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+/*
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+ * Copyright (c) 2015 Neil Armstrong <narmstrong@baylibre.com>
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+ * Copyright (c) 2014 Joachim Eastwood <manabian@gmail.com>
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+ * Copyright (c) 2012 NeilBrown <neilb@suse.de>
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+ * Heavily based on earlier code which is:
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+ * Copyright (c) 2010 Grant Erickson <marathon96@gmail.com>
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+ *
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+ * Also based on pwm-samsung.c
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+ *
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+ * This program is free software; you can redistribute it and/or
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+ * modify it under the terms of the GNU General Public License
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+ * version 2 as published by the Free Software Foundation.
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+ *
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+ * Description:
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+ * This file is the core OMAP support for the generic, Linux
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+ * PWM driver / controller, using the OMAP's dual-mode timers.
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+ */
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+
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+#include <linux/clk.h>
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+#include <linux/err.h>
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+#include <linux/kernel.h>
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+#include <linux/module.h>
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+#include <linux/mutex.h>
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+#include <linux/of.h>
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+#include <linux/of_platform.h>
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+#include <linux/platform_data/pwm_omap_dmtimer.h>
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+#include <linux/platform_device.h>
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+#include <linux/pm_runtime.h>
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+#include <linux/pwm.h>
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+#include <linux/slab.h>
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+#include <linux/time.h>
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+
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+#define DM_TIMER_LOAD_MIN 0xfffffffe
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+
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+struct pwm_omap_dmtimer_chip {
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+ struct pwm_chip chip;
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+ struct mutex mutex;
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+ pwm_omap_dmtimer *dm_timer;
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+ struct pwm_omap_dmtimer_pdata *pdata;
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+ struct platform_device *dm_timer_pdev;
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+};
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+
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+static inline struct pwm_omap_dmtimer_chip *
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+to_pwm_omap_dmtimer_chip(struct pwm_chip *chip)
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+{
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+ return container_of(chip, struct pwm_omap_dmtimer_chip, chip);
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+}
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+
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+static int pwm_omap_dmtimer_calc_value(unsigned long clk_rate, int ns)
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+{
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+ u64 c = (u64)clk_rate * ns;
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+
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+ do_div(c, NSEC_PER_SEC);
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+
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+ return DM_TIMER_LOAD_MIN - c;
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+}
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+
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+static void pwm_omap_dmtimer_start(struct pwm_omap_dmtimer_chip *omap)
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+{
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+ /*
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+ * According to OMAP 4 TRM section 22.2.4.10 the counter should be
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+ * started at 0xFFFFFFFE when overflow and match is used to ensure
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+ * that the PWM line is toggled on the first event.
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+ *
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+ * Note that omap_dm_timer_enable/disable is for register access and
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+ * not the timer counter itself.
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+ */
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+ omap->pdata->enable(omap->dm_timer);
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+ omap->pdata->write_counter(omap->dm_timer, DM_TIMER_LOAD_MIN);
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+ omap->pdata->disable(omap->dm_timer);
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+
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+ omap->pdata->start(omap->dm_timer);
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+}
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+
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+static int pwm_omap_dmtimer_enable(struct pwm_chip *chip,
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+ struct pwm_device *pwm)
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+{
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+ struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);
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+
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+ mutex_lock(&omap->mutex);
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+ pwm_omap_dmtimer_start(omap);
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+ mutex_unlock(&omap->mutex);
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+
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+ return 0;
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+}
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+
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+static void pwm_omap_dmtimer_disable(struct pwm_chip *chip,
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+ struct pwm_device *pwm)
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+{
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+ struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);
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+
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+ mutex_lock(&omap->mutex);
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+ omap->pdata->stop(omap->dm_timer);
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+ mutex_unlock(&omap->mutex);
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+}
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+
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+static int pwm_omap_dmtimer_config(struct pwm_chip *chip,
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+ struct pwm_device *pwm,
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+ int duty_ns, int period_ns)
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+{
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+ struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);
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+ int load_value, match_value;
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+ struct clk *fclk;
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+ unsigned long clk_rate;
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+ bool timer_active;
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+
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+ dev_dbg(chip->dev, "duty cycle: %d, period %d\n", duty_ns, period_ns);
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+
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+ mutex_lock(&omap->mutex);
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+ if (duty_ns == pwm_get_duty_cycle(pwm) &&
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+ period_ns == pwm_get_period(pwm)) {
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+ /* No change - don't cause any transients. */
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+ mutex_unlock(&omap->mutex);
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+ return 0;
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+ }
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+
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+ fclk = omap->pdata->get_fclk(omap->dm_timer);
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+ if (!fclk) {
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+ dev_err(chip->dev, "invalid pmtimer fclk\n");
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+ mutex_unlock(&omap->mutex);
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+ return -EINVAL;
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+ }
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+
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+ clk_rate = clk_get_rate(fclk);
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+ if (!clk_rate) {
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+ dev_err(chip->dev, "invalid pmtimer fclk rate\n");
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+ mutex_unlock(&omap->mutex);
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+ return -EINVAL;
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+ }
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+
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+ dev_dbg(chip->dev, "clk rate: %luHz\n", clk_rate);
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+
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+ /*
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+ * Calculate the appropriate load and match values based on the
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+ * specified period and duty cycle. The load value determines the
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+ * cycle time and the match value determines the duty cycle.
