/*
 * SPEAr Keyboard Driver
 * Based on omap-keypad driver
 *
 * Copyright (C) 2010 ST Microelectronics
 * Rajeev Kumar <rajeevkumar.linux@gmail.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/clk.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/input.h>
#include <linux/input/matrix_keypad.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/types.h>

/* Keyboard Registers */
#define MODE_CTL_REG	0x00
#define STATUS_REG	0x0C
#define DATA_REG	0x10
#define INTR_MASK	0x54

/* Register Values */
#define NUM_ROWS	16
#define NUM_COLS	16
#define MODE_CTL_PCLK_FREQ_SHIFT	9
#define MODE_CTL_PCLK_FREQ_MSK		0x7F

#define MODE_CTL_KEYBOARD	(0x2 << 0)
#define MODE_CTL_SCAN_RATE_10	(0x0 << 2)
#define MODE_CTL_SCAN_RATE_20	(0x1 << 2)
#define MODE_CTL_SCAN_RATE_40	(0x2 << 2)
#define MODE_CTL_SCAN_RATE_80	(0x3 << 2)
#define MODE_CTL_KEYNUM_SHIFT	6
#define MODE_CTL_START_SCAN	(0x1 << 8)

#define STATUS_DATA_AVAIL	(0x1 << 1)

#define DATA_ROW_MASK		0xF0
#define DATA_COLUMN_MASK	0x0F

#define ROW_SHIFT		4

struct spear_kbd {
	struct input_dev *input;
	void __iomem *io_base;
	struct clk *clk;
	unsigned int irq;
	u32 mode;
	u32 suspended_rate;
	u32 mode_ctl_reg;
	unsigned short last_key;
	unsigned short keycodes[NUM_ROWS * NUM_COLS];
	bool irq_wake_enabled;
};

static irqreturn_t spear_kbd_interrupt(int irq, void *dev_id)
{
	struct spear_kbd *kbd = dev_id;
	struct input_dev *input = kbd->input;
	unsigned int key;
	u32 sts, val;

	sts = readl_relaxed(kbd->io_base + STATUS_REG);
	if (!(sts & STATUS_DATA_AVAIL))
		return IRQ_NONE;

	if (kbd->last_key != KEY_RESERVED) {
		input_report_key(input, kbd->last_key, 0);
		kbd->last_key = KEY_RESERVED;
	}

	/* following reads active (row, col) pair */
	val = readl_relaxed(kbd->io_base + DATA_REG) &
		(DATA_ROW_MASK | DATA_COLUMN_MASK);
	key = kbd->keycodes[val];

	input_event(input, EV_MSC, MSC_SCAN, val);
	input_report_key(input, key, 1);
	input_sync(input);

	kbd->last_key = key;

	/* clear interrupt */
	writel_relaxed(0, kbd->io_base + STATUS_REG);

	return IRQ_HANDLED;
}

static int spear_kbd_open(struct input_dev *dev)
{
	struct spear_kbd *kbd = input_get_drvdata(dev);
	int error;
	u32 val;

	kbd->last_key = KEY_RESERVED;

	error = clk_enable(kbd->clk);
	if (error)
		return error;

	/* keyboard rate to be programmed is input clock (in MHz) - 1 */
	val = clk_get_rate(kbd->clk) / 1000000 - 1;
	val = (val & MODE_CTL_PCLK_FREQ_MSK) << MODE_CTL_PCLK_FREQ_SHIFT;

	/* program keyboard */
	val = MODE_CTL_SCAN_RATE_80 | MODE_CTL_KEYBOARD | val |
		(kbd->mode << MODE_CTL_KEYNUM_SHIFT);
	writel_relaxed(val, kbd->io_base + MODE_CTL_REG);
	writel_relaxed(1, kbd->io_base + STATUS_REG);

	/* start key scan */
	val = readl_relaxed(kbd->io_base + MODE_CTL_REG);
	val |= MODE_CTL_START_SCAN;
	writel_relaxed(val, kbd->io_base + MODE_CTL_REG);

	return 0;
}

static void spear_kbd_close(struct input_dev *dev)
{
	struct spear_kbd *kbd = input_get_drvdata(dev);
	u32 val;

	/* stop key scan */
	val = readl_relaxed(kbd->io_base + MODE_CTL_REG);
	val &= ~MODE_CTL_START_SCAN;
	writel_relaxed(val, kbd->io_base + MODE_CTL_REG);

	clk_disable(kbd->clk);

	kbd->last_key = KEY_RESERVED;
}

static int spear_kbd_probe(struct platform_device *pdev)
{
	struct spear_kbd *kbd;
	struct input_dev *input_dev;
	int irq;
	int error;

	irq = platform_get_irq(pdev, 0);
	if (irq < 0)
		return irq;

	kbd = devm_kzalloc(&pdev->dev, sizeof(*kbd), GFP_KERNEL);
	if (!kbd) {
		dev_err(&pdev->dev, "not enough memory for driver data\n");
		return -ENOMEM;
	}

	error = device_property_read_u32(&pdev->dev, "st,mode", &kbd->mode);
	if (error) {
		dev_err(&pdev->dev, "Invalid or missing mode\n");
		return error;
	}

	device_property_read_u32(&pdev->dev, "suspended_rate", &kbd->suspended_rate);

