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([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-203855816dcsm58617985ad.112.2024.08.25.17.15.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 25 Aug 2024 17:15:42 -0700 (PDT) Sender: Guenter Roeck Message-ID: <8e45875a-8af2-4409-8ea8-255281f97e68@roeck-us.net> Date: Sun, 25 Aug 2024 17:15:41 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] hwmon: (sht4x): add heater support To: Antoni Pokusinski , jdelvare@suse.com Cc: linux-kernel@vger.kernel.org, linux-hwmon@vger.kernel.org References: <20240825100930.205670-1-apokusinski01@gmail.com> Content-Language: en-US From: Guenter Roeck Autocrypt: addr=linux@roeck-us.net; keydata= xsFNBE6H1WcBEACu6jIcw5kZ5dGeJ7E7B2uweQR/4FGxH10/H1O1+ApmcQ9i87XdZQiB9cpN RYHA7RCEK2dh6dDccykQk3bC90xXMPg+O3R+C/SkwcnUak1UZaeK/SwQbq/t0tkMzYDRxfJ7 nyFiKxUehbNF3r9qlJgPqONwX5vJy4/GvDHdddSCxV41P/ejsZ8PykxyJs98UWhF54tGRWFl 7i1xvaDB9lN5WTLRKSO7wICuLiSz5WZHXMkyF4d+/O5ll7yz/o/JxK5vO/sduYDIlFTvBZDh gzaEtNf5tQjsjG4io8E0Yq0ViobLkS2RTNZT8ICq/Jmvl0SpbHRvYwa2DhNsK0YjHFQBB0FX IdhdUEzNefcNcYvqigJpdICoP2e4yJSyflHFO4dr0OrdnGLe1Zi/8Xo/2+M1dSSEt196rXaC kwu2KgIgmkRBb3cp2vIBBIIowU8W3qC1+w+RdMUrZxKGWJ3juwcgveJlzMpMZNyM1jobSXZ0 VHGMNJ3MwXlrEFPXaYJgibcg6brM6wGfX/LBvc/haWw4yO24lT5eitm4UBdIy9pKkKmHHh7s jfZJkB5fWKVdoCv/omy6UyH6ykLOPFugl+hVL2Prf8xrXuZe1CMS7ID9Lc8FaL1ROIN/W8Vk BIsJMaWOhks//7d92Uf3EArDlDShwR2+D+AMon8NULuLBHiEUQARAQABzTJHdWVudGVyIFJv ZWNrIChMaW51eCBhY2NvdW50KSA8bGludXhAcm9lY2stdXMubmV0PsLBgQQTAQIAKwIbAwYL CQgHAwIGFQgCCQoLBBYCAwECHgECF4ACGQEFAlVcphcFCRmg06EACgkQyx8mb86fmYFg0RAA nzXJzuPkLJaOmSIzPAqqnutACchT/meCOgMEpS5oLf6xn5ySZkl23OxuhpMZTVX+49c9pvBx hpvl5bCWFu5qC1jC2eWRYU+aZZE4sxMaAGeWenQJsiG9lP8wkfCJP3ockNu0ZXXAXwIbY1O1 c+l11zQkZw89zNgWgKobKzrDMBFOYtAh0pAInZ9TSn7oA4Ctejouo5wUugmk8MrDtUVXmEA9 7f9fgKYSwl/H7dfKKsS1bDOpyJlqhEAH94BHJdK/b1tzwJCFAXFhMlmlbYEk8kWjcxQgDWMu GAthQzSuAyhqyZwFcOlMCNbAcTSQawSo3B9yM9mHJne5RrAbVz4TWLnEaX8gA5xK3uCNCeyI sqYuzA4OzcMwnnTASvzsGZoYHTFP3DQwf2nzxD6yBGCfwNGIYfS0i8YN8XcBgEcDFMWpOQhT Pu3HeztMnF3HXrc0t7e5rDW9zCh3k2PA6D2NV4fews9KDFhLlTfCVzf0PS1dRVVWM+4jVl6l HRIAgWp+2/f8dx5vPc4Ycp4IsZN0l1h9uT7qm1KTwz+sSl1zOqKD/BpfGNZfLRRxrXthvvY8 BltcuZ4+PGFTcRkMytUbMDFMF9Cjd2W9dXD35PEtvj8wnEyzIos8bbgtLrGTv/SYhmPpahJA l8hPhYvmAvpOmusUUyB30StsHIU2LLccUPPOwU0ETofVZwEQALlLbQeBDTDbwQYrj0gbx3bq 7kpKABxN2MqeuqGr02DpS9883d/t7ontxasXoEz2GTioevvRmllJlPQERVxM8gQoNg22twF7 pB/zsrIjxkE9heE4wYfN1AyzT+AxgYN6f8hVQ7Nrc9XgZZe+8IkuW/Nf64KzNJXnSH4u6nJM J2+Dt274YoFcXR1nG76Q259mKwzbCukKbd6piL+VsT/qBrLhZe9Ivbjq5WMdkQKnP7gYKCAi pNVJC4enWfivZsYupMd9qn7Uv/oCZDYoBTdMSBUblaLMwlcjnPpOYK5rfHvC4opxl+P/Vzyz 6WC2TLkPtKvYvXmdsI6rnEI4Uucg0Au/Ulg7aqqKhzGPIbVaL+U0Wk82nz6hz+WP2ggTrY1w ZlPlRt8WM9w6WfLf2j+PuGklj37m+KvaOEfLsF1v464dSpy1tQVHhhp8LFTxh/6RWkRIR2uF