arch/arm/plat-s3c/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/err.h>
  18 #include <linux/clk.h>
  19 #include <linux/io.h>
  20 #include <linux/pwm.h>
  21
  22 #include <mach/irqs.h>
  23 #include <mach/map.h>
  24
  25 #include <plat/devs.h>
  26 #include <plat/regs-timer.h>
  27
  28 struct pwm_device {
  29         struct list_head         list;
  30         struct platform_device  *pdev;
  31
  32         struct clk              *clk_div;
  33         struct clk              *clk;
  34         const char              *label;
  35
  36         unsigned int             period_ns;
  37         unsigned int             duty_ns;
  38
  39         unsigned char            tcon_base;
  40         unsigned char            running;
  41         unsigned char            use_count;
  42         unsigned char            pwm_id;
  43 };
  44
  45 #define pwm_dbg(_pwm, msg...) dev_dbg(&(_pwm)->pdev->dev, msg)
  46
  47 static struct clk *clk_scaler[2];
  48
  49 /* Standard setup for a timer block. */
  50
  51 #define TIMER_RESOURCE_SIZE (1)
  52
  53 #define TIMER_RESOURCE(_tmr, _irq)                      \
  54         (struct resource [TIMER_RESOURCE_SIZE]) {       \
  55                 [0] = {                                 \
  56                         .start  = _irq,                 \
  57                         .end    = _irq,                 \
  58                         .flags  = IORESOURCE_IRQ        \
  59                 }                                       \
  60         }
  61
  62 #define DEFINE_S3C_TIMER(_tmr_no, _irq)                 \
  63         .name           = "s3c24xx-pwm",                \
  64         .id             = _tmr_no,                      \
  65         .num_resources  = TIMER_RESOURCE_SIZE,          \
  66         .resource       = TIMER_RESOURCE(_tmr_no, _irq),        \
  67
  68 /* since we already have an static mapping for the timer, we do not
  69  * bother setting any IO resource for the base.
  70  */
  71
  72 struct platform_device s3c_device_timer[] = {
  73         [0] = { DEFINE_S3C_TIMER(0, IRQ_TIMER0) },
  74         [1] = { DEFINE_S3C_TIMER(1, IRQ_TIMER1) },
  75         [2] = { DEFINE_S3C_TIMER(2, IRQ_TIMER2) },
  76         [3] = { DEFINE_S3C_TIMER(3, IRQ_TIMER3) },
  77         [4] = { DEFINE_S3C_TIMER(4, IRQ_TIMER4) },
  78 };
  79
  80 static inline int pwm_is_tdiv(struct pwm_device *pwm)
  81 {
  82         return clk_get_parent(pwm->clk) == pwm->clk_div;
  83 }
  84
  85 static DEFINE_MUTEX(pwm_lock);
  86 static LIST_HEAD(pwm_list);
  87
  88 struct pwm_device *pwm_request(int pwm_id, const char *label)
  89 {
  90         struct pwm_device *pwm;
  91         int found = 0;
  92
  93         mutex_lock(&pwm_lock);
  94
  95         list_for_each_entry(pwm, &pwm_list, list) {
  96                 if (pwm->pwm_id == pwm_id) {
  97                         found = 1;
  98                         break;
  99                 }
 100         }
 101
 102         if (found) {
 103                 if (pwm->use_count == 0) {
 104                         pwm->use_count = 1;
 105                         pwm->label = label;
 106                 } else
 107                         pwm = ERR_PTR(-EBUSY);
 108         } else
 109                 pwm = ERR_PTR(-ENOENT);
 110
 111         mutex_unlock(&pwm_lock);
 112         return pwm;
 113 }
 114
 115 EXPORT_SYMBOL(pwm_request);
 116
 117
 118 void pwm_free(struct pwm_device *pwm)
 119 {
 120         mutex_lock(&pwm_lock);
 121
 122         if (pwm->use_count) {
 123                 pwm->use_count--;
 124                 pwm->label = NULL;
 125         } else
 126                 printk(KERN_ERR "PWM%d device already freed\n", pwm->pwm_id);
 127
 128         mutex_unlock(&pwm_lock);
 129 }
 130
 131 EXPORT_SYMBOL(pwm_free);
 132
 133 #define pwm_tcon_start(pwm) (1 << (pwm->tcon_base + 0))
 134 #define pwm_tcon_invert(pwm) (1 << (pwm->tcon_base + 2))
 135 #define pwm_tcon_autoreload(pwm) (1 << (pwm->tcon_base + 3))
 136 #define pwm_tcon_manulupdate(pwm) (1 << (pwm->tcon_base + 1))
 137
 138 int pwm_enable(struct pwm_device *pwm)
 139 {
 140         unsigned long flags;
 141         unsigned long tcon;
 142
