arch/arm/plat-samsung/pwm.c

   1 /* arch/arm/plat-s3c/pwm.c
   2  *
   3  * Copyright (c) 2007 Ben Dooks
   4  * Copyright (c) 2008 Simtec Electronics
   5  *      Ben Dooks <ben@simtec.co.uk>, <ben-linux@fluff.org>
   6  *
   7  * S3C series PWM device core
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License.
  12 */
  13
  14 #include <linux/export.h>
  15 #include <linux/kernel.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/slab.h>
  18 #include <linux/err.h>
  19 #include <linux/clk.h>
  20 #include <linux/io.h>
  21 #include <linux/pwm.h>
  22
  23 #include <mach/map.h>
  24
  25 #include <plat/regs-timer.h>
  26
  27 struct pwm_device {
  28         struct list_head         list;
  29         struct platform_device  *pdev;
  30
  31         struct clk              *clk_div;
  32         struct clk              *clk;
  33         const char              *label;
  34
  35         unsigned int             period_ns;
  36         unsigned int             duty_ns;
  37
  38         unsigned char            tcon_base;
  39         unsigned char            use_count;
  40         unsigned char            pwm_id;
  41 };
  42
  43 #define pwm_dbg(_pwm, msg...) dev_dbg(&(_pwm)->pdev->dev, msg)
  44
  45 static struct clk *clk_scaler[2];
  46
  47 static inline int pwm_is_tdiv(struct pwm_device *pwm)
  48 {
  49         return clk_get_parent(pwm->clk) == pwm->clk_div;
  50 }
  51
  52 static DEFINE_MUTEX(pwm_lock);
  53 static LIST_HEAD(pwm_list);
  54
  55 struct pwm_device *pwm_request(int pwm_id, const char *label)
  56 {
  57         struct pwm_device *pwm;
  58         int found = 0;
  59
  60         mutex_lock(&pwm_lock);
  61
  62         list_for_each_entry(pwm, &pwm_list, list) {
  63                 if (pwm->pwm_id == pwm_id) {
  64                         found = 1;
  65                         break;
  66                 }
  67         }
  68
  69         if (found) {
  70                 if (pwm->use_count == 0) {
  71                         pwm->use_count = 1;
  72                         pwm->label = label;
  73                 } else
  74                         pwm = ERR_PTR(-EBUSY);
  75         } else
  76                 pwm = ERR_PTR(-ENOENT);
  77
  78         mutex_unlock(&pwm_lock);
  79         return pwm;
  80 }
  81
  82 EXPORT_SYMBOL(pwm_request);
  83
  84
  85 void pwm_free(struct pwm_device *pwm)
  86 {
  87         mutex_lock(&pwm_lock);
  88
  89         if (pwm->use_count) {
  90                 pwm->use_count--;
  91                 pwm->label = NULL;
  92         } else
  93                 printk(KERN_ERR "PWM%d device already freed\n", pwm->pwm_id);
  94
  95         mutex_unlock(&pwm_lock);
  96 }
  97
  98 EXPORT_SYMBOL(pwm_free);
  99
 100 #define pwm_tcon_start(pwm) (1 << (pwm->tcon_base + 0))
 101 #define pwm_tcon_invert(pwm) (1 << (pwm->tcon_base + 2))
 102 #define pwm_tcon_autoreload(pwm) (1 << (pwm->tcon_base + 3))
 103 #define pwm_tcon_manulupdate(pwm) (1 << (pwm->tcon_base + 1))
 104
 105 int pwm_enable(struct pwm_device *pwm)
 106 {
 107         unsigned long flags;
 108         unsigned long tcon;
 109
 110         local_irq_save(flags);
 111
 112         tcon = __raw_readl(S3C2410_TCON);
 113         tcon |= pwm_tcon_start(pwm);
 114         __raw_writel(tcon, S3C2410_TCON);
 115
 116         local_irq_restore(flags);
 117
 118         return 0;
 119 }
 120
 121 EXPORT_SYMBOL(pwm_enable);
 122
 123 void pwm_disable(struct pwm_device *pwm)
 124 {
 125         unsigned long flags;
 126         unsigned long tcon;
 127
 128         local_irq_save(flags);
 129
 130         tcon = __raw_readl(S3C2410_TCON);
 131         tcon &= ~pwm_tcon_start(pwm);
 132         __raw_writel(tcon, S3C2410_TCON);
 133
 134         local_irq_restore(flags);
 135 }
 136
 137 EXPORT_SYMBOL(pwm_disable);
 138
 139 static unsigned long pwm_calc_tin(struct pwm_device *pwm, unsigned long freq)
 140 {
 141         unsigned long tin_parent_rate;
 142         unsigned int div;
 143
 144         tin_parent_rate = clk_get_rate(clk_get_parent(pwm->clk_div));
 145         pwm_dbg(pwm, "tin parent at %lu\n", tin_parent_rate);
 146
 147         for (div = 2; div <= 16; div *= 2) {
 148                 if ((tin_parent_rate / (div << 16)) < freq)
