drivers/pwm/pwm-sti.c

   1 /*
   2  * PWM device driver for ST SoCs.
   3  * Author: Ajit Pal Singh <ajitpal.singh@st.com>
   4  *
   5  * Copyright (C) 2013-2014 STMicroelectronics (R&D) Limited
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  */
  12
  13 #include <linux/clk.h>
  14 #include <linux/math64.h>
  15 #include <linux/mfd/syscon.h>
  16 #include <linux/module.h>
  17 #include <linux/of.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/pwm.h>
  20 #include <linux/regmap.h>
  21 #include <linux/slab.h>
  22 #include <linux/time.h>
  23
  24 #define STI_DS_REG(ch)  (4 * (ch))      /* Channel's Duty Cycle register */
  25 #define STI_PWMCR       0x50            /* Control/Config register */
  26 #define STI_INTEN       0x54            /* Interrupt Enable/Disable register */
  27 #define PWM_PRESCALE_LOW_MASK           0x0f
  28 #define PWM_PRESCALE_HIGH_MASK          0xf0
  29
  30 /* Regfield IDs */
  31 enum {
  32         PWMCLK_PRESCALE_LOW,
  33         PWMCLK_PRESCALE_HIGH,
  34         PWM_EN,
  35         PWM_INT_EN,
  36
  37         /* Keep last */
  38         MAX_REGFIELDS
  39 };
  40
  41 struct sti_pwm_compat_data {
  42         const struct reg_field *reg_fields;
  43         unsigned int num_chan;
  44         unsigned int max_pwm_cnt;
  45         unsigned int max_prescale;
  46 };
  47
  48 struct sti_pwm_chip {
  49         struct device *dev;
  50         struct clk *clk;
  51         unsigned long clk_rate;
  52         struct regmap *regmap;
  53         struct sti_pwm_compat_data *cdata;
  54         struct regmap_field *prescale_low;
  55         struct regmap_field *prescale_high;
  56         struct regmap_field *pwm_en;
  57         struct regmap_field *pwm_int_en;
  58         struct pwm_chip chip;
  59         struct pwm_device *cur;
  60         unsigned long configured;
  61         unsigned int en_count;
  62         struct mutex sti_pwm_lock; /* To sync between enable/disable calls */
  63         void __iomem *mmio;
  64 };
  65
  66 static const struct reg_field sti_pwm_regfields[MAX_REGFIELDS] = {
  67         [PWMCLK_PRESCALE_LOW]   = REG_FIELD(STI_PWMCR, 0, 3),
  68         [PWMCLK_PRESCALE_HIGH]  = REG_FIELD(STI_PWMCR, 11, 14),
  69         [PWM_EN]                = REG_FIELD(STI_PWMCR, 9, 9),
  70         [PWM_INT_EN]            = REG_FIELD(STI_INTEN, 0, 0),
  71 };
  72
  73 static inline struct sti_pwm_chip *to_sti_pwmchip(struct pwm_chip *chip)
  74 {
  75         return container_of(chip, struct sti_pwm_chip, chip);
  76 }
  77
  78 /*
  79  * Calculate the prescaler value corresponding to the period.
  80  */
  81 static int sti_pwm_get_prescale(struct sti_pwm_chip *pc, unsigned long period,
  82                                 unsigned int *prescale)
  83 {
  84         struct sti_pwm_compat_data *cdata = pc->cdata;
  85         unsigned long val;
  86         unsigned int ps;
  87
  88         /*
  89          * prescale = ((period_ns * clk_rate) / (10^9 * (max_pwm_count + 1)) - 1
  90          */
  91         val = NSEC_PER_SEC / pc->clk_rate;
  92         val *= cdata->max_pwm_cnt + 1;
  93
  94         if (period % val) {
  95                 return -EINVAL;
  96         } else {
  97                 ps  = period / val - 1;
  98                 if (ps > cdata->max_prescale)
  99                         return -EINVAL;
 100         }
 101         *prescale = ps;
 102
 103         return 0;
 104 }
 105
 106 /*
 107  * For STiH4xx PWM IP, the PWM period is fixed to 256 local clock cycles.
