ARK-OS/arkos/kernel/drivers/input/keyboard/tegra-kbc.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Keyboard class input driver for the NVIDIA Tegra SoC internal matrix
 * keyboard controller
 *
 * Copyright (c) 2009-2011, NVIDIA Corporation.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/input.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/interrupt.h>
#include <linux/of.h>
#include <linux/property.h>
#include <linux/clk.h>
#include <linux/slab.h>
#include <linux/input/matrix_keypad.h>
#include <linux/reset.h>
#include <linux/err.h>

#define KBC_MAX_KPENT	8

/* Maximum row/column supported by Tegra KBC yet  is 16x8 */
#define KBC_MAX_GPIO	24
/* Maximum keys supported by Tegra KBC yet is 16 x 8*/
#define KBC_MAX_KEY	(16 * 8)

#define KBC_MAX_DEBOUNCE_CNT	0x3ffu

/* KBC row scan time and delay for beginning the row scan. */
#define KBC_ROW_SCAN_TIME	16
#define KBC_ROW_SCAN_DLY	5

/* KBC uses a 32KHz clock so a cycle = 1/32Khz */
#define KBC_CYCLE_MS	32

/* KBC Registers */

/* KBC Control Register */
#define KBC_CONTROL_0	0x0
#define KBC_FIFO_TH_CNT_SHIFT(cnt)	(cnt << 14)
#define KBC_DEBOUNCE_CNT_SHIFT(cnt)	(cnt << 4)
#define KBC_CONTROL_FIFO_CNT_INT_EN	(1 << 3)
#define KBC_CONTROL_KEYPRESS_INT_EN	(1 << 1)
#define KBC_CONTROL_KBC_EN		(1 << 0)

/* KBC Interrupt Register */
#define KBC_INT_0	0x4
#define KBC_INT_FIFO_CNT_INT_STATUS	(1 << 2)
#define KBC_INT_KEYPRESS_INT_STATUS	(1 << 0)

#define KBC_ROW_CFG0_0	0x8
#define KBC_COL_CFG0_0	0x18
#define KBC_TO_CNT_0	0x24
#define KBC_INIT_DLY_0	0x28
#define KBC_RPT_DLY_0	0x2c
#define KBC_KP_ENT0_0	0x30
#define KBC_KP_ENT1_0	0x34
#define KBC_ROW0_MASK_0	0x38

#define KBC_ROW_SHIFT	3

enum tegra_pin_type {
	PIN_CFG_IGNORE,
	PIN_CFG_COL,
	PIN_CFG_ROW,
};

/* Tegra KBC hw support */
struct tegra_kbc_hw_support {
	int max_rows;
	int max_columns;
};

struct tegra_kbc_pin_cfg {
	enum tegra_pin_type type;
	unsigned char num;
};

struct tegra_kbc {
	struct device *dev;
	unsigned int debounce_cnt;
	unsigned int repeat_cnt;
	struct tegra_kbc_pin_cfg pin_cfg[KBC_MAX_GPIO];
	const struct matrix_keymap_data *keymap_data;
	bool wakeup;
	void __iomem *mmio;
	struct input_dev *idev;
	int irq;
	spinlock_t lock;
	unsigned int repoll_dly;
	unsigned long cp_dly_jiffies;
	unsigned int cp_to_wkup_dly;
	bool use_fn_map;
	bool use_ghost_filter;
	bool keypress_caused_wake;
	unsigned short keycode[KBC_MAX_KEY * 2];
	unsigned short current_keys[KBC_MAX_KPENT];
	unsigned int num_pressed_keys;
	u32 wakeup_key;
	struct timer_list timer;
	struct clk *clk;
	struct reset_control *rst;
	const struct tegra_kbc_hw_support *hw_support;
	int max_keys;
	int num_rows_and_columns;
};

static void tegra_kbc_report_released_keys(struct input_dev *input,
					   unsigned short old_keycodes[],
					   unsigned int old_num_keys,
					   unsigned short new_keycodes[],
					   unsigned int new_num_keys)
{
	unsigned int i, j;

	for (i = 0; i < old_num_keys; i++) {
		for (j = 0; j < new_num_keys; j++)
			if (old_keycodes[i] == new_keycodes[j])
				break;

		if (j == new_num_keys)
			input_report_key(input, old_keycodes[i], 0);
	}
}

static void tegra_kbc_report_pressed_keys(struct input_dev *input,
					  unsigned char scancodes[],
					  unsigned short keycodes[],
					  unsigned int num_pressed_keys)
{
	unsigned int i;

	for (i = 0; i < num_pressed_keys; i++) {
		input_event(input, EV_MSC, MSC_SCAN, scancodes[i]);
		input_report_key(input, keycodes[i], 1);
	}
}

