1/*
2 *	Driver for ADC on Atmel AT91 SoC Family
3 *
4 *	Copyright (C) 2010 Claudio Mignanti - c.mignanti@gmail.com
5 *	Based on http://www.at91.com/forum/viewtopic.php/p,9409/#p9409
6 *
7 *	Copyright (C) 2010 Stefano Barbato - stefano@codesink.org
8 *
9 *	2010/05/18 Antonio Galea
10 *		Sysfs device model, different drivers integration
11 *
12 *	WISHLIST:
13 *	- concurrent access control
14 *	- add support for dynamic reconfiguration
15 *	- hardware triggers
16 *
17 *	This program is free software; you can redistribute it and/or modify
18 *	it under the terms of the GNU General Public License as	published by
19 *	the Free Software Foundation.
20 *
21 * ---------------------------------------------------------------------------
22*/
23
24#include <linux/cdev.h>
25#include <linux/clk.h>
26#include <linux/fs.h>
27#include <linux/gpio.h>
28#include <linux/init.h>
29#include <linux/module.h>
30#include <linux/platform_device.h>
31#include <linux/kernel.h>
32#include <linux/smp_lock.h>
33
34#include <asm/io.h>
35
36#include "at91_adc.h"
37
38#define DRV_CLASS	"at91_adc"
39
40#define ADC_REQUEST 		1	//un-used atm
41#define ADC_READ		2
42#define ADC_FREE		3
43
44/* Device functions */
45#define at91_adc_read(reg)				ioread32(at91_adc_base + (reg))
46#define at91_adc_write(reg, val)	iowrite32((val), at91_adc_base + (reg))
47#define AT91_DEFAULT_CONFIG			 AT91_ADC_SHTIM	 | \
48																	AT91_ADC_STARTUP | \
49																	AT91_ADC_PRESCAL | \
50																	AT91_ADC_SLEEP
51
52static void at91_adc_device_release(struct device *dev) {}
53
54struct platform_device at91_adc_device = {
55	.name					= "at91_adc",
56	.id						= -1,
57	.dev.release	 = at91_adc_device_release,
58};
59
60struct clk				*at91_adc_clk;
61void __iomem				*at91_adc_base;
62void __iomem				*at91_pioc_base;
63static struct cdev			*at91_adc_cdev	= NULL;
64static dev_t				at91_adc_devno 	= 0;
65static struct class			*at91_adc_class	= NULL;
66
67static int at91_adc_read_chan(int chan){
68	int val, sr;
69
70	if(chan<0 || chan>3){
71		return -EINVAL;
72	}
73	/* disable pull-up resistor */
74	iowrite32(1 << chan, at91_pioc_base + 0x60);
75
76	at91_adc_write(AT91_ADC_CHER,AT91_ADC_CH(chan));	// Enable Channel
77	at91_adc_write(AT91_ADC_CR,AT91_ADC_START);		//Start the ADC
78
79	for(sr=0; !(sr & AT91_ADC_EOC(chan)); sr=at91_adc_read(AT91_ADC_SR))
80		cpu_relax();
81
82	val=at91_adc_read(AT91_ADC_CHR(chan)) & AT91_ADC_DATA; //Read up to 10 bits
83
84	return val;
85}
86
87/* 	PC0 ->  AD0
88	PC1 -> 	AD1
89	PC2 -> 	AD2
90	PC3 -> 	AD3 */
91static int mux_chan (int chan, int operation) {
92
93	int pin_chan;
94
95	if(chan<0 || chan>3){
96		return -EINVAL;
97	}
98
99	switch (chan) {
100		case 0:
101			pin_chan=AT91_PIN_PC0;
102			break;
103		case 1:
104			pin_chan=AT91_PIN_PC1;
105			break;
106		case 2:
107			pin_chan=AT91_PIN_PC2;
108			break;
109		case 3:
110			pin_chan=AT91_PIN_PC3;
111			break;
112		default:
113			return -EINVAL;
