From 29a9ac6414abd634e7f460a250b70a452d9a04b9 Mon Sep 17 00:00:00 2001 From: Daniel Matyas Date: Tue, 31 Oct 2023 20:21:57 +0200 Subject: [PATCH] hwmon: (max31827) Add custom attribute for resolution Added custom channel-specific (temp1) attribute for resolution. The wait time for a conversion in one-shot mode (enable = 0) depends on the resolution. When resolution is 12-bit, the conversion time is 140ms, but the minimum update_interval is 125ms. Handled this problem by waiting an additional 15ms (125ms + 15ms = 140ms). Added 'mask' parameter to the shutdown_write() function. Now it can either write or update bits, depending on the value of mask. This is needed, because for alarms a write is necessary, but for resolution only the resolution bits should be updated. Signed-off-by: Daniel Matyas Link: https://lore.kernel.org/r/20231031182158.124608-5-daniel.matyas@analog.com Signed-off-by: Guenter Roeck --- Documentation/hwmon/max31827.rst | 29 ++++++-- drivers/hwmon/max31827.c | 122 ++++++++++++++++++++++++++++--- 2 files changed, 134 insertions(+), 17 deletions(-) diff --git a/Documentation/hwmon/max31827.rst b/Documentation/hwmon/max31827.rst index a8bbfb85dd02..44ab9dc064cb 100644 --- a/Documentation/hwmon/max31827.rst +++ b/Documentation/hwmon/max31827.rst @@ -90,11 +90,28 @@ the data sheet are: Enabling the device when it is already enabled has the side effect of setting the conversion frequency to 1 conv/s. The conversion time varies depending on -the resolution. The conversion time doubles with every bit of increased -resolution. For 10 bit resolution 35ms are needed, while for 12 bit resolution -(default) 140ms. When chip is in shutdown mode and a read operation is -requested, one-shot is triggered, the device waits for 140 (conversion time) ms, -and only after that is the temperature value register read. +the resolution. + +The conversion time doubles with every bit of increased resolution. The +available resolutions are: + +- 8 bit -> 8.75 ms conversion time +- 9 bit -> 17.5 ms conversion time +- 10 bit -> 35 ms conversion time +- 12 bit (default) -> 140 ms conversion time + +There is a temp1_resolution attribute which indicates the unit change in the +input temperature in milli-degrees C. + +- 1000 mC -> 8 bit +- 500 mC -> 9 bit +- 250 mC -> 10 bit +- 62 mC -> 12 bit (default) - actually this is 62.5, but the fil returns 62 + +When chip is in shutdown mode and a read operation is requested, one-shot is +triggered, the device waits for ms, and only after that is +the temperature value register read. Note that the conversion times are rounded +up to the nearest possible integer. The LSB of the temperature values is 0.0625 degrees Celsius, but the values of the temperatures are displayed in milli-degrees. This means, that some data is @@ -117,4 +134,4 @@ corresponding status bits. Notes ----- -PEC and resolution are not implemented. +PEC is not implemented. diff --git a/drivers/hwmon/max31827.c b/drivers/hwmon/max31827.c index 6b7bfacf6f0a..4a8c3e37c5d3 100644 --- a/drivers/hwmon/max31827.c +++ b/drivers/hwmon/max31827.c @@ -37,6 +37,9 @@ #define MAX31827_FLT_Q_1 0x0 #define MAX31827_FLT_Q_4 0x2 +#define MAX31827_8_BIT_CNV_TIME 9 +#define MAX31827_9_BIT_CNV_TIME 18 +#define MAX31827_10_BIT_CNV_TIME 35 #define MAX31827_12_BIT_CNV_TIME 140 #define MAX31827_16_BIT_TO_M_DGR(x) (sign_extend32(x, 15) * 1000 / 16) @@ -65,6 +68,27 @@ static const u16 max31827_conversions[] = { [MAX31827_CNV_8_HZ] = 125, }; +enum max31827_resolution { + MAX31827_RES_8_BIT = 0, + MAX31827_RES_9_BIT, + MAX31827_RES_10_BIT, + MAX31827_RES_12_BIT, +}; + +static const u16 max31827_resolutions[] = { + [MAX31827_RES_8_BIT] = 1000, + [MAX31827_RES_9_BIT] = 500, + [MAX31827_RES_10_BIT] = 250, + [MAX31827_RES_12_BIT] = 62, +}; + +static const u16 