------------------------------------------------------------*/
-static u8 cached_leden; /* protected by gpio_lock */
+static u8 cached_leden;
/* The LED lines are open drain outputs ... a FET pulls to GND, so an
* external pullup is needed. We could also expose the integrated PWM
@@ -144,14 +144,12 @@ static void twl4030_led_set_value(int led, int value)
if (led)
mask <<= 1;
- mutex_lock(&gpio_lock);
if (value)
cached_leden &= ~mask;
else
cached_leden |= mask;
status = twl_i2c_write_u8(TWL4030_MODULE_LED, cached_leden,
TWL4030_LED_LEDEN_REG);
- mutex_unlock(&gpio_lock);
}
static int twl4030_set_gpio_direction(int gpio, int is_input)
@@ -162,7 +160,6 @@ static int twl4030_set_gpio_direction(int gpio, int is_input)
u8 base = REG_GPIODATADIR1 + d_bnk;
int ret = 0;
- mutex_lock(&gpio_lock);
ret = gpio_twl4030_read(base);
if (ret >= 0) {
if (is_input)
@@ -172,7 +169,6 @@ static int twl4030_set_gpio_direction(int gpio, int is_input)
ret = gpio_twl4030_write(base, reg);
}
- mutex_unlock(&gpio_lock);
return ret;
}
@@ -212,7 +208,7 @@ static int twl_request(struct gpio_chip *chip, unsigned offset)
struct gpio_twl4030_priv *priv = to_gpio_twl4030(chip);
int status = 0;
- mutex_lock(&gpio_lock);
+ mutex_lock(&priv->mutex);
/* Support the two LED outputs as output-only GPIOs. */
if (offset >= TWL4030_GPIO_MAX) {
@@ -271,7 +267,7 @@ done:
if (!status)
priv->usage_count |= BIT(offset);
- mutex_unlock(&gpio_lock);
+ mutex_unlock(&priv->mutex);
return status;
}
@@ -279,64 +275,96 @@ static void twl_free(struct gpio_chip *chip, unsigned offset)
{
struct gpio_twl4030_priv *priv = to_gpio_twl4030(chip);
+ mutex_lock(&priv->mutex);
if (offset >= TWL4030_GPIO_MAX) {
twl4030_led_set_value(offset - TWL4030_GPIO_MAX, 1);
- return;
+ goto out;
}
- mutex_lock(&gpio_lock);
-
priv->usage_count &= ~BIT(offset);
/* on last use, switch off GPIO module */
if (!priv->usage_count)
gpio_twl4030_write(REG_GPIO_CTRL, 0x0);
- mutex_unlock(&gpio_lock);
+out:
+ mutex_unlock(&priv->mutex);
}
static int twl_direction_in(struct gpio_chip *chip, unsigned offset)
{
- return (offset < TWL4030_GPIO_MAX)
- ? twl4030_set_gpio_direction(offset, 1)
- : -EINVAL;
+ struct gpio_twl4030_priv *priv = to_gpio_twl4030(chip);
+ int ret;
+
+ mutex_lock(&priv->mutex);
+ if (offset < TWL4030_GPIO_MAX)
+ ret = twl4030_set_gpio_direction(offset, 1);
+ else
+ ret = -EINVAL;
+
+ if (!ret)
+ priv->direction &= ~BIT(offset);
+
+ mutex_unlock(&priv->mutex);
+
+ return ret;
}
static int twl_get(struct gpio_chip *chip, unsigned offset)
{
struct gpio_twl4030_priv *priv = to_gpio_twl4030(chip);
+ int ret;
int status = 0;
- if (!(priv->usage_count & BIT(offset)))
- return -EPERM;
+ mutex_lock(&priv->mutex);
+ if (!(priv->usage_count & BIT(offset))) {
+ ret = -EPERM;
+ goto out;
+ }
- if (offset < TWL4030_GPIO_MAX)
- status = twl4030_get_gpio_datain(offset);
- else if (offset == TWL4030_GPIO_MAX)
- status = cached_leden & LEDEN_LEDAON;
+ if (priv->direction & BIT(offset))
+ status = priv->out_state & BIT(offset);
else
- status = cached_leden & LEDEN_LEDBON;
+ status = twl4030_get_gpio_datain(offset);
- return (status < 0) ? 0 : status;
+ ret = (status <= 0) ? 0 : 1;
+out:
+ mutex_unlock(&priv->mutex);
+ return ret;
}
-static int twl_direction_out(struct gpio_chip *chip, unsigned offset, int value)
+static void twl_set(struct gpio_chip *chip, unsigned offset, int value)
{
- if (offset < TWL4030_GPIO_MAX) {
+ struct gpio_twl4030_priv *priv = to_gpio_twl4030(chip);
+
+ mutex_lock(&priv->mutex);
+ if (offset < TWL4030_GPIO_MAX)
twl4030_set_gpio_dataout(offset, value);
- return twl4030_set_gpio_direction(offset, 0);
- } else {
+ else
twl4030_led_set_value(offset - TWL4030_GPIO_MAX, value);
- return 0;
- }
+
+ if (value)
+ priv->out_state |= BIT(offset);
+ else
+ priv->out_state &= ~BIT(offset);
+
+ mutex_unlock(&priv->mutex);
}
-static void twl_set(struct gpio_chip *chip, unsigned offset, int value)
+static int twl_direction_out(struct gpio_chip *chip, unsigned offset, int value)
{
+ struct gpio_twl4030_priv *priv = to_gpio_twl4030(chip);
+
+ mutex_lock(&priv->mutex);
if (offset < TWL4030_GPIO_MAX)
twl4030_set_gpio_dataout(offset, value);
- else
- twl4030_led_set_value(offset - TWL4030_GPIO_MAX, value);
+
+ priv->direction |= BIT(offset);
+ mutex_unlock(&priv->mutex);
+
+ twl_set(chip, offset, value);
+
+ return 0;
}
static int twl_to_irq(struct gpio_chip *chip, unsigned offset)
@@ -469,6 +497,8 @@ no_irqs:
priv->gpio_chip.ngpio = TWL4030_GPIO_MAX;
priv->gpio_chip.dev = &pdev->dev;
+ mutex_init(&priv->mutex);
+
if (node)
pdata = of_gpio_twl4030(&pdev->dev);
--
1.8.0.2
--
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