drivers/pwm/pwm-atmel-hlcdc.c

   1 /*
   2  * Copyright (C) 2014 Free Electrons
   3  * Copyright (C) 2014 Atmel
   4  *
   5  * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License version 2 as published by
   9  * the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  14  * more details.
  15  *
  16  * You should have received a copy of the GNU General Public License along with
  17  * this program.  If not, see <http://www.gnu.org/licenses/>.
  18  */
  19
  20 #include <linux/clk.h>
  21 #include <linux/delay.h>
  22 #include <linux/mfd/atmel-hlcdc.h>
  23 #include <linux/module.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/pwm.h>
  26 #include <linux/regmap.h>
  27
  28 #define ATMEL_HLCDC_PWMCVAL_MASK        GENMASK(15, 8)
  29 #define ATMEL_HLCDC_PWMCVAL(x)          (((x) << 8) & ATMEL_HLCDC_PWMCVAL_MASK)
  30 #define ATMEL_HLCDC_PWMPOL              BIT(4)
  31 #define ATMEL_HLCDC_PWMPS_MASK          GENMASK(2, 0)
  32 #define ATMEL_HLCDC_PWMPS_MAX           0x6
  33 #define ATMEL_HLCDC_PWMPS(x)            ((x) & ATMEL_HLCDC_PWMPS_MASK)
  34
  35 struct atmel_hlcdc_pwm_errata {
  36         bool slow_clk_erratum;
  37         bool div1_clk_erratum;
  38 };
  39
  40 struct atmel_hlcdc_pwm {
  41         struct pwm_chip chip;
  42         struct atmel_hlcdc *hlcdc;
  43         struct clk *cur_clk;
  44         const struct atmel_hlcdc_pwm_errata *errata;
  45 };
  46
  47 static inline struct atmel_hlcdc_pwm *to_atmel_hlcdc_pwm(struct pwm_chip *chip)
  48 {
  49         return container_of(chip, struct atmel_hlcdc_pwm, chip);
  50 }
  51
  52 static int atmel_hlcdc_pwm_config(struct pwm_chip *c,
  53                                   struct pwm_device *pwm,
  54                                   int duty_ns, int period_ns)
  55 {
  56         struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
  57         struct atmel_hlcdc *hlcdc = chip->hlcdc;
  58         struct clk *new_clk = hlcdc->slow_clk;
  59         u64 pwmcval = duty_ns * 256;
  60         unsigned long clk_freq;
  61         u64 clk_period_ns;
  62         u32 pwmcfg;
  63         int pres;
  64
  65         if (!chip->errata || !chip->errata->slow_clk_erratum) {
  66                 clk_freq = clk_get_rate(new_clk);
  67                 clk_period_ns = (u64)NSEC_PER_SEC * 256;
  68                 do_div(clk_period_ns, clk_freq);
  69         }
  70
  71         /* Errata: cannot use slow clk on some IP revisions */
  72         if ((chip->errata && chip->errata->slow_clk_erratum) ||
  73             clk_period_ns > period_ns) {
  74                 new_clk = hlcdc->sys_clk;
  75                 clk_freq = clk_get_rate(new_clk);
  76                 clk_period_ns = (u64)NSEC_PER_SEC * 256;
  77                 do_div(clk_period_ns, clk_freq);
  78         }
  79
  80         for (pres = 0; pres <= ATMEL_HLCDC_PWMPS_MAX; pres++) {
  81                 /* Errata: cannot divide by 1 on some IP revisions */
  82                 if (!pres && chip->errata && chip->errata->div1_clk_erratum)
  83                         continue;
  84
  85                 if ((clk_period_ns << pres) >= period_ns)
  86                         break;
  87         }
  88
  89         if (pres > ATMEL_HLCDC_PWMPS_MAX)
  90                 return -EINVAL;
  91
  92         pwmcfg = ATMEL_HLCDC_PWMPS(pres);
  93
  94         if (new_clk != chip->cur_clk) {
  95                 u32 gencfg = 0;
  96                 int ret;
  97
  98                 ret = clk_prepare_enable(new_clk);
  99                 if (ret)
 100                         return ret;
 101
 102                 clk_disable_unprepare(chip->cur_clk);
 103                 chip->cur_clk = new_clk;
 104
 105                 if (new_clk == hlcdc->sys_clk)
 106                         gencfg = ATMEL_HLCDC_CLKPWMSEL;
 107
 108                 ret = regmap_update_bits(hlcdc->regmap, ATMEL_HLCDC_CFG(0),
 109                                          ATMEL_HLCDC_CLKPWMSEL, gencfg);
 110                 if (ret)
 111                         return ret;
 112         }
 113
 114         do_div(pwmcval, period_ns);
 115
 116         /*
 117          * The PWM duty cycle is configurable from 0/256 to 255/256 of the
 118          * period cycle. Hence we can't set a duty cycle occupying the
 119          * whole period cycle if we're asked to.
