Message-ID: <1485612301.29021.43.camel@mtkswgap22>
Date:   Sat, 28 Jan 2017 22:05:01 +0800
From:   Sean Wang <sean.wang@...iatek.com>
To:     Jacek Anaszewski <jacek.anaszewski@...il.com>
CC:     <rpurdie@...ys.net>, <lee.jones@...aro.org>,
        <matthias.bgg@...il.com>, <pavel@....cz>, <robh+dt@...nel.org>,
        <mark.rutland@....com>, <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 Jacek,

thanks for your effort on reviewing
I has given these idea about your questions inline below
and will fix up these explicit mistakes in the next version. 

thanks again

On Tue, 2017-01-24 at 23:51 +0100, Jacek Anaszewski wrote:
> 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/
> 
will be fixed

> > 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.
> 
will be fixed

> > +
> > +/* 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.

MT6323_TOP_CKPDN0 had been defined in regulator header files
but your idea is good where reusing them is better . 

Will be enhanced.


> > +#define RG_DRV_32K_CK_PDN	      BIT(11)
> > +#define RG_DRV_32K_CK_PDN_MASK	      BIT(11)
> 
> These macros also require MT6323 prefix.

Will be enhanced

> > +
> > +/* 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.
> 
Will be fixed

> > +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:
> 
> /**
>  *

Will be fixed

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

Will be fixed

> > + * @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.
> 

Will be fixed

> > + */
> > +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.


Will be fixed and applied to all the occurrences where regmap API being 
used.

> > +
> > +	usleep_range(100, 300);
> 
> Just out of curiosity - does the data sheet mention it or is it inferred
> empirically?
> 

it comes from that inferred empirically. 
leds can't being light on if without the delay

> > +	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.
> 

will be removed 

> > +}
> > +
> > +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.
> 

will be fixed

> > +}
> > +
> > +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).
> 

will be fixed and applied to all occurrences

> > +	 * 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.
> 

will be removed

> > +}
> > +
> > +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.
> 

will be fixed

> > +	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.
> 

will be removed

> > +
> > +	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.
> 

will be removed

> > +	}
> > +
> > +	if (!brightness)
> > +		mtk_led_hw_off(cdev);
> 
> It could be enclosed in "else " case of the above "if (brightness)"
> condition.
> 
good suggestion. will be enhanced

> > +	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?

it is also from inferred empirically but that could be removed
because 32k clock should be stable before the hardware is being 
enabled.

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

will be fixed

> > +	 * 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/

will be fixed
> > +	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.
> 

will be fixed
> > +	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.
> 

will be fixed

> 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
> 

will be fixed

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