/*
 * TI AEMIF driver
 *
 * Copyright (C) 2010 - 2013 Texas Instruments Incorporated. http://www.ti.com/
 *
 * Authors:
 * Murali Karicheri <m-karicheri2@ti.com>
 * Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>
 *
 * 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.
 */

#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>

#define TA_SHIFT	2
#define RHOLD_SHIFT	4
#define RSTROBE_SHIFT	7
#define RSETUP_SHIFT	13
#define WHOLD_SHIFT	17
#define WSTROBE_SHIFT	20
#define WSETUP_SHIFT	26
#define EW_SHIFT	30
#define SS_SHIFT	31

#define TA(x)		((x) << TA_SHIFT)
#define RHOLD(x)	((x) << RHOLD_SHIFT)
#define RSTROBE(x)	((x) << RSTROBE_SHIFT)
#define RSETUP(x)	((x) << RSETUP_SHIFT)
#define WHOLD(x)	((x) << WHOLD_SHIFT)
#define WSTROBE(x)	((x) << WSTROBE_SHIFT)
#define WSETUP(x)	((x) << WSETUP_SHIFT)
#define EW(x)		((x) << EW_SHIFT)
#define SS(x)		((x) << SS_SHIFT)

#define ASIZE_MAX	0x1
#define TA_MAX		0x3
#define RHOLD_MAX	0x7
#define RSTROBE_MAX	0x3f
#define RSETUP_MAX	0xf
#define WHOLD_MAX	0x7
#define WSTROBE_MAX	0x3f
#define WSETUP_MAX	0xf
#define EW_MAX		0x1
#define SS_MAX		0x1
#define NUM_CS		4

#define TA_VAL(x)	(((x) & TA(TA_MAX)) >> TA_SHIFT)
#define RHOLD_VAL(x)	(((x) & RHOLD(RHOLD_MAX)) >> RHOLD_SHIFT)
#define RSTROBE_VAL(x)	(((x) & RSTROBE(RSTROBE_MAX)) >> RSTROBE_SHIFT)
#define RSETUP_VAL(x)	(((x) & RSETUP(RSETUP_MAX)) >> RSETUP_SHIFT)
#define WHOLD_VAL(x)	(((x) & WHOLD(WHOLD_MAX)) >> WHOLD_SHIFT)
#define WSTROBE_VAL(x)	(((x) & WSTROBE(WSTROBE_MAX)) >> WSTROBE_SHIFT)
#define WSETUP_VAL(x)	(((x) & WSETUP(WSETUP_MAX)) >> WSETUP_SHIFT)
#define EW_VAL(x)	(((x) & EW(EW_MAX)) >> EW_SHIFT)
#define SS_VAL(x)	(((x) & SS(SS_MAX)) >> SS_SHIFT)

#define NRCSR_OFFSET	0x00
#define AWCCR_OFFSET	0x04
#define A1CR_OFFSET	0x10

#define ACR_ASIZE_MASK	0x3
#define ACR_EW_MASK	BIT(30)
#define ACR_SS_MASK	BIT(31)
#define ASIZE_16BIT	1

#define CONFIG_MASK	(TA(TA_MAX) | \
				RHOLD(RHOLD_MAX) | \
				RSTROBE(RSTROBE_MAX) |	\
				RSETUP(RSETUP_MAX) | \
				WHOLD(WHOLD_MAX) | \
				WSTROBE(WSTROBE_MAX) | \
				WSETUP(WSETUP_MAX) | \
				EW(EW_MAX) | SS(SS_MAX) | \
				ASIZE_MAX)

