Re: [PATCH v4 2/2] hwmon: (hs3001) Add driver for Renesas HS3001
From: Guenter Roeck
Date: Fri Jul 21 2023 - 10:00:20 EST
On Fri, Jul 21, 2023 at 12:05:19PM +0200, werneazc@xxxxxxxxx wrote:
> From: Andre Werner <andre.werner@xxxxxxxxxxxxxxxxxxxxx>
>
> Add base support for Renesas HS3001 temperature
> and humidity sensors and its compatibles HS3002,
> HS3003 and HS3004.
>
> The sensor has a fix I2C address 0x44. The resolution
> is fixed to 14bit (ref. Missing feature).
>
> Missing feature:
> - Accessing non-volatile memory: Custom board has no
> possibility to control voltage supply of sensor. Thus,
> we cannot send the necessary control commands within
> the first 10ms after power-on.
>
> Signed-off-by: Andre Werner <andre.werner@xxxxxxxxxxxxxxxxxxxxx>
>
> ---
> Changelog:
> v1: Initial version
> v2: Extensive refactoring following recommendations of reviewers:
> - Delete unused defines and device properties. These are added in
> the initial version because the device supports a programming mode,
> but I was not able to implement it, because the custom board was
> not able to control the power supply of the device and so I cannot
> enter the programming mode of the device.
> - Correct misunderstanding comments for defines.
> - Delete mutexes for data and I2C bus accesses.
> - Replace attributes with recommended chip-info structure. In the
> initial version I followed the sth3x.c implementation that uses
> files and attributes in sysfs. The show functions are replaced by
> is_visible and read callbacks from the HWMON ABI. I also delete pointless
> function argument checks.
> - Correct Yoda programming.
> - Refactor probe function and delete sleep and measurement of humidity
> and temperature in probe function. I kept an initial I2C
> communication to ensure that the device is accessible during probe.
> - Reduce the number of attributes to humidity and temperature input.
> v3: Delete chip data because it is unused.
> v4: Refactor driver as follows:
> - Delete further unused defines
> - Replace masks and operations with GENMASK and FIELD_GET macros
> - Add mutex to protect chip wakeup and data transfer operations on bus
> - Reformat driver as requested
> - Make hs3001_is_visible and hs3001_read function static
> ---
> Documentation/hwmon/hs3001.rst | 37 +++++
> MAINTAINERS | 6 +
> drivers/hwmon/Kconfig | 10 ++
> drivers/hwmon/Makefile | 1 +
> drivers/hwmon/hs3001.c | 250 +++++++++++++++++++++++++++++++++
> 5 files changed, 304 insertions(+)
> create mode 100644 Documentation/hwmon/hs3001.rst
> create mode 100644 drivers/hwmon/hs3001.c
>
> diff --git a/Documentation/hwmon/hs3001.rst b/Documentation/hwmon/hs3001.rst
> new file mode 100644
> index 000000000000..703fb9c45313
> --- /dev/null
> +++ b/Documentation/hwmon/hs3001.rst
> @@ -0,0 +1,37 @@
> +.. SPDX-License-Identifier: GPL-2.0-or-later
> +
> +Kernel driver HS3001
> +===================
> +
> +Supported chips:
> +
> + * Renesas HS3001, HS3002, HS3003, HS3004
> +
> + Prefix: 'hs3001'
> +
> + Addresses scanned: -
> +
> + Datasheet: https://www.renesas.com/us/en/document/dst/hs300x-datasheet?r=417401
> +
> +Author:
> +
> + - Andre Werner <andre.werner@xxxxxxxxxxxxxxxxxxxxx>
> +
> +Description
> +-----------
> +
> +This driver implements support for the Renesas HS3001 chips, a humidity
> +and temperature family. Temperature is measured in degrees celsius, relative
> +humidity is expressed as a percentage. In the sysfs interface, all values are
> +scaled by 1000, i.e. the value for 31.5 degrees celsius is 31500.
