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/module.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/irqs.h>
  24 #include <mach/map.h>
  25
  26 #include <plat/devs.h>
  27 #include <plat/regs-timer.h>
  28
  29 struct pwm_device {
  30         struct list_head         list;
  31         struct platform_device  *pdev;
  32
  33         struct clk              *clk_div;
  34         struct clk              *clk;
  35         const char              *label;
  36
  37         unsigned int             period_ns;
  38         unsigned int             duty_ns;
  39
  40         unsigned char            tcon_base;
  41         unsigned char            running;
  42         unsigned char            use_count;
  43         unsigned char            pwm_id;
  44 };
  45
  46 #define pwm_dbg(_pwm, msg...) dev_dbg(&(_pwm)->pdev->dev, msg)
  47
  48 static struct clk *clk_scaler[2];
  49
  50 /* Standard setup for a timer block. */
  51
  52 #define TIMER_RESOURCE_SIZE (1)
  53
  54 #define TIMER_RESOURCE(_tmr, _irq)                      \
  55         (struct resource [TIMER_RESOURCE_SIZE]) {       \
  56                 [0] = {                                 \
  57                         .start  = _irq,                 \
  58                         .end    = _irq,                 \
  59                         .flags  = IORESOURCE_IRQ        \
  60                 }                                       \
  61         }
  62
  63 #define DEFINE_S3C_TIMER(_tmr_no, _irq)                 \
  64         .name           = "s3c24xx-pwm",                \
  65         .id             = _tmr_no,                      \
  66         .num_resources  = TIMER_RESOURCE_SIZE,          \
  67         .resource       = TIMER_RESOURCE(_tmr_no, _irq),        \
  68
  69 /* since we already have an static mapping for the timer, we do not
  70  * bother setting any IO resource for the base.
  71  */
  72
  73 struct platform_device s3c_device_timer[] = {
  74         [0] = { DEFINE_S3C_TIMER(0, IRQ_TIMER0) },
  75         [1] = { DEFINE_S3C_TIMER(1, IRQ_TIMER1) },
  76         [2] = { DEFINE_S3C_TIMER(2, IRQ_TIMER2) },
  77         [3] = { DEFINE_S3C_TIMER(3, IRQ_TIMER3) },
  78         [4] = { DEFINE_S3C_TIMER(4, IRQ_TIMER4) },
  79 };
  80
  81 static inline int pwm_is_tdiv(struct pwm_device *pwm)
  82 {
  83         return clk_get_parent(pwm->clk) == pwm->clk_div;
  84 }
  85
  86 static DEFINE_MUTEX(pwm_lock);
  87 static LIST_HEAD(pwm_list);
  88
  89 struct pwm_device *pwm_request(int pwm_id, const char *label)
  90 {
  91         struct pwm_device *pwm;
  92         int found = 0;
  93
  94         mutex_lock(&pwm_lock);
  95
  96         list_for_each_entry(pwm, &pwm_list, list) {
  97                 if (pwm->pwm_id == pwm_id) {
  98                         found = 1;
  99                         break;
 100                 }
 101         }
 102
 103         if (found) {
 104                 if (pwm->use_count == 0) {
 105                         pwm->use_count = 1;
 106                         pwm->label = label;
 107                 } else
 108                         pwm = ERR_PTR(-EBUSY);
 109         } else
 110                 pwm = ERR_PTR(-ENOENT);
 111
 112         mutex_unlock(&pwm_lock);
 113         return pwm;
 114 }
 115
 116 EXPORT_SYMBOL(pwm_request);
 117
 118
 119 void pwm_free(struct pwm_device *pwm)
 120 {
