pwm: Add BCM2835 PWM driver (e5a06dc5) · Commits · e / devices / android_kernel_samsung_universal8895

Documentation/devicetree/bindings/pwm/pwm-bcm2835.txt

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			BCM2835 PWM controller (Raspberry Pi controller)

			Required properties:
			- compatible: should be "brcm,bcm2835-pwm"
			- reg: physical base address and length of the controller's registers
			- clock: This clock defines the base clock frequency of the PWM hardware
			system, the period and the duty_cycle of the PWM signal is a multiple of
			the base period.
			- #pwm-cells: Should be 2. See pwm.txt in this directory for a description of
			the cells format.

			Examples:

			pwm@2020c000 {
			compatible = "brcm,bcm2835-pwm";
			reg = <0x2020c000 0x28>;
			clocks = <&clk_pwm>;
			#pwm-cells = <2>;
			};

			clocks {
			....
			clk_pwm: pwm {
			compatible = "fixed-clock";
			reg = <3>;
			#clock-cells = <0>;
			clock-frequency = <9200000>;
			};
			....
			};

drivers/pwm/Kconfig

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	@@ -71,6 +71,15 @@ config PWM_BCM_KONA
	To compile this driver as a module, choose M here: the module		To compile this driver as a module, choose M here: the module
	will be called pwm-bcm-kona.		will be called pwm-bcm-kona.

			config PWM_BCM2835
			tristate "BCM2835 PWM support"
			depends on ARCH_BCM2835
			help
			PWM framework driver for BCM2835 controller (Raspberry Pi)

			To compile this driver as a module, choose M here: the module
			will be called pwm-bcm2835.

	config PWM_BFIN		config PWM_BFIN
	tristate "Blackfin PWM support"		tristate "Blackfin PWM support"
	depends on BFIN_GPTIMERS		depends on BFIN_GPTIMERS

drivers/pwm/Makefile

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	@@ -4,6 +4,7 @@ obj-$(CONFIG_PWM_AB8500) += pwm-ab8500.o
	obj-$(CONFIG_PWM_ATMEL) += pwm-atmel.o		obj-$(CONFIG_PWM_ATMEL) += pwm-atmel.o
	obj-$(CONFIG_PWM_ATMEL_TCB) += pwm-atmel-tcb.o		obj-$(CONFIG_PWM_ATMEL_TCB) += pwm-atmel-tcb.o
	obj-$(CONFIG_PWM_BCM_KONA) += pwm-bcm-kona.o		obj-$(CONFIG_PWM_BCM_KONA) += pwm-bcm-kona.o
			obj-$(CONFIG_PWM_BCM2835) += pwm-bcm2835.o
	obj-$(CONFIG_PWM_BFIN) += pwm-bfin.o		obj-$(CONFIG_PWM_BFIN) += pwm-bfin.o
	obj-$(CONFIG_PWM_CLPS711X) += pwm-clps711x.o		obj-$(CONFIG_PWM_CLPS711X) += pwm-clps711x.o
	obj-$(CONFIG_PWM_EP93XX) += pwm-ep93xx.o		obj-$(CONFIG_PWM_EP93XX) += pwm-ep93xx.o

drivers/pwm/pwm-bcm2835.c

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			/*
			* Copyright 2014 Bart Tanghe <bart.tanghe@thomasmore.be>
			*
			* This program is free software; you can redistribute it and/or modify
			* it under the terms of the GNU General Public License as published by
			* the Free Software Foundation; version 2.
			*/

			#include <linux/clk.h>
			#include <linux/err.h>
			#include <linux/io.h>
			#include <linux/module.h>
			#include <linux/of.h>
			#include <linux/platform_device.h>
			#include <linux/pwm.h>

			#define PWM_CONTROL 0x000
			#define PWM_CONTROL_SHIFT(x) ((x) * 8)
			#define PWM_CONTROL_MASK 0xff
			#define PWM_MODE 0x80 /* set timer in PWM mode */
			#define PWM_ENABLE (1 << 0)
			#define PWM_POLARITY (1 << 4)

			#define PERIOD(x) (((x) * 0x10) + 0x10)
			#define DUTY(x) (((x) * 0x10) + 0x14)

