diff options
Diffstat (limited to 'drivers/pwm/pwm-stm32-lp.c')
| -rw-r--r-- | drivers/pwm/pwm-stm32-lp.c | 432 |
1 files changed, 432 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-stm32-lp.c b/drivers/pwm/pwm-stm32-lp.c new file mode 100644 index 000000000000..4789eafb8bac --- /dev/null +++ b/drivers/pwm/pwm-stm32-lp.c @@ -0,0 +1,432 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * STM32 Low-Power Timer PWM driver + * + * Copyright (C) STMicroelectronics 2017 + * + * Author: Gerald Baeza <gerald.baeza@st.com> + * + * Inspired by Gerald Baeza's pwm-stm32 driver + */ + +#include <linux/bitfield.h> +#include <linux/mfd/stm32-lptimer.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/pinctrl/consumer.h> +#include <linux/platform_device.h> +#include <linux/pwm.h> + +struct stm32_pwm_lp { + struct clk *clk; + struct regmap *regmap; + unsigned int num_cc_chans; +}; + +static inline struct stm32_pwm_lp *to_stm32_pwm_lp(struct pwm_chip *chip) +{ + return pwmchip_get_drvdata(chip); +} + +/* STM32 Low-Power Timer is preceded by a configurable power-of-2 prescaler */ +#define STM32_LPTIM_MAX_PRESCALER 128 + +static int stm32_pwm_lp_update_allowed(struct stm32_pwm_lp *priv, int channel) +{ + int ret; + u32 ccmr1; + unsigned long ccmr; + + /* Only one PWM on this LPTIMER: enable, prescaler and reload value can be changed */ + if (!priv->num_cc_chans) + return true; + + ret = regmap_read(priv->regmap, STM32_LPTIM_CCMR1, &ccmr1); + if (ret) + return ret; + ccmr = ccmr1 & (STM32_LPTIM_CC1E | STM32_LPTIM_CC2E); + + /* More than one channel enabled: enable, prescaler or ARR value can't be changed */ + if (bitmap_weight(&ccmr, sizeof(u32) * BITS_PER_BYTE) > 1) + return false; + + /* + * Only one channel is enabled (or none): check status on the other channel, to + * report if enable, prescaler or ARR value can be changed. + */ + if (channel) + return !(ccmr1 & STM32_LPTIM_CC1E); + else + return !(ccmr1 & STM32_LPTIM_CC2E); +} + +static int stm32_pwm_lp_compare_channel_apply(struct stm32_pwm_lp *priv, int channel, + bool enable, enum pwm_polarity polarity) +{ + u32 ccmr1, val, mask; + bool reenable; + int ret; + + /* No dedicated CC channel: nothing to do */ + if (!priv->num_cc_chans) + return 0; + + ret = regmap_read(priv->regmap, STM32_LPTIM_CCMR1, &ccmr1); + if (ret) + return ret; + + if (channel) { + /* Must disable CC channel (CCxE) to modify polarity (CCxP), then re-enable */ + reenable = (enable && FIELD_GET(STM32_LPTIM_CC2E, ccmr1)) && + (polarity != FIELD_GET(STM32_LPTIM_CC2P, ccmr1)); + + mask = STM32_LPTIM_CC2SEL | STM32_LPTIM_CC2E | STM32_LPTIM_CC2P; + val = FIELD_PREP(STM32_LPTIM_CC2P, polarity); + val |= FIELD_PREP(STM32_LPTIM_CC2E, enable); + } else { + reenable = (enable && FIELD_GET(STM32_LPTIM_CC1E, ccmr1)) && + (polarity != FIELD_GET(STM32_LPTIM_CC1P, ccmr1)); + + mask = STM32_LPTIM_CC1SEL | STM32_LPTIM_CC1E | STM32_LPTIM_CC1P; + val = FIELD_PREP(STM32_LPTIM_CC1P, polarity); + val |= FIELD_PREP(STM32_LPTIM_CC1E, enable); + } + + if (reenable) { + u32 cfgr, presc; + unsigned long rate; + unsigned int delay_us; + + ret = regmap_update_bits(priv->regmap, STM32_LPTIM_CCMR1, + channel ? STM32_LPTIM_CC2E : STM32_LPTIM_CC1E, 0); + if (ret) + return ret; + /* + * After a write to the LPTIM_CCMRx register, a new write operation can only be + * performed after a delay of at least (PRESC × 3) clock cycles + */ + ret = regmap_read(priv->regmap, STM32_LPTIM_CFGR, &cfgr); + if (ret) + return ret; + presc = FIELD_GET(STM32_LPTIM_PRESC, cfgr); + rate = clk_get_rate(priv->clk) >> presc; + if (!rate) + return -EINVAL; + delay_us = 3 * DIV_ROUND_UP(USEC_PER_SEC, rate); + usleep_range(delay_us, delay_us * 2); + } + + return regmap_update_bits(priv->regmap, STM32_LPTIM_CCMR1, mask, val); +} + +static int stm32_pwm_lp_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) +{ + struct stm32_pwm_lp *priv = to_stm32_pwm_lp(chip); + unsigned long long prd, div, dty; + struct pwm_state cstate; + u32 arr, val, mask, cfgr, presc = 0; + bool reenable; + int ret; + + pwm_get_state(pwm, &cstate); + reenable = !cstate.enabled; + + if (!state->enabled) { + if (cstate.enabled) { + /* Disable CC channel if any */ + ret = stm32_pwm_lp_compare_channel_apply(priv, pwm->hwpwm, false, + state->polarity); + if (ret) + return ret; + ret = regmap_write(priv->regmap, pwm->hwpwm ? + STM32_LPTIM_CCR2 : STM32_LPTIM_CMP, 0); + if (ret) + return ret; + + /* Check if the timer can be disabled */ + ret = stm32_pwm_lp_update_allowed(priv, pwm->hwpwm); + if (ret < 0) + return ret; + + if (ret) { + /* Disable LP timer */ + ret = regmap_write(priv->regmap, STM32_LPTIM_CR, 0); + if (ret) + return ret; + } + + /* disable clock to PWM counter */ + clk_disable(priv->clk); + } + return 0; + } + + /* Calculate the period and prescaler value */ + div = (unsigned long long)clk_get_rate(priv->clk) * state->period; + do_div(div, NSEC_PER_SEC); + if (!div) { + /* Clock is too slow to achieve requested period. */ + dev_dbg(pwmchip_parent(chip), "Can't reach %llu ns\n", state->period); + return -EINVAL; + } + + prd = div; + while (div > STM32_LPTIM_MAX_ARR) { + presc++; + if ((1 << presc) > STM32_LPTIM_MAX_PRESCALER) { + dev_err(pwmchip_parent(chip), "max prescaler exceeded\n"); + return -EINVAL; + } + div = prd >> presc; + } + prd = div; + + /* Calculate the duty cycle */ + dty = prd * state->duty_cycle; + do_div(dty, state->period); + + ret = regmap_read(priv->regmap, STM32_LPTIM_CFGR, &cfgr); + if (ret) + return ret; + + /* + * When there are several channels, they share the same prescaler and reload value. + * Check if this can be changed, or the values are the same for all channels. + */ + if (!stm32_pwm_lp_update_allowed(priv, pwm->hwpwm)) { + ret = regmap_read(priv->regmap, STM32_LPTIM_ARR, &arr); + if (ret) + return ret; + + if ((FIELD_GET(STM32_LPTIM_PRESC, cfgr) != presc) || (arr != prd - 1)) + return -EBUSY; + } + + if (!cstate.enabled) { + /* enable clock to drive PWM counter */ + ret = clk_enable(priv->clk); + if (ret) + return ret; + } + + if ((FIELD_GET(STM32_LPTIM_PRESC, cfgr) != presc) || + ((FIELD_GET(STM32_LPTIM_WAVPOL, cfgr) != state->polarity) && !priv->num_cc_chans)) { + val = FIELD_PREP(STM32_LPTIM_PRESC, presc); + mask = STM32_LPTIM_PRESC; + + if (!priv->num_cc_chans) { + /* + * WAVPOL bit is only available when no capature compare channel is used, + * e.g. on LPTIMER instances that have only one output channel. CCMR1 is + * used otherwise. + */ + val |= FIELD_PREP(STM32_LPTIM_WAVPOL, state->polarity); + mask |= STM32_LPTIM_WAVPOL; + } + + /* Must disable LP timer to modify CFGR */ + reenable = true; + ret = regmap_write(priv->regmap, STM32_LPTIM_CR, 0); + if (ret) + goto err; + + ret = regmap_update_bits(priv->regmap, STM32_LPTIM_CFGR, mask, + val); + if (ret) + goto err; + } + + if (reenable) { + /* Must (re)enable LP timer to modify CMP & ARR */ + ret = regmap_write(priv->regmap, STM32_LPTIM_CR, + STM32_LPTIM_ENABLE); + if (ret) + goto err; + } + + ret = regmap_write(priv->regmap, STM32_LPTIM_ARR, prd - 1); + if (ret) + goto err; + + /* Write CMP/CCRx register and ensure it's been properly written */ + ret = regmap_write(priv->regmap, pwm->hwpwm ? STM32_LPTIM_CCR2 : STM32_LPTIM_CMP, + prd - (1 + dty)); + if (ret) + goto err; + + /* ensure ARR and CMP/CCRx registers are properly written */ + ret = regmap_read_poll_timeout(priv->regmap, STM32_LPTIM_ISR, val, pwm->hwpwm ? + (val & STM32_LPTIM_CMP2_ARROK) == STM32_LPTIM_CMP2_ARROK : + (val & STM32_LPTIM_CMPOK_ARROK) == STM32_LPTIM_CMPOK_ARROK, + 100, 1000); + if (ret) { + dev_err(pwmchip_parent(chip), "ARR/CMP registers write issue\n"); + goto err; + } + ret = regmap_write(priv->regmap, STM32_LPTIM_ICR, pwm->hwpwm ? + STM32_LPTIM_CMP2OKCF_ARROKCF : STM32_LPTIM_CMPOKCF_ARROKCF); + if (ret) + goto err; + + ret = stm32_pwm_lp_compare_channel_apply(priv, pwm->hwpwm, true, state->polarity); + if (ret) + goto err; + + if (reenable) { + /* Start LP timer in continuous mode */ + ret = regmap_set_bits(priv->regmap, STM32_LPTIM_CR, + STM32_LPTIM_CNTSTRT); + if (ret) { + regmap_write(priv->regmap, STM32_LPTIM_CR, 0); + goto err; + } + } + + return 0; +err: + if (!cstate.enabled) + clk_disable(priv->clk); + + return ret; +} + +static int stm32_pwm_lp_get_state(struct pwm_chip *chip, + struct pwm_device *pwm, + struct pwm_state *state) +{ + struct stm32_pwm_lp *priv = to_stm32_pwm_lp(chip); + unsigned long rate = clk_get_rate(priv->clk); + u32 val, presc, prd, ccmr1; + bool enabled; + u64 tmp; + + regmap_read(priv->regmap, STM32_LPTIM_CR, &val); + enabled = !!FIELD_GET(STM32_LPTIM_ENABLE, val); + if (priv->num_cc_chans) { + /* There's a CC chan, need to also check if it's enabled */ + regmap_read(priv->regmap, STM32_LPTIM_CCMR1, &ccmr1); + if (pwm->hwpwm) + enabled &= !!FIELD_GET(STM32_LPTIM_CC2E, ccmr1); + else + enabled &= !!FIELD_GET(STM32_LPTIM_CC1E, ccmr1); + } + state->enabled = enabled; + + /* Keep PWM counter clock refcount in sync with PWM