 108  * The only way to change the period (apart from changing the PWM input clock)
 109  * is to change the PWM clock prescaler.
 110  * The prescaler is of 8 bits, so 256 prescaler values and hence
 111  * 256 possible period values are supported (for a particular clock rate).
 112  * The requested period will be applied only if it matches one of these
 113  * 256 values.
 114  */
 115 static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 116                          int duty_ns, int period_ns)
 117 {
 118         struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
 119         struct sti_pwm_compat_data *cdata = pc->cdata;
 120         struct pwm_device *cur = pc->cur;
 121         struct device *dev = pc->dev;
 122         unsigned int prescale = 0, pwmvalx;
 123         int ret;
 124         unsigned int ncfg;
 125         bool period_same = false;
 126
 127         ncfg = hweight_long(pc->configured);
 128         if (ncfg)
 129                 period_same = (period_ns == pwm_get_period(cur));
 130
 131         /* Allow configuration changes if one of the
 132          * following conditions satisfy.
 133          * 1. No channels have been configured.
 134          * 2. Only one channel has been configured and the new request
 135          *    is for the same channel.
 136          * 3. Only one channel has been configured and the new request is
 137          *    for a new channel and period of the new channel is same as
 138          *    the current configured period.
 139          * 4. More than one channels are configured and period of the new
 140          *    requestis the same as the current period.
 141          */
 142         if (!ncfg ||
 143             ((ncfg == 1) && (pwm->hwpwm == cur->hwpwm)) ||
 144             ((ncfg == 1) && (pwm->hwpwm != cur->hwpwm) && period_same) ||
 145             ((ncfg > 1) && period_same)) {
 146                 /* Enable clock before writing to PWM registers. */
 147                 ret = clk_enable(pc->clk);
 148                 if (ret)
 149                         return ret;
 150
 151                 if (!period_same) {
 152                         ret = sti_pwm_get_prescale(pc, period_ns, &prescale);
 153                         if (ret)
 154                                 goto clk_dis;
 155
 156                         ret =
 157                         regmap_field_write(pc->prescale_low,
 158                                            prescale & PWM_PRESCALE_LOW_MASK);
 159                         if (ret)
 160                                 goto clk_dis;
 161
 162                         ret =
 163                         regmap_field_write(pc->prescale_high,
 164                                 (prescale & PWM_PRESCALE_HIGH_MASK) >> 4);
 165                         if (ret)
 166                                 goto clk_dis;
 167                 }
 168
 169                 /*
 170                  * When PWMVal == 0, PWM pulse = 1 local clock cycle.
 171                  * When PWMVal == max_pwm_count,
 172                  * PWM pulse = (max_pwm_count + 1) local cycles,
 173                  * that is continuous pulse: signal never goes low.
 174                  */
 175                 pwmvalx = cdata->max_pwm_cnt * duty_ns / period_ns;
 176
 177                 ret = regmap_write(pc->regmap, STI_DS_REG(pwm->hwpwm), pwmvalx);
 178                 if (ret)
 179                         goto clk_dis;
 180
 181                 ret = regmap_field_write(pc->pwm_int_en, 0);
 182
 183                 set_bit(pwm->hwpwm, &pc->configured);
 184                 pc->cur = pwm;
 185
 186                 dev_dbg(dev, "prescale:%u, period:%i, duty:%i, pwmvalx:%u\n",
 187                         prescale, period_ns, duty_ns, pwmvalx);
 188         } else {
 189                 return -EINVAL;
 190         }
 191
 192 clk_dis:
 193         clk_disable(pc->clk);
 194         return ret;
 195 }
 196
 197 static int sti_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 198 {
 199         struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
 200         struct device *dev = pc->dev;
 201         int ret = 0;
 202
 203         /*
 204          * Since we have a common enable for all PWM channels,
 205          * do not enable if already enabled.
