Quelle  pwm-keembay.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
/*
 * Intel Keem Bay PWM driver
 *
 * Copyright (C) 2020 Intel Corporation
 * Authors: Lai Poey Seng <poey.seng.lai@intel.com>
 *          Vineetha G. Jaya Kumaran <vineetha.g.jaya.kumaran@intel.com>
 *
 * Limitations:
 * - Upon disabling a channel, the currently running
 *   period will not be completed. However, upon
 *   reconfiguration of the duty cycle/period, the
 *   currently running period will be completed first.
 */

#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/regmap.h>

#define KMB_TOTAL_PWM_CHANNELS  6
#define KMB_PWM_COUNT_MAX  U16_MAX
#define KMB_PWM_EN_BIT   BIT(31)

/* Mask */
#define KMB_PWM_HIGH_MASK  GENMASK(31, 16)
#define KMB_PWM_LOW_MASK  GENMASK(15, 0)
#define KMB_PWM_LEADIN_MASK  GENMASK(30, 0)

/* PWM Register offset */
#define KMB_PWM_LEADIN_OFFSET(ch) (0x00 + 4 * (ch))
#define KMB_PWM_HIGHLOW_OFFSET(ch) (0x20 + 4 * (ch))

struct keembay_pwm {
 struct device *dev;
 struct clk *clk;
 void __iomem *base;
};

static inline struct keembay_pwm *to_keembay_pwm_dev(struct pwm_chip *chip)
{
 return pwmchip_get_drvdata(chip);
}

static void keembay_clk_unprepare(void *data)
{
 clk_disable_unprepare(data);
}

static int keembay_clk_enable(struct device *dev, struct clk *clk)
{
 int ret;

 ret = clk_prepare_enable(clk);
 if (ret)
  return ret;

 return devm_add_action_or_reset(dev, keembay_clk_unprepare, clk);
}

/*
 * With gcc 10, CONFIG_CC_OPTIMIZE_FOR_SIZE and only "inline" instead of
 * "__always_inline" this fails to compile because the compiler doesn't notice
 * for all valid masks (e.g. KMB_PWM_LEADIN_MASK) that they are ok.
 */
static __always_inline void keembay_pwm_update_bits(struct keembay_pwm *priv, u32 mask,
        u32 val, u32 offset)
{
 u32 buff = readl(priv->base + offset);

 buff = u32_replace_bits(buff, val, mask);
 writel(buff, priv->base + offset);
}

static void keembay_pwm_enable(struct keembay_pwm *priv, int ch)
{
 keembay_pwm_update_bits(priv, KMB_PWM_EN_BIT, 1,
    KMB_PWM_LEADIN_OFFSET(ch));
}

static void keembay_pwm_disable(struct keembay_pwm *priv, int ch)
{
 keembay_pwm_update_bits(priv, KMB_PWM_EN_BIT, 0,
    KMB_PWM_LEADIN_OFFSET(ch));
}

static int keembay_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
     struct pwm_state *state)
{
 struct keembay_pwm *priv = to_keembay_pwm_dev(chip);
 unsigned long long high, low;
 unsigned long clk_rate;
 u32 highlow;

 clk_rate = clk_get_rate(priv->clk);

 /* Read channel enabled status */
 highlow = readl(priv->base + KMB_PWM_LEADIN_OFFSET(pwm->hwpwm));
 if (highlow & KMB_PWM_EN_BIT)
  state->enabled = true;
 else
  state->enabled = false;

 /* Read period and duty cycle */
 highlow = readl(priv->base + KMB_PWM_HIGHLOW_OFFSET(pwm->hwpwm));
 low = FIELD_GET(KMB_PWM_LOW_MASK, highlow) * NSEC_PER_SEC;
 high = FIELD_GET(KMB_PWM_HIGH_MASK, highlow) * NSEC_PER_SEC;
 state->duty_cycle = DIV_ROUND_UP_ULL(high, clk_rate);
 state->period = DIV_ROUND_UP_ULL(high + low, clk_rate);
 state->polarity = PWM_POLARITY_NORMAL;

 return 0;
}

static int keembay_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
        const struct pwm_state *state)
{
 struct keembay_pwm *priv = to_keembay_pwm_dev(chip);
 struct pwm_state current_state;
 unsigned long long div;
 unsigned long clk_rate;
 u32 pwm_count = 0;
 u16 high, low;

 if (state->polarity != PWM_POLARITY_NORMAL)
  return -EINVAL;

