Hello, On Thu, Jul 21, 2022 at 06:21:09PM +0100, Conor Dooley wrote: > From: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> > > Add a driver that supports the Microchip FPGA "soft" PWM IP core. > > Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> > --- > drivers/pwm/Kconfig | 10 + > drivers/pwm/Makefile | 1 + > drivers/pwm/pwm-microchip-core.c | 371 +++++++++++++++++++++++++++++++ > 3 files changed, 382 insertions(+) > create mode 100644 drivers/pwm/pwm-microchip-core.c > > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig > index 904de8d61828..007ea5750e73 100644 > --- a/drivers/pwm/Kconfig > +++ b/drivers/pwm/Kconfig > @@ -383,6 +383,16 @@ config PWM_MEDIATEK > To compile this driver as a module, choose M here: the module > will be called pwm-mediatek. > > +config PWM_MICROCHIP_CORE > + tristate "Microchip corePWM PWM support" > + depends on SOC_MICROCHIP_POLARFIRE || COMPILE_TEST > + depends on HAS_IOMEM && OF > + help > + PWM driver for Microchip FPGA soft IP core. > + > + To compile this driver as a module, choose M here: the module > + will be called pwm-microchip-core. > + > config PWM_MXS > tristate "Freescale MXS PWM support" > depends on ARCH_MXS || COMPILE_TEST > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile > index 5c08bdb817b4..43feb7cfc66a 100644 > --- a/drivers/pwm/Makefile > +++ b/drivers/pwm/Makefile > @@ -33,6 +33,7 @@ obj-$(CONFIG_PWM_LPSS_PCI) += pwm-lpss-pci.o > obj-$(CONFIG_PWM_LPSS_PLATFORM) += pwm-lpss-platform.o > obj-$(CONFIG_PWM_MESON) += pwm-meson.o > obj-$(CONFIG_PWM_MEDIATEK) += pwm-mediatek.o > +obj-$(CONFIG_PWM_MICROCHIP_CORE) += pwm-microchip-core.o > obj-$(CONFIG_PWM_MTK_DISP) += pwm-mtk-disp.o > obj-$(CONFIG_PWM_MXS) += pwm-mxs.o > obj-$(CONFIG_PWM_NTXEC) += pwm-ntxec.o > diff --git a/drivers/pwm/pwm-microchip-core.c b/drivers/pwm/pwm-microchip-core.c > new file mode 100644 > index 000000000000..2d12248f86b8 > --- /dev/null > +++ b/drivers/pwm/pwm-microchip-core.c > @@ -0,0 +1,371 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * corePWM driver for Microchip "soft" FPGA IP cores. > + * > + * Copyright (c) 2021-2022 Microchip Corporation. All rights reserved. > + * Author: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> > + * Documentation: > + * https://www.microsemi.com/document-portal/doc_download/1245275-corepwm-hb > + * > + * Limitations: > + * - If the IP block is configured without "shadow registers", all register > + * writes will take effect immediately, causing glitches on the output. > + * If shadow registers *are* enabled, a write to the "SYNC_UPDATE" register > + * notifies the core that it needs to update the registers defining the > + * waveform from the contents of the "shadow registers". > + * - The IP block has no concept of a duty cycle, only rising/falling edges of > + * the waveform. Unfortunately, if the rising & falling edges registers have > + * the same value written to them the IP block will do whichever of a rising > + * or a falling edge is possible. I.E. a 50% waveform at twice the requested > + * period. Therefore to get a 0% waveform, the output is set the max high/low > + * time depending on polarity. > + * - The PWM period is set for the whole IP block not per channel. The driver > + * will only change the period if no other PWM output is enabled. > + */ > + > +#include <linux/clk.h> > +#include <linux/delay.h> > +#include <linux/err.h> > +#include <linux/io.h> > +#include <linux/math.h> > +#include <linux/module.h> > +#include <linux/mutex.h> > +#include <linux/of_device.h> > +#include <linux/platform_device.h> > +#include <linux/pwm.h> > + > +#define PREG_TO_VAL(PREG) ((PREG) + 1) > + > +#define MCHPCOREPWM_PRESCALE_MAX 0x100 > +#define MCHPCOREPWM_PERIOD_STEPS_MAX 0xff > +#define MCHPCOREPWM_PERIOD_MAX 0xff00 > + > +#define MCHPCOREPWM_PRESCALE 0x00 > +#define MCHPCOREPWM_PERIOD 0x04 > +#define MCHPCOREPWM_EN(i) (0x08 + 0x04 * (i)) /* 0x08, 0x0c */ > +#define MCHPCOREPWM_POSEDGE(i) (0x10 + 0x08 * (i)) /* 0x10, 0x18, ..., 0x88 */ > +#define MCHPCOREPWM_NEGEDGE(i) (0x14 + 0x08 * (i)) /* 0x14, 0x1c, ..., 0x8c */ > +#define MCHPCOREPWM_SYNC_UPD 0xe4 > + > +struct mchp_core_pwm_chip { > + struct pwm_chip chip; > + struct clk *clk; > + struct mutex lock; /* protect the shared period */ > + void __iomem *base; > + u32 sync_update_mask; > + u16 channel_enabled; > +}; > + > +static inline struct mchp_core_pwm_chip *to_mchp_core_pwm(struct pwm_chip *chip) > +{ > + return container_of(chip, struct mchp_core_pwm_chip, chip); > +} > + > +static void mchp_core_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm, > + bool enable, u64 period) > +{ > + struct mchp_core_pwm_chip *mchp_core_pwm = to_mchp_core_pwm(chip); > + u8 channel_enable, reg_offset, shift; > + > + /* > + * There are two adjacent 8 bit control regs, the lower reg controls > + * 0-7 and the upper reg 8-15. Check if the pwm is in the upper reg > + * and if so, offset by the bus width. > + */ > + reg_offset = MCHPCOREPWM_EN(pwm->hwpwm >> 3); > + shift = pwm->hwpwm & 7; > + > + channel_enable = readb_relaxed(mchp_core_pwm->base + reg_offset); > + channel_enable &= ~(1 << shift); > + channel_enable |= (enable << shift); > + > + writel_relaxed(channel_enable, mchp_core_pwm->base + reg_offset); > + mchp_core_pwm->channel_enabled &= ~BIT(pwm->hwpwm); > + mchp_core_pwm->channel_enabled |= enable << pwm->hwpwm; > + > + /* > + * Notify the block to update the waveform from the shadow registers. > + * The updated values will not appear on the bus until they have been > + * applied to the waveform at the beginning of the next period. We must > + * write these registers and wait for them to be applied before calling > + * enable(). What does "calling enable()" mean? There is no such function or callback with that name?! > + */ > + if (mchp_core_pwm->sync_update_mask & (1 << pwm->hwpwm)) { > + writel_relaxed(1U, mchp_core_pwm->base + MCHPCOREPWM_SYNC_UPD); > + usleep_range(period, period * 2); So if period = 5000 *ns* you sleep between 5000 and 10000 *us* here? > + } > +} > + > +static u64 mchp_core_pwm_calc_duty(struct pwm_chip *chip, struct pwm_device *pwm, > + const struct pwm_state *state, u8 prescale, u8 period_steps) > +{ > + struct mchp_core_pwm_chip *mchp_core_pwm = to_mchp_core_pwm(chip); > + u64 duty_steps, period, tmp; > + u16 prescale_val = PREG_TO_VAL(prescale); > + u8 period_steps_val = PREG_TO_VAL(period_steps); Can it happen that period_steps is 0xff? Then period_steps_val ends up being 0. > + > + period = period_steps_val * prescale_val * NSEC_PER_SEC; > + period = DIV64_U64_ROUND_UP(period, clk_get_rate(mchp_core_pwm->clk)); The value you are calculating for period isn't used?! > + > + /* > + * Calculate the duty cycle in multiples of the prescaled period: > + * duty_steps = duty_in_ns / step_in_ns > + * step_in_ns = (prescale * NSEC_PER_SEC) / clk_rate > + * The code below is rearranged slightly to only divide once. > + */ > + duty_steps = state->duty_cycle * clk_get_rate(mchp_core_pwm->clk); > + tmp = prescale_val * NSEC_PER_SEC; > + return div64_u64(duty_steps, tmp); > +} > + > +static void mchp_core_pwm_apply_duty(struct pwm_chip *chip, struct pwm_device *pwm, > + const struct pwm_state *state, u64 duty_steps, u8 period_steps) > +{ > + struct mchp_core_pwm_chip *mchp_core_pwm = to_mchp_core_pwm(chip); > + u8 posedge, negedge; > + u8 period_steps_val = PREG_TO_VAL(period_steps); > + > + /* > + * Turn the output on unless posedge == negedge, in which case the > + * duty is intended to be 0, but limitations of the IP block don't > + * allow a zero length duty cycle - so just set the max high/low time > + * respectively. > + */ I don't understand that comment. Maybe you mean?: /* * Setting posedge == negedge doesn't yield a constant output, * so that's an unsuitable setting to model duty_steps = 0. * In that case set the unwanted edge to a value that never * triggers. */ > + if (state->polarity == PWM_POLARITY_INVERSED) { > + negedge = !duty_steps ? period_steps_val : 0u; > + posedge = duty_steps; > + } else { > + posedge = !duty_steps ? period_steps_val : 0u; > + negedge = duty_steps; > + } > + > + writel_relaxed(posedge, mchp_core_pwm->base + MCHPCOREPWM_POSEDGE(pwm->hwpwm)); > + writel_relaxed(negedge, mchp_core_pwm->base + MCHPCOREPWM_NEGEDGE(pwm->hwpwm)); > +} > + > +static int mchp_core_pwm_calc_period(struct pwm_chip *chip, const struct pwm_state *state, > + u8 *prescale, u8 *period_steps) > +{ > + struct mchp_core_pwm_chip *mchp_core_pwm = to_mchp_core_pwm(chip); > + u64 tmp, clk_rate; > + > + /* > + * Calculate the period cycles and prescale values. > + * The registers are each 8 bits wide & multiplied to compute the period > + * using the formula: > + * (clock_period) * (prescale + 1) * (period_steps + 1) > + * so the maximum period that can be generated is 0x10000 times the > + * period of the input clock. > + * However, due to the design of the "hardware", it is not possible to > + * attain a 100% duty cycle if the full range of period_steps is used. > + * Therefore period_steps is restricted to 0xFE and the maximum multiple > + * of the clock period attainable is 0xFF00. > + */ > + clk_rate = clk_get_rate(mchp_core_pwm->clk); > + > + /* > + * If clk_rate is too big, the following multiplication might overflow. > + * However this is implausible, as the fabric of current FPGAs cannot > + * provide clocks at a rate high enough. > + */ > + if (clk_rate >= NSEC_PER_SEC) > + return -EINVAL; > + > + tmp = mul_u64_u64_div_u64(state->period, clk_rate, NSEC_PER_SEC); > + > + if (tmp >= MCHPCOREPWM_PERIOD_MAX) { > + *prescale = MCHPCOREPWM_PRESCALE_MAX - 1; why -1 here? > + *period_steps = MCHPCOREPWM_PERIOD_STEPS_MAX - 1; > + return 0; > + } > + > + *prescale = div_u64(tmp, MCHPCOREPWM_PERIOD_STEPS_MAX); > + /* PREG_TO_VAL() can produce a value larger than UINT8_MAX */ That should explain the cast to u32? If this were really necessary (hint: it isn't) it would IMHO be better to hide that cast in the macro. > + *period_steps = div_u64(tmp, PREG_TO_VAL((u32)*prescale)) - 1; > + > + return 0; > +} > + > +static inline void mchp_core_pwm_apply_period(struct mchp_core_pwm_chip *mchp_core_pwm, > + u8 prescale, u8 