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openwrt/target/linux/at91/files/drivers/misc/at91-adc.c

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/*
* Driver for ADC on Atmel AT91 SoC Family
*
* Copyright (C) 2010 Claudio Mignanti - c.mignanti@gmail.com
* Based on http://www.at91.com/forum/viewtopic.php/p,9409/#p9409
*
* Copyright (C) 2010 Stefano Barbato - stefano@codesink.org
*
* 2010/05/18 Antonio Galea
* Sysfs device model, different drivers integration
*
* WISHLIST:
* - concurrent access control
* - add support for dynamic reconfiguration
* - hardware triggers
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation.
*
* ---------------------------------------------------------------------------
*/
#include <linux/cdev.h>
#include <linux/clk.h>
#include <linux/fs.h>
#include <linux/gpio.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/kernel.h>
#include <linux/smp_lock.h>
#include <asm/io.h>
#include "at91_adc.h"
#define DRV_CLASS "at91_adc"
#define ADC_REQUEST 1 //un-used atm
#define ADC_READ 2
#define ADC_FREE 3
/* Device functions */
#define at91_adc_read(reg) ioread32(at91_adc_base + (reg))
#define at91_adc_write(reg, val) iowrite32((val), at91_adc_base + (reg))
#define AT91_DEFAULT_CONFIG AT91_ADC_SHTIM | \
AT91_ADC_STARTUP | \
AT91_ADC_PRESCAL | \
AT91_ADC_SLEEP
static void at91_adc_device_release(struct device *dev) {}
struct platform_device at91_adc_device = {
.name = "at91_adc",
.id = -1,
.dev.release = at91_adc_device_release,
};
struct clk *at91_adc_clk;
void __iomem *at91_adc_base;
void __iomem *at91_pioc_base;
static struct cdev *at91_adc_cdev = NULL;
static dev_t at91_adc_devno = 0;
static struct class *at91_adc_class = NULL;
static int at91_adc_read_chan(int chan){
int val, sr;
if(chan<0 || chan>3){
return -EINVAL;
}
/* disable pull-up resistor */
iowrite32(1 << chan, at91_pioc_base + 0x60);
at91_adc_write(AT91_ADC_CHER,AT91_ADC_CH(chan)); // Enable Channel
at91_adc_write(AT91_ADC_CR,AT91_ADC_START); //Start the ADC
for(sr=0; !(sr & AT91_ADC_EOC(chan)); sr=at91_adc_read(AT91_ADC_SR))
cpu_relax();
val=at91_adc_read(AT91_ADC_CHR(chan)) & AT91_ADC_DATA; //Read up to 10 bits
return val;
}
/* PC0 -> AD0
PC1 -> AD1
PC2 -> AD2
PC3 -> AD3 */
static int mux_chan (int chan, int operation) {
int pin_chan;
if(chan<0 || chan>3){
return -EINVAL;
}
switch (chan) {
case 0:
pin_chan=AT91_PIN_PC0;
break;
case 1:
pin_chan=AT91_PIN_PC1;
break;
case 2:
pin_chan=AT91_PIN_PC2;
break;
case 3:
pin_chan=AT91_PIN_PC3;
break;
default:
return -EINVAL;
}
if (operation == 1) //request_chan
at91_set_A_periph(pin_chan, 0); //Mux PIN to GPIO
else //free_chan
at91_set_B_periph(pin_chan, 0); //Mux PIN to GPIO
return 0;
}
static int at91_adc_config(int requested_config){
int actual_config;
at91_adc_write(AT91_ADC_CR,AT91_ADC_SWRST); //Reset the ADC
at91_adc_write(AT91_ADC_MR,requested_config); //Mode setup
actual_config = at91_adc_read(AT91_ADC_MR); //Read it back
return (requested_config==actual_config? 0: -EINVAL);
}
/* Sysfs interface */
static ssize_t at91_adc_chanX_show(
struct device *dev, struct device_attribute *attr, char *buf ){
ssize_t status = 0;
int chan = -1;
int value;
if(strlen(attr->attr.name)==5 && strncmp(attr->attr.name,"chan",4)==0){
chan = attr->attr.name[4]-'0';
}
if(chan<0 || chan>3){
return -EIO;
}
value = at91_adc_read_chan(chan);
status = sprintf(buf, "%d\n", value);
return status;
}
static DEVICE_ATTR(chan0, 0444, at91_adc_chanX_show, NULL);
static DEVICE_ATTR(chan1, 0444, at91_adc_chanX_show, NULL);
static DEVICE_ATTR(chan2, 0444, at91_adc_chanX_show, NULL);
static DEVICE_ATTR(chan3, 0444, at91_adc_chanX_show, NULL);
static const struct attribute *at91_adc_dev_attrs[] = {
&dev_attr_chan0.attr,
&dev_attr_chan1.attr,
&dev_attr_chan2.attr,
