Now that the core logic is in place, let's add support to
adjust the S0 brightness level.

Signed-off-by: Mauro Carvalho Chehab <mchehab+hua...@kernel.org>
---
 drivers/staging/nuc-led/nuc-wmi.c | 79 +++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)

diff --git a/drivers/staging/nuc-led/nuc-wmi.c 
b/drivers/staging/nuc-led/nuc-wmi.c
index b75ddd47e443..62c2764814dd 100644
--- a/drivers/staging/nuc-led/nuc-wmi.c
+++ b/drivers/staging/nuc-led/nuc-wmi.c
@@ -392,7 +392,85 @@ static ssize_t store_indicator(struct device *dev,
        return -EINVAL;
 }
 
+/* Get S0 brightness */
+static ssize_t show_s0_brightness(struct device *dev,
+                                 struct device_attribute *attr,
+                                 char *buf)
+{
+       struct led_classdev *cdev = dev_get_drvdata(dev);
+       struct nuc_nmi_led *led = container_of(cdev, struct nuc_nmi_led, cdev);
+       u8 cmd, input[NUM_INPUT_ARGS] = { 0 };
+       u8 output[NUM_OUTPUT_ARGS];
+       int ret;
+
+       cmd = LED_NEW_GET_STATUS;
+       input[0] = LED_NEW_GET_CONTROL_ITEM;
+       input[1] = led->id;
+       input[2] = led->indicator;
+       input[3] = 0;
+
+       ret = nuc_nmi_cmd(dev, cmd, input, output);
+       if (ret)
+               return ret;
+
+       /* Multicolor uses a scale from 0 to 100 */
+       if (led->color_type & (LED_BLUE_AMBER | LED_BLUE_WHITE | LED_RGB))
+               return scnprintf(buf, PAGE_SIZE, "%d%%\n", output[0]);
+
+       /* single color uses 0, 50% and 100% */
+       return scnprintf(buf, PAGE_SIZE, "%d%%\n", output[0] * 50);
+}
+
+/* Change S0 brightness */
+static ssize_t store_s0_brightness(struct device *dev,
+                                  struct device_attribute *attr,
+                                  const char *buf, size_t len)
+{
+       struct led_classdev *cdev = dev_get_drvdata(dev);
+       struct nuc_nmi_led *led = container_of(cdev, struct nuc_nmi_led, cdev);
+       u8 cmd, input[NUM_INPUT_ARGS] = { 0 };
+       int ret;
+       u8 val;
+
+       if (led->indicator == LED_IND_DISABLE) {
+               dev_dbg(dev, "Led %s is disabled. ignoring it.\n", cdev->name);
+               return -EACCES;
+       }
+
+       if (kstrtou8(buf, 0, &val) || val > 100)
+               return -EINVAL;
+
+       /*
+        * For single-color LEDs, the value should be between 0 to 2, but,
+        * in order to have a consistent API, let's always handle it as if
+        * it is a percentage, for both multicolor and single color LEDs.
+        * So:
+        *      value == 0 will disable the LED
+        *      value up to 74% will set it the brightness to 50%
+        *      value equal or above 75% will use the maximum brightness.
+        */
+       if (!(led->color_type & (LED_BLUE_AMBER | LED_BLUE_WHITE | LED_RGB))) {
+               if (val > 0 && val < 75)
+                       val = 1;
+               if (val >= 75)
+                       val = 2;
+       }
+
+       cmd = LED_SET_VALUE;
+       input[0] = led->id;
+       input[1] = led->indicator;
+       input[2] = 0;           /* FIXME: replace by an enum */
+       input[3] = val;
+
+       ret = nuc_nmi_cmd(dev, cmd, input, NULL);
+       if (ret)
+               return ret;
+
+       return len;
+}
+
 static LED_ATTR_RW(indicator);
+static LED_ATTR_RW(s0_brightness);
 
 /*
  * Attributes for multicolor LEDs
@@ -400,6 +478,7 @@ static LED_ATTR_RW(indicator);
 
 static struct attribute *nuc_wmi_multicolor_led_attr[] = {
        &dev_attr_indicator.attr,
+       &dev_attr_s0_brightness.attr,
        NULL,
 };
 
-- 
2.31.1

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