drivers/pwm/pwm-samsung.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/export.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 s3c_chip {
  28         struct platform_device  *pdev;
  29
  30         struct clk              *clk_div;
  31         struct clk              *clk;
  32         const char              *label;
  33
  34         unsigned int             period_ns;
  35         unsigned int             duty_ns;
  36
  37         unsigned char            tcon_base;
  38         unsigned char            pwm_id;
  39         struct pwm_chip          chip;
  40 };
  41
  42 #define to_s3c_chip(chip)       container_of(chip, struct s3c_chip, chip)
  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 s3c_chip *chip)
  49 {
  50         return clk_get_parent(chip->clk) == chip->clk_div;
  51 }
  52
  53 #define pwm_tcon_start(pwm) (1 << (pwm->tcon_base + 0))
  54 #define pwm_tcon_invert(pwm) (1 << (pwm->tcon_base + 2))
  55 #define pwm_tcon_autoreload(pwm) (1 << (pwm->tcon_base + 3))
  56 #define pwm_tcon_manulupdate(pwm) (1 << (pwm->tcon_base + 1))
  57
  58 static int s3c_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  59 {
  60         struct s3c_chip *s3c = to_s3c_chip(chip);
  61         unsigned long flags;
  62         unsigned long tcon;
  63
  64         local_irq_save(flags);
  65
  66         tcon = __raw_readl(S3C2410_TCON);
  67         tcon |= pwm_tcon_start(s3c);
  68         __raw_writel(tcon, S3C2410_TCON);
  69
  70         local_irq_restore(flags);
  71
  72         return 0;
  73 }
  74
  75 static void s3c_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
  76 {
  77         struct s3c_chip *s3c = to_s3c_chip(chip);
  78         unsigned long flags;
  79         unsigned long tcon;
  80
  81         local_irq_save(flags);
  82
  83         tcon = __raw_readl(S3C2410_TCON);
  84         tcon &= ~pwm_tcon_start(s3c);
  85         __raw_writel(tcon, S3C2410_TCON);
  86
  87         local_irq_restore(flags);
  88 }
  89
  90 static unsigned long pwm_calc_tin(struct s3c_chip *s3c, unsigned long freq)
  91 {
  92         unsigned long tin_parent_rate;
  93         unsigned int div;
  94
  95         tin_parent_rate = clk_get_rate(clk_get_parent(s3c->clk_div));
  96         pwm_dbg(s3c, "tin parent at %lu\n", tin_parent_rate);
  97
  98         for (div = 2; div <= 16; div *= 2) {
  99                 if ((tin_parent_rate / (div << 16)) < freq)
 100                         return tin_parent_rate / div;
 101         }
 102
 103         return tin_parent_rate / 16;
 104 }
 105
 106 #define NS_IN_HZ (1000000000UL)
 107
 108 static int s3c_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 109                 int duty_ns, int period_ns)
 110 {
 111         struct s3c_chip *s3c = to_s3c_chip(chip);
 112         unsigned long tin_rate;
 113         unsigned long tin_ns;
 114         unsigned long period;
 115         unsigned long flags;
 116         unsigned long tcon;
 117         unsigned long tcnt;
 118         long tcmp;
 119
 120         /* We currently avoid using 64bit arithmetic by using the
 121          * fact that anything faster than 1Hz is easily representable
 122          * by 32bits. */
 123
 124         if (period_ns > NS_IN_HZ || duty_ns > NS_IN_HZ)
 125                 return -ERANGE;
 126
 127         if (duty_ns > period_ns)
 128                 return -EINVAL;
 129
 130         if (period_ns == s3c->period_ns &&
 131             duty_ns == s3c->duty_ns)
 132                 return 0;
 133
 134         /* The TCMP and TCNT can be read without a lock, they're not
 135          * shared between the timers. */
 136
 137         tcmp = __raw_readl(S3C2410_TCMPB(s3c->pwm_id));