/**
 * struct aemif_cs_data: structure to hold cs parameters
 * @cs: chip-select number
 * @wstrobe: write strobe width, ns
 * @rstrobe: read strobe width, ns
 * @wsetup: write setup width, ns
 * @whold: write hold width, ns
 * @rsetup: read setup width, ns
 * @rhold: read hold width, ns
 * @ta: minimum turn around time, ns
 * @enable_ss: enable/disable select strobe mode
 * @enable_ew: enable/disable extended wait mode
 * @asize: width of the asynchronous device's data bus
 */
struct aemif_cs_data {
	u8	cs;
	u16	wstrobe;
	u16	rstrobe;
	u8	wsetup;
	u8	whold;
	u8	rsetup;
	u8	rhold;
	u8	ta;
	u8	enable_ss;
	u8	enable_ew;
	u8	asize;
};

/**
 * struct aemif_device: structure to hold device data
 * @base: base address of AEMIF registers
 * @clk: source clock
 * @clk_rate: clock's rate in kHz
 * @num_cs: number of assigned chip-selects
 * @cs_offset: start number of cs nodes
 * @cs_data: array of chip-select settings
 */
struct aemif_device {
	void __iomem *base;
	struct clk *clk;
	unsigned long clk_rate;
	u8 num_cs;
	int cs_offset;
	struct aemif_cs_data cs_data[NUM_CS];
};

/**
 * aemif_calc_rate - calculate timing data.
 * @pdev: platform device to calculate for
 * @wanted: The cycle time needed in nanoseconds.
 * @clk: The input clock rate in kHz.
 * @max: The maximum divider value that can be programmed.
 *
 * On success, returns the calculated timing value minus 1 for easy
 * programming into AEMIF timing registers, else negative errno.
 */
static int aemif_calc_rate(struct platform_device *pdev, int wanted,
			   unsigned long clk, int max)
{
	int result;

	result = DIV_ROUND_UP((wanted * clk), NSEC_PER_MSEC) - 1;

	dev_dbg(&pdev->dev, "%s: result %d from %ld, %d\n", __func__, result,
		clk, wanted);

	/* It is generally OK to have a more relaxed timing than requested... */
	if (result < 0)
		result = 0;

	/* ... But configuring tighter timings is not an option. */
	else if (result > max)
		result = -EINVAL;

	return result;
}

/**
 * aemif_config_abus - configure async bus parameters
 * @pdev: platform device to configure for
 * @csnum: aemif chip select number
 *
 * This function programs the given timing values (in real clock) into the
 * AEMIF registers taking the AEMIF clock into account.
 *
 * This function does not use any locking while programming the AEMIF
 * because it is expected that there is only one user of a given
 * chip-select.
 *
 * Returns 0 on success, else negative errno.
 */
static int aemif_config_abus(struct platform_device *pdev, int csnum)
{
	struct aemif_device *aemif = platform_get_drvdata(pdev);
	struct aemif_cs_data *data = &aemif->cs_data[csnum];
	int ta, rhold, rstrobe, rsetup, whold, wstrobe, wsetup;
	unsigned long clk_rate = aemif->clk_rate;
	unsigned offset;
	u32 set, val;

	offset = A1CR_OFFSET + (data->cs - aemif->cs_offset) * 4;

	ta	= aemif_calc_rate(pdev, data->ta, clk_rate, TA_MAX);
	rhold	= aemif_calc_rate(pdev, data->rhold, clk_rate, RHOLD_MAX);
	rstrobe	= aemif_calc_rate(pdev, data->rstrobe, clk_rate, RSTROBE_MAX);
	rsetup	= aemif_calc_rate(pdev, data->rsetup, clk_rate, RSETUP_MAX);
	whold	= aemif_calc_rate(pdev, data->whold, clk_rate, WHOLD_MAX);
	wstrobe	= aemif_calc_rate(pdev, data->wstrobe, clk_rate, WSTROBE_MAX);
	wsetup	= aemif_calc_rate(pdev, data->wsetup, clk_rate, WSETUP_MAX);

	if (ta < 0 || rhold < 0 || rstrobe < 0 || rsetup < 0 ||
	    whold < 0 || wstrobe < 0 || wsetup < 0) {
		dev_err(&pdev->dev, "%s: cannot get suitable timings\n",
			__func__);
		return -EINVAL;
	}

