Message-ID: <20220713141616.GA3823727@roeck-us.net>
Date:   Wed, 13 Jul 2022 07:16:16 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Atif Ofluoglu <Atif.Ofluoglu@...log.com>
Cc:     jdelvare@...e.com, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] hwmon: (pmbus/max20754) Add support for MAX20754

On Thu, Jul 07, 2022 at 03:29:17PM +0000, Atif Ofluoglu wrote:
> From: Atif Ofluoglu <atif.ofluoglu@...log.com>
> 
> Signed-off-by: Atif Ofluoglu <Atif.Ofluoglu@...log.com>

Please use lowercase for the e-mail address to avoid confusing
checkpatch.

> ---
>  drivers/hwmon/pmbus/Kconfig    |   9 +
>  drivers/hwmon/pmbus/Makefile   |   1 +
>  drivers/hwmon/pmbus/max20754.c | 390 +++++++++++++++++++++++++++++++++
>  3 files changed, 400 insertions(+)
>  create mode 100644 drivers/hwmon/pmbus/max20754.c
> 
> diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
> index dfae76db65ae..f259b8739766 100644
> --- a/drivers/hwmon/pmbus/Kconfig
> +++ b/drivers/hwmon/pmbus/Kconfig
> @@ -254,6 +254,15 @@ config SENSORS_MAX20751
>  	  This driver can also be built as a module. If so, the module will
>  	  be called max20751.
>  
> +config SENSORS_MAX20754
> +	tristate "Maxim MAX20754"
> +	help
> +	  If you say yes here you get hardware monitoring support for Maxim
> +	  MAX20754.
> +
> +	  This driver can also be built as a module. If so, the module will
> +	  be called max20754.
> +
>  config SENSORS_MAX31785
>  	tristate "Maxim MAX31785 and compatibles"
>  	help
> diff --git a/drivers/hwmon/pmbus/Makefile b/drivers/hwmon/pmbus/Makefile
> index 4678fba5012c..b8b1d8a84b3b 100644
> --- a/drivers/hwmon/pmbus/Makefile
> +++ b/drivers/hwmon/pmbus/Makefile
> @@ -27,6 +27,7 @@ obj-$(CONFIG_SENSORS_MAX16064)	+= max16064.o
>  obj-$(CONFIG_SENSORS_MAX16601)	+= max16601.o
>  obj-$(CONFIG_SENSORS_MAX20730)	+= max20730.o
>  obj-$(CONFIG_SENSORS_MAX20751)	+= max20751.o
> +obj-$(CONFIG_SENSORS_MAX20751)	+= max20754.o
>  obj-$(CONFIG_SENSORS_MAX31785)	+= max31785.o
>  obj-$(CONFIG_SENSORS_MAX34440)	+= max34440.o
>  obj-$(CONFIG_SENSORS_MAX8688)	+= max8688.o
> diff --git a/drivers/hwmon/pmbus/max20754.c b/drivers/hwmon/pmbus/max20754.c
> new file mode 100644
> index 000000000000..5e29e8f8009b
> --- /dev/null
> +++ b/drivers/hwmon/pmbus/max20754.c
> @@ -0,0 +1,390 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Maxim MAX20754 Dual-Output, Configurable Multiphase
> + * Power-Supply Controller with PMBus Interface
> + * and Internal Buck Converter Driver
> + *
> + * Author: Atif Emre Ofluoglu <atif.ofluoglu@...log.com>
> + * Copyright (C) 2022 Analog Devices
> + *
> + * 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.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/hwmon.h>

Alphabetic include file order, please.

> +#include <linux/hwmon-sysfs.h>

Not needed.

> +#include "pmbus.h"
> +
> +enum chips { max20754 };

Not needed unless you plan to add another chip to the driver later on,
and then it should be added with the patch introducing that chip.

