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