 149                         return tin_parent_rate / div;
 150         }
 151
 152         return tin_parent_rate / 16;
 153 }
 154
 155 #define NS_IN_HZ (1000000000UL)
 156
 157 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
 158 {
 159         unsigned long tin_rate;
 160         unsigned long tin_ns;
 161         unsigned long period;
 162         unsigned long flags;
 163         unsigned long tcon;
 164         unsigned long tcnt;
 165         long tcmp;
 166
 167         /* We currently avoid using 64bit arithmetic by using the
 168          * fact that anything faster than 1Hz is easily representable
 169          * by 32bits. */
 170
 171         if (period_ns > NS_IN_HZ || duty_ns > NS_IN_HZ)
 172                 return -ERANGE;
 173
 174         if (duty_ns > period_ns)
 175                 return -EINVAL;
 176
 177         if (period_ns == pwm->period_ns &&
 178             duty_ns == pwm->duty_ns)
 179                 return 0;
 180
 181         /* The TCMP and TCNT can be read without a lock, they're not
 182          * shared between the timers. */
 183
 184         tcmp = __raw_readl(S3C2410_TCMPB(pwm->pwm_id));
 185         tcnt = __raw_readl(S3C2410_TCNTB(pwm->pwm_id));
 186
 187         period = NS_IN_HZ / period_ns;
 188
 189         pwm_dbg(pwm, "duty_ns=%d, period_ns=%d (%lu)\n",
 190                 duty_ns, period_ns, period);
 191
 192         /* Check to see if we are changing the clock rate of the PWM */
 193
 194         if (pwm->period_ns != period_ns) {
 195                 if (pwm_is_tdiv(pwm)) {
 196                         tin_rate = pwm_calc_tin(pwm, period);
 197                         clk_set_rate(pwm->clk_div, tin_rate);
 198                 } else
 199                         tin_rate = clk_get_rate(pwm->clk);
 200
 201                 pwm->period_ns = period_ns;
 202
 203                 pwm_dbg(pwm, "tin_rate=%lu\n", tin_rate);
 204
 205                 tin_ns = NS_IN_HZ / tin_rate;
 206                 tcnt = period_ns / tin_ns;
 207         } else
 208                 tin_ns = NS_IN_HZ / clk_get_rate(pwm->clk);
 209
 210         /* Note, counters count down */
 211
 212         tcmp = duty_ns / tin_ns;
 213         tcmp = tcnt - tcmp;
 214         /* the pwm hw only checks the compare register after a decrement,
 215            so the pin never toggles if tcmp = tcnt */
 216         if (tcmp == tcnt)
 217                 tcmp--;
 218
 219         pwm_dbg(pwm, "tin_ns=%lu, tcmp=%ld/%lu\n", tin_ns, tcmp, tcnt);
 220
 221         if (tcmp < 0)
 222                 tcmp = 0;
 223
 224         /* Update the PWM register block. */
 225
 226         local_irq_save(flags);
 227
 228         __raw_writel(tcmp, S3C2410_TCMPB(pwm->pwm_id));
 229         __raw_writel(tcnt, S3C2410_TCNTB(pwm->pwm_id));
 230
 231         tcon = __raw_readl(S3C2410_TCON);
 232         tcon |= pwm_tcon_manulupdate(pwm);
 233         tcon |= pwm_tcon_autoreload(pwm);
 234         __raw_writel(tcon, S3C2410_TCON);
 235
 236         tcon &= ~pwm_tcon_manulupdate(pwm);
 237         __raw_writel(tcon, S3C2410_TCON);
 238
 239         local_irq_restore(flags);
 240
 241         return 0;
 242 }
 243
 244 EXPORT_SYMBOL(pwm_config);
 245
 246 static int pwm_register(struct pwm_device *pwm)
 247 {
 248         pwm->duty_ns = -1;
 249         pwm->period_ns = -1;
 250
 251         mutex_lock(&pwm_lock);
 252         list_add_tail(&pwm->list, &pwm_list);
 253         mutex_unlock(&pwm_lock);
 254
 255         return 0;
 256 }
 257
 258 static int s3c_pwm_probe(struct platform_device *pdev)
 259 {
 260         struct device *dev = &pdev->dev;
 261         struct pwm_device *pwm;
 262         unsigned long flags;
 263         unsigned long tcon;
 264         unsigned int id = pdev->id;
 265         int ret;
 266
 267         if (id == 4) {
 268                 dev_err(dev, "TIMER4 is currently not supported\n");
 269                 return -ENXIO;
 270         }
 271
 272         pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
 273         if (pwm == NULL) {
 274                 dev_err(dev, "failed to allocate pwm_device\n");
 275                 return -ENOMEM;
 276         }
 277
 278         pwm->pdev = pdev;
 279         pwm->pwm_id = id;
 280
