pwm: Add PWM driver for OMAP using dual-mode timers (6604c655) · Commits · 戴 / test

Documentation/devicetree/bindings/pwm/pwm-omap-dmtimer.txt

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		* OMAP PWM for dual-mode timers

		Required properties:
		- compatible: Shall contain "ti,omap-dmtimer-pwm".
		- ti,timers: phandle to PWM capable OMAP timer. See arm/omap/timer.txt for info
		about these timers.
		- #pwm-cells: Should be 3. See pwm.txt in this directory for a description of
		the cells format.

		Optional properties:
		- ti,prescaler: Should be a value between 0 and 7, see the timers datasheet

		Example:
		pwm9: dmtimer-pwm@9 {
		compatible = "ti,omap-dmtimer-pwm";
		ti,timers = <&timer9>;
		#pwm-cells = <3>;
		};

drivers/pwm/Kconfig

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		@@ -265,6 +265,15 @@ config PWM_MXS
		To compile this driver as a module, choose M here: the module
		will be called pwm-mxs.

		config PWM_OMAP_DMTIMER
		tristate "OMAP Dual-Mode Timer PWM support"
		depends on OF && ARCH_OMAP && OMAP_DM_TIMER
		help
		Generic PWM framework driver for OMAP Dual-Mode Timer PWM output

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

		config PWM_PCA9685
		tristate "NXP PCA9685 PWM driver"
		depends on I2C

drivers/pwm/Makefile

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		@@ -24,6 +24,7 @@ obj-$(CONFIG_PWM_LPSS_PCI) += pwm-lpss-pci.o
		obj-$(CONFIG_PWM_LPSS_PLATFORM) += pwm-lpss-platform.o
		obj-$(CONFIG_PWM_MTK_DISP) += pwm-mtk-disp.o
		obj-$(CONFIG_PWM_MXS) += pwm-mxs.o
		obj-$(CONFIG_PWM_OMAP_DMTIMER) += pwm-omap-dmtimer.o
		obj-$(CONFIG_PWM_PCA9685) += pwm-pca9685.o
		obj-$(CONFIG_PWM_PUV3) += pwm-puv3.o
		obj-$(CONFIG_PWM_PXA) += pwm-pxa.o

drivers/pwm/pwm-omap-dmtimer.c

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		/*
		* Copyright (c) 2015 Neil Armstrong <narmstrong@baylibre.com>
		* Copyright (c) 2014 Joachim Eastwood <manabian@gmail.com>
		* Copyright (c) 2012 NeilBrown <neilb@suse.de>
		* Heavily based on earlier code which is:
		* Copyright (c) 2010 Grant Erickson <marathon96@gmail.com>
		*
		* Also based on pwm-samsung.c
		*
		* This program is free software; you can redistribute it and/or
		* modify it under the terms of the GNU General Public License
		* version 2 as published by the Free Software Foundation.
		*
		* Description:
		* This file is the core OMAP support for the generic, Linux
		* PWM driver / controller, using the OMAP's dual-mode timers.
		*/

		#include <linux/clk.h>
		#include <linux/err.h>
		#include <linux/kernel.h>
		#include <linux/module.h>
		#include <linux/mutex.h>
		#include <linux/of.h>
		#include <linux/of_platform.h>
		#include <linux/platform_data/pwm_omap_dmtimer.h>
		#include <linux/platform_device.h>
		#include <linux/pm_runtime.h>
		#include <linux/pwm.h>
		#include <linux/slab.h>
		#include <linux/time.h>

		#define DM_TIMER_LOAD_MIN 0xfffffffe

		struct pwm_omap_dmtimer_chip {
		struct pwm_chip chip;
		struct mutex mutex;
		pwm_omap_dmtimer *dm_timer;
		struct pwm_omap_dmtimer_pdata *pdata;
		struct platform_device *dm_timer_pdev;
		};

		static inline struct pwm_omap_dmtimer_chip *
		to_pwm_omap_dmtimer_chip(struct pwm_chip *chip)
		{
		return container_of(chip, struct pwm_omap_dmtimer_chip, chip);
		}

