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                 if (!clk_freq)
  68                         return -EINVAL;
  69
  70                 clk_period_ns = (u64)NSEC_PER_SEC * 256;
  71                 do_div(clk_period_ns, clk_freq);
  72         }
  73
  74         /* Errata: cannot use slow clk on some IP revisions */
  75         if ((chip->errata && chip->errata->slow_clk_erratum) ||
  76             clk_period_ns > period_ns) {
  77                 new_clk = hlcdc->sys_clk;
  78                 clk_freq = clk_get_rate(new_clk);
  79                 if (!clk_freq)
  80                         return -EINVAL;
  81
  82                 clk_period_ns = (u64)NSEC_PER_SEC * 256;
  83                 do_div(clk_period_ns, clk_freq);
  84         }
  85
  86         for (pres = 0; pres <= ATMEL_HLCDC_PWMPS_MAX; pres++) {
  87                 /* Errata: cannot divide by 1 on some IP revisions */
  88                 if (!pres && chip->errata && chip->errata->div1_clk_erratum)
  89                         continue;
  90
  91                 if ((clk_period_ns << pres) >= period_ns)
  92                         break;
  93         }
  94
  95         if (pres > ATMEL_HLCDC_PWMPS_MAX)
  96                 return -EINVAL;
  97
  98         pwmcfg = ATMEL_HLCDC_PWMPS(pres);
  99
 100         if (new_clk != chip->cur_clk) {
 101                 u32 gencfg = 0;
 102                 int ret;
 103
 104                 ret = clk_prepare_enable(new_clk);
 105                 if (ret)
 106                         return ret;
 107
 108                 clk_disable_unprepare(chip->cur_clk);
 109                 chip->cur_clk = new_clk;
 110
 111                 if (new_clk == hlcdc->sys_clk)
 112                         gencfg = ATMEL_HLCDC_CLKPWMSEL;
 113
 114                 ret = regmap_update_bits(hlcdc->regmap, ATMEL_HLCDC_CFG(0),
 115                                          ATMEL_HLCDC_CLKPWMSEL, gencfg);
 116                 if (ret)
 117                         return ret;
 118         }
 119
 120         do_div(pwmcval, period_ns);
 121
 122         /*
 123          * The PWM duty cycle is configurable from 0/256 to 255/256 of the
 124          * period cycle. Hence we can't set a duty cycle occupying the
 125          * whole period cycle if we're asked to.
 126          * Set it to 255 if pwmcval is greater than 256.
 127          */
 128         if (pwmcval > 255)
 129                 pwmcval = 255;
 130
 131         pwmcfg |= ATMEL_HLCDC_PWMCVAL(pwmcval);
 132
 133         return regmap_update_bits(hlcdc->regmap, ATMEL_HLCDC_CFG(6),
 134                                   ATMEL_HLCDC_PWMCVAL_MASK |
 135                                   ATMEL_HLCDC_PWMPS_MASK,
 136                                   pwmcfg);
 137 }
 138
 139 static int atmel_hlcdc_pwm_set_polarity(struct pwm_chip *c,
 140                                         struct pwm_device *pwm,
 141                                         enum pwm_polarity polarity)
 142 {
 143         struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
 144         struct atmel_hlcdc *hlcdc = chip->hlcdc;
 145         u32 cfg = 0;
 146
 147         if (polarity == PWM_POLARITY_NORMAL)
 148                 cfg = ATMEL_HLCDC_PWMPOL;
 149
 150         return regmap_update_bits(hlcdc->regmap, ATMEL_HLCDC_CFG(6),
 151                                   ATMEL_HLCDC_PWMPOL, cfg);
 152 }
 153
 154 static int atmel_hlcdc_pwm_enable(struct pwm_chip *c, struct pwm_device *pwm)
 155 {
 156         struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
 157         struct atmel_hlcdc *hlcdc = chip->hlcdc;
 158         u32 status;
 159         int ret;
 160
 161         ret = regmap_write(hlcdc->regmap, ATMEL_HLCDC_EN, ATMEL_HLCDC_PWM);
 162         if (ret)
 163                 return ret;
 164
 165         while (true) {
 166                 ret = regmap_read(hlcdc->regmap, ATMEL_HLCDC_SR, &status);
 167                 if (ret)
 168                         return ret;
 169
 170                 if ((status & ATMEL_HLCDC_PWM) != 0)
 171                         break;
 172
 173                 usleep_range(1, 10);
 174         }
 175
 176         return 0;
 177 }
 178
 179 static void atmel_hlcdc_pwm_disable(struct pwm_chip *c,
 180                                     struct pwm_device *pwm)
