leds: pca9633: Add hardware blink support

Add hardware blinking support to the pca9633 driver.

NOTE: Hardware blinking violates the leds infrastructure
driver interface since the hardware only supports
blinking all LEDs with the same delay_on/delay_off
rates.  That is, only the LEDs that are set to blink
will actually blink but all LEDs that are set to blink
will blink in identical fashion.  The delay_on/delay_off
values of the last LED that is set to blink will be used
for all of the blinking LEDs.  If the hardware doesn't
support the requested blinking pattern, a default of
500ms on and off will be used.

Hardware blinking is disabled by default but can be enabled
by setting the 'blink_type' member in the platform_data
struct to 'PCA9633_HW_BLINK' or by adding the 'nxp,hw-blink'
property to the DTS.

(fengguang.wu@intel.com: Removes unneeded semicolon.)

Signed-off-by: Mark A. Greer <mgreer@animalcreek.com>
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

3 files changed, 139 insertions, 4 deletions

diff --git a/Documentation/devicetree/bindings/leds/pca9633.txt b/Documentation/devicetree/bindings/leds/pca9633.txt
index 8140512c0ac8..6d9e1a9e7e9f 100644
--- a/Documentation/devicetree/bindings/leds/pca9633.txt
+++ b/Documentation/devicetree/bindings/leds/pca9633.txt
@@ -5,6 +5,7 @@ Required properties:
 
 Optional properties:
 - nxp,totem-pole : use totem pole (push-pull) instead of default open-drain
+- nxp,hw-blink : use hardware blinking instead of software blinking
 
 Each led is represented as a sub-node of the nxp,pca9633 device.
 
diff --git a/drivers/leds/leds-pca9633.c b/drivers/leds/leds-pca9633.c
index 90935e465c4d..77b3f24b7207 100644
--- a/drivers/leds/leds-pca9633.c
+++ b/drivers/leds/leds-pca9633.c
@@ -11,6 +11,15 @@
  *
  * LED driver for the PCA9633 I2C LED driver (7-bit slave address 0x62)
  *
+ * Note that hardware blinking violates the leds infrastructure driver
+ * interface since the hardware only supports blinking all LEDs with the
+ * same delay_on/delay_off rates.  That is, only the LEDs that are set to
+ * blink will actually blink but all LEDs that are set to blink will blink
+ * in identical fashion.  The delay_on/delay_off values of the last LED
+ * that is set to blink will be used for all of the blinking LEDs.
+ * Hardware blinking is disabled by default but can be enabled by setting
+ * the 'blink_type' member in the platform_data struct to 'PCA9633_HW_BLINK'
+ * or by adding the 'nxp,hw-blink' property to the DTS.
  */
 
 #include <linux/module.h>
@@ -31,30 +40,44 @@
 #define PCA9633_LED_PWM         0x2     /* Controlled through PWM */
 #define PCA9633_LED_GRP_PWM     0x3     /* Controlled through PWM/GRPPWM */
 
+#define PCA9633_MODE2_DMBLNK    0x20    /* Enable blinking */
+
 #define PCA9633_MODE1           0x00
 #define PCA9633_MODE2           0x01
 #define PCA9633_PWM_BASE        0x02
+#define PCA9633_GRPPWM          0x06
+#define PCA9633_GRPFREQ         0x07
 #define PCA9633_LEDOUT          0x08
 
+/* Total blink period in milliseconds */
+#define PCA9632_BLINK_PERIOD_MIN        42
+#define PCA9632_BLINK_PERIOD_MAX        10667
+
 static const struct i2c_device_id pca9633_id[] = {
         { "pca9633", 0 },
         { }
 };
 MODULE_DEVICE_TABLE(i2c, pca9633_id);
 
+enum pca9633_cmd {
+        BRIGHTNESS_SET,
+        BLINK_SET,
+};
+
 struct pca9633_led {
         struct i2c_client *client;
         struct work_struct work;
         enum led_brightness brightness;
         struct led_classdev led_cdev;
         int led_num; /* 0 .. 3 potentially */
+        enum pca9633_cmd cmd;
         char name[32];
+        u8 gdc;
+        u8 gfrq;
 };
 
-static void pca9633_led_work(struct work_struct *work)
+static void pca9633_brightness_work(struct pca9633_led *pca9633)
 {
-        struct pca9633_led *pca9633 = container_of(work,
-                struct pca9633_led, work);
         u8 ledout = i2c_smbus_read_byte_data(pca9633->client, PCA9633_LEDOUT);
         int shift = 2 * pca9633->led_num;
         u8 mask = 0x3 << shift;
@@ -78,6 +101,43 @@ static void pca9633_led_work(struct work_struct *work)
         }
 }
 
