/*
 * Atmel AT91 and AVR32 continuous touch screen driver for Wolfson WM97xx AC97
 * codecs.
 *
 * Copyright (C) 2008 - 2009 Atmel Corporation
 *
 * 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/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/wm97xx.h>
#include <linux/timer.h>
#include <linux/gpio.h>
#include <linux/io.h>
#include <linux/slab.h>

#define AC97C_ICA		0x10
#define AC97C_CBRHR		0x30
#define AC97C_CBSR		0x38
#define AC97C_CBMR		0x3c
#define AC97C_IER		0x54
#define AC97C_IDR		0x58

#define AC97C_RXRDY		(1 << 4)
#define AC97C_OVRUN		(1 << 5)

#define AC97C_CMR_SIZE_20	(0 << 16)
#define AC97C_CMR_SIZE_18	(1 << 16)
#define AC97C_CMR_SIZE_16	(2 << 16)
#define AC97C_CMR_SIZE_10	(3 << 16)
#define AC97C_CMR_CEM_LITTLE	(1 << 18)
#define AC97C_CMR_CEM_BIG	(0 << 18)
#define AC97C_CMR_CENA		(1 << 21)

#define AC97C_INT_CBEVT		(1 << 4)

#define AC97C_SR_CAEVT		(1 << 3)

#define AC97C_CH_MASK(slot)						\
	(0x7 << (3 * (slot - 3)))
#define AC97C_CH_ASSIGN(slot, channel)					\
	(AC97C_CHANNEL_##channel << (3 * (slot - 3)))
#define AC97C_CHANNEL_NONE	0x0
#define AC97C_CHANNEL_B		0x2

#define ac97c_writel(chip, reg, val)			\
	__raw_writel((val), (chip)->regs + AC97C_##reg)
#define ac97c_readl(chip, reg)				\
	__raw_readl((chip)->regs + AC97C_##reg)

#ifdef CONFIG_CPU_AT32AP700X
#define ATMEL_WM97XX_AC97C_IOMEM	(0xfff02800)
#define ATMEL_WM97XX_AC97C_IRQ		(29)
#define ATMEL_WM97XX_GPIO_DEFAULT	(32+16) /* Pin 16 on port B. */
#else
#error Unknown CPU, this driver only supports AT32AP700X CPUs.
#endif

struct continuous {
	u16 id;    /* codec id */
	u8 code;   /* continuous code */
	u8 reads;  /* number of coord reads per read cycle */
	u32 speed; /* number of coords per second */
};

#define WM_READS(sp) ((sp / HZ) + 1)

static const struct continuous cinfo[] = {
	{WM9705_ID2, 0, WM_READS(94), 94},
	{WM9705_ID2, 1, WM_READS(188), 188},
	{WM9705_ID2, 2, WM_READS(375), 375},
	{WM9705_ID2, 3, WM_READS(750), 750},
	{WM9712_ID2, 0, WM_READS(94), 94},
	{WM9712_ID2, 1, WM_READS(188), 188},
	{WM9712_ID2, 2, WM_READS(375), 375},
	{WM9712_ID2, 3, WM_READS(750), 750},
	{WM9713_ID2, 0, WM_READS(94), 94},
	{WM9713_ID2, 1, WM_READS(120), 120},
	{WM9713_ID2, 2, WM_READS(154), 154},
	{WM9713_ID2, 3, WM_READS(188), 188},
};

/* Continuous speed index. */
static int sp_idx;

/*
 * Pen sampling frequency (Hz) in continuous mode.
 */
static int cont_rate = 188;
module_param(cont_rate, int, 0);
MODULE_PARM_DESC(cont_rate, "Sampling rate in continuous mode (Hz)");

/*
 * Pen down detection.
 *
 * This driver can either poll or use an interrupt to indicate a pen down
 * event. If the irq request fails then it will fall back to polling mode.
 */
static int pen_int = 1;
module_param(pen_int, int, 0);
MODULE_PARM_DESC(pen_int, "Pen down detection (1 = interrupt, 0 = polling)");

