Re: [PATCH 2/2] leds: Add Spreadtrum SC27xx breathing light controller driver

From: Jacek Anaszewski
Date: Mon May 07 2018 - 16:14:51 EST

Hi Baolin,

Thank you for the patch. Generally this is a nice and clean driver,
but I noticed some locking related issues and one detail
regarding LED naming. Please refer below.

On 05/04/2018 12:08 PM, Baolin Wang wrote:
From: Xiaotong Lu <xiaotong.lu@xxxxxxxxxxxxxx>

This patch adds Spreadtrum SC27xx PMIC series breathing light controller
driver, which can support 3 LEDs. Each LED can work at normal PWM mode
and breathing mode.

Signed-off-by: Xiaotong Lu <xiaotong.lu@xxxxxxxxxxxxxx>
Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxx>
---
drivers/leds/Kconfig | 11 ++
drivers/leds/Makefile | 1 +
drivers/leds/leds-sc27xx-bltc.c | 369 +++++++++++++++++++++++++++++++++++++++
3 files changed, 381 insertions(+)
create mode 100644 drivers/leds/leds-sc27xx-bltc.c

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 2c896c0..319449b 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -647,6 +647,17 @@ config LEDS_IS31FL32XX
LED controllers. They are I2C devices with multiple constant-current
channels, each with independent 256-level PWM control.
+config LEDS_SC27XX_BLTC
+ tristate "LED support for the SC27xx breathing light controller"
+ depends on LEDS_CLASS && MFD_SC27XX_PMIC
+ depends on OF
+ help
+ Say Y here to include support for the SC27xx breathing light controller
+ LEDs.
+
+ This driver can also be built as a module. If so the module will be
+ called leds-sc27xx-bltc.
+
comment "LED driver for blink(1) USB RGB LED is under Special HID drivers (HID_THINGM)"
config LEDS_BLINKM
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index 91eca81..ff6917e 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -76,6 +76,7 @@ obj-$(CONFIG_LEDS_MLXREG) += leds-mlxreg.o
obj-$(CONFIG_LEDS_NIC78BX) += leds-nic78bx.o
obj-$(CONFIG_LEDS_MT6323) += leds-mt6323.o
obj-$(CONFIG_LEDS_LM3692X) += leds-lm3692x.o
+obj-$(CONFIG_LEDS_SC27XX_BLTC) += leds-sc27xx-bltc.o
# LED SPI Drivers
obj-$(CONFIG_LEDS_DAC124S085) += leds-dac124s085.o
diff --git a/drivers/leds/leds-sc27xx-bltc.c b/drivers/leds/leds-sc27xx-bltc.c
new file mode 100644
index 0000000..0016a87
--- /dev/null
+++ b/drivers/leds/leds-sc27xx-bltc.c
@@ -0,0 +1,369 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 Spreadtrum Communications Inc.
+ */

Please use uniform "//" comment style here.

