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/*
* 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/export.h>
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/pwm.h>
#include <linux/module.h>
#include <linux/platform_data/omap-pwm.h>
#include <../arch/arm/plat-omap/include/plat/dmtimer.h>
#define DM_TIMER_LOAD_MIN 0xFFFFFFFE
struct omap_chip {
struct omap_dm_timer *dm_timer;
enum pwm_polarity polarity;
unsigned int duty_ns, period_ns;
struct pwm_chip chip;
};
#define to_omap_chip(chip) container_of(chip, struct omap_chip, chip)
/**
* pwm_calc_value - Determine the counter value for a clock rate and period.
* @clk_rate: The clock rate, in Hz, of the PWM's clock source to compute the
* counter value for.
* @ns: The period, in nanoseconds, to compute the counter value for.
*
* Returns the PWM counter value for the specified clock rate and period.
*/
static inline int pwm_calc_value(unsigned long clk_rate, int ns)
{
u64 c;
c = (u64)clk_rate * ns;
do_div(c, NSEC_PER_SEC);
return DM_TIMER_LOAD_MIN - c;
}
static int omap_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct omap_chip *omap = to_omap_chip(chip);
omap_dm_timer_start(omap->dm_timer);
return 0;
}
static void omap_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct omap_chip *omap = to_omap_chip(chip);
omap_dm_timer_stop(omap->dm_timer);
}
static int omap_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct omap_chip *omap = to_omap_chip(chip);
int load_value, match_value;
unsigned long clk_rate;
dev_dbg(chip->dev, "duty cycle: %d, period %d\n", duty_ns, period_ns);
if (omap->duty_ns == duty_ns &&
omap->period_ns == period_ns)
/* No change - don't cause any transients. */
return 0;
clk_rate = clk_get_rate(omap_dm_timer_get_fclk(omap->dm_timer));
/*
* 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_calc_value(clk_rate, period_ns);
match_value = pwm_calc_value(clk_rate, period_ns - duty_ns);
/*
* We MUST enable yet stop the associated dual-mode timer before
* attempting to write its registers. Hopefully it is already
* disabled, but call the (idempotent) pwm_disable just in case.
*/
pwm_disable(pwm);
omap_dm_timer_set_load(omap->dm_timer, true, load_value);
omap_dm_timer_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_dm_timer_set_pwm(omap->dm_timer,
omap->polarity == PWM_POLARITY_INVERSED,
true,
OMAP_TIMER_TRIGGER_OVERFLOW_AND_COMPARE);
omap->duty_ns = duty_ns;
omap->period_ns = period_ns;
return 0;
}
static int omap_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
enum pwm_polarity polarity)
{
struct omap_chip *omap = to_omap_chip(chip);
if (omap->polarity == polarity)
return 0;
omap->polarity = polarity;
omap_dm_timer_set_pwm(omap->dm_timer,
omap->polarity == PWM_POLARITY_INVERSED,
true,
OMAP_TIMER_TRIGGER_OVERFLOW_AND_COMPARE);
return 0;
}
static struct pwm_ops omap_pwm_ops = {
.enable = omap_pwm_enable,
.disable = omap_pwm_disable,
.config = omap_pwm_config,
.set_polarity = omap_pwm_set_polarity,
.owner = THIS_MODULE,
};
static int omap_pwm_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct omap_chip *omap;
int status = 0;
struct omap_pwm_pdata *pdata = dev->platform_data;
if (!pdata) {
dev_err(dev, "No platform data provided\n");
return -ENODEV;
}
omap = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
if (omap == NULL) {
dev_err(dev, "Could not allocate memory.\n");
return -ENOMEM;
}
if (pdata->mux_init != NULL) {
status = pdata->mux_init();
if (status < 0)
goto err_free;
}
/*
* Request the OMAP dual-mode timer that will be bound to and
* associated with this generic PWM.
*/
omap->dm_timer = omap_dm_timer_request_specific(pdata->timer_id);
if (omap->dm_timer == NULL) {
status = -EPROBE_DEFER;
goto err_free;
}
/*
* Configure the source for the dual-mode timer backing this
* generic PWM device. The clock source will ultimately determine
* how small or large the PWM frequency can be.
*
* At some point, it's probably worth revisiting moving this to
* the configure method and choosing either the slow- or
* system-clock source as appropriate for the desired PWM period.
*/
omap_dm_timer_set_source(omap->dm_timer, OMAP_TIMER_SRC_SYS_CLK);
/*
* Cache away other miscellaneous driver-private data and state
* information and add the driver-private data to the platform
* device.
*/
omap->chip.dev = dev;
omap->chip.ops = &omap_pwm_ops;
omap->chip.base = -1;
omap->chip.npwm = 1;
omap->polarity = PWM_POLARITY_NORMAL;
status = pwmchip_add(&omap->chip);
if (status < 0) {
dev_err(dev, "failed to register PWM\n");
omap_dm_timer_free(omap->dm_timer);
goto err_free;
}
platform_set_drvdata(pdev, omap);
return 0;
err_free:
kfree(omap);
return status;
}
static int omap_pwm_remove(struct platform_device *pdev)
{
struct omap_chip *omap = platform_get_drvdata(pdev);
int status;
omap_dm_timer_stop(omap->dm_timer);
status = pwmchip_remove(&omap->chip);
if (status < 0)
return status;
omap_dm_timer_free(omap->dm_timer);
kfree(omap);
return 0;
}
static struct platform_driver omap_pwm_driver = {
.driver = {
.name = "omap-pwm",
.owner = THIS_MODULE,
},
.probe = omap_pwm_probe,
.remove = omap_pwm_remove,
};
module_platform_driver(omap_pwm_driver);
MODULE_AUTHOR("Grant Erickson <marathon96@gmail.com>");
MODULE_AUTHOR("NeilBrown <neilb@suse.de>");
MODULE_LICENSE("GPL v2");
MODULE_VERSION("2012-12-01");
MODULE_DESCRIPTION("OMAP PWM Driver using Dual-mode Timers");
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