Re: [PATCH v8 2/2] mfd: max597x: Add support for MAX5970 and MAX5978

[Lee Jones <lee@kernel.org>]

On Thu, 03 Nov 2022, Naresh Solanki wrote:

> From: Patrick Rudolph <patrick.rudolph@9elements.com>
> 
> Implement a regulator driver with IRQ support for fault management.

This is not a "regulator driver".

> Written against documentation [1] and [2] and tested on real hardware.
> 
> Every channel has its own regulator supplies nammed 'vss1-supply' and
> 'vss2-supply'. The regulator supply is used to determine the output
> voltage, as the smart switch provides no output regulation.
> The driver requires the 'shunt-resistor-micro-ohms' property to be
> present in Device Tree to properly calculate current related
> values.
> 
> Datasheet links:
> 1: https://datasheets.maximintegrated.com/en/ds/MAX5970.pdf
> 2: https://datasheets.maximintegrated.com/en/ds/MAX5978.pdf
> 
> Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
> Signed-off-by: Marcello Sylvester Bauer <sylv@sylv.io>
> Signed-off-by: Naresh Solanki <Naresh.Solanki@9elements.com>

Can you explain these tags to me please?

Patrick wrote it.  Then what happened?

> ---
>  drivers/mfd/Kconfig         |  12 +++++
>  drivers/mfd/Makefile        |   1 +
>  drivers/mfd/max597x.c       |  92 ++++++++++++++++++++++++++++++++
>  include/linux/mfd/max597x.h | 103 ++++++++++++++++++++++++++++++++++++
>  4 files changed, 208 insertions(+)
>  create mode 100644 drivers/mfd/max597x.c
>  create mode 100644 include/linux/mfd/max597x.h
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 8b93856de432..416fe7986b7b 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -253,6 +253,18 @@ config MFD_MADERA_SPI
>  	  Support for the Cirrus Logic Madera platform audio SoC
>  	  core functionality controlled via SPI.
>  
> +config MFD_MAX597X
> +	tristate "Maxim 597x Power Switch and Monitor"
> +	depends on I2C
> +	depends on OF
> +	select MFD_CORE
> +	select REGMAP_I2C
> +	help
> +	  This driver controls a Maxim 5970/5978 switch via I2C bus.
> +	  The MAX5970/5978 is a smart switch with no output regulation, but
> +	  fault protection and voltage and current monitoring capabilities.
> +	  Also it supports upto 4 indication LEDs.
> +
>  config MFD_CS47L15
>  	bool "Cirrus Logic CS47L15"
>  	select PINCTRL_CS47L15
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 7ed3ef4a698c..819d711fa748 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -161,6 +161,7 @@ obj-$(CONFIG_MFD_DA9063)	+= da9063.o
>  obj-$(CONFIG_MFD_DA9150)	+= da9150-core.o
>  
>  obj-$(CONFIG_MFD_MAX14577)	+= max14577.o
> +obj-$(CONFIG_MFD_MAX597X)	+= max597x.o
>  obj-$(CONFIG_MFD_MAX77620)	+= max77620.o
>  obj-$(CONFIG_MFD_MAX77650)	+= max77650.o
>  obj-$(CONFIG_MFD_MAX77686)	+= max77686.o
> diff --git a/drivers/mfd/max597x.c b/drivers/mfd/max597x.c
> new file mode 100644
> index 000000000000..2c64edb6b6dd
> --- /dev/null
> +++ b/drivers/mfd/max597x.c
> @@ -0,0 +1,92 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Maxim MAX5970/MAX5978 MFD Driver

Please drop "MFD Driver" and replace it with what it does.

"Power Switch and Monitor"?

> + * Copyright (c) 2022 9elements GmbH
> + *
> + * Author: Patrick Rudolph <patrick.rudolph@9elements.com>
> + */
> +
> +#include <linux/i2c.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/max597x.h>
> +#include <linux/regmap.h>
> +
> +static const struct regmap_config max597x_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.max_register = MAX_REGISTERS,
> +};
> +
> +static const struct mfd_cell max597x_cells[] = {
> +	{ .name = "max597x-regulator", },
> +	{ .name = "max597x-iio", },
> +	{ .name = "max597x-led", },
> +};
> +
> +static int max597x_probe(struct i2c_client *i2c, const struct i2c_device_id *id)
> +{
> +	struct max597x_data *ddata;
> +	enum max597x_chip_type chip = id->driver_data;
> +
> +	ddata = devm_kzalloc(&i2c->dev, sizeof(*ddata),	GFP_KERNEL);
> +	if (!ddata)
> +		return -ENOMEM;
> +
> +	/* Initialize num of switch based on chip type for later use by regulator
> +	 * & iio cells
> +	 */

Please use proper multi-line comment structure.

