Messages in this thread | | | Subject | Re: [PATCH/RFC] simple SPI controller on PXA2xx SSP port, refresh | From | Stephen Street <> | Date | Thu, 27 Oct 2005 09:41:00 -0700 |
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On Thu, 2005-10-27 at 19:33 +0800, Mike Lee wrote: > Dear Stepen > I am now writing another controller driver by david's framework. > But leak of debuging layer, could your loopback driver serve for this > purpose and how could i use it? >
The file pxa2xx_loopback.c should be controller independent, but it does require that the hardware (in my case the PXA255 NSSP) support a loopback mode (i.e. tx connected to rx).
To create a loopback device for driver you should include:
static struct pxa2xx_spi_chip loopback_chip_info = { .mode = SPI_MODE_3, .tx_threshold = 12, .rx_threshold = 4, .dma_burst_size = 8, .bits_per_word = 8, .timeout_microsecs = 64, .enable_loopback = 1, };
static struct spi_board_info streetracer_spi_board_info[] __initdata = { { .modalias = "loopback", .max_speed_hz = 3686400, .bus_num = 2, .chip_select = 3, .controller_data = &loopback_chip_info, }, };
in your board init code and install the module per your configuration. Anything written to /dev/slp23 will be echoed back to /dev/slp23 via the "SPI controller".
Hope this helps!
-Stephen
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