| // SPDX-License-Identifier: GPL-2.0-only |
| // Copyright (C) 2014 Broadcom Corporation |
| |
| #include <linux/clk.h> |
| #include <linux/delay.h> |
| #include <linux/err.h> |
| #include <linux/io.h> |
| #include <linux/ioport.h> |
| #include <linux/math64.h> |
| #include <linux/module.h> |
| #include <linux/of.h> |
| #include <linux/platform_device.h> |
| #include <linux/pwm.h> |
| #include <linux/slab.h> |
| #include <linux/types.h> |
| |
| /* |
| * The Kona PWM has some unusual characteristics. Here are the main points. |
| * |
| * 1) There is no disable bit and the hardware docs advise programming a zero |
| * duty to achieve output equivalent to that of a normal disable operation. |
| * |
| * 2) Changes to prescale, duty, period, and polarity do not take effect until |
| * a subsequent rising edge of the trigger bit. |
| * |
| * 3) If the smooth bit and trigger bit are both low, the output is a constant |
| * high signal. Otherwise, the earlier waveform continues to be output. |
| * |
| * 4) If the smooth bit is set on the rising edge of the trigger bit, output |
| * will transition to the new settings on a period boundary (which could be |
| * seconds away). If the smooth bit is clear, new settings will be applied |
| * as soon as possible (the hardware always has a 400ns delay). |
| * |
| * 5) When the external clock that feeds the PWM is disabled, output is pegged |
| * high or low depending on its state at that exact instant. |
| */ |
| |
| #define PWM_CONTROL_OFFSET 0x00000000 |
| #define PWM_CONTROL_SMOOTH_SHIFT(chan) (24 + (chan)) |
| #define PWM_CONTROL_TYPE_SHIFT(chan) (16 + (chan)) |
| #define PWM_CONTROL_POLARITY_SHIFT(chan) (8 + (chan)) |
| #define PWM_CONTROL_TRIGGER_SHIFT(chan) (chan) |
| |
| #define PRESCALE_OFFSET 0x00000004 |
| #define PRESCALE_SHIFT(chan) ((chan) << 2) |
| #define PRESCALE_MASK(chan) (0x7 << PRESCALE_SHIFT(chan)) |
| #define PRESCALE_MIN 0x00000000 |
| #define PRESCALE_MAX 0x00000007 |
| |
| #define PERIOD_COUNT_OFFSET(chan) (0x00000008 + ((chan) << 3)) |
| #define PERIOD_COUNT_MIN 0x00000002 |
| #define PERIOD_COUNT_MAX 0x00ffffff |
| |
| #define DUTY_CYCLE_HIGH_OFFSET(chan) (0x0000000c + ((chan) << 3)) |
| #define DUTY_CYCLE_HIGH_MIN 0x00000000 |
| #define DUTY_CYCLE_HIGH_MAX 0x00ffffff |
| |
| struct kona_pwmc { |
| struct pwm_chip chip; |
| void __iomem *base; |
| struct clk *clk; |
| }; |
| |
| static inline struct kona_pwmc *to_kona_pwmc(struct pwm_chip *chip) |
| { |
| return container_of(chip, struct kona_pwmc, chip); |
| } |
| |
| /* |
| * Clear trigger bit but set smooth bit to maintain old output. |
| */ |
| static void kona_pwmc_prepare_for_settings(struct kona_pwmc *kp, |
| unsigned int chan) |
| { |
| unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET); |
| |
| value |= 1 << PWM_CONTROL_SMOOTH_SHIFT(chan); |
| value &= ~(1 << PWM_CONTROL_TRIGGER_SHIFT(chan)); |
| writel(value, kp->base + PWM_CONTROL_OFFSET); |
| |
| /* |
| * There must be a min 400ns delay between clearing trigger and setting |
| * it. Failing to do this may result in no PWM signal. |
| */ |
| ndelay(400); |
| } |
| |
| static void kona_pwmc_apply_settings(struct kona_pwmc *kp, unsigned int chan) |
| { |
| unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET); |
| |
| /* Set trigger bit and clear smooth bit to apply new settings */ |
| value &= ~(1 << PWM_CONTROL_SMOOTH_SHIFT(chan)); |
| value |= 1 << PWM_CONTROL_TRIGGER_SHIFT(chan); |
