arch/arm/plat-s3c24xx/pwm.c

   1 /* arch/arm/plat-s3c24xx/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  * S3C24XX 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/err.h>
  18 #include <linux/clk.h>
  19 #include <linux/io.h>
  20 #include <linux/pwm.h>
  21
  22 #include <mach/irqs.h>
  23
  24 #include <plat/devs.h>
  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            running;
  40         unsigned char            use_count;
  41         unsigned char            pwm_id;
  42 };
  43
  44 #define pwm_dbg(_pwm, msg...) dev_dbg(&(_pwm)->pdev->dev, msg)
  45
  46 static struct clk *clk_scaler[2];
  47
  48 /* Standard setup for a timer block. */
  49
  50 #define TIMER_RESOURCE_SIZE (1)
  51
  52 #define TIMER_RESOURCE(_tmr, _irq)                      \
  53         (struct resource [TIMER_RESOURCE_SIZE]) {       \
  54                 [0] = {                                 \
  55                         .start  = _irq,                 \
  56                         .end    = _irq,                 \
  57                         .flags  = IORESOURCE_IRQ        \
  58                 }                                       \
  59         }
  60
  61 #define DEFINE_S3C_TIMER(_tmr_no, _irq)                 \
  62         .name           = "s3c24xx-pwm",                \
  63         .id             = _tmr_no,                      \
  64         .num_resources  = TIMER_RESOURCE_SIZE,          \
  65         .resource       = TIMER_RESOURCE(_tmr_no, _irq),        \
  66
  67 /* since we already have an static mapping for the timer, we do not
  68  * bother setting any IO resource for the base.
  69  */
  70
  71 struct platform_device s3c_device_timer[] = {
  72         [0] = { DEFINE_S3C_TIMER(0, IRQ_TIMER0) },
  73         [1] = { DEFINE_S3C_TIMER(1, IRQ_TIMER1) },
  74         [2] = { DEFINE_S3C_TIMER(2, IRQ_TIMER2) },
  75         [3] = { DEFINE_S3C_TIMER(3, IRQ_TIMER3) },
  76         [4] = { DEFINE_S3C_TIMER(4, IRQ_TIMER4) },
  77 };
  78
  79 static inline int pwm_is_tdiv(struct pwm_device *pwm)
  80 {
  81         return clk_get_parent(pwm->clk) == pwm->clk_div;
  82 }
  83
  84 static DEFINE_MUTEX(pwm_lock);
  85 static LIST_HEAD(pwm_list);
  86
  87 struct pwm_device *pwm_request(int pwm_id, const char *label)
  88 {
  89         struct pwm_device *pwm;
  90         int found = 0;
  91
  92         mutex_lock(&pwm_lock);
  93
  94         list_for_each_entry(pwm, &pwm_list, list) {
  95                 if (pwm->pwm_id == pwm_id) {
  96                         found = 1;
  97                         break;
  98                 }
  99         }
 100
 101         if (found) {
 102                 if (pwm->use_count == 0) {
 103                         pwm->use_count = 1;
 104                         pwm->label = label;
 105                 } else
 106                         pwm = ERR_PTR(-EBUSY);
 107         } else
 108                 pwm = ERR_PTR(-ENOENT);
 109
 110         mutex_unlock(&pwm_lock);
 111         return pwm;
 112 }
 113
 114 EXPORT_SYMBOL(pwm_request);
 115
 116
 117 void pwm_free(struct pwm_device *pwm)
 118 {
 119         mutex_lock(&pwm_lock);
 120
 121         if (pwm->use_count) {
 122                 pwm->use_count--;
 123                 pwm->label = NULL;
 124         } else
 125                 printk(KERN_ERR "PWM%d device already freed\n", pwm->pwm_id);
 126
 127         mutex_unlock(&pwm_lock);
 128 }
 129
 130 EXPORT_SYMBOL(pwm_free);
 131
 132 #define pwm_tcon_start(pwm) (1 << (pwm->tcon_base + 0))
 133 #define pwm_tcon_invert(pwm) (1 << (pwm->tcon_base + 2))
 134 #define pwm_tcon_autoreload(pwm) (1 << (pwm->tcon_base + 3))
 135 #define pwm_tcon_manulupdate(pwm) (1 << (pwm->tcon_base + 1))
 136
 137 int pwm_enable(struct pwm_device *pwm)
 138 {
 139         unsigned long flags;
 140         unsigned long tcon;
 141
 142         local_irq_save(flags);
 143
 144         tcon = __raw_readl(S3C2410_TCON);
 145         tcon |= pwm_tcon_start(pwm);
 146         __raw_writel(tcon, S3C2410_TCON);
 147
 148         local_irq_restore(flags);
 149