114	}
115
116	if (operation == 1)		//request_chan
117		at91_set_A_periph(pin_chan, 0);				//Mux PIN to GPIO
118	else					//free_chan
119		at91_set_B_periph(pin_chan, 0);				//Mux PIN to GPIO
120
121	return 0;
122}
123
124static int at91_adc_config(int requested_config){
125	int actual_config;
126
127	at91_adc_write(AT91_ADC_CR,AT91_ADC_SWRST);	 //Reset the ADC
128	at91_adc_write(AT91_ADC_MR,requested_config); //Mode setup
129	actual_config = at91_adc_read(AT91_ADC_MR);	 //Read it back
130
131	return (requested_config==actual_config? 0: -EINVAL);
132}
133
134/* Sysfs interface */
135static ssize_t at91_adc_chanX_show(
136	struct device *dev, struct device_attribute *attr, char *buf ){
137
138	ssize_t status = 0;
139	int		 chan = -1;
140	int		 value;
141
142	if(strlen(attr->attr.name)==5 && strncmp(attr->attr.name,"chan",4)==0){
143		chan = attr->attr.name[4]-'0';
144	}
145
146	if(chan<0 || chan>3){
147		return -EIO;
148	}
149
150	value	= at91_adc_read_chan(chan);
151	status = sprintf(buf, "%d\n", value);
152
153	return status;
154}
155
156static DEVICE_ATTR(chan0, 0444, at91_adc_chanX_show, NULL);
157static DEVICE_ATTR(chan1, 0444, at91_adc_chanX_show, NULL);
158static DEVICE_ATTR(chan2, 0444, at91_adc_chanX_show, NULL);
159static DEVICE_ATTR(chan3, 0444, at91_adc_chanX_show, NULL);
160
161static const struct attribute *at91_adc_dev_attrs[] = {
162	&dev_attr_chan0.attr,
163	&dev_attr_chan1.attr,
164	&dev_attr_chan2.attr,
165	&dev_attr_chan3.attr,
166	NULL,
167};
168
169static const struct attribute_group at91_adc_dev_attr_group = {
170	.attrs = (struct attribute **) at91_adc_dev_attrs,
171};
172
173/* IOCTL interface */
174#ifdef HAVE_UNLOCKED_IOCTL
175static long at91_adc_unlocked_ioctl(
176	struct file *file, unsigned int cmd, unsigned long arg){
177#else
178static int at91_adc_ioctl(
179	struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg){
180#endif
181
182	long retval = 0;
183
184#ifdef HAVE_UNLOCKED_IOCTL
185  lock_kernel();
186#endif
187
188	switch (cmd) {
189		case ADC_REQUEST:
190			retval = mux_chan ((int)arg, 1);
191			break;
192
193		case ADC_READ:
194			retval = at91_adc_read_chan((int)arg);
195			break;
196
197		case ADC_FREE:
198			retval = mux_chan ((int)arg, 0);
199			break;
200
201		default:
202			retval = -EINVAL;
203	}
204
205#ifdef HAVE_UNLOCKED_IOCTL
206  unlock_kernel();
207#endif
208
209	return retval;
210}
211
212struct file_operations at91_adc_fops = {
213	.owner = THIS_MODULE,
214#ifdef HAVE_UNLOCKED_IOCTL
215	.unlocked_ioctl = at91_adc_unlocked_ioctl,
216#else
217	.ioctl = at91_adc_ioctl,
218#endif
219};
220
221static void at91_adc_cdev_teardown(void){
222	if(at91_adc_class){
223		device_destroy(at91_adc_class, at91_adc_devno);
224		class_destroy(at91_adc_class);
225	}
226
227	if(at91_adc_devno){
228		unregister_chrdev_region(at91_adc_devno,1);
229		if(at91_adc_cdev){ cdev_del(at91_adc_cdev); }
230	}
231
232	at91_adc_devno = 0;
233	at91_adc_cdev	= NULL;
