Date:	Wed, 23 May 2012 10:40:00 +0900
From:	jonghwa3.lee@...sung.com
To:	yadi.brar01@...il.com
Cc:	linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Liam Girdwood <lrg@...com>,
	Yadwinder Singh Brar <yadi.brar@...sung.com>
Subject: Re: [PATCH v3 2/2] regulator: Add support for MAX77686.

Hi, Yadwinder,
As you know, both of us, recently, had competition for one driver
whether you intend or not. And now, i think it is time to stop this and
to find appropriate goal. From now on, i won't update this driver no
more. I recommend you to review my patch and apply feature that you can
apply. And also check comments that i wrote below.

On 2012년 05월 22일 14:57, yadi.brar01@...il.com wrote:

> From: Yadwinder Singh Brar <yadi.brar@...sung.com>
> 
> Add support for PMIC/regulator portion of MAX77686 multifunction device.
> MAX77686 provides LDOs[1-26] and BUCKs[1-9]. This is initial release of driv
> which supports setting and getting the voltage of a regulator with I2C
> interface.
> 
> Signed-off-by: Yadwinder Singh Brar <yadi.brar@...sung.com>
> ---
>  drivers/regulator/Kconfig    |    9 +
>  drivers/regulator/Makefile   |    1 +
>  drivers/regulator/max77686.c |  387 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 397 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/regulator/max77686.c
> 
> diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
> index c86b886..e8f9417 100644
> --- a/drivers/regulator/Kconfig
> +++ b/drivers/regulator/Kconfig
> @@ -195,6 +195,15 @@ config REGULATOR_MAX8998
>  	  via I2C bus. The provided regulator is suitable for S3C6410
>  	  and S5PC1XX chips to control VCC_CORE and VCC_USIM voltages.
>  
> +config REGULATOR_MAX77686
> +	tristate "Maxim 77686 regulator"
> +	depends on MFD_MAX77686
> +	help
> +	  This driver controls a Maxim 77686 voltage regulator via I2C
> +	  bus. The provided regulator is suitable for Exynos5 chips to
> +	  control VDD_ARM and VDD_INT voltages.It supports LDOs[1-26]
> +	  and BUCKs[1-9].
> +
>  config REGULATOR_PCAP
>  	tristate "Motorola PCAP2 regulator driver"
>  	depends on EZX_PCAP
> diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
> index 977fd46..d854453 100644
> --- a/drivers/regulator/Makefile
> +++ b/drivers/regulator/Makefile
> @@ -30,6 +30,7 @@ obj-$(CONFIG_REGULATOR_MAX8925) += max8925-regulator.o
>  obj-$(CONFIG_REGULATOR_MAX8952) += max8952.o
>  obj-$(CONFIG_REGULATOR_MAX8997) += max8997.o
>  obj-$(CONFIG_REGULATOR_MAX8998) += max8998.o
> +obj-$(CONFIG_REGULATOR_MAX77686) += max77686.o
>  obj-$(CONFIG_REGULATOR_MC13783) += mc13783-regulator.o
>  obj-$(CONFIG_REGULATOR_MC13892) += mc13892-regulator.o
>  obj-$(CONFIG_REGULATOR_MC13XXX_CORE) +=  mc13xxx-regulator-core.o
> diff --git a/drivers/regulator/max77686.c b/drivers/regulator/max77686.c
> new file mode 100644
> index 0000000..98dbd50
> --- /dev/null
> +++ b/drivers/regulator/max77686.c
> @@ -0,0 +1,387 @@
> +/*
> + * max77686.c - Regulator driver for the Maxim 77686
> + *
> + * Copyright (C) 2012 Samsung Electronics Co. Ltd.
> + * Chiwoong Byun <woong.byun@...sung.com>
> + * Yadwinder Singh Brar <yadi.brar@...sung.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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
> + *
> + * This driver is based on max8997.c
> + */
> +
> +#include <linux/module.h>
> +#include <linux/bug.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/gpio.h>
> +#include <linux/slab.h>
> +#include <linux/platform_device.h>
> +#include <linux/regulator/driver.h>
> +#include <linux/regulator/machine.h>
> +#include <linux/regulator/of_regulator.h>
> +#include <linux/mfd/max77686.h>
> +#include <linux/mfd/max77686-private.h>
> +
> +struct max77686_data {
> +	struct device *dev;
> +	struct max77686_dev *iodev;
> +	int num_regulators;
> +	struct regulator_dev **rdev;
> +	int ramp_delay;		/* index of ramp_delay */
> +
> +	/*GPIO-DVS feature is not enabled with the
> +	 *current version of MAX77686 driver.*/
> +};
> +
> +static int max77686_voltage_dvs_buck_time_sel(struct regulator_dev *rdev,
> +					unsigned int old_sel,
> +					unsigned int new_sel)
> +{
> +	struct max77686_data *max77686 = rdev_get_drvdata(rdev);
> +	int ramp[] = {13, 27, 55, 100};	/* ramp_rate in mV/uS */
> +
> +	return DIV_ROUND_UP(rdev->desc->uV_step *
> +			    abs(new_sel - old_sel),
> +			    ramp[max77686->ramp_delay]);
> +}
> +
> +static int max77686_voltage_time_sel(struct regulator_dev *rdev,
> +					unsigned int old_sel,
> +					unsigned int new_sel)
> +{
> +	return DIV_ROUND_UP(rdev->desc->uV_step *
> +			    abs(new_sel - old_sel),
> +			    100);
> +}
> +