	input_dev = devm_input_allocate_device(&pdev->dev);
	if (!input_dev) {
		dev_err(&pdev->dev, "unable to allocate input device\n");
		return -ENOMEM;
	}

	kbd->input = input_dev;
	kbd->irq = irq;

	kbd->io_base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
	if (IS_ERR(kbd->io_base))
		return PTR_ERR(kbd->io_base);

	kbd->clk = devm_clk_get_prepared(&pdev->dev, NULL);
	if (IS_ERR(kbd->clk))
		return PTR_ERR(kbd->clk);

	input_dev->name = "Spear Keyboard";
	input_dev->phys = "keyboard/input0";
	input_dev->id.bustype = BUS_HOST;
	input_dev->id.vendor = 0x0001;
	input_dev->id.product = 0x0001;
	input_dev->id.version = 0x0100;
	input_dev->open = spear_kbd_open;
	input_dev->close = spear_kbd_close;

	error = matrix_keypad_build_keymap(NULL, NULL, NUM_ROWS, NUM_COLS,
					   kbd->keycodes, input_dev);
	if (error) {
		dev_err(&pdev->dev, "Failed to build keymap\n");
		return error;
	}

	if (device_property_read_bool(&pdev->dev, "autorepeat"))
		__set_bit(EV_REP, input_dev->evbit);
	input_set_capability(input_dev, EV_MSC, MSC_SCAN);

	input_set_drvdata(input_dev, kbd);

	error = devm_request_irq(&pdev->dev, irq, spear_kbd_interrupt, 0,
				 "keyboard", kbd);
	if (error) {
		dev_err(&pdev->dev, "request_irq failed\n");
		return error;
	}

	error = input_register_device(input_dev);
	if (error) {
		dev_err(&pdev->dev, "Unable to register keyboard device\n");
		return error;
	}

	device_init_wakeup(&pdev->dev, 1);
	platform_set_drvdata(pdev, kbd);

	return 0;
}

static int spear_kbd_suspend(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct spear_kbd *kbd = platform_get_drvdata(pdev);
	struct input_dev *input_dev = kbd->input;
	unsigned int rate = 0, mode_ctl_reg, val;

	guard(mutex)(&input_dev->mutex);

	/* explicitly enable clock as we may program device */
	clk_enable(kbd->clk);

	mode_ctl_reg = readl_relaxed(kbd->io_base + MODE_CTL_REG);

	if (device_may_wakeup(&pdev->dev)) {
		if (!enable_irq_wake(kbd->irq))
			kbd->irq_wake_enabled = true;

		/*
		 * reprogram the keyboard operating frequency as on some
		 * platform it may change during system suspended
		 */
		if (kbd->suspended_rate)
			rate = kbd->suspended_rate / 1000000 - 1;
		else
			rate = clk_get_rate(kbd->clk) / 1000000 - 1;

		val = mode_ctl_reg &
			~(MODE_CTL_PCLK_FREQ_MSK << MODE_CTL_PCLK_FREQ_SHIFT);
		val |= (rate & MODE_CTL_PCLK_FREQ_MSK)
			<< MODE_CTL_PCLK_FREQ_SHIFT;
		writel_relaxed(val, kbd->io_base + MODE_CTL_REG);

	} else {
		if (input_device_enabled(input_dev)) {
			writel_relaxed(mode_ctl_reg & ~MODE_CTL_START_SCAN,
					kbd->io_base + MODE_CTL_REG);
			clk_disable(kbd->clk);
		}
	}

	/* store current configuration */
	if (input_device_enabled(input_dev))
		kbd->mode_ctl_reg = mode_ctl_reg;

	/* restore previous clk state */
	clk_disable(kbd->clk);

	return 0;
}

static int spear_kbd_resume(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct spear_kbd *kbd = platform_get_drvdata(pdev);
	struct input_dev *input_dev = kbd->input;

	guard(mutex)(&input_dev->mutex);

	if (device_may_wakeup(&pdev->dev)) {
		if (kbd->irq_wake_enabled) {
			kbd->irq_wake_enabled = false;
			disable_irq_wake(kbd->irq);
		}
	} else {
		if (input_device_enabled(input_dev))
			clk_enable(kbd->clk);
	}

	/* restore current configuration */
	if (input_device_enabled(input_dev))
		writel_relaxed(kbd->mode_ctl_reg, kbd->io_base + MODE_CTL_REG);

	return 0;
}

static DEFINE_SIMPLE_DEV_PM_OPS(spear_kbd_pm_ops,
				spear_kbd_suspend, spear_kbd_resume);

#ifdef CONFIG_OF
static const struct of_device_id spear_kbd_id_table[] = {
	{ .compatible = "st,spear300-kbd" },
	{}
};
MODULE_DEVICE_TABLE(of, spear_kbd_id_table);
#endif

static struct platform_driver spear_kbd_driver = {
	.probe		= spear_kbd_probe,
	.driver		= {
		.name	= "keyboard",
		.pm	= pm_sleep_ptr(&spear_kbd_pm_ops),
		.of_match_table = of_match_ptr(spear_kbd_id_table),
	},
};
module_platform_driver(spear_kbd_driver);

MODULE_AUTHOR("Rajeev Kumar");
MODULE_DESCRIPTION("SPEAr Keyboard Driver");
MODULE_LICENSE("GPL");