	set = TA(ta) | RHOLD(rhold) | RSTROBE(rstrobe) | RSETUP(rsetup) |
		WHOLD(whold) | WSTROBE(wstrobe) | WSETUP(wsetup);

	set |= (data->asize & ACR_ASIZE_MASK);
	if (data->enable_ew)
		set |= ACR_EW_MASK;
	if (data->enable_ss)
		set |= ACR_SS_MASK;

	val = readl(aemif->base + offset);
	val &= ~CONFIG_MASK;
	val |= set;
	writel(val, aemif->base + offset);

	return 0;
}

static inline int aemif_cycles_to_nsec(int val, unsigned long clk_rate)
{
	return ((val + 1) * NSEC_PER_MSEC) / clk_rate;
}

/**
 * aemif_get_hw_params - function to read hw register values
 * @pdev: platform device to read for
 * @csnum: aemif chip select number
 *
 * This function reads the defaults from the registers and update
 * the timing values. Required for get/set commands and also for
 * the case when driver needs to use defaults in hardware.
 */
static void aemif_get_hw_params(struct platform_device *pdev, int csnum)
{
	struct aemif_device *aemif = platform_get_drvdata(pdev);
	struct aemif_cs_data *data = &aemif->cs_data[csnum];
	unsigned long clk_rate = aemif->clk_rate;
	u32 val, offset;

	offset = A1CR_OFFSET + (data->cs - aemif->cs_offset) * 4;
	val = readl(aemif->base + offset);

	data->ta = aemif_cycles_to_nsec(TA_VAL(val), clk_rate);
	data->rhold = aemif_cycles_to_nsec(RHOLD_VAL(val), clk_rate);
	data->rstrobe = aemif_cycles_to_nsec(RSTROBE_VAL(val), clk_rate);
	data->rsetup = aemif_cycles_to_nsec(RSETUP_VAL(val), clk_rate);
	data->whold = aemif_cycles_to_nsec(WHOLD_VAL(val), clk_rate);
	data->wstrobe = aemif_cycles_to_nsec(WSTROBE_VAL(val), clk_rate);
	data->wsetup = aemif_cycles_to_nsec(WSETUP_VAL(val), clk_rate);
	data->enable_ew = EW_VAL(val);
	data->enable_ss = SS_VAL(val);
	data->asize = val & ASIZE_MAX;
}

/**
 * of_aemif_parse_abus_config - parse CS configuration from DT
 * @pdev: platform device to parse for
 * @np: device node ptr
 *
 * This function update the emif async bus configuration based on the values
 * configured in a cs device binding node.
 */
static int of_aemif_parse_abus_config(struct platform_device *pdev,
				      struct device_node *np)
{
	struct aemif_device *aemif = platform_get_drvdata(pdev);
	struct aemif_cs_data *data;
	u32 cs;
	u32 val;

	if (of_property_read_u32(np, "ti,cs-chipselect", &cs)) {
		dev_dbg(&pdev->dev, "cs property is required");
		return -EINVAL;
	}

	if (cs - aemif->cs_offset >= NUM_CS || cs < aemif->cs_offset) {
		dev_dbg(&pdev->dev, "cs number is incorrect %d", cs);
		return -EINVAL;
	}

	if (aemif->num_cs >= NUM_CS) {
		dev_dbg(&pdev->dev, "cs count is more than %d", NUM_CS);
		return -EINVAL;
	}

	data = &aemif->cs_data[aemif->num_cs];
	data->cs = cs;

	/* read the current value in the hw register */
	aemif_get_hw_params(pdev, aemif->num_cs++);

