pwm-stm32.c
/*
* Copyright (C) STMicroelectronics 2016
*
* Author: Gerald Baeza <gerald.baeza@st.com>
*
* License terms: GNU General Public License (GPL), version 2
*
* Inspired by timer-stm32.c from Maxime Coquelin
* pwm-atmel.c from Bo Shen
*/
#include <linux/mfd/stm32-timers.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#define CCMR_CHANNEL_SHIFT 8
#define CCMR_CHANNEL_MASK 0xFF
#define MAX_BREAKINPUT 2
struct stm32_pwm {
struct pwm_chip chip;
struct device *dev;
struct clk *clk;
struct regmap *regmap;
u32 max_arr;
bool have_complementary_output;
};
struct stm32_breakinput {
u32 index;
u32 level;
u32 filter;
};
static inline struct stm32_pwm *to_stm32_pwm_dev(struct pwm_chip *chip)
{
return container_of(chip, struct stm32_pwm, chip);
}
static u32 active_channels(struct stm32_pwm *dev)
{
u32 ccer;
regmap_read(dev->regmap, TIM_CCER, &ccer);
return ccer & TIM_CCER_CCXE;
}
static int write_ccrx(struct stm32_pwm *dev, int ch, u32 value)
{
switch (ch) {
case 0:
return regmap_write(dev->regmap, TIM_CCR1, value);
case 1:
return regmap_write(dev->regmap, TIM_CCR2, value);
case 2:
return regmap_write(dev->regmap, TIM_CCR3, value);
case 3:
return regmap_write(dev->regmap, TIM_CCR4, value);
}
return -EINVAL;
}
static int stm32_pwm_config(struct stm32_pwm *priv, int ch,
int duty_ns, int period_ns)
{
unsigned long long prd, div, dty;
unsigned int prescaler = 0;
u32 ccmr, mask, shift;
/* Period and prescaler values depends on clock rate */
div = (unsigned long long)clk_get_rate(priv->clk) * period_ns;
do_div(div, NSEC_PER_SEC);
prd = div;
while (div > priv->max_arr) {
prescaler++;
div = prd;
do_div(div, prescaler + 1);
}
prd = div;
if (prescaler > MAX_TIM_PSC)
return -EINVAL;
/*
* All channels share the same prescaler and counter so when two
* channels are active at the same time we can't change them
*/
if (active_channels(priv) & ~(1 << ch * 4)) {
u32 psc, arr;
regmap_read(priv->regmap, TIM_PSC, &psc);
regmap_read(priv->regmap, TIM_ARR, &arr);
if ((psc != prescaler) || (arr != prd - 1))
return -EBUSY;
}
regmap_write(priv->regmap, TIM_PSC, prescaler);
regmap_write(priv->regmap, TIM_ARR, prd - 1);
regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
/* Calculate the duty cycles */
dty = prd * duty_ns;
do_div(dty, period_ns);
write_ccrx(priv, ch, dty);
/* Configure output mode */
shift = (ch & 0x1) * CCMR_CHANNEL_SHIFT;
ccmr = (TIM_CCMR_PE | TIM_CCMR_M1) << shift;
mask = CCMR_CHANNEL_MASK << shift;
if (ch < 2)
regmap_update_bits(priv->regmap, TIM_CCMR1, mask, ccmr);
else
regmap_update_bits(priv->regmap, TIM_CCMR2, mask, ccmr);
regmap_update_bits(priv->regmap, TIM_BDTR,
TIM_BDTR_MOE | TIM_BDTR_AOE,
TIM_BDTR_MOE | TIM_BDTR_AOE);
return 0;
}
static int stm32_pwm_set_polarity(struct stm32_pwm *priv, int ch,
enum pwm_polarity polarity)
{
u32 mask;
mask = TIM_CCER_CC1P << (ch * 4);
if (priv->have_complementary_output)
mask |= TIM_CCER_CC1NP << (ch * 4);
regmap_update_bits(priv->regmap, TIM_CCER, mask,
polarity == PWM_POLARITY_NORMAL ? 0 : mask);
return 0;
}
static int stm32_pwm_enable(struct stm32_pwm *priv, int ch)
{
u32 mask;
int ret;
ret = clk_enable(priv->clk);
if (ret)
return ret;
/* Enable channel */
mask = TIM_CCER_CC1E << (ch * 4);
if (priv->have_complementary_output)
mask |= TIM_CCER_CC1NE << (ch * 4);
regmap_update_bits(priv->regmap, TIM_CCER, mask, mask);
/* Make sure that registers are updated */
regmap_update_bits(priv->regmap, TIM_EGR, TIM_EGR_UG, TIM_EGR_UG);
/* Enable controller */
regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, TIM_CR1_CEN);
return 0;
}
static void stm32_pwm_disable(struct stm32_pwm *priv, int ch)
{
u32 mask;
/* Disable channel */
mask = TIM_CCER_CC1E << (ch * 4);
if (priv->have_complementary_output)
mask |= TIM_CCER_CC1NE << (ch * 4);
regmap_update_bits(priv->regmap, TIM_CCER, mask, 0);
/* When all channels are disabled, we can disable the controller */
if (!active_channels(priv))
regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, 0);
clk_disable(priv->clk);
}
static int stm32_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_state *state)
{
bool enabled;
struct stm32_pwm *priv = to_stm32_pwm_dev(chip);
int ret;
enabled = pwm->state.enabled;
if (enabled && !state->enabled) {
stm32_pwm_disable(priv, pwm->hwpwm);
return 0;
}
if (state->polarity != pwm->state.polarity)
stm32_pwm_set_polarity(priv, pwm->hwpwm, state->polarity);
ret = stm32_pwm_config(priv, pwm->hwpwm,
state->duty_cycle, state->period);
if (ret)
return ret;
if (!enabled && state->enabled)
ret = stm32_pwm_enable(priv, pwm->hwpwm);
return ret;
}
static const struct pwm_ops stm32pwm_ops = {
.owner = THIS_MODULE,
.apply = stm32_pwm_apply,
};
static int stm32_pwm_set_breakinput(struct stm32_pwm *priv,
int index, int level, int filter)
{
u32 bke = (index == 0) ? TIM_BDTR_BKE : TIM_BDTR_BK2E;
int shift = (index == 0) ? TIM_BDTR_BKF_SHIFT : TIM_BDTR_BK2F_SHIFT;
u32 mask = (index == 0) ? TIM_BDTR_BKE | TIM_BDTR_BKP | TIM_BDTR_BKF
: TIM_BDTR_BK2E | TIM_BDTR_BK2P | TIM_BDTR_BK2F;
u32 bdtr = bke;
/*
* The both bits could be set since only one will be wrote
* due to mask value.