period_steps) > +{ > + writel_relaxed(prescale, mchp_core_pwm->base + MCHPCOREPWM_PRESCALE); > + writel_relaxed(period_steps, mchp_core_pwm->base + MCHPCOREPWM_PERIOD); > +} > + > +static int mchp_core_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, > + const struct pwm_state *state) > +{ > + struct mchp_core_pwm_chip *mchp_core_pwm = to_mchp_core_pwm(chip); > + struct pwm_state current_state = pwm->state; > + bool period_locked; > + u64 duty_steps; > + u8 prescale, period_steps, hw_prescale, hw_period_steps; > + int ret; > + > + ret = mutex_lock_interruptible(&mchp_core_pwm->lock); > + if (ret) > + return ret; I would have used mutex_lock() here. Why should a signal prevent reconfiguration of the PWM? > + > + if (!state->enabled) { > + mchp_core_pwm_enable(chip, pwm, false, current_state.period); > + mutex_unlock(&mchp_core_pwm->lock); > + return 0; > + } > + > + /* > + * If the only thing that has changed is the duty cycle or the polarity, > + * we can shortcut the calculations and just compute/apply the new duty > + * cycle pos & neg edges > + * As all the channels share the same period, do not allow it to be > + * changed if any other channels are enabled. > + * If the period is locked, it may not be possible to use a period > + * less than that requested. In that case, we just abort. > + */ > + period_locked = mchp_core_pwm->channel_enabled & ~(1 << pwm->hwpwm); > + > + if (period_locked) { > + mchp_core_pwm_calc_period(chip, state, &prescale, &period_steps); > + hw_prescale = readb_relaxed(mchp_core_pwm->base + MCHPCOREPWM_PRESCALE); > + hw_period_steps = readb_relaxed(mchp_core_pwm->base + MCHPCOREPWM_PERIOD); > + > + if ((period_steps * prescale) < (hw_period_steps * hw_prescale)) { You need if ((period_steps + 1) * (prescale + 1) < (hw_period_steps + 1) * (hw_prescale + 1)) here, don't you? > + mutex_unlock(&mchp_core_pwm->lock); > + return -EINVAL; > + } > + > + prescale = hw_prescale; > + period_steps = hw_period_steps; The two hw_* variables are only used in this branch. So their declaration can move into here. > + } else if (!current_state.enabled || current_state.period != state->period) { > + ret = mchp_core_pwm_calc_period(chip, state, &prescale, &period_steps); > + if (ret) { > + mutex_unlock(&mchp_core_pwm->lock); > + return ret; > + } > + mchp_core_pwm_apply_period(mchp_core_pwm, prescale, period_steps); > + } else { > + prescale = readb_relaxed(mchp_core_pwm->base + MCHPCOREPWM_PRESCALE); > + period_steps = readb_relaxed(mchp_core_pwm->base + MCHPCOREPWM_PERIOD); > + } > + > + duty_steps = mchp_core_pwm_calc_duty(chip, pwm, state, prescale, period_steps); > + > + /* > + * Because the period is per channel, it is possible that the requested > + * duty cycle is longer than the period, in which case cap it to the > + * period, IOW a 100% duty cycle. > + */ > + if (duty_steps > period_steps) > + duty_steps = period_steps + 1; > + > + mchp_core_pwm_apply_duty(chip, pwm, state, duty_steps, period_steps); > + > + mchp_core_pwm_enable(chip, pwm, true, state->period); > + > + mutex_unlock(&mchp_core_pwm->lock); > + > + return 0; > +} > + > +static void mchp_core_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, > + struct pwm_state *state) > +{ > + struct mchp_core_pwm_chip *mchp_core_pwm = to_mchp_core_pwm(chip); > + u16 prescale; > + u8 period_steps, duty_steps, posedge, negedge; > + int ret; > + > + ret = mutex_lock_interruptible(&mchp_core_pwm->lock); > + if (ret) > + return; > + > + if (mchp_core_pwm->channel_enabled & (1 << pwm->hwpwm)) channel_enabled is initialized to 0 in .probe(), so a PWM is never diagnosed to be running when the core initially wants to determine the current state. > + state->enabled = true; > + else > + state->enabled = false; > + > + prescale = PREG_TO_VAL(readb_relaxed(mchp_core_pwm->base + MCHPCOREPWM_PRESCALE)); > + > + period_steps = PREG_TO_VAL(readb_relaxed(mchp_core_pwm->base + MCHPCOREPWM_PERIOD)); > + state->period = period_steps * prescale * NSEC_PER_SEC; > + state->period = DIV64_U64_ROUND_UP(state->period, clk_get_rate(mchp_core_pwm->clk)); > + > + posedge = readb_relaxed(mchp_core_pwm->base + MCHPCOREPWM_POSEDGE(pwm->hwpwm)); > + negedge = readb_relaxed(mchp_core_pwm->base + MCHPCOREPWM_NEGEDGE(pwm->hwpwm)); > + > + if (negedge == posedge) { > + state->duty_cycle = state->period / 2; I thought that's: state->duty_cycle = state->period; state->period *= 2; ? > + } else { > + duty_steps = abs((s16)posedge - (s16)negedge); > + state->duty_cycle = duty_steps * prescale * NSEC_PER_SEC; > + state->duty_cycle = DIV64_U64_ROUND_UP(state->duty_cycle, > + clk_get_rate(mchp_core_pwm->clk)); > + } > + > + state->polarity = negedge < posedge ? PWM_POLARITY_INVERSED : PWM_POLARITY_NORMAL; > + > + mutex_unlock(&mchp_core_pwm->lock); > +} > + > +static const struct pwm_ops mchp_core_pwm_ops = { > + .apply = mchp_core_pwm_apply, > + .get_state = mchp_core_pwm_get_state, > + .owner = THIS_MODULE, > +}; > + > +static const struct of_device_id mchp_core_of_match[] = { > + { > + .compatible = "microchip,corepwm-rtl-v4", > + }, > + { /* sentinel */ } > +}; > +MODULE_DEVICE_TABLE(of, mchp_core_of_match); > + > +static int mchp_core_pwm_probe(struct platform_device *pdev) > +{ > + struct mchp_core_pwm_chip *mchp_pwm; > + struct resource *regs; > + int ret; > + > + mchp_pwm = devm_kzalloc(&pdev->dev, sizeof(*mchp_pwm), GFP_KERNEL); > + if (!mchp_pwm) > + return -ENOMEM; > + > + mchp_pwm->base = devm_platform_get_and_ioremap_resource(pdev, 0, ®s); > + if (IS_ERR(mchp_pwm->base)) > + return PTR_ERR(mchp_pwm->base); > + > + mchp_pwm->clk = devm_clk_get_enabled(&pdev->dev, NULL); > + if (IS_ERR(mchp_pwm->clk)) > + return dev_err_probe(&pdev->dev, PTR_ERR(mchp_pwm->clk), > + "failed to get PWM clock\n"); > + > + if (of_property_read_u32(pdev->dev.of_node, "microchip,sync-update-mask", > + &mchp_pwm->sync_update_mask)) > + mchp_pwm->sync_update_mask = 0u; > + > + mutex_init(&mchp_pwm->lock); > + > + mchp_pwm->chip.dev = &pdev->dev; > + mchp_pwm->chip.ops = &mchp_core_pwm_ops; > + mchp_pwm->chip.npwm = 16; > + > + ret = devm_pwmchip_add(&pdev->dev, &mchp_pwm->chip); > + if (ret < 0) > + return dev_err_probe(&pdev->dev, ret, "failed to add PWM chip\n"); > + > + return 0; > +} > + > +static struct platform_driver mchp_core_pwm_driver = { > + .driver = { > + .name = "mchp-core-pwm", > + .of_match_table = mchp_core_of_match, > + }, > + .probe = mchp_core_pwm_probe, > +}; > +module_platform_driver(mchp_core_pwm_driver); > + > +MODULE_LICENSE("GPL"); > +MODULE_AUTHOR("Conor Dooley <conor.dooley@xxxxxxxxxxxxx>"); > +MODULE_DESCRIPTION("corePWM driver for Microchip FPGAs"); Best regards Uwe -- Pengutronix e.K. | Uwe Kleine-König | Industrial Linux Solutions | https://www.pengutronix.de/ |
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