// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * ECAP Capture driver
 *
 * Copyright (C) 2022 Julien Panis <jpanis@baylibre.com>
 */

#include <linux/atomic.h>
#include <linux/clk.h>
#include <linux/counter.h>
#include <linux/err.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/mutex.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/regmap.h>

#define ECAP_DRV_NAME "ecap"

/* ECAP event IDs */
#define ECAP_CEVT1		0
#define ECAP_CEVT2		1
#define ECAP_CEVT3		2
#define ECAP_CEVT4		3
#define ECAP_CNTOVF		4

#define ECAP_CEVT_LAST		ECAP_CEVT4
#define ECAP_NB_CEVT		(ECAP_CEVT_LAST + 1)

#define ECAP_EVT_LAST		ECAP_CNTOVF
#define ECAP_NB_EVT		(ECAP_EVT_LAST + 1)

/* Registers */
#define ECAP_TSCNT_REG			0x00

#define ECAP_CAP_REG(i)		(((i) << 2) + 0x08)

#define ECAP_ECCTL_REG			0x28
#define ECAP_CAPPOL_BIT(i)		BIT((i) << 1)
#define ECAP_EV_MODE_MASK		GENMASK(7, 0)
#define ECAP_CAPLDEN_BIT		BIT(8)
#define ECAP_CONT_ONESHT_BIT		BIT(16)
#define ECAP_STOPVALUE_MASK		GENMASK(18, 17)
#define ECAP_TSCNTSTP_BIT		BIT(20)
#define ECAP_SYNCO_DIS_MASK		GENMASK(23, 22)
#define ECAP_CAP_APWM_BIT		BIT(25)
#define ECAP_ECCTL_EN_MASK		(ECAP_CAPLDEN_BIT | ECAP_TSCNTSTP_BIT)
#define ECAP_ECCTL_CFG_MASK		(ECAP_SYNCO_DIS_MASK | ECAP_STOPVALUE_MASK	\
					| ECAP_ECCTL_EN_MASK | ECAP_CAP_APWM_BIT	\
					| ECAP_CONT_ONESHT_BIT)

#define ECAP_ECINT_EN_FLG_REG		0x2c
#define ECAP_EVT_EN_MASK		GENMASK(ECAP_NB_EVT, ECAP_NB_CEVT)
#define ECAP_EVT_FLG_BIT(i)		BIT((i) + 17)

#define ECAP_ECINT_CLR_FRC_REG	0x30
#define ECAP_INT_CLR_BIT		BIT(0)
#define ECAP_EVT_CLR_BIT(i)		BIT((i) + 1)
#define ECAP_EVT_CLR_MASK		GENMASK(ECAP_NB_EVT, 0)

#define ECAP_PID_REG			0x5c

/* ECAP signals */
#define ECAP_CLOCK_SIG 0
#define ECAP_INPUT_SIG 1

static const struct regmap_config ecap_cnt_regmap_config = {
	.reg_bits = 32,
	.reg_stride = 4,
	.val_bits = 32,
	.max_register = ECAP_PID_REG,
};

/**
 * struct ecap_cnt_dev - device private data structure
 * @enabled: device state
 * @lock:    synchronization lock to prevent I/O race conditions
 * @clk:     device clock
 * @regmap:  device register map
 * @nb_ovf:  number of overflows since capture start
 * @pm_ctx:  device context for PM operations
 * @pm_ctx.ev_mode:   event mode bits
 * @pm_ctx.time_cntr: timestamp counter value
 */
struct ecap_cnt_dev {
	bool enabled;
	struct mutex lock;
	struct clk *clk;
	struct regmap *regmap;
	atomic_t nb_ovf;
	struct {
		u8 ev_mode;
		u32 time_cntr;
	} pm_ctx;
};

static u8 ecap_cnt_capture_get_evmode(struct counter_device *counter)
{
	struct ecap_cnt_dev *ecap_dev = counter_priv(counter);
	unsigned int regval;

	pm_runtime_get_sync(counter->parent);
	regmap_read(ecap_dev->regmap, ECAP_ECCTL_REG, &regval);
	pm_runtime_put_sync(counter->parent);

	return regval;
}

static void ecap_cnt_capture_set_evmode(struct counter_device *counter, u8 ev_mode)
{
	struct ecap_cnt_dev *ecap_dev = counter_priv(counter);

	pm_runtime_get_sync(counter->parent);
	regmap_update_bits(ecap_dev->regmap, ECAP_ECCTL_REG, ECAP_EV_MODE_MASK, ev_mode);
	pm_runtime_put_sync(counter->parent);
}

static void ecap_cnt_capture_enable(struct counter_device *counter)
{
	struct ecap_cnt_dev *ecap_dev = counter_priv(counter);

	pm_runtime_get_sync(counter->parent);

