On Thu, Feb 21, 2019 at 02:41:41PM +0530, Yash Shah wrote: > Adds a PWM driver for PWM chip present in SiFive's HiFive Unleashed SoC. > > Signed-off-by: Wesley W. Terpstra <wesley@xxxxxxxxxx> > [Atish: Various fixes and code cleanup] > Signed-off-by: Atish Patra <atish.patra@xxxxxxx> > Signed-off-by: Yash Shah <yash.shah@xxxxxxxxxx> > --- > drivers/pwm/Kconfig | 11 ++ > drivers/pwm/Makefile | 1 + > drivers/pwm/pwm-sifive.c | 346 +++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 358 insertions(+) > create mode 100644 drivers/pwm/pwm-sifive.c > > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig > index a8f47df..4a61d1a 100644 > --- a/drivers/pwm/Kconfig > +++ b/drivers/pwm/Kconfig > @@ -380,6 +380,17 @@ config PWM_SAMSUNG > To compile this driver as a module, choose M here: the module > will be called pwm-samsung. > > +config PWM_SIFIVE > + tristate "SiFive PWM support" > + depends on OF > + depends on COMMON_CLK > + depends on RISCV || COMPILE_TEST > + help > + Generic PWM framework driver for SiFive SoCs. > + > + To compile this driver as a module, choose M here: the module > + will be called pwm-sifive. > + > config PWM_SPEAR > tristate "STMicroelectronics SPEAr PWM support" > depends on PLAT_SPEAR > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile > index 9c676a0..30089ca 100644 > --- a/drivers/pwm/Makefile > +++ b/drivers/pwm/Makefile > @@ -37,6 +37,7 @@ obj-$(CONFIG_PWM_RCAR) += pwm-rcar.o > obj-$(CONFIG_PWM_RENESAS_TPU) += pwm-renesas-tpu.o > obj-$(CONFIG_PWM_ROCKCHIP) += pwm-rockchip.o > obj-$(CONFIG_PWM_SAMSUNG) += pwm-samsung.o > +obj-$(CONFIG_PWM_SIFIVE) += pwm-sifive.o > obj-$(CONFIG_PWM_SPEAR) += pwm-spear.o > obj-$(CONFIG_PWM_STI) += pwm-sti.o > obj-$(CONFIG_PWM_STM32) += pwm-stm32.o > diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c > new file mode 100644 > index 0000000..8f29283d > --- /dev/null > +++ b/drivers/pwm/pwm-sifive.c > @@ -0,0 +1,346 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * Copyright (C) 2017-2018 SiFive > + * For SiFive's PWM IP block documentation please refer Chapter 14 of > + * Reference Manual : https://static.dev.sifive.com/FU540-C000-v1.0.pdf > + * > + * Limitations: > + * - When changing both duty cycle and period, we cannot prevent in > + * software that the output might produce a period with mixed > + * settings (new period length and old duty cycle). > + * - The hardware cannot generate a 100% duty cycle. > + * - The hardware generaets only inverted output. s/generaets/generates/ > + */ > +#include <linux/clk.h> > +#include <linux/io.h> > +#include <linux/module.h> > +#include <linux/platform_device.h> > +#include <linux/pwm.h> > +#include <linux/slab.h> > + > +/* Register offsets */ > +#define PWM_SIFIVE_PWMCFG 0x0 > +#define PWM_SIFIVE_PWMCOUNT 0x8 > +#define PWM_SIFIVE_PWMS 0x10 > +#define PWM_SIFIVE_PWMCMP0 0x20 > + > +/* PWMCFG fields */ > +#define PWM_SIFIVE_PWMCFG_SCALE 0 > +#define PWM_SIFIVE_PWMCFG_STICKY 8 > +#define PWM_SIFIVE_PWMCFG_ZERO_CMP 9 > +#define