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+ */
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+ load_value = pwm_omap_dmtimer_calc_value(clk_rate, period_ns);
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+ match_value = pwm_omap_dmtimer_calc_value(clk_rate,
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+ period_ns - duty_ns);
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+
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+ /*
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+ * We MUST stop the associated dual-mode timer before attempting to
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+ * write its registers, but calls to omap_dm_timer_start/stop must
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+ * be balanced so check if timer is active before calling timer_stop.
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+ */
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+ timer_active = pm_runtime_active(&omap->dm_timer_pdev->dev);
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+ if (timer_active)
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+ omap->pdata->stop(omap->dm_timer);
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+
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+ omap->pdata->set_load(omap->dm_timer, true, load_value);
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+ omap->pdata->set_match(omap->dm_timer, true, match_value);
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+
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+ dev_dbg(chip->dev, "load value: %#08x (%d), match value: %#08x (%d)\n",
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+ load_value, load_value, match_value, match_value);
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+
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+ omap->pdata->set_pwm(omap->dm_timer,
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+ pwm->polarity == PWM_POLARITY_INVERSED,
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+ true,
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+ PWM_OMAP_DMTIMER_TRIGGER_OVERFLOW_AND_COMPARE);
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+
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+ /* If config was called while timer was running it must be reenabled. */
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+ if (timer_active)
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+ pwm_omap_dmtimer_start(omap);
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+
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+ mutex_unlock(&omap->mutex);
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+
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+ return 0;
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+}
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+
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+static int pwm_omap_dmtimer_set_polarity(struct pwm_chip *chip,
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+ struct pwm_device *pwm,
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+ enum pwm_polarity polarity)
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+{
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+ struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);
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+
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+ /*
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+ * PWM core will not call set_polarity while PWM is enabled so it's
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+ * safe to reconfigure the timer here without stopping it first.
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+ */
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+ mutex_lock(&omap->mutex);
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+ omap->pdata->set_pwm(omap->dm_timer,
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+ polarity == PWM_POLARITY_INVERSED,
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+ true,
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+ PWM_OMAP_DMTIMER_TRIGGER_OVERFLOW_AND_COMPARE);
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+ mutex_unlock(&omap->mutex);
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+
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+ return 0;
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+}
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+
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+static const struct pwm_ops pwm_omap_dmtimer_ops = {
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+ .enable = pwm_omap_dmtimer_enable,
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+ .disable = pwm_omap_dmtimer_disable,
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+ .config = pwm_omap_dmtimer_config,
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+ .set_polarity = pwm_omap_dmtimer_set_polarity,
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+ .owner = THIS_MODULE,
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+};
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+
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+static int pwm_omap_dmtimer_probe(struct platform_device *pdev)
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+{
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+ struct device_node *np = pdev->dev.of_node;
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+ struct device_node *timer;
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+ struct pwm_omap_dmtimer_chip *omap;
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+ struct pwm_omap_dmtimer_pdata *pdata;
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+ pwm_omap_dmtimer *dm_timer;
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+ u32 prescaler;
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+ int status;
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+
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+ pdata = dev_get_platdata(&pdev->dev);
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+ if (!pdata) {
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+ dev_err(&pdev->dev, "Missing dmtimer platform data\n");
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+ return -EINVAL;
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+ }
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+
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+ if (!pdata->request_by_node ||
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+ !pdata->free ||
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+ !pdata->enable ||
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+ !pdata->disable ||
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+ !pdata->get_fclk ||
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+ !pdata->start ||
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+ !pdata->stop ||
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+ !pdata->set_load ||
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+ !pdata->set_match ||
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+ !pdata->set_pwm ||
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+ !pdata->set_prescaler ||
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+ !pdata->write_counter) {
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+ dev_err(&pdev->dev, "Incomplete dmtimer pdata structure\n");
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+ return -EINVAL;
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+ }
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+
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+ timer = of_parse_phandle(np, "ti,timers", 0);