	/* Enable interrupts on events */
	regmap_update_bits(ecap_dev->regmap, ECAP_ECINT_EN_FLG_REG,
			   ECAP_EVT_EN_MASK, ECAP_EVT_EN_MASK);

	/* Run counter */
	regmap_update_bits(ecap_dev->regmap, ECAP_ECCTL_REG, ECAP_ECCTL_CFG_MASK,
			   ECAP_SYNCO_DIS_MASK | ECAP_STOPVALUE_MASK | ECAP_ECCTL_EN_MASK);
}

static void ecap_cnt_capture_disable(struct counter_device *counter)
{
	struct ecap_cnt_dev *ecap_dev = counter_priv(counter);

	/* Stop counter */
	regmap_update_bits(ecap_dev->regmap, ECAP_ECCTL_REG, ECAP_ECCTL_EN_MASK, 0);

	/* Disable interrupts on events */
	regmap_update_bits(ecap_dev->regmap, ECAP_ECINT_EN_FLG_REG, ECAP_EVT_EN_MASK, 0);

	pm_runtime_put_sync(counter->parent);
}

static u32 ecap_cnt_count_get_val(struct counter_device *counter, unsigned int reg)
{
	struct ecap_cnt_dev *ecap_dev = counter_priv(counter);
	unsigned int regval;

	pm_runtime_get_sync(counter->parent);
	regmap_read(ecap_dev->regmap, reg, &regval);
	pm_runtime_put_sync(counter->parent);

	return regval;
}

static void ecap_cnt_count_set_val(struct counter_device *counter, unsigned int reg, u32 val)
{
	struct ecap_cnt_dev *ecap_dev = counter_priv(counter);

	pm_runtime_get_sync(counter->parent);
	regmap_write(ecap_dev->regmap, reg, val);
	pm_runtime_put_sync(counter->parent);
}

static int ecap_cnt_count_read(struct counter_device *counter,
			       struct counter_count *count, u64 *val)
{
	*val = ecap_cnt_count_get_val(counter, ECAP_TSCNT_REG);

	return 0;
}

static int ecap_cnt_count_write(struct counter_device *counter,
				struct counter_count *count, u64 val)
{
	if (val > U32_MAX)
		return -ERANGE;

	ecap_cnt_count_set_val(counter, ECAP_TSCNT_REG, val);

	return 0;
}

static int ecap_cnt_function_read(struct counter_device *counter,
				  struct counter_count *count,
				  enum counter_function *function)
{
	*function = COUNTER_FUNCTION_INCREASE;

	return 0;
}

static int ecap_cnt_action_read(struct counter_device *counter,
				struct counter_count *count,
				struct counter_synapse *synapse,
				enum counter_synapse_action *action)
{
	*action = (synapse->signal->id == ECAP_CLOCK_SIG) ?
		   COUNTER_SYNAPSE_ACTION_RISING_EDGE :
		   COUNTER_SYNAPSE_ACTION_NONE;

	return 0;
}

static int ecap_cnt_watch_validate(struct counter_device *counter,
				   const struct counter_watch *watch)
{
	if (watch->channel > ECAP_CEVT_LAST)
		return -EINVAL;

	switch (watch->event) {
	case COUNTER_EVENT_CAPTURE:
	case COUNTER_EVENT_OVERFLOW:
		return 0;
	default:
		return -EINVAL;
	}
}

static int ecap_cnt_clk_get_freq(struct counter_device *counter,
				 struct counter_signal *signal, u64 *freq)
{
	struct ecap_cnt_dev *ecap_dev = counter_priv(counter);

	*freq = clk_get_rate(ecap_dev->clk);

	return 0;
}

static int ecap_cnt_pol_read(struct counter_device *counter,
			     struct counter_signal *signal,
			     size_t idx, enum counter_signal_polarity *pol)
{
	struct ecap_cnt_dev *ecap_dev = counter_priv(counter);
	int bitval;

	pm_runtime_get_sync(counter->parent);
	bitval = regmap_test_bits(ecap_dev->regmap, ECAP_ECCTL_REG, ECAP_CAPPOL_BIT(idx));
	pm_runtime_put_sync(counter->parent);

