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SubjectRe: [PATCH v8 2/2] mfd: max597x: Add support for MAX5970 and MAX5978
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Hi Lee

On 07-11-2022 03:06 pm, Lee Jones wrote:
> 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?
>
Yes Its written by Patrick & Marcello.
>> ---
>> 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"?
>
Yes. that makes more sense. sure.
>> + * 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.
>
Done.
>> + 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.
>
Sure
>> + return -EINVAL;
>
> Shouldn't you be propagating the error you received?
>
Yes. Will update in next version.
>> + }
>> +
>> + /* IRQ used by regulator cell */
>
> What IRQ is this? Does it have a name?
>Its is VR fault status update related irq.
> 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?
The .data isn't used.
>
>> + { /* sentinel */ }
> > Drop the comment. We know what a NULL entry means.
Sure.
>
>> +};
>> +
>> +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.
Fixed Will be in next version.
>
>> + .probe = max597x_probe,
>> +};
>> +
>
> Remove this line.
Sure.
>
>> +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.
You mean this comment should be removed ?
>
>> +#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?
MAX5978 & single power switch wheres MAX5970 has two.
>
>> + 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?
>
Shared reg.
>> +#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.
>
Will update in next version.

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