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

   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
  52 static void at91_adc_device_release(struct device *dev) {}
  53
  54 struct platform_device at91_adc_device = {
  55         .name                                   = "at91_adc",
  56         .id                                             = -1,
  57         .dev.release     = at91_adc_device_release,
  58 };
  59
  60 struct clk                              *at91_adc_clk;
  61 void __iomem                            *at91_adc_base;
  62 void __iomem                            *at91_pioc_base;
  63 static struct cdev                      *at91_adc_cdev  = NULL;
  64 static dev_t                            at91_adc_devno  = 0;
  65 static struct class                     *at91_adc_class = NULL;
  66
  67 static 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 */
  91 static 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
 124 static 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 */
 135 static 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
 156 static DEVICE_ATTR(chan0, 0444, at91_adc_chanX_show, NULL);
 157 static DEVICE_ATTR(chan1, 0444, at91_adc_chanX_show, NULL);
 158 static DEVICE_ATTR(chan2, 0444, at91_adc_chanX_show, NULL);
 159 static DEVICE_ATTR(chan3, 0444, at91_adc_chanX_show, NULL);
 160
 161 static 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
 169 static 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
 175 static long at91_adc_unlocked_ioctl(
 176         struct file *file, unsigned int cmd, unsigned long arg){
 177 #else
 178 static 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
 212 struct 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
 221 static 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
 238 static 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
 268 err:
 269         at91_adc_cdev_teardown();
 270         return status;
 271 }
 272
 273 /* Module init/exit */
 274 static 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
 319 fail_no_cdev:
 320 fail_no_sysfs:
 321         // nothing to undo
 322 fail_no_config:
 323         platform_device_unregister(&at91_adc_device);
 324 fail_no_dev:
 325         iounmap(at91_adc_base);
 326 fail_no_iomem_pioc:
 327         iounmap(at91_pioc_base);
 328 fail_no_iomem_adc:
 329         clk_disable(at91_adc_clk);
 330         clk_put(at91_adc_clk);
 331         return status;
 332 }
 333
 334 static 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
 347 module_init(at91_adc_init);
 348 module_exit(at91_adc_exit);
 349
 350 MODULE_AUTHOR("Paul Kavan");
 351 MODULE_AUTHOR("Claudio Mignanti");
 352 MODULE_AUTHOR("Antonio Galea");
 353 MODULE_AUTHOR("Stefano Barbato");
 354 MODULE_DESCRIPTION("ADC Driver for the AT91SAM9G20");
 355 MODULE_LICENSE("GPL");