--- /dev/null
+/*
+ * 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");
--- /dev/null
+/*
+ * include/asm-arm/arch-at91/at91_adc.h
+ *
+ * Copyright (C) SAN People
+ *
+ * Analog-to-Digital Converter (ADC) registers.
+ * Based on AT91SAM9260 datasheet revision D.
+ *
+ * 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; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef AT91_ADC_H
+#define AT91_ADC_H
+
+#define AT91_ADC_CR 0x00 /* Control Register */
+#define AT91_ADC_SWRST (1 << 0) /* Software Reset */
+#define AT91_ADC_START (1 << 1) /* Start Conversion */
+
+#define AT91_ADC_MR 0x04 /* Mode Register */
+#define AT91_ADC_TRGEN (1 << 0) /* Trigger Enable */
+#define AT91_ADC_TRGSEL (7 << 1) /* Trigger Selection */
+#define AT91_ADC_TRGSEL_TC0 (0 << 1)
+#define AT91_ADC_TRGSEL_TC1 (1 << 1)
+#define AT91_ADC_TRGSEL_TC2 (2 << 1)
+#define AT91_ADC_TRGSEL_EXTERNAL (6 << 1)
+#define AT91_ADC_LOWRES (1 << 4) /* Low Resolution */
+#define AT91_ADC_SLEEP (1 << 5) /* Sleep Mode */
+#define AT91_ADC_PRESCAL (0x3f << 8) /* Prescalar Rate Selection */
+#define AT91_ADC_PRESCAL_(x) ((x) << 8)
+#define AT91_ADC_STARTUP (0x1f << 16) /* Startup Up Time */
+#define AT91_ADC_STARTUP_(x) ((x) << 16)
+#define AT91_ADC_SHTIM (0xf << 24) /* Sample & Hold Time */
+#define AT91_ADC_SHTIM_(x) ((x) << 24)
+
+#define AT91_ADC_CHER 0x10 /* Channel Enable Register */
+#define AT91_ADC_CHDR 0x14 /* Channel Disable Register */
+#define AT91_ADC_CHSR 0x18 /* Channel Status Register */
+#define AT91_ADC_CH(n) (1 << (n)) /* Channel Number */
+
+#define AT91_ADC_SR 0x1C /* Status Register */
+#define AT91_ADC_EOC(n) (1 << (n)) /* End of Conversion on Channel N */
+#define AT91_ADC_OVRE(n) (1 << ((n) + 8))/* Overrun Error on Channel N */
+#define AT91_ADC_DRDY (1 << 16) /* Data Ready */
+#define AT91_ADC_GOVRE (1 << 17) /* General Overrun Error */
+#define AT91_ADC_ENDRX (1 << 18) /* End of RX Buffer */
+#define AT91_ADC_RXFUFF (1 << 19) /* RX Buffer Full */
+
+#define AT91_ADC_LCDR 0x20 /* Last Converted Data Register */
+#define AT91_ADC_LDATA (0x3ff)
+
+#define AT91_ADC_IER 0x24 /* Interrupt Enable Register */
+#define AT91_ADC_IDR 0x28 /* Interrupt Disable Register */
+#define AT91_ADC_IMR 0x2C /* Interrupt Mask Register */
+
+#define AT91_ADC_CHR(n) (0x30 + ((n) * 4)) /* Channel Data Register N */
+#define AT91_ADC_DATA (0x3ff)
+
+#endif
+
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