	*pol = bitval ? COUNTER_SIGNAL_POLARITY_NEGATIVE : COUNTER_SIGNAL_POLARITY_POSITIVE;

	return 0;
}

static int ecap_cnt_pol_write(struct counter_device *counter,
			      struct counter_signal *signal,
			      size_t idx, enum counter_signal_polarity pol)
{
	struct ecap_cnt_dev *ecap_dev = counter_priv(counter);

	pm_runtime_get_sync(counter->parent);
	if (pol == COUNTER_SIGNAL_POLARITY_NEGATIVE)
		regmap_set_bits(ecap_dev->regmap, ECAP_ECCTL_REG, ECAP_CAPPOL_BIT(idx));
	else
		regmap_clear_bits(ecap_dev->regmap, ECAP_ECCTL_REG, ECAP_CAPPOL_BIT(idx));
	pm_runtime_put_sync(counter->parent);

	return 0;
}

static int ecap_cnt_cap_read(struct counter_device *counter,
			     struct counter_count *count,
			     size_t idx, u64 *cap)
{
	*cap = ecap_cnt_count_get_val(counter, ECAP_CAP_REG(idx));

	return 0;
}

static int ecap_cnt_cap_write(struct counter_device *counter,
			      struct counter_count *count,
			      size_t idx, u64 cap)
{
	if (cap > U32_MAX)
		return -ERANGE;

	ecap_cnt_count_set_val(counter, ECAP_CAP_REG(idx), cap);

	return 0;
}

static int ecap_cnt_nb_ovf_read(struct counter_device *counter,
				struct counter_count *count, u64 *val)
{
	struct ecap_cnt_dev *ecap_dev = counter_priv(counter);

	*val = atomic_read(&ecap_dev->nb_ovf);

	return 0;
}

static int ecap_cnt_nb_ovf_write(struct counter_device *counter,
				 struct counter_count *count, u64 val)
{
	struct ecap_cnt_dev *ecap_dev = counter_priv(counter);

	if (val > U32_MAX)
		return -ERANGE;

	atomic_set(&ecap_dev->nb_ovf, val);

	return 0;
}

static int ecap_cnt_ceiling_read(struct counter_device *counter,
				 struct counter_count *count, u64 *val)
{
	*val = U32_MAX;

	return 0;
}

static int ecap_cnt_enable_read(struct counter_device *counter,
				struct counter_count *count, u8 *enable)
{
	struct ecap_cnt_dev *ecap_dev = counter_priv(counter);

	*enable = ecap_dev->enabled;

	return 0;
}

static int ecap_cnt_enable_write(struct counter_device *counter,
				 struct counter_count *count, u8 enable)
{
	struct ecap_cnt_dev *ecap_dev = counter_priv(counter);

	mutex_lock(&ecap_dev->lock);

	if (enable == ecap_dev->enabled)
		goto out;

	if (enable)
		ecap_cnt_capture_enable(counter);
	else
		ecap_cnt_capture_disable(counter);
	ecap_dev->enabled = enable;

out:
	mutex_unlock(&ecap_dev->lock);

	return 0;
}

static const struct counter_ops ecap_cnt_ops = {
	.count_read = ecap_cnt_count_read,
	.count_write = ecap_cnt_count_write,
	.function_read = ecap_cnt_function_read,
	.action_read = ecap_cnt_action_read,
	.watch_validate = ecap_cnt_watch_validate,
};

static const enum counter_function ecap_cnt_functions[] = {
	COUNTER_FUNCTION_INCREASE,
};

static const enum counter_synapse_action ecap_cnt_clock_actions[] = {
	COUNTER_SYNAPSE_ACTION_RISING_EDGE,
};

static const enum counter_synapse_action ecap_cnt_input_actions[] = {
	COUNTER_SYNAPSE_ACTION_NONE,
};

static struct counter_comp ecap_cnt_clock_ext[] = {
	COUNTER_COMP_FREQUENCY(ecap_cnt_clk_get_freq),
};

static const enum counter_signal_polarity ecap_cnt_pol_avail[] = {
	COUNTER_SIGNAL_POLARITY_POSITIVE,
	COUNTER_SIGNAL_POLARITY_NEGATIVE,
};

static DEFINE_COUNTER_AVAILABLE(ecap_cnt_pol_available, ecap_cnt_pol_avail);
static DEFINE_COUNTER_ARRAY_POLARITY(ecap_cnt_pol_array, ecap_cnt_pol_available, ECAP_NB_CEVT);

static struct counter_comp ecap_cnt_signal_ext[] = {
	COUNTER_COMP_ARRAY_POLARITY(ecap_cnt_pol_read, ecap_cnt_pol_write, ecap_cnt_pol_array),
};

