diff options
Diffstat (limited to 'drivers/hwmon/max31827.c')
| -rw-r--r-- | drivers/hwmon/max31827.c | 466 |
1 files changed, 466 insertions, 0 deletions
diff --git a/drivers/hwmon/max31827.c b/drivers/hwmon/max31827.c new file mode 100644 index 0000000000..602f4e4f81 --- /dev/null +++ b/drivers/hwmon/max31827.c @@ -0,0 +1,466 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * max31827.c - Support for Maxim Low-Power Switch + * + * Copyright (c) 2023 Daniel Matyas <daniel.matyas@analog.com> + */ + +#include <linux/bitfield.h> +#include <linux/bitops.h> +#include <linux/delay.h> +#include <linux/hwmon.h> +#include <linux/i2c.h> +#include <linux/mutex.h> +#include <linux/regmap.h> + +#define MAX31827_T_REG 0x0 +#define MAX31827_CONFIGURATION_REG 0x2 +#define MAX31827_TH_REG 0x4 +#define MAX31827_TL_REG 0x6 +#define MAX31827_TH_HYST_REG 0x8 +#define MAX31827_TL_HYST_REG 0xA + +#define MAX31827_CONFIGURATION_1SHOT_MASK BIT(0) +#define MAX31827_CONFIGURATION_CNV_RATE_MASK GENMASK(3, 1) +#define MAX31827_CONFIGURATION_U_TEMP_STAT_MASK BIT(14) +#define MAX31827_CONFIGURATION_O_TEMP_STAT_MASK BIT(15) + +#define MAX31827_12_BIT_CNV_TIME 141 + +#define MAX31827_CNV_1_DIV_64_HZ 0x1 +#define MAX31827_CNV_1_DIV_32_HZ 0x2 +#define MAX31827_CNV_1_DIV_16_HZ 0x3 +#define MAX31827_CNV_1_DIV_4_HZ 0x4 +#define MAX31827_CNV_1_HZ 0x5 +#define MAX31827_CNV_4_HZ 0x6 +#define MAX31827_CNV_8_HZ 0x7 + +#define MAX31827_16_BIT_TO_M_DGR(x) (sign_extend32(x, 15) * 1000 / 16) +#define MAX31827_M_DGR_TO_16_BIT(x) (((x) << 4) / 1000) +#define MAX31827_DEVICE_ENABLE(x) ((x) ? 0xA : 0x0) + +struct max31827_state { + /* + * Prevent simultaneous access to the i2c client. + */ + struct mutex lock; + struct regmap *regmap; + bool enable; +}; + +static const struct regmap_config max31827_regmap = { + .reg_bits = 8, + .val_bits = 16, + .max_register = 0xA, +}; + +static int write_alarm_val(struct max31827_state *st, unsigned int reg, + long val) +{ + unsigned int cfg; + unsigned int tmp; + int ret; + + val = MAX31827_M_DGR_TO_16_BIT(val); + + /* + * Before the Temperature Threshold Alarm and Alarm Hysteresis Threshold + * register values are changed over I2C, the part must be in shutdown + * mode. + * + * Mutex is used to ensure, that some other process doesn't change the + * configuration register. + */ + mutex_lock(&st->lock); + + if (!st->enable) { + ret = regmap_write(st->regmap, reg, val); + goto unlock; + } + + ret = regmap_read(st->regmap, MAX31827_CONFIGURATION_REG, &cfg); + if (ret) + goto unlock; + + tmp = cfg & ~(MAX31827_CONFIGURATION_1SHOT_MASK | + MAX31827_CONFIGURATION_CNV_RATE_MASK); + ret = regmap_write(st->regmap, MAX31827_CONFIGURATION_REG, tmp); + if (ret) + goto unlock; + + ret = regmap_write(st->regmap, reg, val); + if (ret) + goto unlock; + + ret = regmap_write(st->regmap, MAX31827_CONFIGURATION_REG, cfg); + +unlock: + mutex_unlock(&st->lock); + return ret; +} + +static umode_t max31827_is_visible(const void *state, + enum hwmon_sensor_types type, u32 attr, + int channel) +{ + if (type == hwmon_temp) { + switch (attr) { + case hwmon_temp_enable: + case hwmon_temp_max: + case hwmon_temp_min: + case hwmon_temp_max_hyst: + case hwmon_temp_min_hyst: + return 0644; + case hwmon_temp_input: + case hwmon_temp_min_alarm: + case hwmon_temp_max_alarm: + return 0444; + default: + return 0; + } + } else if (type == hwmon_chip) { + if (attr == hwmon_chip_update_interval) + return 0644; + } + + return 0; +} + +static int max31827_read(struct device *dev, enum hwmon_sensor_types