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// 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");
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