Does LDO also need waiting for voltage change? I afraid it's not.

> +static struct regulator_ops max77686_ops = {
> +	.map_voltage		= regulator_map_voltage_linear,
> +	.list_voltage		= regulator_list_voltage_linear,
> +	.is_enabled		= regulator_is_enabled_regmap,
> +	.enable			= regulator_enable_regmap,
> +	.disable		= regulator_disable_regmap,
> +	.get_voltage_sel	= regulator_get_voltage_sel_regmap,
> +	.set_voltage_sel	= regulator_set_voltage_sel_regmap,
> +	.set_voltage_time_sel	= max77686_voltage_time_sel,
> +};
> +
> +static struct regulator_ops max77686_buck_ops = {
> +	.map_voltage		= regulator_map_voltage_linear,
> +	.list_voltage		= regulator_list_voltage_linear,
> +	.is_enabled		= regulator_is_enabled_regmap,
> +	.enable			= regulator_enable_regmap,
> +	.disable		= regulator_disable_regmap,
> +	.get_voltage_sel	= regulator_get_voltage_sel_regmap,
> +	.set_voltage_sel	= regulator_set_voltage_sel_regmap,
> +	.set_voltage_time_sel	= max77686_voltage_dvs_buck_time_sel,
> +};
> +
> +#define regulator_desc_ldo(num)		{				\
> +	.name		= "LDO"#num,					\
> +	.id		= MAX77686_LDO##num,				\
> +	.ops		= &max77686_ops,				\
> +	.type		= REGULATOR_VOLTAGE,				\
> +	.owner		= THIS_MODULE,					\
> +	.min_uV		= 800000,					\
> +	.uV_step	= 50000,					\
> +	.n_voltages	= 64,						\
> +	.vsel_reg	= MAX77686_REG_LDO1CTRL1 + num - 1,		\
> +	.vsel_mask	= 0x3f,						\
> +	.enable_reg	= MAX77686_REG_LDO1CTRL1 + num - 1,		\
> +	.enable_mask	= 0x0c,						\
> +}
> +#define regulator_desc_ldo_low_vol(num)	{				\
> +	.name		= "LDO"#num,					\
> +	.id		= MAX77686_LDO##num,				\
> +	.ops		= &max77686_ops,				\
> +	.type		= REGULATOR_VOLTAGE,				\
> +	.owner		= THIS_MODULE,					\
> +	.min_uV		= 800000,					\
> +	.uV_step	= 25000,					\
> +	.n_voltages	= 64,						\
> +	.vsel_reg	= MAX77686_REG_LDO1CTRL1 + num - 1,		\
> +	.vsel_mask	= 0x3f,						\
> +	.enable_reg	= MAX77686_REG_LDO1CTRL1 + num - 1,		\
> +	.enable_mask	= 0x0c,						\
> +}
> +#define regulator_desc_buck(num)	{				\
> +	.name		= "BUCK"#num,					\
> +	.id		= MAX77686_BUCK##num,				\
> +	.ops		= &max77686_ops,				\
> +	.type		= REGULATOR_VOLTAGE,				\
> +	.owner		= THIS_MODULE,					\
> +	.min_uV		= 750000,					\
> +	.uV_step	= 50000,					\
> +	.n_voltages	= 64,						\
> +	.vsel_reg	= MAX77686_REG_BUCK5OUT + (num - 5) * 2,	\
> +	.vsel_mask	= 0x3f,						\
> +	.enable_reg	= MAX77686_REG_BUCK5CTRL + (num - 5) * 2,	\
> +	.enable_mask	= 0x03,						\
> +}
> +#define regulator_desc_buck1(num)	{				\
> +	.name		= "BUCK"#num,					\
> +	.id		= MAX77686_BUCK##num,				\
> +	.ops		= &max77686_ops,				\
