Tom,
Looks like Linux actually has a driver for this touchscreen.
linux-2.6-xlnx/drivers/input/touchscreen/ads7846.c
Assuming that you've built a kernel with the Xilinx SPI driver and the driver for this touch screen, you'll need to figure out how to properly edit the device tree (the .dts file) to specify that this touchscreen is present. This driver is not device-tree aware, so you'll need to make use of the kernel's workaround for the device (99% of SPI drivers haven't yet been modified to use the device tree directly yet).
Find the name of the driver in ads7846.c:
static struct spi_driver ads7846_driver = {
.driver = {
.name = "ads7846",
.bus = &spi_bus_type,
.owner = THIS_MODULE,
},
.probe = ads7846_probe,
.remove = __devexit_p(ads7846_remove),
.suspend = ads7846_suspend,
.resume = ads7846_resume,
};
Add this name and a device tree allias for it to the modalias table in drivers/of/base.c
Something like:
static struct of_modalias_table of_modalias_table[] = {
{ "fsl,mcu-mpc8349emitx", "mcu-mpc8349emitx" },
{ "mmc-spi-slot", "mmc_spi" },
{ "my-pretty-name", "ads7846" },
};
Add the device to your SPI bus controller in your .dts file and rebuild:
SPI_CONTROLLER: xps-spi@83400000 {
compatible = "xlnx,xps-spi-2.01.b", "xlnx,xps-spi-2.00.a";
interrupt-parent = <&Interrupt_Cntlr>;
interrupts = < 4 2 >;
reg = < 0x83400000 0x10000 >;
xlnx,family = "spartan6";
xlnx,fifo-exist = <0x1>;
xlnx,num-ss-bits = <0x1>;
xlnx,num-transfer-bits = <0x8>;
xlnx,sck-ratio = <0x20>;
my_touchscreen@0 {
compatible = "my-pretty-name", "ads7846";
reg = <0>;
spi-max-frequency = <10000000>;
};
} ;
And see if this driver recognizes your device at bootup.
In short, you've got some figuring out to do :-)
-Brian
