/* * Intel Low Power Subsystem PWM controller driver * * Copyright (C) 2014, Intel Corporation * Author: Mika Westerberg * Author: Chew Kean Ho * Author: Chang Rebecca Swee Fun * Author: Chew Chiau Ee * Author: Alan Cox * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include #include #include #include #include #include #include #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 struct pwm_lpss_chip { struct pwm_chip chip; void __iomem *regs; const struct pwm_lpss_boardinfo *info; }; 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) { return (pwm_lpss_read(pwm) & PWM_SW_UPDATE) ? -EBUSY : 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) - 1; freq *= base_unit_range; base_unit = DIV_ROUND_CLOSEST_ULL(freq, c); 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 << PWM_BASE_UNIT_SHIFT); base_unit &= base_unit_range; ctrl |= (u32) base_unit << PWM_BASE_UNIT_SHIFT; ctrl |= on_time_div; pwm_lpss_write(pwm, ctrl); } 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_apply(struct pwm_chip *chip, struct pwm_device *pwm, struct pwm_state *state) { struct pwm_lpss_chip *lpwm = to_lpwm(chip); int ret; if (state->enabled) { if (!pwm_is_enabled(pwm)) { pm_runtime_get_sync(chip->dev); ret = pwm_lpss_is_updating(pwm); if (ret) { pm_runtime_put(chip->dev); return ret; } pwm_lpss_prepare(lpwm, pwm, state->duty_cycle, state->period); pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_SW_UPDATE); pwm_lpss_cond_enable(pwm, lpwm->info->bypass == false); ret = pwm_lpss_wait_for_update(pwm); if (ret) { pm_runtime_put(chip->dev); return ret; } pwm_lpss_cond_enable(pwm, lpwm->info->bypass == true); } else { ret = pwm_lpss_is_updating(pwm); if (ret) return ret; pwm_lpss_prepare(lpwm, pwm, state->duty_cycle, state->period); pwm_lpss_write(pwm, pwm_lpss_read(pwm) | PWM_SW_UPDATE); return pwm_lpss_wait_for_update(pwm); } } else if (pwm_is_enabled(pwm)) { pwm_lpss_write(pwm, pwm_lpss_read(pwm) & ~PWM_ENABLE); pm_runtime_put(chip->dev); } return 0; } static const struct pwm_ops pwm_lpss_ops = { .apply = pwm_lpss_apply, .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 ret; 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.base = -1; lpwm->chip.npwm = info->npwm; ret = pwmchip_add(&lpwm->chip); if (ret) { dev_err(dev, "failed to add PWM chip: %d\n", ret); return ERR_PTR(ret); } return lpwm; } EXPORT_SYMBOL_GPL(pwm_lpss_probe); int pwm_lpss_remove(struct pwm_lpss_chip *lpwm) { return pwmchip_remove(&lpwm->chip); } EXPORT_SYMBOL_GPL(pwm_lpss_remove); MODULE_DESCRIPTION("PWM driver for Intel LPSS"); MODULE_AUTHOR("Mika Westerberg "); MODULE_LICENSE("GPL v2");