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Subject[PATCH v15 2/2] leds: sc27xx: Add pattern_set/clear interfaces for LED controller
Date
This patch implements the 'pattern_set'and 'pattern_clear'
interfaces to support SC27XX LED breathing mode.

Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
Acked-by: Pavel Machek <pavel@ucw.c>
---
Chnages from v14:
- None.

Changes from v13:
- None.

Changes from v12:
- None.

Changes from v11:
- None.

Changes from v10:
- Add duration alignment function suggested by Jacek.
- Add acked tag from Pavel.

Changes from v9:
- Optimize the ABI documentation file.
- Update the brightness value in hardware pattern mode.

Changes from v8:
- Optimize the ABI documentation file.

Changes from v7:
- Add its own ABI documentation file.

Changes from v6:
- None.

Changes from v5:
- None.

Changes from v4:
- None.

Changes from v3:
- None.

Changes from v2:
- None.

Changes from v1:
- Remove pattern_get interface.
---
.../ABI/testing/sysfs-class-led-driver-sc27xx | 22 ++++
drivers/leds/leds-sc27xx-bltc.c | 121 ++++++++++++++++++++
2 files changed, 143 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-class-led-driver-sc27xx

diff --git a/Documentation/ABI/testing/sysfs-class-led-driver-sc27xx b/Documentation/ABI/testing/sysfs-class-led-driver-sc27xx
new file mode 100644
index 0000000..45b1e60
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-led-driver-sc27xx
@@ -0,0 +1,22 @@
+What: /sys/class/leds/<led>/hw_pattern
+Date: September 2018
+KernelVersion: 4.20
+Description:
+ Specify a hardware pattern for the SC27XX LED. For the SC27XX
+ LED controller, it only supports 4 stages to make a single
+ hardware pattern, which is used to configure the rise time,
+ high time, fall time and low time for the breathing mode.
+
+ For the breathing mode, the SC27XX LED only expects one brightness
+ for the high stage. To be compatible with the hardware pattern
+ format, we should set brightness as 0 for rise stage, fall
+ stage and low stage.
+
+ Min stage duration: 125 ms
+ Max stage duration: 31875 ms
+
+ Since the stage duration step is 125 ms, the duration should be
+ a multiplier of 125, like 125ms, 250ms, 375ms, 500ms ... 31875ms.
+
+ Thus the format of the hardware pattern values should be:
+ "0 rise_duration brightness high_duration 0 fall_duration 0 low_duration".
diff --git a/drivers/leds/leds-sc27xx-bltc.c b/drivers/leds/leds-sc27xx-bltc.c
index 9d9b7aa..fecf27f 100644
--- a/drivers/leds/leds-sc27xx-bltc.c
+++ b/drivers/leds/leds-sc27xx-bltc.c
@@ -32,8 +32,18 @@
#define SC27XX_DUTY_MASK GENMASK(15, 0)
#define SC27XX_MOD_MASK GENMASK(7, 0)

+#define SC27XX_CURVE_SHIFT 8
+#define SC27XX_CURVE_L_MASK GENMASK(7, 0)
+#define SC27XX_CURVE_H_MASK GENMASK(15, 8)
+
#define SC27XX_LEDS_OFFSET 0x10
#define SC27XX_LEDS_MAX 3
+#define SC27XX_LEDS_PATTERN_CNT 4
+/* Stage duration step, in milliseconds */
+#define SC27XX_LEDS_STEP 125
+/* Minimum and maximum duration, in milliseconds */
+#define SC27XX_DELTA_T_MIN SC27XX_LEDS_STEP
+#define SC27XX_DELTA_T_MAX (SC27XX_LEDS_STEP * 255)

struct sc27xx_led {
char name[LED_MAX_NAME_SIZE];
@@ -122,6 +132,113 @@ static int sc27xx_led_set(struct led_classdev *ldev, enum led_brightness value)
return err;
}