> +
> +The device communicates with the I2C protocol. Sensors have the I2C
> +address 0x44 by default.
> +
> +sysfs-Interface
> +---------------
> +
> +===============================================================================
> +temp1_input: temperature input
> +humidity1_input: humidity input
> +===============================================================================
> diff --git a/MAINTAINERS b/MAINTAINERS
> index aee340630eca..25d5282b43aa 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -9494,6 +9494,12 @@ S: Maintained
> W: http://artax.karlin.mff.cuni.cz/~mikulas/vyplody/hpfs/index-e.cgi
> F: fs/hpfs/
>
> +HS3001 Hardware Temperature and Humidity Sensor
> +M: Andre Werner <andre.werner@xxxxxxxxxxxxxxxxxxxxx>
> +L: linux-hwmon@xxxxxxxxxxxxxxx
> +S: Maintained
> +F: drivers/hwmon/hs3001.c
> +
> HSI SUBSYSTEM
> M: Sebastian Reichel <sre@xxxxxxxxxx>
> S: Maintained
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 307477b8a371..ca6be5a23271 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -734,6 +734,16 @@ config SENSORS_HIH6130
> This driver can also be built as a module. If so, the module
> will be called hih6130.
>
> +config SENSORS_HS3001
> + tristate "Renesas HS3001 humidity and temperature sensors"
> + depends on I2C
> + help
> + If you say yes here you get support for the Renesas HS3001,
> + to HS3004 humidity and temperature sensors.
> +
> + This driver can also be built as a module. If so, the module
> + will be called hs3001.
> +
> config SENSORS_IBMAEM
> tristate "IBM Active Energy Manager temperature/power sensors and control"
> select IPMI_SI
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 3f4b0fda0998..cdae4e1fc919 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -86,6 +86,7 @@ obj-$(CONFIG_SENSORS_GSC) += gsc-hwmon.o
> obj-$(CONFIG_SENSORS_GPIO_FAN) += gpio-fan.o
> obj-$(CONFIG_SENSORS_GXP_FAN_CTRL) += gxp-fan-ctrl.o
> obj-$(CONFIG_SENSORS_HIH6130) += hih6130.o
> +obj-$(CONFIG_SENSORS_HS3001) += hs3001.o
> obj-$(CONFIG_SENSORS_ULTRA45) += ultra45_env.o
> obj-$(CONFIG_SENSORS_I5500) += i5500_temp.o
> obj-$(CONFIG_SENSORS_I5K_AMB) += i5k_amb.o
> diff --git a/drivers/hwmon/hs3001.c b/drivers/hwmon/hs3001.c
> new file mode 100644
> index 000000000000..483b47c81b83
> --- /dev/null
> +++ b/drivers/hwmon/hs3001.c
> @@ -0,0 +1,250 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * This is a non-complete driver implementation for the
> + * HS3001 humidity and temperature sensor and compatibles. It does not include
> + * the configuration possibilities, where it needs to be set to 'programming mode'
> + * during power-up.
