leds: turris-omnia: Add support for enabling/disabling HW gamma correction

If the MCU on Turris Omnia is running newer firmware versions, the LED
controller supports RGB gamma correction (and enables it by default for
newer boards).

Determine whether the gamma correction setting feature is supported and
add the ability to set it via sysfs attribute file.

Signed-off-by: Marek Behún <kabel@kernel.org>
Link: https://lore.kernel.org/r/20230918161104.20860-5-kabel@kernel.org
Signed-off-by: Lee Jones <lee@kernel.org>

diff --git a/Documentation/ABI/testing/sysfs-class-led-driver-turris-omnia b/Documentation/ABI/testing/sysfs-class-led-driver-turris-omnia
index c4d46970c1cf923ae12341e5cef2333f2dc08667..369b4ae8be5f43e8eda648f2896e83f870510007 100644 (file)
--- a/Documentation/ABI/testing/sysfs-class-led-driver-turris-omnia
+++ b/Documentation/ABI/testing/sysfs-class-led-driver-turris-omnia
@@ -12,3 +12,17 @@ Description: (RW) On the front panel of the Turris Omnia router there is also
                able to change this setting from software.
 
                Format: %i
+
+What:          /sys/class/leds/<led>/device/gamma_correction
+Date:          August 2023
+KernelVersion: 6.6
+Contact:       Marek Behún <kabel@kernel.org>
+Description:   (RW) Newer versions of the microcontroller firmware of the
+               Turris Omnia router support gamma correction for the RGB LEDs.
+               This feature can be enabled/disabled by writing to this file.
+
+               If the feature is not supported because the MCU firmware is too
+               old, the file always reads as 0, and writing to the file results
+               in the EOPNOTSUPP error.
+
+               Format: %i

diff --git a/drivers/leds/leds-turris-omnia.c b/drivers/leds/leds-turris-omnia.c
index ef2844d351683e6f544cd073993d668e198252af..f27241896970a3d207735ebd89c69833f18fb3aa 100644 (file)
--- a/drivers/leds/leds-turris-omnia.c
+++ b/drivers/leds/leds-turris-omnia.c
@@ -15,17 +15,30 @@
 #define OMNIA_BOARD_LEDS       12
 #define OMNIA_LED_NUM_CHANNELS 3
 
-#define CMD_LED_MODE           3
-#define CMD_LED_MODE_LED(l)    ((l) & 0x0f)
-#define CMD_LED_MODE_USER      0x10
+/* MCU controller commands at I2C address 0x2a */
+#define OMNIA_MCU_I2C_ADDR             0x2a
 
-#define CMD_LED_STATE          4
-#define CMD_LED_STATE_LED(l)   ((l) & 0x0f)
-#define CMD_LED_STATE_ON       0x10
+#define CMD_GET_STATUS_WORD            0x01
+#define STS_FEATURES_SUPPORTED         BIT(2)
 
-#define CMD_LED_COLOR          5
-#define CMD_LED_SET_BRIGHTNESS 7
-#define CMD_LED_GET_BRIGHTNESS 8
+#define CMD_GET_FEATURES               0x10
+#define FEAT_LED_GAMMA_CORRECTION      BIT(5)
+
+/* LED controller commands at I2C address 0x2b */
+#define CMD_LED_MODE                   0x03
+#define CMD_LED_MODE_LED(l)            ((l) & 0x0f)
+#define CMD_LED_MODE_USER              0x10
+
+#define CMD_LED_STATE                  0x04
+#define CMD_LED_STATE_LED(l)           ((l) & 0x0f)
+#define CMD_LED_STATE_ON               0x10
+
+#define CMD_LED_COLOR                  0x05
+#define CMD_LED_SET_BRIGHTNESS         0x07
+#define CMD_LED_GET_BRIGHTNESS         0x08
+
+#define CMD_SET_GAMMA_CORRECTION       0x30
+#define CMD_GET_GAMMA_CORRECTION       0x31
 
 struct omnia_led {
        struct led_classdev_mc mc_cdev;
@@ -40,6 +53,7 @@ struct omnia_led {
 struct omnia_leds {
        struct i2c_client *client;
        struct mutex lock;
+       bool has_gamma_correction;
        struct omnia_led leds[];
 };
 
@@ -50,30 +64,42 @@ static int omnia_cmd_write_u8(const struct i2c_client *client, u8 cmd, u8 val)
        return i2c_master_send(client, buf, sizeof(buf));
 }
 
-static int omnia_cmd_read_u8(const struct i2c_client *client, u8 cmd)
+static int omnia_cmd_read_raw(struct i2c_adapter *adapter, u8 addr, u8 cmd,
+                             void *reply, size_t len)
 {
        struct i2c_msg msgs[2];
-       u8 reply;
        int ret;
 