PWM_SIFIVE_PWMCFG_DEGLITCH 10 > +#define PWM_SIFIVE_PWMCFG_EN_ALWAYS BIT(12) > +#define PWM_SIFIVE_PWMCFG_EN_ONCE 13 > +#define PWM_SIFIVE_PWMCFG_CENTER 16 > +#define PWM_SIFIVE_PWMCFG_GANG 24 > +#define PWM_SIFIVE_PWMCFG_IP 28 > + > +/* PWM_SIFIVE_SIZE_PWMCMP is used to calculate offset for pwmcmpX registers */ > +#define PWM_SIFIVE_SIZE_PWMCMP 4 > +#define PWM_SIFIVE_CMPWIDTH 16 > + > +struct pwm_sifive_ddata { > + struct pwm_chip chip; > + struct mutex lock; /* lock to protect user_count and active_user */ > + struct notifier_block notifier; > + struct clk *clk; > + void __iomem *regs; > + unsigned int real_period; > + int user_count; > + int active_user; > +}; > + > +static inline > +struct pwm_sifive_ddata *pwm_sifive_chip_to_ddata(struct pwm_chip *c) > +{ > + return container_of(c, struct pwm_sifive_ddata, chip); > +} > + > +static int pwm_sifive_request(struct pwm_chip *chip, struct pwm_device *dev) > +{ > + struct pwm_sifive_ddata *pwm = pwm_sifive_chip_to_ddata(chip); > + > + mutex_lock(&pwm->lock); > + pwm->user_count++; > + mutex_unlock(&pwm->lock); > + > + return 0; > +} > + > +static void pwm_sifive_free(struct pwm_chip *chip, struct pwm_device *dev) > +{ > + struct pwm_sifive_ddata *pwm = pwm_sifive_chip_to_ddata(chip); > + > + mutex_lock(&pwm->lock); > + pwm->user_count--; > + mutex_unlock(&pwm->lock); > +} > + > +static void pwm_sifive_update_clock(struct pwm_sifive_ddata *pwm, > + unsigned long rate) > +{ > + u32 val; > + unsigned long num; > + /* (1 << (PWM_SIFIVE_CMPWIDTH+scale)) * 10^9/rate = real_period */ > + unsigned long scale_pow = > + div64_ul(pwm->real_period * (u64)rate, NSEC_PER_SEC); > + int scale = clamp(ilog2(scale_pow) - PWM_SIFIVE_CMPWIDTH, 0, 0xf); > + > + val = PWM_SIFIVE_PWMCFG_EN_ALWAYS | (scale << PWM_SIFIVE_PWMCFG_SCALE); > + writel(val, pwm->regs + PWM_SIFIVE_PWMCFG); > + > + /* As scale <= 15 the shift operation cannot overflow. */ > + num = 1000000000ULL << (PWM_SIFIVE_CMPWIDTH + scale); Huh, num is only an unsigned long, so you're loosing some bits here. > + pwm->real_period = div64_ul(num, rate); > + dev_dbg(pwm->chip.dev, "New real_period = %u ns\n", pwm->real_period); > +} > + > +static void pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *dev, > + struct pwm_state *state) > +{ > + struct pwm_sifive_ddata *pwm = pwm_sifive_chip_to_ddata(chip); > + u32 duty, val; > + unsigned long num; This should also be unsigned long long. > + duty = readl(pwm->regs + PWM_SIFIVE_PWMCMP0 + > + dev->hwpwm * PWM_SIFIVE_SIZE_PWMCMP); > + > + val = readl(pwm->regs + PWM_SIFIVE_PWMCFG); > + state->enabled = duty > 0; > + > + val &= 0x0F; > + num = 1000000000ULL << (PWM_SIFIVE_CMPWIDTH + val); > + pwm->real_period = div64_ul(num, clk_get_rate(pwm->clk)); clk_get_rate must only be called if the clock is enabled. > + state->period = pwm->real_period; > + state->duty_cycle = > + (u64)duty * pwm->real_period >> PWM_SIFIVE_CMPWIDTH; > + state->polarity = PWM_POLARITY_INVERSED; > +} > + > +static int pwm_sifive_enable(struct