 121         mutex_lock(&pwm_lock);
 122
 123         if (pwm->use_count) {
 124                 pwm->use_count--;
 125                 pwm->label = NULL;
 126         } else
 127                 printk(KERN_ERR "PWM%d device already freed\n", pwm->pwm_id);
 128
 129         mutex_unlock(&pwm_lock);
 130 }
 131
 132 EXPORT_SYMBOL(pwm_free);
 133
 134 #define pwm_tcon_start(pwm) (1 << (pwm->tcon_base + 0))
 135 #define pwm_tcon_invert(pwm) (1 << (pwm->tcon_base + 2))
 136 #define pwm_tcon_autoreload(pwm) (1 << (pwm->tcon_base + 3))
 137 #define pwm_tcon_manulupdate(pwm) (1 << (pwm->tcon_base + 1))
 138
 139 int pwm_enable(struct pwm_device *pwm)
 140 {
 141         unsigned long flags;
 142         unsigned long tcon;
 143
 144         local_irq_save(flags);
 145
 146         tcon = __raw_readl(S3C2410_TCON);
 147         tcon |= pwm_tcon_start(pwm);
 148         __raw_writel(tcon, S3C2410_TCON);
 149
 150         local_irq_restore(flags);
 151
 152         pwm->running = 1;
 153         return 0;
 154 }
 155
 156 EXPORT_SYMBOL(pwm_enable);
 157
 158 void pwm_disable(struct pwm_device *pwm)
 159 {
 160         unsigned long flags;
 161         unsigned long tcon;
 162
 163         local_irq_save(flags);
 164
 165         tcon = __raw_readl(S3C2410_TCON);
 166         tcon &= ~pwm_tcon_start(pwm);
 167         __raw_writel(tcon, S3C2410_TCON);
 168
 169         local_irq_restore(flags);
 170
 171         pwm->running = 0;
 172 }
 173
 174 EXPORT_SYMBOL(pwm_disable);
 175
 176 static unsigned long pwm_calc_tin(struct pwm_device *pwm, unsigned long freq)
 177 {
 178         unsigned long tin_parent_rate;
 179         unsigned int div;
 180
 181         tin_parent_rate = clk_get_rate(clk_get_parent(pwm->clk_div));
 182         pwm_dbg(pwm, "tin parent at %lu\n", tin_parent_rate);
 183
 184         for (div = 2; div <= 16; div *= 2) {
 185                 if ((tin_parent_rate / (div << 16)) < freq)
 186                         return tin_parent_rate / div;
 187         }
 188
 189         return tin_parent_rate / 16;
 190 }
 191
 192 #define NS_IN_HZ (1000000000UL)
 193
 194 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
 195 {
 196         unsigned long tin_rate;
 197         unsigned long tin_ns;
 198         unsigned long period;
 199         unsigned long flags;
 200         unsigned long tcon;
 201         unsigned long tcnt;
 202         long tcmp;
 203
 204         /* We currently avoid using 64bit arithmetic by using the
 205          * fact that anything faster than 1Hz is easily representable
 206          * by 32bits. */
 207
 208         if (period_ns > NS_IN_HZ || duty_ns > NS_IN_HZ)
 209                 return -ERANGE;
 210
 211         if (duty_ns > period_ns)
 212                 return -EINVAL;
 213
 214         if (period_ns == pwm->period_ns &&
 215             duty_ns == pwm->duty_ns)
 216                 return 0;
 217
 218         /* The TCMP and TCNT can be read without a lock, they're not
 219          * shared between the timers. */
 220
 221         tcmp = __raw_readl(S3C2410_TCMPB(pwm->pwm_id));
 222         tcnt = __raw_readl(S3C2410_TCNTB(pwm->pwm_id));
 223
 224         period = NS_IN_HZ / period_ns;
 225
 226         pwm_dbg(pwm, "duty_ns=%d, period_ns=%d (%lu)\n",
 227                 duty_ns, period_ns, period);
 228
 229         /* Check to see if we are changing the clock rate of the PWM */
 230
