pwm: kona: Introduce Kona PWM controller support (6a4e4bff) · Commits · e / devices / android_kernel_teracube_2e

drivers/pwm/Kconfig

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		@@ -62,6 +62,15 @@ config PWM_ATMEL_TCB
		To compile this driver as a module, choose M here: the module
		will be called pwm-atmel-tcb.

		config PWM_BCM_KONA
		tristate "Kona PWM support"
		depends on ARCH_BCM_MOBILE
		help
		Generic PWM framework driver for Broadcom Kona PWM block.

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

		config PWM_BFIN
		tristate "Blackfin PWM support"
		depends on BFIN_GPTIMERS

drivers/pwm/Makefile

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		@@ -3,6 +3,7 @@ obj-$(CONFIG_PWM_SYSFS) += sysfs.o
		obj-$(CONFIG_PWM_AB8500) += pwm-ab8500.o
		obj-$(CONFIG_PWM_ATMEL) += pwm-atmel.o
		obj-$(CONFIG_PWM_ATMEL_TCB) += pwm-atmel-tcb.o
		obj-$(CONFIG_PWM_BCM_KONA) += pwm-bcm-kona.o
		obj-$(CONFIG_PWM_BFIN) += pwm-bfin.o
		obj-$(CONFIG_PWM_CLPS711X) += pwm-clps711x.o
		obj-$(CONFIG_PWM_EP93XX) += pwm-ep93xx.o

drivers/pwm/pwm-bcm-kona.c

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+318 −0

Original line number	Diff line number	Diff line
		/*
		* Copyright (C) 2014 Broadcom Corporation
		*
		* 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.
		*
		* This program is distributed "as is" WITHOUT ANY WARRANTY of any
		* kind, whether express or implied; without even the implied warranty
		* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
		* GNU General Public License for more details.
		*/

		#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);
		}

		static void kona_pwmc_apply_settings(struct kona_pwmc *kp, unsigned int chan)
		{
		unsigned int value = readl(kp->base + PWM_CONTROL_OFFSET);

		/* Clear trigger bit but set smooth bit to maintain old output */
		value \|= 1 << PWM_CONTROL_SMOOTH_SHIFT(chan);
		value &= ~(1 << PWM_CONTROL_TRIGGER_SHIFT(chan));
		writel(value, 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);
		}

		static int kona_pwmc_config(struct pwm_chip chip, struct pwm_device pwm,
		int duty_ns, int period_ns)
		{
		struct kona_pwmc *kp = to_kona_pwmc(chip);
		u64 val, 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;
		val = rate * period_ns;
		pc = div64_u64(val, div);
		val = rate * duty_ns;
		dc = div64_u64(val, div);

		/* If duty_ns or period_ns are not achievable then return */
		if (pc < PERIOD_COUNT_MIN \|\| dc < DUTY_CYCLE_HIGH_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;
		}

		/* If the PWM channel is enabled, write the settings to the HW */
		if (test_bit(PWMF_ENABLED, &pwm->flags)) {
		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;
		}

		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);

		/* Wait for waveform to settle before gating off the clock */
		ndelay(400);

		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;
		}

		ret = kona_pwmc_config(chip, pwm, pwm->duty_cycle, pwm->period);
		if (ret < 0) {
		clk_disable_unprepare(kp->clk);
		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;

		/* Simulate a disable by configuring for zero duty */
		writel(0, kp->base + DUTY_CYCLE_HIGH_OFFSET(chan));
		kona_pwmc_apply_settings(kp, chan);

		/* Wait for waveform to settle before gating off the clock */
		ndelay(400);

		clk_disable_unprepare(kp->clk);
		}

		static const struct pwm_ops kona_pwm_ops = {
		.config = kona_pwmc_config,
		.set_polarity = kona_pwmc_set_polarity,
		.enable = kona_pwmc_enable,
		.disable = kona_pwmc_disable,
		.owner = THIS_MODULE,
		};

		static int kona_pwmc_probe(struct platform_device *pdev)
		{
		struct kona_pwmc *kp;
		struct resource *res;
		unsigned int chan;
		unsigned int value = 0;
		int ret = 0;

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

		platform_set_drvdata(pdev, kp);

		kp->chip.dev = &pdev->dev;
		kp->chip.ops = &kona_pwm_ops;
		kp->chip.base = -1;
		kp->chip.npwm = 6;
		kp->chip.of_xlate = of_pwm_xlate_with_flags;
		kp->chip.of_pwm_n_cells = 3;
		kp->chip.can_sleep = true;

		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
		kp->base = devm_ioremap_resource(&pdev->dev, res);
		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 smooth mode, push/pull, and normal polarity for all channels */
		for (chan = 0; chan < kp->chip.npwm; chan++) {
		value \|= (1 << PWM_CONTROL_SMOOTH_SHIFT(chan));
		value \|= (1 << PWM_CONTROL_TYPE_SHIFT(chan));
		value \|= (1 << PWM_CONTROL_POLARITY_SHIFT(chan));
		}

		writel(value, kp->base + PWM_CONTROL_OFFSET);

		clk_disable_unprepare(kp->clk);

		ret = pwmchip_add(&kp->chip);
		if (ret < 0)
		dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);

		return ret;
		}

		static int kona_pwmc_remove(struct platform_device *pdev)
		{
		struct kona_pwmc *kp = platform_get_drvdata(pdev);
		unsigned int chan;

		for (chan = 0; chan < kp->chip.npwm; chan++)
		if (test_bit(PWMF_ENABLED, &kp->chip.pwms[chan].flags))
		clk_disable_unprepare(kp->clk);

		return pwmchip_remove(&kp->chip);
		}

		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,
		.remove = kona_pwmc_remove,
		};
		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");