drivers/pwm/pwm-samsung.c

   1 /* drivers/pwm/pwm-samsung.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 #define pr_fmt(fmt) "pwm-samsung: " fmt
  15
  16 #include <linux/export.h>
  17 #include <linux/kernel.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/slab.h>
  20 #include <linux/err.h>
  21 #include <linux/clk.h>
  22 #include <linux/io.h>
  23 #include <linux/pwm.h>
  24
  25 #include <mach/map.h>
  26
  27 #include <plat/regs-timer.h>
  28
  29 struct s3c_chip {
  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            pwm_id;
  41         struct pwm_chip          chip;
  42 };
  43
  44 #define to_s3c_chip(chip)       container_of(chip, struct s3c_chip, chip)
  45
  46 #define pwm_dbg(_pwm, msg...) dev_dbg(&(_pwm)->pdev->dev, msg)
  47
  48 static struct clk *clk_scaler[2];
  49
  50 static inline int pwm_is_tdiv(struct s3c_chip *chip)
  51 {
  52         return clk_get_parent(chip->clk) == chip->clk_div;
  53 }
  54
  55 #define pwm_tcon_start(pwm) (1 << (pwm->tcon_base + 0))
  56 #define pwm_tcon_invert(pwm) (1 << (pwm->tcon_base + 2))
  57 #define pwm_tcon_autoreload(pwm) (1 << (pwm->tcon_base + 3))
  58 #define pwm_tcon_manulupdate(pwm) (1 << (pwm->tcon_base + 1))
  59
  60 static int s3c_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  61 {
  62         struct s3c_chip *s3c = to_s3c_chip(chip);
  63         unsigned long flags;
  64         unsigned long tcon;
  65
  66         local_irq_save(flags);
  67
  68         tcon = __raw_readl(S3C2410_TCON);
  69         tcon |= pwm_tcon_start(s3c);
  70         __raw_writel(tcon, S3C2410_TCON);
  71
  72         local_irq_restore(flags);
  73
  74         return 0;
  75 }
  76
  77 static void s3c_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
  78 {
  79         struct s3c_chip *s3c = to_s3c_chip(chip);
  80         unsigned long flags;
  81         unsigned long tcon;
  82
  83         local_irq_save(flags);
  84
  85         tcon = __raw_readl(S3C2410_TCON);
  86         tcon &= ~pwm_tcon_start(s3c);
  87         __raw_writel(tcon, S3C2410_TCON);
  88
  89         local_irq_restore(flags);
  90 }
  91
  92 static unsigned long pwm_calc_tin(struct s3c_chip *s3c, unsigned long freq)
  93 {
  94         unsigned long tin_parent_rate;
  95         unsigned int div;
  96
  97         tin_parent_rate = clk_get_rate(clk_get_parent(s3c->clk_div));
  98         pwm_dbg(s3c, "tin parent at %lu\n", tin_parent_rate);
  99
 100         for (div = 2; div <= 16; div *= 2) {
 101                 if ((tin_parent_rate / (div << 16)) < freq)
 102                         return tin_parent_rate / div;
 103         }
 104
 105         return tin_parent_rate / 16;
 106 }
 107
 108 #define NS_IN_HZ (1000000000UL)
 109
 110 static int s3c_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 111                 int duty_ns, int period_ns)
 112 {
 113         struct s3c_chip *s3c = to_s3c_chip(chip);
 114         unsigned long tin_rate;
 115         unsigned long tin_ns;
 116         unsigned long period;
 117         unsigned long flags;
 118         unsigned long tcon;
 119         unsigned long tcnt;
 120         long tcmp;
 121
 122         /* We currently avoid using 64bit arithmetic by using the
 123          * fact that anything faster than 1Hz is easily representable
 124          * by 32bits. */
 125
 126         if (period_ns > NS_IN_HZ || duty_ns > NS_IN_HZ)
 127                 return -ERANGE;
 128
 129         if (period_ns == s3c->period_ns &&
 130             duty_ns == s3c->duty_ns)
 131                 return 0;
 132
 133         /* The TCMP and TCNT can be read without a lock, they're not
