I have trouble to get second chip select working on the Beaglebone Black.
I used the .dts given in /lib/firmware with my distribution (Angstrom, kernel 3.8.13) :
/*
* Copyright (C) 2013 CircuitCo
*
* Virtual cape for SPI1 on connector pins P9.29 P9.31 P9.30 P9.28
*
* 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.
*/
/dts-v1/;
/plugin/;
/ {
compatible = "ti,beaglebone", "ti,beaglebone-black";
/* identification */
part-number = "BB-SPI1-01";
version = "00A0";
/* state the resources this cape uses */
exclusive-use =
/* the pin header uses */
"P9.31", /* spi1_sclk */
"P9.29", /* spi1_d0 */
"P9.30", /* spi1_d1 */
"P9.28", /* spi1_cs0 */
"P9.42", /* spi1_cs1 */
/* the hardware ip uses */
"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 0x13 /* mcasp0_aclkx.spi1_sclk, OUTPUT_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 */
0x164 0x12 /* eCAP0_in_PWM0_out.spi1_cs1 OUTPUT_PULLUP | MODE2 */
>;
};
};
};
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>;
cs-gpios = <&gpio4 17 0>, <&gpio1 7 0>;
spi1_0{
#address-cells = <1>;
#size-cells = <0>;
compatible = "spidev";
reg = <0>;
spi-max-frequency = <16000000>;
};
spi1_1{
#address-cells = <1>;
#size-cells = <0>;
compatible = "spidev";
reg = <1>;
spi-max-frequency = <16000000>;
};
};
};
};
I compiled it with dtc and activate it with uEnv.txt :
capemgr.enable_partno=BB-SPI1-01
(Both HDMI and HDMIN capes are disabled)
I have the twos SPI device shown in /dev/ :
/dev/spidev2.0 /dev/spidev2.1
and the pins are used by the spi interface as shown :
root@beaglebone:~# cat $PINS | grep spi1
pin 89 (44e10964): 481a0000.spi (GPIO UNCLAIMED) function pinmux_bb_spi1_pins group pinmux_bb_spi1_pins
pin 100 (44e10990): 481a0000.spi (GPIO UNCLAIMED) function pinmux_bb_spi1_pins group pinmux_bb_spi1_pins
pin 101 (44e10994): 481a0000.spi (GPIO UNCLAIMED) function pinmux_bb_spi1_pins group pinmux_bb_spi1_pins
pin 102 (44e10998): 481a0000.spi (GPIO UNCLAIMED) function pinmux_bb_spi1_pins group pinmux_bb_spi1_pins
pin 103 (44e1099c): 481a0000.spi (GPIO UNCLAIMED) function pinmux_bb_spi1_pins group pinmux_bb_spi1_pins
And the mode is good :
pin 89 (44e10964) 00000012 pinctrl-single
pin 100 (44e10990) 00000013 pinctrl-single
pin 101 (44e10994) 00000033 pinctrl-single
pin 102 (44e10998) 00000013 pinctrl-single
pin 103 (44e1099c) 00000013 pinctrl-single
I successfully use a programm in C which use the first spidev (spidev2.0) with the first chip select, but the there are nothing on pin 42 when I use spidev2.1 (MOSI,MISO and CLK are working though).
Any ideas ?
Thanks in advance
Well I found out the answer myself :
The pin 42 is special since it's connected to two I/O. So in order to use one of the I/O, you have to put the other one as input.
source : Beaglebone black system reference manual http://www.digikey.com/web%20export/supplier%20content/ti_296/mkt/boards/BBB_SRM.pdf?redirected=1 page 71.
But now i have an other issue really strange... I posted it here : Trouble with SPIDEV, device tree and .dtbo name with Beaglebone Black