+
+#include <linux/leds.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+/* PMIC global control register definition */
+#define SC27XX_MODULE_EN0 0xc08
+#define SC27XX_CLK_EN0 0xc18
+#define SC27XX_RGB_CTRL 0xebc
+
+#define SC27XX_BLTC_EN BIT(9)
+#define SC27XX_RTC_EN BIT(7)
+#define SC27XX_RGB_PD BIT(0)
+
+/* Breathing light controller register definition */
+#define SC27XX_LEDS_CTRL 0x00
+#define SC27XX_LEDS_PRESCALE 0x04
+#define SC27XX_LEDS_DUTY 0x08
+#define SC27XX_LEDS_CURVE0 0x0c
+#define SC27XX_LEDS_CURVE1 0x10
+
+#define SC27XX_CTRL_SHIFT 4
+#define SC27XX_LED_RUN BIT(0)
+#define SC27XX_LED_TYPE BIT(1)
+
+#define SC27XX_DUTY_SHIFT 8
+#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
+
+/*
+ * The SC27xx breathing light controller can support 3 outputs: red LED,
+ * green LED and blue LED. Each LED can support normal PWM mode and breathing
+ * mode.
+ *
+ * In breathing mode, the LED output curve includes raise, high, fall and low 4
+ * stages, and the duration of each stage is configurable.
+ */
+enum sc27xx_led_config {
+ SC27XX_RAISE_TIME,
+ SC27XX_FALL_TIME,
+ SC27XX_HIGH_TIME,
+ SC27XX_LOW_TIME,
+};
+
+struct sc27xx_led {
+ struct led_classdev ldev;
+ struct sc27xx_led_priv *priv;
+ enum led_brightness value;
+ u8 line;
+ bool breath_mode;
+ bool active;
+};
+
+struct sc27xx_led_priv {
+ struct sc27xx_led leds[SC27XX_LEDS_MAX];
+ struct regmap *regmap;
+ u32 base;
+};
+
+#define to_sc27xx_led(ldev) \
+ container_of(ldev, struct sc27xx_led, ldev)
+
+static int sc27xx_led_init(struct regmap *regmap)
+{
+ int err;
+
+ err = regmap_update_bits(regmap, SC27XX_MODULE_EN0, SC27XX_BLTC_EN,
+ SC27XX_BLTC_EN);
+ if (err)
+ return err;
+
+ err = regmap_update_bits(regmap, SC27XX_CLK_EN0, SC27XX_RTC_EN,
+ SC27XX_RTC_EN);
+ if (err)
+ return err;
+
+ return regmap_update_bits(regmap, SC27XX_RGB_CTRL, SC27XX_RGB_PD, 0);
+}
+
+static u32 sc27xx_led_get_offset(struct sc27xx_led *leds)
+{
+ return leds->priv->base + SC27XX_LEDS_OFFSET * leds->line;
+}
+
+static int sc27xx_led_enable(struct sc27xx_led *leds)
+{
+ 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;
+
+ err = regmap_update_bits(regmap, base + SC27XX_LEDS_DUTY,
+ SC27XX_DUTY_MASK,
+ (leds->value << SC27XX_DUTY_SHIFT) |
+ SC27XX_MOD_MASK);
+ if (err)
+ return err;
+
+ if (leds->breath_mode)
+ return regmap_update_bits(regmap, ctrl_base,
+ SC27XX_LED_RUN << ctrl_shift,
+ SC27XX_LED_RUN << ctrl_shift);
+
+ return regmap_update_bits(regmap, ctrl_base,
+ (SC27XX_LED_RUN | SC27XX_LED_TYPE) << ctrl_shift,
+ (SC27XX_LED_RUN | SC27XX_LED_TYPE) << ctrl_shift);
+}
+
+static int sc27xx_led_disable(struct sc27xx_led *leds)
+{
+ u8 ctrl_shift = SC27XX_CTRL_SHIFT * leds->line;
+
+ leds->breath_mode = false;
+
+ return regmap_update_bits(leds->priv->regmap,
+ leds->priv->base + SC27XX_LEDS_CTRL,
+ (SC27XX_LED_RUN | SC27XX_LED_TYPE) << ctrl_shift, 0);
+}
+
+static int sc27xx_led_set(struct led_classdev *ldev, enum led_brightness value)
+{
+ struct sc27xx_led *leds = to_sc27xx_led(ldev);

You need mutex protection here to ensure that the device will
not be left in an inconsistent state in case of concurrent access
from userspace.

+ leds->value = value;
+ if (value == LED_OFF)
+ return sc27xx_led_disable(leds);
+
+ return sc27xx_led_enable(leds);
+}
+
+static int sc27xx_led_config(struct sc27xx_led *leds,
+ enum sc27xx_led_config config, u32 val)
+{
+ u32 base = sc27xx_led_get_offset(leds);
+ struct regmap *regmap = leds->priv->regmap;
+ int err;
+
+ switch (config) {
+ case SC27XX_RAISE_TIME:
+ err = regmap_update_bits(regmap, base + SC27XX_LEDS_CURVE0,
+ SC27XX_CURVE_L_MASK, val);
+ break;
+ case SC27XX_FALL_TIME:
+ err = regmap_update_bits(regmap, base + SC27XX_LEDS_CURVE0,
+ SC27XX_CURVE_H_MASK,
+ val << SC27XX_CURVE_SHIFT);
+ break;
+ case SC27XX_HIGH_TIME:
+ err = regmap_update_bits(regmap, base + SC27XX_LEDS_CURVE1,
+ SC27XX_CURVE_L_MASK, val);
+ break;
+ case SC27XX_LOW_TIME:
+ err = regmap_update_bits(regmap, base + SC27XX_LEDS_CURVE1,
+ SC27XX_CURVE_H_MASK,
+ val << SC27XX_CURVE_SHIFT);
+ break;
+ default:
+ err = -ENOTSUPP;
+ break;
+ }

Ditto.

