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pipcetpipcet
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FPWM driver.
See AsahiLinux#5
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‎drivers/pwm/Kconfig‎

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@@ -51,6 +51,16 @@ config PWM_AB8500
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To compile this driver as a module, choose M here: the module
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will be called pwm-ab8500.
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config PWM_APPLE_M1
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tristate "Apple M1 FPWM support"
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depends on ARCH_APPLE
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help
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PWM driver for the Apple M1's FPWM (which controls the
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keyboard backlight in some MacBook Pros)
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To compile this driver as a module, choose M here; the module
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will be called pwm-apple-m1-fpwm.
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config PWM_ATMEL
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tristate "Atmel PWM support"
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depends on ARCH_AT91 || COMPILE_TEST

‎drivers/pwm/Makefile‎

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obj-$(CONFIG_PWM) += core.o
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obj-$(CONFIG_PWM_SYSFS) += sysfs.o
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obj-$(CONFIG_PWM_AB8500) += pwm-ab8500.o
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obj-$(CONFIG_PWM_APPLE_M1) += pwm-apple-m1.o
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obj-$(CONFIG_PWM_ATMEL) += pwm-atmel.o
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obj-$(CONFIG_PWM_ATMEL_HLCDC_PWM) += pwm-atmel-hlcdc.o
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obj-$(CONFIG_PWM_ATMEL_TCB) += pwm-atmel-tcb.o

‎drivers/pwm/pwm-apple-m1.c‎

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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Driver for Apple M1 FPWM. Used for the keyboard backlight on at
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* least some MacBook Pros.
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*
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* Copyright (C) 2021 Pip Cet <pipcet@gmail.com>
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*
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* Based on pwm-twl-led.c, which is:
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*
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* Copyright (C) 2012 Texas Instruments
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* Author: Peter Ujfalusi <peter.ujfalusi@ti.com>
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*/
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#include <linux/clk.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/io.h>
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#include <linux/platform_device.h>
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#include <linux/pwm.h>
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#include <linux/slab.h>
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#define FPWM_CONTROL 0x00
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#define FPWM_CONTROL_UPDATE 0x4239
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#define FPWM_CONTROL_DISABLE 0
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#define FPWM_STATUS 0x08
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#define FPWM_COUNT_OFF 0x18
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#define FPWM_COUNT_ON 0x1c
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#define FPWM_HZ (24 * 1000 * 1000)
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struct fpwm_chip {
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struct pwm_chip chip;
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void __iomem *regbase;
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struct clk *clk;
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struct mutex mutex; // XXX
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};
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static inline struct fpwm_chip *to_fpwm(struct pwm_chip *chip)
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{
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return container_of(chip, struct fpwm_chip, chip);
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}
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static int fpwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
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int duty_ns, int period_ns)
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{
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struct fpwm_chip *fpwm = to_fpwm(chip);
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long duty_ticks = duty_ns * 3L / (1000000000L * 3 / FPWM_HZ);
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long period_ticks = period_ns * 3L / (1000000000L * 3 / FPWM_HZ);
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long off_ticks = period_ticks - duty_ticks;
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writel(duty_ticks, fpwm->regbase + FPWM_COUNT_ON);
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writel(off_ticks, fpwm->regbase + FPWM_COUNT_OFF);
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writel(FPWM_CONTROL_UPDATE, fpwm->regbase + FPWM_CONTROL);
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return 0;
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}
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static int fpwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct fpwm_chip *fpwm = to_fpwm(chip);
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writel(FPWM_CONTROL_UPDATE, fpwm->regbase + FPWM_CONTROL);
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return 0;
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}
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static void fpwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
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{
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struct fpwm_chip *fpwm = to_fpwm(chip);
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writel(FPWM_CONTROL_DISABLE, fpwm->regbase + FPWM_CONTROL);
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}
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static const struct pwm_ops fpwm_ops = {
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.enable = fpwm_enable,
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.disable = fpwm_disable,
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.config = fpwm_config,
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.owner = THIS_MODULE,
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};
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static int fpwm_probe(struct platform_device *pdev)
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{
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struct fpwm_chip *fpwm;
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struct resource *rsrc;
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int ret;
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fpwm = devm_kzalloc(&pdev->dev, sizeof(*fpwm), GFP_KERNEL);
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if (!fpwm)
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return -ENOMEM;
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fpwm->chip.ops = &fpwm_ops;
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fpwm->chip.npwm = 1;
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fpwm->chip.dev = &pdev->dev;
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fpwm->chip.base = -1;
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mutex_init(&fpwm->mutex);
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ret = pwmchip_add(&fpwm->chip);
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if(ret < 0)
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return ret;
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platform_set_drvdata(pdev, fpwm);
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rsrc = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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fpwm->regbase = devm_ioremap_resource(&pdev->dev, rsrc);
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if(IS_ERR(fpwm->regbase))
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return PTR_ERR(fpwm->regbase);
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fpwm->clk = devm_clk_get(&pdev->dev, NULL);
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if(IS_ERR(fpwm->clk)) {
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dev_err(&pdev->dev, "unable to get clock: %ld\n",
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PTR_ERR(fpwm->clk));
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return PTR_ERR(fpwm->clk);
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}
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ret = clk_prepare_enable(fpwm->clk);
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if(ret)
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return ret;
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return 0;
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}
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static int fpwm_remove(struct platform_device *pdev)
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{
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struct fpwm_chip *fpwm = platform_get_drvdata(pdev);
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int ret = pwmchip_remove(&fpwm->chip);
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if (ret < 0)
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return ret;
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clk_disable_unprepare(fpwm->clk);
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return 0;
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}
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#ifdef CONFIG_OF
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static const struct of_device_id fpwm_of_match[] = {
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{ .compatible = "apple,fpwm-t8101" },
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{ .compatible = "apple,fpwm-s5l8920x" },
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{ },
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};
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MODULE_DEVICE_TABLE(of, fpwm_of_match);
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#endif
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static struct platform_driver fpwm_driver = {
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.driver = {
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.name = "apple-m1-fpwm",
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.of_match_table = of_match_ptr(fpwm_of_match),
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},
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.probe = fpwm_probe,
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.remove = fpwm_remove,
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};
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module_platform_driver(fpwm_driver);
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MODULE_AUTHOR("Pip Cet <pipcet@gmail.com>");
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MODULE_DESCRIPTION("PWM driver for Apple M1 FPWM");
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MODULE_ALIAS("platform:apple-m1-fpwm");
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MODULE_LICENSE("GPL");

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