> +
> +#define MAX20754_NUM_PHASES 6
> +#define MAX20754_LINEAR_EXPONENT -10

#define<space>NAME<tab>value, please. Also, (-10)

> +
> +struct max20754_data {
> +	enum chips id;
> +	struct pmbus_driver_info info;
> +	struct i2c_client *rail2;
> +	bool smbus_i2c_block_read;
> +};
> +
> +#define to_max20754_data(x) container_of(x, struct max20754_data, info)
> +
> +enum max20754_reg_index {
> +	operation_index,
> +	on_off_config_index,
> +	vout_command_index,
> +	num_regs,
> +};
> +
> +static const u8 max20754_regs[num_regs][2] = {
> +	[operation_index] = {PMBUS_OPERATION, 1},
> +	[on_off_config_index] = {PMBUS_ON_OFF_CONFIG, 1},
> +	[vout_command_index] = {PMBUS_VOUT_COMMAND, 2},
> +};
> +
> +static u16 val_to_linear16(int val)
> +{
> +	return ((u16)val * 1000LL) >> -MAX20754_LINEAR_EXPONENT;

Double negation whenever MAX20754_LINEAR_EXPONENT ? What is the point
of that ?

> +}
> +
> +static long linear16_to_val(s64 val)
> +{
> +	if (val == 0)
> +		return 0;

Why is that needed ?

> +
> +	val <<= -MAX20754_LINEAR_EXPONENT;
> +	val = DIV_ROUND_CLOSEST_ULL(val, 1000);
> +	val = clamp_val(val, 0, 0xffff);
> +	return val;
> +}
> +
> +static int max20754_read_block_data(struct i2c_client *client, int reg,
> +				    u8 length, u8 *values)
> +{
> +	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
> +	struct max20754_data *data = to_max20754_data(info);
> +	int ret;
> +
> +	if (data->smbus_i2c_block_read) {
> +		ret = i2c_smbus_read_i2c_block_data(client, reg, length, values);
> +		if (ret < 1)
> +			return ret;
> +		ret = ret - 1;
> +		memcpy(values, &values[1], ret);
> +	} else {
> +		ret = i2c_smbus_read_block_data(client, reg, values);
> +	}
> +
> +	return ret;
> +}
> +
> +static int max20754_read_word(struct i2c_client *client, int page, int phase,
> +			      int reg)
> +{
> +	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
> +	struct max20754_data *data = to_max20754_data(info);
> +
> +	if (reg > 0xFF)
> +		return -ENXIO;
> +
> +	if (reg == PMBUS_MFR_VOUT_MAX)
> +		reg = PMBUS_VOUT_MAX;
> +

I don't think this makes sense. MFR_VOUT_MAX is the _rated_
maximum output voltage, while VOUT_MAX is the _configured_ maximum
output voltage. Those are distinctly diffferent.

> +	switch (page) {
> +	case 0:		/* RAIL1 */
> +		return i2c_smbus_read_word_data(client, reg);
> +	case 1:		/* RAIL2 */
> +		return i2c_smbus_read_word_data(data->rail2, reg);
> +	default:
> +		return -ENODATA;
> +	}
> +
> +	return -ENODATA;
> +}
> +
> +static int max20754_write_word(struct i2c_client *client, int page, int reg, u16 value)
> +{
> +	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
> +	struct max20754_data *data = to_max20754_data(info);
> +
> +	switch (reg) {
> +	case PMBUS_OPERATION:
> +		if (value >= 0x90 && value <= 0x93)
> +			return -EOPNOTSUPP;
> +		break;
> +	case PMBUS_MFR_VOUT_MAX:
> +		reg = PMBUS_VOUT_MAX;
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	switch (page) {
> +	case 0:		/* RAIL1 */
> +		return i2c_smbus_write_word_data(client, reg, value);
> +	case 1:		/* RAIL2 */
> +		return i2c_smbus_write_word_data(data->rail2, reg, value);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +	return -ENODATA;
> +}
> +
> +static int max20754_read_byte(struct i2c_client *client, int page, int reg)
> +{
> +	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
> +	struct max20754_data *data = to_max20754_data(info);
> +	int vout_mode;
> +
> +	if (reg == PMBUS_VOUT_MODE) {
> +		vout_mode = i2c_smbus_read_byte_data(client, reg);
> +		if (vout_mode != 0x2C)
> +			vout_mode = 0x16;

This ignores errors.

> +		return vout_mode;

Needs explanation.