 281         /* calculate base of control bits in TCON */
 282         pwm->tcon_base = id == 0 ? 0 : (id * 4) + 4;
 283
 284         pwm->clk = clk_get(dev, "pwm-tin");
 285         if (IS_ERR(pwm->clk)) {
 286                 dev_err(dev, "failed to get pwm tin clk\n");
 287                 ret = PTR_ERR(pwm->clk);
 288                 goto err_alloc;
 289         }
 290
 291         pwm->clk_div = clk_get(dev, "pwm-tdiv");
 292         if (IS_ERR(pwm->clk_div)) {
 293                 dev_err(dev, "failed to get pwm tdiv clk\n");
 294                 ret = PTR_ERR(pwm->clk_div);
 295                 goto err_clk_tin;
 296         }
 297
 298         clk_enable(pwm->clk);
 299         clk_enable(pwm->clk_div);
 300
 301         local_irq_save(flags);
 302
 303         tcon = __raw_readl(S3C2410_TCON);
 304         tcon |= pwm_tcon_invert(pwm);
 305         __raw_writel(tcon, S3C2410_TCON);
 306
 307         local_irq_restore(flags);
 308
 309
 310         ret = pwm_register(pwm);
 311         if (ret) {
 312                 dev_err(dev, "failed to register pwm\n");
 313                 goto err_clk_tdiv;
 314         }
 315
 316         pwm_dbg(pwm, "config bits %02x\n",
 317                 (__raw_readl(S3C2410_TCON) >> pwm->tcon_base) & 0x0f);
 318
 319         dev_info(dev, "tin at %lu, tdiv at %lu, tin=%sclk, base %d\n",
 320                  clk_get_rate(pwm->clk),
 321                  clk_get_rate(pwm->clk_div),
 322                  pwm_is_tdiv(pwm) ? "div" : "ext", pwm->tcon_base);
 323
 324         platform_set_drvdata(pdev, pwm);
 325         return 0;
 326
 327  err_clk_tdiv:
 328         clk_disable(pwm->clk_div);
 329         clk_disable(pwm->clk);
 330         clk_put(pwm->clk_div);
 331
 332  err_clk_tin:
 333         clk_put(pwm->clk);
 334
 335  err_alloc:
 336         kfree(pwm);
 337         return ret;
 338 }
 339
 340 static int __devexit s3c_pwm_remove(struct platform_device *pdev)
 341 {
 342         struct pwm_device *pwm = platform_get_drvdata(pdev);
 343
 344         clk_disable(pwm->clk_div);
 345         clk_disable(pwm->clk);
 346         clk_put(pwm->clk_div);
 347         clk_put(pwm->clk);
 348         kfree(pwm);
 349
 350         return 0;
 351 }
 352
 353 #ifdef CONFIG_PM
 354 static int s3c_pwm_suspend(struct platform_device *pdev, pm_message_t state)
 355 {
 356         struct pwm_device *pwm = platform_get_drvdata(pdev);
 357
 358         /* No one preserve these values during suspend so reset them
 359          * Otherwise driver leaves PWM unconfigured if same values
 360          * passed to pwm_config
 361          */
 362         pwm->period_ns = 0;
 363         pwm->duty_ns = 0;
 364
 365         return 0;
 366 }
 367
 368 static int s3c_pwm_resume(struct platform_device *pdev)
 369 {
 370         struct pwm_device *pwm = platform_get_drvdata(pdev);
 371         unsigned long tcon;
 372
 373         /* Restore invertion */
 374         tcon = __raw_readl(S3C2410_TCON);
 375         tcon |= pwm_tcon_invert(pwm);
 376         __raw_writel(tcon, S3C2410_TCON);
 377
 378         return 0;
 379 }
 380
 381 #else
 382 #define s3c_pwm_suspend NULL
 383 #define s3c_pwm_resume NULL
 384 #endif
 385
 386 static struct platform_driver s3c_pwm_driver = {
 387         .driver         = {
 388                 .name   = "s3c24xx-pwm",
 389                 .owner  = THIS_MODULE,
 390         },
 391         .probe          = s3c_pwm_probe,
 392         .remove         = __devexit_p(s3c_pwm_remove),
 393         .suspend        = s3c_pwm_suspend,
 394         .resume         = s3c_pwm_resume,
 395 };
 396
 397 static int __init pwm_init(void)
 398 {
 399         int ret;
 400
 401         clk_scaler[0] = clk_get(NULL, "pwm-scaler0");
 402         clk_scaler[1] = clk_get(NULL, "pwm-scaler1");
 403
 404         if (IS_ERR(clk_scaler[0]) || IS_ERR(clk_scaler[1])) {
 405                 printk(KERN_ERR "%s: failed to get scaler clocks\n", __func__);
 406                 return -EINVAL;
 407         }
 408
 409         ret = platform_driver_register(&s3c_pwm_driver);
 410         if (ret)
 411                 printk(KERN_ERR "%s: failed to add pwm driver\n", __func__);
 412
 413         return ret;
 414 }
 415
 416 arch_initcall(pwm_init);