pwm-jz4740.c
// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
* JZ4740 platform PWM support
*
* Limitations:
* - The .apply callback doesn't complete the currently running period before
* reconfiguring the hardware.
*/
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/kernel.h>
#include <linux/mfd/ingenic-tcu.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/regmap.h>
struct soc_info {
unsigned int num_pwms;
};
struct jz4740_pwm_chip {
struct pwm_chip chip;
struct regmap *map;
};
static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
{
return container_of(chip, struct jz4740_pwm_chip, chip);
}
static bool jz4740_pwm_can_use_chn(struct jz4740_pwm_chip *jz,
unsigned int channel)
{
/* Enable all TCU channels for PWM use by default except channels 0/1 */
u32 pwm_channels_mask = GENMASK(jz->chip.npwm - 1, 2);
device_property_read_u32(jz->chip.dev->parent,
"ingenic,pwm-channels-mask",
&pwm_channels_mask);
return !!(pwm_channels_mask & BIT(channel));
}
static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct jz4740_pwm_chip *jz = to_jz4740(chip);
struct clk *clk;
char name[16];
int err;
if (!jz4740_pwm_can_use_chn(jz, pwm->hwpwm))
return -EBUSY;
snprintf(name, sizeof(name), "timer%u", pwm->hwpwm);
clk = clk_get(chip->dev, name);
if (IS_ERR(clk))
return dev_err_probe(chip->dev, PTR_ERR(clk),
"Failed to get clock\n");
err = clk_prepare_enable(clk);
if (err < 0) {
clk_put(clk);
return err;
}
pwm_set_chip_data(pwm, clk);
return 0;
}
static void jz4740_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct clk *clk = pwm_get_chip_data(pwm);
clk_disable_unprepare(clk);
clk_put(clk);
}
static int jz4740_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct jz4740_pwm_chip *jz = to_jz4740(chip);
/* Enable PWM output */
regmap_update_bits(jz->map, TCU_REG_TCSRc(pwm->hwpwm),
TCU_TCSR_PWM_EN, TCU_TCSR_PWM_EN);
/* Start counter */
regmap_write(jz->map, TCU_REG_TESR, BIT(pwm->hwpwm));
return 0;
}
static void jz4740_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct jz4740_pwm_chip *jz = to_jz4740(chip);
/*
* Set duty > period. This trick allows the TCU channels in TCU2 mode to
* properly return to their init level.
*/
regmap_write(jz->map, TCU_REG_TDHRc(pwm->hwpwm), 0xffff);
regmap_write(jz->map, TCU_REG_TDFRc(pwm->hwpwm), 0x0);
/*
* Disable PWM output.
* In TCU2 mode (channel 1/2 on JZ4750+), this must be done before the
* counter is stopped, while in TCU1 mode the order does not matter.
*/
regmap_update_bits(jz->map, TCU_REG_TCSRc(pwm->hwpwm),
TCU_TCSR_PWM_EN, 0);
/* Stop counter */
regmap_write(jz->map, TCU_REG_TECR, BIT(pwm->hwpwm));
}
static int jz4740_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
const struct pwm_state *state)
{
struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip);
unsigned long long tmp = 0xffffull * NSEC_PER_SEC;
struct clk *clk = pwm_get_chip_data(pwm);
unsigned long period, duty;
long rate;
int err;
/*
* Limit the clock to a maximum rate that still gives us a period value
* which fits in 16 bits.
*/
do_div(tmp, state->period);
/*
* /!\ IMPORTANT NOTE:
* -------------------
* This code relies on the fact that clk_round_rate() will always round
* down, which is not a valid assumption given by the clk API, but only
* happens to be true with the clk drivers used for Ingenic SoCs.
*
* Right now, there is no alternative as the clk API does not have a
* round-down function (and won't have one for a while), but if it ever
* comes to light, a round-down function should be used instead.