		static int pwm_omap_dmtimer_calc_value(unsigned long clk_rate, int ns)
		{
		u64 c = (u64)clk_rate * ns;

		do_div(c, NSEC_PER_SEC);

		return DM_TIMER_LOAD_MIN - c;
		}

		static void pwm_omap_dmtimer_start(struct pwm_omap_dmtimer_chip *omap)
		{
		/*
		* According to OMAP 4 TRM section 22.2.4.10 the counter should be
		* started at 0xFFFFFFFE when overflow and match is used to ensure
		* that the PWM line is toggled on the first event.
		*
		* Note that omap_dm_timer_enable/disable is for register access and
		* not the timer counter itself.
		*/
		omap->pdata->enable(omap->dm_timer);
		omap->pdata->write_counter(omap->dm_timer, DM_TIMER_LOAD_MIN);
		omap->pdata->disable(omap->dm_timer);

		omap->pdata->start(omap->dm_timer);
		}

		static int pwm_omap_dmtimer_enable(struct pwm_chip *chip,
		struct pwm_device *pwm)
		{
		struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);

		mutex_lock(&omap->mutex);
		pwm_omap_dmtimer_start(omap);
		mutex_unlock(&omap->mutex);

		return 0;
		}

		static void pwm_omap_dmtimer_disable(struct pwm_chip *chip,
		struct pwm_device *pwm)
		{
		struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);

		mutex_lock(&omap->mutex);
		omap->pdata->stop(omap->dm_timer);
		mutex_unlock(&omap->mutex);
		}

		static int pwm_omap_dmtimer_config(struct pwm_chip *chip,
		struct pwm_device *pwm,
		int duty_ns, int period_ns)
		{
		struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);
		int load_value, match_value;
		struct clk *fclk;
		unsigned long clk_rate;
		bool timer_active;

		dev_dbg(chip->dev, "duty cycle: %d, period %d\n", duty_ns, period_ns);

		mutex_lock(&omap->mutex);
		if (duty_ns == pwm_get_duty_cycle(pwm) &&
		period_ns == pwm_get_period(pwm)) {
		/* No change - don't cause any transients. */
		mutex_unlock(&omap->mutex);
		return 0;
		}

		fclk = omap->pdata->get_fclk(omap->dm_timer);
		if (!fclk) {
		dev_err(chip->dev, "invalid pmtimer fclk\n");
		mutex_unlock(&omap->mutex);
		return -EINVAL;
		}

		clk_rate = clk_get_rate(fclk);
		if (!clk_rate) {
		dev_err(chip->dev, "invalid pmtimer fclk rate\n");
		mutex_unlock(&omap->mutex);
		return -EINVAL;
		}

		dev_dbg(chip->dev, "clk rate: %luHz\n", clk_rate);

		/*
		* Calculate the appropriate load and match values based on the
		* specified period and duty cycle. The load value determines the
		* cycle time and the match value determines the duty cycle.
		*/
		load_value = pwm_omap_dmtimer_calc_value(clk_rate, period_ns);
		match_value = pwm_omap_dmtimer_calc_value(clk_rate,
		period_ns - duty_ns);

		/*
		* We MUST stop the associated dual-mode timer before attempting to
		* write its registers, but calls to omap_dm_timer_start/stop must
		* be balanced so check if timer is active before calling timer_stop.
		*/
		timer_active = pm_runtime_active(&omap->dm_timer_pdev->dev);
		if (timer_active)
		omap->pdata->stop(omap->dm_timer);

		omap->pdata->set_load(omap->dm_timer, true, load_value);
		omap->pdata->set_match(omap->dm_timer, true, match_value);

		dev_dbg(chip->dev, "load value: %#08x (%d), match value: %#08x (%d)\n",
		load_value, load_value, match_value, match_value);

		omap->pdata->set_pwm(omap->dm_timer,
		pwm->polarity == PWM_POLARITY_INVERSED,
		true,
		PWM_OMAP_DMTIMER_TRIGGER_OVERFLOW_AND_COMPARE);

		/* If config was called while timer was running it must be reenabled. */
		if (timer_active)
		pwm_omap_dmtimer_start(omap);

		mutex_unlock(&omap->mutex);

		return 0;
		}

		static int pwm_omap_dmtimer_set_polarity(struct pwm_chip *chip,
		struct pwm_device *pwm,
		enum pwm_polarity polarity)
		{
		struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);