+static void sc27xx_led_clamp_align_delta_t(u32 *delta_t)
+{
+ u32 v, offset, t = *delta_t;
+
+ v = t + SC27XX_LEDS_STEP / 2;
+ v = clamp_t(u32, v, SC27XX_DELTA_T_MIN, SC27XX_DELTA_T_MAX);
+ offset = v - SC27XX_DELTA_T_MIN;
+ offset = SC27XX_LEDS_STEP * (offset / SC27XX_LEDS_STEP);
+
+ *delta_t = SC27XX_DELTA_T_MIN + offset;
+}
+
+static int sc27xx_led_pattern_clear(struct led_classdev *ldev)
+{
+ struct sc27xx_led *leds = to_sc27xx_led(ldev);
+ struct regmap *regmap = leds->priv->regmap;
+ u32 base = sc27xx_led_get_offset(leds);
+ u32 ctrl_base = leds->priv->base + SC27XX_LEDS_CTRL;
+ u8 ctrl_shift = SC27XX_CTRL_SHIFT * leds->line;
+ int err;
+
+ mutex_lock(&leds->priv->lock);
+
+ /* Reset the rise, high, fall and low time to zero. */
+ regmap_write(regmap, base + SC27XX_LEDS_CURVE0, 0);
+ regmap_write(regmap, base + SC27XX_LEDS_CURVE1, 0);
+
+ err = regmap_update_bits(regmap, ctrl_base,
+ (SC27XX_LED_RUN | SC27XX_LED_TYPE) << ctrl_shift, 0);
+
+ ldev->brightness = LED_OFF;
+
+ mutex_unlock(&leds->priv->lock);
+
+ return err;
+}
+
+static int sc27xx_led_pattern_set(struct led_classdev *ldev,
+ struct led_pattern *pattern,
+ u32 len, int repeat)
+{
+ struct sc27xx_led *leds = to_sc27xx_led(ldev);
+ u32 base = sc27xx_led_get_offset(leds);
+ u32 ctrl_base = leds->priv->base + SC27XX_LEDS_CTRL;
+ u8 ctrl_shift = SC27XX_CTRL_SHIFT * leds->line;
+ struct regmap *regmap = leds->priv->regmap;
+ int err;
+
+ /*
+ * Must contain 4 tuples to configure the rise time, high time, fall
+ * time and low time to enable the breathing mode.
+ */
+ if (len != SC27XX_LEDS_PATTERN_CNT)
+ return -EINVAL;
+
+ mutex_lock(&leds->priv->lock);
+
+ sc27xx_led_clamp_align_delta_t(&pattern[0].delta_t);
+ err = regmap_update_bits(regmap, base + SC27XX_LEDS_CURVE0,
+ SC27XX_CURVE_L_MASK,
+ pattern[0].delta_t / SC27XX_LEDS_STEP);
+ if (err)
+ goto out;
+
+ sc27xx_led_clamp_align_delta_t(&pattern[1].delta_t);
+ err = regmap_update_bits(regmap, base + SC27XX_LEDS_CURVE1,
+ SC27XX_CURVE_L_MASK,
+ pattern[1].delta_t / SC27XX_LEDS_STEP);
+ if (err)
+ goto out;
+
+ sc27xx_led_clamp_align_delta_t(&pattern[2].delta_t);
+ err = regmap_update_bits(regmap, base + SC27XX_LEDS_CURVE0,
+ SC27XX_CURVE_H_MASK,
+ (pattern[2].delta_t / SC27XX_LEDS_STEP) <<
+ SC27XX_CURVE_SHIFT);
+ if (err)
+ goto out;
+
+ sc27xx_led_clamp_align_delta_t(&pattern[3].delta_t);
+ err = regmap_update_bits(regmap, base + SC27XX_LEDS_CURVE1,
+ SC27XX_CURVE_H_MASK,
+ (pattern[3].delta_t / SC27XX_LEDS_STEP) <<
+ SC27XX_CURVE_SHIFT);
+ if (err)
+ goto out;
+
+ err = regmap_update_bits(regmap, base + SC27XX_LEDS_DUTY,
+ SC27XX_DUTY_MASK,
+ (pattern[1].brightness << SC27XX_DUTY_SHIFT) |
+ SC27XX_MOD_MASK);
+ if (err)
+ goto out;
+
+ /* Enable the LED breathing mode */
+ err = regmap_update_bits(regmap, ctrl_base,
+ SC27XX_LED_RUN << ctrl_shift,
+ SC27XX_LED_RUN << ctrl_shift);
+ if (!err)
+ ldev->brightness = pattern[1].brightness;
+
+out:
+ mutex_unlock(&leds->priv->lock);
+
+ return err;
+}
+
static int sc27xx_led_register(struct device *dev, struct sc27xx_led_priv *priv)
{
int i, err;
@@ -140,6 +257,9 @@ static int sc27xx_led_register(struct device *dev, struct sc27xx_led_priv *priv)
led->priv = priv;
led->ldev.name = led->name;
led->ldev.brightness_set_blocking = sc27xx_led_set;
+ led->ldev.pattern_set = sc27xx_led_pattern_set;
+ led->ldev.pattern_clear = sc27xx_led_pattern_clear;
+ led->ldev.default_trigger = "pattern";

err = devm_led_classdev_register(dev, &led->ldev);
if (err)
@@ -241,4 +361,5 @@ static int sc27xx_led_remove(struct platform_device *pdev)

MODULE_DESCRIPTION("Spreadtrum SC27xx breathing light controller driver");
MODULE_AUTHOR("Xiaotong Lu <xiaotong.lu@spreadtrum.com>");
+MODULE_AUTHOR("Baolin Wang <baolin.wang@linaro.org>");
MODULE_LICENSE("GPL v2");
--
1.7.9.5
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