pwm_chip *chip, bool enable) > +{ > + struct pwm_sifive_ddata *pwm = pwm_sifive_chip_to_ddata(chip); > + int val, ret; > + > + if (enable) { > + ret = clk_enable(pwm->clk); > + if (ret) { > + dev_err(pwm->chip.dev, "Enable clk failed:%d\n", ret); > + return ret; > + } > + } > + > + val = readl(pwm->regs + PWM_SIFIVE_PWMCFG); > + > + if (enable) > + val |= PWM_SIFIVE_PWMCFG_EN_ALWAYS; > + else > + val &= ~PWM_SIFIVE_PWMCFG_EN_ALWAYS; > + > + writel(val, pwm->regs + PWM_SIFIVE_PWMCFG); > + > + if (!enable) > + clk_disable(pwm->clk); This might come too early as after clearing PWM_SIFIVE_PWMCFG_EN_ALWAYS the period has to finish first. > + return 0; > +} > + > +static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *dev, > + struct pwm_state *state) > +{ > + struct pwm_sifive_ddata *pwm = pwm_sifive_chip_to_ddata(chip); > + unsigned int duty_cycle, x; > + u32 frac; > + struct pwm_state cur_state; > + bool enabled; > + int ret; > + unsigned long num; > + > + pwm_get_state(dev, &cur_state); > + enabled = cur_state.enabled; > + > + if (state->polarity != PWM_POLARITY_INVERSED) > + return -EINVAL; > + > + if (state->period != cur_state.period) { > + mutex_lock(&pwm->lock); This lock is too late. You need to protect pwm_get_state() already. > + if (pwm->user_count != 1) { > + mutex_unlock(&pwm->lock); > + return -EINVAL; > + } > + pwm->real_period = state->period; > + pwm_sifive_update_clock(pwm, clk_get_rate(pwm->clk)); > + mutex_unlock(&pwm->lock); This is also wrong. > + } > + > + duty_cycle = state->duty_cycle; > + if (!state->enabled) > + duty_cycle = 0; > + > + x = 1U << PWM_SIFIVE_CMPWIDTH; > + num = (u64)duty_cycle * x + x / 2; > + frac = div_u64(num, state->period); > + /* The hardware cannot generate a 100% duty cycle */ > + frac = min(frac, x - 1); > + > + writel(frac, pwm->regs + PWM_SIFIVE_PWMCMP0 + > + dev->hwpwm * PWM_SIFIVE_SIZE_PWMCMP); > + > + if (!state->enabled && enabled) { > + mutex_lock(&pwm->lock); > + if (pwm->active_user == 1) { You count in .active_user something that clk_enable/clk_disable could already do for you. (Just keep PWM_SIFIVE_PWMCFG_EN_ALWAYS set, the generated wave forms are identical apart from the first enable taking more time without tracking active_user) > + ret = pwm_sifive_enable(chip, false); > + if (ret) { > + mutex_unlock(&pwm->lock); > + return ret; > + } > + } > + pwm->active_user--; > + mutex_unlock(&pwm->lock); > + enabled = false; > + } > + > + if (state->enabled != enabled) { I think using if (state->enabled && !enabled) { is equivalent but clearer. > + mutex_lock(&pwm->lock); > + if (pwm->active_user == 0) { > + ret = pwm_sifive_enable(chip, state->enabled); > + if (ret) { > + mutex_unlock(&pwm->lock); > + return ret; > + } > + } > + pwm->active_user++; > + mutex_unlock(&pwm->lock); > + } > + > + return 0; > +} > + > +static const struct pwm_ops pwm_sifive_ops = { > + .request = pwm_sifive_request, > + .free = pwm_sifive_free, > + .get_state = pwm_sifive_get_state, > + .apply = pwm_sifive_apply, > + .owner = THIS_MODULE, > +}; > + > +static int pwm_sifive_clock_notifier(struct notifier_block *nb, > + unsigned long event, void *data) > +{ > + struct clk_notifier_data *ndata = data; > + struct pwm_sifive_ddata *pwm = > + container_of(nb, struct pwm_sifive_ddata, notifier); > + > + if (event == POST_RATE_CHANGE) > + pwm_sifive_update_clock(pwm, ndata->new_rate); > + > + return NOTIFY_OK; > +} > + > +static int pwm_sifive_probe(struct platform_device *pdev) > +{ > + struct device *dev = &pdev->dev; > + struct pwm_sifive_ddata *pwm; > + struct pwm_chip *chip; > + struct resource *res; > + int ret; > + > + pwm = devm_kzalloc(dev, sizeof(*pwm), GFP_KERNEL); > + if (!pwm) > + return -ENOMEM; > + > + mutex_init(&pwm->lock); > + chip = &pwm->chip; > + chip->dev = dev; > + chip->ops = &pwm_sifive_ops; > + chip->of_pwm_n_cells = 3; > + chip->base = -1; > + chip->npwm = 4; > + > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); > + pwm->regs = devm_ioremap_resource(dev, res); > + if (IS_ERR(pwm->regs)) { > + dev_err(dev, "Unable to map IO resources\n"); > + return PTR_ERR(pwm->regs); > + } > + > + pwm->clk = devm_clk_get(dev, NULL); > + if (IS_ERR(pwm->clk)) { > + if (PTR_ERR(pwm->clk) != -EPROBE_DEFER) > + dev_err(dev, "Unable to find controller clock\n"); > + return PTR_ERR(pwm->clk); > + } > + > + ret = clk_prepare_enable(pwm->clk); > + if (ret) { > + dev_err(dev, "failed to enable clock for pwm: %d\n", ret); > + return ret; > + } > + > + /* Watch for changes to underlying clock frequency */ > + pwm->notifier.notifier_call = pwm_sifive_clock_notifier; > + ret = clk_notifier_register(pwm->clk, &pwm->notifier); > + if (ret) { > + dev_err(dev, "failed to register clock notifier: %d\n", ret); > + goto disable_clk; > + } > + > + ret = pwmchip_add(chip); > + if (ret < 0) { > + dev_err(dev, "cannot register PWM: %d\n", ret); > + goto unregister_clk; > + } > + > + /* Enable PWM */ > + ret = pwm_sifive_enable(chip, true); > + if (ret) > + dev_warn(dev, "cannot Enable PWM: %d\n", ret); s/E/e/ > + > + if (!pwm_is_enabled(pwm->chip.pwms)) > + clk_disable(pwm->clk); You check only the first pwm here, while you must not disable the clock if any pwm is running, right? > + > + platform_set_drvdata(pdev, pwm); > + dev_dbg(dev, "SiFive PWM chip registered %d PWMs\n", chip->npwm); > + > + return 0; > + > +unregister_clk: > + clk_notifier_unregister(pwm->clk, &pwm->notifier); > +disable_clk: > + clk_disable_unprepare(pwm->clk); > + > + return ret; > +} > + > +static int pwm_sifive_remove(struct platform_device *dev) > +{ > + struct pwm_sifive_ddata *pwm = platform_get_drvdata(dev); > + int ret; > + > + ret = pwmchip_remove(&pwm->chip); > + clk_notifier_unregister(pwm->clk, &pwm->notifier); > + if (!pwm_is_enabled(pwm->chip.pwms)) > + clk_disable(pwm->clk); I think this must be: if (any pwm is enabled) clk_disable(pwm->clk); > + clk_unprepare(pwm->clk); > + return ret; > +} Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | http://www.pengutronix.de/ |