 231         if (pwm->period_ns != period_ns) {
 232                 if (pwm_is_tdiv(pwm)) {
 233                         tin_rate = pwm_calc_tin(pwm, period);
 234                         clk_set_rate(pwm->clk_div, tin_rate);
 235                 } else
 236                         tin_rate = clk_get_rate(pwm->clk);
 237
 238                 pwm->period_ns = period_ns;
 239
 240                 pwm_dbg(pwm, "tin_rate=%lu\n", tin_rate);
 241
 242                 tin_ns = NS_IN_HZ / tin_rate;
 243                 tcnt = period_ns / tin_ns;
 244         } else
 245                 tin_ns = NS_IN_HZ / clk_get_rate(pwm->clk);
 246
 247         /* Note, counters count down */
 248
 249         tcmp = duty_ns / tin_ns;
 250         tcmp = tcnt - tcmp;
 251         /* the pwm hw only checks the compare register after a decrement,
 252            so the pin never toggles if tcmp = tcnt */
 253         if (tcmp == tcnt)
 254                 tcmp--;
 255
 256         pwm_dbg(pwm, "tin_ns=%lu, tcmp=%ld/%lu\n", tin_ns, tcmp, tcnt);
 257
 258         if (tcmp < 0)
 259                 tcmp = 0;
 260
 261         /* Update the PWM register block. */
 262
 263         local_irq_save(flags);
 264
 265         __raw_writel(tcmp, S3C2410_TCMPB(pwm->pwm_id));
 266         __raw_writel(tcnt, S3C2410_TCNTB(pwm->pwm_id));
 267
 268         tcon = __raw_readl(S3C2410_TCON);
 269         tcon |= pwm_tcon_manulupdate(pwm);
 270         tcon |= pwm_tcon_autoreload(pwm);
 271         __raw_writel(tcon, S3C2410_TCON);
 272
 273         tcon &= ~pwm_tcon_manulupdate(pwm);
 274         __raw_writel(tcon, S3C2410_TCON);
 275
 276         local_irq_restore(flags);
 277
 278         return 0;
 279 }
 280
 281 EXPORT_SYMBOL(pwm_config);
 282
 283 static int pwm_register(struct pwm_device *pwm)
 284 {
 285         pwm->duty_ns = -1;
 286         pwm->period_ns = -1;
 287
 288         mutex_lock(&pwm_lock);
 289         list_add_tail(&pwm->list, &pwm_list);
 290         mutex_unlock(&pwm_lock);
 291
 292         return 0;
 293 }
 294
 295 static int s3c_pwm_probe(struct platform_device *pdev)
 296 {
 297         struct device *dev = &pdev->dev;
 298         struct pwm_device *pwm;
 299         unsigned long flags;
 300         unsigned long tcon;
 301         unsigned int id = pdev->id;
 302         int ret;
 303
 304         if (id == 4) {
 305                 dev_err(dev, "TIMER4 is currently not supported\n");
 306                 return -ENXIO;
 307         }
 308
 309         pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
 310         if (pwm == NULL) {
 311                 dev_err(dev, "failed to allocate pwm_device\n");
 312                 return -ENOMEM;
 313         }
 314
 315         pwm->pdev = pdev;
 316         pwm->pwm_id = id;
 317
 318         /* calculate base of control bits in TCON */
 319         pwm->tcon_base = id == 0 ? 0 : (id * 4) + 4;
 320
 321         pwm->clk = clk_get(dev, "pwm-tin");
 322         if (IS_ERR(pwm->clk)) {
 323                 dev_err(dev, "failed to get pwm tin clk\n");
 324                 ret = PTR_ERR(pwm->clk);
 325                 goto err_alloc;
 326         }
 327
 328         pwm->clk_div = clk_get(dev, "pwm-tdiv");
 329         if (IS_ERR(pwm->clk_div)) {
 330                 dev_err(dev, "failed to get pwm tdiv clk\n");
 331                 ret = PTR_ERR(pwm->clk_div);
 332                 goto err_clk_tin;
