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290 lines
7.7 KiB
290 lines
7.7 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* Sensirion SHTC1 humidity and temperature sensor driver |
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* |
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* Copyright (C) 2014 Sensirion AG, Switzerland |
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* Author: Johannes Winkelmann <[email protected]> |
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*/ |
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#include <linux/module.h> |
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#include <linux/init.h> |
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#include <linux/slab.h> |
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#include <linux/i2c.h> |
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#include <linux/hwmon.h> |
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#include <linux/hwmon-sysfs.h> |
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#include <linux/err.h> |
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#include <linux/delay.h> |
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#include <linux/platform_data/shtc1.h> |
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#include <linux/of.h> |
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/* commands (high precision mode) */ |
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static const unsigned char shtc1_cmd_measure_blocking_hpm[] = { 0x7C, 0xA2 }; |
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static const unsigned char shtc1_cmd_measure_nonblocking_hpm[] = { 0x78, 0x66 }; |
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/* commands (low precision mode) */ |
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static const unsigned char shtc1_cmd_measure_blocking_lpm[] = { 0x64, 0x58 }; |
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static const unsigned char shtc1_cmd_measure_nonblocking_lpm[] = { 0x60, 0x9c }; |
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/* command for reading the ID register */ |
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static const unsigned char shtc1_cmd_read_id_reg[] = { 0xef, 0xc8 }; |
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/* |
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* constants for reading the ID register |
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* SHTC1: 0x0007 with mask 0x003f |
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* SHTW1: 0x0007 with mask 0x003f |
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* SHTC3: 0x0807 with mask 0x083f |
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*/ |
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#define SHTC3_ID 0x0807 |
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#define SHTC3_ID_MASK 0x083f |
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#define SHTC1_ID 0x0007 |
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#define SHTC1_ID_MASK 0x003f |
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/* delays for non-blocking i2c commands, both in us */ |
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#define SHTC1_NONBLOCKING_WAIT_TIME_HPM 14400 |
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#define SHTC1_NONBLOCKING_WAIT_TIME_LPM 1000 |
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#define SHTC3_NONBLOCKING_WAIT_TIME_HPM 12100 |
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#define SHTC3_NONBLOCKING_WAIT_TIME_LPM 800 |
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#define SHTC1_CMD_LENGTH 2 |
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#define SHTC1_RESPONSE_LENGTH 6 |
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enum shtcx_chips { |
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shtc1, |
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shtc3, |
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}; |
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struct shtc1_data { |
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struct i2c_client *client; |
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struct mutex update_lock; |
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bool valid; |
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unsigned long last_updated; /* in jiffies */ |
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const unsigned char *command; |
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unsigned int nonblocking_wait_time; /* in us */ |
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struct shtc1_platform_data setup; |
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enum shtcx_chips chip; |
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int temperature; /* 1000 * temperature in dgr C */ |
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int humidity; /* 1000 * relative humidity in %RH */ |
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}; |
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static int shtc1_update_values(struct i2c_client *client, |
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struct shtc1_data *data, |
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char *buf, int bufsize) |
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{ |
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int ret = i2c_master_send(client, data->command, SHTC1_CMD_LENGTH); |
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if (ret != SHTC1_CMD_LENGTH) { |
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dev_err(&client->dev, "failed to send command: %d\n", ret); |
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return ret < 0 ? ret : -EIO; |
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} |
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/* |
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* In blocking mode (clock stretching mode) the I2C bus |
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* is blocked for other traffic, thus the call to i2c_master_recv() |
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* will wait until the data is ready. For non blocking mode, we |
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* have to wait ourselves. |
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*/ |
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if (!data->setup.blocking_io) |
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usleep_range(data->nonblocking_wait_time, |
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data->nonblocking_wait_time + 1000); |
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ret = i2c_master_recv(client, buf, bufsize); |
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if (ret != bufsize) { |
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dev_err(&client->dev, "failed to read values: %d\n", ret); |
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return ret < 0 ? ret : -EIO; |
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} |
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return 0; |
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} |
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/* sysfs attributes */ |
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static struct shtc1_data *shtc1_update_client(struct device *dev) |
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{ |
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struct shtc1_data *data = dev_get_drvdata(dev); |
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struct i2c_client *client = data->client; |
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unsigned char buf[SHTC1_RESPONSE_LENGTH]; |
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int val; |
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int ret = 0; |
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mutex_lock(&data->update_lock); |
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if (time_after(jiffies, data->last_updated + HZ / 10) || !data->valid) { |
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ret = shtc1_update_values(client, data, buf, sizeof(buf)); |
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if (ret) |
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goto out; |
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/* |
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* From datasheet: |
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* T = -45 + 175 * ST / 2^16 |
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* RH = 100 * SRH / 2^16 |
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* |
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* Adapted for integer fixed point (3 digit) arithmetic. |
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*/ |
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val = be16_to_cpup((__be16 *)buf); |
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data->temperature = ((21875 * val) >> 13) - 45000; |
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val = be16_to_cpup((__be16 *)(buf + 3)); |
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data->humidity = ((12500 * val) >> 13); |
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data->last_updated = jiffies; |
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data->valid = true; |
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} |
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out: |
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mutex_unlock(&data->update_lock); |
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return ret == 0 ? data : ERR_PTR(ret); |
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} |
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static ssize_t temp1_input_show(struct device *dev, |
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struct device_attribute *attr, |
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char *buf) |
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{ |
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struct shtc1_data *data = shtc1_update_client(dev); |
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if (IS_ERR(data)) |
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return PTR_ERR(data); |
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return sprintf(buf, "%d\n", data->temperature); |
