// 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 pwm_chip chip; struct clk *clk; struct regmap *regmap; }; static inline struct stm32_pwm_lp *to_stm32_pwm_lp(struct pwm_chip *chip) { return container_of(chip, struct stm32_pwm_lp, 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_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 val, mask, cfgr, presc = 0; bool reenable; int ret; pwm_get_state(pwm, &cstate); reenable = !cstate.enabled; if (!state->enabled) { if (cstate.enabled) { /* 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(priv->chip.dev, "Can't reach %u ns\n", state->period); return -EINVAL; } prd = div; while (div > STM32_LPTIM_MAX_ARR) { presc++; if ((1 << presc) > STM32_LPTIM_MAX_PRESCALER) { dev_err(priv->chip.dev, "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); if (!cstate.enabled) { /* enable clock to drive PWM counter */ ret = clk_enable(priv->clk); if (ret) return ret; } ret = regmap_read(priv->regmap, STM32_LPTIM_CFGR, &cfgr); if (ret) goto err; if ((FIELD_GET(STM32_LPTIM_PRESC, cfgr) != presc) || (FIELD_GET(STM32_LPTIM_WAVPOL, cfgr) != state->polarity)) { val = FIELD_PREP(STM32_LPTIM_PRESC, presc); val |= FIELD_PREP(STM32_LPTIM_WAVPOL, state->polarity); mask = STM32_LPTIM_PRESC | 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; ret = regmap_write(priv->regmap, STM32_LPTIM_CMP, prd - (1 + dty)); if (ret) goto err; /* ensure CMP & ARR registers are properly written */ ret = regmap_read_poll_timeout(priv->regmap, STM32_LPTIM_ISR, val, (val & STM32_LPTIM_CMPOK_ARROK), 100, 1000); if (ret) { dev_err(priv->chip.dev, "ARR/CMP registers write issue\n"); goto err; } ret = regmap_write(priv->regmap, STM32_LPTIM_ICR, STM32_LPTIM_CMPOKCF_ARROKCF); if (ret) goto err; if (reenable) { /* Start LP timer in continuous mode */ ret = regmap_update_bits(priv->regmap, STM32_LPTIM_CR, STM32_LPTIM_CNTSTRT, 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 void 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; u64 tmp; regmap_read(priv->regmap, STM32_LPTIM_CR, &val); state->enabled = !!FIELD_GET(STM32_LPTIM_ENABLE, val); /* Keep PWM counter clock refcount in sync with PWM initial state */ if (state->enabled) clk_enable(priv->clk); regmap_read(priv->regmap, STM32_LPTIM_CFGR, &val); presc = FIELD_GET(STM32_LPTIM_PRESC, val); 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, STM32_LPTIM_CMP, &val); tmp = prd - val; tmp = (tmp << presc) * NSEC_PER_SEC; state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, rate); } static const struct pwm_ops stm32_pwm_lp_ops = { .owner = THIS_MODULE, .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; int ret; priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); if (!priv) return -ENOMEM; priv->regmap = ddata->regmap; priv->clk = ddata->clk; priv->chip.base = -1; priv->chip.dev = &pdev->dev; priv->chip.ops = &stm32_pwm_lp_ops; priv->chip.npwm = 1; priv->chip.of_xlate = of_pwm_xlate_with_flags; priv->chip.of_pwm_n_cells = 3; ret = pwmchip_add(&priv->chip); if (ret < 0) return ret; platform_set_drvdata(pdev, priv); return 0; } static int stm32_pwm_lp_remove(struct platform_device *pdev) { struct stm32_pwm_lp *priv = platform_get_drvdata(pdev); pwm_disable(&priv->chip.pwms[0]); return pwmchip_remove(&priv->chip); } static int __maybe_unused stm32_pwm_lp_suspend(struct device *dev) { struct stm32_pwm_lp *priv = dev_get_drvdata(dev); struct pwm_state state; pwm_get_state(&priv->chip.pwms[0], &state); if (state.enabled) { dev_err(dev, "The consumer didn't stop us (%s)\n", priv->chip.pwms[0].label); return -EBUSY; } return pinctrl_pm_select_sleep_state(dev); } static int __maybe_unused stm32_pwm_lp_resume(struct device *dev) { return pinctrl_pm_select_default_state(dev); } static 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, .remove = stm32_pwm_lp_remove, .driver = { .name = "stm32-pwm-lp", .of_match_table = of_match_ptr(stm32_pwm_lp_of_match), .pm = &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");