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Date:   Tue, 24 Jan 2017 23:51:23 +0100
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     sean.wang@...iatek.com, rpurdie@...ys.net, lee.jones@...aro.org,
        matthias.bgg@...il.com, pavel@....cz, robh+dt@...nel.org,
        mark.rutland@....com
Cc:     devicetree@...r.kernel.org, linux-leds@...r.kernel.org,
        linux-mediatek@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        keyhaede@...il.com
Subject: Re: [PATCH 3/4] leds: Add LED support for MT6323 PMIC

Hi Sean,

Thanks for the patch. Please find my comments in the code below.

On 01/23/2017 04:54 AM, sean.wang@...iatek.com wrote:
> From: Sean Wang <sean.wang@...iatek.com>
> 
> MT6323 PMIC is a multi-function device that includes
> LED function. It allows attaching upto 4 LEDs which can

s/upto/up to/

> either be on, off or dimmed and/or blinked with the the
> controller.
> 
> Signed-off-by: Sean Wang <sean.wang@...iatek.com>
> ---
>  drivers/leds/Kconfig       |   8 +
>  drivers/leds/Makefile      |   1 +
>  drivers/leds/leds-mt6323.c | 391 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 400 insertions(+)
>  create mode 100644 drivers/leds/leds-mt6323.c
> 
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index c621cbb..30095fc 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -117,6 +117,14 @@ config LEDS_MIKROTIK_RB532
>  	  This option enables support for the so called "User LED" of
>  	  Mikrotik's Routerboard 532.
>  
> +config LEDS_MT6323
> +	tristate "LED Support for Mediatek MT6323 PMIC"
> +	depends on LEDS_CLASS
> +	depends on MFD_MT6397
> +
> +	help
> +	  This option enables support for on-chip LED drivers found on
> +	  Mediatek MT6323 PMIC.
> +
>  config LEDS_S3C24XX
>  	tristate "LED Support for Samsung S3C24XX GPIO LEDs"
>  	depends on LEDS_CLASS
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index 6b82737..4feb332 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -72,6 +72,7 @@ obj-$(CONFIG_LEDS_IS31FL32XX)		+= leds-is31fl32xx.o
>  obj-$(CONFIG_LEDS_PM8058)		+= leds-pm8058.o
>  obj-$(CONFIG_LEDS_MLXCPLD)		+= leds-mlxcpld.o
>  obj-$(CONFIG_LEDS_NIC78BX)		+= leds-nic78bx.o
> +obj-$(CONFIG_LEDS_MT6323)		+= leds-mt6323.o
>  
>  # LED SPI Drivers
>  obj-$(CONFIG_LEDS_DAC124S085)		+= leds-dac124s085.o
> diff --git a/drivers/leds/leds-mt6323.c b/drivers/leds/leds-mt6323.c
> new file mode 100644
> index 0000000..de3006d
> --- /dev/null
> +++ b/drivers/leds/leds-mt6323.c
> @@ -0,0 +1,391 @@
> +/*
> + * LED driver for Mediatek MT6323 PMIC
> + *
> + * Copyright (C) 2017 Sean Wang <sean.wang@...iatek.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation; either version 2 of
> + * the License, or (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/leds.h>
> +#include <linux/regmap.h>
> +#include <linux/mfd/mt6397/core.h>
> +#include <linux/mfd/mt6323/registers.h>
> +#include <linux/module.h>

Please sort include directives alphabetically.

> +
> +/* Register to enable 32K clock common for LED device */
> +#define MTK_MT6323_TOP_CKPDN0         0x0102

How about dropping MTK and leaving MT6323 prefix?
The same applies to the other macros.

> +#define RG_DRV_32K_CK_PDN	      BIT(11)
> +#define RG_DRV_32K_CK_PDN_MASK	      BIT(11)

These macros also require MT6323 prefix.