*/
rate = clk_round_rate(clk, tmp);
if (rate < 0) {
dev_err(chip->dev, "Unable to round rate: %ld", rate);
return rate;
}
/* Calculate period value */
tmp = (unsigned long long)rate * state->period;
do_div(tmp, NSEC_PER_SEC);
period = tmp;
/* Calculate duty value */
tmp = (unsigned long long)rate * state->duty_cycle;
do_div(tmp, NSEC_PER_SEC);
duty = tmp;
if (duty >= period)
duty = period - 1;
jz4740_pwm_disable(chip, pwm);
err = clk_set_rate(clk, rate);
if (err) {
dev_err(chip->dev, "Unable to set rate: %d", err);
return err;
}
/* Reset counter to 0 */
regmap_write(jz4740->map, TCU_REG_TCNTc(pwm->hwpwm), 0);
/* Set duty */
regmap_write(jz4740->map, TCU_REG_TDHRc(pwm->hwpwm), duty);
/* Set period */
regmap_write(jz4740->map, TCU_REG_TDFRc(pwm->hwpwm), period);
/* Set abrupt shutdown */
regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
TCU_TCSR_PWM_SD, TCU_TCSR_PWM_SD);
/*
* Set polarity.
*
* The PWM starts in inactive state until the internal timer reaches the
* duty value, then becomes active until the timer reaches the period
* value. In theory, we should then use (period - duty) as the real duty
* value, as a high duty value would otherwise result in the PWM pin
* being inactive most of the time.
*
* Here, we don't do that, and instead invert the polarity of the PWM
* when it is active. This trick makes the PWM start with its active
* state instead of its inactive state.
*/
if ((state->polarity == PWM_POLARITY_NORMAL) ^ state->enabled)
regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
TCU_TCSR_PWM_INITL_HIGH, 0);
else
regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
TCU_TCSR_PWM_INITL_HIGH,
TCU_TCSR_PWM_INITL_HIGH);
if (state->enabled)
jz4740_pwm_enable(chip, pwm);
return 0;
}
static const struct pwm_ops jz4740_pwm_ops = {
.request = jz4740_pwm_request,
.free = jz4740_pwm_free,
.apply = jz4740_pwm_apply,
.owner = THIS_MODULE,
};
static int jz4740_pwm_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct jz4740_pwm_chip *jz4740;
const struct soc_info *info;
info = device_get_match_data(dev);
if (!info)
return -EINVAL;
jz4740 = devm_kzalloc(dev, sizeof(*jz4740), GFP_KERNEL);
if (!jz4740)
return -ENOMEM;
jz4740->map = device_node_to_regmap(dev->parent->of_node);
if (IS_ERR(jz4740->map)) {
dev_err(dev, "regmap not found: %ld\n", PTR_ERR(jz4740->map));
return PTR_ERR(jz4740->map);
}
jz4740->chip.dev = dev;
jz4740->chip.ops = &jz4740_pwm_ops;
jz4740->chip.npwm = info->num_pwms;
return devm_pwmchip_add(dev, &jz4740->chip);
}
static const struct soc_info __maybe_unused jz4740_soc_info = {
.num_pwms = 8,
};
static const struct soc_info __maybe_unused jz4725b_soc_info = {
.num_pwms = 6,
};
static const struct soc_info __maybe_unused x1000_soc_info = {
.num_pwms = 5,
};
#ifdef CONFIG_OF
static const struct of_device_id jz4740_pwm_dt_ids[] = {
{ .compatible = "ingenic,jz4740-pwm", .data = &jz4740_soc_info },
{ .compatible = "ingenic,jz4725b-pwm", .data = &jz4725b_soc_info },
{ .compatible = "ingenic,x1000-pwm", .data = &x1000_soc_info },
{},
};
MODULE_DEVICE_TABLE(of, jz4740_pwm_dt_ids);
#endif
static struct platform_driver jz4740_pwm_driver = {
.driver = {
.name = "jz4740-pwm",
.of_match_table = of_match_ptr(jz4740_pwm_dt_ids),
},
.probe = jz4740_pwm_probe,
};
module_platform_driver(jz4740_pwm_driver);
MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
MODULE_DESCRIPTION("Ingenic JZ4740 PWM driver");
MODULE_ALIAS("platform:jz4740-pwm");
MODULE_LICENSE("GPL");