twl4030-gpio supports LED signals

Expose the two TWL4030 LED signals as output-only GPIOs.  Boards
need to explicitly ask that this be done, to help avoid conflicts
on boards using these same pins to hook up to a vibrator motor.

Note that these are high drive open drain signals; LEDA is rated
for up to 160 mA (!), LEDB up to 60 mA.  Boards using one of these
signals to drive a bank of LCD backlight LEDs would probably want
to access the dedicated PWMs for brightness control, too; easy to
add such support later.

Example:  Beagle has one real LED here (PWM not necessary), and
one GPIO controlling VBUS output over EHCI (PWM not wanted).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Tony Lindgren <tony@atomide.com>

diff --git a/drivers/gpio/twl4030-gpio.c b/drivers/gpio/twl4030-gpio.c
index 4c16429..e497436 100644 (file)
--- a/drivers/gpio/twl4030-gpio.c
+++ b/drivers/gpio/twl4030-gpio.c
@@ -85,6 +85,32 @@ static inline int gpio_twl4030_write(u8 address, u8 data)
        return twl4030_i2c_write_u8(TWL4030_MODULE_GPIO, data, address);
 }
 
+/*----------------------------------------------------------------------*/
+
+/*
+ * LED register offsets (use TWL4030_MODULE_{LED,PWMA,PWMB}))
+ * PWMs A and B are dedicated to LEDs A and B, respectively.
+ */
+
+#define TWL4030_LED_LEDEN      0x0
+
+/* LEDEN bits */
+#define LEDEN_LEDAON           BIT(0)
+#define LEDEN_LEDBON           BIT(1)
+#define LEDEN_LEDAEXT          BIT(2)
+#define LEDEN_LEDBEXT          BIT(3)
+#define LEDEN_LEDAPWM          BIT(4)
+#define LEDEN_LEDBPWM          BIT(5)
+#define LEDEN_PWM_LENGTHA      BIT(6)
+#define LEDEN_PWM_LENGTHB      BIT(7)
+
+#define TWL4030_PWMx_PWMxON    0x0
+#define TWL4030_PWMx_PWMxOFF   0x1
+
+#define PWMxON_LENGTH          BIT(7)
+
+/*----------------------------------------------------------------------*/
+
 /*
  * To read a TWL4030 GPIO module register
  */
@@ -97,6 +123,32 @@ static inline int gpio_twl4030_read(u8 address)
        return (ret < 0) ? ret : data;
 }
 
+/*----------------------------------------------------------------------*/
+
+static u8 cached_leden;                /* protected by gpio_lock */
+
+/* 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
+ * as a LED brightness control; we initialize it as "always on".
+ */
+static void twl4030_led_set_value(int led, int value)
+{
+       u8 mask = LEDEN_LEDAON | LEDEN_LEDAPWM;
+       int status;
+
+       if (led)
+               mask <<= 1;
+
+       mutex_lock(&gpio_lock);
+       if (value)
+               cached_leden &= ~mask;
+       else
+               cached_leden |= mask;
+       status = twl4030_i2c_write_u8(TWL4030_MODULE_LED, cached_leden,
+                       TWL4030_LED_LEDEN);
+       mutex_unlock(&gpio_lock);
+}
+
 static int twl4030_set_gpio_direction(int gpio, int is_input)
 {
        u8 d_bnk = gpio >> 3;
@@ -226,6 +278,44 @@ static int twl_request(struct gpio_chip *chip, unsigned offset)
 
        mutex_lock(&gpio_lock);
 
+       /* Support the two LED outputs as output-only GPIOs. */
+       if (offset >= TWL4030_GPIO_MAX) {
+               u8      ledclr_mask = LEDEN_LEDAON | LEDEN_LEDAEXT
+                               | LEDEN_LEDAPWM | LEDEN_PWM_LENGTHA;
+               u8      module = TWL4030_MODULE_PWMA;
+
+               offset -= TWL4030_GPIO_MAX;
+               if (offset) {
+                       ledclr_mask <<= 1;
+                       module = TWL4030_MODULE_PWMB;
+               }
+
+               /* initialize PWM to always-drive */
+               status = twl4030_i2c_write_u8(module, 0x7f,
+                               TWL4030_PWMx_PWMxOFF);
+               if (status < 0)
+                       goto done;
+               status = twl4030_i2c_write_u8(module, 0x7f,
+                               TWL4030_PWMx_PWMxON);
+               if (status < 0)
+                       goto done;
+
+               /* init LED to not-driven (high) */
+               module = TWL4030_MODULE_LED;
+               status = twl4030_i2c_read_u8(module, &cached_leden,
+                               TWL4030_LED_LEDEN);
+               if (status < 0)
+                       goto done;
+               cached_leden &= ~ledclr_mask;
+               status = twl4030_i2c_write_u8(module, cached_leden,
+                               TWL4030_LED_LEDEN);
+               if (status < 0)
+                       goto done;
+
+               status = 0;
+               goto done;
+       }
+
        /* on first use, turn GPIO module "on" */
        if (!gpio_usage_count)
                status = gpio_twl4030_write(REG_GPIO_CTRL,
@@ -241,6 +331,11 @@ done:
 
