Message-ID: <2747fc2e-0120-cc14-991e-3f5baa4a0780@roeck-us.net>
Date:   Fri, 10 Nov 2017 06:49:23 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Lei YU <mine260309@...il.com>, Mark Rutland <mark.rutland@....com>,
        Jean Delvare <jdelvare@...e.com>,
        Jonathan Corbet <corbet@....net>,
        Jiri Kosina <trivial@...nel.org>
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hwmon@...r.kernel.org, Joel Stanley <joel@....id.au>,
        Andrew Jeffery <andrew@...id.au>
Subject: Re: [PATCH v3 2/3] drivers: hwmon: Add W83773G driver

On 11/08/2017 11:09 PM, Lei YU wrote:
> Nuvoton W83773G is a hardware monitor IC providing one local
> temperature and two remote temperature sensors.
> 
> Signed-off-by: Lei YU <mine260309@...il.com>

Nicely done. Couple of nitpicks left.

Thanks!
Guenter

> ---
> v2:
>   - Rewrite the driver using regmap
>   - Add offset and update_interval
> v3:
>   - Use devm_hwmon_device_register_with_info() with is_visible/read/write
>     functions.
> ---
>   drivers/hwmon/Kconfig   |  10 ++
>   drivers/hwmon/Makefile  |   1 +
>   drivers/hwmon/w83773g.c | 348 ++++++++++++++++++++++++++++++++++++++++++++++++
>   3 files changed, 359 insertions(+)
>   create mode 100644 drivers/hwmon/w83773g.c
> 
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index d654314..11c6248 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -1710,6 +1710,16 @@ config SENSORS_VT8231
>   	  This driver can also be built as a module.  If so, the module
>   	  will be called vt8231.
>   
> +config SENSORS_W83773G
> +	tristate "Nuvoton W83773G"
> +	depends on I2C
> +	help
> +	  If you say yes here you get support for the Nuvoton W83773G hardware
> +	  monitoring chip.
> +
> +	  This driver can also be built as a module.  If so, the module
> +	  will be called w83773g.
> +
>   config SENSORS_W83781D
>   	tristate "Winbond W83781D, W83782D, W83783S, Asus AS99127F"
>   	depends on I2C
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index c84d978..0649ad8 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -13,6 +13,7 @@ obj-$(CONFIG_SENSORS_ATK0110)	+= asus_atk0110.o
>   # asb100, then w83781d go first, as they can override other drivers' addresses.
>   obj-$(CONFIG_SENSORS_ASB100)	+= asb100.o
>   obj-$(CONFIG_SENSORS_W83627HF)	+= w83627hf.o
> +obj-$(CONFIG_SENSORS_W83773G)	+= w83773g.o
>   obj-$(CONFIG_SENSORS_W83792D)	+= w83792d.o
>   obj-$(CONFIG_SENSORS_W83793)	+= w83793.o
>   obj-$(CONFIG_SENSORS_W83795)	+= w83795.o
> diff --git a/drivers/hwmon/w83773g.c b/drivers/hwmon/w83773g.c
> new file mode 100644
> index 0000000..58ac45b
> --- /dev/null
> +++ b/drivers/hwmon/w83773g.c
> @@ -0,0 +1,348 @@
> +/*
> + * Copyright (C) 2017 IBM Corp.
> + *
> + * 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.
> + *
> + * Driver for the Nuvoton W83773G SMBus temperature sensor IC.
> + * Supported models: W83773G
> + */
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/i2c.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/err.h>
> +#include <linux/of_device.h>
> +#include <linux/regmap.h>
> +
> +/* Addresses to scan */
> +static const unsigned short normal_i2c[] = { 0x4c, 0x4d, I2C_CLIENT_END };
> +
> +/* W83773 has 3 channels */
> +#define W83773_CHANNELS				3
> +
> +/* The W83773 registers */
> +#define W83773_CONVERSION_RATE_REG_READ		0x04
> +#define W83773_CONVERSION_RATE_REG_WRITE	0x0A
> +#define W83773_MANUFACTURER_ID_REG		0xFE
> +#define W83773_LOCAL_TEMP			0x00
> +
> +static const u8 W83773_STATUS[2] = { 0x02, 0x17 };
> +
> +static const u8 W83773_TEMP_LSB[2] = { 0x10, 0x25 };
> +static const u8 W83773_TEMP_MSB[2] = { 0x01, 0x24 };
> +
> +static const u8 W83773_OFFSET_LSB[2] = { 0x12, 0x16 };
> +static const u8 W83773_OFFSET_MSB[2] = { 0x11, 0x15 };
> +
> +/* this is the number of sensors in the device */
> +static const struct i2c_device_id w83773_id[] = {
> +	{ "w83773g" },
> +	{ }
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, w83773_id);
> +
> +static const struct of_device_id w83773_of_match[] = {
> +	{
> +		.compatible = "nuvoton,w83773g"
> +	},
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, w83773_of_match);
> +
> +static inline long temp_of_local(s8 reg)
> +{
> +	return reg * 1000;
> +}
> +
> +static inline long temp_of_remote(s8 hb, u8 lb)
> +{
> +	return (hb << 3 | lb >> 5) * 125;
> +}
> +
> +static int get_local_temp(struct regmap *regmap, long *val)
> +{
> +	unsigned int regval;
> +	int ret;
> +
> +	ret = regmap_read(regmap, W83773_LOCAL_TEMP, &regval);
> +	if (ret < 0)
> +		return ret;
> +
> +	*val = temp_of_local(regval);
> +	return 0;
> +}
> +
> +static int get_remote_temp(struct regmap *regmap, int index, long *val)
> +{
> +	unsigned int regval_high;
> +	unsigned int regval_low;
> +	int ret;
> +
> +	ret = regmap_read(regmap, W83773_TEMP_MSB[index], &regval_high);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_read(regmap, W83773_TEMP_LSB[index], &regval_low);
> +	if (ret < 0)
> +		return ret;
> +
> +	*val = temp_of_remote(regval_high, regval_low);
> +	return 0;
> +}
> +
> +static int get_fault(struct regmap *regmap, int index, long *val)
> +{
> +	unsigned int regval;
> +	int ret;
> +
> +	ret = regmap_read(regmap, W83773_STATUS[index], &regval);
> +
Drop the empty line please.