 138         tcnt = __raw_readl(S3C2410_TCNTB(s3c->pwm_id));
 139
 140         period = NS_IN_HZ / period_ns;
 141
 142         pwm_dbg(s3c, "duty_ns=%d, period_ns=%d (%lu)\n",
 143                 duty_ns, period_ns, period);
 144
 145         /* Check to see if we are changing the clock rate of the PWM */
 146
 147         if (s3c->period_ns != period_ns) {
 148                 if (pwm_is_tdiv(s3c)) {
 149                         tin_rate = pwm_calc_tin(s3c, period);
 150                         clk_set_rate(s3c->clk_div, tin_rate);
 151                 } else
 152                         tin_rate = clk_get_rate(s3c->clk);
 153
 154                 s3c->period_ns = period_ns;
 155
 156                 pwm_dbg(s3c, "tin_rate=%lu\n", tin_rate);
 157
 158                 tin_ns = NS_IN_HZ / tin_rate;
 159                 tcnt = period_ns / tin_ns;
 160         } else
 161                 tin_ns = NS_IN_HZ / clk_get_rate(s3c->clk);
 162
 163         /* Note, counters count down */
 164
 165         tcmp = duty_ns / tin_ns;
 166         tcmp = tcnt - tcmp;
 167         /* the pwm hw only checks the compare register after a decrement,
 168            so the pin never toggles if tcmp = tcnt */
 169         if (tcmp == tcnt)
 170                 tcmp--;
 171
 172         pwm_dbg(s3c, "tin_ns=%lu, tcmp=%ld/%lu\n", tin_ns, tcmp, tcnt);
 173
 174         if (tcmp < 0)
 175                 tcmp = 0;
 176
 177         /* Update the PWM register block. */
 178
 179         local_irq_save(flags);
 180
 181         __raw_writel(tcmp, S3C2410_TCMPB(s3c->pwm_id));
 182         __raw_writel(tcnt, S3C2410_TCNTB(s3c->pwm_id));
 183
 184         tcon = __raw_readl(S3C2410_TCON);
 185         tcon |= pwm_tcon_manulupdate(s3c);
 186         tcon |= pwm_tcon_autoreload(s3c);
 187         __raw_writel(tcon, S3C2410_TCON);
 188
 189         tcon &= ~pwm_tcon_manulupdate(s3c);
 190         __raw_writel(tcon, S3C2410_TCON);
 191
 192         local_irq_restore(flags);
 193
 194         return 0;
 195 }
 196
 197 static struct pwm_ops s3c_pwm_ops = {
 198         .enable = s3c_pwm_enable,
 199         .disable = s3c_pwm_disable,
 200         .config = s3c_pwm_config,
 201         .owner = THIS_MODULE,
 202 };
 203
 204 static int s3c_pwm_probe(struct platform_device *pdev)
 205 {
 206         struct device *dev = &pdev->dev;
 207         struct s3c_chip *s3c;
 208         unsigned long flags;
 209         unsigned long tcon;
 210         unsigned int id = pdev->id;
 211         int ret;
 212
 213         if (id == 4) {
 214                 dev_err(dev, "TIMER4 is currently not supported\n");
 215                 return -ENXIO;
 216         }
 217
 218         s3c = kzalloc(sizeof(*s3c), GFP_KERNEL);
 219         if (s3c == NULL) {
 220                 dev_err(dev, "failed to allocate pwm_device\n");
 221                 return -ENOMEM;
 222         }
 223
 224         /* calculate base of control bits in TCON */
 225         s3c->tcon_base = id == 0 ? 0 : (id * 4) + 4;
 226         s3c->chip.ops = &s3c_pwm_ops;
 227         s3c->chip.base = -1;
 228         s3c->chip.npwm = 1;
 229
 230         s3c->clk = clk_get(dev, "pwm-tin");
 231         if (IS_ERR(s3c->clk)) {
 232                 dev_err(dev, "failed to get pwm tin clk\n");
 233                 ret = PTR_ERR(s3c->clk);
 234                 goto err_alloc;
 235         }
 236
 237         s3c->clk_div = clk_get(dev, "pwm-tdiv");
 238         if (IS_ERR(s3c->clk_div)) {
 239                 dev_err(dev, "failed to get pwm tdiv clk\n");
 240                 ret = PTR_ERR(s3c->clk_div);
 241                 goto err_clk_tin;
 242         }
 243
 244         clk_enable(s3c->clk);
