Import an experimental ADC driver

SVN-Revision: 24814

2 files changed, 417 insertions, 0 deletions

diff --git a/target/linux/at91/files/drivers/misc/at91-adc.c b/target/linux/at91/files/drivers/misc/at91-adc.c
new file mode 100644
index 0000000..90ea818
--- /dev/null
+++ b/target/linux/at91/files/drivers/misc/at91-adc.c
@@ -0,0 +1,355 @@
+/*
+ *	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");
diff --git a/target/linux/at91/files/drivers/misc/at91_adc.h b/target/linux/at91/files/drivers/misc/at91_adc.h
new file mode 100644
index 0000000..2d6f01d
--- /dev/null
+++ b/target/linux/at91/files/drivers/misc/at91_adc.h
@@ -0,0 +1,62 @@
+/*
+ * 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
+