 143         local_irq_save(flags);
 144
 145         tcon = __raw_readl(S3C2410_TCON);
 146         tcon |= pwm_tcon_start(pwm);
 147         __raw_writel(tcon, S3C2410_TCON);
 148
 149         local_irq_restore(flags);
 150
 151         pwm->running = 1;
 152         return 0;
 153 }
 154
 155 EXPORT_SYMBOL(pwm_enable);
 156
 157 void pwm_disable(struct pwm_device *pwm)
 158 {
 159         unsigned long flags;
 160         unsigned long tcon;
 161
 162         local_irq_save(flags);
 163
 164         tcon = __raw_readl(S3C2410_TCON);
 165         tcon &= ~pwm_tcon_start(pwm);
 166         __raw_writel(tcon, S3C2410_TCON);
 167
 168         local_irq_restore(flags);
 169
 170         pwm->running = 0;
 171 }
 172
 173 EXPORT_SYMBOL(pwm_disable);
 174
 175 static unsigned long pwm_calc_tin(struct pwm_device *pwm, unsigned long freq)
 176 {
 177         unsigned long tin_parent_rate;
 178         unsigned int div;
 179
 180         tin_parent_rate = clk_get_rate(clk_get_parent(pwm->clk_div));
 181         pwm_dbg(pwm, "tin parent at %lu\n", tin_parent_rate);
 182
 183         for (div = 2; div <= 16; div *= 2) {
 184                 if ((tin_parent_rate / (div << 16)) < freq)
 185                         return tin_parent_rate / div;
 186         }
 187
 188         return tin_parent_rate / 16;
 189 }
 190
 191 #define NS_IN_HZ (1000000000UL)
 192
 193 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
 194 {
 195         unsigned long tin_rate;
 196         unsigned long tin_ns;
 197         unsigned long period;
 198         unsigned long flags;
 199         unsigned long tcon;
 200         unsigned long tcnt;
 201         long tcmp;
 202
 203         /* We currently avoid using 64bit arithmetic by using the
 204          * fact that anything faster than 1Hz is easily representable
 205          * by 32bits. */
 206
 207         if (period_ns > NS_IN_HZ || duty_ns > NS_IN_HZ)
 208                 return -ERANGE;
 209
 210         if (duty_ns > period_ns)
 211                 return -EINVAL;
 212
 213         if (period_ns == pwm->period_ns &&
 214             duty_ns == pwm->duty_ns)
 215                 return 0;
 216
 217         /* The TCMP and TCNT can be read without a lock, they're not
 218          * shared between the timers. */
 219
 220         tcmp = __raw_readl(S3C2410_TCMPB(pwm->pwm_id));
 221         tcnt = __raw_readl(S3C2410_TCNTB(pwm->pwm_id));
 222
 223         period = NS_IN_HZ / period_ns;
 224
 225         pwm_dbg(pwm, "duty_ns=%d, period_ns=%d (%lu)\n",
 226                 duty_ns, period_ns, period);
 227
 228         /* Check to see if we are changing the clock rate of the PWM */
 229
 230         if (pwm->period_ns != period_ns) {
 231                 if (pwm_is_tdiv(pwm)) {
 232                         tin_rate = pwm_calc_tin(pwm, period);
 233                         clk_set_rate(pwm->clk_div, tin_rate);
 234                 } else
 235                         tin_rate = clk_get_rate(pwm->clk);
 236
 237                 pwm->period_ns = period_ns;
 238
 239                 pwm_dbg(pwm, "tin_rate=%lu\n", tin_rate);
 240
 241                 tin_ns = NS_IN_HZ / tin_rate;
 242                 tcnt = period_ns / tin_ns;
 243         } else
 244                 tin_ns = NS_IN_HZ / clk_get_rate(pwm->clk);
 245
 246         /* Note, counters count down */
 247
 248         tcmp = duty_ns / tin_ns;
 249         tcmp = tcnt - tcmp;
 250         /* the pwm hw only checks the compare register after a decrement,
 251            so the pin never toggles if tcmp = tcnt */
 252         if (tcmp == tcnt)
 253                 tcmp--;
 254
 255         pwm_dbg(pwm, "tin_ns=%lu, tcmp=%ld/%lu\n", tin_ns, tcmp, tcnt);
 256
 257         if (tcmp < 0)
 258                 tcmp = 0;
 259
 260         /* Update the PWM register block. */
 261
 262         local_irq_save(flags);
 263
 264         __raw_writel(tcmp, S3C2410_TCMPB(pwm->pwm_id));
 265         __raw_writel(tcnt, S3C2410_TCNTB(pwm->pwm_id));
 266
 267         tcon = __raw_readl(S3C2410_TCON);
 268         tcon |= pwm_tcon_manulupdate(pwm);
 269         tcon |= pwm_tcon_autoreload(pwm);
 270         __raw_writel(tcon, S3C2410_TCON);
 271
