drivers/pwm/pwm-jz4740.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
   4  *  JZ4740 platform PWM support
   5  *
   6  * Limitations:
   7  * - The .apply callback doesn't complete the currently running period before
   8  *   reconfiguring the hardware.
   9  */
  10
  11 #include <linux/clk.h>
  12 #include <linux/err.h>
  13 #include <linux/gpio.h>
  14 #include <linux/kernel.h>
  15 #include <linux/mfd/ingenic-tcu.h>
  16 #include <linux/mfd/syscon.h>
  17 #include <linux/module.h>
  18 #include <linux/of.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/pwm.h>
  21 #include <linux/regmap.h>
  22
  23 struct soc_info {
  24         unsigned int num_pwms;
  25 };
  26
  27 struct jz4740_pwm_chip {
  28         struct regmap *map;
  29         struct clk *clk[];
  30 };
  31
  32 static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
  33 {
  34         return pwmchip_get_drvdata(chip);
  35 }
  36
  37 static bool jz4740_pwm_can_use_chn(struct pwm_chip *chip, unsigned int channel)
  38 {
  39         /* Enable all TCU channels for PWM use by default except channels 0/1 */
  40         u32 pwm_channels_mask = GENMASK(chip->npwm - 1, 2);
  41
  42         device_property_read_u32(pwmchip_parent(chip)->parent,
  43                                  "ingenic,pwm-channels-mask",
  44                                  &pwm_channels_mask);
  45
  46         return !!(pwm_channels_mask & BIT(channel));
  47 }
  48
  49 static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
  50 {
  51         struct jz4740_pwm_chip *jz = to_jz4740(chip);
  52         struct clk *clk;
  53         char name[16];
  54         int err;
  55
  56         if (!jz4740_pwm_can_use_chn(chip, pwm->hwpwm))
  57                 return -EBUSY;
  58
  59         snprintf(name, sizeof(name), "timer%u", pwm->hwpwm);
  60
  61         clk = clk_get(pwmchip_parent(chip), name);
  62         if (IS_ERR(clk)) {
  63                 dev_err(pwmchip_parent(chip),
  64                         "error %pe: Failed to get clock\n", clk);
  65                 return PTR_ERR(clk);
  66         }
  67
  68         err = clk_prepare_enable(clk);
  69         if (err < 0) {
  70                 clk_put(clk);
  71                 return err;
  72         }
  73
  74         jz->clk[pwm->hwpwm] = clk;
  75
  76         return 0;
  77 }
  78
  79 static void jz4740_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
  80 {
  81         struct jz4740_pwm_chip *jz = to_jz4740(chip);
  82         struct clk *clk = jz->clk[pwm->hwpwm];
  83
  84         clk_disable_unprepare(clk);
  85         clk_put(clk);
  86 }
  87
  88 static int jz4740_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
  89 {
  90         struct jz4740_pwm_chip *jz = to_jz4740(chip);
  91
  92         /* Enable PWM output */
  93         regmap_set_bits(jz->map, TCU_REG_TCSRc(pwm->hwpwm), TCU_TCSR_PWM_EN);
  94
  95         /* Start counter */
  96         regmap_write(jz->map, TCU_REG_TESR, BIT(pwm->hwpwm));
  97
  98         return 0;
  99 }
 100
 101 static void jz4740_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
 102 {
 103         struct jz4740_pwm_chip *jz = to_jz4740(chip);
 104
 105         /*
 106          * Set duty > period. This trick allows the TCU channels in TCU2 mode to
 107          * properly return to their init level.
 108          */
 109         regmap_write(jz->map, TCU_REG_TDHRc(pwm->hwpwm), 0xffff);
 110         regmap_write(jz->map, TCU_REG_TDFRc(pwm->hwpwm), 0x0);
 111
 112         /*
 113          * Disable PWM output.
 114          * In TCU2 mode (channel 1/2 on JZ4750+), this must be done before the
 115          * counter is stopped, while in TCU1 mode the order does not matter.
 116          */
 117         regmap_clear_bits(jz->map, TCU_REG_TCSRc(pwm->hwpwm), TCU_TCSR_PWM_EN);
 118
 119         /* Stop counter */
 120         regmap_write(jz->map, TCU_REG_TECR, BIT(pwm->hwpwm));
 121 }
 122
 123 static int jz4740_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 124                             const struct pwm_state *state)
 125 {
 126         struct jz4740_pwm_chip *jz = to_jz4740(chip);
 127         unsigned long long tmp = 0xffffull * NSEC_PER_SEC;
 128         struct clk *clk = jz->clk[pwm->hwpwm];
 129         unsigned long period, duty;
 130         long rate;
 131         int err;
 132
 133         /*
 134          * Limit the clock to a maximum rate that still gives us a period value
 135          * which fits in 16 bits.
 136          */
 137         do_div(tmp, state->period);
 138
 139         /*
 140          * /!\ IMPORTANT NOTE:
 141          * -------------------
 142          * This code relies on the fact that clk_round_rate() will always round
 143          * down, which is not a valid assumption given by the clk API, but only
 144          * happens to be true with the clk drivers used for Ingenic SoCs.
 145          *
 146          * Right now, there is no alternative as the clk API does not have a
 147          * round-down function (and won't have one for a while), but if it ever
 148          * comes to light, a round-down function should be used instead.
