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// SPDX-License-Identifier: GPL-2.0
/*
* PWM device driver for SUNPLUS SP7021 SoC
*
* Links:
* Reference Manual:
* https://sunplus-tibbo.atlassian.net/wiki/spaces/doc/overview
*
* Reference Manual(PWM module):
* https://sunplus.atlassian.net/wiki/spaces/doc/pages/461144198/12.+Pulse+Width+Modulation+PWM
*
* Limitations:
* - Only supports normal polarity.
* - It output low when PWM channel disabled.
* - When the parameters change, current running period will not be completed
* and run new settings immediately.
* - In .apply() PWM output need to write register FREQ and DUTY. When first write FREQ
* done and not yet write DUTY, it has short timing gap use new FREQ and old DUTY.
*
* Author: Hammer Hsieh <hammerh0314@gmail.com>
*/
#include <linux/bitfield.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#define SP7021_PWM_MODE0 0x000
#define SP7021_PWM_MODE0_PWMEN(ch) BIT(ch)
#define SP7021_PWM_MODE0_BYPASS(ch) BIT(8 + (ch))
#define SP7021_PWM_MODE1 0x004
#define SP7021_PWM_MODE1_CNT_EN(ch) BIT(ch)
#define SP7021_PWM_FREQ(ch) (0x008 + 4 * (ch))
#define SP7021_PWM_FREQ_MAX GENMASK(15, 0)
#define SP7021_PWM_DUTY(ch) (0x018 + 4 * (ch))
#define SP7021_PWM_DUTY_DD_SEL(ch) FIELD_PREP(GENMASK(9, 8), ch)
#define SP7021_PWM_DUTY_MAX GENMASK(7, 0)
#define SP7021_PWM_DUTY_MASK SP7021_PWM_DUTY_MAX
#define SP7021_PWM_FREQ_SCALER 256
#define SP7021_PWM_NUM 4
struct sunplus_pwm {
struct pwm_chip chip;
void __iomem *base;
struct clk *clk;
};
static inline struct sunplus_pwm *to_sunplus_pwm(struct pwm_chip *chip)
{
return container_of(chip, struct sunplus_pwm, chip);
}
static int sunplus_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
const struct pwm_state *state)
{
struct sunplus_pwm *priv = to_sunplus_pwm(chip);
u32 dd_freq, duty, mode0, mode1;
u64 clk_rate;
if (state->polarity != pwm->state.polarity)
return -EINVAL;
if (!state->enabled) {
/* disable pwm channel output */
mode0 = readl(priv->base + SP7021_PWM_MODE0);
mode0 &= ~SP7021_PWM_MODE0_PWMEN(pwm->hwpwm);
writel(mode0, priv->base + SP7021_PWM_MODE0);
/* disable pwm channel clk source */
mode1 = readl(priv->base + SP7021_PWM_MODE1);
mode1 &= ~SP7021_PWM_MODE1_CNT_EN(pwm->hwpwm);
writel(mode1, priv->base + SP7021_PWM_MODE1);
return 0;
}
clk_rate = clk_get_rate(priv->clk);
/*
* The following calculations might overflow if clk is bigger
* than 256 GHz. In practise it's 202.5MHz, so this limitation
* is only theoretic.
*/
if (clk_rate > (u64)SP7021_PWM_FREQ_SCALER * NSEC_PER_SEC)
return -EINVAL;
/*
* With clk_rate limited above we have dd_freq <= state->period,
* so this cannot overflow.
*/
dd_freq = mul_u64_u64_div_u64(clk_rate, state->period, (u64)SP7021_PWM_FREQ_SCALER
* NSEC_PER_SEC);
if (dd_freq == 0)
return -EINVAL;
if (dd_freq > SP7021_PWM_FREQ_MAX)
dd_freq = SP7021_PWM_FREQ_MAX;
writel(dd_freq, priv->base + SP7021_PWM_FREQ(pwm->hwpwm));
/* cal and set pwm duty */
mode0 = readl(priv->base + SP7021_PWM_MODE0);
mode0 |= SP7021_PWM_MODE0_PWMEN(pwm->hwpwm);
mode1 = readl(priv->base + SP7021_PWM_MODE1);
mode1 |= SP7021_PWM_MODE1_CNT_EN(pwm->hwpwm);
if (state->duty_cycle == state->period) {
/* PWM channel output = high */
mode0 |= SP7021_PWM_MODE0_BYPASS(pwm->hwpwm);
duty = SP7021_PWM_DUTY_DD_SEL(pwm->hwpwm) | SP7021_PWM_DUTY_MAX;
} else {
mode0 &= ~SP7021_PWM_MODE0_BYPASS(pwm->hwpwm);
/*
* duty_ns <= period_ns 27 bits, clk_rate 28 bits, won't overflow.