static void tegra_kbc_report_keys(struct tegra_kbc *kbc)
{
	unsigned char scancodes[KBC_MAX_KPENT];
	unsigned short keycodes[KBC_MAX_KPENT];
	u32 val = 0;
	unsigned int i;
	unsigned int num_down = 0;
	bool fn_keypress = false;
	bool key_in_same_row = false;
	bool key_in_same_col = false;

	for (i = 0; i < KBC_MAX_KPENT; i++) {
		if ((i % 4) == 0)
			val = readl(kbc->mmio + KBC_KP_ENT0_0 + i);

		if (val & 0x80) {
			unsigned int col = val & 0x07;
			unsigned int row = (val >> 3) & 0x0f;
			unsigned char scancode =
				MATRIX_SCAN_CODE(row, col, KBC_ROW_SHIFT);

			scancodes[num_down] = scancode;
			keycodes[num_down] = kbc->keycode[scancode];
			/* If driver uses Fn map, do not report the Fn key. */
			if ((keycodes[num_down] == KEY_FN) && kbc->use_fn_map)
				fn_keypress = true;
			else
				num_down++;
		}

		val >>= 8;
	}

	/*
	 * Matrix keyboard designs are prone to keyboard ghosting.
	 * Ghosting occurs if there are 3 keys such that -
	 * any 2 of the 3 keys share a row, and any 2 of them share a column.
	 * If so ignore the key presses for this iteration.
	 */
	if (kbc->use_ghost_filter && num_down >= 3) {
		for (i = 0; i < num_down; i++) {
			unsigned int j;
			u8 curr_col = scancodes[i] & 0x07;
			u8 curr_row = scancodes[i] >> KBC_ROW_SHIFT;

			/*
			 * Find 2 keys such that one key is in the same row
			 * and the other is in the same column as the i-th key.
			 */
			for (j = i + 1; j < num_down; j++) {
				u8 col = scancodes[j] & 0x07;
				u8 row = scancodes[j] >> KBC_ROW_SHIFT;

				if (col == curr_col)
					key_in_same_col = true;
				if (row == curr_row)
					key_in_same_row = true;
			}
		}
	}

	/*
	 * If the platform uses Fn keymaps, translate keys on a Fn keypress.
	 * Function keycodes are max_keys apart from the plain keycodes.
	 */
	if (fn_keypress) {
		for (i = 0; i < num_down; i++) {
			scancodes[i] += kbc->max_keys;
			keycodes[i] = kbc->keycode[scancodes[i]];
		}
	}

	/* Ignore the key presses for this iteration? */
	if (key_in_same_col && key_in_same_row)
		return;

	tegra_kbc_report_released_keys(kbc->idev,
				       kbc->current_keys, kbc->num_pressed_keys,
				       keycodes, num_down);
	tegra_kbc_report_pressed_keys(kbc->idev, scancodes, keycodes, num_down);
	input_sync(kbc->idev);

	memcpy(kbc->current_keys, keycodes, sizeof(kbc->current_keys));
	kbc->num_pressed_keys = num_down;
}

static void tegra_kbc_set_fifo_interrupt(struct tegra_kbc *kbc, bool enable)
{
	u32 val;

	val = readl(kbc->mmio + KBC_CONTROL_0);
	if (enable)
		val |= KBC_CONTROL_FIFO_CNT_INT_EN;
	else
		val &= ~KBC_CONTROL_FIFO_CNT_INT_EN;
	writel(val, kbc->mmio + KBC_CONTROL_0);
}

static void tegra_kbc_keypress_timer(struct timer_list *t)
{
	struct tegra_kbc *kbc = timer_container_of(kbc, t, timer);
	u32 val;
	unsigned int i;

	guard(spinlock_irqsave)(&kbc->lock);

	val = (readl(kbc->mmio + KBC_INT_0) >> 4) & 0xf;
	if (val) {
		unsigned long dly;

		tegra_kbc_report_keys(kbc);

		/*
		 * If more than one keys are pressed we need not wait
		 * for the repoll delay.
		 */
		dly = (val == 1) ? kbc->repoll_dly : 1;
		mod_timer(&kbc->timer, jiffies + msecs_to_jiffies(dly));
	} else {
		/* Release any pressed keys and exit the polling loop */
		for (i = 0; i < kbc->num_pressed_keys; i++)
			input_report_key(kbc->idev, kbc->current_keys[i], 0);
		input_sync(kbc->idev);

		kbc->num_pressed_keys = 0;

		/* All keys are released so enable the keypress interrupt */
		tegra_kbc_set_fifo_interrupt(kbc, true);
	}
}

static irqreturn_t tegra_kbc_isr(int irq, void *args)
{
	struct tegra_kbc *kbc = args;
	u32 val;

	guard(spinlock_irqsave)(&kbc->lock);