		/*
		* PWM core will not call set_polarity while PWM is enabled so it's
		* safe to reconfigure the timer here without stopping it first.
		*/
		mutex_lock(&omap->mutex);
		omap->pdata->set_pwm(omap->dm_timer,
		polarity == PWM_POLARITY_INVERSED,
		true,
		PWM_OMAP_DMTIMER_TRIGGER_OVERFLOW_AND_COMPARE);
		mutex_unlock(&omap->mutex);

		return 0;
		}

		static const struct pwm_ops pwm_omap_dmtimer_ops = {
		.enable = pwm_omap_dmtimer_enable,
		.disable = pwm_omap_dmtimer_disable,
		.config = pwm_omap_dmtimer_config,
		.set_polarity = pwm_omap_dmtimer_set_polarity,
		.owner = THIS_MODULE,
		};

		static int pwm_omap_dmtimer_probe(struct platform_device *pdev)
		{
		struct device_node *np = pdev->dev.of_node;
		struct device_node *timer;
		struct pwm_omap_dmtimer_chip *omap;
		struct pwm_omap_dmtimer_pdata *pdata;
		pwm_omap_dmtimer *dm_timer;
		u32 prescaler;
		int status;

		pdata = dev_get_platdata(&pdev->dev);
		if (!pdata) {
		dev_err(&pdev->dev, "Missing dmtimer platform data\n");
		return -EINVAL;
		}

		if (!pdata->request_by_node \|\|
		!pdata->free \|\|
		!pdata->enable \|\|
		!pdata->disable \|\|
		!pdata->get_fclk \|\|
		!pdata->start \|\|
		!pdata->stop \|\|
		!pdata->set_load \|\|
		!pdata->set_match \|\|
		!pdata->set_pwm \|\|
		!pdata->set_prescaler \|\|
		!pdata->write_counter) {
		dev_err(&pdev->dev, "Incomplete dmtimer pdata structure\n");
		return -EINVAL;
		}

		timer = of_parse_phandle(np, "ti,timers", 0);
		if (!timer)
		return -ENODEV;

		if (!of_get_property(timer, "ti,timer-pwm", NULL)) {
		dev_err(&pdev->dev, "Missing ti,timer-pwm capability\n");
		return -ENODEV;
		}

		dm_timer = pdata->request_by_node(timer);
		if (!dm_timer)
		return -EPROBE_DEFER;

		omap = devm_kzalloc(&pdev->dev, sizeof(*omap), GFP_KERNEL);
		if (!omap) {
		omap->pdata->free(dm_timer);
		return -ENOMEM;
		}

		omap->pdata = pdata;
		omap->dm_timer = dm_timer;

		omap->dm_timer_pdev = of_find_device_by_node(timer);
		if (!omap->dm_timer_pdev) {
		dev_err(&pdev->dev, "Unable to find timer pdev\n");
		omap->pdata->free(dm_timer);
		return -EINVAL;
		}

		/*
		* Ensure that the timer is stopped before we allow PWM core to call
		* pwm_enable.
		*/
		if (pm_runtime_active(&omap->dm_timer_pdev->dev))
		omap->pdata->stop(omap->dm_timer);

		/* setup dmtimer prescaler */
		if (!of_property_read_u32(pdev->dev.of_node, "ti,prescaler",
		&prescaler))
		omap->pdata->set_prescaler(omap->dm_timer, prescaler);

		omap->chip.dev = &pdev->dev;
		omap->chip.ops = &pwm_omap_dmtimer_ops;
		omap->chip.base = -1;
		omap->chip.npwm = 1;
		omap->chip.of_xlate = of_pwm_xlate_with_flags;
		omap->chip.of_pwm_n_cells = 3;

		mutex_init(&omap->mutex);

		status = pwmchip_add(&omap->chip);
		if (status < 0) {
		dev_err(&pdev->dev, "failed to register PWM\n");
		omap->pdata->free(omap->dm_timer);
		return status;
		}