> +	.type		= REGULATOR_VOLTAGE,				\
> +	.owner		= THIS_MODULE,					\
> +	.min_uV		= 750000,					\
> +	.uV_step	= 50000,					\
> +	.n_voltages	= 64,						\
> +	.vsel_reg	= MAX77686_REG_BUCK1OUT,			\
> +	.vsel_mask	= 0x3f,						\
> +	.enable_reg	= MAX77686_REG_BUCK1CTRL,			\
> +	.enable_mask	= 0x03,						\
> +}
> +#define regulator_desc_buck_dvs(num)	{				\
> +	.name		= "BUCK"#num,					\
> +	.id		= MAX77686_BUCK##num,				\
> +	.ops		= &max77686_buck_ops,				\
> +	.type		= REGULATOR_VOLTAGE,				\
> +	.owner		= THIS_MODULE,					\
> +	.min_uV		= 600000,					\
> +	.uV_step	= 12500,					\
> +	.n_voltages	= 256,						\
> +	.vsel_reg	= MAX77686_REG_BUCK2DVS1 + (num - 2) * 10,	\
> +	.vsel_mask	= 0xff,						\
> +	.enable_reg	= MAX77686_REG_BUCK2CTRL1 + (num - 2) * 10,	\
> +	.enable_mask	= 0x30,						\
> +}
> +
> +static struct regulator_desc regulators[] = {
> +	regulator_desc_ldo_low_vol(1),
> +	regulator_desc_ldo_low_vol(2),
> +	regulator_desc_ldo(3),
> +	regulator_desc_ldo(4),
> +	regulator_desc_ldo(5),
> +	regulator_desc_ldo_low_vol(6),
> +	regulator_desc_ldo_low_vol(7),
> +	regulator_desc_ldo_low_vol(8),
> +	regulator_desc_ldo(9),
> +	regulator_desc_ldo(10),
> +	regulator_desc_ldo(11),
> +	regulator_desc_ldo(12),
> +	regulator_desc_ldo(13),
> +	regulator_desc_ldo(14),
> +	regulator_desc_ldo(15),
> +	regulator_desc_ldo(16),
> +	regulator_desc_ldo(17),
> +	regulator_desc_ldo(18),
> +	regulator_desc_ldo(19),
> +	regulator_desc_ldo(20),
> +	regulator_desc_ldo(21),
> +	regulator_desc_ldo(22),
> +	regulator_desc_ldo(23),
> +	regulator_desc_ldo(24),
> +	regulator_desc_ldo(25),
> +	regulator_desc_ldo(26),
> +	regulator_desc_buck1(1),
> +	regulator_desc_buck_dvs(2),
> +	regulator_desc_buck_dvs(3),
> +	regulator_desc_buck_dvs(4),
> +	regulator_desc_buck(5),
> +	regulator_desc_buck(6),
> +	regulator_desc_buck(7),
> +	regulator_desc_buck(8),
> +	regulator_desc_buck(9),
> +};
> +
> +#ifdef CONFIG_OF
> +static int max77686_pmic_dt_parse_pdata(struct max77686_dev *iodev,
> +					struct max77686_platform_data *pdata)
> +{
> +	struct device_node *pmic_np, *regulators_np;
> +	struct of_regulator_match *rdata;
> +	unsigned int i, ret;
> +
> +	pmic_np = iodev->dev->of_node;
> +	if (!pmic_np) {
> +		dev_err(iodev->dev, "could not find pmic sub-node\n");
> +		return -ENODEV;
> +	}
> +
> +	regulators_np = of_find_node_by_name(pmic_np, "voltage-regulators");
> +	if (!regulators_np) {
> +		dev_err(iodev->dev, "could not find regulators sub-node\n");
> +		return -EINVAL;
> +	}
> +
> +	/* count the number of regulators to be supported in pmic */