> +
> +/* Register to enable individual clock for LED device */
> +#define MTK_MT6323_TOP_CKPDN2         0x010E
> +#define RG_ISINK_CK_PDN(i)	      BIT(i)
> +#define RG_ISINK_CK_PDN_MASK(i)       BIT(i)
> +
> +/* Register to select clock source */
> +#define MTK_MT6323_TOP_CKCON1	      0x0126
> +#define RG_ISINK_CK_SEL_MASK(i)	      (BIT(10) << (i))
> +
> +/* Register to setup the duty cycle of the blink */
> +#define MTK_MT6323_ISINK_CON0(i)      (0x0330 + 0x8 * (i))
> +#define ISINK_DIM_DUTY(i)	      (((i) << 8) & GENMASK(12, 8))
> +#define ISINK_DIM_DUTY_MASK	      GENMASK(12, 8)
> +
> +/* Register to setup the period of the blink */
> +#define MTK_MT6323_ISINK_CON1(i)      (0x0332 + 0x8 * (i))
> +#define ISINK_DIM_FSEL(i)	      ((i) & GENMASK(15, 0))
> +#define ISINK_DIM_FSEL_MASK	      GENMASK(15, 0)
> +
> +/* Register to control the brightness */
> +#define MTK_MT6323_ISINK_CON2(i)      (0x0334 + 0x8 * (i))
> +#define ISINK_CH_STEP(i)	      (((i) << 12) & GENMASK(14, 12))
> +#define ISINK_CH_STEP_MASK	      GENMASK(14, 12)
> +#define ISINK_SFSTR0_TC(i)	      (((i) << 1) & GENMASK(2, 1))
> +#define ISINK_SFSTR0_TC_MASK	      GENMASK(2, 1)
> +#define ISINK_SFSTR0_EN		      BIT(0)
> +#define ISINK_SFSTR0_EN_MASK	      BIT(0)
> +
> +/* Register to LED channel enablement */
> +#define MTK_MT6323_ISINK_EN_CTRL      0x0356
> +#define ISINK_CH_EN(i)		      BIT(i)
> +#define ISINK_CH_EN_MASK(i)	      BIT(i)
> +
> +#define MTK_MAX_PERIOD		      10000
> +#define MTK_MAX_DEVICES			  4
> +#define MTK_MAX_BRIGHTNESS		  6
> +
> +struct mtk_led;

This is redundant.

> +struct mtk_leds;
> +
> +/**
> + * struct mtk_led - state container for the LED device
> + * @id: the identifier in MT6323 LED device
> + * @parent: the pointer to MT6323 LED controller
> + * @cdev: LED class device for this LED device
> + * @current_brightness: current state of the LED device
> + */
> +struct mtk_led {
> +	int    id;
> +	struct mtk_leds *parent;
> +	struct led_classdev cdev;
> +	u8 current_brightness;
> +};
> +
> +/* struct mtk_leds -	state container for holding LED controller

Please stick to the kernel doc format consistently:

/**
 *

> + *			of the driver
> + * @dev:		The device pointer
> + * @hw:			The underlying hardware providing shared
> +			bus for the register operations

leading " *" is missing here

> + * @led_num:		How much the LED device the controller could control
> + * @lock:		The lock among process context
> + * @led:		The array that contains the state of individual
> +			LED device

Ditto.

> + */
> +struct mtk_leds {
> +	struct device	*dev;
> +	struct mt6397_chip *hw;
> +	u8     led_num;
> +	/* protect among process context */
> +	struct mutex	 lock;
> +	struct mtk_led	 led[4];
> +};
> +
> +static void mtk_led_hw_off(struct led_classdev *cdev)
> +{
> +	struct mtk_led *led = container_of(cdev, struct mtk_led, cdev);
> +	struct mtk_leds *leds = led->parent;
> +	struct regmap *regmap = leds->hw->regmap;
> +	unsigned int status;
> +
> +	status = ISINK_CH_EN(led->id);
> +	regmap_update_bits(regmap, MTK_MT6323_ISINK_EN_CTRL,
> +			   ISINK_CH_EN_MASK(led->id), ~status);

Let's check return value. The same applies the other occurrences
of regmap API calls.

> +
> +	usleep_range(100, 300);

Just out of curiosity - does the data sheet mention it or is it inferred
empirically?

> +	regmap_update_bits(regmap, MTK_MT6323_TOP_CKPDN2,
> +			   RG_ISINK_CK_PDN_MASK(led->id),
> +			   RG_ISINK_CK_PDN(led->id));
> +
> +	dev_dbg(leds->dev, "%s called for led%d\n",
> +		__func__, led->id);

Let's remove this debug logging.

