2 files changed, 40 insertions, 0 deletions

diff --git a/drivers/leds/leds-lp55xx-common.c b/drivers/leds/leds-lp55xx-common.c
index 715a6027316f..ba34199dc3d9 100644
--- a/drivers/leds/leds-lp55xx-common.c
+++ b/drivers/leds/leds-lp55xx-common.c
@@ -12,6 +12,7 @@
  * Derived from leds-lp5521.c, leds-lp5523.c
  */
 
+#include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/firmware.h>
 #include <linux/i2c.h>
@@ -21,6 +22,9 @@
 
 #include "leds-lp55xx-common.h"
 
+/* External clock rate */
+#define LP55XX_CLK_32K                  32768
+
 static struct lp55xx_led *cdev_to_lp55xx_led(struct led_classdev *cdev)
 {
         return container_of(cdev, struct lp55xx_led, cdev);
@@ -357,6 +361,35 @@ int lp55xx_update_bits(struct lp55xx_chip *chip, u8 reg, u8 mask, u8 val)
 }
 EXPORT_SYMBOL_GPL(lp55xx_update_bits);
 
+bool lp55xx_is_extclk_used(struct lp55xx_chip *chip)
+{
+        struct clk *clk;
+        int err;
+
+        clk = devm_clk_get(&chip->cl->dev, "32k_clk");
+        if (IS_ERR(clk))
+                goto use_internal_clk;
+
+        err = clk_prepare_enable(clk);
+        if (err)
+                goto use_internal_clk;
+
+        if (clk_get_rate(clk) != LP55XX_CLK_32K) {
+                clk_disable_unprepare(clk);
+                goto use_internal_clk;
+        }
+
+        dev_info(&chip->cl->dev, "%dHz external clock used\n",  LP55XX_CLK_32K);
+
+        chip->clk = clk;
+        return true;
+
+use_internal_clk:
+        dev_info(&chip->cl->dev, "internal clock used\n");
+        return false;
+}
+EXPORT_SYMBOL_GPL(lp55xx_is_extclk_used);
+
 int lp55xx_init_device(struct lp55xx_chip *chip)
 {
         struct lp55xx_platform_data *pdata;
@@ -421,6 +454,9 @@ void lp55xx_deinit_device(struct lp55xx_chip *chip)
 {
         struct lp55xx_platform_data *pdata = chip->pdata;
 
+        if (chip->clk)
+                clk_disable_unprepare(chip->clk);
+
         if (pdata->enable)
                 pdata->enable(0);
 
diff --git a/drivers/leds/leds-lp55xx-common.h b/drivers/leds/leds-lp55xx-common.h
index ece4761a1302..fa6a078bf547 100644
--- a/drivers/leds/leds-lp55xx-common.h
+++ b/drivers/leds/leds-lp55xx-common.h
@@ -83,6 +83,7 @@ struct lp55xx_device_config {
  */
 struct lp55xx_chip {
         struct i2c_client *cl;
+        struct clk *clk;
         struct lp55xx_platform_data *pdata;
         struct mutex lock;      /* lock for user-space interface */
         int num_leds;
@@ -117,6 +118,9 @@ extern int lp55xx_read(struct lp55xx_chip *chip, u8 reg, u8 *val);
 extern int lp55xx_update_bits(struct lp55xx_chip *chip, u8 reg,
                         u8 mask, u8 val);
 
+/* external clock detection */
+extern bool lp55xx_is_extclk_used(struct lp55xx_chip *chip);
+
 /* common device init/deinit functions */
 extern int lp55xx_init_device(struct lp55xx_chip *chip);
 extern void lp55xx_deinit_device(struct lp55xx_chip *chip);