 120          * Set it to 255 if pwmcval is greater than 256.
 121          */
 122         if (pwmcval > 255)
 123                 pwmcval = 255;
 124
 125         pwmcfg |= ATMEL_HLCDC_PWMCVAL(pwmcval);
 126
 127         return regmap_update_bits(hlcdc->regmap, ATMEL_HLCDC_CFG(6),
 128                                   ATMEL_HLCDC_PWMCVAL_MASK |
 129                                   ATMEL_HLCDC_PWMPS_MASK,
 130                                   pwmcfg);
 131 }
 132
 133 static int atmel_hlcdc_pwm_set_polarity(struct pwm_chip *c,
 134                                         struct pwm_device *pwm,
 135                                         enum pwm_polarity polarity)
 136 {
 137         struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
 138         struct atmel_hlcdc *hlcdc = chip->hlcdc;
 139         u32 cfg = 0;
 140
 141         if (polarity == PWM_POLARITY_NORMAL)
 142                 cfg = ATMEL_HLCDC_PWMPOL;
 143
 144         return regmap_update_bits(hlcdc->regmap, ATMEL_HLCDC_CFG(6),
 145                                   ATMEL_HLCDC_PWMPOL, cfg);
 146 }
 147
 148 static int atmel_hlcdc_pwm_enable(struct pwm_chip *c, struct pwm_device *pwm)
 149 {
 150         struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
 151         struct atmel_hlcdc *hlcdc = chip->hlcdc;
 152         u32 status;
 153         int ret;
 154
 155         ret = regmap_write(hlcdc->regmap, ATMEL_HLCDC_EN, ATMEL_HLCDC_PWM);
 156         if (ret)
 157                 return ret;
 158
 159         while (true) {
 160                 ret = regmap_read(hlcdc->regmap, ATMEL_HLCDC_SR, &status);
 161                 if (ret)
 162                         return ret;
 163
 164                 if ((status & ATMEL_HLCDC_PWM) != 0)
 165                         break;
 166
 167                 usleep_range(1, 10);
 168         }
 169
 170         return 0;
 171 }
 172
 173 static void atmel_hlcdc_pwm_disable(struct pwm_chip *c,
 174                                     struct pwm_device *pwm)
 175 {
 176         struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
 177         struct atmel_hlcdc *hlcdc = chip->hlcdc;
 178         u32 status;
 179         int ret;
 180
 181         ret = regmap_write(hlcdc->regmap, ATMEL_HLCDC_DIS, ATMEL_HLCDC_PWM);
 182         if (ret)
 183                 return;
 184
 185         while (true) {
 186                 ret = regmap_read(hlcdc->regmap, ATMEL_HLCDC_SR, &status);
 187                 if (ret)
 188                         return;
 189
 190                 if ((status & ATMEL_HLCDC_PWM) == 0)
 191                         break;
 192
 193                 usleep_range(1, 10);
 194         }
 195 }
 196
 197 static const struct pwm_ops atmel_hlcdc_pwm_ops = {
 198         .config = atmel_hlcdc_pwm_config,
 199         .set_polarity = atmel_hlcdc_pwm_set_polarity,
 200         .enable = atmel_hlcdc_pwm_enable,
 201         .disable = atmel_hlcdc_pwm_disable,
 202         .owner = THIS_MODULE,
 203 };
 204
 205 static const struct atmel_hlcdc_pwm_errata atmel_hlcdc_pwm_at91sam9x5_errata = {