&dev_attr_chan3.attr,
NULL,
};
static const struct attribute_group at91_adc_dev_attr_group = {
.attrs = (struct attribute **) at91_adc_dev_attrs,
};
/* IOCTL interface */
#ifdef HAVE_UNLOCKED_IOCTL
static long at91_adc_unlocked_ioctl(
struct file *file, unsigned int cmd, unsigned long arg){
#else
static int at91_adc_ioctl(
struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg){
#endif
long retval = 0;
#ifdef HAVE_UNLOCKED_IOCTL
lock_kernel();
#endif
switch (cmd) {
case ADC_REQUEST:
retval = mux_chan ((int)arg, 1);
break;
case ADC_READ:
retval = at91_adc_read_chan((int)arg);
break;
case ADC_FREE:
retval = mux_chan ((int)arg, 0);
break;
default:
retval = -EINVAL;
}
#ifdef HAVE_UNLOCKED_IOCTL
unlock_kernel();
#endif
return retval;
}
struct file_operations at91_adc_fops = {
.owner = THIS_MODULE,
#ifdef HAVE_UNLOCKED_IOCTL
.unlocked_ioctl = at91_adc_unlocked_ioctl,
#else
.ioctl = at91_adc_ioctl,
#endif
};
static void at91_adc_cdev_teardown(void){
if(at91_adc_class){
device_destroy(at91_adc_class, at91_adc_devno);
class_destroy(at91_adc_class);
}
if(at91_adc_devno){
unregister_chrdev_region(at91_adc_devno,1);
if(at91_adc_cdev){ cdev_del(at91_adc_cdev); }
}
at91_adc_devno = 0;
at91_adc_cdev = NULL;
at91_adc_class = NULL;
return;
}
static int at91_adc_cdev_setup(void){
int status;
/* alloc a new device number (major: dynamic, minor: 0) */
status = alloc_chrdev_region(&at91_adc_devno,0,1,at91_adc_device.name);
if(status){
goto err;
}
/* create a new char device */
at91_adc_cdev = cdev_alloc();
if(at91_adc_cdev == NULL){ status=-ENOMEM; goto err; }
at91_adc_cdev->owner = THIS_MODULE;
at91_adc_cdev->ops = &at91_adc_fops;
status = cdev_add(at91_adc_cdev,at91_adc_devno,1);
if(status){
goto err;
}
/* register the class */
at91_adc_class = class_create(THIS_MODULE, DRV_CLASS);
if(IS_ERR(at91_adc_class)){ status=-EFAULT; goto err; }
device_create(at91_adc_class, NULL, at91_adc_devno, NULL, at91_adc_device.name);
printk(KERN_INFO "Major: %u; minor: %u\n", \
MAJOR(at91_adc_devno), MINOR(at91_adc_devno) \
);
return 0;
err:
at91_adc_cdev_teardown();
return status;
}
/* Module init/exit */
static int __init at91_adc_init(void){
int status;
at91_adc_clk = clk_get(NULL,"adc_clk");
clk_enable(at91_adc_clk);
at91_adc_base = ioremap(AT91SAM9260_BASE_ADC,SZ_256);
if(!at91_adc_base){
status=-ENODEV;
goto fail_no_iomem_adc;
}
at91_pioc_base = ioremap(AT91_BASE_SYS + AT91_PIOC,SZ_512);
if(!at91_pioc_base){
status=-ENODEV;
goto fail_no_iomem_pioc;
}
status = platform_device_register(&at91_adc_device);
if(status){
goto fail_no_dev;
}
status = at91_adc_config(AT91_DEFAULT_CONFIG);
if(status){
goto fail_no_config;
}
status = sysfs_create_group(
&(at91_adc_device.dev.kobj), &at91_adc_dev_attr_group
);
if(status){
goto fail_no_sysfs;
}
status = at91_adc_cdev_setup();
if(status){
goto fail_no_cdev;
}
printk(KERN_INFO "Registered device at91_adc.\n");
return 0;
fail_no_cdev:
fail_no_sysfs:
// nothing to undo
fail_no_config:
platform_device_unregister(&at91_adc_device);
fail_no_dev:
iounmap(at91_adc_base);
fail_no_iomem_pioc:
iounmap(at91_pioc_base);
fail_no_iomem_adc:
clk_disable(at91_adc_clk);
clk_put(at91_adc_clk);
return status;
}
static void __exit at91_adc_exit(void){
at91_adc_cdev_teardown();
platform_device_unregister(&at91_adc_device);
iounmap(at91_adc_base);
iounmap(at91_pioc_base);
clk_disable(at91_adc_clk);
clk_put(at91_adc_clk);
printk(KERN_INFO "Unregistered device at91_adc.\n");
}
module_init(at91_adc_init);
module_exit(at91_adc_exit);
MODULE_AUTHOR("Paul Kavan");
MODULE_AUTHOR("Claudio Mignanti");
MODULE_AUTHOR("Antonio Galea");
MODULE_AUTHOR("Stefano Barbato");
MODULE_DESCRIPTION("ADC Driver for the AT91SAM9G20");
MODULE_LICENSE("GPL");
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