I4v3Xu/k5D0LhaZHpQ4C+xKsQxpTGuYh2tnRaRL14YMW1dlI3HfeB2gj7Yc8XdHh9vkpPyuT nY/ZsFbnvBtiw7GchKKri2gDhRb2QNNDyBnQn5mRFw7CyuFclAksOdV/sdpQnYlYcRQWOUGY HhQ5eqTRZjm9z+qQe/T0HQpmiPTqQcIaG/edgKVTUjITfA7AJMKLQHgp04Vylb+G6jocnQQX JqvvP09whbqrABEBAAHCwWUEGAECAA8CGwwFAlVcpi8FCRmg08MACgkQyx8mb86fmYHNRQ/+ J0OZsBYP4leJvQF8lx9zif+v4ZY/6C9tTcUv/KNAE5leyrD4IKbnV4PnbrVhjq861it/zRQW cFpWQszZyWRwNPWUUz7ejmm9lAwPbr8xWT4qMSA43VKQ7ZCeTQJ4TC8kjqtcbw41SjkjrcTG wF52zFO4bOWyovVAPncvV9eGA/vtnd3xEZXQiSt91kBSqK28yjxAqK/c3G6i7IX2rg6pzgqh hiH3/1qM2M/LSuqAv0Rwrt/k+pZXE+B4Ud42hwmMr0TfhNxG+X7YKvjKC+SjPjqp0CaztQ0H nsDLSLElVROxCd9m8CAUuHplgmR3seYCOrT4jriMFBtKNPtj2EE4DNV4s7k0Zy+6iRQ8G8ng QjsSqYJx8iAR8JRB7Gm2rQOMv8lSRdjva++GT0VLXtHULdlzg8VjDnFZ3lfz5PWEOeIMk7Rj trjv82EZtrhLuLjHRCaG50OOm0hwPSk1J64R8O3HjSLdertmw7eyAYOo4RuWJguYMg5DRnBk WkRwrSuCn7UG+qVWZeKEsFKFOkynOs3pVbcbq1pxbhk3TRWCGRU5JolI4ohy/7JV1TVbjiDI HP/aVnm6NC8of26P40Pg8EdAhajZnHHjA7FrJXsy3cyIGqvg9os4rNkUWmrCfLLsZDHD8FnU mDW4+i+XlNFUPUYMrIKi9joBhu18ssf5i5Q= In-Reply-To: <20240825100930.205670-1-apokusinski01@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/25/24 03:09, Antoni Pokusinski wrote: > Add support for manipulating the internal heater of sht4x devices. > The heater may be used to remove condensed water on the sensor surface > which disturbs the relative humidity measurements. > Where is this seen in practice ? "may be" does not mean that the problem is actively seen. > The heater can operate at three heating levels (20, 110 or 200 > milliwatts). Also, two heating durations may be selected (0.1 or 1s). > Once the heating time elapses the heater is automatically switched off. > > Signed-off-by: Antoni Pokusinski > --- > Changes since v1: > * explain the use case of the new attributes set > * heater_enable attr: make it write-only > * heater_enable_store: define cmd as u8 instead of u8* > * heater_enable_store: remove unreachable data path > * heater_enable_store: remove unnecessary lock > * heater_enable_store: call i2c_master_send only if status==true > * define attributes as DEVICE_ATTR_* instead of SENSOR_DEVICE_ATTR_* > --- > Documentation/hwmon/sht4x.rst | 11 +++ > drivers/hwmon/sht4x.c | 126 +++++++++++++++++++++++++++++++++- > 2 files changed, 136 insertions(+), 1 deletion(-) > > diff --git a/Documentation/hwmon/sht4x.rst b/Documentation/hwmon/sht4x.rst > index daf21e763425..3ff6c08d8267 100644 > --- a/Documentation/hwmon/sht4x.rst > +++ b/Documentation/hwmon/sht4x.rst > @@ -42,4 +42,15 @@ humidity1_input Measured humidity in %H > update_interval The minimum interval for polling the sensor, > in milliseconds. Writable. Must be at least > 2000. > +heater_power The requested heater power, in milliwatts. > + Available