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Date:   Tue, 18 Jul 2023 08:55:02 -0700
From:   Nathan Chancellor <nathan@kernel.org>
To:     Okan Sahin <okan.sahin@analog.com>
Cc:     Liam Girdwood <lgirdwood@gmail.com>,
        Mark Brown <broonie@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Ibrahim Tilki <Ibrahim.Tilki@analog.com>,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        llvm@lists.linux.dev
Subject: Re: [PATCH v3 2/2] regulator: max77857: Add ADI MAX77857/59/MAX77831
 Regulator Support
Message-ID: <20230718155502.GA3542993@dev-arch.thelio-3990X>
References: <20230717050736.10075-1-okan.sahin@analog.com>
 <20230717050736.10075-3-okan.sahin@analog.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20230717050736.10075-3-okan.sahin@analog.com>
Precedence: bulk

Hi Okan,

On Mon, Jul 17, 2023 at 08:07:35AM +0300, Okan Sahin wrote:
> Regulator driver for  MAX77857/59 and MAX77831.
> The MAX77857 is a high-efficiency, high-performance
> buck-boost converter targeted for systems requiring
> a wide input voltage range (2.5V to 16V).
> 
> The MAX77859 is high-Efficiency Buck-Boost Converter
> for USB-PD/PPS Applications. It has wide input range
> (2.5V to 22V)
> 
> The MAX77831 is a high-efficiency, high-performance
> buck-boost converter targeted for systems requiring
> wide input voltage range (2.5V to 16V).
> 
> Signed-off-by: Okan Sahin <okan.sahin@analog.com>
> ---
>  drivers/regulator/Kconfig              |  10 +
>  drivers/regulator/Makefile             |   1 +
>  drivers/regulator/max77857-regulator.c | 459 +++++++++++++++++++++++++
>  3 files changed, 470 insertions(+)
>  create mode 100644 drivers/regulator/max77857-regulator.c
> 
> diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
> index e5f3613c15fa..09eaa1cd90de 100644
> --- a/drivers/regulator/Kconfig
> +++ b/drivers/regulator/Kconfig
> @@ -573,6 +573,16 @@ config REGULATOR_MAX77650
>  	  Semiconductor. This device has a SIMO with three independent
>  	  power rails and an LDO.
>  
> +config REGULATOR_MAX77857
> +	tristate "ADI MAX77857/MAX77831 regulator support"
> +	depends on I2C
> +	select REGMAP_I2C
> +	help
> +	  This driver controls a ADI MAX77857 and MAX77831 regulators.
> +	  via I2C bus. MAX77857 and MAX77831 are high efficiency buck-boost
> +	  converters with input voltage range (2.5V to 16V). Say Y here to
> +	  enable the regulator driver
> +
>  config REGULATOR_MAX8649
>  	tristate "Maxim 8649 voltage regulator"
>  	depends on I2C
> diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
> index 58dfe0147cd4..e7230846b680 100644
> --- a/drivers/regulator/Makefile
> +++ b/drivers/regulator/Makefile
> @@ -85,6 +85,7 @@ obj-$(CONFIG_REGULATOR_MAX77686) += max77686-regulator.o
>  obj-$(CONFIG_REGULATOR_MAX77693) += max77693-regulator.o
>  obj-$(CONFIG_REGULATOR_MAX77802) += max77802-regulator.o
>  obj-$(CONFIG_REGULATOR_MAX77826) += max77826-regulator.o
> +obj-$(CONFIG_REGULATOR_MAX77857) += max77857-regulator.o
