drivers/pwm/pwm-sunplus.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * PWM device driver for SUNPLUS SP7021 SoC
   4  *
   5  * Links:
   6  *   Reference Manual:
   7  *   https://sunplus-tibbo.atlassian.net/wiki/spaces/doc/overview
   8  *
   9  *   Reference Manual(PWM module):
  10  *   https://sunplus.atlassian.net/wiki/spaces/doc/pages/461144198/12.+Pulse+Width+Modulation+PWM
  11  *
  12  * Limitations:
  13  * - Only supports normal polarity.
  14  * - It output low when PWM channel disabled.
  15  * - When the parameters change, current running period will not be completed
  16  *     and run new settings immediately.
  17  * - In .apply() PWM output need to write register FREQ and DUTY. When first write FREQ
  18  *     done and not yet write DUTY, it has short timing gap use new FREQ and old DUTY.
  19  *
  20  * Author: Hammer Hsieh <hammerh0314@gmail.com>
  21  */
  22 #include <linux/bitfield.h>
  23 #include <linux/clk.h>
  24 #include <linux/io.h>
  25 #include <linux/kernel.h>
  26 #include <linux/module.h>
  27 #include <linux/platform_device.h>
  28 #include <linux/pwm.h>
  29
  30 #define SP7021_PWM_MODE0                0x000
  31 #define SP7021_PWM_MODE0_PWMEN(ch)      BIT(ch)
  32 #define SP7021_PWM_MODE0_BYPASS(ch)     BIT(8 + (ch))
  33 #define SP7021_PWM_MODE1                0x004
  34 #define SP7021_PWM_MODE1_CNT_EN(ch)     BIT(ch)
  35 #define SP7021_PWM_FREQ(ch)             (0x008 + 4 * (ch))
  36 #define SP7021_PWM_FREQ_MAX             GENMASK(15, 0)
  37 #define SP7021_PWM_DUTY(ch)             (0x018 + 4 * (ch))
  38 #define SP7021_PWM_DUTY_DD_SEL(ch)      FIELD_PREP(GENMASK(9, 8), ch)
  39 #define SP7021_PWM_DUTY_MAX             GENMASK(7, 0)
  40 #define SP7021_PWM_DUTY_MASK            SP7021_PWM_DUTY_MAX
  41 #define SP7021_PWM_FREQ_SCALER          256
  42 #define SP7021_PWM_NUM                  4
  43
  44 struct sunplus_pwm {
  45         struct pwm_chip chip;
  46         void __iomem *base;
  47         struct clk *clk;
  48 };
  49
  50 static inline struct sunplus_pwm *to_sunplus_pwm(struct pwm_chip *chip)
  51 {
  52         return container_of(chip, struct sunplus_pwm, chip);
  53 }
  54
  55 static int sunplus_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
  56                              const struct pwm_state *state)
  57 {
  58         struct sunplus_pwm *priv = to_sunplus_pwm(chip);
  59         u32 dd_freq, duty, mode0, mode1;
  60         u64 clk_rate;
  61
  62         if (state->polarity != pwm->state.polarity)
  63                 return -EINVAL;
  64
  65         if (!state->enabled) {
  66                 /* disable pwm channel output */
  67                 mode0 = readl(priv->base + SP7021_PWM_MODE0);
  68                 mode0 &= ~SP7021_PWM_MODE0_PWMEN(pwm->hwpwm);
  69                 writel(mode0, priv->base + SP7021_PWM_MODE0);
  70                 /* disable pwm channel clk source */
  71                 mode1 = readl(priv->base + SP7021_PWM_MODE1);
  72                 mode1 &= ~SP7021_PWM_MODE1_CNT_EN(pwm->hwpwm);
  73                 writel(mode1, priv->base + SP7021_PWM_MODE1);
  74                 return 0;
  75         }
  76
  77         clk_rate = clk_get_rate(priv->clk);
  78
  79         /*
  80          * The following calculations might overflow if clk is bigger
  81          * than 256 GHz. In practise it's 202.5MHz, so this limitation
  82          * is only theoretic.
  83          */
  84         if (clk_rate > (u64)SP7021_PWM_FREQ_SCALER * NSEC_PER_SEC)
  85                 return -EINVAL;
  86
  87         /*
  88          * With clk_rate limited above we have dd_freq <= state->period,
  89          * so this cannot overflow.
  90          */
  91         dd_freq = mul_u64_u64_div_u64(clk_rate, state->period, (u64)SP7021_PWM_FREQ_SCALER
  92                                 * NSEC_PER_SEC);
  93
  94         if (dd_freq == 0)
  95                 return -EINVAL;
  96
  97         if (dd_freq > SP7021_PWM_FREQ_MAX)
  98                 dd_freq = SP7021_PWM_FREQ_MAX;
  99
 100         writel(dd_freq, priv->base + SP7021_PWM_FREQ(pwm->hwpwm));
 101
 102         /* cal and set pwm duty */
 103         mode0 = readl(priv->base + SP7021_PWM_MODE0);
 104         mode0 |= SP7021_PWM_MODE0_PWMEN(pwm->hwpwm);
 105         mode1 = readl(priv->base + SP7021_PWM_MODE1);
 106         mode1 |= SP7021_PWM_MODE1_CNT_EN(pwm->hwpwm);
 107         if (state->duty_cycle == state->period) {
 108                 /* PWM channel output = high */
 109                 mode0 |= SP7021_PWM_MODE0_BYPASS(pwm->hwpwm);
 110                 duty = SP7021_PWM_DUTY_DD_SEL(pwm->hwpwm) | SP7021_PWM_DUTY_MAX;
 111         } else {
 112                 mode0 &= ~SP7021_PWM_MODE0_BYPASS(pwm->hwpwm);
 113                 /*
 114                  * duty_ns <= period_ns 27 bits, clk_rate 28 bits, won't overflow.