| writel(value, kp->base + PWM_CONTROL_OFFSET); |
| |
| /* Trigger bit must be held high for at least 400 ns. */ |
| ndelay(400); |
| } |
| |
| static int kona_pwmc_config(struct pwm_chip *chip, struct pwm_device *pwm, |
| u64 duty_ns, u64 period_ns) |
| { |
| struct kona_pwmc *kp = to_kona_pwmc(chip); |
| u64 div, rate; |
| unsigned long prescale = PRESCALE_MIN, pc, dc; |
| unsigned int value, chan = pwm->hwpwm; |
| |
| /* |
| * Find period count, duty count and prescale to suit duty_ns and |
| * period_ns. This is done according to formulas described below: |
| * |
| * period_ns = 10^9 * (PRESCALE + 1) * PC / PWM_CLK_RATE |
| * duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE |
| * |
| * PC = (PWM_CLK_RATE * period_ns) / (10^9 * (PRESCALE + 1)) |
| * DC = (PWM_CLK_RATE * duty_ns) / (10^9 * (PRESCALE + 1)) |
| */ |
| |
| rate = clk_get_rate(kp->clk); |
| |
| while (1) { |
| div = 1000000000; |
| div *= 1 + prescale; |
| pc = mul_u64_u64_div_u64(rate, period_ns, div); |
| dc = mul_u64_u64_div_u64(rate, duty_ns, div); |
| |
| /* If duty_ns or period_ns are not achievable then return */ |
| if (pc < PERIOD_COUNT_MIN) |
| return -EINVAL; |
| |
| /* If pc and dc are in bounds, the calculation is done */ |
| if (pc <= PERIOD_COUNT_MAX && dc <= DUTY_CYCLE_HIGH_MAX) |
| break; |
| |
| /* Otherwise, increase prescale and recalculate pc and dc */ |
| if (++prescale > PRESCALE_MAX) |
| return -EINVAL; |
| } |
| |
| kona_pwmc_prepare_for_settings(kp, chan); |
| |
| value = readl(kp->base + PRESCALE_OFFSET); |
| value &= ~PRESCALE_MASK(chan); |
| value |= prescale << PRESCALE_SHIFT(chan); |
| writel(value, kp->base + PRESCALE_OFFSET); |
| |
| writel(pc, kp->base + PERIOD_COUNT_OFFSET(chan)); |
| |
| writel(dc, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan)); |
| |
| kona_pwmc_apply_settings(kp, chan); |
| |
| return 0; |
| } |
| |
| static int kona_pwmc_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm, |
| enum pwm_polarity polarity) |
| { |
| struct kona_pwmc *kp = to_kona_pwmc(chip); |
| unsigned int chan = pwm->hwpwm; |
| unsigned int value; |
| int ret; |
| |
| ret = clk_prepare_enable(kp->clk); |
| if (ret < 0) { |
| dev_err(chip->dev, "failed to enable clock: %d\n", ret); |
| return ret; |
| } |
| |
| kona_pwmc_prepare_for_settings(kp, chan); |
| |
| value = readl(kp->base + PWM_CONTROL_OFFSET); |
| |
| if (polarity == PWM_POLARITY_NORMAL) |
| value |= 1 << PWM_CONTROL_POLARITY_SHIFT(chan); |
| else |
| value &= ~(1 << PWM_CONTROL_POLARITY_SHIFT(chan)); |
| |
| writel(value, kp->base + PWM_CONTROL_OFFSET); |
| |
| kona_pwmc_apply_settings(kp, chan); |
| |
| clk_disable_unprepare(kp->clk); |
| |
| return 0; |
| } |
| |
| static int kona_pwmc_enable(struct pwm_chip *chip, struct pwm_device *pwm) |
| { |
| struct kona_pwmc *kp = to_kona_pwmc(chip); |
| int ret; |
| |
| ret = clk_prepare_enable(kp->clk); |
| if (ret < 0) { |
| dev_err(chip->dev, "failed to enable clock: %d\n", ret); |
| return ret; |
| } |
| |
| return 0; |
| } |
| |
| static void kona_pwmc_disable(struct pwm_chip *chip, struct pwm_device *pwm) |
| { |
| struct kona_pwmc *kp = to_kona_pwmc(chip); |
| unsigned int chan = pwm->hwpwm; |
| unsigned int value; |
| |
| kona_pwmc_prepare_for_settings(kp, chan); |
| |
| /* Simulate a disable by configuring for zero duty */ |
| writel(0, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan)); |
| writel(0, kp->base + PERIOD_COUNT_OFFSET(chan)); |
| |
| /* Set prescale to 0 for this channel */ |
