diff options
Diffstat (limited to 'Documentation/w1/masters/omap-hdq')
-rw-r--r-- | Documentation/w1/masters/omap-hdq | 46 |
1 files changed, 46 insertions, 0 deletions
diff --git a/Documentation/w1/masters/omap-hdq b/Documentation/w1/masters/omap-hdq new file mode 100644 index 000000000000..ca722e09b6a1 --- /dev/null +++ b/Documentation/w1/masters/omap-hdq | |||
@@ -0,0 +1,46 @@ | |||
1 | Kernel driver for omap HDQ/1-wire module. | ||
2 | ======================================== | ||
3 | |||
4 | Supported chips: | ||
5 | ================ | ||
6 | HDQ/1-wire controller on the TI OMAP 2430/3430 platforms. | ||
7 | |||
8 | A useful link about HDQ basics: | ||
9 | =============================== | ||
10 | http://focus.ti.com/lit/an/slua408/slua408.pdf | ||
11 | |||
12 | Description: | ||
13 | ============ | ||
14 | The HDQ/1-Wire module of TI OMAP2430/3430 platforms implement the hardware | ||
15 | protocol of the master functions of the Benchmark HDQ and the Dallas | ||
16 | Semiconductor 1-Wire protocols. These protocols use a single wire for | ||
17 | communication between the master (HDQ/1-Wire controller) and the slave | ||
18 | (HDQ/1-Wire external compliant device). | ||
19 | |||
20 | A typical application of the HDQ/1-Wire module is the communication with battery | ||
21 | monitor (gas gauge) integrated circuits. | ||
22 | |||
23 | The controller supports operation in both HDQ and 1-wire mode. The essential | ||
24 | difference between the HDQ and 1-wire mode is how the slave device responds to | ||
25 | initialization pulse.In HDQ mode, the firmware does not require the host to | ||
26 | create an initialization pulse to the slave.However, the slave can be reset by | ||
27 | using an initialization pulse (also referred to as a break pulse).The slave | ||
28 | does not respond with a presence pulse as it does in the 1-Wire protocol. | ||
29 | |||
30 | Remarks: | ||
31 | ======== | ||
32 | The driver (drivers/w1/masters/omap_hdq.c) supports the HDQ mode of the | ||
33 | controller. In this mode, as we can not read the ID which obeys the W1 | ||
34 | spec(family:id:crc), a module parameter can be passed to the driver which will | ||
35 | be used to calculate the CRC and pass back an appropriate slave ID to the W1 | ||
36 | core. | ||
37 | |||
38 | By default the master driver and the BQ slave i/f | ||
39 | driver(drivers/w1/slaves/w1_bq27000.c) sets the ID to 1. | ||
40 | Please note to load both the modules with a different ID if required, but note | ||
41 | that the ID used should be same for both master and slave driver loading. | ||
42 | |||
43 | e.g: | ||
44 | insmod omap_hdq.ko W1_ID=2 | ||
45 | inamod w1_bq27000.ko F_ID=2 | ||
46 | |||