 181 {
 182         struct atmel_hlcdc_pwm *chip = to_atmel_hlcdc_pwm(c);
 183         struct atmel_hlcdc *hlcdc = chip->hlcdc;
 184         u32 status;
 185         int ret;
 186
 187         ret = regmap_write(hlcdc->regmap, ATMEL_HLCDC_DIS, ATMEL_HLCDC_PWM);
 188         if (ret)
 189                 return;
 190
 191         while (true) {
 192                 ret = regmap_read(hlcdc->regmap, ATMEL_HLCDC_SR, &status);
 193                 if (ret)
 194                         return;
 195
 196                 if ((status & ATMEL_HLCDC_PWM) == 0)
 197                         break;
 198
 199                 usleep_range(1, 10);
 200         }
 201 }
 202
 203 static const struct pwm_ops atmel_hlcdc_pwm_ops = {
 204         .config = atmel_hlcdc_pwm_config,
 205         .set_polarity = atmel_hlcdc_pwm_set_polarity,
 206         .enable = atmel_hlcdc_pwm_enable,
 207         .disable = atmel_hlcdc_pwm_disable,
 208         .owner = THIS_MODULE,
 209 };
 210
 211 static const struct atmel_hlcdc_pwm_errata atmel_hlcdc_pwm_at91sam9x5_errata = {
 212         .slow_clk_erratum = true,
 213 };
 214
 215 static const struct atmel_hlcdc_pwm_errata atmel_hlcdc_pwm_sama5d3_errata = {
 216         .div1_clk_erratum = true,
 217 };
 218
 219 static const struct of_device_id atmel_hlcdc_dt_ids[] = {
 220         {
 221                 .compatible = "atmel,at91sam9x5-hlcdc",
 222                 .data = &atmel_hlcdc_pwm_at91sam9x5_errata,
 223         },
 224         {
 225                 .compatible = "atmel,sama5d3-hlcdc",
 226                 .data = &atmel_hlcdc_pwm_sama5d3_errata,
 227         },
 228         {
 229                 .compatible = "atmel,sama5d4-hlcdc",
 230                 .data = &atmel_hlcdc_pwm_sama5d3_errata,
 231         },
 232         { /* sentinel */ },
 233 };
 234
 235 static int atmel_hlcdc_pwm_probe(struct platform_device *pdev)
 236 {
 237         const struct of_device_id *match;
 238         struct device *dev = &pdev->dev;
 239         struct atmel_hlcdc_pwm *chip;
 240         struct atmel_hlcdc *hlcdc;
 241         int ret;
 242
 243         hlcdc = dev_get_drvdata(dev->parent);
 244
 245         chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
 246         if (!chip)
 247                 return -ENOMEM;
 248
 249         ret = clk_prepare_enable(hlcdc->periph_clk);
 250         if (ret)
 251                 return ret;
 252
 253         match = of_match_node(atmel_hlcdc_dt_ids, dev->parent->of_node);
 254         if (match)
 255                 chip->errata = match->data;
 256
 257         chip->hlcdc = hlcdc;
 258         chip->chip.ops = &atmel_hlcdc_pwm_ops;
 259         chip->chip.dev = dev;
 260         chip->chip.base = -1;
 261         chip->chip.npwm = 1;
 262         chip->chip.of_xlate = of_pwm_xlate_with_flags;
 263         chip->chip.of_pwm_n_cells = 3;
 264         chip->chip.can_sleep = 1;
 265
 266         ret = pwmchip_add(&chip->chip);
 267         if (ret) {
 268                 clk_disable_unprepare(hlcdc->periph_clk);
 269                 return ret;
 270         }
 271
 272         platform_set_drvdata(pdev, chip);
 273
 274         return 0;
 275 }
 276
 277 static int atmel_hlcdc_pwm_remove(struct platform_device *pdev)
 278 {
 279         struct atmel_hlcdc_pwm *chip = platform_get_drvdata(pdev);
 280         int ret;
 281
 282         ret = pwmchip_remove(&chip->chip);
 283         if (ret)
 284                 return ret;
 285
 286         clk_disable_unprepare(chip->hlcdc->periph_clk);
 287
 288         return 0;
 289 }
 290
 291 static const struct of_device_id atmel_hlcdc_pwm_dt_ids[] = {
 292         { .compatible = "atmel,hlcdc-pwm" },
 293         { /* sentinel */ },
 294 };
 295
 296 static struct platform_driver atmel_hlcdc_pwm_driver = {
 297         .driver = {
 298                 .name = "atmel-hlcdc-pwm",
 299                 .of_match_table = atmel_hlcdc_pwm_dt_ids,
 300         },
 301         .probe = atmel_hlcdc_pwm_probe,
 302         .remove = atmel_hlcdc_pwm_remove,
 303 };
 304 module_platform_driver(atmel_hlcdc_pwm_driver);
 305
 306 MODULE_ALIAS("platform:atmel-hlcdc-pwm");
 307 MODULE_AUTHOR("Boris Brezillon <boris.brezillon@free-electrons.com>");
 308 MODULE_DESCRIPTION("Atmel HLCDC PWM driver");
 309 MODULE_LICENSE("GPL v2");