 206          */
 207         mutex_lock(&pc->sti_pwm_lock);
 208         if (!pc->en_count) {
 209                 ret = clk_enable(pc->clk);
 210                 if (ret)
 211                         goto out;
 212
 213                 ret = regmap_field_write(pc->pwm_en, 1);
 214                 if (ret) {
 215                         dev_err(dev, "failed to enable PWM device:%d\n",
 216                                 pwm->hwpwm);
 217                         goto out;
 218                 }
 219         }
 220         pc->en_count++;
 221 out:
 222         mutex_unlock(&pc->sti_pwm_lock);
 223         return ret;
 224 }
 225
 226 static void sti_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 227 {
 228         struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
 229
 230         mutex_lock(&pc->sti_pwm_lock);
 231         if (--pc->en_count) {
 232                 mutex_unlock(&pc->sti_pwm_lock);
 233                 return;
 234         }
 235         regmap_field_write(pc->pwm_en, 0);
 236
 237         clk_disable(pc->clk);
 238         mutex_unlock(&pc->sti_pwm_lock);
 239 }
 240
 241 static void sti_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 242 {
 243         struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
 244
 245         clear_bit(pwm->hwpwm, &pc->configured);
 246 }
 247
 248 static const struct pwm_ops sti_pwm_ops = {
 249         .config = sti_pwm_config,
 250         .enable = sti_pwm_enable,
 251         .disable = sti_pwm_disable,
 252         .free = sti_pwm_free,
 253         .owner = THIS_MODULE,
 254 };
 255
 256 static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
 257 {
 258         struct device *dev = pc->dev;
 259         const struct reg_field *reg_fields;
 260         struct device_node *np = dev->of_node;
 261         struct sti_pwm_compat_data *cdata = pc->cdata;
 262         u32 num_chan;
 263
 264         of_property_read_u32(np, "st,pwm-num-chan", &num_chan);
 265         if (num_chan)
 266                 cdata->num_chan = num_chan;
 267
 268         reg_fields = cdata->reg_fields;
 269
 270         pc->prescale_low = devm_regmap_field_alloc(dev, pc->regmap,
 271                                         reg_fields[PWMCLK_PRESCALE_LOW]);
 272         if (IS_ERR(pc->prescale_low))
 273                 return PTR_ERR(pc->prescale_low);
 274
 275         pc->prescale_high = devm_regmap_field_alloc(dev, pc->regmap,
 276                                         reg_fields[PWMCLK_PRESCALE_HIGH]);
 277         if (IS_ERR(pc->prescale_high))
 278                 return PTR_ERR(pc->prescale_high);
 279
 280         pc->pwm_en = devm_regmap_field_alloc(dev, pc->regmap,
 281                                              reg_fields[PWM_EN]);
 282         if (IS_ERR(pc->pwm_en))
 283                 return PTR_ERR(pc->pwm_en);
 284
 285         pc->pwm_int_en = devm_regmap_field_alloc(dev, pc->regmap,
 286                                                  reg_fields[PWM_INT_EN]);
 287         if (IS_ERR(pc->pwm_int_en))
 288                 return PTR_ERR(pc->pwm_int_en);
 289
 290         return 0;
 291 }
 292
 293 static const struct regmap_config sti_pwm_regmap_config = {
 294         .reg_bits = 32,
 295         .val_bits = 32,
 296         .reg_stride = 4,
 297 };
 298
 299 static int sti_pwm_probe(struct platform_device *pdev)
 300 {
 301         struct device *dev = &pdev->dev;
 302         struct sti_pwm_compat_data *cdata;
 303         struct sti_pwm_chip *pc;
 304         struct resource *res;
 305         int ret;
 306
 307         pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL);
 308         if (!pc)
 309                 return -ENOMEM;
 310
 311         cdata = devm_kzalloc(dev, sizeof(*cdata), GFP_KERNEL);
 312         if (!cdata)
 313                 return -ENOMEM;
 314
 315         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 316
 317         pc->mmio = devm_ioremap_resource(dev, res);
 318         if (IS_ERR(pc->mmio))
 319                 return PTR_ERR(pc->mmio);
 320
 321         pc->regmap = devm_regmap_init_mmio(dev, pc->mmio,
 322                                            &sti_pwm_regmap_config);
 323         if (IS_ERR(pc->regmap))
 324                 return PTR_ERR(pc->regmap);
 325
 326         /*
 327          * Setup PWM data with default values: some values could be replaced
 328          * with specific ones provided from Device Tree.