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+ if (!timer)
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+ return -ENODEV;
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+
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+ if (!of_get_property(timer, "ti,timer-pwm", NULL)) {
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+ dev_err(&pdev->dev, "Missing ti,timer-pwm capability\n");
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+ return -ENODEV;
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+ }
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+
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+ dm_timer = pdata->request_by_node(timer);
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+ if (!dm_timer)
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+ return -EPROBE_DEFER;
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+
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+ omap = devm_kzalloc(&pdev->dev, sizeof(*omap), GFP_KERNEL);
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+ if (!omap) {
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+ pdata->free(dm_timer);
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+ return -ENOMEM;
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+ }
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+
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+ omap->pdata = pdata;
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+ omap->dm_timer = dm_timer;
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+
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+ omap->dm_timer_pdev = of_find_device_by_node(timer);
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+ if (!omap->dm_timer_pdev) {
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+ dev_err(&pdev->dev, "Unable to find timer pdev\n");
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+ omap->pdata->free(dm_timer);
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+ return -EINVAL;
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+ }
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+
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+ /*
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+ * Ensure that the timer is stopped before we allow PWM core to call
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+ * pwm_enable.
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+ */
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+ if (pm_runtime_active(&omap->dm_timer_pdev->dev))
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+ omap->pdata->stop(omap->dm_timer);
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+
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+ /* setup dmtimer prescaler */
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+ if (!of_property_read_u32(pdev->dev.of_node, "ti,prescaler",
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+ &prescaler))
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+ omap->pdata->set_prescaler(omap->dm_timer, prescaler);
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+
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+ omap->chip.dev = &pdev->dev;
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+ omap->chip.ops = &pwm_omap_dmtimer_ops;
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+ omap->chip.base = -1;
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+ omap->chip.npwm = 1;
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+ omap->chip.of_xlate = of_pwm_xlate_with_flags;
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+ omap->chip.of_pwm_n_cells = 3;
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+
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+ mutex_init(&omap->mutex);
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+
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+ status = pwmchip_add(&omap->chip);
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+ if (status < 0) {
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+ dev_err(&pdev->dev, "failed to register PWM\n");
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+ omap->pdata->free(omap->dm_timer);
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+ return status;
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+ }
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+
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+ platform_set_drvdata(pdev, omap);
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+
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+ return 0;
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+}
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+
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+static int pwm_omap_dmtimer_remove(struct platform_device *pdev)
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+{
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+ struct pwm_omap_dmtimer_chip *omap = platform_get_drvdata(pdev);
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+
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+ if (pm_runtime_active(&omap->dm_timer_pdev->dev))
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+ omap->pdata->stop(omap->dm_timer);
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+
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+ omap->pdata->free(omap->dm_timer);
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+
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+ mutex_destroy(&omap->mutex);
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+
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+ return pwmchip_remove(&omap->chip);
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+}
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+
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+static const struct of_device_id pwm_omap_dmtimer_of_match[] = {
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+ {.compatible = "ti,omap-dmtimer-pwm"},
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+ {}
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+};
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+MODULE_DEVICE_TABLE(of, pwm_omap_dmtimer_of_match);
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+
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+static struct platform_driver pwm_omap_dmtimer_driver = {
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+ .driver = {
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+ .name = "omap-dmtimer-pwm",
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+ .of_match_table = of_match_ptr(pwm_omap_dmtimer_of_match),
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+ },
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+ .probe = pwm_omap_dmtimer_probe,
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+ .remove = pwm_omap_dmtimer_remove,
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+};
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+module_platform_driver(pwm_omap_dmtimer_driver);
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+
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+MODULE_AUTHOR("Grant Erickson <marathon96@gmail.com>");
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+MODULE_AUTHOR("NeilBrown <neilb@suse.de>");
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+MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
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+MODULE_LICENSE("GPL v2");
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+MODULE_DESCRIPTION("OMAP PWM Driver using Dual-mode Timers");
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Linus Torvalds