Still struggling with Xilinx GPIO...
John Bonesio
john.bonesio at xilinx.com
Wed May 28 02:42:20 EST 2008
Hi Guillaume,
Try using channel 1. It may be set up where the first channel is 1 and
not 0.
- John
On Mon, 2008-05-26 at 17:43 +0200, Guillaume Dargaud wrote:
> I still haven't managed to figure out how to use the Xilinx GPIO from
> usermode.
>
> The program gpio_test found at
> http://www.itee.uq.edu.au/~listarch/microblaze-uclinux/archive/2004/05/msg00004.html
> and slightly modified as this:
>
> #include <stdio.h>
> #include <fcntl.h>
> #include <errno.h>
> #include <string.h>
>
> #include <linux/types.h>
> #include <sys/ioctl.h>
>
> #include <xgpio_ioctl.h>
>
> #define GPIO_DEV "/dev/xgpio"
>
> void usage(int argc, char *argv[])
> {
> fprintf(stderr,"usage: %s hexval\n\n", argv[0]);
> fprintf(stderr,"\n");
> fprintf(stderr,"Puts the input hexval onto the LEDs, and\n");
> fprintf(stderr,"displays the current value on the DIP switches\n");
> fprintf(stderr,"\n");
> fprintf(stderr,"try gpio_test FC\n\n");
>
> }
>
> void dump_dipsw(int val)
> {
> int i;
> val = (val & 0x000000FF);
>
> printf("DIP SW: ");
> for(i=0;i<8;i++)
> {
> printf("%i",val & 0x01);
> val >>= 1;
> }
> printf("\n");
> }
>
> /* Turn 4 LSB of X into 8 bit LED segment code */
> unsigned char nyb_hex2led(int x)
> {
> unsigned char led_tab[] = {
> 0xFC, 0x60, 0xDA, 0xF2,
> 0x66, 0xB6, 0xBE, 0xE0,
> 0xFE, 0xF6, 0xEE, 0x3E,
> 0x9C, 0x7A, 0x9E, 0x8E};
>
> return led_tab[x & 0xF];
> }
>
> /* Turn 8 LSB of x into 2 times 8 bit LED segment codes */
> unsigned short hex2led(int x)
> {
> return (nyb_hex2led(x & 0xF) << 8) | (nyb_hex2led((x >> 4) & 0xF));
> }
>
> int main(int argc, char *argv[])
> {
> /* Open the device */
> int fd = open(GPIO_DEV, O_RDWR);
>
> struct xgpio_ioctl_data gpio_ioctl;
> // struct ibm_gpio_ioctl_data gpio_ioctl;
> // int result;
> // int command;
>
> if(fd==-1) {
> fprintf(stderr,"Unable to open %s\n", GPIO_DEV);
> return -1;
> }
>
> /*
> if(argc!=2)
> {
> usage();
> exit(1);
> }
> */
> gpio_ioctl.chan=0;
>
> /* Set the tristates */
> gpio_ioctl.mask=0x000000FF;
> ioctl(fd, XGPIO_TRISTATE,(void *)&gpio_ioctl);
>
> /* Get output data from command line if provided */
>
> if(argc==2)
> sscanf(argv[1],"%x",&(gpio_ioctl.data));
> else
> gpio_ioctl.data=time(NULL);
>
> /* Convert binary (16 LSB) into LED segment codes and shift into
> position on gpio */
> gpio_ioctl.data=hex2led(gpio_ioctl.data & 0xFF)<<8;
>
> ioctl(fd, XGPIO_OUT,(void *)&gpio_ioctl);
>
> /* Read some data */
> ioctl(fd, XGPIO_IN,(void *)&gpio_ioctl);
>
> dump_dipsw(gpio_ioctl.data);
>
> return 0;
> }
>
>
> ...crashes in flames when run:
>
> # gpio_test FC
> [ 1366.864955] Oops: kernel access of bad area, sig: 11 [#5]
> [ 1366.867560] NIP: c0108d50 LR: c00e68c4 CTR: 00000000
> [ 1366.867560] REGS: c752fde0 TRAP: 0300 Tainted: G D (2.6.25-rc9)
> [ 1366.867560] MSR: 00029030 <EE,ME,IR,DR> CR: 93000033 XER: e000007f
> [ 1366.867560] DEAR: c8fffffc, ESR: 00000000
> [ 1366.867560] TASK = c7c37030[202] 'gpio_test' THREAD: c752e000