-       msgs[0].addr = client->addr;
+       msgs[0].addr = addr;
        msgs[0].flags = 0;
        msgs[0].len = 1;
        msgs[0].buf = &cmd;
-       msgs[1].addr = client->addr;
+       msgs[1].addr = addr;
        msgs[1].flags = I2C_M_RD;
-       msgs[1].len = 1;
-       msgs[1].buf = &reply;
+       msgs[1].len = len;
+       msgs[1].buf = reply;
 
-       ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+       ret = i2c_transfer(adapter, msgs, ARRAY_SIZE(msgs));
        if (likely(ret == ARRAY_SIZE(msgs)))
-               return reply;
+               return len;
        else if (ret < 0)
                return ret;
        else
                return -EIO;
 }
 
+static int omnia_cmd_read_u8(const struct i2c_client *client, u8 cmd)
+{
+       u8 reply;
+       int ret;
+
+       ret = omnia_cmd_read_raw(client->adapter, client->addr, cmd, &reply, 1);
+       if (ret < 0)
+               return ret;
+
+       return reply;
+}
+
 static int omnia_led_send_color_cmd(const struct i2c_client *client,
                                    struct omnia_led *led)
 {
@@ -352,12 +378,74 @@ static ssize_t brightness_store(struct device *dev, struct device_attribute *a,
 }
 static DEVICE_ATTR_RW(brightness);
 
+static ssize_t gamma_correction_show(struct device *dev,
+                                    struct device_attribute *a, char *buf)
+{
+       struct i2c_client *client = to_i2c_client(dev);
+       struct omnia_leds *leds = i2c_get_clientdata(client);
+       int ret;
+
+       if (leds->has_gamma_correction) {
+               ret = omnia_cmd_read_u8(client, CMD_GET_GAMMA_CORRECTION);
+               if (ret < 0)
+                       return ret;
+       } else {
+               ret = 0;
+       }
+
+       return sysfs_emit(buf, "%d\n", !!ret);
+}
+
+static ssize_t gamma_correction_store(struct device *dev,
+                                     struct device_attribute *a,
+                                     const char *buf, size_t count)
+{
+       struct i2c_client *client = to_i2c_client(dev);
+       struct omnia_leds *leds = i2c_get_clientdata(client);
+       bool val;
+       int ret;
+
+       if (!leds->has_gamma_correction)
+               return -EOPNOTSUPP;
+
+       if (kstrtobool(buf, &val) < 0)
+               return -EINVAL;
+
+       ret = omnia_cmd_write_u8(client, CMD_SET_GAMMA_CORRECTION, val);
+
+       return ret < 0 ? ret : count;
+}
+static DEVICE_ATTR_RW(gamma_correction);
+
 static struct attribute *omnia_led_controller_attrs[] = {
        &dev_attr_brightness.attr,
+       &dev_attr_gamma_correction.attr,
        NULL,
 };
 ATTRIBUTE_GROUPS(omnia_led_controller);
 
+static int omnia_mcu_get_features(const struct i2c_client *client)
+{
+       u16 reply;
+       int err;
+
+       err = omnia_cmd_read_raw(client->adapter, OMNIA_MCU_I2C_ADDR,
+                                CMD_GET_STATUS_WORD, &reply, sizeof(reply));
+       if (err < 0)
+               return err;
+
+       /* Check whether MCU firmware supports the CMD_GET_FEAUTRES command */
+       if (!(le16_to_cpu(reply) & STS_FEATURES_SUPPORTED))
+               return 0;
+
+       err = omnia_cmd_read_raw(client->adapter, OMNIA_MCU_I2C_ADDR,
+                                CMD_GET_FEATURES, &reply, sizeof(reply));
+       if (err < 0)
+               return err;
+
+       return le16_to_cpu(reply);
+}
+
 static int omnia_leds_probe(struct i2c_client *client)
 {
        struct device *dev = &client->dev;
@@ -382,6 +470,21 @@ static int omnia_leds_probe(struct i2c_client *client)
        leds->client = client;
        i2c_set_clientdata(client, leds);
 
+       ret = omnia_mcu_get_features(client);
+       if (ret < 0) {
+               dev_err(dev, "Cannot determine MCU supported features: %d\n",
+                       ret);
+               return ret;
+       }
+
+       leds->has_gamma_correction = ret & FEAT_LED_GAMMA_CORRECTION;
+       if (!leds->has_gamma_correction) {
+               dev_info(dev,
+                        "Your board's MCU firmware does not support the LED gamma correction feature.\n");
+               dev_info(dev,
+                        "Consider upgrading MCU firmware with the omnia-mcutool utility.\n");
+       }
+
        mutex_init(&leds->lock);
 
        ret = devm_led_trigger_register(dev, &omnia_hw_trigger);