>  obj-$(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/max77857-regulator.c b/drivers/regulator/max77857-regulator.c
> new file mode 100644
> index 000000000000..c5482ffd606e
> --- /dev/null
> +++ b/drivers/regulator/max77857-regulator.c
> @@ -0,0 +1,459 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (c) 2023 Analog Devices, Inc.
> + * ADI Regulator driver for the MAX77857
> + * MAX77859 and MAX77831.
> + */
> +#include <linux/bitfield.h>
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/driver.h>
> +#include <linux/regulator/machine.h>
> +#include <linux/regulator/of_regulator.h>
> +#include <linux/util_macros.h>
> +
> +#define MAX77857_REG_INT_SRC		0x10
> +#define MAX77857_REG_INT_MASK		0x11
> +#define MAX77857_REG_CONT1		0x12
> +#define MAX77857_REG_CONT2		0x13
> +#define MAX77857_REG_CONT3		0x14
> +
> +#define MAX77857_INT_SRC_OCP		BIT(0)
> +#define MAX77857_INT_SRC_THS		BIT(1)
> +#define MAX77857_INT_SRC_HARDSHORT	BIT(2)
> +#define MAX77857_INT_SRC_OVP		BIT(3)
> +#define MAX77857_INT_SRC_POK		BIT(4)
> +
> +#define MAX77857_ILIM_MASK		GENMASK(2, 0)
> +#define MAX77857_CONT1_FREQ		GENMASK(4, 3)
> +#define MAX77857_CONT3_FPWM		BIT(5)
> +
> +#define MAX77859_REG_INT_SRC		0x11
> +#define MAX77859_REG_CONT1		0x13
> +#define MAX77859_REG_CONT2		0x14
> +#define MAX77859_REG_CONT3		0x15
> +#define MAX77859_REG_CONT5		0x17
> +#define MAX77859_CONT2_FPWM		BIT(2)
> +#define MAX77859_CONT2_INTB		BIT(3)
> +#define MAX77859_CONT3_DVS_START	BIT(2)
> +#define MAX77859_VOLTAGE_SEL_MASK	GENMASK(9, 0)
> +
> +#define MAX77859_CURRENT_MIN		1000000
> +#define MAX77859_CURRENT_MAX		5000000
> +#define MAX77859_CURRENT_STEP		50000
> +
> +enum max77857_id {
> +	ID_MAX77831 = 1,
> +	ID_MAX77857,
> +	ID_MAX77859,
> +	ID_MAX77859A,
> +};
> +
> +static bool max77857_volatile_reg(struct device *dev, unsigned int reg)
> +{
> +	enum max77857_id id = (enum max77857_id)dev_get_drvdata(dev);
> +
> +	switch (id) {
> +	case ID_MAX77831:
> +	case ID_MAX77857:
> +		return reg == MAX77857_REG_INT_SRC;
> +	case ID_MAX77859:
> +	case ID_MAX77859A:
> +		return reg == MAX77859_REG_INT_SRC;
> +	default:
> +		return true;
> +	}
> +}
> +
> +struct regmap_config max77857_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.cache_type = REGCACHE_MAPLE,
> +	.volatile_reg = max77857_volatile_reg,
> +};
> +
> +static int max77857_get_status(struct regulator_dev *rdev)
> +{
> +	unsigned int val;
> +	int ret;
> +
> +	ret = regmap_read(rdev->regmap, MAX77857_REG_INT_SRC, &val);
> +	if (ret)
> +		return ret;
> +
> +	if (FIELD_GET(MAX77857_INT_SRC_POK, val))
> +		return REGULATOR_STATUS_ON;
> +
> +	return REGULATOR_STATUS_ERROR;
> +}
> +
> +static unsigned int max77857_get_mode(struct regulator_dev *rdev)
> +{
> +	enum max77857_id id = (enum max77857_id)rdev_get_drvdata(rdev);
> +	unsigned int regval;
> +	int ret;
> +
> +	switch (id) {
> +	case ID_MAX77831:
> +	case ID_MAX77857:
> +		ret = regmap_read(rdev->regmap, MAX77857_REG_CONT3, &regval);
> +		if (ret)
> +			return ret;