Also use proper words, unlike 'num'.

In fact, it looks like this whole comment could do with some love.

> +	switch (chip) {
> +	case MAX597x_TYPE_MAX5970:
> +		ddata->num_switches = MAX5970_NUM_SWITCHES;
> +		break;
> +	case MAX597x_TYPE_MAX5978:
> +		ddata->num_switches = MAX5978_NUM_SWITCHES;
> +		break;
> +	}
> +
> +	ddata->regmap = devm_regmap_init_i2c(i2c, &max597x_regmap_config);
> +	if (IS_ERR(ddata->regmap)) {
> +		dev_err(&i2c->dev, "Failed to initialise regmap");

Are you using American spelling or English?

Please make up your mind and be consistent.

> +		return -EINVAL;

Shouldn't you be propagating the error you received?

> +	}
> +
> +	/* IRQ used by regulator cell */

What IRQ is this?  Does it have a name?

If it's only used in Regulator, why not fetch it there?

> +	ddata->irq = i2c->irq;
> +	ddata->dev = &i2c->dev;

You should already have access to the Driver, else how are you going
to fetch the data back in the first place?

> +	i2c_set_clientdata(i2c, ddata);
> +
> +	return devm_mfd_add_devices(ddata->dev, PLATFORM_DEVID_AUTO,
> +				    max597x_cells, ARRAY_SIZE(max597x_cells),
> +				    NULL, 0, NULL);
> +}
> +
> +static const struct i2c_device_id max597x_table[] = {
> +	{ .name = "max5970", MAX597x_TYPE_MAX5970 },
> +	{ .name = "max5978", MAX597x_TYPE_MAX5978 },

You don't need ".name = ".

> +};
> +
> +MODULE_DEVICE_TABLE(i2c, max597x_table);
> +
> +static const struct of_device_id max597x_of_match[] = {
> +	{ .compatible = "maxim,max5970", .data = (void *)MAX597x_TYPE_MAX5970 },
> +	{ .compatible = "maxim,max5978", .data = (void *)MAX597x_TYPE_MAX5978 },

Where is .data used?

> +	{ /* sentinel */ }

Drop the comment.  We know what a NULL entry means.

> +};
> +
> +MODULE_DEVICE_TABLE(of, max597x_of_match);
> +
> +static struct i2c_driver max597x_driver = {
> +	.id_table = max597x_table,
> +	.driver = {
> +		.name = "max597x",
> +		.of_match_table = of_match_ptr(max597x_of_match),
> +		},

Tabbing error.

> +	.probe = max597x_probe,
> +};
> +

Remove this line.

> +module_i2c_driver(max597x_driver);
> +
> +MODULE_AUTHOR("Patrick Rudolph <patrick.rudolph@9elements.com>");
> +MODULE_DESCRIPTION("MAX597X Power Switch and Monitor");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/mfd/max597x.h b/include/linux/mfd/max597x.h
> new file mode 100644
> index 000000000000..f88a57f0e4f2
> --- /dev/null
> +++ b/include/linux/mfd/max597x.h
> @@ -0,0 +1,103 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Maxim MAX5970/MAX5978 MFD Driver

Same here.

> + * Copyright (c) 2022 9elements GmbH
> + *
> + * Author: Patrick Rudolph <patrick.rudolph@9elements.com>
> + */
> +
> +#ifndef MFD_MAX597X_H
> +#define MFD_MAX597X_H
> +
> +#include <linux/device.h>
> +#include <linux/regmap.h>
> +
> +/* Number of switch based on chip variant */

This comment is superfluous.

> +#define MAX5970_NUM_SWITCHES 2
> +#define MAX5978_NUM_SWITCHES 1
> +/* Both chip variant have 4 indication LEDs used by LED cell */

Here too I think.

> +#define MAX597X_NUM_LEDS     4
> +
> +enum max597x_chip_type {
> +	MAX597x_TYPE_MAX5978 = 1,

Why 1?