 206         .slow_clk_erratum = true,
 207 };
 208
 209 static const struct atmel_hlcdc_pwm_errata atmel_hlcdc_pwm_sama5d3_errata = {
 210         .div1_clk_erratum = true,
 211 };
 212
 213 static const struct of_device_id atmel_hlcdc_dt_ids[] = {
 214         {
 215                 .compatible = "atmel,at91sam9x5-hlcdc",
 216                 .data = &atmel_hlcdc_pwm_at91sam9x5_errata,
 217         },
 218         {
 219                 .compatible = "atmel,sama5d3-hlcdc",
 220                 .data = &atmel_hlcdc_pwm_sama5d3_errata,
 221         },
 222         { /* sentinel */ },
 223 };
 224
 225 static int atmel_hlcdc_pwm_probe(struct platform_device *pdev)
 226 {
 227         const struct of_device_id *match;
 228         struct device *dev = &pdev->dev;
 229         struct atmel_hlcdc_pwm *chip;
 230         struct atmel_hlcdc *hlcdc;
 231         int ret;
 232
 233         hlcdc = dev_get_drvdata(dev->parent);
 234
 235         chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
 236         if (!chip)
 237                 return -ENOMEM;
 238
 239         ret = clk_prepare_enable(hlcdc->periph_clk);
 240         if (ret)
 241                 return ret;
 242
 243         match = of_match_node(atmel_hlcdc_dt_ids, dev->parent->of_node);
 244         if (match)
 245                 chip->errata = match->data;
 246
 247         chip->hlcdc = hlcdc;
 248         chip->chip.ops = &atmel_hlcdc_pwm_ops;
 249         chip->chip.dev = dev;
 250         chip->chip.base = -1;
 251         chip->chip.npwm = 1;
 252         chip->chip.of_xlate = of_pwm_xlate_with_flags;
 253         chip->chip.of_pwm_n_cells = 3;
 254         chip->chip.can_sleep = 1;
 255
 256         ret = pwmchip_add(&chip->chip);
 257         if (ret) {
 258                 clk_disable_unprepare(hlcdc->periph_clk);
 259                 return ret;
 260         }
 261
 262         platform_set_drvdata(pdev, chip);
 263
 264         return 0;
 265 }
 266
 267 static int atmel_hlcdc_pwm_remove(struct platform_device *pdev)
 268 {
 269         struct atmel_hlcdc_pwm *chip = platform_get_drvdata(pdev);
 270         int ret;
 271
 272         ret = pwmchip_remove(&chip->chip);
 273         if (ret)
 274                 return ret;
 275
 276         clk_disable_unprepare(chip->hlcdc->periph_clk);
 277
 278         return 0;
 279 }
 280
 281 static const struct of_device_id atmel_hlcdc_pwm_dt_ids[] = {
 282         { .compatible = "atmel,hlcdc-pwm" },
 283         { /* sentinel */ },
 284 };
 285
 286 static struct platform_driver atmel_hlcdc_pwm_driver = {
 287         .driver = {
 288                 .name = "atmel-hlcdc-pwm",
 289                 .of_match_table = atmel_hlcdc_pwm_dt_ids,
 290         },
 291         .probe = atmel_hlcdc_pwm_probe,
 292         .remove = atmel_hlcdc_pwm_remove,
 293 };
 294 module_platform_driver(atmel_hlcdc_pwm_driver);
 295
 296 MODULE_ALIAS("platform:atmel-hlcdc-pwm");
 297 MODULE_AUTHOR("Boris Brezillon <boris.brezillon@free-electrons.com>");
 298 MODULE_DESCRIPTION("Atmel HLCDC PWM driver");
 299 MODULE_LICENSE("GPL v2");