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| 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 | |||
