// SPDX-License-Identifier: GPL-2.0 /* * max31827.c - Support for Maxim Low-Power Switch * * Copyright (c) 2023 Daniel Matyas */ #include #include #include #include #include #include #include #include #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 140 #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) enum max31827_cnv { MAX31827_CNV_1_DIV_64_HZ = 1, MAX31827_CNV_1_DIV_32_HZ, MAX31827_CNV_1_DIV_16_HZ, MAX31827_CNV_1_DIV_4_HZ, MAX31827_CNV_1_HZ, MAX31827_CNV_4_HZ, MAX31827_CNV_8_HZ, }; static const u16 max31827_conversions[] = { [MAX31827_CNV_1_DIV_64_HZ] = 64000, [MAX31827_CNV_1_DIV_32_HZ] = 32000, [MAX31827_CNV_1_DIV_16_HZ] = 16000, [MAX31827_CNV_1_DIV_4_HZ] = 4000, [MAX31827_CNV_1_HZ] = 1000, [MAX31827_CNV_4_HZ] = 250, [MAX31827_CNV_8_HZ] = 125, }; 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 shutdown_write(struct max31827_state *st, unsigned int reg, unsigned int val) { unsigned int cfg; unsigned int cnv_rate; int ret; /* * 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; cnv_rate = MAX31827_CONFIGURATION_CNV_RATE_MASK & cfg; cfg = cfg & ~(MAX31827_CONFIGURATION_1SHOT_MASK | MAX31827_CONFIGURATION_CNV_RATE_MASK); ret = regmap_write(st->regmap, MAX31827_CONFIGURATION_REG, cfg); if (ret) goto unlock; ret = regmap_write(st->regmap, reg, val); if (ret) goto unlock; ret = regmap_update_bits(st->regmap, MAX31827_CONFIGURATION_REG, MAX31827_CONFIGURATION_CNV_RATE_MASK, cnv_rate); unlock: mutex_unlock(&st->lock); return ret; } static int write_alarm_val(struct max31827_state *st, unsigned int reg, long val) { val = MAX31827_M_DGR_TO_16_BIT(val); return shutdown_write(st, reg, val); } 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); *val = max31827_conversions[uval]; } 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 res = 1; 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; /* * Convert the desired conversion rate into register * bits. res is already initialized with 1. * * This was inspired by lm73 driver. */ while (res < ARRAY_SIZE(max31827_conversions) && val < max31827_conversions[res]) res++; if (res == ARRAY_SIZE(max31827_conversions) || val != max31827_conversions[res]) return -EINVAL; res = FIELD_PREP(MAX31827_CONFIGURATION_CNV_RATE_MASK, res); return regmap_update_bits(st->regmap, MAX31827_CONFIGURATION_REG, MAX31827_CONFIGURATION_CNV_RATE_MASK, res); } 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 = devm_regulator_get_enable(dev, "vref"); if (err) return dev_err_probe(dev, err, "failed to enable regulator\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 "); MODULE_DESCRIPTION("Maxim MAX31827 low-power temperature switch driver"); MODULE_LICENSE("GPL");