diff options
Diffstat (limited to 'Documentation/hwmon')
| -rw-r--r-- | Documentation/hwmon/ds1621 | 144 | ||||
| -rw-r--r-- | Documentation/hwmon/g762 | 65 | ||||
| -rw-r--r-- | Documentation/hwmon/ina2xx | 4 |
3 files changed, 202 insertions, 11 deletions
diff --git a/Documentation/hwmon/ds1621 b/Documentation/hwmon/ds1621 index 5e97f333c4d..896cdc972ca 100644 --- a/Documentation/hwmon/ds1621 +++ b/Documentation/hwmon/ds1621 @@ -2,16 +2,30 @@ Kernel driver ds1621 ==================== Supported chips: - * Dallas Semiconductor DS1621 + * Dallas Semiconductor / Maxim Integrated DS1621 Prefix: 'ds1621' - Addresses scanned: I2C 0x48 - 0x4f - Datasheet: Publicly available at the Dallas Semiconductor website - http://www.dalsemi.com/ + Addresses scanned: none + Datasheet: Publicly available from www.maximintegrated.com + * Dallas Semiconductor DS1625 - Prefix: 'ds1621' - Addresses scanned: I2C 0x48 - 0x4f - Datasheet: Publicly available at the Dallas Semiconductor website - http://www.dalsemi.com/ + Prefix: 'ds1625' + Addresses scanned: none + Datasheet: Publicly available from www.datasheetarchive.com + + * Maxim Integrated DS1631 + Prefix: 'ds1631' + Addresses scanned: none + Datasheet: Publicly available from www.maximintegrated.com + + * Maxim Integrated DS1721 + Prefix: 'ds1721' + Addresses scanned: none + Datasheet: Publicly available from www.maximintegrated.com + + * Maxim Integrated DS1731 + Prefix: 'ds1731' + Addresses scanned: none + Datasheet: Publicly available from www.maximintegrated.com Authors: Christian W. Zuckschwerdt <zany@triq.net> @@ -59,5 +73,115 @@ any of the limits have ever been met or exceeded since last power-up or reset. Be aware: When testing, it showed that the status of Tout can change with neither of the alarms set. -Temperature conversion of the DS1621 takes up to 1000ms; internal access to -non-volatile registers may last for 10ms or below. +Since there is no version or vendor identification register, there is +no unique identification for these devices. Therefore, explicit device +instantiation is required for correct device identification and functionality +(one device per address in this address range: 0x48..0x4f). + +The DS1625 is pin compatible and functionally equivalent with the DS1621, +but the DS1621 is meant to replace it. The DS1631, DS1721, and DS1731 are +also pin compatible with the DS1621 and provide multi-resolution support. + +Additionally, the DS1721 data sheet says the temperature flags (THF and TLF) +are used internally, however, these flags do get set and cleared as the actual +temperature crosses the min or max settings (which by default are set to 75 +and 80 degrees respectively). + +Temperature Conversion: +----------------------- +DS1621 - 750ms (older devices may take up to 1000ms) +DS1625 - 500ms +DS1631 - 93ms..750ms for 9..12 bits resolution, respectively. +DS1721 - 93ms..750ms for 9..12 bits resolution, respectively. +DS1731 - 93ms..750ms for 9..12 bits resolution, respectively. + +Note: +On the DS1621, internal access to non-volatile registers may last for 10ms +or less (unverified on the other devices). + +Temperature Accuracy: +--------------------- +DS1621: +/- 0.5 degree Celsius (from 0 to +70 degrees) +DS1625: +/- 0.5 degree Celsius (from 0 to +70 degrees) +DS1631: +/- 0.5 degree Celsius (from 0 to +70 degrees) +DS1721: +/- 1.0 degree Celsius (from -10 to +85 degrees) +DS1731: +/- 1.0 degree Celsius (from -10 to +85 degrees) + +Note: +Please refer to the device datasheets for accuracy at other temperatures. + +Temperature Resolution: +----------------------- +As mentioned above, the DS1631, DS1721, and DS1731 provide multi-resolution +support, which is achieved via the R0 and R1 config register bits, where: + +R0..R1 +------ + 0 0 => 9 bits, 0.5 degrees Celcius + 1 0 => 10 bits, 0.25 degrees Celcius + 0 1 => 11 bits, 0.125 degrees Celcius + 1 1 => 12 bits, 0.0625 degrees Celcius + +Note: +At initial device power-on, the default resolution is set to 12-bits. + +The resolution mode for the DS1631, DS1721, or DS1731 can be changed from +userspace, via the device 'update_interval' sysfs attribute. This attribute +will normalize the range of input values to the device maximum resolution +values defined in the datasheet as follows: + +Resolution Conversion Time Input Range + (C/LSB) (msec) (msec) +------------------------------------------------ +0.5 93.75 0....94 +0.25 187.5 95...187 +0.125 375 188..375 +0.0625 750 376..infinity +------------------------------------------------ + +The following examples show how the 'update_interval' attribute can be +used to change the conversion time: + +$ cat update_interval +750 +$ cat temp1_input +22062 +$ +$ echo 300 > update_interval +$ cat update_interval +375 +$ cat temp1_input +22125 +$ +$ echo 150 > update_interval +$ cat update_interval +188 +$ cat temp1_input +22250 +$ +$ echo 1 > update_interval +$ cat update_interval +94 +$ cat temp1_input +22000 +$ +$ echo 1000 > update_interval +$ cat update_interval +750 +$ cat temp1_input +22062 +$ + +As shown, the ds1621 driver automatically adjusts the 'update_interval' +user input, via a step function. Reading back the 'update_interval' value +after a write operation provides the conversion time used by the device. + +Mathematically, the resolution can be derived from the conversion time +via the following function: + + g(x) = 0.5 * [minimum_conversion_time/x] + +where: + -> 'x' = the output from 'update_interval' + -> 'g(x)' = the resolution in degrees C per LSB. + -> 93.75ms = minimum conversion time diff --git a/Documentation/hwmon/g762 b/Documentation/hwmon/g762 new file mode 100644 index 00000000000..923db9c5b5b --- /dev/null +++ b/Documentation/hwmon/g762 @@ -0,0 +1,65 @@ +Kernel driver g762 +================== + +The GMT G762 Fan Speed PWM Controller is connected directly to a fan +and performs closed-loop or open-loop control of the fan speed. Two +modes - PWM or DC - are supported by the device. + +For additional information, a detailed datasheet is available at +http://natisbad.org/NAS/ref/GMT_EDS-762_763-080710-0.2.pdf. sysfs +bindings are described in Documentation/hwmon/sysfs-interface. + +The following entries are available to the user in a subdirectory of +/sys/bus/i2c/drivers/g762/ to control the operation of the device. +This can be done manually using the following entries but is usually +done via a userland daemon like fancontrol. + +Note that those entries do not provide ways to setup the specific +hardware characteristics of the system (reference clock, pulses per +fan revolution, ...); Those can be modified via devicetree bindings +documented in Documentation/devicetree/bindings/hwmon/g762.txt or +using a specific platform_data structure in board initialization +file (see include/linux/platform_data/g762.h). + + fan1_target: set desired fan speed. This only makes sense in closed-loop + fan speed control (i.e. when pwm1_enable is set to 2). + + fan1_input: provide current fan rotation value in RPM as reported by + the fan to the device. + + fan1_div: fan clock divisor. Supported value are 1, 2, 4 and 8. + + fan1_pulses: number of pulses per fan revolution. Supported values + are 2 and 4. + + fan1_fault: reports fan failure, i.e. no transition on fan gear pin for + about 0.7s (if the fan is not voluntarily set off). + + fan1_alarm: in closed-loop control mode, if fan RPM value is 25% out + of the programmed value for over 6 seconds 'fan1_alarm' is + set to 1. + + pwm1_enable: set current fan speed control mode i.e. 1 for manual fan + speed control (open-loop) via pwm1 described below, 2 for + automatic fan speed control (closed-loop) via fan1_target + above. + + pwm1_mode: set or get fan driving mode: 1 for PWM mode, 0 for DC mode. + + pwm1: get or set PWM fan control value in open-loop mode. This is an + integer value between 0 and 255. 0 stops the fan, 255 makes + it run at full speed. + +Both in PWM mode ('pwm1_mode' set to 1) and DC mode ('pwm1_mode' set to 0), +when current fan speed control mode is open-loop ('pwm1_enable' set to 1), +the fan speed is programmed by setting a value between 0 and 255 via 'pwm1' +entry (0 stops the fan, 255 makes it run at full speed). In closed-loop mode +('pwm1_enable' set to 2), the expected rotation speed in RPM can be passed to +the chip via 'fan1_target'. In closed-loop mode, the target speed is compared +with current speed (available via 'fan1_input') by the device and a feedback +is performed to match that target value. The fan speed value is computed +based on the parameters associated with the physical characteristics of the +system: a reference clock source frequency, a number of pulses per fan +revolution, etc. + +Note that the driver will update its values at most once per second. diff --git a/Documentation/hwmon/ina2xx b/Documentation/hwmon/ina2xx index 03444f9d833..4223c2d3b50 100644 --- a/Documentation/hwmon/ina2xx +++ b/Documentation/hwmon/ina2xx @@ -44,4 +44,6 @@ The INA226 monitors both a shunt voltage drop and bus supply voltage. The INA230 is a high or low side current shunt and power monitor with an I2C interface. The INA230 monitors both a shunt voltage drop and bus supply voltage. -The shunt value in micro-ohms can be set via platform data. +The shunt value in micro-ohms can be set via platform data or device tree. +Please refer to the Documentation/devicetree/bindings/i2c/ina2xx.txt for bindings +if the device tree is used. |