> +	if (ret < 0)
> +		return ret;
> +
> +	*val = (u8)regval & 0x04 >> 2;
> +	return 0;
> +}
> +
> +static int get_offset(struct regmap *regmap, int index, long *val)
> +{
> +	unsigned int regval_high;
> +	unsigned int regval_low;
> +	int ret;
> +
> +	ret = regmap_read(regmap, W83773_OFFSET_MSB[index], &regval_high);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_read(regmap, W83773_OFFSET_LSB[index], &regval_low);
> +	if (ret < 0)
> +		return ret;
> +
> +	*val = temp_of_remote(regval_high, regval_low);
> +	return 0;
> +}
> +
> +static int set_offset(struct regmap *regmap, int index, long val)
> +{
> +	int ret;
> +	u8 high_byte;
> +	u8 low_byte;
> +
> +	val = clamp_val(val, -127825, 127825);
> +	/* offset value equals to (high_byte << 3 | low_byte >> 5) * 125 */
> +	val /= 125;
> +	high_byte = val >> 3;
> +	low_byte = (val & 0x07) << 5;
> +
> +	ret = regmap_write(regmap, W83773_OFFSET_MSB[index], high_byte);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = regmap_write(regmap, W83773_OFFSET_LSB[index], low_byte);
> +	if (ret < 0)
> +		return ret;
> +
> +	return 0;

For the second call,

	return regmap_write(regmap, W83773_OFFSET_LSB[index], low_byte);

> +}
> +
> +static int get_update_interval(struct regmap *regmap, long *val)
> +{
> +	unsigned int regval;
> +	int ret;
> +
> +	ret = regmap_read(regmap, W83773_CONVERSION_RATE_REG_READ, &regval);
> +	if (ret < 0)
> +		return ret;
> +
> +	*val = 16000 >> regval;
> +	return 0;
> +}
> +
> +static int set_update_interval(struct regmap *regmap, long val)
> +{
> +	int ret;
> +	int rate;
> +
> +	if (val <= 0)
> +		return -EINVAL;
> +
Not really needed since you are clamping below. For consistency I would suggest
to drop it (otherwise 0 returns -EINVAL, 1 translates to 62).

> +	/*
> +	 * For valid rates, interval can be calculated as
> +	 *	interval = (1 << (8 - rate)) * 62.5;
> +	 * Rounded rate is therefore
> +	 *	rate = 8 - __fls(interval * 8 / (62.5 * 7));
> +	 * Use clamp_val() to avoid overflows, and to ensure valid input
> +	 * for __fls.
> +	 */
> +	val = clamp_val(val, 62, 16000) * 10;
> +	rate = 8 - __fls((val * 8 / (625 * 7)));
> +	ret = regmap_write(regmap, W83773_CONVERSION_RATE_REG_WRITE, rate);
> +	if (ret < 0)
> +		return ret;
> +	return 0;

just
	return regmap_write(regmap, W83773_CONVERSION_RATE_REG_WRITE, rate);