 245         clk_enable(s3c->clk_div);
 246
 247         local_irq_save(flags);
 248
 249         tcon = __raw_readl(S3C2410_TCON);
 250         tcon |= pwm_tcon_invert(s3c);
 251         __raw_writel(tcon, S3C2410_TCON);
 252
 253         local_irq_restore(flags);
 254
 255         ret = pwmchip_add(&s3c->chip);
 256         if (ret < 0) {
 257                 dev_err(dev, "failed to register pwm\n");
 258                 goto err_clk_tdiv;
 259         }
 260
 261         pwm_dbg(s3c, "config bits %02x\n",
 262                 (__raw_readl(S3C2410_TCON) >> s3c->tcon_base) & 0x0f);
 263
 264         dev_info(dev, "tin at %lu, tdiv at %lu, tin=%sclk, base %d\n",
 265                  clk_get_rate(s3c->clk),
 266                  clk_get_rate(s3c->clk_div),
 267                  pwm_is_tdiv(s3c) ? "div" : "ext", s3c->tcon_base);
 268
 269         platform_set_drvdata(pdev, s3c);
 270         return 0;
 271
 272  err_clk_tdiv:
 273         clk_disable(s3c->clk_div);
 274         clk_disable(s3c->clk);
 275         clk_put(s3c->clk_div);
 276
 277  err_clk_tin:
 278         clk_put(s3c->clk);
 279
 280  err_alloc:
 281         kfree(s3c);
 282         return ret;
 283 }
 284
 285 static int __devexit s3c_pwm_remove(struct platform_device *pdev)
 286 {
 287         struct s3c_chip *s3c = platform_get_drvdata(pdev);
 288         int err;
 289
 290         err = pwmchip_remove(&s3c->chip);
 291         if (err < 0)
 292                 return err;
 293
 294         clk_disable(s3c->clk_div);
 295         clk_disable(s3c->clk);
 296         clk_put(s3c->clk_div);
 297         clk_put(s3c->clk);
 298         kfree(s3c);
 299
 300         return 0;
 301 }
 302
 303 #ifdef CONFIG_PM
 304 static int s3c_pwm_suspend(struct platform_device *pdev, pm_message_t state)
 305 {
 306         struct s3c_chip *s3c = platform_get_drvdata(pdev);
 307
 308         /* No one preserve these values during suspend so reset them
 309          * Otherwise driver leaves PWM unconfigured if same values
 310          * passed to pwm_config
 311          */
 312         s3c->period_ns = 0;
 313         s3c->duty_ns = 0;
 314
 315         return 0;
 316 }
 317
 318 static int s3c_pwm_resume(struct platform_device *pdev)
 319 {
 320         struct s3c_chip *s3c = platform_get_drvdata(pdev);
 321         unsigned long tcon;
 322
 323         /* Restore invertion */
 324         tcon = __raw_readl(S3C2410_TCON);
 325         tcon |= pwm_tcon_invert(s3c);
 326         __raw_writel(tcon, S3C2410_TCON);
 327
 328         return 0;
 329 }
 330
 331 #else
 332 #define s3c_pwm_suspend NULL
 333 #define s3c_pwm_resume NULL
 334 #endif
 335
 336 static struct platform_driver s3c_pwm_driver = {
 337         .driver         = {
 338                 .name   = "s3c24xx-pwm",
 339                 .owner  = THIS_MODULE,
 340         },
 341         .probe          = s3c_pwm_probe,
 342         .remove         = __devexit_p(s3c_pwm_remove),
 343         .suspend        = s3c_pwm_suspend,
 344         .resume         = s3c_pwm_resume,
 345 };
 346
 347 static int __init pwm_init(void)
 348 {
 349         int ret;
 350
 351         clk_scaler[0] = clk_get(NULL, "pwm-scaler0");
 352         clk_scaler[1] = clk_get(NULL, "pwm-scaler1");
 353
 354         if (IS_ERR(clk_scaler[0]) || IS_ERR(clk_scaler[1])) {
 355                 printk(KERN_ERR "%s: failed to get scaler clocks\n", __func__);
 356                 return -EINVAL;
 357         }
 358
 359         ret = platform_driver_register(&s3c_pwm_driver);
 360         if (ret)
 361                 printk(KERN_ERR "%s: failed to add pwm driver\n", __func__);
 362
 363         return ret;
 364 }
 365
 366 arch_initcall(pwm_init);