> +}
> +
> +static u8 get_mtk_led_hw_brightness(struct led_classdev *cdev)
> +{
> +	struct mtk_led *led = container_of(cdev, struct mtk_led, cdev);
> +	struct mtk_leds *leds = led->parent;
> +	struct regmap *regmap = leds->hw->regmap;
> +	unsigned int status;
> +
> +	regmap_read(regmap, MTK_MT6323_TOP_CKPDN2, &status);
> +	if (status & RG_ISINK_CK_PDN_MASK(led->id))
> +		return 0;
> +
> +	regmap_read(regmap, MTK_MT6323_ISINK_EN_CTRL, &status);
> +	if (!(status & ISINK_CH_EN(led->id)))
> +		return 0;
> +
> +	regmap_read(regmap, MTK_MT6323_ISINK_CON2(led->id), &status);
> +	return  ((status & ISINK_CH_STEP_MASK) >> 12) + 1;

What is 12? Please add a macro for it.

> +}
> +
> +static void mtk_led_hw_on(struct led_classdev *cdev)
> +{
> +	struct mtk_led *led = container_of(cdev, struct mtk_led, cdev);
> +	struct mtk_leds *leds = led->parent;
> +	struct regmap *regmap = leds->hw->regmap;
> +	unsigned int status;
> +
> +	/* Setup required clock source, enable the corresponding

Kernel style comments please:

/*
 *
 */

The same applies to the other occurrences thereof.
Refer to Documentation/process/coding-style.rst (chapter 8).

> +	 * clock and channel and let work with continuous blink as
> +	 * the default
> +	 */
> +	regmap_update_bits(regmap, MTK_MT6323_TOP_CKCON1,
> +			   RG_ISINK_CK_SEL_MASK(led->id), 0);
> +
> +	status = RG_ISINK_CK_PDN(led->id);
> +	regmap_update_bits(regmap, MTK_MT6323_TOP_CKPDN2,
> +			   RG_ISINK_CK_PDN_MASK(led->id), ~status);
> +
> +	usleep_range(100, 300);
> +
> +	regmap_update_bits(regmap, MTK_MT6323_ISINK_EN_CTRL,
> +			   ISINK_CH_EN_MASK(led->id),
> +			   ISINK_CH_EN(led->id));
> +
> +	regmap_update_bits(regmap, MTK_MT6323_ISINK_CON2(led->id),
> +			   ISINK_CH_STEP_MASK,
> +			   ISINK_CH_STEP(1));
> +
> +	regmap_update_bits(regmap, MTK_MT6323_ISINK_CON0(led->id),
> +			   ISINK_DIM_DUTY_MASK, ISINK_DIM_DUTY(31));
> +
> +	regmap_update_bits(regmap, MTK_MT6323_ISINK_CON1(led->id),
> +			   ISINK_DIM_FSEL_MASK, ISINK_DIM_FSEL(1000));
> +
> +	led->current_brightness = 1;
> +
> +	dev_dbg(leds->dev, "%s called for led%d\n",
> +		__func__, led->id);

Let's remove this debug logging.

> +}
> +
> +static int mtk_led_set_blink(struct led_classdev *cdev,
> +			     unsigned long *delay_on,
> +			     unsigned long *delay_off)
> +{
> +	struct mtk_led *led = container_of(cdev, struct mtk_led, cdev);
> +	struct mtk_leds *leds = led->parent;
> +	struct regmap *regmap = leds->hw->regmap;
> +	u16 period;
> +	u8 duty_cycle, duty_hw;
> +
> +	/* Units are in ms , if over the hardware able
> +	 * to support, fallback into software blink
> +	 */
> +	if (*delay_on + *delay_off > MTK_MAX_PERIOD)
> +		return -EINVAL;
> +
> +	/* LED subsystem requires a default user
> +	 * friendly blink pattern for the LED so using
> +	 * 1Hz duty cycle 50% here if without specific
> +	 * value delay_on and delay off being assigned
> +	 */
> +	if (*delay_on == 0 && *delay_off == 0) {
> +		*delay_on = 500;
> +		*delay_off = 500;
> +	}
> +
> +	period = *delay_on + *delay_off;
> +
> +	/* duty_cycle is the percentage of period during
> +	 * which the led is ON
> +	 */
> +	duty_cycle = 100 * (*delay_on) / period;
> +
> +	mutex_lock(&leds->lock);
> +
> +	if (!led->current_brightness)
> +		mtk_led_hw_on(cdev);
> +
> +	duty_hw = DIV_ROUND_CLOSEST(duty_cycle * 1000, 3125);

Please add a macro for 3125.