| value = readl(kp->base + PRESCALE_OFFSET); |
| value &= ~PRESCALE_MASK(chan); |
| writel(value, kp->base + PRESCALE_OFFSET); |
| |
| kona_pwmc_apply_settings(kp, chan); |
| |
| clk_disable_unprepare(kp->clk); |
| } |
| |
| static int kona_pwmc_apply(struct pwm_chip *chip, struct pwm_device *pwm, |
| const struct pwm_state *state) |
| { |
| int err; |
| struct kona_pwmc *kp = to_kona_pwmc(chip); |
| bool enabled = pwm->state.enabled; |
| |
| if (state->polarity != pwm->state.polarity) { |
| if (enabled) { |
| kona_pwmc_disable(chip, pwm); |
| enabled = false; |
| } |
| |
| err = kona_pwmc_set_polarity(chip, pwm, state->polarity); |
| if (err) |
| return err; |
| |
| pwm->state.polarity = state->polarity; |
| } |
| |
| if (!state->enabled) { |
| if (enabled) |
| kona_pwmc_disable(chip, pwm); |
| return 0; |
| } else if (!enabled) { |
| /* |
| * This is a bit special here, usually the PWM should only be |
| * enabled when duty and period are setup. But before this |
| * driver was converted to .apply it was done the other way |
| * around and so this behaviour was kept even though this might |
| * result in a glitch. This might be improvable by someone with |
| * hardware and/or documentation. |
| */ |
| err = kona_pwmc_enable(chip, pwm); |
| if (err) |
| return err; |
| } |
| |
| err = kona_pwmc_config(pwm->chip, pwm, state->duty_cycle, state->period); |
| if (err && !pwm->state.enabled) |
| clk_disable_unprepare(kp->clk); |
| |
| return err; |
| } |
| |
| static const struct pwm_ops kona_pwm_ops = { |
| .apply = kona_pwmc_apply, |
| .owner = THIS_MODULE, |
| }; |
| |
| static int kona_pwmc_probe(struct platform_device *pdev) |
| { |
| struct kona_pwmc *kp; |
| unsigned int chan; |
| unsigned int value = 0; |
| int ret = 0; |
| |
| kp = devm_kzalloc(&pdev->dev, sizeof(*kp), GFP_KERNEL); |
| if (kp == NULL) |
| return -ENOMEM; |
| |
| kp->chip.dev = &pdev->dev; |
| kp->chip.ops = &kona_pwm_ops; |
| kp->chip.npwm = 6; |
| |
| kp->base = devm_platform_ioremap_resource(pdev, 0); |
| if (IS_ERR(kp->base)) |
| return PTR_ERR(kp->base); |
| |
| kp->clk = devm_clk_get(&pdev->dev, NULL); |
| if (IS_ERR(kp->clk)) { |
| dev_err(&pdev->dev, "failed to get clock: %ld\n", |
| PTR_ERR(kp->clk)); |
| return PTR_ERR(kp->clk); |
| } |
| |
| ret = clk_prepare_enable(kp->clk); |
| if (ret < 0) { |
| dev_err(&pdev->dev, "failed to enable clock: %d\n", ret); |
| return ret; |
| } |
| |
| /* Set push/pull for all channels */ |
| for (chan = 0; chan < kp->chip.npwm; chan++) |
| value |= (1 << PWM_CONTROL_TYPE_SHIFT(chan)); |
| |
| writel(value, kp->base + PWM_CONTROL_OFFSET); |
| |
| clk_disable_unprepare(kp->clk); |
| |
| ret = devm_pwmchip_add(&pdev->dev, &kp->chip); |
| if (ret < 0) |
| dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret); |
| |
| return ret; |
| } |
| |
| static const struct of_device_id bcm_kona_pwmc_dt[] = { |
| { .compatible = "brcm,kona-pwm" }, |
| { }, |
| }; |
| MODULE_DEVICE_TABLE(of, bcm_kona_pwmc_dt); |
| |
| static struct platform_driver kona_pwmc_driver = { |
| .driver = { |
| .name = "bcm-kona-pwm", |
| .of_match_table = bcm_kona_pwmc_dt, |
| }, |
| .probe = kona_pwmc_probe, |
| }; |
| module_platform_driver(kona_pwmc_driver); |
| |
| MODULE_AUTHOR("Broadcom Corporation <bcm-kernel-feedback-list@broadcom.com>"); |
| MODULE_AUTHOR("Tim Kryger <tkryger@broadcom.com>"); |
| MODULE_DESCRIPTION("Broadcom Kona PWM driver"); |
| MODULE_LICENSE("GPL v2"); |