> +	MAX597x_TYPE_MAX5970,
> +};
> +
> +#define MAX5970_REG_CURRENT_L(ch)		(0x01 + (ch) * 4)
> +#define MAX5970_REG_CURRENT_H(ch)		(0x00 + (ch) * 4)
> +#define MAX5970_REG_VOLTAGE_L(ch)		(0x03 + (ch) * 4)
> +#define MAX5970_REG_VOLTAGE_H(ch)		(0x02 + (ch) * 4)
> +#define MAX5970_REG_MON_RANGE			0x18
> +#define  MAX5970_MON_MASK				0x3
> +#define  MAX5970_MON(reg, ch)		(((reg) >> ((ch) * 2)) & MAX5970_MON_MASK)
> +#define  MAX5970_MON_MAX_RANGE_UV		16000000
> +
> +#define MAX5970_REG_CH_UV_WARN_H(ch)	(0x1A + (ch) * 10)
> +#define MAX5970_REG_CH_UV_WARN_L(ch)	(0x1B + (ch) * 10)
> +#define MAX5970_REG_CH_UV_CRIT_H(ch)	(0x1C + (ch) * 10)
> +#define MAX5970_REG_CH_UV_CRIT_L(ch)	(0x1D + (ch) * 10)
> +#define MAX5970_REG_CH_OV_WARN_H(ch)	(0x1E + (ch) * 10)
> +#define MAX5970_REG_CH_OV_WARN_L(ch)	(0x1F + (ch) * 10)
> +#define MAX5970_REG_CH_OV_CRIT_H(ch)	(0x20 + (ch) * 10)
> +#define MAX5970_REG_CH_OV_CRIT_L(ch)	(0x21 + (ch) * 10)
> +
> +#define  MAX5970_VAL2REG_H(x)			(((x) >> 2) & 0xFF)
> +#define  MAX5970_VAL2REG_L(x)			((x) & 0x3)
> +
> +#define MAX5970_REG_DAC_FAST(ch)		(0x2E + (ch))
> +
> +#define MAX5970_FAST2SLOW_RATIO			200
> +
> +#define MAX5970_REG_STATUS0				0x31
> +#define  MAX5970_CB_IFAULTF(ch)			(1 << (ch))
> +#define  MAX5970_CB_IFAULTS(ch)			(1 << ((ch) + 4))
> +
> +#define MAX5970_REG_STATUS1				0x32
> +#define  STATUS1_PROT_MASK				0x3
> +#define  STATUS1_PROT(reg) \
> +	(((reg) >> 6) & STATUS1_PROT_MASK)
> +#define  STATUS1_PROT_SHUTDOWN			0
> +#define  STATUS1_PROT_CLEAR_PG			1
> +#define  STATUS1_PROT_ALERT_ONLY		2
> +
> +#define MAX5970_REG_STATUS2				0x33
> +#define  MAX5970_IRNG_MASK				0x3
> +#define  MAX5970_IRNG(reg, ch)	\
> +						(((reg) >> ((ch) * 2)) & MAX5970_IRNG_MASK)
> +
> +#define MAX5970_REG_STATUS3				0x34
> +#define  MAX5970_STATUS3_ALERT			BIT(4)
> +#define  MAX5970_STATUS3_PG(ch)			BIT(ch)
> +
> +#define MAX5970_REG_FAULT0				0x35
> +#define  UV_STATUS_WARN(ch)				BIT(ch)
> +#define  UV_STATUS_CRIT(ch)				BIT(ch + 4)
> +
> +#define MAX5970_REG_FAULT1				0x36
> +#define  OV_STATUS_WARN(ch)				BIT(ch)
> +#define  OV_STATUS_CRIT(ch)				BIT(ch + 4)
> +
> +#define MAX5970_REG_FAULT2				0x37
> +#define  OC_STATUS_WARN(ch)				BIT(ch)
> +
> +#define MAX5970_REG_CHXEN				0x3b
> +#define  CHXEN(ch)						(3 << (ch * 2))
> +
> +#define MAX5970_REG_LED_FLASH			0x43

Do these all need to be shared?

Or can they be isolated into, say, the Regulator driver?

> +#define MAX_REGISTERS					0x49
> +#define ADC_MASK						0x3FF
> +
> +struct max597x_data {
> +	struct device *dev;
> +	int irq;
> +	int num_switches;
> +	struct regmap *regmap;
> +	/* Chip specific parameters needed by regulator & iio cells */
> +	u32 irng[MAX5970_NUM_SWITCHES];
> +	u32 mon_rng[MAX5970_NUM_SWITCHES];
> +	u32 shunt_micro_ohms[MAX5970_NUM_SWITCHES];
> +};
> +
> +#endif				/* _MAX597X_H */

                                       This is incorrect and doesn't
				       need to be tabbed out over
				       here.

-- 
Lee Jones [李琼斯]