max31827_conv_times[] = { + [MAX31827_RES_8_BIT] = MAX31827_8_BIT_CNV_TIME, + [MAX31827_RES_9_BIT] = MAX31827_9_BIT_CNV_TIME, + [MAX31827_RES_10_BIT] = MAX31827_10_BIT_CNV_TIME, + [MAX31827_RES_12_BIT] = MAX31827_12_BIT_CNV_TIME, +}; + struct max31827_state { /* * Prevent simultaneous access to the i2c client. @@ -72,6 +96,8 @@ struct max31827_state { struct mutex lock; struct regmap *regmap; bool enable; + unsigned int resolution; + unsigned int update_interval; }; static const struct regmap_config max31827_regmap = { @@ -88,9 +114,9 @@ static int shutdown_write(struct max31827_state *st, unsigned int reg, int ret; /* - * Before the Temperature Threshold Alarm and Alarm Hysteresis Threshold - * register values are changed over I2C, the part must be in shutdown - * mode. + * Before the Temperature Threshold Alarm, Alarm Hysteresis Threshold + * and Resolution bits from Configuration register 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. @@ -208,9 +234,18 @@ static int max31827_read(struct device *dev, enum hwmon_sensor_types type, mutex_unlock(&st->lock); return ret; } - - msleep(MAX31827_12_BIT_CNV_TIME); + msleep(max31827_conv_times[st->resolution]); } + + /* + * For 12-bit resolution the conversion time is 140 ms, + * thus an additional 15 ms is needed to complete the + * conversion: 125 ms + 15 ms = 140 ms + */ + if (max31827_resolutions[st->resolution] == 12 && + st->update_interval == 125) + usleep_range(15000, 20000); + ret = regmap_read(st->regmap, MAX31827_T_REG, &uval); mutex_unlock(&st->lock); @@ -367,10 +402,14 @@ static int max31827_write(struct device *dev, enum hwmon_sensor_types type, res = FIELD_PREP(MAX31827_CONFIGURATION_CNV_RATE_MASK, res); - return regmap_update_bits(st->regmap, - MAX31827_CONFIGURATION_REG, - MAX31827_CONFIGURATION_CNV_RATE_MASK, - res); + ret = regmap_update_bits(st->regmap, + MAX31827_CONFIGURATION_REG, + MAX31827_CONFIGURATION_CNV_RATE_MASK, + res); + if (ret) + return ret; + + st->update_interval = val; } break; @@ -378,9 +417,70 @@ static int max31827_write(struct device *dev, enum hwmon_sensor_types type, return -EOPNOTSUPP; } - return -EOPNOTSUPP; + return 0; } +static ssize_t temp1_resolution_show(struct device *dev, + struct device_attribute *devattr, + char *buf) +{ + struct max31827_state *st = dev_get_drvdata(dev); + unsigned int val; + int ret; + + ret = regmap_read(st->regmap, MAX31827_CONFIGURATION_REG, &val); + if (ret) + return ret; + + val = FIELD_GET(MAX31827_CONFIGURATION_RESOLUTION_MASK, val); + + return scnprintf(buf, PAGE_SIZE, "%u\n", max31827_resolutions[val]); +} + +static ssize_t temp1_resolution_store(struct device *dev, + struct device_attribute *devattr, + const char *buf, size_t count) +{ + struct max31827_state *st = dev_get_drvdata(dev); + unsigned int idx = 0; + unsigned int val; + int ret; + + ret = kstrtouint(buf, 10, &val); + if (ret) + return ret; + + /* + * Convert the desired resolution into register + * bits. idx is already initialized with 0. + * + * This was inspired by lm73 driver. + */ + while (idx < ARRAY_SIZE(max31827_resolutions) && + val < max31827_resolutions[idx]) + idx++; + + if (idx == ARRAY_SIZE(max31827_resolutions)) + idx = ARRAY_SIZE(max31827_resolutions) - 1; + + st->resolution = idx; + + ret = shutdown_write(st, MAX31827_CONFIGURATION_REG, + MAX31827_CONFIGURATION_RESOLUTION_MASK, + FIELD_PREP(MAX31827_CONFIGURATION_RESOLUTION_MASK, + idx)); + + return ret ? ret : count; +} + +static DEVICE_ATTR_RW(temp1_resolution); + +static struct attribute *max31827_attrs[] = { + &dev_attr_temp1_resolution.attr, + NULL +}; +ATTRIBUTE_GROUPS(max31827); + static const struct i2c_device_id max31827_i2c_ids[] = { { "max31827", max31827 }, { "max31828", max31828 }, @@ -529,7 +629,7 @@ static int max31827_probe(struct i2c_client *client) hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, st, &max31827_chip_info, - NULL); + max31827_groups); return PTR_ERR_OR_ZERO(hwmon_dev); }