		platform_set_drvdata(pdev, omap);

		return 0;
		}

		static int pwm_omap_dmtimer_remove(struct platform_device *pdev)
		{
		struct pwm_omap_dmtimer_chip *omap = platform_get_drvdata(pdev);

		if (pm_runtime_active(&omap->dm_timer_pdev->dev))
		omap->pdata->stop(omap->dm_timer);

		omap->pdata->free(omap->dm_timer);

		mutex_destroy(&omap->mutex);

		return pwmchip_remove(&omap->chip);
		}

		static const struct of_device_id pwm_omap_dmtimer_of_match[] = {
		{.compatible = "ti,omap-dmtimer-pwm"},
		{}
		};
		MODULE_DEVICE_TABLE(of, pwm_omap_dmtimer_of_match);

		static struct platform_driver pwm_omap_dmtimer_driver = {
		.driver = {
		.name = "omap-dmtimer-pwm",
		.of_match_table = of_match_ptr(pwm_omap_dmtimer_of_match),
		},
		.probe = pwm_omap_dmtimer_probe,
		.remove = pwm_omap_dmtimer_remove,
		};
		module_platform_driver(pwm_omap_dmtimer_driver);

		MODULE_AUTHOR("Grant Erickson <marathon96@gmail.com>");
		MODULE_AUTHOR("NeilBrown <neilb@suse.de>");
		MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
		MODULE_LICENSE("GPL v2");
		MODULE_DESCRIPTION("OMAP PWM Driver using Dual-mode Timers");

include/linux/platform_data/pwm_omap_dmtimer.h

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		/*
		* include/linux/platform_data/pwm_omap_dmtimer.h
		*
		* OMAP Dual-Mode Timer PWM platform data
		*
		* Copyright (C) 2010 Texas Instruments Incorporated - http://www.ti.com/
		* Tarun Kanti DebBarma <tarun.kanti@ti.com>
		* Thara Gopinath <thara@ti.com>
		*
		* Platform device conversion and hwmod support.
		*
		* Copyright (C) 2005 Nokia Corporation
		* Author: Lauri Leukkunen <lauri.leukkunen@nokia.com>
		* PWM and clock framework support by Timo Teras.
		*
		* 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; either version 2 of the License, or (at your
		* option) any later version.
		*
		* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
		* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
		* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
		* NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
		* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
		* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
		* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
		* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
		*
		* You should have received a copy of the GNU General Public License along
		* with this program; if not, write to the Free Software Foundation, Inc.,
		* 675 Mass Ave, Cambridge, MA 02139, USA.
		*/

		#ifndef __PWM_OMAP_DMTIMER_PDATA_H
		#define __PWM_OMAP_DMTIMER_PDATA_H

		/* trigger types */
		#define PWM_OMAP_DMTIMER_TRIGGER_NONE 0x00
		#define PWM_OMAP_DMTIMER_TRIGGER_OVERFLOW 0x01
		#define PWM_OMAP_DMTIMER_TRIGGER_OVERFLOW_AND_COMPARE 0x02

		struct omap_dm_timer;
		typedef struct omap_dm_timer pwm_omap_dmtimer;

		struct pwm_omap_dmtimer_pdata {
		pwm_omap_dmtimer (request_by_node)(struct device_node *np);
		int (free)(pwm_omap_dmtimer timer);

		void (enable)(pwm_omap_dmtimer timer);
		void (disable)(pwm_omap_dmtimer timer);

		struct clk (get_fclk)(pwm_omap_dmtimer *timer);

		int (start)(pwm_omap_dmtimer timer);
		int (stop)(pwm_omap_dmtimer timer);

		int (set_load)(pwm_omap_dmtimer timer, int autoreload,
		unsigned int value);
		int (set_match)(pwm_omap_dmtimer timer, int enable,
		unsigned int match);
		int (set_pwm)(pwm_omap_dmtimer timer, int def_on,
		int toggle, int trigger);
		int (set_prescaler)(pwm_omap_dmtimer timer, int prescaler);

		int (write_counter)(pwm_omap_dmtimer timer, unsigned int value);
		};

		#endif /* __PWM_OMAP_DMTIMER_PDATA_H */

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