> +	pdata->num_regulators = ARRAY_SIZE(regulators);
> +
> +	rdata = devm_kzalloc(iodev->dev, sizeof(*rdata) *
> +				(pdata->num_regulators), GFP_KERNEL);
> +	if (!rdata) {
> +		dev_err(iodev->dev,
> +			"could not allocate memory for regulator data\n");
> +		return -ENOMEM;
> +	}
> +
> +	for (i = 0; i < pdata->num_regulators; i++)
> +		rdata[i].name = regulators[i].name;
> +
> +	ret = of_regulator_match(iodev->dev, regulators_np, rdata,
> +				pdata->num_regulators);
> +
> +	if (ret < 0)
> +		dev_err(iodev->dev, "Parsing DT for regulators failed\n");
> +	else
> +		dev_info(iodev->dev, "regulators found in device tree : %d\n"
> +			, ret);
> +
> +	pdata->regulators = rdata;
> +
> +	if (of_property_read_u32(pmic_np, "max77686,buck_ramp_delay", &i))
> +		pdata->ramp_delay = i & 0xff;
> +
> +	return 0;
> +}
> +#else
> +static int max77686_pmic_dt_parse_pdata(struct max77686_dev *iodev,
> +					struct max77686_platform_data *pdata)
> +{
> +	return 0;
> +}
> +#endif	/* CONFIG_OF */
> +
> +static __devinit int max77686_pmic_probe(struct platform_device *pdev)
> +{
> +	struct max77686_dev *iodev = dev_get_drvdata(pdev->dev.parent);
> +	struct max77686_platform_data *pdata = iodev->pdata;
> +	struct regulator_dev **rdev;
> +	struct max77686_data *max77686;
> +	struct i2c_client *i2c = iodev->i2c;
> +	struct regulator_config config = { };
> +	int i, ret, size;
> +
> +	if (iodev->dev->of_node) {
> +		ret = max77686_pmic_dt_parse_pdata(iodev, pdata);
> +		if (ret)
> +			return ret;
> +	} else {			/* pdata from machine-setup file */
> +		if (!pdata) {
> +			dev_err(&pdev->dev, "platform data not found\n");
> +			return -ENODEV;
> +		} else {
> +			if (pdata->num_regulators != ARRAY_SIZE(regulators)) {
> +				dev_err(&pdev->dev,
> +					"incomplete regulator list\n");
> +				return -ENODEV;
> +			}
> +		}
> +	}
> +
> +	max77686 = devm_kzalloc(&pdev->dev, sizeof(struct max77686_data),
> +				GFP_KERNEL);
> +	if (!max77686)
> +		return -ENOMEM;
> +
> +	size = sizeof(struct regulator_dev *) * pdata->num_regulators;
> +	max77686->rdev = devm_kzalloc(&pdev->dev, size, GFP_KERNEL);
> +	if (!max77686->rdev) {
> +		kfree(max77686);
> +		return -ENOMEM;
> +	}
> +
> +	rdev = max77686->rdev;
> +
> +	max77686->dev = &pdev->dev;
> +	max77686->iodev = iodev;
> +	max77686->num_regulators = pdata->num_regulators;
> +
> +	if (pdata->ramp_delay < MAX77686_RAMP_RATE_13MV ||
> +		pdata->ramp_delay > MAX77686_RAMP_RATE_100MV)
> +		pdata->ramp_delay = MAX77686_RAMP_RATE_27MV;	/* default */
> +
> +	max77686->ramp_delay = pdata->ramp_delay - 1;