+static void pca9633_blink_work(struct pca9633_led *pca9633)
+{
+        u8 ledout = i2c_smbus_read_byte_data(pca9633->client, PCA9633_LEDOUT);
+        u8 mode2 = i2c_smbus_read_byte_data(pca9633->client, PCA9633_MODE2);
+        int shift = 2 * pca9633->led_num;
+        u8 mask = 0x3 << shift;
+
+        i2c_smbus_write_byte_data(pca9633->client, PCA9633_GRPPWM,
+                pca9633->gdc);
+
+        i2c_smbus_write_byte_data(pca9633->client, PCA9633_GRPFREQ,
+                pca9633->gfrq);
+
+        if (!(mode2 & PCA9633_MODE2_DMBLNK))
+                i2c_smbus_write_byte_data(pca9633->client, PCA9633_MODE2,
+                        mode2 | PCA9633_MODE2_DMBLNK);
+
+        if ((ledout & mask) != (PCA9633_LED_GRP_PWM << shift))
+                i2c_smbus_write_byte_data(pca9633->client, PCA9633_LEDOUT,
+                        (ledout & ~mask) | (PCA9633_LED_GRP_PWM << shift));
+}
+
+static void pca9633_work(struct work_struct *work)
+{
+        struct pca9633_led *pca9633 = container_of(work,
+                struct pca9633_led, work);
+
+        switch (pca9633->cmd) {
+        case BRIGHTNESS_SET:
+                pca9633_brightness_work(pca9633);
+                break;
+        case BLINK_SET:
+                pca9633_blink_work(pca9633);
+                break;
+        }
+}
+
 static void pca9633_led_set(struct led_classdev *led_cdev,
         enum led_brightness value)
 {
@@ -85,6 +145,7 @@ static void pca9633_led_set(struct led_classdev *led_cdev,
 
         pca9633 = container_of(led_cdev, struct pca9633_led, led_cdev);
 
+        pca9633->cmd = BRIGHTNESS_SET;
         pca9633->brightness = value;
 
         /*
@@ -94,6 +155,64 @@ static void pca9633_led_set(struct led_classdev *led_cdev,
         schedule_work(&pca9633->work);
 }
 
+static int pca9633_blink_set(struct led_classdev *led_cdev,
+                unsigned long *delay_on, unsigned long *delay_off)
+{
+        struct pca9633_led *pca9633;
+        unsigned long time_on, time_off, period;
+        u8 gdc, gfrq;
+
+        pca9633 = container_of(led_cdev, struct pca9633_led, led_cdev);
+
+        time_on = *delay_on;
+        time_off = *delay_off;
+
+        /* If both zero, pick reasonable defaults of 500ms each */
+        if (!time_on && !time_off) {
+                time_on = 500;
+                time_off = 500;
+        }
+
+        period = time_on + time_off;
+
+        /* If period not supported by hardware, default to someting sane. */
+        if ((period < PCA9632_BLINK_PERIOD_MIN) ||
+            (period > PCA9632_BLINK_PERIOD_MAX)) {
+                time_on = 500;
+                time_off = 500;
+                period = time_on + time_off;
+        }
+
+        /*
+         * From manual: duty cycle = (GDC / 256) ->
+         *      (time_on / period) = (GDC / 256) ->
+         *              GDC = ((time_on * 256) / period)
+         */
+        gdc = (time_on * 256) / period;
+
+        /*
+         * From manual: period = ((GFRQ + 1) / 24) in seconds.
+         * So, period (in ms) = (((GFRQ + 1) / 24) * 1000) ->
+         *              GFRQ = ((period * 24 / 1000) - 1)
+         */
+        gfrq = (period * 24 / 1000) - 1;
+
+        pca9633->cmd = BLINK_SET;
+        pca9633->gdc = gdc;
+        pca9633->gfrq = gfrq;
+
+        /*
+         * Must use workqueue for the actual I/O since I2C operations
+         * can sleep.
+         */
+        schedule_work(&pca9633->work);
+
+        *delay_on = time_on;
+        *delay_off = time_off;
+
+        return 0;
+}
+
 #if IS_ENABLED(CONFIG_OF)
 static struct pca9633_platform_data *
 pca9633_dt_init(struct i2c_client *client)
@@ -140,6 +259,12 @@ pca9633_dt_init(struct i2c_client *client)
         else
                 pdata->outdrv = PCA9633_OPEN_DRAIN;
 
+        /* default to software blinking unless hardware blinking is specified */
+        if (of_property_read_bool(np, "nxp,hw-blink"))
+                pdata->blink_type = PCA9633_HW_BLINK;
+        else
+                pdata->blink_type = PCA9633_SW_BLINK;
+
         return pdata;
 }
 
@@ -206,7 +331,10 @@ static int pca9633_probe(struct i2c_client *client,
                 pca9633[i].led_cdev.name = pca9633[i].name;
                 pca9633[i].led_cdev.brightness_set = pca9633_led_set;
 
-                INIT_WORK(&pca9633[i].work, pca9633_led_work);
+                if (pdata && pdata->blink_type == PCA9633_HW_BLINK)
+                        pca9633[i].led_cdev.blink_set = pca9633_blink_set;
+
+                INIT_WORK(&pca9633[i].work, pca9633_work);
 
                 err = led_classdev_register(&client->dev, &pca9633[i].led_cdev);
                 if (err < 0)
diff --git a/include/linux/platform_data/leds-pca9633.h b/include/linux/platform_data/leds-pca9633.h
index c5bf29b6fa7f..3c1037a81d34 100644
--- a/include/linux/platform_data/leds-pca9633.h
+++ b/include/linux/platform_data/leds-pca9633.h
@@ -27,9 +27,15 @@ enum pca9633_outdrv {
         PCA9633_TOTEM_POLE, /* aka push-pull */
 };
 
+enum pca9633_blink_type {
+        PCA9633_SW_BLINK,
+        PCA9633_HW_BLINK,
+};
+
 struct pca9633_platform_data {
         struct led_platform_data leds;
         enum pca9633_outdrv outdrv;
+        enum pca9633_blink_type blink_type;
 };
 
 #endif /* __LINUX_PCA9633_H*/