/*
 * Pressure readback.
 *
 * Set to 1 to read back pen down pressure.
 */
static int pressure;
module_param(pressure, int, 0);
MODULE_PARM_DESC(pressure, "Pressure readback (1 = pressure, 0 = no pressure)");

/*
 * AC97 touch data slot.
 *
 * Touch screen readback data ac97 slot.
 */
static int ac97_touch_slot = 5;
module_param(ac97_touch_slot, int, 0);
MODULE_PARM_DESC(ac97_touch_slot, "Touch screen data slot AC97 number");

/*
 * GPIO line number.
 *
 * Set to GPIO number where the signal from the WM97xx device is hooked up.
 */
static int atmel_gpio_line = ATMEL_WM97XX_GPIO_DEFAULT;
module_param(atmel_gpio_line, int, 0);
MODULE_PARM_DESC(atmel_gpio_line, "GPIO line number connected to WM97xx");

struct atmel_wm97xx {
	struct wm97xx		*wm;
	struct timer_list	pen_timer;
	void __iomem		*regs;
	unsigned long		ac97c_irq;
	unsigned long		gpio_pen;
	unsigned long		gpio_irq;
	unsigned short		x;
	unsigned short		y;
};

static irqreturn_t atmel_wm97xx_channel_b_interrupt(int irq, void *dev_id)
{
	struct atmel_wm97xx *atmel_wm97xx = dev_id;
	struct wm97xx *wm = atmel_wm97xx->wm;
	int status = ac97c_readl(atmel_wm97xx, CBSR);
	irqreturn_t retval = IRQ_NONE;

	if (status & AC97C_OVRUN) {
		dev_dbg(&wm->touch_dev->dev, "AC97C overrun\n");
		ac97c_readl(atmel_wm97xx, CBRHR);
		retval = IRQ_HANDLED;
	} else if (status & AC97C_RXRDY) {
		u16 data;
		u16 value;
		u16 source;
		u16 pen_down;

		data = ac97c_readl(atmel_wm97xx, CBRHR);
		value = data & 0x0fff;
		source = data & WM97XX_ADCSEL_MASK;
		pen_down = (data & WM97XX_PEN_DOWN) >> 8;

		if (source == WM97XX_ADCSEL_X)
			atmel_wm97xx->x = value;
		if (source == WM97XX_ADCSEL_Y)
			atmel_wm97xx->y = value;

		if (!pressure && source == WM97XX_ADCSEL_Y) {
			input_report_abs(wm->input_dev, ABS_X, atmel_wm97xx->x);
			input_report_abs(wm->input_dev, ABS_Y, atmel_wm97xx->y);
			input_report_key(wm->input_dev, BTN_TOUCH, pen_down);
			input_sync(wm->input_dev);
		} else if (pressure && source == WM97XX_ADCSEL_PRES) {
			input_report_abs(wm->input_dev, ABS_X, atmel_wm97xx->x);
			input_report_abs(wm->input_dev, ABS_Y, atmel_wm97xx->y);
			input_report_abs(wm->input_dev, ABS_PRESSURE, value);
			input_report_key(wm->input_dev, BTN_TOUCH, value);
			input_sync(wm->input_dev);
		}

		retval = IRQ_HANDLED;
	}

	return retval;
}

static void atmel_wm97xx_acc_pen_up(struct wm97xx *wm)
{
	struct atmel_wm97xx *atmel_wm97xx = platform_get_drvdata(wm->touch_dev);
	struct input_dev *input_dev = wm->input_dev;
	int pen_down = gpio_get_value(atmel_wm97xx->gpio_pen);

	if (pen_down != 0) {
		mod_timer(&atmel_wm97xx->pen_timer,
			  jiffies + msecs_to_jiffies(1));
	} else {
		if (pressure)
			input_report_abs(input_dev, ABS_PRESSURE, 0);
		input_report_key(input_dev, BTN_TOUCH, 0);
		input_sync(input_dev);
	}
}

static void atmel_wm97xx_pen_timer(unsigned long data)
{
	atmel_wm97xx_acc_pen_up((struct wm97xx *)data);
}

static int atmel_wm97xx_acc_startup(struct wm97xx *wm)
{
	struct atmel_wm97xx *atmel_wm97xx = platform_get_drvdata(wm->touch_dev);
	int idx = 0;

