| README for adm1278 hwmon driver |
| ================================== |
| Yi Li <shliyi@cn.ibm.com> |
| |
| |
| This is a temporary kernel patch to enable hwmon driver for adm1278 chip on Barreleye. |
| When this patch is merged into linux kernel, this patch will be removed from openbmc. |
| |
| The adm1278 driver is created according to datasheet: |
| http://www.analog.com/media/en/technical-documentation/data-sheets/ADM1278.pdf |
| |
| The patch heavily re-used adm1278 enabling code from: https://github.com/facebook/openbmc/blob/master/meta-aspeed/recipes-kernel/linux/files/patch-2.6.28.9/0000-linux-openbmc.patch. |
| |
| This patch has been tested on barreleye, by following these steps: |
| |
| 1) There are 3 adm1278 devices on Barreleye |
| |
| I2C5: P12v_a for CPU0 |
| I2C6: P12v_b for CPU1 |
| I2C7: P12v_c for HDD and IO Board |
| |
| 2) adm1278 driver is based on adm1275.c, which depends on pmbus. This patch builds |
| adm1275 and pmbus into kernel. |
| |
| 3) When kernel booted, initialize the adm1278 devices: |
| |
| root@barreleye:~# echo adm1278 0x10 > /sys/class/i2c-adapter/i2c-4/new_device |
| root@barreleye:~# echo adm1278 0x10 > /sys/class/i2c-adapter/i2c-5/new_device |
| root@barreleye:~# echo adm1278 0x10 > /sys/class/i2c-adapter/i2c-6/new_device |
| |
| There will be three new hwmon sysfs entries created: |
| |
| root@barreleye:~# ls /sys/class/hwmon/hwmon3/ |
| curr1_highest in1_highest in1_reset_history in2_min_alarm power1_label temp1_input |
| curr1_input in1_input in2_highest in2_reset_history power1_max temp1_max |
| curr1_label in1_label in2_input name power1_reset_history temp1_max_alarm |
| curr1_max in1_max in2_label power/ subsystem/ temp1_reset_history |
| curr1_max_alarm in1_max_alarm in2_max power1_alarm temp1_crit uevent |
| curr1_reset_history in1_min in2_max_alarm power1_input temp1_crit_alarm |
| device/ in1_min_alarm in2_min power1_input_highest temp1_highest |
| root@barreleye:~# ls /sys/class/hwmon/hwmon4/ |
| curr1_highest in1_highest in1_reset_history in2_min_alarm power1_label temp1_input |
| curr1_input in1_input in2_highest in2_reset_history power1_max temp1_max |
| curr1_label in1_label in2_input name power1_reset_history temp1_max_alarm |
| curr1_max in1_max in2_label power/ subsystem/ temp1_reset_history |
| curr1_max_alarm in1_max_alarm in2_max power1_alarm temp1_crit uevent |
| curr1_reset_history in1_min in2_max_alarm power1_input temp1_crit_alarm |
| device/ in1_min_alarm in2_min power1_input_highest temp1_highest |
| root@barreleye:~# ls /sys/class/hwmon/hwmon5/ |
| curr1_highest in1_highest in1_reset_history in2_min_alarm power1_label temp1_input |
| curr1_input in1_input in2_highest in2_reset_history power1_max temp1_max |
| curr1_label in1_label in2_input name power1_reset_history temp1_max_alarm |
| curr1_max in1_max in2_label power/ subsystem/ temp1_reset_history |
| curr1_max_alarm in1_max_alarm in2_max power1_alarm temp1_crit uevent |
| curr1_reset_history in1_min in2_max_alarm power1_input temp1_crit_alarm |
| device/ in1_min_alarm in2_min power1_input_highest temp1_highest |
| |
| 4) For details of what each hwmon sysfs attributes mean, please refer to: |
| https://www.kernel.org/doc/Documentation/hwmon/pmbus |
| For short, 'curr1_*' refers to 'IOUT', 'in1_*' refers to 'vin', 'in2_*' refers to 'vout', 'power1_*' refers to 'input power', |
| 'temp1_*' for 'temperature'. |
| |
| 5) Remaining issue: |
| |
| 5.1) Currently, i2c_aspeed driver does not handle "i2c_smbus_read_block_data()" correctly. So this patch has to bypass some detection code. |
| We need to fix this issue when the patch is merged to kernel. |
| 5.2) According to adm1278 datasheet, there is a sense resistor used to measure power and current. The resistor will affect conversion between |
| adm1278 register value to real-world value for current and power. I am not very sure about the resistor value. So using 1 mili-ohms (or 1000 micro-ohms) as default value. When build the adm1275 driver as kernel module, we can set this resistor value by: |
| |
| # insmod adm1275.ko r_sense=500 |
| |
| This will set the 'sense resistor' to 500 micro-ohms. |
| 5.3) Some of the sensor value, e.g, 'temp1_input' seems not reasonable, e.g: |
| |
| root@barreleye:~# cat /sys/class/hwmon/hwmon4/temp1_input |
| -270952 |
| |
| Need further check on that. |