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Date: Wed, 19 Dec 2012 21:53:23 +0100
From: Michael Trimarchi <michael@...rulasolutions.com>
To: Grant Likely <grant.likely@...retlab.ca>,
Peter Ujfalusi <peter.ujfalusi@...com>,
Linus Walleij <linus.walleij@...aro.org>
CC: linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org
Subject: Re: [PATCH v2 2/3] gpio: twl4030: Cache the direction and output states in private data
Hi
Grant Likely <grant.likely@...retlab.ca> wrote:
>On Thu, 6 Dec 2012 11:52:06 +0100, Peter Ujfalusi
><peter.ujfalusi@...com> wrote:
>> 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@...com>
>
>Applied, thanks
>
>g.
>
>> ---
>> drivers/gpio/gpio-twl4030.c | 99
>++++++++++++++++++++++++++++++---------------
>> 1 file changed, 66 insertions(+), 33 deletions(-)
>>
>> diff --git a/drivers/gpio/gpio-twl4030.c
>b/drivers/gpio/gpio-twl4030.c
>> index c092739..a38e6e9c 100644
>> --- a/drivers/gpio/gpio-twl4030.c
>> +++ b/drivers/gpio/gpio-twl4030.c
>> @@ -64,14 +64,15 @@
>> /* 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 +131,7 @@ 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 +145,12 @@ 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 +161,6 @@ 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 +170,6 @@ 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 +209,7 @@ 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 +268,7 @@ done:
>> if (!status)
>> priv->usage_count |= BIT(offset);
>>
>> - mutex_unlock(&gpio_lock);
>> + mutex_unlock(&priv->mutex);
>> return status;
>> }
>>
>> @@ -279,64 +276,98 @@ 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);
I have the mobile but where is the unlock here?
>> return;
>> }
>>
>> - 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);
>> + 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);
>> + dev_err(chip->dev, "%s: offset %d value %d\n", __func__, offset,
>ret);
>> + 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);
>> +
>> + dev_err(chip->dev, "%s: offset %d value %d\n", __func__, offset,
>value);
>> + 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);
>> +
>> + dev_err(chip->dev, "%s: offset %d value %d\n", __func__, offset,
>value);
>> + 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 +500,8 @@ 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
>>
--
Sent from my Android phone with K-9 Mail. Please excuse my brevity.
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