| Mauro Carvalho Chehab | e9bb627 | 2019-07-31 17:08:53 -0300 | [diff] [blame] | 1 | ======================= |
| Scott Alfter | 94859308 | 2014-06-17 20:42:05 +0000 | [diff] [blame] | 2 | w1_ds2406 kernel driver |
| 3 | ======================= |
| 4 | |
| 5 | Supported chips: |
| Mauro Carvalho Chehab | e9bb627 | 2019-07-31 17:08:53 -0300 | [diff] [blame] | 6 | |
| Scott Alfter | 94859308 | 2014-06-17 20:42:05 +0000 | [diff] [blame] | 7 | * Maxim DS2406 (and other family 0x12) addressable switches |
| 8 | |
| 9 | Author: Scott Alfter <scott@alfter.us> |
| 10 | |
| 11 | Description |
| 12 | ----------- |
| 13 | |
| Mauro Carvalho Chehab | e9bb627 | 2019-07-31 17:08:53 -0300 | [diff] [blame] | 14 | The w1_ds2406 driver allows connected devices to be switched on and off. |
| Scott Alfter | 94859308 | 2014-06-17 20:42:05 +0000 | [diff] [blame] | 15 | These chips also provide 128 bytes of OTP EPROM, but reading/writing it is |
| 16 | not supported. In TSOC-6 form, the DS2406 provides two switch outputs and |
| 17 | can be provided with power on a dedicated input. In TO-92 form, it provides |
| 18 | one output and uses parasitic power only. |
| 19 | |
| 20 | The driver provides two sysfs files. state is readable; it gives the |
| 21 | current state of each switch, with PIO A in bit 0 and PIO B in bit 1. The |
| 22 | driver ORs this state with 0x30, so shell scripts get an ASCII 0/1/2/3 to |
| 23 | work with. output is writable; bits 0 and 1 control PIO A and B, |
| 24 | respectively. Bits 2-7 are ignored, so it's safe to write ASCII data. |
| 25 | |
| 26 | CRCs are checked on read and write. Failed checks cause an I/O error to be |
| 27 | returned. On a failed write, the switch status is not changed. |