	if (wm->ac97 == NULL)
		return -ENODEV;

	for (idx = 0; idx < ARRAY_SIZE(cinfo); idx++) {
		if (wm->id != cinfo[idx].id)
			continue;

		sp_idx = idx;

		if (cont_rate <= cinfo[idx].speed)
			break;
	}

	wm->acc_rate = cinfo[sp_idx].code;
	wm->acc_slot = ac97_touch_slot;
	dev_info(&wm->touch_dev->dev, "atmel accelerated touchscreen driver, "
			"%d samples/sec\n", cinfo[sp_idx].speed);

	if (pen_int) {
		unsigned long reg;

		wm->pen_irq = atmel_wm97xx->gpio_irq;

		switch (wm->id) {
		case WM9712_ID2: /* Fall through. */
		case WM9713_ID2:
			/*
			 * Use GPIO 13 (PEN_DOWN) to assert GPIO line 3
			 * (PENDOWN).
			 */
			wm97xx_config_gpio(wm, WM97XX_GPIO_13, WM97XX_GPIO_IN,
					WM97XX_GPIO_POL_HIGH,
					WM97XX_GPIO_STICKY,
					WM97XX_GPIO_WAKE);
			wm97xx_config_gpio(wm, WM97XX_GPIO_3, WM97XX_GPIO_OUT,
					WM97XX_GPIO_POL_HIGH,
					WM97XX_GPIO_NOTSTICKY,
					WM97XX_GPIO_NOWAKE);
		case WM9705_ID2: /* Fall through. */
			/*
			 * Enable touch data slot in AC97 controller channel B.
			 */
			reg = ac97c_readl(atmel_wm97xx, ICA);
			reg &= ~AC97C_CH_MASK(wm->acc_slot);
			reg |= AC97C_CH_ASSIGN(wm->acc_slot, B);
			ac97c_writel(atmel_wm97xx, ICA, reg);

			/*
			 * Enable channel and interrupt for RXRDY and OVERRUN.
			 */
			ac97c_writel(atmel_wm97xx, CBMR, AC97C_CMR_CENA
					| AC97C_CMR_CEM_BIG
					| AC97C_CMR_SIZE_16
					| AC97C_OVRUN
					| AC97C_RXRDY);
			/* Dummy read to empty RXRHR. */
			ac97c_readl(atmel_wm97xx, CBRHR);
			/*
			 * Enable interrupt for channel B in the AC97
			 * controller.
			 */
			ac97c_writel(atmel_wm97xx, IER, AC97C_INT_CBEVT);
			break;
		default:
			dev_err(&wm->touch_dev->dev, "pen down irq not "
					"supported on this device\n");
			pen_int = 0;
			break;
		}
	}

	return 0;
}

static void atmel_wm97xx_acc_shutdown(struct wm97xx *wm)
{
	if (pen_int) {
		struct atmel_wm97xx *atmel_wm97xx =
			platform_get_drvdata(wm->touch_dev);
		unsigned long ica;

		switch (wm->id & 0xffff) {
		case WM9705_ID2: /* Fall through. */
		case WM9712_ID2: /* Fall through. */
		case WM9713_ID2:
			/* Disable slot and turn off channel B interrupts. */
			ica = ac97c_readl(atmel_wm97xx, ICA);
			ica &= ~AC97C_CH_MASK(wm->acc_slot);
			ac97c_writel(atmel_wm97xx, ICA, ica);
			ac97c_writel(atmel_wm97xx, IDR, AC97C_INT_CBEVT);
			ac97c_writel(atmel_wm97xx, CBMR, 0);
			wm->pen_irq = 0;
			break;
		default:
			dev_err(&wm->touch_dev->dev, "unknown codec\n");
			break;
		}
	}
}

static void atmel_wm97xx_irq_enable(struct wm97xx *wm, int enable)
{
	/* Intentionally left empty. */
}