*/
if (level)
bdtr |= TIM_BDTR_BKP | TIM_BDTR_BK2P;
bdtr |= (filter & TIM_BDTR_BKF_MASK) << shift;
regmap_update_bits(priv->regmap, TIM_BDTR, mask, bdtr);
regmap_read(priv->regmap, TIM_BDTR, &bdtr);
return (bdtr & bke) ? 0 : -EINVAL;
}
static int stm32_pwm_apply_breakinputs(struct stm32_pwm *priv,
struct device_node *np)
{
struct stm32_breakinput breakinput[MAX_BREAKINPUT];
int nb, ret, i, array_size;
nb = of_property_count_elems_of_size(np, "st,breakinput",
sizeof(struct stm32_breakinput));
/*
* Because "st,breakinput" parameter is optional do not make probe
* failed if it doesn't exist.
*/
if (nb <= 0)
return 0;
if (nb > MAX_BREAKINPUT)
return -EINVAL;
array_size = nb * sizeof(struct stm32_breakinput) / sizeof(u32);
ret = of_property_read_u32_array(np, "st,breakinput",
(u32 *)breakinput, array_size);
if (ret)
return ret;
for (i = 0; i < nb && !ret; i++) {
ret = stm32_pwm_set_breakinput(priv,
breakinput[i].index,
breakinput[i].level,
breakinput[i].filter);
}
return ret;
}
static void stm32_pwm_detect_complementary(struct stm32_pwm *priv)
{
u32 ccer;
/*
* If complementary bit doesn't exist writing 1 will have no
* effect so we can detect it.
*/
regmap_update_bits(priv->regmap,
TIM_CCER, TIM_CCER_CC1NE, TIM_CCER_CC1NE);
regmap_read(priv->regmap, TIM_CCER, &ccer);
regmap_update_bits(priv->regmap, TIM_CCER, TIM_CCER_CC1NE, 0);
priv->have_complementary_output = (ccer != 0);
}
static int stm32_pwm_detect_channels(struct stm32_pwm *priv)
{
u32 ccer;
int npwm = 0;
/*
* If channels enable bits don't exist writing 1 will have no
* effect so we can detect and count them.
*/
regmap_update_bits(priv->regmap,
TIM_CCER, TIM_CCER_CCXE, TIM_CCER_CCXE);
regmap_read(priv->regmap, TIM_CCER, &ccer);
regmap_update_bits(priv->regmap, TIM_CCER, TIM_CCER_CCXE, 0);
if (ccer & TIM_CCER_CC1E)
npwm++;
if (ccer & TIM_CCER_CC2E)
npwm++;
if (ccer & TIM_CCER_CC3E)
npwm++;
if (ccer & TIM_CCER_CC4E)
npwm++;
return npwm;
}
static int stm32_pwm_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct device_node *np = dev->of_node;
struct stm32_timers *ddata = dev_get_drvdata(pdev->dev.parent);
struct stm32_pwm *priv;
int ret;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->regmap = ddata->regmap;
priv->clk = ddata->clk;
priv->max_arr = ddata->max_arr;
if (!priv->regmap || !priv->clk)
return -EINVAL;
ret = stm32_pwm_apply_breakinputs(priv, np);
if (ret)
return ret;
stm32_pwm_detect_complementary(priv);
priv->chip.base = -1;
priv->chip.dev = dev;
priv->chip.ops = &stm32pwm_ops;
priv->chip.npwm = stm32_pwm_detect_channels(priv);
ret = pwmchip_add(&priv->chip);
if (ret < 0)
return ret;
platform_set_drvdata(pdev, priv);
return 0;
}
static int stm32_pwm_remove(struct platform_device *pdev)
{
struct stm32_pwm *priv = platform_get_drvdata(pdev);
unsigned int i;
for (i = 0; i < priv->chip.npwm; i++)
pwm_disable(&priv->chip.pwms[i]);
pwmchip_remove(&priv->chip);
return 0;
}
static const struct of_device_id stm32_pwm_of_match[] = {
{ .compatible = "st,stm32-pwm", },
{ /* end node */ },
};
MODULE_DEVICE_TABLE(of, stm32_pwm_of_match);
static struct platform_driver stm32_pwm_driver = {
.probe = stm32_pwm_probe,
.remove = stm32_pwm_remove,
.driver = {
.name = "stm32-pwm",
.of_match_table = stm32_pwm_of_match,
},
};
module_platform_driver(stm32_pwm_driver);
MODULE_ALIAS("platform:stm32-pwm");
MODULE_DESCRIPTION("STMicroelectronics STM32 PWM driver");
MODULE_LICENSE("GPL v2");