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linux-sg2042/drivers/pwm/pwm-stm32.c

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) STMicroelectronics 2016
*
* Author: Gerald Baeza <gerald.baeza@st.com>
*
* Inspired by timer-stm32.c from Maxime Coquelin
* pwm-atmel.c from Bo Shen
*/
#include <linux/bitfield.h>
#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 mutex lock; /* protect pwm config/enable */
struct clk *clk;
struct regmap *regmap;
u32 max_arr;
bool have_complementary_output;
u32 capture[4] ____cacheline_aligned; /* DMA'able buffer */
};
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;
}
#define TIM_CCER_CC12P (TIM_CCER_CC1P | TIM_CCER_CC2P)
#define TIM_CCER_CC12E (TIM_CCER_CC1E | TIM_CCER_CC2E)
#define TIM_CCER_CC34P (TIM_CCER_CC3P | TIM_CCER_CC4P)
#define TIM_CCER_CC34E (TIM_CCER_CC3E | TIM_CCER_CC4E)
/*
* Capture using PWM input mode:
* ___ ___
* TI[1, 2, 3 or 4]: ........._| |________|
* ^0 ^1 ^2
* . . .
* . . XXXXX
* . . XXXXX |
* . XXXXX . |
* XXXXX . . |
* COUNTER: ______XXXXX . . . |_XXX
* start^ . . . ^stop
* . . . .
* v v . v
* v
* CCR1/CCR3: tx..........t0...........t2
* CCR2/CCR4: tx..............t1.........
*
* DMA burst transfer: | |
* v v
* DMA buffer: { t0, tx } { t2, t1 }
* DMA done: ^
*
* 0: IC1/3 snapchot on rising edge: counter value -> CCR1/CCR3
* + DMA transfer CCR[1/3] & CCR[2/4] values (t0, tx: doesn't care)
* 1: IC2/4 snapchot on falling edge: counter value -> CCR2/CCR4
* 2: IC1/3 snapchot on rising edge: counter value -> CCR1/CCR3
* + DMA transfer CCR[1/3] & CCR[2/4] values (t2, t1)
*
* DMA done, compute:
* - Period = t2 - t0
* - Duty cycle = t1 - t0
*/
static int stm32_pwm_raw_capture(struct stm32_pwm *priv, struct pwm_device *pwm,
unsigned long tmo_ms, u32 *raw_prd,
u32 *raw_dty)
{
struct device *parent = priv->chip.dev->parent;
enum stm32_timers_dmas dma_id;
u32 ccen, ccr;
int ret;
/* Ensure registers have been updated, enable counter and capture */
regmap_update_bits(priv->regmap, TIM_EGR, TIM_EGR_UG, TIM_EGR_UG);
regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, TIM_CR1_CEN);
/* Use cc1 or cc3 DMA resp for PWM input channels 1 & 2 or 3 & 4 */
dma_id = pwm->hwpwm < 2 ? STM32_TIMERS_DMA_CH1 : STM32_TIMERS_DMA_CH3;
ccen = pwm->hwpwm < 2 ? TIM_CCER_CC12E : TIM_CCER_CC34E;
ccr = pwm->hwpwm < 2 ? TIM_CCR1 : TIM_CCR3;
regmap_update_bits(priv->regmap, TIM_CCER, ccen, ccen);
/*
* Timer DMA burst mode. Request 2 registers, 2 bursts, to get both
* CCR1 & CCR2 (or CCR3 & CCR4) on each capture event.
* We'll get two capture snapchots: { CCR1, CCR2 }, { CCR1, CCR2 }
* or { CCR3, CCR4 }, { CCR3, CCR4 }
*/
ret = stm32_timers_dma_burst_read(parent, priv->capture, dma_id, ccr, 2,
2, tmo_ms);
if (ret)
goto stop;
/* Period: t2 - t0 (take care of counter overflow) */
if (priv->capture[0] <= priv->capture[2])
*raw_prd = priv->capture[2] - priv->capture[0];
else
*raw_prd = priv->max_arr - priv->capture[0] + priv->capture[2];
/* Duty cycle capture requires at least two capture units */
if (pwm->chip->npwm < 2)
*raw_dty = 0;
else if (priv->capture[0] <= priv->capture[3])
*raw_dty = priv->capture[3] - priv->capture[0];
else
*raw_dty = priv->max_arr - priv->capture[0] + priv->capture[3];
if (*raw_dty > *raw_prd) {
/*
* Race beetween PWM input and DMA: it may happen
* falling edge triggers new capture on TI2/4 before DMA
* had a chance to read CCR2/4. It means capture[1]
* contains period + duty_cycle. So, subtract period.
*/
*raw_dty -= *raw_prd;
}
stop:
regmap_update_bits(priv->regmap, TIM_CCER, ccen, 0);
regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN, 0);
return ret;
}
static int stm32_pwm_capture(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_capture *result, unsigned long tmo_ms)
{
struct stm32_pwm *priv = to_stm32_pwm_dev(chip);
unsigned long long prd, div, dty;
unsigned long rate;
unsigned int psc = 0, icpsc, scale;
u32 raw_prd = 0, raw_dty = 0;
int ret = 0;
mutex_lock(&priv->lock);
if (active_channels(priv)) {
ret = -EBUSY;
goto unlock;
}
ret = clk_enable(priv->clk);
if (ret) {
dev_err(priv->chip.dev, "failed to enable counter clock\n");
goto unlock;
}
rate = clk_get_rate(priv->clk);
if (!rate) {
ret = -EINVAL;
goto clk_dis;
}
/* prescaler: fit timeout window provided by upper layer */
div = (unsigned long long)rate * (unsigned long long)tmo_ms;
do_div(div, MSEC_PER_SEC);
prd = div;
while ((div > priv->max_arr) && (psc < MAX_TIM_PSC)) {
psc++;
div = prd;
do_div(div, psc + 1);
}
regmap_write(priv->regmap, TIM_ARR, priv->max_arr);
regmap_write(priv->regmap, TIM_PSC, psc);
/* Map TI1 or TI2 PWM input to IC1 & IC2 (or TI3/4 to IC3 & IC4) */
regmap_update_bits(priv->regmap,
pwm->hwpwm < 2 ? TIM_CCMR1 : TIM_CCMR2,
TIM_CCMR_CC1S | TIM_CCMR_CC2S, pwm->hwpwm & 0x1 ?