*/
duty = mul_u64_u64_div_u64(state->duty_cycle, clk_rate,
(u64)dd_freq * NSEC_PER_SEC);
duty = SP7021_PWM_DUTY_DD_SEL(pwm->hwpwm) | duty;
}
writel(duty, priv->base + SP7021_PWM_DUTY(pwm->hwpwm));
writel(mode1, priv->base + SP7021_PWM_MODE1);
writel(mode0, priv->base + SP7021_PWM_MODE0);
return 0;
}
static int sunplus_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_state *state)
{
struct sunplus_pwm *priv = to_sunplus_pwm(chip);
u32 mode0, dd_freq, duty;
u64 clk_rate;
mode0 = readl(priv->base + SP7021_PWM_MODE0);
if (mode0 & BIT(pwm->hwpwm)) {
clk_rate = clk_get_rate(priv->clk);
dd_freq = readl(priv->base + SP7021_PWM_FREQ(pwm->hwpwm));
duty = readl(priv->base + SP7021_PWM_DUTY(pwm->hwpwm));
duty = FIELD_GET(SP7021_PWM_DUTY_MASK, duty);
/*
* dd_freq 16 bits, SP7021_PWM_FREQ_SCALER 8 bits
* NSEC_PER_SEC 30 bits, won't overflow.
*/
state->period = DIV64_U64_ROUND_UP((u64)dd_freq * (u64)SP7021_PWM_FREQ_SCALER
* NSEC_PER_SEC, clk_rate);
/*
* dd_freq 16 bits, duty 8 bits, NSEC_PER_SEC 30 bits, won't overflow.
*/
state->duty_cycle = DIV64_U64_ROUND_UP((u64)dd_freq * (u64)duty * NSEC_PER_SEC,
clk_rate);
state->enabled = true;
} else {
state->enabled = false;
}
state->polarity = PWM_POLARITY_NORMAL;
return 0;
}
static const struct pwm_ops sunplus_pwm_ops = {
.apply = sunplus_pwm_apply,
.get_state = sunplus_pwm_get_state,
.owner = THIS_MODULE,
};
static void sunplus_pwm_clk_release(void *data)
{
struct clk *clk = data;
clk_disable_unprepare(clk);
}
static int sunplus_pwm_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct sunplus_pwm *priv;
int ret;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(priv->base))
return PTR_ERR(priv->base);
priv->clk = devm_clk_get(dev, NULL);
if (IS_ERR(priv->clk))
return dev_err_probe(dev, PTR_ERR(priv->clk),
"get pwm clock failed\n");
ret = clk_prepare_enable(priv->clk);
if (ret < 0) {
dev_err(dev, "failed to enable clock: %d\n", ret);
return ret;
}
ret = devm_add_action_or_reset(dev, sunplus_pwm_clk_release, priv->clk);
if (ret < 0) {
dev_err(dev, "failed to release clock: %d\n", ret);
return ret;
}
priv->chip.dev = dev;
priv->chip.ops = &sunplus_pwm_ops;
priv->chip.npwm = SP7021_PWM_NUM;
ret = devm_pwmchip_add(dev, &priv->chip);
if (ret < 0)
return dev_err_probe(dev, ret, "Cannot register sunplus PWM\n");
return 0;
}
static const struct of_device_id sunplus_pwm_of_match[] = {
{ .compatible = "sunplus,sp7021-pwm", },
{}
};
MODULE_DEVICE_TABLE(of, sunplus_pwm_of_match);
static struct platform_driver sunplus_pwm_driver = {
.probe = sunplus_pwm_probe,
.driver = {
.name = "sunplus-pwm",
.of_match_table = sunplus_pwm_of_match,
},
};
module_platform_driver(sunplus_pwm_driver);
MODULE_DESCRIPTION("Sunplus SoC PWM Driver");
MODULE_AUTHOR("Hammer Hsieh <hammerh0314@gmail.com>");
MODULE_LICENSE("GPL");
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