	/*
	 * Quickly bail out & reenable interrupts if the fifo threshold
	 * count interrupt wasn't the interrupt source
	 */
	val = readl(kbc->mmio + KBC_INT_0);
	writel(val, kbc->mmio + KBC_INT_0);

	if (val & KBC_INT_FIFO_CNT_INT_STATUS) {
		/*
		 * Until all keys are released, defer further processing to
		 * the polling loop in tegra_kbc_keypress_timer.
		 */
		tegra_kbc_set_fifo_interrupt(kbc, false);
		mod_timer(&kbc->timer, jiffies + kbc->cp_dly_jiffies);
	} else if (val & KBC_INT_KEYPRESS_INT_STATUS) {
		/* We can be here only through system resume path */
		kbc->keypress_caused_wake = true;
	}

	return IRQ_HANDLED;
}

static void tegra_kbc_setup_wakekeys(struct tegra_kbc *kbc, bool filter)
{
	int i;
	unsigned int rst_val;

	/* Either mask all keys or none. */
	rst_val = (filter && !kbc->wakeup) ? ~0 : 0;

	for (i = 0; i < kbc->hw_support->max_rows; i++)
		writel(rst_val, kbc->mmio + KBC_ROW0_MASK_0 + i * 4);
}

static void tegra_kbc_config_pins(struct tegra_kbc *kbc)
{
	int i;

	for (i = 0; i < KBC_MAX_GPIO; i++) {
		u32 r_shft = 5 * (i % 6);
		u32 c_shft = 4 * (i % 8);
		u32 r_mask = 0x1f << r_shft;
		u32 c_mask = 0x0f << c_shft;
		u32 r_offs = (i / 6) * 4 + KBC_ROW_CFG0_0;
		u32 c_offs = (i / 8) * 4 + KBC_COL_CFG0_0;
		u32 row_cfg = readl(kbc->mmio + r_offs);
		u32 col_cfg = readl(kbc->mmio + c_offs);

		row_cfg &= ~r_mask;
		col_cfg &= ~c_mask;

		switch (kbc->pin_cfg[i].type) {
		case PIN_CFG_ROW:
			row_cfg |= ((kbc->pin_cfg[i].num << 1) | 1) << r_shft;
			break;

		case PIN_CFG_COL:
			col_cfg |= ((kbc->pin_cfg[i].num << 1) | 1) << c_shft;
			break;

		case PIN_CFG_IGNORE:
			break;
		}

		writel(row_cfg, kbc->mmio + r_offs);
		writel(col_cfg, kbc->mmio + c_offs);
	}
}

static int tegra_kbc_start(struct tegra_kbc *kbc)
{
	unsigned int debounce_cnt;
	u32 val = 0;
	int ret;

	ret = clk_prepare_enable(kbc->clk);
	if (ret)
		return ret;

	/* Reset the KBC controller to clear all previous status.*/
	reset_control_assert(kbc->rst);
	udelay(100);
	reset_control_deassert(kbc->rst);
	udelay(100);

	tegra_kbc_config_pins(kbc);
	tegra_kbc_setup_wakekeys(kbc, false);

	writel(kbc->repeat_cnt, kbc->mmio + KBC_RPT_DLY_0);

	/* Keyboard debounce count is maximum of 12 bits. */
	debounce_cnt = min(kbc->debounce_cnt, KBC_MAX_DEBOUNCE_CNT);
	val = KBC_DEBOUNCE_CNT_SHIFT(debounce_cnt);
	val |= KBC_FIFO_TH_CNT_SHIFT(1); /* set fifo interrupt threshold to 1 */
	val |= KBC_CONTROL_FIFO_CNT_INT_EN;  /* interrupt on FIFO threshold */
	val |= KBC_CONTROL_KBC_EN;     /* enable */
	writel(val, kbc->mmio + KBC_CONTROL_0);

	/*
	 * Compute the delay(ns) from interrupt mode to continuous polling
	 * mode so the timer routine is scheduled appropriately.
	 */
	val = readl(kbc->mmio + KBC_INIT_DLY_0);
	kbc->cp_dly_jiffies = usecs_to_jiffies((val & 0xfffff) * 32);

	kbc->num_pressed_keys = 0;

