| Grant Coady | a0ef148 | 2005-06-03 10:05:19 +1000 | [diff] [blame] | 1 | Kernel driver adm9240 |
| 2 | ===================== |
| 3 | |
| 4 | Supported chips: |
| 5 | * Analog Devices ADM9240 |
| 6 | Prefix: 'adm9240' |
| 7 | Addresses scanned: I2C 0x2c - 0x2f |
| 8 | Datasheet: Publicly available at the Analog Devices website |
| 9 | http://www.analog.com/UploadedFiles/Data_Sheets/79857778ADM9240_0.pdf |
| 10 | |
| 11 | * Dallas Semiconductor DS1780 |
| 12 | Prefix: 'ds1780' |
| 13 | Addresses scanned: I2C 0x2c - 0x2f |
| 14 | Datasheet: Publicly available at the Dallas Semiconductor (Maxim) website |
| 15 | http://pdfserv.maxim-ic.com/en/ds/DS1780.pdf |
| 16 | |
| 17 | * National Semiconductor LM81 |
| 18 | Prefix: 'lm81' |
| 19 | Addresses scanned: I2C 0x2c - 0x2f |
| 20 | Datasheet: Publicly available at the National Semiconductor website |
| 21 | http://www.national.com/ds.cgi/LM/LM81.pdf |
| 22 | |
| 23 | Authors: |
| 24 | Frodo Looijaard <frodol@dds.nl>, |
| 25 | Philip Edelbrock <phil@netroedge.com>, |
| 26 | Michiel Rook <michiel@grendelproject.nl>, |
| 27 | Grant Coady <gcoady@gmail.com> with guidance |
| 28 | from Jean Delvare <khali@linux-fr.org> |
| 29 | |
| 30 | Interface |
| 31 | --------- |
| 32 | The I2C addresses listed above assume BIOS has not changed the |
| 33 | chip MSB 5-bit address. Each chip reports a unique manufacturer |
| 34 | identification code as well as the chip revision/stepping level. |
| 35 | |
| 36 | Description |
| 37 | ----------- |
| 38 | [From ADM9240] The ADM9240 is a complete system hardware monitor for |
| 39 | microprocessor-based systems, providing measurement and limit comparison |
| 40 | of up to four power supplies and two processor core voltages, plus |
| 41 | temperature, two fan speeds and chassis intrusion. Measured values can |
| 42 | be read out via an I2C-compatible serial System Management Bus, and values |
| 43 | for limit comparisons can be programmed in over the same serial bus. The |
| 44 | high speed successive approximation ADC allows frequent sampling of all |
| 45 | analog channels to ensure a fast interrupt response to any out-of-limit |
| 46 | measurement. |
| 47 | |
| 48 | The ADM9240, DS1780 and LM81 are register compatible, the following |
| 49 | details are common to the three chips. Chip differences are described |
| 50 | after this section. |
| 51 | |
| 52 | |
| 53 | Measurements |
| 54 | ------------ |
| 55 | The measurement cycle |
| 56 | |
| 57 | The adm9240 driver will take a measurement reading no faster than once |
| 58 | each two seconds. User-space may read sysfs interface faster than the |
| 59 | measurement update rate and will receive cached data from the most |
| 60 | recent measurement. |
| 61 | |
| 62 | ADM9240 has a very fast 320us temperature and voltage measurement cycle |
| 63 | with independent fan speed measurement cycles counting alternating rising |
| 64 | edges of the fan tacho inputs. |
| 65 | |
| 66 | DS1780 measurement cycle is about once per second including fan speed. |
| 67 | |
| 68 | LM81 measurement cycle is about once per 400ms including fan speed. |
| 69 | The LM81 12-bit extended temperature measurement mode is not supported. |
| 70 | |
| 71 | Temperature |
| 72 | ----------- |
| 73 | On chip temperature is reported as degrees Celsius as 9-bit signed data |
| 74 | with resolution of 0.5 degrees Celsius. High and low temperature limits |
| 75 | are 8-bit signed data with resolution of one degree Celsius. |
| 76 | |
| 77 | Temperature alarm is asserted once the temperature exceeds the high limit, |
| 78 | and is cleared when the temperature falls below the temp1_max_hyst value. |
| 79 | |
| 80 | Fan Speed |
| 81 | --------- |
| 82 | Two fan tacho inputs are provided, the ADM9240 gates an internal 22.5kHz |
| 83 | clock via a divider to an 8-bit counter. Fan speed (rpm) is calculated by: |
| 84 | |
| 85 | rpm = (22500 * 60) / (count * divider) |
| 86 | |