static struct wm97xx_mach_ops atmel_mach_ops = {
	.acc_enabled	= 1,
	.acc_pen_up	= atmel_wm97xx_acc_pen_up,
	.acc_startup	= atmel_wm97xx_acc_startup,
	.acc_shutdown	= atmel_wm97xx_acc_shutdown,
	.irq_enable	= atmel_wm97xx_irq_enable,
	.irq_gpio	= WM97XX_GPIO_3,
};

static int __init atmel_wm97xx_probe(struct platform_device *pdev)
{
	struct wm97xx *wm = platform_get_drvdata(pdev);
	struct atmel_wm97xx *atmel_wm97xx;
	int ret;

	atmel_wm97xx = kzalloc(sizeof(struct atmel_wm97xx), GFP_KERNEL);
	if (!atmel_wm97xx)
		return -ENOMEM;

	atmel_wm97xx->wm	= wm;
	atmel_wm97xx->regs	= (void *)ATMEL_WM97XX_AC97C_IOMEM;
	atmel_wm97xx->ac97c_irq	= ATMEL_WM97XX_AC97C_IRQ;
	atmel_wm97xx->gpio_pen	= atmel_gpio_line;
	atmel_wm97xx->gpio_irq	= gpio_to_irq(atmel_wm97xx->gpio_pen);

	setup_timer(&atmel_wm97xx->pen_timer, atmel_wm97xx_pen_timer,
			(unsigned long)wm);

	ret = request_irq(atmel_wm97xx->ac97c_irq,
			  atmel_wm97xx_channel_b_interrupt,
			  IRQF_SHARED, "atmel-wm97xx-ch-b", atmel_wm97xx);
	if (ret) {
		dev_dbg(&pdev->dev, "could not request ac97c irq\n");
		goto err;
	}

	platform_set_drvdata(pdev, atmel_wm97xx);

	ret = wm97xx_register_mach_ops(wm, &atmel_mach_ops);
	if (ret)
		goto err_irq;

	return ret;

err_irq:
	free_irq(atmel_wm97xx->ac97c_irq, atmel_wm97xx);
err:
	kfree(atmel_wm97xx);
	return ret;
}

static int __exit atmel_wm97xx_remove(struct platform_device *pdev)
{
	struct atmel_wm97xx *atmel_wm97xx = platform_get_drvdata(pdev);
	struct wm97xx *wm = atmel_wm97xx->wm;

	ac97c_writel(atmel_wm97xx, IDR, AC97C_INT_CBEVT);
	free_irq(atmel_wm97xx->ac97c_irq, atmel_wm97xx);
	del_timer_sync(&atmel_wm97xx->pen_timer);
	wm97xx_unregister_mach_ops(wm);
	kfree(atmel_wm97xx);

	return 0;
}

#ifdef CONFIG_PM_SLEEP
static int atmel_wm97xx_suspend(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct atmel_wm97xx *atmel_wm97xx = platform_get_drvdata(pdev);

	ac97c_writel(atmel_wm97xx, IDR, AC97C_INT_CBEVT);
	disable_irq(atmel_wm97xx->gpio_irq);
	del_timer_sync(&atmel_wm97xx->pen_timer);

	return 0;
}

static int atmel_wm97xx_resume(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct atmel_wm97xx *atmel_wm97xx = platform_get_drvdata(pdev);
	struct wm97xx *wm = atmel_wm97xx->wm;

	if (wm->input_dev->users) {
		enable_irq(atmel_wm97xx->gpio_irq);
		ac97c_writel(atmel_wm97xx, IER, AC97C_INT_CBEVT);
	}

	return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(atmel_wm97xx_pm_ops,
			 atmel_wm97xx_suspend, atmel_wm97xx_resume);

static struct platform_driver atmel_wm97xx_driver = {
	.remove		= __exit_p(atmel_wm97xx_remove),
	.driver		= {
		.name	= "wm97xx-touch",
		.pm	= &atmel_wm97xx_pm_ops,
	},
};

module_platform_driver_probe(atmel_wm97xx_driver, atmel_wm97xx_probe);

MODULE_AUTHOR("Hans-Christian Egtvedt <egtvedt@samfundet.no>");
MODULE_DESCRIPTION("wm97xx continuous touch driver for Atmel AT91 and AVR32");
MODULE_LICENSE("GPL");