> +	}
> +
> +	switch (page) {
> +	case 0:		/* RAIL1 */
> +		return i2c_smbus_read_byte_data(client, reg);
> +	case 1:		/* RAIL2 */
> +		return i2c_smbus_read_byte_data(data->rail2, reg);
> +	default:
> +		return -ENODATA;
> +	}
> +	return -ENODATA;
> +}
> +
> +static int max20754_write_byte(struct i2c_client *client, int page, u8 reg)
> +{
> +	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
> +	struct max20754_data *data = to_max20754_data(info);
> +
> +	if (reg == PMBUS_CLEAR_FAULTS) {
> +		switch (page) {
> +		case 0:
> +			return i2c_smbus_write_byte(client, reg);
> +		case 1:
> +			return i2c_smbus_write_byte(data->rail2, reg);
> +		default:
> +			return -ENODATA;
> +		}
> +	}
> +	return -ENODATA;
> +}
> +
> +static int max20754_identify(struct i2c_client *client,
> +			     struct pmbus_driver_info *info)
> +{
> +	struct device *dev = &client->dev;
> +	u8 buf[9] = {0};
> +	int ret;
> +
> +	ret = max20754_read_block_data(client,
> +				       PMBUS_IC_DEVICE_ID, 9,
> +				       buf);
> +
> +	if (ret < 0 || ret < 8)
> +		return -ENODEV;
> +
> +	/*
> +	 * PMBUS_IC_DEVICE_ID is expected to return "MAX20754"
> +	 */
> +
> +	if (strncmp(buf, "MAX20754", 8)) {
> +		buf[ret] = '\0';
> +		dev_err(dev, "Unsupported chip '%s'\n", buf);
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}

The above can and should be handled in the probe function.
With this, the smbus_i2c_block_read boolean in struct max20754_data
is no longer necessary. 

> +
> +static ssize_t max20754_register_store(struct device *dev,
> +				       struct device_attribute *attr, const char *buf,
> +				       size_t count)
> +{
> +	struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
> +	struct i2c_client *client = to_i2c_client(dev->parent);
> +	const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
> +	struct max20754_data *data = to_max20754_data(info);
> +
> +	u8 cmd = max20754_regs[sattr->index][0];
> +	u8 reg_size = max20754_regs[sattr->index][1];
> +	u8 rail_number = sattr->nr;
> +	long val = 0;

Unnecessary initialization.

> +	int ret;
> +
> +	ret = kstrtol(buf, 10, &val);
> +	if (ret)
> +		return ret;
> +
> +	if (rail_number == 1)
> +		client = data->rail2;
> +
> +	if (cmd == PMBUS_VOUT_COMMAND)
> +		val = linear16_to_val(val);
> +
> +	switch (reg_size) {
> +	case 1:
> +		ret = i2c_smbus_write_byte_data(client, cmd, val);
> +		break;
> +	case 2:
> +		ret = i2c_smbus_write_word_data(client, cmd, val);
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	if (ret < 0)
> +		return ret;
> +
> +	return count;
> +}
> +
> +static ssize_t max20754_register_show(struct device *dev,
> +				      struct device_attribute *attr, char *buf)
> +{
> +	struct sensor_device_attribute_2 *sattr = to_sensor_dev_attr_2(attr);
> +	struct i2c_client *client = to_i2c_client(dev->parent);
> +
> +	int ret_val = 0;

Why ret_val instead of ret like everywhere else ?

> +	u8 cmd = max20754_regs[sattr->index][0];
> +	u8 reg_size = max20754_regs[sattr->index][1];
> +	u8 rail_number = sattr->nr;
> +
> +	switch (reg_size) {
> +	case 1:
> +		ret_val = max20754_read_byte(client, rail_number, cmd);
> +		break;
> +	case 2:
> +		ret_val = max20754_read_word(client, rail_number, 0, cmd);
> +		break;
> +	default:
> +		break;
> +	}
> +
> +	if (ret_val < 0)
> +		return -ENODATA;
> +
> +	if (cmd == PMBUS_VOUT_COMMAND)
> +		ret_val = val_to_linear16(ret_val);
> +
> +	return sprintf(buf, "%d\n", ret_val);
> +}
> +
> +#define MAX20754_REGISTER_ATTR_RW(__name, __reg_index, __size) \
> +	SENSOR_DEVICE_ATTR_2_RW(__name, max20754_register, __size, __reg_index)
> +
> +static MAX20754_REGISTER_ATTR_RW(operation, operation_index, 0);
> +static MAX20754_REGISTER_ATTR_RW(on_off_config, on_off_config_index, 0);
> +
> +static MAX20754_REGISTER_ATTR_RW(vout1_command, vout_command_index, 0);
> +static MAX20754_REGISTER_ATTR_RW(vout2_command, vout_command_index, 1);
> +

The above attributes are not acceptable. Register as regulator(s) if you
want to control output voltage and operation.