 static void twl_free(struct gpio_chip *chip, unsigned offset)
 {
+       if (offset >= TWL4030_GPIO_MAX) {
+               twl4030_led_set_value(offset - TWL4030_GPIO_MAX, 1);
+               return;
+       }
+
        mutex_lock(&gpio_lock);
 
        gpio_usage_count &= ~BIT(offset);
@@ -254,30 +349,46 @@ static void twl_free(struct gpio_chip *chip, unsigned offset)
 
 static int twl_direction_in(struct gpio_chip *chip, unsigned offset)
 {
-       return twl4030_set_gpio_direction(offset, 1);
+       return (offset < TWL4030_GPIO_MAX)
+               ? twl4030_set_gpio_direction(offset, 1)
+               : -EINVAL;
 }
 
 static int twl_get(struct gpio_chip *chip, unsigned offset)
 {
-       int status = twl4030_get_gpio_datain(offset);
+       int status = 0;
 
+       if (offset < TWL4030_GPIO_MAX)
+               status = twl4030_get_gpio_datain(offset);
+       else if (offset == TWL4030_GPIO_MAX)
+               status = cached_leden & LEDEN_LEDAON;
+       else
+               status = cached_leden & LEDEN_LEDBON;
        return (status < 0) ? 0 : status;
 }
 
 static int twl_direction_out(struct gpio_chip *chip, unsigned offset, int value)
 {
-       twl4030_set_gpio_dataout(offset, value);
-       return twl4030_set_gpio_direction(offset, 0);
+       if (offset < TWL4030_GPIO_MAX) {
+               twl4030_set_gpio_dataout(offset, value);
+               return twl4030_set_gpio_direction(offset, 0);
+       } else {
+               twl4030_led_set_value(offset - TWL4030_GPIO_MAX, value);
+               return 0;
+       }
 }
 
 static void twl_set(struct gpio_chip *chip, unsigned offset, int value)
 {
-       twl4030_set_gpio_dataout(offset, value);
+       if (offset < TWL4030_GPIO_MAX)
+               twl4030_set_gpio_dataout(offset, value);
+       else
+               twl4030_led_set_value(offset - TWL4030_GPIO_MAX, value);
 }
 
 static int twl_to_irq(struct gpio_chip *chip, unsigned offset)
 {
-       return twl4030_gpio_irq_base
+       return (twl4030_gpio_irq_base && (offset < TWL4030_GPIO_MAX))
                ? (twl4030_gpio_irq_base + offset)
                : -EINVAL;
 }
@@ -360,6 +471,12 @@ no_irqs:
        twl_gpiochip.ngpio = TWL4030_GPIO_MAX;
        twl_gpiochip.dev = &pdev->dev;
 
+       /* NOTE: we assume VIBRA_CTL.VIBRA_EN, in MODULE_AUDIO_VOICE,
+        * is (still) clear if use_leds is set.
+        */
+       if (pdata->use_leds)
+               twl_gpiochip.ngpio += 2;
+
        ret = gpiochip_add(&twl_gpiochip);
        if (ret < 0) {
                dev_err(&pdev->dev,

diff --git a/include/linux/i2c/twl4030.h b/include/linux/i2c/twl4030.h
index aab2ee6..03b9482 100644 (file)
--- a/include/linux/i2c/twl4030.h
+++ b/include/linux/i2c/twl4030.h
@@ -228,6 +228,9 @@ struct twl4030_gpio_platform_data {
        int             gpio_base;
        unsigned        irq_base, irq_end;
 
+       /* package the two LED signals as output-only GPIOs? */
+       bool            use_leds;
+
        /* For gpio-N, bit (1 << N) in "pullups" is set if that pullup
         * should be enabled.  Else, if that bit is set in "pulldowns",
         * that pulldown is enabled.  Don't waste power by letting any