initial state */ + if (state->enabled) { + int ret = clk_enable(priv->clk); + + if (ret) + return ret; + } + + regmap_read(priv->regmap, STM32_LPTIM_CFGR, &val); + presc = FIELD_GET(STM32_LPTIM_PRESC, val); + if (priv->num_cc_chans) { + if (pwm->hwpwm) + state->polarity = FIELD_GET(STM32_LPTIM_CC2P, ccmr1); + else + state->polarity = FIELD_GET(STM32_LPTIM_CC1P, ccmr1); + } else { + state->polarity = FIELD_GET(STM32_LPTIM_WAVPOL, val); + } + + regmap_read(priv->regmap, STM32_LPTIM_ARR, &prd); + tmp = prd + 1; + tmp = (tmp << presc) * NSEC_PER_SEC; + state->period = DIV_ROUND_CLOSEST_ULL(tmp, rate); + + regmap_read(priv->regmap, pwm->hwpwm ? STM32_LPTIM_CCR2 : STM32_LPTIM_CMP, &val); + tmp = prd - val; + tmp = (tmp << presc) * NSEC_PER_SEC; + state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, rate); + + return 0; +} + +static const struct pwm_ops stm32_pwm_lp_ops = { + .apply = stm32_pwm_lp_apply, + .get_state = stm32_pwm_lp_get_state, +}; + +static int stm32_pwm_lp_probe(struct platform_device *pdev) +{ + struct stm32_lptimer *ddata = dev_get_drvdata(pdev->dev.parent); + struct stm32_pwm_lp *priv; + struct pwm_chip *chip; + unsigned int npwm; + int ret; + + if (!ddata->num_cc_chans) { + /* No dedicated CC channel, so there's only one PWM channel */ + npwm = 1; + } else { + /* There are dedicated CC channels, each with one PWM output */ + npwm = ddata->num_cc_chans; + } + + chip = devm_pwmchip_alloc(&pdev->dev, npwm, sizeof(*priv)); + if (IS_ERR(chip)) + return PTR_ERR(chip); + priv = to_stm32_pwm_lp(chip); + + priv->regmap = ddata->regmap; + priv->clk = ddata->clk; + priv->num_cc_chans = ddata->num_cc_chans; + chip->ops = &stm32_pwm_lp_ops; + + ret = devm_pwmchip_add(&pdev->dev, chip); + if (ret < 0) + return ret; + + platform_set_drvdata(pdev, chip); + + return 0; +} + +static int stm32_pwm_lp_suspend(struct device *dev) +{ + struct pwm_chip *chip = dev_get_drvdata(dev); + struct pwm_state state; + unsigned int i; + + for (i = 0; i < chip->npwm; i++) { + pwm_get_state(&chip->pwms[i], &state); + if (state.enabled) { + dev_err(dev, "The consumer didn't stop us (%s)\n", + chip->pwms[i].label); + return -EBUSY; + } + } + + return pinctrl_pm_select_sleep_state(dev); +} + +static int stm32_pwm_lp_resume(struct device *dev) +{ + return pinctrl_pm_select_default_state(dev); +} + +static DEFINE_SIMPLE_DEV_PM_OPS(stm32_pwm_lp_pm_ops, stm32_pwm_lp_suspend, + stm32_pwm_lp_resume); + +static const struct of_device_id stm32_pwm_lp_of_match[] = { + { .compatible = "st,stm32-pwm-lp", }, + {}, +}; +MODULE_DEVICE_TABLE(of, stm32_pwm_lp_of_match); + +static struct platform_driver stm32_pwm_lp_driver = { + .probe = stm32_pwm_lp_probe, + .driver = { + .name = "stm32-pwm-lp", + .of_match_table = stm32_pwm_lp_of_match, + .pm = pm_ptr(&stm32_pwm_lp_pm_ops), + }, +}; +module_platform_driver(stm32_pwm_lp_driver); + +MODULE_ALIAS("platform:stm32-pwm-lp"); +MODULE_DESCRIPTION("STMicroelectronics STM32 PWM LP driver"); +MODULE_LICENSE("GPL v2"); |