> +	regmap_update_bits(regmap, MTK_MT6323_ISINK_CON0(led->id),
> +			   ISINK_DIM_DUTY_MASK, ISINK_DIM_DUTY(duty_hw));
> +
> +	regmap_update_bits(regmap, MTK_MT6323_ISINK_CON1(led->id),
> +			   ISINK_DIM_FSEL_MASK, ISINK_DIM_FSEL(period - 1));
> +
> +	mutex_unlock(&leds->lock);
> +
> +	dev_dbg(leds->dev, "%s: Hardware blink! period=%dms duty=%d for led%d\n",
> +		__func__, period, duty_cycle, led->id);

Let's remove this debug logging.

> +
> +	return 0;
> +}
> +
> +static int mtk_led_set_brightness(struct led_classdev *cdev,
> +				  enum led_brightness brightness)
> +{
> +	struct mtk_led *led = container_of(cdev, struct mtk_led, cdev);
> +	struct mtk_leds *leds = led->parent;
> +	struct regmap *regmap = leds->hw->regmap;
> +
> +	mutex_lock(&leds->lock);
> +
> +	if (!led->current_brightness && brightness)
> +		mtk_led_hw_on(cdev);
> +
> +	if (brightness) {
> +		/* Setup current output for the corresponding
> +		 * brightness level
> +		 */
> +		regmap_update_bits(regmap, MTK_MT6323_ISINK_CON2(led->id),
> +				   ISINK_CH_STEP_MASK,
> +				   ISINK_CH_STEP(brightness - 1));
> +
> +		regmap_update_bits(regmap, MTK_MT6323_ISINK_CON2(led->id),
> +				   ISINK_SFSTR0_TC_MASK | ISINK_SFSTR0_EN_MASK,
> +				   ISINK_SFSTR0_TC(2) | ISINK_SFSTR0_EN);
> +
> +		dev_dbg(leds->dev, "Update led brightness:%d\n",
> +			brightness);

Let's remove this debug logging.

> +	}
> +
> +	if (!brightness)
> +		mtk_led_hw_off(cdev);

It could be enclosed in "else " case of the above "if (brightness)"
condition.

> +	led->current_brightness = brightness;
> +
> +	mutex_unlock(&leds->lock);
> +
> +	return 0;
> +}
> +
> +static int mt6323_led_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *np = pdev->dev.of_node;
> +	struct device_node *child;
> +	struct mt6397_chip *hw = dev_get_drvdata(pdev->dev.parent);
> +	struct mtk_leds *leds;
> +	int ret, i = 0, count;
> +	const char *state;
> +	unsigned int status;
> +
> +	count = of_get_child_count(np);
> +	if (!count)
> +		return -ENODEV;
> +
> +	/* The number the LEDs on MT6323 could be support is
> +	 * up to MTK_MAX_DEVICES
> +	 */
> +	count = (count <= MTK_MAX_DEVICES) ? count : MTK_MAX_DEVICES;
> +
> +	leds = devm_kzalloc(dev, sizeof(struct mtk_leds) +
> +			    sizeof(struct mtk_led) * count,
> +			    GFP_KERNEL);
> +	if (!leds)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, leds);
> +	leds->dev = dev;
> +
> +	/* leds->hw points to the underlying bus for the register
> +	 * controlled
> +	 */
> +	leds->hw = hw;
> +	mutex_init(&leds->lock);
> +	leds->led_num = count;
> +
> +	status = RG_DRV_32K_CK_PDN;
> +	regmap_update_bits(leds->hw->regmap, MTK_MT6323_TOP_CKPDN0,
> +			   RG_DRV_32K_CK_PDN_MASK, ~status);
> +
> +	/* Waiting for 32K stable prior to give the default value

Could you shed more light on this statement? How data sheet explains
that?