I think it is better to check pdata->ramp_delay is available.
If pdata doesn't have ramp_delay member it might be error.

> +	max77686_update_reg(i2c, MAX77686_REG_BUCK2CTRL1,
> +		max77686->ramp_delay << 6, RAMP_MASK);
> +	max77686_update_reg(i2c, MAX77686_REG_BUCK3CTRL1,
> +		max77686->ramp_delay << 6, RAMP_MASK);
> +	max77686_update_reg(i2c, MAX77686_REG_BUCK4CTRL1,
> +		max77686->ramp_delay << 6, RAMP_MASK);
> +


Why do you use i2c client still? If you registered regmap you can use
its API. I recommend you to use regmap_update_bits() directly.


> +	platform_set_drvdata(pdev, max77686);
> +
> +	for (i = 0; i < pdata->num_regulators; i++) {
> +		config.dev = max77686->dev;
> +		config.init_data = pdata->regulators[i].init_data;
> +		config.driver_data = max77686;
> +		config.regmap = iodev->regmap;
> +
> +		rdev[i] = regulator_register(&regulators[i], &config);
> +		if (IS_ERR(rdev[i])) {
> +			ret = PTR_ERR(rdev[i]);
> +			dev_err(max77686->dev,
> +				"regulator init failed for id : %d\n", i);
> +			rdev[i] = NULL;
> +			goto err;
> +		}
> +	}
> +
> +	return 0;
> + err:
> +	for (i = 0; i < max77686->num_regulators; i++)
> +		if (rdev[i])
> +			regulator_unregister(rdev[i]);
> +
> +	return ret;
> +}
> +
> +static int __devexit max77686_pmic_remove(struct platform_device *pdev)
> +{
> +	struct max77686_data *max77686 = platform_get_drvdata(pdev);
> +	struct regulator_dev **rdev = max77686->rdev;
> +	int i;
> +
> +	for (i = 0; i < max77686->num_regulators; i++)
> +		if (rdev[i])
> +			regulator_unregister(rdev[i]);
> +
> +	return 0;
> +}
> +
> +static const struct platform_device_id max77686_pmic_id[] = {
> +	{"max77686-pmic", 0},
> +	{},
> +};
> +MODULE_DEVICE_TABLE(platform, max77686_pmic_id);
> +
> +static struct platform_driver max77686_pmic_driver = {
> +	.driver = {
> +		   .name = "max77686-pmic",
> +		   .owner = THIS_MODULE,
> +		   },
> +	.probe = max77686_pmic_probe,
> +	.remove = __devexit_p(max77686_pmic_remove),
> +	.id_table = max77686_pmic_id,
> +};
> +
> +static int __init max77686_pmic_init(void)
> +{
> +	return platform_driver_register(&max77686_pmic_driver);
> +}
> +subsys_initcall(max77686_pmic_init);
> +
> +static void __exit max77686_pmic_cleanup(void)
> +{
> +	platform_driver_unregister(&max77686_pmic_driver);
> +}
> +module_exit(max77686_pmic_cleanup);
> +
> +MODULE_DESCRIPTION("MAXIM 77686 Regulator Driver");
> +MODULE_AUTHOR("Chiwoong Byun <woong.byun@...sung.com>");
> +MODULE_AUTHOR("Yadwinder Singh Brar <yadi.brar@...sung.com>");
> +MODULE_LICENSE("GPL");


MAX77686 has crystal oscillator in it. And original version of this
driver which was written by Chiwoon Byun, registers it as a regulator.
As Mark says, we have to change it to use generic clock API. Where do
you think should we put them into? In my opinion, it is proper that just
leave them in regulator driver because this driver is almost core of
PMIC. I already applied generic API in my local repository but i
couldn't test yet. Because it crashed with SOC's private clock API.
Anyway if you register 32khz clock with generic API ,DEFINE_CLK_GATE()
will help you out which defined in linux/clk-private.h.

Thanks.
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