 333         }
 334
 335         local_irq_save(flags);
 336
 337         tcon = __raw_readl(S3C2410_TCON);
 338         tcon |= pwm_tcon_invert(pwm);
 339         __raw_writel(tcon, S3C2410_TCON);
 340
 341         local_irq_restore(flags);
 342
 343
 344         ret = pwm_register(pwm);
 345         if (ret) {
 346                 dev_err(dev, "failed to register pwm\n");
 347                 goto err_clk_tdiv;
 348         }
 349
 350         pwm_dbg(pwm, "config bits %02x\n",
 351                 (__raw_readl(S3C2410_TCON) >> pwm->tcon_base) & 0x0f);
 352
 353         dev_info(dev, "tin at %lu, tdiv at %lu, tin=%sclk, base %d\n",
 354                  clk_get_rate(pwm->clk),
 355                  clk_get_rate(pwm->clk_div),
 356                  pwm_is_tdiv(pwm) ? "div" : "ext", pwm->tcon_base);
 357
 358         platform_set_drvdata(pdev, pwm);
 359         return 0;
 360
 361  err_clk_tdiv:
 362         clk_put(pwm->clk_div);
 363
 364  err_clk_tin:
 365         clk_put(pwm->clk);
 366
 367  err_alloc:
 368         kfree(pwm);
 369         return ret;
 370 }
 371
 372 static int __devexit s3c_pwm_remove(struct platform_device *pdev)
 373 {
 374         struct pwm_device *pwm = platform_get_drvdata(pdev);
 375
 376         clk_put(pwm->clk_div);
 377         clk_put(pwm->clk);
 378         kfree(pwm);
 379
 380         return 0;
 381 }
 382
 383 #ifdef CONFIG_PM
 384 static int s3c_pwm_suspend(struct platform_device *pdev, pm_message_t state)
 385 {
 386         struct pwm_device *pwm = platform_get_drvdata(pdev);
 387
 388         /* No one preserve these values during suspend so reset them
 389          * Otherwise driver leaves PWM unconfigured if same values
 390          * passed to pwm_config
 391          */
 392         pwm->period_ns = 0;
 393         pwm->duty_ns = 0;
 394
 395         return 0;
 396 }
 397
 398 static int s3c_pwm_resume(struct platform_device *pdev)
 399 {
 400         struct pwm_device *pwm = platform_get_drvdata(pdev);
 401         unsigned long tcon;
 402
 403         /* Restore invertion */
 404         tcon = __raw_readl(S3C2410_TCON);
 405         tcon |= pwm_tcon_invert(pwm);
 406         __raw_writel(tcon, S3C2410_TCON);
 407
 408         return 0;
 409 }
 410
 411 #else
 412 #define s3c_pwm_suspend NULL
 413 #define s3c_pwm_resume NULL
 414 #endif
 415
 416 static struct platform_driver s3c_pwm_driver = {
 417         .driver         = {
 418                 .name   = "s3c24xx-pwm",
 419                 .owner  = THIS_MODULE,
 420         },
 421         .probe          = s3c_pwm_probe,
 422         .remove         = __devexit_p(s3c_pwm_remove),
 423         .suspend        = s3c_pwm_suspend,
 424         .resume         = s3c_pwm_resume,
 425 };
 426
 427 static int __init pwm_init(void)
 428 {
 429         int ret;
 430
 431         clk_scaler[0] = clk_get(NULL, "pwm-scaler0");
 432         clk_scaler[1] = clk_get(NULL, "pwm-scaler1");
 433
 434         if (IS_ERR(clk_scaler[0]) || IS_ERR(clk_scaler[1])) {
 435                 printk(KERN_ERR "%s: failed to get scaler clocks\n", __func__);
 436                 return -EINVAL;
 437         }
 438
 439         ret = platform_driver_register(&s3c_pwm_driver);
 440         if (ret)
 441                 printk(KERN_ERR "%s: failed to add pwm driver\n", __func__);
 442
 443         return ret;
 444 }
 445
 446 arch_initcall(pwm_init);