> +static struct attribute *max20754_attrs[] = {
> +	&sensor_dev_attr_operation.dev_attr.attr,
> +	&sensor_dev_attr_on_off_config.dev_attr.attr,
> +	&sensor_dev_attr_vout1_command.dev_attr.attr,
> +	&sensor_dev_attr_vout2_command.dev_attr.attr,
> +	NULL
> +};
> +ATTRIBUTE_GROUPS(max20754);
> +
> +static struct pmbus_driver_info max20754_info = {
> +	.pages = 2,
> +	.format[PSC_VOLTAGE_IN] = linear,
> +	.format[PSC_VOLTAGE_OUT] = linear,
> +	.vrm_version[0] = vr12,
> +	.format[PSC_TEMPERATURE] = linear,
> +	.format[PSC_CURRENT_OUT] = linear,
> +	.format[PSC_POWER] = linear,
> +	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT |
> +		PMBUS_HAVE_STATUS_INPUT | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
> +		PMBUS_HAVE_TEMP | PMBUS_HAVE_TEMP2 | PMBUS_HAVE_STATUS_TEMP,
> +	.func[1] = PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_VOUT | PMBUS_HAVE_STATUS_INPUT |
> +		PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT |
> +		PMBUS_HAVE_TEMP2 | PMBUS_HAVE_STATUS_TEMP,
> +	.identify = max20754_identify,
> +	.read_byte_data = max20754_read_byte,
> +	.read_word_data = max20754_read_word,
> +	.write_byte = max20754_write_byte,
> +	.write_word_data = max20754_write_word,
> +};
> +
> +static void max20754_remove(void *_data)
> +{
> +	struct max20754_data *data = _data;
> +
> +	i2c_unregister_device(data->rail2);
> +}
> +
> +static int max20754_probe(struct i2c_client *client)
> +{
> +	struct device *dev = &client->dev;
> +	struct max20754_data *data;
> +	bool i2c_block_data_ok = false;
> +	int ret = 0;

Unnecessary assignment.

> +
> +	ret = i2c_check_functionality(client->adapter,
> +				      I2C_FUNC_SMBUS_READ_BYTE_DATA |
> +				      I2C_FUNC_SMBUS_READ_BLOCK_DATA);
> +
Unnecessary empty line. Also, assigning the return value to a variable
isn't really necessary.

	if (!i2c_check_functionality(...)) {
		...


> +	if (!ret) 
> +		ret = i2c_check_functionality(client->adapter,
> +					      I2C_FUNC_SMBUS_READ_BYTE_DATA |
> +					      I2C_FUNC_SMBUS_I2C_BLOCK);
> +		if (!ret)
> +			return -ENODEV;

		if (!i2c_check_functionality(...))
			return -ENODEV;
> +
> +		i2c_block_data_ok = true;
> +	}
> +
> +	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->rail2 = i2c_new_dummy_device(client->adapter, client->addr + 1);
> +	if (IS_ERR(data->rail2)) {
> +		dev_err(dev, "Failed to register rail2 client\n");
> +		return PTR_ERR(data->rail2);
> +	}
> +	ret = devm_add_action_or_reset(dev, max20754_remove, data);
> +	if (ret)
> +		return ret;
> +
> +	data->info = max20754_info;
> +	data->info.groups = max20754_groups;
> +	data->smbus_i2c_block_read = i2c_block_data_ok;
> +
> +	return pmbus_do_probe(client, &data->info);
> +}
> +
> +static const struct i2c_device_id max20754_id[] = {
> +	{"max20754", max20754},
> +	{}
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, max20754_id);
> +
> +static struct i2c_driver max20754_driver = {
> +	.driver = {
> +		   .name = "max20754",
> +		   },
> +	.probe_new = max20754_probe,
> +	.remove = pmbus_do_remove,

Please rebase to latest kernel. pmbus_do_remove() no longer exists.

> +	.id_table = max20754_id,
> +};
> +
> +module_i2c_driver(max20754_driver);
> +
> +MODULE_AUTHOR("Atif Emre Ofluoglu <atif.ofluoglu@...log.com>");
> +MODULE_DESCRIPTION("PMBus driver for Maxim MAX20754");
> +MODULE_LICENSE("GPL");
> +MODULE_IMPORT_NS(PMBUS);

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