| 87 | Automatic fan clock divider |
| 88 | |
| 89 | * User sets 0 to fan_min limit |
| 90 | - low speed alarm is disabled |
| 91 | - fan clock divider not changed |
| 92 | - auto fan clock adjuster enabled for valid fan speed reading |
| 93 | |
| 94 | * User sets fan_min limit too low |
| 95 | - low speed alarm is enabled |
| 96 | - fan clock divider set to max |
| 97 | - fan_min set to register value 254 which corresponds |
| 98 | to 664 rpm on adm9240 |
| 99 | - low speed alarm will be asserted if fan speed is |
| 100 | less than minimum measurable speed |
| 101 | - auto fan clock adjuster disabled |
| 102 | |
| 103 | * User sets reasonable fan speed |
| 104 | - low speed alarm is enabled |
| 105 | - fan clock divider set to suit fan_min |
| 106 | - auto fan clock adjuster enabled: adjusts fan_min |
| 107 | |
| 108 | * User sets unreasonably high low fan speed limit |
| 109 | - resolution of the low speed limit may be reduced |
| 110 | - alarm will be asserted |
| 111 | - auto fan clock adjuster enabled: adjusts fan_min |
| 112 | |
| 113 | * fan speed may be displayed as zero until the auto fan clock divider |
| 114 | adjuster brings fan speed clock divider back into chip measurement |
| 115 | range, this will occur within a few measurement cycles. |
| 116 | |
| 117 | Analog Output |
| 118 | ------------- |
| 119 | An analog output provides a 0 to 1.25 volt signal intended for an external |
| 120 | fan speed amplifier circuit. The analog output is set to maximum value on |
| 121 | power up or reset. This doesn't do much on the test Intel SE440BX-2. |
| 122 | |
| 123 | Voltage Monitor |
| 124 | |
| 125 | Voltage (IN) measurement is internally scaled: |
| 126 | |
| 127 | nr label nominal maximum resolution |
| 128 | mV mV mV |
| 129 | 0 +2.5V 2500 3320 13.0 |
| 130 | 1 Vccp1 2700 3600 14.1 |
| 131 | 2 +3.3V 3300 4380 17.2 |
| 132 | 3 +5V 5000 6640 26.0 |
| 133 | 4 +12V 12000 15940 62.5 |
| 134 | 5 Vccp2 2700 3600 14.1 |
| 135 | |
| 136 | The reading is an unsigned 8-bit value, nominal voltage measurement is |
| 137 | represented by a reading of 192, being 3/4 of the measurement range. |
| 138 | |
| 139 | An alarm is asserted for any voltage going below or above the set limits. |
| 140 | |
| 141 | The driver reports and accepts voltage limits scaled to the above table. |
| 142 | |
| 143 | VID Monitor |
| 144 | ----------- |
| 145 | The chip has five inputs to read the 5-bit VID and reports the mV value |
| 146 | based on detected CPU type. |
| 147 | |
| 148 | Chassis Intrusion |
| 149 | ----------------- |
| 150 | An alarm is asserted when the CI pin goes active high. The ADM9240 |
| 151 | Datasheet has an example of an external temperature sensor driving |
| 152 | this pin. On an Intel SE440BX-2 the Chassis Intrusion header is |
| 153 | connected to a normally open switch. |
| 154 | |
| 155 | The ADM9240 provides an internal open drain on this line, and may output |
| 156 | a 20 ms active low pulse to reset an external Chassis Intrusion latch. |
| 157 | |
| 158 | Clear the CI latch by writing value 1 to the sysfs chassis_clear file. |
| 159 | |
| 160 | Alarm flags reported as 16-bit word |
| 161 | |
| 162 | bit label comment |
| 163 | --- ------------- -------------------------- |
| 164 | 0 +2.5 V_Error high or low limit exceeded |
| 165 | 1 VCCP_Error high or low limit exceeded |
| 166 | 2 +3.3 V_Error high or low limit exceeded |
| 167 | 3 +5 V_Error high or low limit exceeded |
| 168 | 4 Temp_Error temperature error |
| 169 | 6 FAN1_Error fan low limit exceeded |
| 170 | 7 FAN2_Error fan low limit exceeded |
| 171 | 8 +12 V_Error high or low limit exceeded |
| 172 | 9 VCCP2_Error high or low limit exceeded |
| 173 | 12 Chassis_Error CI pin went high |
| 174 | |
| 175 | Remaining bits are reserved and thus undefined. It is important to note |
| 176 | that alarm bits may be cleared on read, user-space may latch alarms and |
| 177 | provide the end-user with a method to clear alarm memory. |