> +	 * to each LED state decided through these useful common
> +	 * propertys such as label, linux,default-trigger and

s/propertys/properties/

> +	 * default-state
> +	 */
> +	usleep_range(300, 500);
> +
> +	for_each_available_child_of_node(np, child) {
> +		leds->led[i].cdev.name =
> +			of_get_property(child, "label", NULL) ? :
> +					child->name;
> +		leds->led[i].cdev.default_trigger = of_get_property(child,
> +						    "linux,default-trigger",
> +						    NULL);
> +		leds->led[i].cdev.max_brightness = MTK_MAX_BRIGHTNESS;
> +		leds->led[i].cdev.brightness_set_blocking =
> +					mtk_led_set_brightness;
> +		leds->led[i].cdev.blink_set = mtk_led_set_blink;
> +		leds->led[i].id = i;
> +		leds->led[i].parent = leds;
> +		state = of_get_property(child, "default-state", NULL);
> +		if (state) {
> +			if (!strcmp(state, "keep")) {
> +				leds->led[i].current_brightness =
> +				get_mtk_led_hw_brightness(&leds->led[i].cdev);
> +			} else if (!strcmp(state, "on")) {
> +				mtk_led_set_brightness(&leds->led[i].cdev, 1);
> +			} else  {
> +				mtk_led_set_brightness(&leds->led[i].cdev,
> +						       0);
> +			}
> +		}
> +		ret = devm_led_classdev_register(dev, &leds->led[i].cdev);
> +		if (ret) {
> +			dev_err(&pdev->dev, "Failed to register LED: %d\n",
> +				ret);
> +			return ret;
> +		}
> +		leds->led[i].cdev.dev->of_node = child;
> +		i++;
> +	}
> +
> +	return 0;
> +}
> +
> +static int mt6323_led_remove(struct platform_device *pdev)
> +{
> +	struct mtk_leds *leds = platform_get_drvdata(pdev);
> +	int i;
> +
> +	/* Turned the LED to OFF state if driver removal */

s/if/on/

> +	for (i = 0 ; i < leds->led_num ; i++)
> +		mtk_led_hw_off(&leds->led[i].cdev);
> +
> +	regmap_update_bits(leds->hw->regmap, MTK_MT6323_TOP_CKPDN0,
> +			   RG_DRV_32K_CK_PDN_MASK, RG_DRV_32K_CK_PDN);

Please add mutex_destroy here.

> +	return 0;
> +}
> +
> +static const struct of_device_id mt6323_led_dt_match[] = {
> +	{ .compatible = "mediatek,mt6323-led" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, mt6323_led_dt_match);
> +
> +static struct platform_driver mt6323_led_driver = {
> +	.probe		= mt6323_led_probe,
> +	.remove		= mt6323_led_remove,
> +	.driver		= {
> +		.name	= "mt6323-led",
> +		.of_match_table = mt6323_led_dt_match,
> +	},
> +};
> +
> +module_platform_driver(mt6323_led_driver);
> +
> +MODULE_DESCRIPTION("LED driver for Mediatek MT6323 PMIC");
> +MODULE_AUTHOR("Sean Wang <sean.wang@...iatek.com>");
> +MODULE_LICENSE("GPL v2");

MODULE_LICENSE("GPL") since you are allowing also later version.

Please also adress the following sparse warnings:

drivers/leds/leds-mt6323.c:166:9: warning: cast truncates bits from
constant value (7ffffffff000 becomes fffff000)
drivers/leds/leds-mt6323.c:170:9: warning: cast truncates bits from
constant value (1fffffffff00 becomes ffffff00)
drivers/leds/leds-mt6323.c:173:9: warning: cast truncates bits from
constant value (ffffffffffff becomes ffffffff)
drivers/leds/leds-mt6323.c:221:9: warning: cast truncates bits from
constant value (1fffffffff00 becomes ffffff00)
drivers/leds/leds-mt6323.c:224:9: warning: cast truncates bits from
constant value (ffffffffffff becomes ffffffff)
drivers/leds/leds-mt6323.c:251:17: warning: cast truncates bits from
constant value (7ffffffff000 becomes fffff000)
drivers/leds/leds-mt6323.c:255:17: warning: cast truncates bits from
constant value (7ffffffff becomes ffffffff

-- 
Best regards,
Jacek Anaszewski

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