values: 20, 110, 200 (default: 200). > +heater_time The requested operating time of the heater, > + in milliseconds. > + Available values: 100, 1000 (default 1000). > +heater_enable Enable the heater with the selected power > + and for the selected time in order to remove > + condensed water from the sensor surface. Write-only. > + > + - 0: turn off Not really. As implemented, this does not turn off the heater, it does nothing. If that is what you want' you'd have to send a command "turn off heater immediately" if such a command exists. > + - 1: turn on > =============== ============================================ > diff --git a/drivers/hwmon/sht4x.c b/drivers/hwmon/sht4x.c > index b8916d2735b5..75e092f9b80e 100644 > --- a/drivers/hwmon/sht4x.c > +++ b/drivers/hwmon/sht4x.c > @@ -11,6 +11,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -31,6 +32,12 @@ > */ > #define SHT4X_CMD_MEASURE_HPM 0b11111101 > #define SHT4X_CMD_RESET 0b10010100 > +#define SHT4X_CMD_HEATER_20_1 0b00011110 > +#define SHT4X_CMD_HEATER_20_01 0b00010101 > +#define SHT4X_CMD_HEATER_110_1 0b00101111 > +#define SHT4X_CMD_HEATER_110_01 0b00100100 > +#define SHT4X_CMD_HEATER_200_1 0b00111001 > +#define SHT4X_CMD_HEATER_200_01 0b00110010 > > #define SHT4X_CMD_LEN 1 > #define SHT4X_CRC8_LEN 1 > @@ -54,6 +61,8 @@ DECLARE_CRC8_TABLE(sht4x_crc8_table); > * @last_updated: the previous time that the SHT4X was polled > * @temperature: the latest temperature value received from the SHT4X > * @humidity: the latest humidity value received from the SHT4X > + * @heater_power: the power at which the heater will be started > + * @heater_time: the time for which the heater will remain turned on > */ > struct sht4x_data { > struct i2c_client *client; > @@ -63,6 +72,8 @@ struct sht4x_data { > long last_updated; /* in jiffies */ > s32 temperature; > s32 humidity; > + u32 heater_power; /* in milli-watts */ > + u32 heater_time; /* in milli-seconds */ > }; > > /** > @@ -215,6 +226,117 @@ static int sht4x_hwmon_write(struct device *dev, enum hwmon_sensor_types type, > } > } > > +static ssize_t heater_enable_store(struct device *dev, > + struct device_attribute *attr, > + const char *buf, > + size_t count) > +{ > + struct sht4x_data *data = dev_get_drvdata(dev); > + bool status; > + ssize_t ret; > + u8 cmd; > + > + ret = kstrtobool(buf, &status); > + if (ret) > + return ret; > + > + if (status) { > + if (data->heater_power == 20) { > + if (data->heater_time == 100) > + cmd = SHT4X_CMD_HEATER_20_01; > + else /* data->heater_time == 1000 */ > + cmd = SHT4X_CMD_HEATER_20_1; > + } else if (data->heater_power == 110) { > + if (data->heater_time == 100) > + cmd = SHT4X_CMD_HEATER_110_01; > + else /* data->heater_time == 1000 */ > + cmd = SHT4X_CMD_HEATER_110_1; > + } else if (data->heater_power == 200) { Unnecessary "if". Due to the limitations of static checkers, those may wrongly conclude that "cmd" is not initialized when passed to i2c_master_send(). > + if (data->heater_time == 100) > + cmd = SHT4X_CMD_HEATER_200_01; > + else /* data->heater_time == 1000 */ > + cmd = SHT4X_CMD_HEATER_200_1; > + } > + > + ret = i2c_master_send(data->client, &cmd, SHT4X_CMD_LEN); > + } > + > + return ret; > +} > + > +static ssize_t heater_power_show(struct device *dev, > + struct device_attribute *attr, > + char *buf) > +{ > + struct sht4x_data *data = dev_get_drvdata(dev); > + > + return sysfs_emit(buf, "%u\n", data->heater_power); > +} > + > +static ssize_t heater_power_store(struct device *dev, > + struct device_attribute *attr, > + const char *buf, > + size_t count) > +{ > + struct sht4x_data *data = dev_get_drvdata(dev); > + u32 power; > + ssize_t ret; > + > + ret = kstrtou32(buf, 10, &power); > + if (ret) > + return ret; > + > + if (power != 20 && power != 110 && power != 200) > + return -EINVAL; > + > + data->heater_power = power; > + > + return count; > +} > + > +static ssize_t heater_time_show(struct device *dev, > + struct device_attribute *attr, > + char *buf) > +{ > + struct sht4x_data *data = dev_get_drvdata(dev); > + > + return sysfs_emit(buf, "%u\n", data->heater_time); > +} > + > +static ssize_t heater_time_store(struct device *dev, > + struct device_attribute *attr, > + const char *buf, > + size_t count) > +{ > + struct sht4x_data *data = dev_get_drvdata(dev); > + u32 time; > + ssize_t ret; > + > + ret = kstrtou32(buf, 10, &time); > + if (ret) > + return ret; > + > + if (time != 100 && time != 1000) > + return -EINVAL; > + > + data->heater_time = time; > + > + return count; > +} > + > +static DEVICE_ATTR_WO(heater_enable); > +static DEVICE_ATTR_RW(heater_power); > +static DEVICE_ATTR_RW(heater_time); > + > +static struct attribute *sht4x_attrs[] = { > + &dev_attr_heater_enable.attr, > + &dev_attr_heater_power.attr, > + &dev_attr_heater_time.attr, > + NULL > +}; > + > +ATTRIBUTE_GROUPS(sht4x); > + > static const struct hwmon_channel_info * const sht4x_info[] = { > HWMON_CHANNEL_INFO(chip, HWMON_C_UPDATE_INTERVAL), > HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT), > @@ -255,6 +377,8 @@ static int sht4x_probe(struct i2c_client *client) > > data->update_interval = SHT4X_MIN_POLL_INTERVAL; > data->client = client; > + data->heater_power = 200; > + data->heater_time = 1000; > > mutex_init(&data->lock); > > @@ -270,7 +394,7 @@ static int sht4x_probe(struct i2c_client *client) > client->name, > data, > &sht4x_chip_info, > - NULL); > + sht4x_groups); > > return PTR_ERR_OR_ZERO(hwmon_dev); > }