 149          */
 150         rate = clk_round_rate(clk, tmp);
 151         if (rate < 0) {
 152                 dev_err(pwmchip_parent(chip), "Unable to round rate: %ld\n", rate);
 153                 return rate;
 154         }
 155
 156         /* Calculate period value */
 157         tmp = (unsigned long long)rate * state->period;
 158         do_div(tmp, NSEC_PER_SEC);
 159         period = tmp;
 160
 161         /* Calculate duty value */
 162         tmp = (unsigned long long)rate * state->duty_cycle;
 163         do_div(tmp, NSEC_PER_SEC);
 164         duty = tmp;
 165
 166         if (duty >= period)
 167                 duty = period - 1;
 168
 169         jz4740_pwm_disable(chip, pwm);
 170
 171         err = clk_set_rate(clk, rate);
 172         if (err) {
 173                 dev_err(pwmchip_parent(chip), "Unable to set rate: %d\n", err);
 174                 return err;
 175         }
 176
 177         /* Reset counter to 0 */
 178         regmap_write(jz->map, TCU_REG_TCNTc(pwm->hwpwm), 0);
 179
 180         /* Set duty */
 181         regmap_write(jz->map, TCU_REG_TDHRc(pwm->hwpwm), duty);
 182
 183         /* Set period */
 184         regmap_write(jz->map, TCU_REG_TDFRc(pwm->hwpwm), period);
 185
 186         /* Set abrupt shutdown */
 187         regmap_set_bits(jz->map, TCU_REG_TCSRc(pwm->hwpwm),
 188                         TCU_TCSR_PWM_SD);
 189
 190         /*
 191          * Set polarity.
 192          *
 193          * The PWM starts in inactive state until the internal timer reaches the
 194          * duty value, then becomes active until the timer reaches the period
 195          * value. In theory, we should then use (period - duty) as the real duty
 196          * value, as a high duty value would otherwise result in the PWM pin
 197          * being inactive most of the time.
 198          *
 199          * Here, we don't do that, and instead invert the polarity of the PWM
 200          * when it is active. This trick makes the PWM start with its active
 201          * state instead of its inactive state.
 202          */
 203         if ((state->polarity == PWM_POLARITY_NORMAL) ^ state->enabled)
 204                 regmap_clear_bits(jz->map, TCU_REG_TCSRc(pwm->hwpwm),
 205                                   TCU_TCSR_PWM_INITL_HIGH);
 206         else
 207                 regmap_set_bits(jz->map, TCU_REG_TCSRc(pwm->hwpwm),
 208                                 TCU_TCSR_PWM_INITL_HIGH);
 209
 210         if (state->enabled)
 211                 jz4740_pwm_enable(chip, pwm);
 212
 213         return 0;
 214 }
 215
 216 static const struct pwm_ops jz4740_pwm_ops = {
 217         .request = jz4740_pwm_request,
 218         .free = jz4740_pwm_free,
 219         .apply = jz4740_pwm_apply,
 220 };
 221
 222 static int jz4740_pwm_probe(struct platform_device *pdev)
 223 {
 224         struct device *dev = &pdev->dev;
 225         struct pwm_chip *chip;
 226         struct jz4740_pwm_chip *jz;
 227         const struct soc_info *info;
 228
 229         info = device_get_match_data(dev);
 230         if (!info)
 231                 return -EINVAL;
 232
 233         chip = devm_pwmchip_alloc(dev, info->num_pwms, struct_size(jz, clk, info->num_pwms));
 234         if (IS_ERR(chip))
 235                 return PTR_ERR(chip);
 236         jz = to_jz4740(chip);
 237
 238         jz->map = device_node_to_regmap(dev->parent->of_node);
 239         if (IS_ERR(jz->map)) {
 240                 dev_err(dev, "regmap not found: %ld\n", PTR_ERR(jz->map));
 241                 return PTR_ERR(jz->map);
 242         }
 243
 244         chip->ops = &jz4740_pwm_ops;
 245
 246         return devm_pwmchip_add(dev, chip);
 247 }
 248
 249 static const struct soc_info jz4740_soc_info = {
 250         .num_pwms = 8,
 251 };
 252
 253 static const struct soc_info jz4725b_soc_info = {
 254         .num_pwms = 6,
 255 };
 256
 257 static const struct soc_info x1000_soc_info = {
 258         .num_pwms = 5,
 259 };
 260
 261 static const struct of_device_id jz4740_pwm_dt_ids[] = {
 262         { .compatible = "ingenic,jz4740-pwm", .data = &jz4740_soc_info },
 263         { .compatible = "ingenic,jz4725b-pwm", .data = &jz4725b_soc_info },
 264         { .compatible = "ingenic,x1000-pwm", .data = &x1000_soc_info },
 265         {},
 266 };
 267 MODULE_DEVICE_TABLE(of, jz4740_pwm_dt_ids);
 268
 269 static struct platform_driver jz4740_pwm_driver = {
 270         .driver = {
 271                 .name = "jz4740-pwm",
 272                 .of_match_table = jz4740_pwm_dt_ids,
 273         },
 274         .probe = jz4740_pwm_probe,
 275 };
 276 module_platform_driver(jz4740_pwm_driver);
 277
 278 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 279 MODULE_DESCRIPTION("Ingenic JZ4740 PWM driver");
 280 MODULE_ALIAS("platform:jz4740-pwm");
 281 MODULE_LICENSE("GPL");