leds: pca955x: Implement the default-state property

In order to retain the LED state after a system reboot, check the
documented default-state device tree property during initialization.
Modify the behavior of the probe according to the property.

Signed-off-by: Eddie James <eajames@linux.ibm.com>
Signed-off-by: Pavel Machek <pavel@ucw.cz>

diff --git a/drivers/leds/leds-pca955x.c b/drivers/leds/leds-pca955x.c
index e47ba7c..fa1d77d 100644 (file)
--- a/drivers/leds/leds-pca955x.c
+++ b/drivers/leds/leds-pca955x.c
@@ -129,6 +129,7 @@ struct pca955x_led {
        int                     led_num;        /* 0 .. 15 potentially */
        char                    name[32];
        u32                     type;
+       int                     default_state;
        const char              *default_trigger;
 };
 
@@ -439,6 +440,7 @@ pca955x_get_pdata(struct i2c_client *client, struct pca955x_chipdef *chip)
 
        device_for_each_child_node(&client->dev, child) {
                const char *name;
+               const char *state;
                u32 reg;
                int res;
 
@@ -457,6 +459,18 @@ pca955x_get_pdata(struct i2c_client *client, struct pca955x_chipdef *chip)
                fwnode_property_read_u32(child, "type", &led->type);
                fwnode_property_read_string(child, "linux,default-trigger",
                                            &led->default_trigger);
+
+               if (!fwnode_property_read_string(child, "default-state",
+                                                &state)) {
+                       if (!strcmp(state, "keep"))
+                               led->default_state = LEDS_GPIO_DEFSTATE_KEEP;
+                       else if (!strcmp(state, "on"))
+                               led->default_state = LEDS_GPIO_DEFSTATE_ON;
+                       else
+                               led->default_state = LEDS_GPIO_DEFSTATE_OFF;
+               } else {
+                       led->default_state = LEDS_GPIO_DEFSTATE_OFF;
+               }
        }
 
        pdata->num_leds = chip->bits;
@@ -485,6 +499,7 @@ static int pca955x_probe(struct i2c_client *client,
        int i, err;
        struct pca955x_platform_data *pdata;
        int ngpios = 0;
+       bool keep_pwm = false;
 
        chip = &pca955x_chipdefs[id->driver_data];
        adapter = client->adapter;
@@ -565,14 +580,35 @@ static int pca955x_probe(struct i2c_client *client,
                        led->brightness_set_blocking = pca955x_led_set;
                        led->brightness_get = pca955x_led_get;
 
+                       if (pdata->leds[i].default_state ==
+                           LEDS_GPIO_DEFSTATE_OFF) {
+                               err = pca955x_led_set(led, LED_OFF);
+                               if (err)
+                                       return err;
+                       } else if (pdata->leds[i].default_state ==
+                                  LEDS_GPIO_DEFSTATE_ON) {
+                               err = pca955x_led_set(led, LED_FULL);
+                               if (err)
+                                       return err;
+                       }
+
                        err = devm_led_classdev_register(&client->dev, led);
                        if (err)
                                return err;
 
-                       /* Turn off LED */
-                       err = pca955x_led_set(led, LED_OFF);
-                       if (err)
-                               return err;
+                       /*
+                        * For default-state == "keep", let the core update the
+                        * brightness from the hardware, then check the
+                        * brightness to see if it's using PWM1. If so, PWM1
+                        * should not be written below.
+                        */
+                       if (pdata->leds[i].default_state ==
+                           LEDS_GPIO_DEFSTATE_KEEP) {
+                               if (led->brightness != LED_FULL &&
+                                   led->brightness != LED_OFF &&
+                                   led->brightness != LED_HALF)
+                                       keep_pwm = true;
+                       }
                }
        }
 
@@ -581,10 +617,12 @@ static int pca955x_probe(struct i2c_client *client,
        if (err)
                return err;
 
-       /* PWM1 is used for variable brightness, default to OFF */
-       err = pca955x_write_pwm(client, 1, 0);
-       if (err)
-               return err;
+       if (!keep_pwm) {
+               /* PWM1 is used for variable brightness, default to OFF */
+               err = pca955x_write_pwm(client, 1, 0);
+               if (err)
+                       return err;
+       }
 
        /* Set to fast frequency so we do not see flashing */
        err = pca955x_write_psc(client, 0, 0);