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drivers/pwm/pwm-stm32.c
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// SPDX-License-Identifier: GPL-2.0 |
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/* * Copyright (C) STMicroelectronics 2016 * * Author: Gerald Baeza <gerald.baeza@st.com> * |
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* Inspired by timer-stm32.c from Maxime Coquelin * pwm-atmel.c from Bo Shen */ |
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#include <linux/bitfield.h> |
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#include <linux/mfd/stm32-timers.h> #include <linux/module.h> #include <linux/of.h> |
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#include <linux/pinctrl/consumer.h> |
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#include <linux/platform_device.h> #include <linux/pwm.h> #define CCMR_CHANNEL_SHIFT 8 #define CCMR_CHANNEL_MASK 0xFF #define MAX_BREAKINPUT 2 |
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struct stm32_breakinput { u32 index; u32 level; u32 filter; }; |
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struct stm32_pwm { struct pwm_chip chip; |
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struct mutex lock; /* protect pwm config/enable */ |
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struct clk *clk; struct regmap *regmap; u32 max_arr; bool have_complementary_output; |
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struct stm32_breakinput breakinputs[MAX_BREAKINPUT]; unsigned int num_breakinputs; |
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u32 capture[4] ____cacheline_aligned; /* DMA'able buffer */ |
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}; |
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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; } |
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#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; |
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unsigned int psc = 0, icpsc, scale; |
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u32 raw_prd = 0, raw_dty = 0; |
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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 "); 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; |
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/* * Got a capture. Try to improve accuracy at high rates: * - decrease counter clock prescaler, scale up to max rate. |
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* - use input prescaler, capture once every /2 /4 or /8 edges. |
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*/ 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; } |
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/* Compute intermediate period not to exceed timeout at low rates */ |
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prd = (unsigned long long)raw_prd * (psc + 1) * NSEC_PER_SEC; |
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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); |
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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; } |
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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); |
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regmap_update_bits(priv->regmap, TIM_BDTR, TIM_BDTR_MOE, TIM_BDTR_MOE); |
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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, |
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const struct pwm_state *state) |
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{ 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; } |
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static int stm32_pwm_apply_locked(struct pwm_chip *chip, struct pwm_device *pwm, |
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const struct pwm_state *state) |
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{ 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; } |
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static const struct pwm_ops stm32pwm_ops = { .owner = THIS_MODULE, |
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.apply = stm32_pwm_apply_locked, |
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.capture = IS_ENABLED(CONFIG_DMA_ENGINE) ? stm32_pwm_capture : NULL, |
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}; static int stm32_pwm_set_breakinput(struct stm32_pwm *priv, |
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const struct stm32_breakinput *bi) |
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{ |
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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); |
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u32 mask = bkf | bkp | bke; u32 bdtr; |
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bdtr = (bi->filter & TIM_BDTR_BKF_MASK) << shift | bke; |
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if (bi->level) |
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bdtr |= bkp; |
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regmap_update_bits(priv->regmap, TIM_BDTR, mask, bdtr); regmap_read(priv->regmap, TIM_BDTR, &bdtr); return (bdtr & bke) ? 0 : -EINVAL; } |
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static int stm32_pwm_apply_breakinputs(struct stm32_pwm *priv) { unsigned int i; int ret; for (i = 0; i < priv->num_breakinputs; i++) { |
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ret = stm32_pwm_set_breakinput(priv, &priv->breakinputs[i]); |
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if (ret < 0) return ret; } return 0; } static int stm32_pwm_probe_breakinputs(struct stm32_pwm *priv, |
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struct device_node *np) { |
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int nb, ret, array_size; |
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unsigned int i; |
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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; |
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priv->num_breakinputs = nb; |
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array_size = nb * sizeof(struct stm32_breakinput) / sizeof(u32); ret = of_property_read_u32_array(np, "st,breakinput", |
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(u32 *)priv->breakinputs, array_size); |
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if (ret) return ret; |
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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; } |
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return stm32_pwm_apply_breakinputs(priv); |
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} 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; |
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mutex_init(&priv->lock); |
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priv->regmap = ddata->regmap; priv->clk = ddata->clk; priv->max_arr = ddata->max_arr; |
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priv->chip.of_xlate = of_pwm_xlate_with_flags; priv->chip.of_pwm_n_cells = 3; |
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if (!priv->regmap || !priv->clk) return -EINVAL; |
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ret = stm32_pwm_probe_breakinputs(priv, np); |
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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; } |
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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 ", 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); |
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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, |
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.pm = &stm32_pwm_pm_ops, |
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}, }; module_platform_driver(stm32_pwm_driver); MODULE_ALIAS("platform:stm32-pwm"); MODULE_DESCRIPTION("STMicroelectronics STM32 PWM driver"); MODULE_LICENSE("GPL v2"); |