Hi, the ADC kernel driver only supports reading on channel 0, so i've made a kernel module with the source of the ADC driver and changed the channel to 1. It works if i load the module and do "cat /dev/battery", but then the touchscreen isn't working, even if i remove the module. I have to reboot to get it working again. Heres my source Code for the module. I hope anyone can Help me! http://uc.pastebin.com/VFr959W1
If i'm not mistaken then the touch screen uses the other ADC lines.
Try keeping the name of the mutex (ADC_LOCK), because it is what the touchscreen module (see s3c2410_ts.c in drivers/input/touchscreen) uses too, so that the ADC is only accessed by one of them at a time.
If i keep the name ADC_LOCK i have to unexport it at the bottom of the file. But even if i do this, this has no effect on the touchscreen-behauviour. It still won't work together with the ADC.
This is a silly answer, but if all you want to do is change the channel just change line 120 in mini2440_adc.c I'm just starting to look at ways to write a driver that allows one to select the channel. If I find something I'll post it.
I've just tried the kernel compiled with the attached file besides the
mini2440_adc.c (just a line in the drivers/char/Makefile needs to be
changed) and now I can read both from channel 0 (/dev/adc, no changes from
the original) and from channel 1 (/dev/adc1). I also attach the little
program to test it (see the note in it if you don't do the test from the
host PC). Hope this helps.
Well, I can't attach more than one file, so here is the test program:
//------------------------------------------------------------------------------
// PROJECT:
// mini2440 ADC driver test
//
// FILE:
// readadc.c
//
// PURPOSE:
// Show ADC readings from the channel selected by the user
//
// FUNCTIONS PROVIDED:
// -
//
// FUNCTIONS CALLED:
// -
//
// HISTORY:
// 2010.05.17 Created
//
//------------------------------------------------------------------------------
#include <stdio.h>
//------------------------------------------------------------------------------
// main
//
// DESCRIPTION:
// Selects ADC channel according to the arguments with which it was
called,
// takes ADC reading, and shows it on stdout
//
// ARGUMENTS:
// argc
// Number of arguments of the user call (the executable file name
// counts as argument 0)
// argv
// Array of pointers to the strings representing the arguments
//
// RETURNED VALUE:
// int
// 0 if everything OK
// -1 otherwise
//
// NOTES:
// 1. There has to be a function called main to link with arm-linux-gcc,
and
// it has to return an int so that there are no warnings
// 2. If this function is called using the touchscreen, the reading will
be -1
// unless the pen is quickly lifted from the touchscreen after touching
<ret>
//
//------------------------------------------------------------------------------
int main(int argc, char * argv[]) {
char buffer[30];
int value,
fd,
len;
if(argc != 2) {
printf("Usage: %s <adc_ch_no>\n", argv[0]);
return -1;
}
switch(atoi(argv[1])) {
case 0:
fd = open("/dev/adc", 0);
break;
case 1:
fd = open("/dev/adc1", 0);
break;
default:
break;
}
if(fd < 0) {
printf("Unable to open ADC device\n");
return -1;
}
len = read(fd, buffer, sizeof buffer - 1);
if(len > 0) {
buffer[len] = '\0';
value = -1;
sscanf(buffer, "%d", &value);
printf("Channel %d: %d counts\n", atoi(argv[1]), value);
close(fd);
return 0;
} else {
printf("Unable to read from ADC device\n");
close(fd);
return -1;
}
}
//------------------------------------------------------------------------------
// END OF FILE
//------------------------------------------------------------------------------
Hello! I'm trying to use all ADC channels. I've found that thread and have some questions. Should I create three different files for all channels (mini2440_adc1,2,3)? Or maybe there is simpler way to do it? And what about that Makefile - should I just add one more line "obj-$(CONFIG_MINI2440_ADC) += mini2440_adc[1..3].o"? Or just change one (but then i think i will have only one channel, right?)? thanks in advance best regards Tomasz
Hi elucches, I could not attach the file in Makefile the file mini2440_adc1 in order to compile both files... I try do add in the makefile follow: obj-$(CONFIG_MINI2440_ADC1) += mini2440_adc1.o but doesn't work!! what changes in the makefile I do to attach both files??? thanks in advance Joaci
Why after i added in adc_ioctl this line into mini2440_adc.c, i can use
other channel but the touchscreen become not function?
static long adc_ioctl(struct file *file,unsigned int cmd,unsigned long arg)
{
//printk("arg=%d\ncmd=%d\n",arg,cmd);
//printk("arg=%d\ncmd=%d\n",(int)arg,(int)cmd);
switch((int)cmd)
{
case 0:
adcdev.channel = (int)arg;
//printk("adcdev.channel=%d\ncmd=%d",adcdev.channel,cmd);
break;
case 1:
adcdev.prescale = (int)arg;
//printk("adcdev.prescale=%d\n",adcdev.prescale);
break;
default:
return -EINVAL;
//printk("default");
break;
}
return 0;
}