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pwm: Add PWM driver for OMAP using dual-mode timers

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Adds support for using a OMAP dual-mode timer with PWM capability
as a Linux PWM device. The driver controls the timer by using the
dmtimer API.

Add a platform_data structure for each pwm-omap-dmtimer nodes containing
the dmtimers functions in order to get driver not rely on platform
specific functions.

Cc: Grant Erickson <marathon96@gmail.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Joachim Eastwood <manabian@gmail.com>
Suggested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Tony Lindgren <tony@atomide.com>
[thierry.reding@gmail.com: coding style bikeshed, fix timer leak]
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
This commit is contained in:
Neil Armstrong 2015-11-02 12:14:21 +01:00 committed by Thierry Reding
parent 72c16a9f98
commit 6604c6556d
5 changed files with 424 additions and 0 deletions
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18
Documentation/devicetree/bindings/pwm/pwm-omap-dmtimer.txt Normal file
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@ -0,0 +1,18 @@
* 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>;
};

9
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

1
drivers/pwm/Makefile
View file

@ -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

327
drivers/pwm/pwm-omap-dmtimer.c Normal file
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@ -0,0 +1,327 @@
/*
* 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");

69
include/linux/platform_data/pwm_omap_dmtimer.h Normal file
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@ -0,0 +1,69 @@
/*
* 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 */