> +
> +		if (FIELD_GET(MAX77857_CONT3_FPWM, regval))
> +			return REGULATOR_MODE_FAST;
> +
> +		break;
> +	case ID_MAX77859:
> +	case ID_MAX77859A:
> +		ret = regmap_read(rdev->regmap, MAX77859_REG_CONT2, &regval);
> +		if (ret)
> +			return ret;
> +
> +		if (FIELD_GET(MAX77859_CONT2_FPWM, regval))
> +			return REGULATOR_MODE_FAST;
> +
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	return REGULATOR_MODE_NORMAL;
> +}
> +
> +static int max77857_set_mode(struct regulator_dev *rdev, unsigned int mode)
> +{
> +	enum max77857_id id = (enum max77857_id)rdev_get_drvdata(rdev);
> +	unsigned int reg, val;
> +
> +	switch (id) {
> +	case ID_MAX77831:
> +	case ID_MAX77857:
> +		reg = MAX77857_REG_CONT3;
> +		val = MAX77857_CONT3_FPWM;
> +		break;
> +	case ID_MAX77859:
> +	case ID_MAX77859A:
> +		reg = MAX77859_REG_CONT2;
> +		val = MAX77859_CONT2_FPWM;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	switch (mode) {
> +	case REGULATOR_MODE_FAST:
> +		return regmap_set_bits(rdev->regmap, reg, val);
> +	case REGULATOR_MODE_NORMAL:
> +		return regmap_clear_bits(rdev->regmap, reg, val);
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int max77857_get_error_flags(struct regulator_dev *rdev,
> +				    unsigned int *flags)
> +{
> +	unsigned int val;
> +	int ret;
> +
> +	ret = regmap_read(rdev->regmap, MAX77857_REG_INT_SRC, &val);
> +	if (ret)
> +		return ret;
> +
> +	*flags = 0;
> +
> +	if (FIELD_GET(MAX77857_INT_SRC_OVP, val))
> +		*flags |= REGULATOR_ERROR_OVER_VOLTAGE_WARN;
> +
> +	if (FIELD_GET(MAX77857_INT_SRC_OCP, val) ||
> +	    FIELD_GET(MAX77857_INT_SRC_HARDSHORT, val))
> +		*flags |= REGULATOR_ERROR_OVER_CURRENT;
> +
> +	if (FIELD_GET(MAX77857_INT_SRC_THS, val))
> +		*flags |= REGULATOR_ERROR_OVER_TEMP;
> +
> +	if (!FIELD_GET(MAX77857_INT_SRC_POK, val))
> +		*flags |= REGULATOR_ERROR_FAIL;
> +
> +	return 0;
> +}
> +
> +static struct linear_range max77859_lin_ranges[] = {
> +	REGULATOR_LINEAR_RANGE(3200000, 0x0A0, 0x320, 20000)
> +};
> +
> +static const unsigned int max77859_ramp_table[4] = {
> +	1000, 500, 250, 125
> +};
> +
> +static int max77859_set_voltage_sel(struct regulator_dev *rdev,
> +				    unsigned int sel)
> +{
> +	__be16 reg;
> +	int ret;
> +
> +	reg = cpu_to_be16(sel);
> +
> +	ret = regmap_bulk_write(rdev->regmap, MAX77859_REG_CONT3, &reg, 2);
> +	if (ret)
> +		return ret;
> +
> +	/* actually apply new voltage */
> +	return regmap_set_bits(rdev->regmap, MAX77859_REG_CONT3,
> +			       MAX77859_CONT3_DVS_START);
> +}
> +
> +int max77859_get_voltage_sel(struct regulator_dev *rdev)
> +{
> +	__be16 reg;
> +	int ret;
> +
> +	ret = regmap_bulk_read(rdev->regmap, MAX77859_REG_CONT3, &reg, 2);
> +	if (ret)
> +		return ret;
> +
> +	return FIELD_GET(MAX77859_VOLTAGE_SEL_MASK, __be16_to_cpu(reg));
> +}
> +
> +int max77859_set_current_limit(struct regulator_dev *rdev, int min_uA, int max_uA)
> +{
> +	u32 selector;
> +
> +	if (max_uA < MAX77859_CURRENT_MIN)
> +		return -EINVAL;
> +
