Re: [PATCH 1/2] hwmon: (pmbus/max20754) Add support for MAX20754

From: Guenter Roeck
Date: Wed Jul 13 2022 - 10:16:23 EST

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

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@xxxxxxxxxx>
> + * 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@xxxxxxxxxx>");
> +MODULE_DESCRIPTION("PMBus driver for Maxim MAX20754");
> +MODULE_LICENSE("GPL");
> +MODULE_IMPORT_NS(PMBUS);

Next message: Sudeep Holla: "Re: [PATCH -next] arch_topology: Fix cache attributes detection in the CPU hotplug path"
Previous message: Sam Protsenko: "Re: [PATCH 0/4] iommu/exynos: Add basic support for SysMMU v7"
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