 134          * shared between the timers. */
 135
 136         tcmp = __raw_readl(S3C2410_TCMPB(s3c->pwm_id));
 137         tcnt = __raw_readl(S3C2410_TCNTB(s3c->pwm_id));
 138
 139         period = NS_IN_HZ / period_ns;
 140
 141         pwm_dbg(s3c, "duty_ns=%d, period_ns=%d (%lu)\n",
 142                 duty_ns, period_ns, period);
 143
 144         /* Check to see if we are changing the clock rate of the PWM */
 145
 146         if (s3c->period_ns != period_ns) {
 147                 if (pwm_is_tdiv(s3c)) {
 148                         tin_rate = pwm_calc_tin(s3c, period);
 149                         clk_set_rate(s3c->clk_div, tin_rate);
 150                 } else
 151                         tin_rate = clk_get_rate(s3c->clk);
 152
 153                 s3c->period_ns = period_ns;
 154
 155                 pwm_dbg(s3c, "tin_rate=%lu\n", tin_rate);
 156
 157                 tin_ns = NS_IN_HZ / tin_rate;
 158                 tcnt = period_ns / tin_ns;
 159         } else
 160                 tin_ns = NS_IN_HZ / clk_get_rate(s3c->clk);
 161
 162         /* Note, counters count down */
 163
 164         tcmp = duty_ns / tin_ns;
 165         tcmp = tcnt - tcmp;
 166         /* the pwm hw only checks the compare register after a decrement,
 167            so the pin never toggles if tcmp = tcnt */
 168         if (tcmp == tcnt)
 169                 tcmp--;
 170
 171         pwm_dbg(s3c, "tin_ns=%lu, tcmp=%ld/%lu\n", tin_ns, tcmp, tcnt);
 172
 173         if (tcmp < 0)
 174                 tcmp = 0;
 175
 176         /* Update the PWM register block. */
 177
 178         local_irq_save(flags);
 179
 180         __raw_writel(tcmp, S3C2410_TCMPB(s3c->pwm_id));
 181         __raw_writel(tcnt, S3C2410_TCNTB(s3c->pwm_id));
 182
 183         tcon = __raw_readl(S3C2410_TCON);
 184         tcon |= pwm_tcon_manulupdate(s3c);
 185         tcon |= pwm_tcon_autoreload(s3c);
 186         __raw_writel(tcon, S3C2410_TCON);
 187
 188         tcon &= ~pwm_tcon_manulupdate(s3c);
 189         __raw_writel(tcon, S3C2410_TCON);
 190
 191         local_irq_restore(flags);
 192
 193         return 0;
 194 }
 195
 196 static struct pwm_ops s3c_pwm_ops = {
 197         .enable = s3c_pwm_enable,
 198         .disable = s3c_pwm_disable,
 199         .config = s3c_pwm_config,
 200         .owner = THIS_MODULE,
 201 };
 202
 203 static int s3c_pwm_probe(struct platform_device *pdev)
 204 {
 205         struct device *dev = &pdev->dev;
 206         struct s3c_chip *s3c;
 207         unsigned long flags;
 208         unsigned long tcon;
 209         unsigned int id = pdev->id;
 210         int ret;
 211
 212         if (id == 4) {
 213                 dev_err(dev, "TIMER4 is currently not supported\n");
 214                 return -ENXIO;
 215         }
 216
 217         s3c = devm_kzalloc(&pdev->dev, sizeof(*s3c), GFP_KERNEL);
 218         if (s3c == NULL) {
 219                 dev_err(dev, "failed to allocate pwm_device\n");
 220                 return -ENOMEM;
 221         }
 222
 223         /* calculate base of control bits in TCON */
 224         s3c->tcon_base = id == 0 ? 0 : (id * 4) + 4;
 225         s3c->pwm_id = id;
 226         s3c->chip.dev = &pdev->dev;
 227         s3c->chip.ops = &s3c_pwm_ops;
 228         s3c->chip.base = -1;
 229         s3c->chip.npwm = 1;
 230
 231         s3c->clk = devm_clk_get(dev, "pwm-tin");
 232         if (IS_ERR(s3c->clk)) {
 233                 dev_err(dev, "failed to get pwm tin clk\n");
 234                 return PTR_ERR(s3c->clk);
 235         }
 236
 237         s3c->clk_div = devm_clk_get(dev, "pwm-tdiv");
