| Mauro Carvalho Chehab | ccf988b | 2019-07-26 09:51:16 -0300 | [diff] [blame] | 1 | ============================== |
| Wolfram Sang | 59d3d60 | 2020-06-28 20:54:26 +0200 | [diff] [blame] | 2 | Linux I2C slave EEPROM backend |
| Wolfram Sang | d0c892f | 2015-03-23 09:26:38 +0100 | [diff] [blame] | 3 | ============================== |
| 4 | |
| Wolfram Sang | 59d3d60 | 2020-06-28 20:54:26 +0200 | [diff] [blame] | 5 | by Wolfram Sang <wsa@sang-engineering.com> in 2014-20 |
| Wolfram Sang | d0c892f | 2015-03-23 09:26:38 +0100 | [diff] [blame] | 6 | |
| Wolfram Sang | 59d3d60 | 2020-06-28 20:54:26 +0200 | [diff] [blame] | 7 | This backend simulates an EEPROM on the connected I2C bus. Its memory contents |
| 8 | can be accessed from userspace via this file located in sysfs:: |
| Wolfram Sang | d0c892f | 2015-03-23 09:26:38 +0100 | [diff] [blame] | 9 | |
| Masanari Iida | 2e049d6 | 2016-02-02 20:41:25 +0900 | [diff] [blame] | 10 | /sys/bus/i2c/devices/<device-directory>/slave-eeprom |
| Wolfram Sang | d0c892f | 2015-03-23 09:26:38 +0100 | [diff] [blame] | 11 | |
| Wolfram Sang | 59d3d60 | 2020-06-28 20:54:26 +0200 | [diff] [blame] | 12 | The following types are available: 24c02, 24c32, 24c64, and 24c512. Read-only |
| 13 | variants are also supported. The name needed for instantiating has the form |
| 14 | 'slave-<type>[ro]'. Examples follow: |
| 15 | |
| 16 | 24c02, read/write, address 0x64: |
| 17 | # echo slave-24c02 0x1064 > /sys/bus/i2c/devices/i2c-1/new_device |
| 18 | |
| 19 | 24c512, read-only, address 0x42: |
| 20 | # echo slave-24c512ro 0x1042 > /sys/bus/i2c/devices/i2c-1/new_device |
| 21 | |
| 22 | You can also preload data during boot if a device-property named |
| 23 | 'firmware-name' contains a valid filename (DT or ACPI only). |
| 24 | |
| Wolfram Sang | d0c892f | 2015-03-23 09:26:38 +0100 | [diff] [blame] | 25 | As of 2015, Linux doesn't support poll on binary sysfs files, so there is no |
| Masanari Iida | 2e049d6 | 2016-02-02 20:41:25 +0900 | [diff] [blame] | 26 | notification when another master changed the content. |