> +}
> +
> +static int w83773_read(struct device *dev, enum hwmon_sensor_types type,
> +		       u32 attr, int channel, long *val)
> +{
> +	struct regmap *regmap = dev_get_drvdata(dev);
> +
> +	if (type == hwmon_chip) {
> +		if (attr == hwmon_chip_update_interval)
> +			return get_update_interval(regmap, val);
> +		else

else not needed after return

> +			return -EOPNOTSUPP;
> +	}
> +
> +	switch (attr) {
> +	case hwmon_temp_input:
> +		if (channel == 0)
> +			return get_local_temp(regmap, val);
> +		else

else not needed after return

> +			return get_remote_temp(regmap, channel - 1, val);
> +	case hwmon_temp_fault:
> +		return get_fault(regmap, channel - 1, val);
> +	case hwmon_temp_offset:
> +		return get_offset(regmap, channel - 1, val);
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int w83773_write(struct device *dev, enum hwmon_sensor_types type,
> +			u32 attr, int channel, long val)
> +{
> +	struct regmap *regmap = dev_get_drvdata(dev);
> +
> +	if (type == hwmon_chip && attr == hwmon_chip_update_interval)
> +		return set_update_interval(regmap, val);
> +
> +	if (type == hwmon_temp && attr == hwmon_temp_offset)
> +		return set_offset(regmap, channel - 1, val);
> +
> +	return -EOPNOTSUPP;
> +}
> +
> +static umode_t w83773_is_visible(const void *data, enum hwmon_sensor_types type,
> +				 u32 attr, int channel)
> +{
> +	switch (type) {
> +	case hwmon_chip:
> +		switch (attr) {
> +		case hwmon_chip_update_interval:
> +			return 0644;
> +		}
> +		break;
> +	case hwmon_temp:
> +		switch (attr) {
> +		case hwmon_temp_input:
> +			return 0444;
> +		case hwmon_temp_fault:

The above case statements can be combined.

> +			return 0444;
> +		case hwmon_temp_offset:
> +			return 0644;

Wonder if static analyzers complain here and above because
of the missing default: case. Any idea ?

> +		}
> +		break;
> +	default:
> +		break;
> +	}
> +	return 0;
> +}
> +
> +static const u32 w83773_chip_config[] = {
> +	HWMON_C_REGISTER_TZ | HWMON_C_UPDATE_INTERVAL,
> +	0
> +};
> +
> +static const struct hwmon_channel_info w83773_chip = {
> +	.type = hwmon_chip,
> +	.config = w83773_chip_config,
> +};
> +
> +static const u32 w83773_temp_config[] = {
> +	HWMON_T_INPUT,
> +	HWMON_T_INPUT | HWMON_T_FAULT | HWMON_T_OFFSET,
> +	HWMON_T_INPUT | HWMON_T_FAULT | HWMON_T_OFFSET,
> +	0
> +};
> +
> +static const struct hwmon_channel_info w83773_temp = {
> +	.type = hwmon_temp,
> +	.config = w83773_temp_config,
> +};
> +
> +static const struct hwmon_channel_info *w83773_info[] = {
> +	&w83773_chip,
> +	&w83773_temp,
> +	NULL
> +};
> +
> +static const struct hwmon_ops w83773_ops = {
> +	.is_visible = w83773_is_visible,
> +	.read = w83773_read,
> +	.write = w83773_write,
> +};
> +
> +static const struct hwmon_chip_info w83773_chip_info = {
> +	.ops = &w83773_ops,
> +	.info = w83773_info,
> +};
> +
> +static const struct regmap_config w83773_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +};
> +
> +static int w83773_probe(struct i2c_client *client,
> +			const struct i2c_device_id *id)
> +{
> +	struct device *dev = &client->dev;
> +	struct device *hwmon_dev;
> +	struct regmap *regmap;
> +	int ret;
> +
> +	regmap = devm_regmap_init_i2c(client, &w83773_regmap_config);
> +	if (IS_ERR(regmap)) {
> +		dev_err(dev, "failed to allocate register map\n");
> +		return PTR_ERR(regmap);
> +	}
> +
> +	/* Set the conversion rate to 2 Hz */
> +	ret = regmap_write(regmap, W83773_CONVERSION_RATE_REG_WRITE, 0x05);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "error writing config rate register\n");
> +		return ret;
> +	}
> +
> +	i2c_set_clientdata(client, regmap);
> +
> +	hwmon_dev = devm_hwmon_device_register_with_info(dev,
> +							 client->name,
> +							 regmap,
> +							 &w83773_chip_info,
> +							 NULL);
> +	return PTR_ERR_OR_ZERO(hwmon_dev);
> +}
> +
> +static struct i2c_driver w83773_driver = {
> +	.class = I2C_CLASS_HWMON,
> +	.driver = {
> +		.name	= "w83773g",
> +		.of_match_table = of_match_ptr(w83773_of_match),
> +	},
> +	.probe = w83773_probe,
> +	.id_table = w83773_id,
> +	.address_list = normal_i2c,

address_list is only used if there is a detect function, so you can drop it.

> +};
> +
> +module_i2c_driver(w83773_driver);
> +
> +MODULE_AUTHOR("Lei YU <mine260309@...il.com>");
> +MODULE_DESCRIPTION("W83773G temperature sensor driver");
> +MODULE_LICENSE("GPL");
> 

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