> + *
> + *
> + * Copyright (C) 2023 SYS TEC electronic AG
> + * Author: Andre Werner <andre.werner@xxxxxxxxxxxxxxxxxxxxx>
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/hwmon.h>
> +#include <linux/i2c.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +
> +/* Measurement times */
> +#define HS3001_WAKEUP_TIME 100 /* us */
> +#define HS3001_8BIT_RESOLUTION 550 /* us */
> +#define HS3001_10BIT_RESOLUTION 1310 /* us */
> +#define HS3001_12BIT_RESOLUTION 4500 /* us */
> +#define HS3001_14BIT_RESOLUTION 16900 /* us */
> +
> +#define HS3001_RESPONSE_LENGTH 4
> +
> +#define HS3001_FIXPOINT_ARITH 1000U
> +
> +#define HS3001_MASK_HUMIDITY_0X3FFF GENMASK(13, 0)
> +#define HS3001_MASK_STATUS_0XC0 GENMASK(7, 6)
> +
> +/* Definitions for Status Bits of A/D Data */
> +#define HS3001_DATA_VALID 0x00 /* Valid Data */
> +#define HS3001_DATA_STALE 0x01 /* Stale Data */
> +
> +struct hs3001_data {
> + struct i2c_client *client;
> + struct mutex i2c_lock; /* lock for sending i2c commands */
> + u32 wait_time; /* in us */
> + int temperature; /* in milli degree */
> + u32 humidity; /* in milli % */
> +};
> +
> +static int hs3001_extract_temperature(u16 raw)
> +{
> + /* fixpoint arithmetic 1 digit */
> + int temp = (raw >> 2) * HS3001_FIXPOINT_ARITH;
> +
> + temp /= (1 << 14) - 1;
> +
> + return temp * 165 - 40 * HS3001_FIXPOINT_ARITH;
This code results in unnecessary precision loss.
Code such as
unsigned int temp = (raw >> 2) * HS3001_FIXPOINT_ARITH * 165;
temp /= (1 << 14) - 1;
return (int)temp - 40 * HS3001_FIXPOINT_ARITH;
would be functionally identical and avoid the precision loss.
> +}
> +
> +static u32 hs3001_extract_humidity(u16 raw)
> +{
> + u32 hum = (raw & HS3001_MASK_HUMIDITY_0X3FFF) * HS3001_FIXPOINT_ARITH;
> +
> + hum /= (1 << 14) - 1;
> +
> + return hum * 100;
This code results in unnecessary precision loss.
Code such as
u32 hum = (raw & HS3001_MASK_HUMIDITY_0X3FFF) * HS3001_FIXPOINT_ARITH * 100;
return hum / (1 << 14) - 1;
would be functionally identical and avoid the precision loss.
If you explicitly _want_ the precision loss in those functions,
please add comments explaining the reason.
> +}
> +
> +static int hs3001_data_fetch_command(struct i2c_client *client,
> + struct hs3001_data *data)
> +{
> + int ret;
> + u8 buf[HS3001_RESPONSE_LENGTH];
> + u8 hs3001_status;
> +
> + ret = i2c_master_recv(client, buf, HS3001_RESPONSE_LENGTH);
> + if (ret != HS3001_RESPONSE_LENGTH) {
> + ret = ret < 0 ? ret : -EIO;
> + dev_dbg(&client->dev,
> + "Error in i2c communication. Error code: %d.\n", ret);
> + return ret;
> + }
> +
> + hs3001_status = FIELD_GET(HS3001_MASK_STATUS_0XC0, buf[0]);
> + if (hs3001_status == HS3001_DATA_STALE) {
> + dev_dbg(&client->dev, "Sensor busy.\n");
> + return -EBUSY;
> + }
> + if (hs3001_status != HS3001_DATA_VALID) {
> + dev_dbg(&client->dev, "Data invalid.\n");
> + return -EIO;
> + }
> +
> + data->humidity =
> + hs3001_extract_humidity(be16_to_cpup((__be16 *)&buf[0]));
> + data->temperature =
> + hs3001_extract_temperature(be16_to_cpup((__be16 *)&buf[2]));
> +
> + return 0;
> +}
> +
> +static umode_t hs3001_is_visible(const void *data, enum hwmon_sensor_types type,
> + u32 attr, int channel)
> +{
> + /* Both, humidity and temperature can only be read. */
> + return 0444;
> +}
> +
> +static int hs3001_read(struct device *dev, enum hwmon_sensor_types type,
> + u32 attr, int channel, long *val)
> +{
> + struct hs3001_data *data = dev_get_drvdata(dev);
> + struct i2c_client *client = data->client;