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} |
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static ssize_t humidity1_input_show(struct device *dev, |
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struct device_attribute *attr, char *buf) |
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{ |
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struct shtc1_data *data = shtc1_update_client(dev); |
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if (IS_ERR(data)) |
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return PTR_ERR(data); |
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return sprintf(buf, "%d\n", data->humidity); |
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} |
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static DEVICE_ATTR_RO(temp1_input); |
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static DEVICE_ATTR_RO(humidity1_input); |
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static struct attribute *shtc1_attrs[] = { |
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&dev_attr_temp1_input.attr, |
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&dev_attr_humidity1_input.attr, |
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NULL |
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}; |
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ATTRIBUTE_GROUPS(shtc1); |
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static void shtc1_select_command(struct shtc1_data *data) |
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{ |
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if (data->setup.high_precision) { |
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data->command = data->setup.blocking_io ? |
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shtc1_cmd_measure_blocking_hpm : |
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shtc1_cmd_measure_nonblocking_hpm; |
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data->nonblocking_wait_time = (data->chip == shtc1) ? |
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SHTC1_NONBLOCKING_WAIT_TIME_HPM : |
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SHTC3_NONBLOCKING_WAIT_TIME_HPM; |
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} else { |
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data->command = data->setup.blocking_io ? |
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shtc1_cmd_measure_blocking_lpm : |
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shtc1_cmd_measure_nonblocking_lpm; |
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data->nonblocking_wait_time = (data->chip == shtc1) ? |
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SHTC1_NONBLOCKING_WAIT_TIME_LPM : |
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SHTC3_NONBLOCKING_WAIT_TIME_LPM; |
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} |
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} |
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static const struct i2c_device_id shtc1_id[]; |
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static int shtc1_probe(struct i2c_client *client) |
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{ |
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int ret; |
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u16 id_reg; |
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char id_reg_buf[2]; |
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struct shtc1_data *data; |
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struct device *hwmon_dev; |
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enum shtcx_chips chip = i2c_match_id(shtc1_id, client)->driver_data; |
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struct i2c_adapter *adap = client->adapter; |
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struct device *dev = &client->dev; |
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struct device_node *np = dev->of_node; |
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if (!i2c_check_functionality(adap, I2C_FUNC_I2C)) { |
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dev_err(dev, "plain i2c transactions not supported\n"); |
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return -ENODEV; |
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} |
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ret = i2c_master_send(client, shtc1_cmd_read_id_reg, SHTC1_CMD_LENGTH); |
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if (ret != SHTC1_CMD_LENGTH) { |
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dev_err(dev, "could not send read_id_reg command: %d\n", ret); |
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return ret < 0 ? ret : -ENODEV; |
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} |
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ret = i2c_master_recv(client, id_reg_buf, sizeof(id_reg_buf)); |
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if (ret != sizeof(id_reg_buf)) { |
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dev_err(dev, "could not read ID register: %d\n", ret); |
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return -ENODEV; |
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} |
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id_reg = be16_to_cpup((__be16 *)id_reg_buf); |
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if (chip == shtc3) { |
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if ((id_reg & SHTC3_ID_MASK) != SHTC3_ID) { |
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dev_err(dev, "SHTC3 ID register does not match\n"); |
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return -ENODEV; |
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} |
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} else if ((id_reg & SHTC1_ID_MASK) != SHTC1_ID) { |
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dev_err(dev, "SHTC1 ID register does not match\n"); |
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return -ENODEV; |
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} |
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data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); |
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if (!data) |
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return -ENOMEM; |
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data->setup.blocking_io = false; |
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data->setup.high_precision = true; |
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data->client = client; |
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data->chip = chip; |
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if (np) { |
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data->setup.blocking_io = of_property_read_bool(np, "sensirion,blocking-io"); |
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data->setup.high_precision = !of_property_read_bool(np, "sensicon,low-precision"); |
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} else { |
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if (client->dev.platform_data) |
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data->setup = *(struct shtc1_platform_data *)dev->platform_data; |
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} |
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shtc1_select_command(data); |
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mutex_init(&data->update_lock); |
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hwmon_dev = devm_hwmon_device_register_with_groups(dev, |
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client->name, |
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data, |
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shtc1_groups); |
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if (IS_ERR(hwmon_dev)) |
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dev_dbg(dev, "unable to register hwmon device\n"); |
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return PTR_ERR_OR_ZERO(hwmon_dev); |
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} |
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/* device ID table */ |
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static const struct i2c_device_id shtc1_id[] = { |
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{ "shtc1", shtc1 }, |
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{ "shtw1", shtc1 }, |
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{ "shtc3", shtc3 }, |
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{ } |
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}; |
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MODULE_DEVICE_TABLE(i2c, shtc1_id); |
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static const struct of_device_id shtc1_of_match[] = { |
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{ .compatible = "sensirion,shtc1" }, |
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{ .compatible = "sensirion,shtw1" }, |
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{ .compatible = "sensirion,shtc3" }, |
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{ } |
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}; |
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MODULE_DEVICE_TABLE(of, shtc1_of_match); |
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static struct i2c_driver shtc1_i2c_driver = { |
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.driver = { |
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.name = "shtc1", |
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.of_match_table = shtc1_of_match, |
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}, |
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.probe_new = shtc1_probe, |
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.id_table = shtc1_id, |
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}; |
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module_i2c_driver(shtc1_i2c_driver); |
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MODULE_AUTHOR("Johannes Winkelmann <[email protected]>"); |
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MODULE_DESCRIPTION("Sensirion SHTC1 humidity and temperature sensor driver"); |
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MODULE_LICENSE("GPL");
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