> [ 1366.867560] GPR00: 00000000 c752fe90 c7c37030 c8fffffc 00000056 0000000c
> c752feb0 00000000
> [ 1366.867560] GPR08: 00000000 11111111 ffffffe7 c7c5866c 00000000 10018dec
> ffff8432 ffdf1d0f
> [ 1366.867560] GPR16: ffffffff ffffffff ffffffff ffffffff ffffffff 00000000
> 100af244 10000858
> [ 1366.867560] GPR24: 10000c00 00000002 10000478 800c5a03 c7c58000 c7c5866c
> 800c5a03 c0200000
> [ 1366.867560] NIP [c0108d50] XIo_In32+0x4/0xc
> [ 1366.867560] LR [c00e68c4] XGpio_GetDataDirection+0x84/0xac
> [ 1366.867560] Call Trace:
> [ 1366.867560] [c752fe90] [c00e66a8] xgpio_getinst+0x48/0xb0 (unreliable)
> [ 1366.867560] [c752fea0] [c00e6a8c] xgpio_ioctl+0x1a0/0x1fc
> [ 1366.867560] [c752fed0] [c006740c] vfs_ioctl+0x6c/0x84
> [ 1366.867560] [c752fee0] [c006778c] do_vfs_ioctl+0x368/0x39c
> [ 1366.867560] [c752ff10] [c0067800] sys_ioctl+0x40/0x70
> [ 1366.867560] [c752ff40] [c0002770] ret_from_syscall+0x0/0x3c
> [ 1366.867560] Instruction dump:
> [ 1366.867560] 7c634b78 7c031b78 4e800020 7c0006ac 88630000 5463063e
> 4e800020 7c0006ac
> [ 1366.867560] a0630000 5463043e 4e800020 7c0006ac <80630000> 4e800020
> 7c0006ac 7c601e2c
> Segmentation fault
>
>
> # dmesg | grep gpio
> [ 0.120666] Registering device xilinx_gpio:0
> [ 0.121672] Registering device xilinx_gpio:1
> [ 0.122682] Registering device xilinx_gpio:2
> [ 0.292352] xgpio0 #0 at 0x81400000 mapped to 0xC9000000 device: 10,185
> using IRQ#7
> [ 0.293805] xgpio1 #1 at 0x81420000 mapped to 0xC9020000 device: 10,186
> using IRQ#6
> [ 0.295062] xgpio2 #2 at 0x81440000 mapped to 0xC9040000 device: 10,187
> using IRQ#5
> [ 1366.867560] TASK = c7c37030[202] 'gpio_test' THREAD: c752e000
> [ 1366.867560] [c752fe90] [c00e66a8] xgpio_getinst+0x48/0xb0 (unreliable)
> [ 1366.867560] [c752fea0] [c00e6a8c] xgpio_ioctl+0x1a0/0x1fc
>
>
>
> Another program using a different strategy also fails:
>
> #include <fcntl.h>
> #include <stdio.h>
>
> int main (int argc, char *argv[]) {
> if (argc==2 || argc==3) {
>
> int fd = open(argv[1], O_RDWR | O_NDELAY );
> if (fd < 0) {
> fprintf(stderr, "GPIO OPEN FAIL\n");
> return -1;
> }
>
> unsigned long buff = 0;
> if (argc==2) {
> if (read(fd, &buff, 4) != 4)
> fprintf(stderr, "GPIO READ ERROR\n");
> else printf( "%x\n", buff);
> } else {
> buff=atoi(argv[2]);
> if (write(fd, &buff, 4) != 4)
> fprintf(stderr, "GPIO WRITE ERROR value %x\n", buff);
> else printf( "Written %x successfully\n", buff);
> }
>
> close(fd);
> } else {
> fprintf(stderr, "Usage: %s device [value] to read or write data to gpio
> device\n", argv[0]);
> return 1;
> }
>
> return 0;
> }
>
>
> # GpioReadWrite /dev/xgpio
> GPIO READ ERROR
> # GpioReadWrite /dev/xgpio 7
> GPIO WRITE ERROR value 0
>
> I wanted to avoid writing a kernel module, but apparently I've ran out of
> options...
________________________________________________________________________
John Bonesio
Commercial Linux Solutions
john.bonesio at xilinx.com
(408) 879-5569
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