TIM_CCMR_CC1S_TI2 | TIM_CCMR_CC2S_TI2 :
TIM_CCMR_CC1S_TI1 | TIM_CCMR_CC2S_TI1);
/* Capture period on IC1/3 rising edge, duty cycle on IC2/4 falling. */
regmap_update_bits(priv->regmap, TIM_CCER, pwm->hwpwm < 2 ?
TIM_CCER_CC12P : TIM_CCER_CC34P, pwm->hwpwm < 2 ?
TIM_CCER_CC2P : TIM_CCER_CC4P);
ret = stm32_pwm_raw_capture(priv, pwm, tmo_ms, &raw_prd, &raw_dty);
if (ret)
goto stop;
/*
* Got a capture. Try to improve accuracy at high rates:
* - decrease counter clock prescaler, scale up to max rate.
* - use input prescaler, capture once every /2 /4 or /8 edges.
*/
if (raw_prd) {
u32 max_arr = priv->max_arr - 0x1000; /* arbitrary margin */
scale = max_arr / min(max_arr, raw_prd);
} else {
scale = priv->max_arr; /* bellow resolution, use max scale */
}
if (psc && scale > 1) {
/* 2nd measure with new scale */
psc /= scale;
regmap_write(priv->regmap, TIM_PSC, psc);
ret = stm32_pwm_raw_capture(priv, pwm, tmo_ms, &raw_prd,
&raw_dty);
if (ret)
goto stop;
}
/* Compute intermediate period not to exceed timeout at low rates */
prd = (unsigned long long)raw_prd * (psc + 1) * NSEC_PER_SEC;
do_div(prd, rate);
for (icpsc = 0; icpsc < MAX_TIM_ICPSC ; icpsc++) {
/* input prescaler: also keep arbitrary margin */
if (raw_prd >= (priv->max_arr - 0x1000) >> (icpsc + 1))
break;
if (prd >= (tmo_ms * NSEC_PER_MSEC) >> (icpsc + 2))
break;
}
if (!icpsc)
goto done;
/* Last chance to improve period accuracy, using input prescaler */
regmap_update_bits(priv->regmap,
pwm->hwpwm < 2 ? TIM_CCMR1 : TIM_CCMR2,
TIM_CCMR_IC1PSC | TIM_CCMR_IC2PSC,
FIELD_PREP(TIM_CCMR_IC1PSC, icpsc) |
FIELD_PREP(TIM_CCMR_IC2PSC, icpsc));
ret = stm32_pwm_raw_capture(priv, pwm, tmo_ms, &raw_prd, &raw_dty);
if (ret)
goto stop;
if (raw_dty >= (raw_prd >> icpsc)) {
/*
* We may fall here using input prescaler, when input
* capture starts on high side (before falling edge).
* Example with icpsc to capture on each 4 events:
*
* start 1st capture 2nd capture
* v v v
* ___ _____ _____ _____ _____ ____
* TI1..4 |__| |__| |__| |__| |__|
* v v . . . . . v v
* icpsc1/3: . 0 . 1 . 2 . 3 . 0
* icpsc2/4: 0 1 2 3 0
* v v v v
* CCR1/3 ......t0..............................t2
* CCR2/4 ..t1..............................t1'...
* . . .
* Capture0: .<----------------------------->.
* Capture1: .<-------------------------->. .
* . . .
* Period: .<------> . .
* Low side: .<>.
*
* Result:
* - Period = Capture0 / icpsc
* - Duty = Period - Low side = Period - (Capture0 - Capture1)
*/
raw_dty = (raw_prd >> icpsc) - (raw_prd - raw_dty);
}
done:
prd = (unsigned long long)raw_prd * (psc + 1) * NSEC_PER_SEC;
result->period = DIV_ROUND_UP_ULL(prd, rate << icpsc);
dty = (unsigned long long)raw_dty * (psc + 1) * NSEC_PER_SEC;
result->duty_cycle = DIV_ROUND_UP_ULL(dty, rate);
stop:
regmap_write(priv->regmap, TIM_CCER, 0);
regmap_write(priv->regmap, pwm->hwpwm < 2 ? TIM_CCMR1 : TIM_CCMR2, 0);
regmap_write(priv->regmap, TIM_PSC, 0);
clk_dis:
clk_disable(priv->clk);
unlock:
mutex_unlock(&priv->lock);
return ret;
}
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 int stm32_pwm_apply_locked(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_state *state)
{
struct stm32_pwm *priv = to_stm32_pwm_dev(chip);
int ret;
/* protect common prescaler for all active channels */
mutex_lock(&priv->lock);
ret = stm32_pwm_apply(chip, pwm, state);
mutex_unlock(&priv->lock);
return ret;
}
static const struct pwm_ops stm32pwm_ops = {
.owner = THIS_MODULE,
.apply = stm32_pwm_apply_locked,
.capture = IS_ENABLED(CONFIG_DMA_ENGINE) ? stm32_pwm_capture : NULL,
};
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;
mutex_init(&priv->lock);
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");
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