 329          */
 330         cdata->reg_fields   = &sti_pwm_regfields[0];
 331         cdata->max_prescale = 0xff;
 332         cdata->max_pwm_cnt  = 255;
 333         cdata->num_chan     = 1;
 334
 335         pc->cdata = cdata;
 336         pc->dev = dev;
 337         pc->en_count = 0;
 338         mutex_init(&pc->sti_pwm_lock);
 339
 340         ret = sti_pwm_probe_dt(pc);
 341         if (ret)
 342                 return ret;
 343
 344         pc->clk = of_clk_get_by_name(dev->of_node, "pwm");
 345         if (IS_ERR(pc->clk)) {
 346                 dev_err(dev, "failed to get PWM clock\n");
 347                 return PTR_ERR(pc->clk);
 348         }
 349
 350         pc->clk_rate = clk_get_rate(pc->clk);
 351         if (!pc->clk_rate) {
 352                 dev_err(dev, "failed to get clock rate\n");
 353                 return -EINVAL;
 354         }
 355
 356         ret = clk_prepare(pc->clk);
 357         if (ret) {
 358                 dev_err(dev, "failed to prepare clock\n");
 359                 return ret;
 360         }
 361
 362         pc->chip.dev = dev;
 363         pc->chip.ops = &sti_pwm_ops;
 364         pc->chip.base = -1;
 365         pc->chip.npwm = pc->cdata->num_chan;
 366         pc->chip.can_sleep = true;
 367
 368         ret = pwmchip_add(&pc->chip);
 369         if (ret < 0) {
 370                 clk_unprepare(pc->clk);
 371                 return ret;
 372         }
 373
 374         platform_set_drvdata(pdev, pc);
 375
 376         return 0;
 377 }
 378
 379 static int sti_pwm_remove(struct platform_device *pdev)
 380 {
 381         struct sti_pwm_chip *pc = platform_get_drvdata(pdev);
 382         unsigned int i;
 383
 384         for (i = 0; i < pc->cdata->num_chan; i++)
 385                 pwm_disable(&pc->chip.pwms[i]);
 386
 387         clk_unprepare(pc->clk);
 388
 389         return pwmchip_remove(&pc->chip);
 390 }
 391
 392 static const struct of_device_id sti_pwm_of_match[] = {
 393         { .compatible = "st,sti-pwm", },
 394         { /* sentinel */ }
 395 };
 396 MODULE_DEVICE_TABLE(of, sti_pwm_of_match);
 397
 398 static struct platform_driver sti_pwm_driver = {
 399         .driver = {
 400                 .name = "sti-pwm",
 401                 .of_match_table = sti_pwm_of_match,
 402         },
 403         .probe = sti_pwm_probe,
 404         .remove = sti_pwm_remove,
 405 };
 406 module_platform_driver(sti_pwm_driver);
 407
 408 MODULE_AUTHOR("Ajit Pal Singh <ajitpal.singh@st.com>");
 409 MODULE_DESCRIPTION("STMicroelectronics ST PWM driver");
 410 MODULE_LICENSE("GPL");