> + int ret;
> +
> + /* Protected section beginn */
> + mutex_lock(&data->i2c_lock);
> + ret = i2c_master_send(client, NULL, 0);
> + if (ret < 0)
> + return ret;
> +
> + /*
> + * Sensor needs some time to process measurement depending on
> + * resolution (ref. datasheet)
> + */
> + fsleep(data->wait_time);
> +
> + ret = hs3001_data_fetch_command(client, data);
> + mutex_unlock(&data->i2c_lock);
> + /* Protected section end */
> +
> + if (ret < 0)
> + return ret;
> +
> + switch (type) {
> + case hwmon_temp:
> + switch (attr) {
> + case hwmon_temp_input:
> + *val = data->temperature;
> + break;
> + default:
> + return -EINVAL;
> + }
> + break;
> + case hwmon_humidity:
> + switch (attr) {
> + case hwmon_humidity_input:
> + *val = data->humidity;
> + break;
> + default:
> + return -EINVAL;
> + }
> + break;
> + default:
> + return -EINVAL;
> + }
> +
> + return 0;
> +}
> +
> +static const struct hwmon_channel_info *hs3001_info[] = {
> + HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
> + HWMON_CHANNEL_INFO(humidity, HWMON_H_INPUT),
> + NULL
> +};
> +
> +static const struct hwmon_ops hs3001_hwmon_ops = {
> + .is_visible = hs3001_is_visible,
> + .read = hs3001_read,
> +};
> +
> +static const struct hwmon_chip_info hs3001_chip_info = {
> + .ops = &hs3001_hwmon_ops,
> + .info = hs3001_info,
> +};
> +
> +/* device ID table */
> +static const struct i2c_device_id hs3001_ids[] = {
> + { "hs3001", 0 },
> + { },
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, hs3001_ids);
> +
> +static const struct of_device_id hs3001_of_match[] = {
> + {.compatible = "renesas,hs3001"},
> + { },
> +};
> +
> +MODULE_DEVICE_TABLE(of, hs3001_of_match);
> +
> +static int hs3001_probe(struct i2c_client *client)
> +{
> + struct hs3001_data *data;
> + struct device *hwmon_dev;
> + struct device *dev = &client->dev;
> + int ret;
> +
> + if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
> + return -EOPNOTSUPP;
> +
> + data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
> + if (!data)
> + return -ENOMEM;
> +
> + data->client = client;
> +
> + /*
> + * Measurement time = wake-up time + measurement time temperature
> + * + measurment time humidity. This is currently static, because
> + * enabling programming mode is not supported, yet.
> + */
> + data->wait_time = (HS3001_WAKEUP_TIME + HS3001_14BIT_RESOLUTION +
> + HS3001_14BIT_RESOLUTION);
> +
> + mutex_init(&data->i2c_lock);
> +
> + /* Test access to device */
> + ret = i2c_master_send(client, NULL, 0);
> + if (ret)
> + return ret;
Again, this code only checks if a device is there, not that a HS300{1,2,3,4}
is there. It does not add any value, we don't do this for other chips,
and I won't accept this kind of code. Please drop.
Guenter
> +
> + hwmon_dev = devm_hwmon_device_register_with_info(dev,
> + client->name,
> + data,
> + &hs3001_chip_info,
> + NULL);
> +
> + if (IS_ERR(hwmon_dev))
> + return dev_err_probe(dev, PTR_ERR(hwmon_dev),
> + "Unable to register hwmon device.\n");
> +
> + return 0;
> +}
> +
> +static struct i2c_driver hs3001_i2c_driver = {
> + .driver = {
> + .name = "hs3001",
> + .of_match_table = hs3001_of_match,
> + },
> + .probe_new = hs3001_probe,
> + .id_table = hs3001_ids,
> +};
> +
> +module_i2c_driver(hs3001_i2c_driver);
> +
> +MODULE_AUTHOR("Andre Werner <andre.werner@xxxxxxxxxxxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("HS3001 humidity and temperature sensor base driver");
> +MODULE_LICENSE("GPL");
> --
> 2.41.0
>