static struct counter_signal ecap_cnt_signals[] = {
	{
		.id = ECAP_CLOCK_SIG,
		.name = "Clock Signal",
		.ext = ecap_cnt_clock_ext,
		.num_ext = ARRAY_SIZE(ecap_cnt_clock_ext),
	},
	{
		.id = ECAP_INPUT_SIG,
		.name = "Input Signal",
		.ext = ecap_cnt_signal_ext,
		.num_ext = ARRAY_SIZE(ecap_cnt_signal_ext),
	},
};

static struct counter_synapse ecap_cnt_synapses[] = {
	{
		.actions_list = ecap_cnt_clock_actions,
		.num_actions = ARRAY_SIZE(ecap_cnt_clock_actions),
		.signal = &ecap_cnt_signals[ECAP_CLOCK_SIG],
	},
	{
		.actions_list = ecap_cnt_input_actions,
		.num_actions = ARRAY_SIZE(ecap_cnt_input_actions),
		.signal = &ecap_cnt_signals[ECAP_INPUT_SIG],
	},
};

static DEFINE_COUNTER_ARRAY_CAPTURE(ecap_cnt_cap_array, ECAP_NB_CEVT);

static struct counter_comp ecap_cnt_count_ext[] = {
	COUNTER_COMP_ARRAY_CAPTURE(ecap_cnt_cap_read, ecap_cnt_cap_write, ecap_cnt_cap_array),
	COUNTER_COMP_COUNT_U64("num_overflows", ecap_cnt_nb_ovf_read, ecap_cnt_nb_ovf_write),
	COUNTER_COMP_CEILING(ecap_cnt_ceiling_read, NULL),
	COUNTER_COMP_ENABLE(ecap_cnt_enable_read, ecap_cnt_enable_write),
};

static struct counter_count ecap_cnt_counts[] = {
	{
		.name = "Timestamp Counter",
		.functions_list = ecap_cnt_functions,
		.num_functions = ARRAY_SIZE(ecap_cnt_functions),
		.synapses = ecap_cnt_synapses,
		.num_synapses = ARRAY_SIZE(ecap_cnt_synapses),
		.ext = ecap_cnt_count_ext,
		.num_ext = ARRAY_SIZE(ecap_cnt_count_ext),
	},
};

static irqreturn_t ecap_cnt_isr(int irq, void *dev_id)
{
	struct counter_device *counter_dev = dev_id;
	struct ecap_cnt_dev *ecap_dev = counter_priv(counter_dev);
	unsigned int clr = 0;
	unsigned int flg;
	int i;

	regmap_read(ecap_dev->regmap, ECAP_ECINT_EN_FLG_REG, &flg);

	/* Check capture events */
	for (i = 0 ; i < ECAP_NB_CEVT ; i++) {
		if (flg & ECAP_EVT_FLG_BIT(i)) {
			counter_push_event(counter_dev, COUNTER_EVENT_CAPTURE, i);
			clr |= ECAP_EVT_CLR_BIT(i);
		}
	}

	/* Check counter overflow */
	if (flg & ECAP_EVT_FLG_BIT(ECAP_CNTOVF)) {
		atomic_inc(&ecap_dev->nb_ovf);
		for (i = 0 ; i < ECAP_NB_CEVT ; i++)
			counter_push_event(counter_dev, COUNTER_EVENT_OVERFLOW, i);
		clr |= ECAP_EVT_CLR_BIT(ECAP_CNTOVF);
	}

	clr |= ECAP_INT_CLR_BIT;
	regmap_update_bits(ecap_dev->regmap, ECAP_ECINT_CLR_FRC_REG, ECAP_EVT_CLR_MASK, clr);

	return IRQ_HANDLED;
}

static int ecap_cnt_probe(struct platform_device *pdev)
{
	struct device *dev = &pdev->dev;
	struct ecap_cnt_dev *ecap_dev;
	struct counter_device *counter_dev;
	void __iomem *mmio_base;
	unsigned long clk_rate;
	int ret;

	counter_dev = devm_counter_alloc(dev, sizeof(*ecap_dev));
	if (!counter_dev)
		return -ENOMEM;

	counter_dev->name = ECAP_DRV_NAME;
	counter_dev->parent = dev;
	counter_dev->ops = &ecap_cnt_ops;
	counter_dev->signals = ecap_cnt_signals;
	counter_dev->num_signals = ARRAY_SIZE(ecap_cnt_signals);
	counter_dev->counts = ecap_cnt_counts;
	counter_dev->num_counts = ARRAY_SIZE(ecap_cnt_counts);