 238         if (IS_ERR(s3c->clk_div)) {
 239                 dev_err(dev, "failed to get pwm tdiv clk\n");
 240                 return PTR_ERR(s3c->clk_div);
 241         }
 242
 243         clk_enable(s3c->clk);
 244         clk_enable(s3c->clk_div);
 245
 246         local_irq_save(flags);
 247
 248         tcon = __raw_readl(S3C2410_TCON);
 249         tcon |= pwm_tcon_invert(s3c);
 250         __raw_writel(tcon, S3C2410_TCON);
 251
 252         local_irq_restore(flags);
 253
 254         ret = pwmchip_add(&s3c->chip);
 255         if (ret < 0) {
 256                 dev_err(dev, "failed to register pwm\n");
 257                 goto err_clk_tdiv;
 258         }
 259
 260         pwm_dbg(s3c, "config bits %02x\n",
 261                 (__raw_readl(S3C2410_TCON) >> s3c->tcon_base) & 0x0f);
 262
 263         dev_info(dev, "tin at %lu, tdiv at %lu, tin=%sclk, base %d\n",
 264                  clk_get_rate(s3c->clk),
 265                  clk_get_rate(s3c->clk_div),
 266                  pwm_is_tdiv(s3c) ? "div" : "ext", s3c->tcon_base);
 267
 268         platform_set_drvdata(pdev, s3c);
 269         return 0;
 270
 271  err_clk_tdiv:
 272         clk_disable(s3c->clk_div);
 273         clk_disable(s3c->clk);
 274         return ret;
 275 }
 276
 277 static int s3c_pwm_remove(struct platform_device *pdev)
 278 {
 279         struct s3c_chip *s3c = platform_get_drvdata(pdev);
 280         int err;
 281
 282         err = pwmchip_remove(&s3c->chip);
 283         if (err < 0)
 284                 return err;
 285
 286         clk_disable(s3c->clk_div);
 287         clk_disable(s3c->clk);
 288
 289         return 0;
 290 }
 291
 292 #ifdef CONFIG_PM
 293 static int s3c_pwm_suspend(struct platform_device *pdev, pm_message_t state)
 294 {
 295         struct s3c_chip *s3c = platform_get_drvdata(pdev);
 296
 297         /* No one preserve these values during suspend so reset them
 298          * Otherwise driver leaves PWM unconfigured if same values
 299          * passed to pwm_config
 300          */
 301         s3c->period_ns = 0;
 302         s3c->duty_ns = 0;
 303
 304         return 0;
 305 }
 306
 307 static int s3c_pwm_resume(struct platform_device *pdev)
 308 {
 309         struct s3c_chip *s3c = platform_get_drvdata(pdev);
 310         unsigned long tcon;
 311
 312         /* Restore invertion */
 313         tcon = __raw_readl(S3C2410_TCON);
 314         tcon |= pwm_tcon_invert(s3c);
 315         __raw_writel(tcon, S3C2410_TCON);
 316
 317         return 0;
 318 }
 319
 320 #else
 321 #define s3c_pwm_suspend NULL
 322 #define s3c_pwm_resume NULL
 323 #endif
 324
 325 static struct platform_driver s3c_pwm_driver = {
 326         .driver         = {
 327                 .name   = "s3c24xx-pwm",
 328                 .owner  = THIS_MODULE,
 329         },
 330         .probe          = s3c_pwm_probe,
 331         .remove         = s3c_pwm_remove,
 332         .suspend        = s3c_pwm_suspend,
 333         .resume         = s3c_pwm_resume,
 334 };
 335
 336 static int __init pwm_init(void)
 337 {
 338         int ret;
 339
 340         clk_scaler[0] = clk_get(NULL, "pwm-scaler0");
 341         clk_scaler[1] = clk_get(NULL, "pwm-scaler1");
 342
 343         if (IS_ERR(clk_scaler[0]) || IS_ERR(clk_scaler[1])) {
 344                 pr_err("failed to get scaler clocks\n");
 345                 return -EINVAL;
 346         }
 347
 348         ret = platform_driver_register(&s3c_pwm_driver);
 349         if (ret)
 350                 pr_err("failed to add pwm driver\n");
 351
 352         return ret;
 353 }
 354
 355 arch_initcall(pwm_init);