			#define MIN_PERIOD 108 /* 9.2 MHz max. PWM clock */

			struct bcm2835_pwm {
			struct pwm_chip chip;
			struct device *dev;
			unsigned long scaler;
			void __iomem *base;
			struct clk *clk;
			};

			static inline struct bcm2835_pwm to_bcm2835_pwm(struct pwm_chip chip)
			{
			return container_of(chip, struct bcm2835_pwm, chip);
			}

			static int bcm2835_pwm_request(struct pwm_chip chip, struct pwm_device pwm)
			{
			struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
			u32 value;

			value = readl(pc->base + PWM_CONTROL);
			value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
			value \|= (PWM_MODE << PWM_CONTROL_SHIFT(pwm->hwpwm));
			writel(value, pc->base + PWM_CONTROL);

			return 0;
			}

			static void bcm2835_pwm_free(struct pwm_chip chip, struct pwm_device pwm)
			{
			struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
			u32 value;

			value = readl(pc->base + PWM_CONTROL);
			value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
			writel(value, pc->base + PWM_CONTROL);
			}

			static int bcm2835_pwm_config(struct pwm_chip chip, struct pwm_device pwm,
			int duty_ns, int period_ns)
			{
			struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);

			if (period_ns <= MIN_PERIOD) {
			dev_err(pc->dev, "period %d not supported, minimum %d\n",
			period_ns, MIN_PERIOD);
			return -EINVAL;
			}

			writel(duty_ns / pc->scaler, pc->base + DUTY(pwm->hwpwm));
			writel(period_ns / pc->scaler, pc->base + PERIOD(pwm->hwpwm));

			return 0;
			}

			static int bcm2835_pwm_enable(struct pwm_chip chip, struct pwm_device pwm)
			{
			struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
			u32 value;

			value = readl(pc->base + PWM_CONTROL);
			value \|= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
			writel(value, pc->base + PWM_CONTROL);

			return 0;
			}

			static void bcm2835_pwm_disable(struct pwm_chip chip, struct pwm_device pwm)
			{
			struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
			u32 value;

			value = readl(pc->base + PWM_CONTROL);
			value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
			writel(value, pc->base + PWM_CONTROL);
			}

			static int bcm2835_set_polarity(struct pwm_chip chip, struct pwm_device pwm,
			enum pwm_polarity polarity)
			{
			struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
			u32 value;

			value = readl(pc->base + PWM_CONTROL);

			if (polarity == PWM_POLARITY_NORMAL)
			value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
			else
			value \|= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);

			writel(value, pc->base + PWM_CONTROL);

			return 0;
			}

			static const struct pwm_ops bcm2835_pwm_ops = {
			.request = bcm2835_pwm_request,
			.free = bcm2835_pwm_free,
			.config = bcm2835_pwm_config,
			.enable = bcm2835_pwm_enable,
			.disable = bcm2835_pwm_disable,
			.set_polarity = bcm2835_set_polarity,
			.owner = THIS_MODULE,
			};

			static int bcm2835_pwm_probe(struct platform_device *pdev)
			{
			struct bcm2835_pwm *pc;
			struct resource *res;
			int ret;

			pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
			if (!pc)
			return -ENOMEM;

			pc->dev = &pdev->dev;

			res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
			pc->base = devm_ioremap_resource(&pdev->dev, res);
			if (IS_ERR(pc->base))
			return PTR_ERR(pc->base);

			pc->clk = devm_clk_get(&pdev->dev, NULL);
			if (IS_ERR(pc->clk)) {
			dev_err(&pdev->dev, "clock not found: %ld\n", PTR_ERR(pc->clk));
			return PTR_ERR(pc->clk);
			}

			ret = clk_prepare_enable(pc->clk);
			if (ret)
			return ret;

			pc->scaler = NSEC_PER_SEC / clk_get_rate(pc->clk);

			pc->chip.dev = &pdev->dev;
			pc->chip.ops = &bcm2835_pwm_ops;
			pc->chip.npwm = 2;

			platform_set_drvdata(pdev, pc);

			ret = pwmchip_add(&pc->chip);
			if (ret < 0)
			goto add_fail;

			return 0;

			add_fail:
			clk_disable_unprepare(pc->clk);
			return ret;
			}

			static int bcm2835_pwm_remove(struct platform_device *pdev)
			{
			struct bcm2835_pwm *pc = platform_get_drvdata(pdev);

			clk_disable_unprepare(pc->clk);

			return pwmchip_remove(&pc->chip);
			}

			static const struct of_device_id bcm2835_pwm_of_match[] = {
			{ .compatible = "brcm,bcm2835-pwm", },
			{ /* sentinel */ }
			};
			MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match);

			static struct platform_driver bcm2835_pwm_driver = {
			.driver = {
			.name = "bcm2835-pwm",
			.of_match_table = bcm2835_pwm_of_match,
			},
			.probe = bcm2835_pwm_probe,
			.remove = bcm2835_pwm_remove,
			};
			module_platform_driver(bcm2835_pwm_driver);

			MODULE_AUTHOR("Bart Tanghe <bart.tanghe@thomasmore.be");
			MODULE_DESCRIPTION("Broadcom BCM2835 PWM driver");
			MODULE_LICENSE("GPL v2");