> +	selector = 0x12 + (max_uA - MAX77859_CURRENT_MIN) / MAX77859_CURRENT_STEP;
> +
> +	selector = clamp_val(selector, 0x00, 0x7F);
> +
> +	return regmap_write(rdev->regmap, MAX77859_REG_CONT5, selector);
> +}
> +
> +int max77859_get_current_limit(struct regulator_dev *rdev)
> +{
> +	u32 selector;
> +	int ret;
> +
> +	ret = regmap_read(rdev->regmap, MAX77859_REG_CONT5, &selector);
> +	if (ret)
> +		return ret;
> +
> +	if (selector <= 0x12)
> +		return MAX77859_CURRENT_MIN;
> +
> +	if (selector >= 0x64)
> +		return MAX77859_CURRENT_MAX;
> +
> +	return MAX77859_CURRENT_MIN + (selector - 0x12) * MAX77859_CURRENT_STEP;
> +}
> +
> +static const struct regulator_ops max77859_regulator_ops = {
> +	.list_voltage = regulator_list_voltage_linear_range,
> +	.set_voltage_sel = max77859_set_voltage_sel,
> +	.get_voltage_sel = max77859_get_voltage_sel,
> +	.set_ramp_delay = regulator_set_ramp_delay_regmap,
> +	.get_status = max77857_get_status,
> +	.set_mode = max77857_set_mode,
> +	.get_mode = max77857_get_mode,
> +	.get_error_flags = max77857_get_error_flags,
> +};
> +
> +static const struct regulator_ops max77859a_regulator_ops = {
> +	.list_voltage = regulator_list_voltage_linear_range,
> +	.set_voltage_sel = max77859_set_voltage_sel,
> +	.get_voltage_sel = max77859_get_voltage_sel,
> +	.set_current_limit = max77859_set_current_limit,
> +	.get_current_limit = max77859_get_current_limit,
> +	.set_ramp_delay = regulator_set_ramp_delay_regmap,
> +	.get_status = max77857_get_status,
> +	.set_mode = max77857_set_mode,
> +	.get_mode = max77857_get_mode,
> +	.get_error_flags = max77857_get_error_flags,
> +};
> +
> +static const struct regulator_ops max77857_regulator_ops = {
> +	.list_voltage = regulator_list_voltage_linear_range,
> +	.set_voltage_sel = regulator_set_voltage_sel_regmap,
> +	.get_voltage_sel = regulator_get_voltage_sel_regmap,
> +	.set_ramp_delay = regulator_set_ramp_delay_regmap,
> +	.get_status = max77857_get_status,
> +	.set_mode = max77857_set_mode,
> +	.get_mode = max77857_get_mode,
> +	.get_error_flags = max77857_get_error_flags,
> +};
> +
> +static struct linear_range max77857_lin_ranges[] = {
> +	REGULATOR_LINEAR_RANGE(4485000, 0x3D, 0xCC, 73500)
> +};
> +
> +static const unsigned int max77857_switch_freq[] = {
> +	1200000, 1500000, 1800000, 2100000
> +};
> +
> +static const unsigned int max77857_ramp_table[2][4] = {
> +	{ 1333, 667, 333, 227 }, /* when switch freq is 1.8MHz or 2.1MHz */
> +	{ 1166, 667, 333, 167 }, /* when switch freq is 1.2MHz or 1.5MHz */
> +};
> +
> +static struct regulator_desc max77857_regulator_desc = {
> +	.ops = &max77857_regulator_ops,
> +	.name = "max77857",
> +	.linear_ranges = max77857_lin_ranges,
> +	.n_linear_ranges = ARRAY_SIZE(max77857_lin_ranges),
> +	.vsel_mask = 0xFF,
> +	.vsel_reg = MAX77857_REG_CONT2,
> +	.ramp_delay_table = max77857_ramp_table[0],
> +	.n_ramp_values = ARRAY_SIZE(max77857_ramp_table[0]),
> +	.ramp_reg = MAX77857_REG_CONT3,
> +	.ramp_mask = GENMASK(1, 0),
> +	.ramp_delay = max77857_ramp_table[0][0],

