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pwm-lpss.c
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pwm-lpss.c
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// SPDX-License-Identifier: GPL-2.0-only /* * Intel Low Power Subsystem PWM controller driver * * Copyright (C) 2014, Intel Corporation * Author: Mika Westerberg <mika.westerberg@linux.intel.com> * Author: Chew Kean Ho <kean.ho.chew@intel.com> * Author: Chang Rebecca Swee Fun <rebecca.swee.fun.chang@intel.com> * Author: Chew Chiau Ee <chiau.ee.chew@intel.com> * Author: Alan Cox <alan@linux.intel.com> */ #include <linux/delay.h> #include <linux/io.h> #include <linux/iopoll.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/pm_runtime.h> #include <linux/time.h> #include "pwm-lpss.h" #define PWM 0x00000000 #define PWM_ENABLE BIT(31) #define PWM_SW_UPDATE BIT(30) #define PWM_BASE_UNIT_SHIFT 8 #define PWM_ON_TIME_DIV_MASK 0x000000ff /* Size of each PWM register space if multiple */ #define PWM_SIZE 0x400 static inline struct pwm_lpss_chip *to_lpwm(struct pwm_chip *chip) { return container_of(chip, struct pwm_lpss_chip, chip); } static inline u32 pwm_lpss_read(const struct pwm_device *pwm) { struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip); return readl(lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM); } static inline void pwm_lpss_write(const struct pwm_device *pwm, u32 value) { struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip); writel(value, lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM); } static int pwm_lpss_wait_for_update(struct pwm_device *pwm) { struct pwm_lpss_chip *lpwm = to_lpwm(pwm->chip); const void __iomem *addr = lpwm->regs + pwm->hwpwm * PWM_SIZE + PWM; const unsigned int ms = 500 * USEC_PER_MSEC; u32 val; int err; /* * PWM Configuration register has SW_UPDATE bit that is set when a new * configuration is written to the register. The bit is automatically * cleared at the start of the next output cycle by the IP block. * * If one writes a new configuration to the register while it still has * the bit enabled, PWM may freeze. That is, while one can still write * to the register, it won't have an effect. Thus, we try to sleep long * enough that the bit gets cleared and make sure the bit is not * enabled while we update the configuration. */ err = readl_poll_timeout(addr, val, !(val & PWM_SW_UPDATE), 40, ms); if (err) dev_err(pwm->chip->dev, "PWM_SW_UPDATE was not cleared\n"); return err; } static inline int pwm_lpss_is_updating(struct pwm_device *pwm) { if (pwm_lpss_read(pwm) & PWM_SW_UPDATE) { dev_err(pwm->chip->dev, "PWM_SW_UPDATE is still set, skipping update\n"); return -EBUSY; } return 0; } static void pwm_lpss_prepare(struct pwm_lpss_chip *lpwm, struct pwm_device *pwm, int duty_ns, int period_ns) { unsigned long long on_time_div; unsigned long c = lpwm->info->clk_rate, base_unit_range; unsigned long long base_unit, freq = NSEC_PER_SEC; u32 ctrl; do_div(freq, period_ns); /* * The equation is: * base_unit = round(base_unit_range * freq / c) */ base_unit_range = BIT(lpwm->info->base_unit_bits); freq *= base_unit_range; base_unit = DIV_ROUND_CLOSEST_ULL(freq, c); /* base_unit must not be 0 and we also want to avoid overflowing it */ base_unit = clamp_val(base_unit, 1, base_unit_range - 1); on_time_div = 255ULL * duty_ns; do_div(on_time_div, period_ns); on_time_div = 255ULL - on_time_div; ctrl = pwm_lpss_read(pwm); ctrl &= ~PWM_ON_TIME_DIV_MASK; ctrl &= ~((base_unit_range - 1) << PWM_BASE_UNIT_SHIFT); ctrl |= (u32) base_unit << PWM_BASE_UNIT_SHIFT; ctrl |= on_time_div; pwm_lpss_write(pwm, ctrl); pwm_lpss_write(pwm, ctrl | PWM_SW_UPDATE); } static inline void pwm_lpss_cond_enable(struct pwm_device *pwm, bool cond) { if (cond) pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_ENABLE); } static int pwm_lpss_prepare_enable(struct pwm_lpss_chip *lpwm, struct pwm_device *pwm, const struct pwm_state *state) { int ret; ret = pwm_lpss_is_updating(pwm); if (ret) return ret; pwm_lpss_prepare(lpwm, pwm, state->duty_cycle, state->period); pwm_lpss_cond_enable(pwm, lpwm->info->bypass == false); ret = pwm_lpss_wait_for_update(pwm); if (ret) return ret; pwm_lpss_cond_enable(pwm, lpwm->info->bypass == true); return 0; } static int pwm_lpss_apply(struct pwm_chip *chip, struct pwm_device *pwm, const struct pwm_state *state) { struct pwm_lpss_chip *lpwm = to_lpwm(chip); int ret = 0; if (state->enabled) { if (!pwm_is_enabled(pwm)) { pm_runtime_get_sync(chip->dev); ret = pwm_lpss_prepare_enable(lpwm, pwm, state); if (ret) pm_runtime_put(chip->dev); } else { ret = pwm_lpss_prepare_enable(lpwm, pwm, state); } } else if (pwm_is_enabled(pwm)) { pwm_lpss_write(pwm, pwm_lpss_read(pwm) & ~PWM_ENABLE); pm_runtime_put(chip->dev); } return ret; } static void pwm_lpss_get_state(struct pwm_chip *chip, struct pwm_device *pwm, struct pwm_state *state) { struct pwm_lpss_chip *lpwm = to_lpwm(chip); unsigned long base_unit_range; unsigned long long base_unit, freq, on_time_div; u32 ctrl; pm_runtime_get_sync(chip->dev); base_unit_range = BIT(lpwm->info->base_unit_bits); ctrl = pwm_lpss_read(pwm); on_time_div = 255 - (ctrl & PWM_ON_TIME_DIV_MASK); base_unit = (ctrl >> PWM_BASE_UNIT_SHIFT) & (base_unit_range - 1); freq = base_unit * lpwm->info->clk_rate; do_div(freq, base_unit_range); if (freq == 0) state->period = NSEC_PER_SEC; else state->period = NSEC_PER_SEC / (unsigned long)freq; on_time_div *= state->period; do_div(on_time_div, 255); state->duty_cycle = on_time_div; state->polarity = PWM_POLARITY_NORMAL; state->enabled = !!(ctrl & PWM_ENABLE); pm_runtime_put(chip->dev); } static const struct pwm_ops pwm_lpss_ops = { .apply = pwm_lpss_apply, .get_state = pwm_lpss_get_state, .owner = THIS_MODULE, }; struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r, const struct pwm_lpss_boardinfo *info) { struct pwm_lpss_chip *lpwm; unsigned long c; int i, ret; u32 ctrl; if (WARN_ON(info->npwm > MAX_PWMS)) return ERR_PTR(-ENODEV); lpwm = devm_kzalloc(dev, sizeof(*lpwm), GFP_KERNEL); if (!lpwm) return ERR_PTR(-ENOMEM); lpwm->regs = devm_ioremap_resource(dev, r); if (IS_ERR(lpwm->regs)) return ERR_CAST(lpwm->regs); lpwm->info = info; c = lpwm->info->clk_rate; if (!c) return ERR_PTR(-EINVAL); lpwm->chip.dev = dev; lpwm->chip.ops = &pwm_lpss_ops; lpwm->chip.npwm = info->npwm; ret = devm_pwmchip_add(dev, &lpwm->chip); if (ret) { dev_err(dev, "failed to add PWM chip: %d\n", ret); return ERR_PTR(ret); } for (i = 0; i < lpwm->info->npwm; i++) { ctrl = pwm_lpss_read(&lpwm->chip.pwms[i]); if (ctrl & PWM_ENABLE) pm_runtime_get(dev); } return lpwm; } EXPORT_SYMBOL_GPL(pwm_lpss_probe); MODULE_DESCRIPTION("PWM driver for Intel LPSS"); MODULE_AUTHOR("Mika Westerberg <mika.westerberg@linux.intel.com>"); MODULE_LICENSE("GPL v2");
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