	ecap_dev = counter_priv(counter_dev);

	mutex_init(&ecap_dev->lock);

	ecap_dev->clk = devm_clk_get_enabled(dev, "fck");
	if (IS_ERR(ecap_dev->clk))
		return dev_err_probe(dev, PTR_ERR(ecap_dev->clk), "failed to get clock\n");

	clk_rate = clk_get_rate(ecap_dev->clk);
	if (!clk_rate) {
		dev_err(dev, "failed to get clock rate\n");
		return -EINVAL;
	}

	mmio_base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(mmio_base))
		return PTR_ERR(mmio_base);

	ecap_dev->regmap = devm_regmap_init_mmio(dev, mmio_base, &ecap_cnt_regmap_config);
	if (IS_ERR(ecap_dev->regmap))
		return dev_err_probe(dev, PTR_ERR(ecap_dev->regmap), "failed to init regmap\n");

	ret = platform_get_irq(pdev, 0);
	if (ret < 0)
		return dev_err_probe(dev, ret, "failed to get irq\n");

	ret = devm_request_irq(dev, ret, ecap_cnt_isr, 0, pdev->name, counter_dev);
	if (ret)
		return dev_err_probe(dev, ret, "failed to request irq\n");

	platform_set_drvdata(pdev, counter_dev);

	ret = devm_pm_runtime_enable(dev);
	if (ret)
		return ret;

	ret = devm_counter_add(dev, counter_dev);
	if (ret)
		return dev_err_probe(dev, ret, "failed to add counter\n");

	return 0;
}

static void ecap_cnt_remove(struct platform_device *pdev)
{
	struct counter_device *counter_dev = platform_get_drvdata(pdev);
	struct ecap_cnt_dev *ecap_dev = counter_priv(counter_dev);

	if (ecap_dev->enabled)
		ecap_cnt_capture_disable(counter_dev);
}

static int ecap_cnt_suspend(struct device *dev)
{
	struct counter_device *counter_dev = dev_get_drvdata(dev);
	struct ecap_cnt_dev *ecap_dev = counter_priv(counter_dev);

	/* If eCAP is running, stop capture then save timestamp counter */
	if (ecap_dev->enabled) {
		/*
		 * Disabling capture has the following effects:
		 * - interrupts are disabled
		 * - loading of capture registers is disabled
		 * - timebase counter is stopped
		 */
		ecap_cnt_capture_disable(counter_dev);
		ecap_dev->pm_ctx.time_cntr = ecap_cnt_count_get_val(counter_dev, ECAP_TSCNT_REG);
	}

	ecap_dev->pm_ctx.ev_mode = ecap_cnt_capture_get_evmode(counter_dev);

	clk_disable(ecap_dev->clk);

	return 0;
}

static int ecap_cnt_resume(struct device *dev)
{
	struct counter_device *counter_dev = dev_get_drvdata(dev);
	struct ecap_cnt_dev *ecap_dev = counter_priv(counter_dev);
	int ret;

	ret = clk_enable(ecap_dev->clk);
	if (ret) {
		dev_err(dev, "Cannot enable clock %d\n", ret);
		return ret;
	}

	ecap_cnt_capture_set_evmode(counter_dev, ecap_dev->pm_ctx.ev_mode);

	/* If eCAP was running, restore timestamp counter then run capture */
	if (ecap_dev->enabled) {
		ecap_cnt_count_set_val(counter_dev, ECAP_TSCNT_REG, ecap_dev->pm_ctx.time_cntr);
		ecap_cnt_capture_enable(counter_dev);
	}

	return 0;
}

static DEFINE_SIMPLE_DEV_PM_OPS(ecap_cnt_pm_ops, ecap_cnt_suspend, ecap_cnt_resume);

static const struct of_device_id ecap_cnt_of_match[] = {
	{ .compatible	= "ti,am62-ecap-capture" },
	{},
};
MODULE_DEVICE_TABLE(of, ecap_cnt_of_match);

static struct platform_driver ecap_cnt_driver = {
	.probe = ecap_cnt_probe,
	.remove = ecap_cnt_remove,
	.driver = {
		.name = "ecap-capture",
		.of_match_table = ecap_cnt_of_match,
		.pm = pm_sleep_ptr(&ecap_cnt_pm_ops),
	},
};
module_platform_driver(ecap_cnt_driver);

MODULE_DESCRIPTION("ECAP Capture driver");
MODULE_AUTHOR("Julien Panis <jpanis@baylibre.com>");
MODULE_LICENSE("GPL");
MODULE_IMPORT_NS("COUNTER");