drivers/pwm/pwm-keembay.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Intel Keem Bay PWM driver
   4  *
   5  * Copyright (C) 2020 Intel Corporation
   6  * Authors: Lai Poey Seng <poey.seng.lai@intel.com>
   7  *          Vineetha G. Jaya Kumaran <vineetha.g.jaya.kumaran@intel.com>
   8  *
   9  * Limitations:
  10  * - Upon disabling a channel, the currently running
  11  *   period will not be completed. However, upon
  12  *   reconfiguration of the duty cycle/period, the
  13  *   currently running period will be completed first.
  14  */
  15
  16 #include <linux/bitfield.h>
  17 #include <linux/clk.h>
  18 #include <linux/io.h>
  19 #include <linux/mod_devicetable.h>
  20 #include <linux/module.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/pwm.h>
  23 #include <linux/regmap.h>
  24
  25 #define KMB_TOTAL_PWM_CHANNELS          6
  26 #define KMB_PWM_COUNT_MAX               U16_MAX
  27 #define KMB_PWM_EN_BIT                  BIT(31)
  28
  29 /* Mask */
  30 #define KMB_PWM_HIGH_MASK               GENMASK(31, 16)
  31 #define KMB_PWM_LOW_MASK                GENMASK(15, 0)
  32 #define KMB_PWM_LEADIN_MASK             GENMASK(30, 0)
  33
  34 /* PWM Register offset */
  35 #define KMB_PWM_LEADIN_OFFSET(ch)       (0x00 + 4 * (ch))
  36 #define KMB_PWM_HIGHLOW_OFFSET(ch)      (0x20 + 4 * (ch))
  37
  38 struct keembay_pwm {
  39         struct pwm_chip chip;
  40         struct device *dev;
  41         struct clk *clk;
  42         void __iomem *base;
  43 };
  44
  45 static inline struct keembay_pwm *to_keembay_pwm_dev(struct pwm_chip *chip)
  46 {
  47         return container_of(chip, struct keembay_pwm, chip);
  48 }
  49
  50 static void keembay_clk_unprepare(void *data)
  51 {
  52         clk_disable_unprepare(data);
  53 }
  54
  55 static int keembay_clk_enable(struct device *dev, struct clk *clk)
  56 {
  57         int ret;
  58
  59         ret = clk_prepare_enable(clk);
  60         if (ret)
  61                 return ret;
  62
  63         return devm_add_action_or_reset(dev, keembay_clk_unprepare, clk);
  64 }
  65
  66 /*
  67  * With gcc 10, CONFIG_CC_OPTIMIZE_FOR_SIZE and only "inline" instead of
  68  * "__always_inline" this fails to compile because the compiler doesn't notice
  69  * for all valid masks (e.g. KMB_PWM_LEADIN_MASK) that they are ok.
  70  */
  71 static __always_inline void keembay_pwm_update_bits(struct keembay_pwm *priv, u32 mask,
  72                                            u32 val, u32 offset)
  73 {
  74         u32 buff = readl(priv->base + offset);
  75
  76         buff = u32_replace_bits(buff, val, mask);
  77         writel(buff, priv->base + offset);
  78 }
  79
  80 static void keembay_pwm_enable(struct keembay_pwm *priv, int ch)
  81 {
  82         keembay_pwm_update_bits(priv, KMB_PWM_EN_BIT, 1,
  83                                 KMB_PWM_LEADIN_OFFSET(ch));
  84 }
  85
  86 static void keembay_pwm_disable(struct keembay_pwm *priv, int ch)
  87 {
  88         keembay_pwm_update_bits(priv, KMB_PWM_EN_BIT, 0,
  89                                 KMB_PWM_LEADIN_OFFSET(ch));
  90 }
  91
  92 static int keembay_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
  93                                  struct pwm_state *state)
  94 {
  95         struct keembay_pwm *priv = to_keembay_pwm_dev(chip);
  96         unsigned long long high, low;
  97         unsigned long clk_rate;
  98         u32 highlow;
  99
 100         clk_rate = clk_get_rate(priv->clk);
 101
 102         /* Read channel enabled status */
 103         highlow = readl(priv->base + KMB_PWM_LEADIN_OFFSET(pwm->hwpwm));
 104         if (highlow & KMB_PWM_EN_BIT)
 105                 state->enabled = true;
 106         else
 107                 state->enabled = false;
 108
 109         /* Read period and duty cycle */
 110         highlow = readl(priv->base + KMB_PWM_HIGHLOW_OFFSET(pwm->hwpwm));
 111         low = FIELD_GET(KMB_PWM_LOW_MASK, highlow) * NSEC_PER_SEC;
 112         high = FIELD_GET(KMB_PWM_HIGH_MASK, highlow) * NSEC_PER_SEC;
 113         state->duty_cycle = DIV_ROUND_UP_ULL(high, clk_rate);
 114         state->period = DIV_ROUND_UP_ULL(high + low, clk_rate);
 115         state->polarity = PWM_POLARITY_NORMAL;
 116
 117         return 0;
 118 }
 119
 120 static int keembay_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 121                              const struct pwm_state *state)
 122 {
 123         struct keembay_pwm *priv = to_keembay_pwm_dev(chip);
 124         struct pwm_state current_state;
 125         unsigned long long div;
 126         unsigned long clk_rate;
 127         u32 pwm_count = 0;
 128         u16 high, low;
 129
 130         if (state->polarity != PWM_POLARITY_NORMAL)
 131                 return -EINVAL;
 132
 133         /*
 134          * Configure the pwm repeat count as infinite at (15:0) and leadin
 135          * low time as 0 at (30:16), which is in terms of clock cycles.