 150         pwm->running = 1;
 151         return 0;
 152 }
 153
 154 EXPORT_SYMBOL(pwm_enable);
 155
 156 void pwm_disable(struct pwm_device *pwm)
 157 {
 158         unsigned long flags;
 159         unsigned long tcon;
 160
 161         local_irq_save(flags);
 162
 163         tcon = __raw_readl(S3C2410_TCON);
 164         tcon &= ~pwm_tcon_start(pwm);
 165         __raw_writel(tcon, S3C2410_TCON);
 166
 167         local_irq_restore(flags);
 168
 169         pwm->running = 0;
 170 }
 171
 172 EXPORT_SYMBOL(pwm_disable);
 173
 174 static unsigned long pwm_calc_tin(struct pwm_device *pwm, unsigned long freq)
 175 {
 176         unsigned long tin_parent_rate;
 177         unsigned int div;
 178
 179         tin_parent_rate = clk_get_rate(clk_get_parent(pwm->clk_div));
 180         pwm_dbg(pwm, "tin parent at %lu\n", tin_parent_rate);
 181
 182         for (div = 2; div <= 16; div *= 2) {
 183                 if ((tin_parent_rate / (div << 16)) < freq)
 184                         return tin_parent_rate / div;
 185         }
 186
 187         return tin_parent_rate / 16;
 188 }
 189
 190 #define NS_IN_HZ (1000000000UL)
 191
 192 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
 193 {
 194         unsigned long tin_rate;
 195         unsigned long tin_ns;
 196         unsigned long period;
 197         unsigned long flags;
 198         unsigned long tcon;
 199         unsigned long tcnt;
 200         long tcmp;
 201
 202         /* We currently avoid using 64bit arithmetic by using the
 203          * fact that anything faster than 1Hz is easily representable
 204          * by 32bits. */
 205
 206         if (period_ns > NS_IN_HZ || duty_ns > NS_IN_HZ)
 207                 return -ERANGE;
 208
 209         if (duty_ns > period_ns)
 210                 return -EINVAL;
 211
 212         if (period_ns == pwm->period_ns &&
 213             duty_ns == pwm->duty_ns)
 214                 return 0;
 215
 216         /* The TCMP and TCNT can be read without a lock, they're not
 217          * shared between the timers. */
 218
 219         tcmp = __raw_readl(S3C2410_TCMPB(pwm->pwm_id));
 220         tcnt = __raw_readl(S3C2410_TCNTB(pwm->pwm_id));
 221
 222         period = NS_IN_HZ / period_ns;
 223
 224         pwm_dbg(pwm, "duty_ns=%d, period_ns=%d (%lu)\n",
 225                 duty_ns, period_ns, period);
 226
 227         /* Check to see if we are changing the clock rate of the PWM */
 228
 229         if (pwm->period_ns != period_ns) {
 230                 if (pwm_is_tdiv(pwm)) {
 231                         tin_rate = pwm_calc_tin(pwm, period);
 232                         clk_set_rate(pwm->clk_div, tin_rate);
 233                 } else
 234                         tin_rate = clk_get_rate(pwm->clk);
 235
 236                 pwm->period_ns = period_ns;
 237
 238                 pwm_dbg(pwm, "tin_rate=%lu\n", tin_rate);
 239
 240                 tin_ns = NS_IN_HZ / tin_rate;
 241                 tcnt = period_ns / tin_ns;
 242         } else
 243                 tin_ns = NS_IN_HZ / clk_get_rate(pwm->clk);
 244
 245         /* Note, counters count down */
 246
 247         tcmp = duty_ns / tin_ns;
 248         tcmp = tcnt - tcmp;
 249         /* the pwm hw only checks the compare register after a decrement,
 250            so the pin never toggles if tcmp = tcnt */
 251         if (tcmp == tcnt)
 252                 tcmp--;
 253
 254         pwm_dbg(pwm, "tin_ns=%lu, tcmp=%ld/%lu\n", tin_ns, tcmp, tcnt);
 255
 256         if (tcmp < 0)
 257                 tcmp = 0;
 258
 259         /* Update the PWM register block. */
 260
 261         local_irq_save(flags);
 262
 263         __raw_writel(tcmp, S3C2410_TCMPB(pwm->pwm_id));
 264         __raw_writel(tcnt, S3C2410_TCNTB(pwm->pwm_id));
 265
 266         tcon = __raw_readl(S3C2410_TCON);
 267         tcon |= pwm_tcon_manulupdate(pwm);
 268         tcon |= pwm_tcon_autoreload(pwm);
 269         __raw_writel(tcon, S3C2410_TCON);
 270
 271         tcon &= ~pwm_tcon_manulupdate(pwm);
 272         __raw_writel(tcon, S3C2410_TCON);
 273
