Hello,
I am trying to bring up an AD7192 under the new IIO standard in linux. I am using the 3.8 version of the kernel on a BeagleBone black. I am having trouble understand the devices tree structure for industrial IO.
In particular I define a new spi device that looks like
/*
* Copyright (C) 2013 Elemental Semiconductor
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program has been developed to support the DAQ system being developed
* by Elemental Semiconductor/
*/
/dts-v1/;
/plugin/;
/ {
compatible = "ti,beaglebone-black", "ti,am335x-bone";
/* identification */
part-number = "es_daq";
version = "0010";
/* We need to use the SPI bus for the AD7192 */
exclusive-use =
/* the pin header uses */
"P9.28", /* spi1_cs0 */
"P9.29", /* spi1_d0 */
"P9.30", /* spi1_d1 */
"P9.31", /* spi1_sclk */
"p9.27", /* interrupt data ready */
/* the hardware ip uses */
"gpio3_19",
"spi1";
fragment@0 {
target = <&am33xx_pinmux>;
__overlay__ {
/* default state has all gpios released and mode set to uart1 */
bb_spi1_pins: pinmux_bb_spi1_pins {
pinctrl-single,pins = <
0x190 0x33 /* mcasp0_aclkx.spi1_sclk, INPUT_PULLUP | MODE3 */
0x194 0x33 /* mcasp0_fsx.spi1_d0, INPUT_PULLUP | MODE3 */
0x198 0x13 /* mcasp0_axr0.spi1_d1, OUTPUT_PULLUP | MODE3 */
0x19c 0x13 /* mcasp0_ahclkr.spi1_cs0, OUTPUT_PULLUP | MODE3 */
>;
};
bb_adc0_pins: pinmux_bb_gpio3_pins {
pinctrl-single,pins = <
0x18c 0x2f /* DRDY interrupt INPUT | PULLDIS | MODE7 */
>;
};
};
};
fragment@1 {
target = <&spi1>; /* spi1 is numbered correctly */
__overlay__ {
status = "okay";
pinctrl-names = "default";
pinctrl-0 = <&bb_spi1_pins>;
#address-cells = <1>;
#size-cells = <0>;
// We try to add in the adc
adc@0{
#address-cells = <1>;
#size-cells = <0>;
compatible = "ad,ad7192";
reg = <0>;
// The ad7192 can handle 5MHz, but our isolators are only good
// to 1MHz. So we back of to 500KHz
spi-max-frequency = <500000>;
// we want to invert the normal operation for the AD7192
spi-cpol;
spi-cpha;
// Make sure the interrupt pin is mentioned here
pinctrl-names = "default";
pinctrl-0 = <&bb_adc0_pins>;
interrupt-parent = <&gpio3>;
interrupts = <19 0x0>;
irq-gpio = <&gpio3 19 0>;
// I think we need to identify this device as an iio device
#io-channel-cells = <1>;
};
};
};
};
This file works at some level, because I see the ad7192 kernel module being loaded, and the api bus show an ad7182 registered. The problem is I don't see the iiodevices showing up in the /dev directory. I thought adding the #io-channel-cells = <1>; was sufficient, but apparently it is not.
Does anyone have any advice on how I should define the DTS file to make the system understand that I want to use the AD7192 as an IIO device?
Oliver
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