234	at91_adc_class = NULL;
235	return;
236}
237
238static int at91_adc_cdev_setup(void){
239
240	int status;
241	/* alloc a new device number (major: dynamic, minor: 0) */
242	status = alloc_chrdev_region(&at91_adc_devno,0,1,at91_adc_device.name);
243
244	if(status){
245		goto err;
246	}
247
248	/* create a new char device */
249	at91_adc_cdev = cdev_alloc();
250	if(at91_adc_cdev == NULL){ status=-ENOMEM; goto err; }
251	at91_adc_cdev->owner = THIS_MODULE;
252	at91_adc_cdev->ops	 = &at91_adc_fops;
253	status = cdev_add(at91_adc_cdev,at91_adc_devno,1);
254	if(status){
255		goto err;
256	}
257
258	/* register the class */
259	at91_adc_class = class_create(THIS_MODULE, DRV_CLASS);
260	if(IS_ERR(at91_adc_class)){ status=-EFAULT; goto err; }
261	device_create(at91_adc_class, NULL, at91_adc_devno, NULL, at91_adc_device.name);
262	printk(KERN_INFO "Major: %u; minor: %u\n", \
263		MAJOR(at91_adc_devno), MINOR(at91_adc_devno) \
264	);
265
266	return 0;
267
268err:
269	at91_adc_cdev_teardown();
270	return status;
271}
272
273/* Module init/exit */
274static int __init at91_adc_init(void){
275
276	int status;
277
278	at91_adc_clk = clk_get(NULL,"adc_clk");
279	clk_enable(at91_adc_clk);
280
281	at91_adc_base = ioremap(AT91SAM9260_BASE_ADC,SZ_256);
282	if(!at91_adc_base){
283		status=-ENODEV;
284		goto fail_no_iomem_adc;
285	}
286
287	at91_pioc_base = ioremap(AT91_BASE_SYS + AT91_PIOC,SZ_512);
288	if(!at91_pioc_base){
289		status=-ENODEV;
290		goto fail_no_iomem_pioc;
291	}
292
293	status = platform_device_register(&at91_adc_device);
294	if(status){
295		goto fail_no_dev;
296	}
297
298	status = at91_adc_config(AT91_DEFAULT_CONFIG);
299	if(status){
300		goto fail_no_config;
301	}
302
303	status = sysfs_create_group(
304		&(at91_adc_device.dev.kobj), &at91_adc_dev_attr_group
305	);
306
307	if(status){
308		goto fail_no_sysfs;
309	}
310
311	status = at91_adc_cdev_setup();
312	if(status){
313		goto fail_no_cdev;
314	}
315
316	printk(KERN_INFO "Registered device at91_adc.\n");
317	return 0;
318
319fail_no_cdev:
320fail_no_sysfs:
321	// nothing to undo
322fail_no_config:
323	platform_device_unregister(&at91_adc_device);
324fail_no_dev:
325	iounmap(at91_adc_base);
326fail_no_iomem_pioc:
327	iounmap(at91_pioc_base);
328fail_no_iomem_adc:
329	clk_disable(at91_adc_clk);
330	clk_put(at91_adc_clk);
331	return status;
332}
333
334static void __exit at91_adc_exit(void){
335
336	at91_adc_cdev_teardown();
337	platform_device_unregister(&at91_adc_device);
338	iounmap(at91_adc_base);
339	iounmap(at91_pioc_base);
340
341	clk_disable(at91_adc_clk);
342	clk_put(at91_adc_clk);
343
344	printk(KERN_INFO "Unregistered device at91_adc.\n");
345}
346
347module_init(at91_adc_init);
348module_exit(at91_adc_exit);
349
350MODULE_AUTHOR("Paul Kavan");
351MODULE_AUTHOR("Claudio Mignanti");
352MODULE_AUTHOR("Antonio Galea");
353MODULE_AUTHOR("Stefano Barbato");
354MODULE_DESCRIPTION("ADC Driver for the AT91SAM9G20");
355MODULE_LICENSE("GPL");
356