 115                  */
 116                 duty = mul_u64_u64_div_u64(state->duty_cycle, clk_rate,
 117                                            (u64)dd_freq * NSEC_PER_SEC);
 118                 duty = SP7021_PWM_DUTY_DD_SEL(pwm->hwpwm) | duty;
 119         }
 120         writel(duty, priv->base + SP7021_PWM_DUTY(pwm->hwpwm));
 121         writel(mode1, priv->base + SP7021_PWM_MODE1);
 122         writel(mode0, priv->base + SP7021_PWM_MODE0);
 123
 124         return 0;
 125 }
 126
 127 static void sunplus_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 128                                   struct pwm_state *state)
 129 {
 130         struct sunplus_pwm *priv = to_sunplus_pwm(chip);
 131         u32 mode0, dd_freq, duty;
 132         u64 clk_rate;
 133
 134         mode0 = readl(priv->base + SP7021_PWM_MODE0);
 135
 136         if (mode0 & BIT(pwm->hwpwm)) {
 137                 clk_rate = clk_get_rate(priv->clk);
 138                 dd_freq = readl(priv->base + SP7021_PWM_FREQ(pwm->hwpwm));
 139                 duty = readl(priv->base + SP7021_PWM_DUTY(pwm->hwpwm));
 140                 duty = FIELD_GET(SP7021_PWM_DUTY_MASK, duty);
 141                 /*
 142                  * dd_freq 16 bits, SP7021_PWM_FREQ_SCALER 8 bits
 143                  * NSEC_PER_SEC 30 bits, won't overflow.
 144                  */
 145                 state->period = DIV64_U64_ROUND_UP((u64)dd_freq * (u64)SP7021_PWM_FREQ_SCALER
 146                                                 * NSEC_PER_SEC, clk_rate);
 147                 /*
 148                  * dd_freq 16 bits, duty 8 bits, NSEC_PER_SEC 30 bits, won't overflow.
 149                  */
 150                 state->duty_cycle = DIV64_U64_ROUND_UP((u64)dd_freq * (u64)duty * NSEC_PER_SEC,
 151                                                        clk_rate);
 152                 state->enabled = true;
 153         } else {
 154                 state->enabled = false;
 155         }
 156
 157         state->polarity = PWM_POLARITY_NORMAL;
 158 }
 159
 160 static const struct pwm_ops sunplus_pwm_ops = {
 161         .apply = sunplus_pwm_apply,
 162         .get_state = sunplus_pwm_get_state,
 163         .owner = THIS_MODULE,
 164 };
 165
 166 static void sunplus_pwm_clk_release(void *data)
 167 {
 168         struct clk *clk = data;
 169
 170         clk_disable_unprepare(clk);
 171 }
 172
 173 static int sunplus_pwm_probe(struct platform_device *pdev)
 174 {
 175         struct device *dev = &pdev->dev;
 176         struct sunplus_pwm *priv;
 177         int ret;
 178
 179         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 180         if (!priv)
 181                 return -ENOMEM;
 182
 183         priv->base = devm_platform_ioremap_resource(pdev, 0);
 184         if (IS_ERR(priv->base))
 185                 return PTR_ERR(priv->base);
 186
 187         priv->clk = devm_clk_get(dev, NULL);
 188         if (IS_ERR(priv->clk))
 189                 return dev_err_probe(dev, PTR_ERR(priv->clk),
 190                                      "get pwm clock failed\n");
 191
 192         ret = clk_prepare_enable(priv->clk);
 193         if (ret < 0) {
 194                 dev_err(dev, "failed to enable clock: %d\n", ret);
 195                 return ret;
 196         }
 197
 198         ret = devm_add_action_or_reset(dev, sunplus_pwm_clk_release, priv->clk);
 199         if (ret < 0) {
 200                 dev_err(dev, "failed to release clock: %d\n", ret);
 201                 return ret;
 202         }
 203
 204         priv->chip.dev = dev;
 205         priv->chip.ops = &sunplus_pwm_ops;
 206         priv->chip.npwm = SP7021_PWM_NUM;
 207
 208         ret = devm_pwmchip_add(dev, &priv->chip);
 209         if (ret < 0)
 210                 return dev_err_probe(dev, ret, "Cannot register sunplus PWM\n");
 211
 212         return 0;
 213 }
 214
 215 static const struct of_device_id sunplus_pwm_of_match[] = {
 216         { .compatible = "sunplus,sp7021-pwm", },
 217         {}
 218 };
 219 MODULE_DEVICE_TABLE(of, sunplus_pwm_of_match);
 220
 221 static struct platform_driver sunplus_pwm_driver = {
 222         .probe          = sunplus_pwm_probe,
 223         .driver         = {
 224                 .name   = "sunplus-pwm",
 225                 .of_match_table = sunplus_pwm_of_match,
 226         },
 227 };
 228 module_platform_driver(sunplus_pwm_driver);
 229
 230 MODULE_DESCRIPTION("Sunplus SoC PWM Driver");
 231 MODULE_AUTHOR("Hammer Hsieh <hammerh0314@gmail.com>");
 232 MODULE_LICENSE("GPL");