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