 136          */
 137         keembay_pwm_update_bits(priv, KMB_PWM_LEADIN_MASK, 0,
 138                                 KMB_PWM_LEADIN_OFFSET(pwm->hwpwm));
 139
 140         keembay_pwm_get_state(chip, pwm, &current_state);
 141
 142         if (!state->enabled) {
 143                 if (current_state.enabled)
 144                         keembay_pwm_disable(priv, pwm->hwpwm);
 145                 return 0;
 146         }
 147
 148         /*
 149          * The upper 16 bits and lower 16 bits of the KMB_PWM_HIGHLOW_OFFSET
 150          * register contain the high time and low time of waveform accordingly.
 151          * All the values are in terms of clock cycles.
 152          */
 153
 154         clk_rate = clk_get_rate(priv->clk);
 155         div = clk_rate * state->duty_cycle;
 156         div = DIV_ROUND_DOWN_ULL(div, NSEC_PER_SEC);
 157         if (div > KMB_PWM_COUNT_MAX)
 158                 return -ERANGE;
 159
 160         high = div;
 161         div = clk_rate * state->period;
 162         div = DIV_ROUND_DOWN_ULL(div, NSEC_PER_SEC);
 163         div = div - high;
 164         if (div > KMB_PWM_COUNT_MAX)
 165                 return -ERANGE;
 166
 167         low = div;
 168
 169         pwm_count = FIELD_PREP(KMB_PWM_HIGH_MASK, high) |
 170                     FIELD_PREP(KMB_PWM_LOW_MASK, low);
 171
 172         writel(pwm_count, priv->base + KMB_PWM_HIGHLOW_OFFSET(pwm->hwpwm));
 173
 174         if (state->enabled && !current_state.enabled)
 175                 keembay_pwm_enable(priv, pwm->hwpwm);
 176
 177         return 0;
 178 }
 179
 180 static const struct pwm_ops keembay_pwm_ops = {
 181         .apply = keembay_pwm_apply,
 182         .get_state = keembay_pwm_get_state,
 183 };
 184
 185 static int keembay_pwm_probe(struct platform_device *pdev)
 186 {
 187         struct device *dev = &pdev->dev;
 188         struct keembay_pwm *priv;
 189         int ret;
 190
 191         priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
 192         if (!priv)
 193                 return -ENOMEM;
 194
 195         priv->clk = devm_clk_get(dev, NULL);
 196         if (IS_ERR(priv->clk))
 197                 return dev_err_probe(dev, PTR_ERR(priv->clk), "Failed to get clock\n");
 198
 199         priv->base = devm_platform_ioremap_resource(pdev, 0);
 200         if (IS_ERR(priv->base))
 201                 return PTR_ERR(priv->base);
 202
 203         ret = keembay_clk_enable(dev, priv->clk);
 204         if (ret)
 205                 return ret;
 206
 207         priv->chip.dev = dev;
 208         priv->chip.ops = &keembay_pwm_ops;
 209         priv->chip.npwm = KMB_TOTAL_PWM_CHANNELS;
 210
 211         ret = devm_pwmchip_add(dev, &priv->chip);
 212         if (ret)
 213                 return dev_err_probe(dev, ret, "Failed to add PWM chip\n");
 214
 215         return 0;
 216 }
 217
 218 static const struct of_device_id keembay_pwm_of_match[] = {
 219         { .compatible = "intel,keembay-pwm" },
 220         { }
 221 };
 222 MODULE_DEVICE_TABLE(of, keembay_pwm_of_match);
 223
 224 static struct platform_driver keembay_pwm_driver = {
 225         .probe  = keembay_pwm_probe,
 226         .driver = {
 227                 .name = "pwm-keembay",
 228                 .of_match_table = keembay_pwm_of_match,
 229         },
 230 };
 231 module_platform_driver(keembay_pwm_driver);
 232
 233 MODULE_ALIAS("platform:pwm-keembay");
 234 MODULE_DESCRIPTION("Intel Keem Bay PWM driver");
 235 MODULE_LICENSE("GPL v2");