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