 /*
  * Configure the pwm repeat count as infinite at (15:0) and leadin
  * low time as 0 at (30:16), which is in terms of clock cycles.
 */
 keembay_pwm_update_bits(priv, KMB_PWM_LEADIN_MASK, 0,
    KMB_PWM_LEADIN_OFFSET(pwm->hwpwm));

 keembay_pwm_get_state(chip, pwm, ¤t_state);

 if (!state->enabled) {
  if (current_state.enabled)
   keembay_pwm_disable(priv, pwm->hwpwm);
  return 0;
 }

 /*
  * The upper 16 bits and lower 16 bits of the KMB_PWM_HIGHLOW_OFFSET
  * register contain the high time and low time of waveform accordingly.
  * All the values are in terms of clock cycles.
 */

 clk_rate = clk_get_rate(priv->clk);
 div = clk_rate * state->duty_cycle;
 div = DIV_ROUND_DOWN_ULL(div, NSEC_PER_SEC);
 if (div > KMB_PWM_COUNT_MAX)
  return -ERANGE;

 high = div;
 div = clk_rate * state->period;
 div = DIV_ROUND_DOWN_ULL(div, NSEC_PER_SEC);
 div = div - high;
 if (div > KMB_PWM_COUNT_MAX)
  return -ERANGE;

 low = div;

 pwm_count = FIELD_PREP(KMB_PWM_HIGH_MASK, high) |
      FIELD_PREP(KMB_PWM_LOW_MASK, low);

 writel(pwm_count, priv->base + KMB_PWM_HIGHLOW_OFFSET(pwm->hwpwm));

 if (state->enabled && !current_state.enabled)
  keembay_pwm_enable(priv, pwm->hwpwm);

 return 0;
}

static const struct pwm_ops keembay_pwm_ops = {
 .apply = keembay_pwm_apply,
 .get_state = keembay_pwm_get_state,
};

static int keembay_pwm_probe(struct platform_device *pdev)
{
 struct device *dev = &pdev->dev;
 struct pwm_chip *chip;
 struct keembay_pwm *priv;
 int ret;

 chip = devm_pwmchip_alloc(dev, KMB_TOTAL_PWM_CHANNELS, sizeof(*priv));
 if (IS_ERR(chip))
  return PTR_ERR(chip);
 priv = to_keembay_pwm_dev(chip);

 priv->clk = devm_clk_get(dev, NULL);
 if (IS_ERR(priv->clk))
  return dev_err_probe(dev, PTR_ERR(priv->clk), "Failed to get clock\n");

 priv->base = devm_platform_ioremap_resource(pdev, 0);
 if (IS_ERR(priv->base))
  return PTR_ERR(priv->base);

 ret = keembay_clk_enable(dev, priv->clk);
 if (ret)
  return ret;

 chip->ops = &keembay_pwm_ops;

 ret = devm_pwmchip_add(dev, chip);
 if (ret)
  return dev_err_probe(dev, ret, "Failed to add PWM chip\n");

 return 0;
}

static const struct of_device_id keembay_pwm_of_match[] = {
 { .compatible = "intel,keembay-pwm" },
 { }
};
MODULE_DEVICE_TABLE(of, keembay_pwm_of_match);

static struct platform_driver keembay_pwm_driver = {
 .probe = keembay_pwm_probe,
 .driver = {
  .name = "pwm-keembay",
  .of_match_table = keembay_pwm_of_match,
 },
};
module_platform_driver(keembay_pwm_driver);

MODULE_ALIAS("platform:pwm-keembay");
MODULE_DESCRIPTION("Intel Keem Bay PWM driver");
MODULE_LICENSE("GPL v2");