	/* override the values from device node */
	if (!of_property_read_u32(np, "ti,cs-min-turnaround-ns", &val))
		data->ta = val;

	if (!of_property_read_u32(np, "ti,cs-read-hold-ns", &val))
		data->rhold = val;

	if (!of_property_read_u32(np, "ti,cs-read-strobe-ns", &val))
		data->rstrobe = val;

	if (!of_property_read_u32(np, "ti,cs-read-setup-ns", &val))
		data->rsetup = val;

	if (!of_property_read_u32(np, "ti,cs-write-hold-ns", &val))
		data->whold = val;

	if (!of_property_read_u32(np, "ti,cs-write-strobe-ns", &val))
		data->wstrobe = val;

	if (!of_property_read_u32(np, "ti,cs-write-setup-ns", &val))
		data->wsetup = val;

	if (!of_property_read_u32(np, "ti,cs-bus-width", &val))
		if (val == 16)
			data->asize = 1;
	data->enable_ew = of_property_read_bool(np, "ti,cs-extended-wait-mode");
	data->enable_ss = of_property_read_bool(np, "ti,cs-select-strobe-mode");
	return 0;
}

static const struct of_device_id aemif_of_match[] = {
	{ .compatible = "ti,davinci-aemif", },
	{ .compatible = "ti,da850-aemif", },
	{},
};

static int aemif_probe(struct platform_device *pdev)
{
	int i;
	int ret = -ENODEV;
	struct resource *res;
	struct device *dev = &pdev->dev;
	struct device_node *np = dev->of_node;
	struct device_node *child_np;
	struct aemif_device *aemif;

	if (np == NULL)
		return 0;

	aemif = devm_kzalloc(dev, sizeof(*aemif), GFP_KERNEL);
	if (!aemif)
		return -ENOMEM;

	platform_set_drvdata(pdev, aemif);

	aemif->clk = devm_clk_get(dev, NULL);
	if (IS_ERR(aemif->clk)) {
		dev_err(dev, "cannot get clock 'aemif'\n");
		return PTR_ERR(aemif->clk);
	}

	clk_prepare_enable(aemif->clk);
	aemif->clk_rate = clk_get_rate(aemif->clk) / MSEC_PER_SEC;

	if (of_device_is_compatible(np, "ti,da850-aemif"))
		aemif->cs_offset = 2;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	aemif->base = devm_ioremap_resource(dev, res);
	if (IS_ERR(aemif->base)) {
		ret = PTR_ERR(aemif->base);
		goto error;
	}

	/*
	 * For every controller device node, there is a cs device node that
	 * describe the bus configuration parameters. This functions iterate
	 * over these nodes and update the cs data array.
	 */
	for_each_available_child_of_node(np, child_np) {
		ret = of_aemif_parse_abus_config(pdev, child_np);
		if (ret < 0)
			goto error;
	}

	for (i = 0; i < aemif->num_cs; i++) {
		ret = aemif_config_abus(pdev, i);
		if (ret < 0) {
			dev_err(dev, "Error configuring chip select %d\n",
				aemif->cs_data[i].cs);
			goto error;
		}
	}

	/*
	 * Create a child devices explicitly from here to
	 * guarantee that the child will be probed after the AEMIF timing
	 * parameters are set.
	 */
	for_each_available_child_of_node(np, child_np) {
		ret = of_platform_populate(child_np, NULL, NULL, dev);
		if (ret < 0)
			goto error;
	}

	return 0;
error:
	clk_disable_unprepare(aemif->clk);
	return ret;
}

static int aemif_remove(struct platform_device *pdev)
{
	struct aemif_device *aemif = platform_get_drvdata(pdev);

	clk_disable_unprepare(aemif->clk);
	return 0;
}

static struct platform_driver aemif_driver = {
	.probe = aemif_probe,
	.remove = aemif_remove,
	.driver = {
		.name = KBUILD_MODNAME,
		.owner = THIS_MODULE,
		.of_match_table = of_match_ptr(aemif_of_match),
	},
};

module_platform_driver(aemif_driver);

MODULE_AUTHOR("Murali Karicheri <m-karicheri2@ti.com>");
MODULE_AUTHOR("Ivan Khoronzhuk <ivan.khoronzhuk@ti.com>");
MODULE_DESCRIPTION("Texas Instruments AEMIF driver");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" KBUILD_MODNAME);