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From:   Baolin Wang <baolin.wang@linaro.org>
Date:   Tue, 8 May 2018 10:21:16 +0800
Message-ID: <CAMz4kuK4EXO2iwBgsOUwZ2rzh0bwvpFwvr6K7U7YpFz=M8gdAw@mail.gmail.com>
Subject: Re: [PATCH 2/2] leds: Add Spreadtrum SC27xx breathing light
 controller driver
To:     Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc:     Pavel Machek <pavel@ucw.cz>, Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        xiaotong.lu@spreadtrum.com, Mark Brown <broonie@kernel.org>,
        linux-leds@vger.kernel.org, DTML <devicetree@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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Sender: linux-kernel-owner@vger.kernel.org
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Hi Jacek,

On 8 May 2018 at 04:13, Jacek Anaszewski <jacek.anaszewski@gmail.com> wrote:
> 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@spreadtrum.com>
>>
>> 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@spreadtrum.com>
>> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
>> ---
>>   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.

Indeed, will add one lock in next version.

>
>
>> +       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.

OK.

>
>
>> +
>> +       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.

OK.

>
>
>> +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.

Make sense. Will fix it in next version. Thanks for your helpful comments.

-- 
Baolin.wang
Best Regards