diff options
Diffstat (limited to 'drivers/pwm/pwm-apple.c')
| -rw-r--r-- | drivers/pwm/pwm-apple.c | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-apple.c b/drivers/pwm/pwm-apple.c new file mode 100644 index 0000000000..8e7d67fb5f --- /dev/null +++ b/drivers/pwm/pwm-apple.c @@ -0,0 +1,160 @@ +// SPDX-License-Identifier: GPL-2.0 OR MIT +/* + * Driver for the Apple SoC PWM controller + * + * Copyright The Asahi Linux Contributors + * + * Limitations: + * - The writes to cycle registers are shadowed until a write to + * the control register. + * - If both OFF_CYCLES and ON_CYCLES are set to 0, the output + * is a constant off signal. + * - When APPLE_PWM_CTRL is set to 0, the output is constant low + */ + +#include <linux/mod_devicetable.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/pwm.h> +#include <linux/io.h> +#include <linux/clk.h> +#include <linux/math64.h> + +#define APPLE_PWM_CTRL 0x00 +#define APPLE_PWM_ON_CYCLES 0x1c +#define APPLE_PWM_OFF_CYCLES 0x18 + +#define APPLE_PWM_CTRL_ENABLE BIT(0) +#define APPLE_PWM_CTRL_MODE BIT(2) +#define APPLE_PWM_CTRL_UPDATE BIT(5) +#define APPLE_PWM_CTRL_TRIGGER BIT(9) +#define APPLE_PWM_CTRL_INVERT BIT(10) +#define APPLE_PWM_CTRL_OUTPUT_ENABLE BIT(14) + +struct apple_pwm { + struct pwm_chip chip; + void __iomem *base; + u64 clkrate; +}; + +static inline struct apple_pwm *to_apple_pwm(struct pwm_chip *chip) +{ + return container_of(chip, struct apple_pwm, chip); +} + +static int apple_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) +{ + struct apple_pwm *fpwm; + + if (state->polarity == PWM_POLARITY_INVERSED) + return -EINVAL; + + fpwm = to_apple_pwm(chip); + if (state->enabled) { + u64 on_cycles, off_cycles; + + on_cycles = mul_u64_u64_div_u64(fpwm->clkrate, + state->duty_cycle, NSEC_PER_SEC); + if (on_cycles > 0xFFFFFFFF) + on_cycles = 0xFFFFFFFF; + + off_cycles = mul_u64_u64_div_u64(fpwm->clkrate, + state->period, NSEC_PER_SEC) - on_cycles; + if (off_cycles > 0xFFFFFFFF) + off_cycles = 0xFFFFFFFF; + + writel(on_cycles, fpwm->base + APPLE_PWM_ON_CYCLES); + writel(off_cycles, fpwm->base + APPLE_PWM_OFF_CYCLES); + writel(APPLE_PWM_CTRL_ENABLE | APPLE_PWM_CTRL_OUTPUT_ENABLE | APPLE_PWM_CTRL_UPDATE, + fpwm->base + APPLE_PWM_CTRL); + } else { + writel(0, fpwm->base + APPLE_PWM_CTRL); + } + return 0; +} + +static int apple_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, + struct pwm_state *state) +{ + struct apple_pwm *fpwm; + u32 on_cycles, off_cycles, ctrl; + + fpwm = to_apple_pwm(chip); + + ctrl = readl(fpwm->base + APPLE_PWM_CTRL); + on_cycles = readl(fpwm->base + APPLE_PWM_ON_CYCLES); + off_cycles = readl(fpwm->base + APPLE_PWM_OFF_CYCLES); + + state->enabled = (ctrl & APPLE_PWM_CTRL_ENABLE) && (ctrl & APPLE_PWM_CTRL_OUTPUT_ENABLE); + state->polarity = PWM_POLARITY_NORMAL; + // on_cycles + off_cycles is 33 bits, NSEC_PER_SEC is 30, there is no overflow + state->duty_cycle = DIV64_U64_ROUND_UP((u64)on_cycles * NSEC_PER_SEC, fpwm->clkrate); + state->period = DIV64_U64_ROUND_UP(((u64)off_cycles + (u64)on_cycles) * + NSEC_PER_SEC, fpwm->clkrate); + + return 0; +} + +static const struct pwm_ops apple_pwm_ops = { + .apply = apple_pwm_apply, + .get_state = apple_pwm_get_state, + .owner = THIS_MODULE, +}; + +static int apple_pwm_probe(struct platform_device *pdev) +{ + struct apple_pwm *fpwm; + struct clk *clk; + int ret; + + fpwm = devm_kzalloc(&pdev->dev, sizeof(*fpwm), GFP_KERNEL); + if (!fpwm) + return -ENOMEM; + + fpwm->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(fpwm->base)) + return PTR_ERR(fpwm->base); + + clk = devm_clk_get_enabled(&pdev->dev, NULL); + if (IS_ERR(clk)) + return dev_err_probe(&pdev->dev, PTR_ERR(clk), "unable to get the clock"); + + /* + * Uses the 24MHz system clock on all existing devices, can only + * happen if the device tree is broken + * + * This check is done to prevent an overflow in .apply + */ + fpwm->clkrate = clk_get_rate(clk); + if (fpwm->clkrate > NSEC_PER_SEC) + return dev_err_probe(&pdev->dev, -EINVAL, "pwm clock out of range"); + + fpwm->chip.dev = &pdev->dev; + fpwm->chip.npwm = 1; + fpwm->chip.ops = &apple_pwm_ops; + + ret = devm_pwmchip_add(&pdev->dev, &fpwm->chip); + if (ret < 0) + return dev_err_probe(&pdev->dev, ret, "unable to add pwm chip"); + + return 0; +} + +static const struct of_device_id apple_pwm_of_match[] = { + { .compatible = "apple,s5l-fpwm" }, + {} +}; +MODULE_DEVICE_TABLE(of, apple_pwm_of_match); + +static struct platform_driver apple_pwm_driver = { + .probe = apple_pwm_probe, + .driver = { + .name = "apple-pwm", + .of_match_table = apple_pwm_of_match, + }, +}; +module_platform_driver(apple_pwm_driver); + +MODULE_DESCRIPTION("Apple SoC PWM driver"); +MODULE_LICENSE("Dual MIT/GPL"); |