type, + u32 attr, int channel, long *val) +{ + struct max31827_state *st = dev_get_drvdata(dev); + unsigned int uval; + int ret = 0; + + switch (type) { + case hwmon_temp: + switch (attr) { + case hwmon_temp_enable: + ret = regmap_read(st->regmap, + MAX31827_CONFIGURATION_REG, &uval); + if (ret) + break; + + uval = FIELD_GET(MAX31827_CONFIGURATION_1SHOT_MASK | + MAX31827_CONFIGURATION_CNV_RATE_MASK, + uval); + *val = !!uval; + + break; + case hwmon_temp_input: + mutex_lock(&st->lock); + + if (!st->enable) { + /* + * This operation requires mutex protection, + * because the chip configuration should not + * be changed during the conversion process. + */ + + ret = regmap_update_bits(st->regmap, + MAX31827_CONFIGURATION_REG, + MAX31827_CONFIGURATION_1SHOT_MASK, + 1); + if (ret) { + mutex_unlock(&st->lock); + return ret; + } + + msleep(MAX31827_12_BIT_CNV_TIME); + } + ret = regmap_read(st->regmap, MAX31827_T_REG, &uval); + + mutex_unlock(&st->lock); + + if (ret) + break; + + *val = MAX31827_16_BIT_TO_M_DGR(uval); + + break; + case hwmon_temp_max: + ret = regmap_read(st->regmap, MAX31827_TH_REG, &uval); + if (ret) + break; + + *val = MAX31827_16_BIT_TO_M_DGR(uval); + break; + case hwmon_temp_max_hyst: + ret = regmap_read(st->regmap, MAX31827_TH_HYST_REG, + &uval); + if (ret) + break; + + *val = MAX31827_16_BIT_TO_M_DGR(uval); + break; + case hwmon_temp_max_alarm: + ret = regmap_read(st->regmap, + MAX31827_CONFIGURATION_REG, &uval); + if (ret) + break; + + *val = FIELD_GET(MAX31827_CONFIGURATION_O_TEMP_STAT_MASK, + uval); + break; + case hwmon_temp_min: + ret = regmap_read(st->regmap, MAX31827_TL_REG, &uval); + if (ret) + break; + + *val = MAX31827_16_BIT_TO_M_DGR(uval); + break; + case hwmon_temp_min_hyst: + ret = regmap_read(st->regmap, MAX31827_TL_HYST_REG, + &uval); + if (ret) + break; + + *val = MAX31827_16_BIT_TO_M_DGR(uval); + break; + case hwmon_temp_min_alarm: + ret = regmap_read(st->regmap, + MAX31827_CONFIGURATION_REG, &uval); + if (ret) + break; + + *val = FIELD_GET(MAX31827_CONFIGURATION_U_TEMP_STAT_MASK, + uval); + break; + default: + ret = -EOPNOTSUPP; + break; + } + + break; + + case hwmon_chip: + if (attr == hwmon_chip_update_interval) { + ret = regmap_read(st->regmap, + MAX31827_CONFIGURATION_REG, &uval); + if (ret) + break; + + uval = FIELD_GET(MAX31827_CONFIGURATION_CNV_RATE_MASK, + uval); + switch (uval) { + case MAX31827_CNV_1_DIV_64_HZ: + *val = 64000; + break; + case MAX31827_CNV_1_DIV_32_HZ: + *val = 32000; + break; + case MAX31827_CNV_1_DIV_16_HZ: + *val = 16000; + break; + case MAX31827_CNV_1_DIV_4_HZ: + *val = 4000; + break; + case MAX31827_CNV_1_HZ: + *val = 1000; + break; + case MAX31827_CNV_4_HZ: + *val = 250; + break; + case MAX31827_CNV_8_HZ: + *val = 125; + break; + default: + *val = 0; + break; + } + } + break; + + default: + ret = -EOPNOTSUPP; + break; + } + + return ret; +} + +static int max31827_write(struct device *dev, enum hwmon_sensor_types type, + u32 attr, int channel, long val) +{ + struct max31827_state *st = dev_get_drvdata(dev); + int ret; + + switch (type) { + case hwmon_temp: + switch (attr) { + case hwmon_temp_enable: + if (val >> 1) + return -EINVAL; + + mutex_lock(&st->lock); + /** + * The chip should not be enabled while a conversion is + * performed. Neither should the chip be enabled when + * the alarm values are changed. + */ + + st->enable = val; + + ret = regmap_update_bits(st->regmap, + MAX31827_CONFIGURATION_REG, + MAX31827_CONFIGURATION_1SHOT_MASK | + MAX31827_CONFIGURATION_CNV_RATE_MASK, + MAX31827_DEVICE_ENABLE(val)); + + mutex_unlock(&st->lock); + + return ret; + + case hwmon_temp_max: + return write_alarm_val(st, MAX31827_TH_REG, val); + + case hwmon_temp_max_hyst: + return write_alarm_val(st, MAX31827_TH_HYST_REG, val); + + case hwmon_temp_min: + return write_alarm_val(st, MAX31827_TL_REG, val); + + case hwmon_temp_min_hyst: + return write_alarm_val(st, MAX31827_TL_HYST_REG, val); + + default: + return -EOPNOTSUPP; + } + + case hwmon_chip: + if (attr == hwmon_chip_update_interval) { + if (!st->enable) + return -EINVAL; + + switch (val) { + case 125: + val = MAX31827_CNV_8_HZ; + break; + case 250: + val = MAX31827_CNV_4_HZ; + break; + case 1000: + val = MAX31827_CNV_1_HZ; + break; + case 4000: + val = MAX31827_CNV_1_DIV_4_HZ; + break; + case 16000: + val = MAX31827_CNV_1_DIV_16_HZ; + break; + case 32000: + val = MAX31827_CNV_1_DIV_32_HZ; + break; + case 64000: + val = MAX31827_CNV_1_DIV_64_HZ; + break; + default: + return -EINVAL; + } + + val = FIELD_PREP(MAX31827_CONFIGURATION_CNV_RATE_MASK, + val); + + return regmap_update_bits(st->regmap, + MAX31827_CONFIGURATION_REG, + MAX31827_CONFIGURATION_CNV_RATE_MASK, + val); + } + break; + + default: + return -EOPNOTSUPP; + } + + return -EOPNOTSUPP; +} + +static int max31827_init_client(struct max31827_state *st) +{ + st->enable = true; + + return regmap_update_bits(st->regmap, MAX31827_CONFIGURATION_REG, + MAX31827_CONFIGURATION_1SHOT_MASK | + MAX31827_CONFIGURATION_CNV_RATE_MASK, + MAX31827_DEVICE_ENABLE(1)); +} + +static const struct hwmon_channel_info *max31827_info[] = { + HWMON_CHANNEL_INFO(temp, HWMON_T_ENABLE | HWMON_T_INPUT | HWMON_T_MIN | + HWMON_T_MIN_HYST | HWMON_T_MIN_ALARM | + HWMON_T_MAX | HWMON_T_MAX_HYST | + HWMON_T_MAX_ALARM), + HWMON_CHANNEL_INFO(chip, HWMON_C_UPDATE_INTERVAL), + NULL, +}; + +static const struct hwmon_ops max31827_hwmon_ops = { + .is_visible = max31827_is_visible, + .read = max31827_read, + .write = max31827_write, +}; + +static const struct hwmon_chip_info max31827_chip_info = { + .ops = &max31827_hwmon_ops, + .info = max31827_info, +}; + +static int max31827_probe(struct i2c_client *client) +{ + struct device *dev = &client->dev; + struct device *hwmon_dev; + struct max31827_state *st; + int err; + + if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WORD_DATA)) + return -EOPNOTSUPP; + + st = devm_kzalloc(dev, sizeof(*st), GFP_KERNEL); + if (!st) + return -ENOMEM; + + mutex_init(&st->lock); + + st->regmap = devm_regmap_init_i2c(client, &max31827_regmap); + if (IS_ERR(st->regmap)) + return dev_err_probe(dev, PTR_ERR(st->regmap), + "Failed to allocate regmap.\n"); + + err = max31827_init_client(st); + if (err) + return err; + + hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, st, + &max31827_chip_info, + NULL); + + return PTR_ERR_OR_ZERO(hwmon_dev); +} + +static const struct i2c_device_id max31827_i2c_ids[] = { + { "max31827", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, max31827_i2c_ids); + +static const struct of_device_id max31827_of_match[] = { + { .compatible = "adi,max31827" }, + { } +}; +MODULE_DEVICE_TABLE(of, max31827_of_match); + +static struct i2c_driver max31827_driver = { + .class = I2C_CLASS_HWMON, + .driver = { + .name = "max31827", + .of_match_table = max31827_of_match, + }, + .probe = max31827_probe, + .id_table = max31827_i2c_ids, +}; +module_i2c_driver(max31827_driver); + +MODULE_AUTHOR("Daniel Matyas <daniel.matyas@analog.com>"); +MODULE_DESCRIPTION("Maxim MAX31827 low-power temperature switch driver"); +MODULE_LICENSE("GPL"); |