diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/pwm/pwm-stm32.c | 700 |
1 files changed, 700 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c new file mode 100644 index 0000000000..dd2ee5d9ca --- /dev/null +++ b/drivers/pwm/pwm-stm32.c @@ -0,0 +1,700 @@ +// 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/pinctrl/consumer.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_breakinput { + u32 index; + u32 level; + u32 filter; +}; + +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; + struct stm32_breakinput breakinputs[MAX_BREAKINPUT]; + unsigned int num_breakinputs; + u32 capture[4] ____cacheline_aligned; /* DMA'able buffer */ +}; + +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_set_bits(priv->regmap, TIM_EGR, TIM_EGR_UG); + regmap_set_bits(priv->regmap, TIM_CR1, 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_set_bits(priv->regmap, TIM_CCER, 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_clear_bits(priv->regmap, TIM_CCER, ccen); + regmap_clear_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN); + + 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); + + /* Reset input selector to its default input and disable slave mode */ + regmap_write(priv->regmap, TIM_TISEL, 0x0); + regmap_write(priv->regmap, TIM_SMCR, 0x0); + + /* 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_set_bits(priv->regmap, TIM_CR1, 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_set_bits(priv->regmap, TIM_BDTR, TIM_BDTR_MOE); + + 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_set_bits(priv->regmap, TIM_CCER, mask); + + /* Make sure that registers are updated */ + regmap_set_bits(priv->regmap, TIM_EGR, TIM_EGR_UG); + + /* Enable controller */ + regmap_set_bits(priv->regmap, TIM_CR1, 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_clear_bits(priv->regmap, TIM_CCER, mask); + + /* When all channels are disabled, we can disable the controller */ + if (!active_channels(priv)) + regmap_clear_bits(priv->regmap, TIM_CR1, TIM_CR1_CEN); + + clk_disable(priv->clk); +} + +static int stm32_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const 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, + const 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, + const struct stm32_breakinput *bi) +{ + u32 shift = TIM_BDTR_BKF_SHIFT(bi->index); + u32 bke = TIM_BDTR_BKE(bi->index); + u32 bkp = TIM_BDTR_BKP(bi->index); + u32 bkf = TIM_BDTR_BKF(bi->index); + u32 mask = bkf | bkp | bke; + u32 bdtr; + + bdtr = (bi->filter & TIM_BDTR_BKF_MASK) << shift | bke; + + if (bi->level) + bdtr |= bkp; + + 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) +{ + unsigned int i; + int ret; + + for (i = 0; i < priv->num_breakinputs; i++) { + ret = stm32_pwm_set_breakinput(priv, &priv->breakinputs[i]); + if (ret < 0) + return ret; + } + + return 0; +} + +static int stm32_pwm_probe_breakinputs(struct stm32_pwm *priv, + struct device_node *np) +{ + int nb, ret, array_size; + unsigned int i; + + 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; + + priv->num_breakinputs = nb; + array_size = nb * sizeof(struct stm32_breakinput) / sizeof(u32); + ret = of_property_read_u32_array(np, "st,breakinput", + (u32 *)priv->breakinputs, array_size); + if (ret) + return ret; + + for (i = 0; i < priv->num_breakinputs; i++) { + if (priv->breakinputs[i].index > 1 || + priv->breakinputs[i].level > 1 || + priv->breakinputs[i].filter > 15) + return -EINVAL; + } + + return stm32_pwm_apply_breakinputs(priv); +} + +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_set_bits(priv->regmap, TIM_CCER, TIM_CCER_CC1NE); + regmap_read(priv->regmap, TIM_CCER, &ccer); + regmap_clear_bits(priv->regmap, TIM_CCER, TIM_CCER_CC1NE); + + priv->have_complementary_output = (ccer != 0); +} + +static unsigned int stm32_pwm_detect_channels(struct stm32_pwm *priv, + unsigned int *num_enabled) +{ + u32 ccer, ccer_backup; + + /* + * If channels enable bits don't exist writing 1 will have no + * effect so we can detect and count them. + */ + regmap_read(priv->regmap, TIM_CCER, &ccer_backup); + regmap_set_bits(priv->regmap, TIM_CCER, TIM_CCER_CCXE); + regmap_read(priv->regmap, TIM_CCER, &ccer); + regmap_write(priv->regmap, TIM_CCER, ccer_backup); + + *num_enabled = hweight32(ccer_backup & TIM_CCER_CCXE); + + return hweight32(ccer & TIM_CCER_CCXE); +} + +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; + unsigned int num_enabled; + unsigned int i; + 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_probe_breakinputs(priv, np); + if (ret) + return ret; + + stm32_pwm_detect_complementary(priv); + + priv->chip.dev = dev; + priv->chip.ops = &stm32pwm_ops; + priv->chip.npwm = stm32_pwm_detect_channels(priv, &num_enabled); + + /* Initialize clock refcount to number of enabled PWM channels. */ + for (i = 0; i < num_enabled; i++) + clk_enable(priv->clk); + + ret = devm_pwmchip_add(dev, &priv->chip); + if (ret < 0) + return ret; + + platform_set_drvdata(pdev, priv); + + return 0; +} + +static int __maybe_unused stm32_pwm_suspend(struct device *dev) +{ + struct stm32_pwm *priv = dev_get_drvdata(dev); + unsigned int i; + u32 ccer, mask; + + /* Look for active channels */ + ccer = active_channels(priv); + + for (i = 0; i < priv->chip.npwm; i++) { + mask = TIM_CCER_CC1E << (i * 4); + if (ccer & mask) { + dev_err(dev, "PWM %u still in use by consumer %s\n", + i, priv->chip.pwms[i].label); + return -EBUSY; + } + } + + return pinctrl_pm_select_sleep_state(dev); +} + +static int __maybe_unused stm32_pwm_resume(struct device *dev) +{ + struct stm32_pwm *priv = dev_get_drvdata(dev); + int ret; + + ret = pinctrl_pm_select_default_state(dev); + if (ret) + return ret; + + /* restore breakinput registers that may have been lost in low power */ + return stm32_pwm_apply_breakinputs(priv); +} + +static SIMPLE_DEV_PM_OPS(stm32_pwm_pm_ops, stm32_pwm_suspend, stm32_pwm_resume); + +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, + .driver = { + .name = "stm32-pwm", + .of_match_table = stm32_pwm_of_match, + .pm = &stm32_pwm_pm_ops, + }, +}; +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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