 274         local_irq_restore(flags);
 275
 276         return 0;
 277 }
 278
 279 EXPORT_SYMBOL(pwm_config);
 280
 281 static int pwm_register(struct pwm_device *pwm)
 282 {
 283         pwm->duty_ns = -1;
 284         pwm->period_ns = -1;
 285
 286         mutex_lock(&pwm_lock);
 287         list_add_tail(&pwm->list, &pwm_list);
 288         mutex_unlock(&pwm_lock);
 289
 290         return 0;
 291 }
 292
 293 static int s3c_pwm_probe(struct platform_device *pdev)
 294 {
 295         struct device *dev = &pdev->dev;
 296         struct pwm_device *pwm;
 297         unsigned long flags;
 298         unsigned long tcon;
 299         unsigned int id = pdev->id;
 300         int ret;
 301
 302         if (id == 4) {
 303                 dev_err(dev, "TIMER4 is currently not supported\n");
 304                 return -ENXIO;
 305         }
 306
 307         pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
 308         if (pwm == NULL) {
 309                 dev_err(dev, "failed to allocate pwm_device\n");
 310                 return -ENOMEM;
 311         }
 312
 313         pwm->pdev = pdev;
 314         pwm->pwm_id = id;
 315
 316         /* calculate base of control bits in TCON */
 317         pwm->tcon_base = id == 0 ? 0 : (id * 4) + 4;
 318
 319         pwm->clk = clk_get(dev, "pwm-tin");
 320         if (IS_ERR(pwm->clk)) {
 321                 dev_err(dev, "failed to get pwm tin clk\n");
 322                 ret = PTR_ERR(pwm->clk);
 323                 goto err_alloc;
 324         }
 325
 326         pwm->clk_div = clk_get(dev, "pwm-tdiv");
 327         if (IS_ERR(pwm->clk_div)) {
 328                 dev_err(dev, "failed to get pwm tdiv clk\n");
 329                 ret = PTR_ERR(pwm->clk_div);
 330                 goto err_clk_tin;
 331         }
 332
 333         local_irq_save(flags);
 334
 335         tcon = __raw_readl(S3C2410_TCON);
 336         tcon |= pwm_tcon_invert(pwm);
 337         __raw_writel(tcon, S3C2410_TCON);
 338
 339         local_irq_restore(flags);
 340
 341
 342         ret = pwm_register(pwm);
 343         if (ret) {
 344                 dev_err(dev, "failed to register pwm\n");
 345                 goto err_clk_tdiv;
 346         }
 347
 348         pwm_dbg(pwm, "config bits %02x\n",
 349                 (__raw_readl(S3C2410_TCON) >> pwm->tcon_base) & 0x0f);
 350
 351         dev_info(dev, "tin at %lu, tdiv at %lu, tin=%sclk, base %d\n",
 352                  clk_get_rate(pwm->clk),
 353                  clk_get_rate(pwm->clk_div),
 354                  pwm_is_tdiv(pwm) ? "div" : "ext", pwm->tcon_base);
 355
 356         platform_set_drvdata(pdev, pwm);
 357         return 0;
 358
 359  err_clk_tdiv:
 360         clk_put(pwm->clk_div);
 361
 362  err_clk_tin:
 363         clk_put(pwm->clk);
 364
 365  err_alloc:
 366         kfree(pwm);
 367         return ret;
 368 }
 369
 370 static int s3c_pwm_remove(struct platform_device *pdev)
 371 {
 372         struct pwm_device *pwm = platform_get_drvdata(pdev);
 373
 374         clk_put(pwm->clk_div);
 375         clk_put(pwm->clk);
 376         kfree(pwm);
 377
 378         return 0;
 379 }
 380
 381 static struct platform_driver s3c_pwm_driver = {
 382         .driver         = {
 383                 .name   = "s3c24xx-pwm",
 384                 .owner  = THIS_MODULE,
 385         },
 386         .probe          = s3c_pwm_probe,
 387         .remove         = __devexit_p(s3c_pwm_remove),
 388 };
 389
 390 static int __init pwm_init(void)
 391 {
 392         int ret;
 393
 394         clk_scaler[0] = clk_get(NULL, "pwm-scaler0");
 395         clk_scaler[1] = clk_get(NULL, "pwm-scaler1");
 396
 397         if (IS_ERR(clk_scaler[0]) || IS_ERR(clk_scaler[1])) {
 398                 printk(KERN_ERR "%s: failed to get scaler clocks\n", __func__);
 399                 return -EINVAL;
 400         }
 401
 402         ret = platform_driver_register(&s3c_pwm_driver);
 403         if (ret)
 404                 printk(KERN_ERR "%s: failed to add pwm driver\n", __func__);
 405
 406         return ret;
 407 }
 408
 409 arch_initcall(pwm_init);