 272         tcon &= ~pwm_tcon_manulupdate(pwm);
 273         __raw_writel(tcon, S3C2410_TCON);
 274
 275         local_irq_restore(flags);
 276
 277         return 0;
 278 }
 279
 280 EXPORT_SYMBOL(pwm_config);
 281
 282 static int pwm_register(struct pwm_device *pwm)
 283 {
 284         pwm->duty_ns = -1;
 285         pwm->period_ns = -1;
 286
 287         mutex_lock(&pwm_lock);
 288         list_add_tail(&pwm->list, &pwm_list);
 289         mutex_unlock(&pwm_lock);
 290
 291         return 0;
 292 }
 293
 294 static int s3c_pwm_probe(struct platform_device *pdev)
 295 {
 296         struct device *dev = &pdev->dev;
 297         struct pwm_device *pwm;
 298         unsigned long flags;
 299         unsigned long tcon;
 300         unsigned int id = pdev->id;
 301         int ret;
 302
 303         if (id == 4) {
 304                 dev_err(dev, "TIMER4 is currently not supported\n");
 305                 return -ENXIO;
 306         }
 307
 308         pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
 309         if (pwm == NULL) {
 310                 dev_err(dev, "failed to allocate pwm_device\n");
 311                 return -ENOMEM;
 312         }
 313
 314         pwm->pdev = pdev;
 315         pwm->pwm_id = id;
 316
 317         /* calculate base of control bits in TCON */
 318         pwm->tcon_base = id == 0 ? 0 : (id * 4) + 4;
 319
 320         pwm->clk = clk_get(dev, "pwm-tin");
 321         if (IS_ERR(pwm->clk)) {
 322                 dev_err(dev, "failed to get pwm tin clk\n");
 323                 ret = PTR_ERR(pwm->clk);
 324                 goto err_alloc;
 325         }
 326
 327         pwm->clk_div = clk_get(dev, "pwm-tdiv");
 328         if (IS_ERR(pwm->clk_div)) {
 329                 dev_err(dev, "failed to get pwm tdiv clk\n");
 330                 ret = PTR_ERR(pwm->clk_div);
 331                 goto err_clk_tin;
 332         }
 333
 334         local_irq_save(flags);
 335
 336         tcon = __raw_readl(S3C2410_TCON);
 337         tcon |= pwm_tcon_invert(pwm);
 338         __raw_writel(tcon, S3C2410_TCON);
 339
 340         local_irq_restore(flags);
 341
 342
 343         ret = pwm_register(pwm);
 344         if (ret) {
 345                 dev_err(dev, "failed to register pwm\n");
 346                 goto err_clk_tdiv;
 347         }
 348
 349         pwm_dbg(pwm, "config bits %02x\n",
 350                 (__raw_readl(S3C2410_TCON) >> pwm->tcon_base) & 0x0f);
 351
 352         dev_info(dev, "tin at %lu, tdiv at %lu, tin=%sclk, base %d\n",
 353                  clk_get_rate(pwm->clk),
 354                  clk_get_rate(pwm->clk_div),
 355                  pwm_is_tdiv(pwm) ? "div" : "ext", pwm->tcon_base);
 356
 357         platform_set_drvdata(pdev, pwm);
 358         return 0;
 359
 360  err_clk_tdiv:
 361         clk_put(pwm->clk_div);
 362
 363  err_clk_tin:
 364         clk_put(pwm->clk);
 365
 366  err_alloc:
 367         kfree(pwm);
 368         return ret;
 369 }
 370
 371 static int s3c_pwm_remove(struct platform_device *pdev)
 372 {
 373         struct pwm_device *pwm = platform_get_drvdata(pdev);
 374
 375         clk_put(pwm->clk_div);
 376         clk_put(pwm->clk);
 377         kfree(pwm);
 378
 379         return 0;
 380 }
 381
 382 static struct platform_driver s3c_pwm_driver = {
 383         .driver         = {
 384                 .name   = "s3c24xx-pwm",
 385                 .owner  = THIS_MODULE,
 386         },
 387         .probe          = s3c_pwm_probe,
 388         .remove         = __devexit_p(s3c_pwm_remove),
 389 };
 390
 391 static int __init pwm_init(void)
 392 {
 393         int ret;
 394
 395         clk_scaler[0] = clk_get(NULL, "pwm-scaler0");
 396         clk_scaler[1] = clk_get(NULL, "pwm-scaler1");
 397
 398         if (IS_ERR(clk_scaler[0]) || IS_ERR(clk_scaler[1])) {
 399                 printk(KERN_ERR "%s: failed to get scaler clocks\n", __func__);
 400                 return -EINVAL;
 401         }
 402
 403         ret = platform_driver_register(&s3c_pwm_driver);
 404         if (ret)
 405                 printk(KERN_ERR "%s: failed to add pwm driver\n", __func__);
 406
 407         return ret;
 408 }
 409
 410 arch_initcall(pwm_init);