+
+ if (!err && !leds->breath_mode)
+ leds->breath_mode = true;
+
+ return err;
+}
+
+static ssize_t raise_time_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ struct led_classdev *ldev = dev_get_drvdata(dev);
+ struct sc27xx_led *leds = to_sc27xx_led(ldev);
+ u32 val;
+ int err;
+
+ if (kstrtou32(buf, 10, &val))
+ return -EINVAL;
+
+ err = sc27xx_led_config(leds, SC27XX_RAISE_TIME, val);
+ if (err)
+ return err;
+
+ return size;
+}
+
+static ssize_t fall_time_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ struct led_classdev *ldev = dev_get_drvdata(dev);
+ struct sc27xx_led *leds = to_sc27xx_led(ldev);
+ u32 val;
+ int err;
+
+ if (kstrtou32(buf, 10, &val))
+ return -EINVAL;
+
+ err = sc27xx_led_config(leds, SC27XX_FALL_TIME, val);
+ if (err)
+ return err;
+
+ return size;
+}
+
+static ssize_t high_time_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ struct led_classdev *ldev = dev_get_drvdata(dev);
+ struct sc27xx_led *leds = to_sc27xx_led(ldev);
+ u32 val;
+ int err;
+
+ if (kstrtou32(buf, 10, &val))
+ return -EINVAL;
+
+ err = sc27xx_led_config(leds, SC27XX_HIGH_TIME, val);
+ if (err)
+ return err;
+
+ return size;
+}
+
+static ssize_t low_time_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t size)
+{
+ struct led_classdev *ldev = dev_get_drvdata(dev);
+ struct sc27xx_led *leds = to_sc27xx_led(ldev);
+ u32 val;
+ int err;
+
+ if (kstrtou32(buf, 10, &val))
+ return -EINVAL;
+
+ err = sc27xx_led_config(leds, SC27XX_LOW_TIME, val);
+ if (err)
+ return err;
+
+ return size;
+}
+
+static DEVICE_ATTR_WO(raise_time);
+static DEVICE_ATTR_WO(fall_time);
+static DEVICE_ATTR_WO(high_time);
+static DEVICE_ATTR_WO(low_time);
+
+static struct attribute *sc27xx_led_attrs[] = {
+ &dev_attr_raise_time.attr,
+ &dev_attr_fall_time.attr,
+ &dev_attr_high_time.attr,
+ &dev_attr_low_time.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(sc27xx_led);

Please add ABI documentation for this sysfs interface.

+static int sc27xx_led_register(struct device *dev, struct sc27xx_led_priv *priv)
+{
+ int i, err;
+
+ err = sc27xx_led_init(priv->regmap);
+ if (err)
+ return err;
+
+ for (i = 0; i < SC27XX_LEDS_MAX; i++) {
+ struct sc27xx_led *led = &priv->leds[i];
+
+ if (!led->active)
+ continue;
+
+ led->line = i;
+ led->priv = priv;
+ led->ldev.brightness_set_blocking = sc27xx_led_set;
+ led->ldev.max_brightness = LED_FULL;
+ led->ldev.groups = sc27xx_led_groups;
+
+ err = devm_led_classdev_register(dev, &led->ldev);
+ if (err)
+ return err;
+ }
+
+ return 0;
+}
+
+static int sc27xx_led_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct device_node *np = dev->of_node, *child;
+ struct sc27xx_led_priv *priv;
+ u32 base, count, reg;
+ int err;
+
+ count = of_get_child_count(np);
+ if (!count || count > SC27XX_LEDS_MAX)
+ return -EINVAL;
+
+ err = of_property_read_u32(np, "reg", &base);
+ if (err) {
+ dev_err(dev, "fail to get reg of property\n");
+ return err;
+ }
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ priv->base = base;
+ priv->regmap = dev_get_regmap(dev->parent, NULL);
+ if (IS_ERR(priv->regmap)) {
+ err = PTR_ERR(priv->regmap);
+ dev_err(dev, "failed to get regmap: %d\n", err);
+ return err;
+ }
+
+ for_each_child_of_node(np, child) {
+ err = of_property_read_u32(child, "reg", &reg);
+ if (err) {
+ of_node_put(child);
+ return err;
+ }
+
+ if (reg < 0 || reg >= SC27XX_LEDS_MAX
+ || priv->leds[reg].active) {
+ of_node_put(child);
+ return -EINVAL;
+ }
+
+ priv->leds[reg].active = true;
+ priv->leds[reg].ldev.name =
+ of_get_property(child, "label", NULL) ? : child->name;

LED class device naming pattern requires devicename section.
Please use "sc27xx::" for the case when label is not available
and concatenate "sc27xx:" with the child->name otherwise.

You can refer to drivers/leds/leds-cr0014114.c in this regard.
We're sorting out issues around LED class device naming, so this
is quite new approach.

+ }
+
+ return sc27xx_led_register(dev, priv);
+}
+
+static const struct of_device_id sc27xx_led_of_match[] = {
+ { .compatible = "sprd,sc27xx-bltc", },
+ { }
+};
+MODULE_DEVICE_TABLE(of, sc27xx_led_of_match);
+
+static struct platform_driver sc27xx_led_driver = {
+ .driver = {
+ .name = "sc27xx-bltc",
+ .of_match_table = sc27xx_led_of_match,
+ },
+ .probe = sc27xx_led_probe,
+};
+
+module_platform_driver(sc27xx_led_driver);
+
+MODULE_DESCRIPTION("Spreadtrum SC27xx breathing light controller driver");
+MODULE_AUTHOR("Xiaotong Lu <xiaotong.lu@xxxxxxxxxxxxxx>");
+MODULE_LICENSE("GPL v2");


--
Best regards,
Jacek Anaszewski