This breaks the build with GCC 5.x through 7.x:

  drivers/regulator/max77857-regulator.c:312:16: error: initializer element is not constant
    .ramp_delay = max77857_ramp_table[0][0],
                  ^~~~~~~~~~~~~~~~~~~
  drivers/regulator/max77857-regulator.c:312:16: note: (near initialization for 'max77857_regulator_desc.ramp_delay')

and clang:

  drivers/regulator/max77857-regulator.c:312:16: error: initializer element is not a compile-time constant
    312 |         .ramp_delay = max77857_ramp_table[0][0],
        |                       ^~~~~~~~~~~~~~~~~~~~~~~~~
  1 error generated.

This relies on a GCC 8.x+ change that accepts more things as
compile-time constants, which is being worked on in clang
(https://reviews.llvm.org/D76096). Since the kernel supports older
compilers, this will have to be worked around somehow. Perhaps a define
that can be used in both places?

Cheers,
Nathan

> +	.owner = THIS_MODULE,
> +};
> +
> +static void max77857_calc_range(struct device *dev, enum max77857_id id)
> +{
> +	struct linear_range *range;
> +	unsigned long vref_step;
> +	u32 rtop = 0;
> +	u32 rbot = 0;
> +
> +	device_property_read_u32(dev, "adi,rtop-ohms", &rtop);
> +	device_property_read_u32(dev, "adi,rbot-ohms", &rbot);
> +
> +	if (!rbot || !rtop)
> +		return;
> +
> +	switch (id) {
> +	case ID_MAX77831:
> +	case ID_MAX77857:
> +		range = max77857_lin_ranges;
> +		vref_step = 4900UL;
> +		break;
> +	case ID_MAX77859:
> +	case ID_MAX77859A:
> +		range = max77859_lin_ranges;
> +		vref_step = 1250UL;
> +		break;
> +	}
> +
> +	range->step = DIV_ROUND_CLOSEST(vref_step * (rbot + rtop), rbot);
> +	range->min = range->step * range->min_sel;
> +}
> +
> +static int max77857_probe(struct i2c_client *client)
> +{
> +	const struct i2c_device_id *i2c_id;
> +	struct device *dev = &client->dev;
> +	struct regulator_config cfg = { };
> +	struct regulator_dev *rdev;
> +	struct regmap *regmap;
> +	enum max77857_id id;
> +	u32 switch_freq = 0;
> +	int ret;
> +
> +	i2c_id = i2c_client_get_device_id(client);
> +	if (!i2c_id)
> +		return -EINVAL;
> +
> +	id = i2c_id->driver_data;
> +
> +	dev_set_drvdata(dev, (void *)id);
> +
> +	if (id == ID_MAX77859 || id == ID_MAX77859A) {
> +		max77857_regulator_desc.ops = &max77859_regulator_ops;
> +		max77857_regulator_desc.linear_ranges = max77859_lin_ranges;
> +		max77857_regulator_desc.ramp_delay_table = max77859_ramp_table;
> +		max77857_regulator_desc.ramp_delay = max77859_ramp_table[0];
> +	}
> +
> +	if (id == ID_MAX77859A)
> +		max77857_regulator_desc.ops = &max77859a_regulator_ops;
> +
> +	max77857_calc_range(dev, id);
> +
> +	regmap = devm_regmap_init_i2c(client, &max77857_regmap_config);
> +	if (IS_ERR(regmap))
> +		return dev_err_probe(dev, PTR_ERR(regmap),
> +				     "cannot initialize regmap\n");
> +
> +	device_property_read_u32(dev, "adi,switch-frequency-hz", &switch_freq);
> +	if (switch_freq) {
> +		switch_freq = find_closest(switch_freq, max77857_switch_freq,
> +					   ARRAY_SIZE(max77857_switch_freq));
> +
> +		if (id == ID_MAX77831 && switch_freq == 3)
> +			switch_freq = 2;
> +
> +		switch (id) {
> +		case ID_MAX77831:
> +		case ID_MAX77857:
> +			ret = regmap_update_bits(regmap, MAX77857_REG_CONT1,
> +						 MAX77857_CONT1_FREQ, switch_freq);
> +
> +			if (switch_freq >= 2)
> +				break;
> +
> +			max77857_regulator_desc.ramp_delay_table = max77857_ramp_table[1];
> +			max77857_regulator_desc.ramp_delay = max77857_ramp_table[1][0];
> +			break;
> +		case ID_MAX77859:
> +		case ID_MAX77859A:
> +			ret = regmap_update_bits(regmap, MAX77859_REG_CONT1,
> +						 MAX77857_CONT1_FREQ, switch_freq);
> +			break;
> +		}
> +		if (ret)
> +			return ret;
> +	}
> +
> +	cfg.dev = dev;
> +	cfg.driver_data = (void *)id;
> +	cfg.regmap = regmap;
> +	cfg.init_data = of_get_regulator_init_data(dev, dev->of_node,
> +						   &max77857_regulator_desc);
> +	if (!cfg.init_data)
> +		return -ENOMEM;
> +
> +	rdev = devm_regulator_register(dev, &max77857_regulator_desc, &cfg);
> +	if (IS_ERR(rdev))
> +		return dev_err_probe(dev, PTR_ERR(rdev),
> +				     "cannot register regulator\n");
> +
> +	return 0;
> +}
> +
> +const struct i2c_device_id max77857_id[] = {
> +	{ "max77831", ID_MAX77831 },
> +	{ "max77857", ID_MAX77857 },
> +	{ "max77859", ID_MAX77859 },
> +	{ "max77859a", ID_MAX77859A },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, max77857_id);
> +
> +static const struct of_device_id max77857_of_id[] = {
> +	{ .compatible = "adi,max77831", .data = (void *)ID_MAX77831 },
> +	{ .compatible = "adi,max77857", .data = (void *)ID_MAX77857 },
> +	{ .compatible = "adi,max77859", .data = (void *)ID_MAX77859 },
> +	{ .compatible = "adi,max77859a", .data = (void *)ID_MAX77859A },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, max77857_of_id);
> +
> +struct i2c_driver max77857_driver = {
> +	.driver = {
> +		.name = "max77857",
> +		.of_match_table = max77857_of_id,
> +	},
> +	.id_table = max77857_id,
> +	.probe_new = max77857_probe,
> +};
> +module_i2c_driver(max77857_driver);
> +
> +MODULE_DESCRIPTION("Analog Devices MAX77857 Buck-Boost Converter Driver");
> +MODULE_AUTHOR("Ibrahim Tilki <Ibrahim.Tilki@analog.com>");
> +MODULE_AUTHOR("Okan Sahin <Okan.Sahin@analog.com>");
> +MODULE_LICENSE("GPL");
> -- 
> 2.30.2
>