	/*
	 * Atomically clear out any remaining entries in the key FIFO
	 * and enable keyboard interrupts.
	 */
	while (1) {
		val = readl(kbc->mmio + KBC_INT_0);
		val >>= 4;
		if (!val)
			break;

		val = readl(kbc->mmio + KBC_KP_ENT0_0);
		val = readl(kbc->mmio + KBC_KP_ENT1_0);
	}
	writel(0x7, kbc->mmio + KBC_INT_0);

	enable_irq(kbc->irq);

	return 0;
}

static void tegra_kbc_stop(struct tegra_kbc *kbc)
{
	u32 val;

	scoped_guard(spinlock_irqsave, &kbc->lock) {
		val = readl(kbc->mmio + KBC_CONTROL_0);
		val &= ~1;
		writel(val, kbc->mmio + KBC_CONTROL_0);
	}

	disable_irq(kbc->irq);
	timer_delete_sync(&kbc->timer);

	clk_disable_unprepare(kbc->clk);
}

static int tegra_kbc_open(struct input_dev *dev)
{
	struct tegra_kbc *kbc = input_get_drvdata(dev);

	return tegra_kbc_start(kbc);
}

static void tegra_kbc_close(struct input_dev *dev)
{
	struct tegra_kbc *kbc = input_get_drvdata(dev);

	return tegra_kbc_stop(kbc);
}

static bool tegra_kbc_check_pin_cfg(const struct tegra_kbc *kbc,
					unsigned int *num_rows)
{
	int i;

	*num_rows = 0;

	for (i = 0; i < KBC_MAX_GPIO; i++) {
		const struct tegra_kbc_pin_cfg *pin_cfg = &kbc->pin_cfg[i];

		switch (pin_cfg->type) {
		case PIN_CFG_ROW:
			if (pin_cfg->num >= kbc->hw_support->max_rows) {
				dev_err(kbc->dev,
					"pin_cfg[%d]: invalid row number %d\n",
					i, pin_cfg->num);
				return false;
			}
			(*num_rows)++;
			break;

		case PIN_CFG_COL:
			if (pin_cfg->num >= kbc->hw_support->max_columns) {
				dev_err(kbc->dev,
					"pin_cfg[%d]: invalid column number %d\n",
					i, pin_cfg->num);
				return false;
			}
			break;

		case PIN_CFG_IGNORE:
			break;

		default:
			dev_err(kbc->dev,
				"pin_cfg[%d]: invalid entry type %d\n",
				pin_cfg->type, pin_cfg->num);
			return false;
		}
	}

	return true;
}

static int tegra_kbc_parse_dt(struct tegra_kbc *kbc)
{
	struct device_node *np = kbc->dev->of_node;
	u32 prop;
	int i;
	int num_rows;
	int num_cols;
	u32 cols_cfg[KBC_MAX_GPIO];
	u32 rows_cfg[KBC_MAX_GPIO];

	if (!of_property_read_u32(np, "nvidia,debounce-delay-ms", &prop))
		kbc->debounce_cnt = prop;

	if (!of_property_read_u32(np, "nvidia,repeat-delay-ms", &prop))
		kbc->repeat_cnt = prop;

	kbc->use_ghost_filter = of_property_present(np, "nvidia,needs-ghost-filter");

	if (of_property_read_bool(np, "wakeup-source") ||
	    of_property_read_bool(np, "nvidia,wakeup-source")) /* legacy */
		kbc->wakeup = true;

	if (!of_property_present(np, "linux,keymap")) {
		dev_err(kbc->dev, "property linux,keymap not found\n");
		return -ENOENT;
	}

	/* Set all pins as non-configured */
	for (i = 0; i < kbc->num_rows_and_columns; i++)
		kbc->pin_cfg[i].type = PIN_CFG_IGNORE;

	num_rows = of_property_read_variable_u32_array(np, "nvidia,kbc-row-pins",
				rows_cfg, 1, KBC_MAX_GPIO);
	if (num_rows < 0) {
		dev_err(kbc->dev, "Rows configurations are not proper\n");
		return num_rows;
	} else if (num_rows > kbc->hw_support->max_rows) {
		dev_err(kbc->dev,
			"Number of rows is more than supported by hardware\n");
		return -EINVAL;
	}

	for (i = 0; i < num_rows; i++) {
		kbc->pin_cfg[rows_cfg[i]].type = PIN_CFG_ROW;
		kbc->pin_cfg[rows_cfg[i]].num = i;
	}

	num_cols = of_property_read_variable_u32_array(np, "nvidia,kbc-col-pins",
				cols_cfg, 1, KBC_MAX_GPIO);
	if (num_cols < 0) {
		dev_err(kbc->dev, "Cols configurations are not proper\n");
		return num_cols;
	} else if (num_cols > kbc->hw_support->max_columns) {
		dev_err(kbc->dev,
			"Number of cols is more than supported by hardware\n");
		return -EINVAL;
	}

	for (i = 0; i < num_cols; i++) {
		kbc->pin_cfg[cols_cfg[i]].type = PIN_CFG_COL;
		kbc->pin_cfg[cols_cfg[i]].num = i;
	}

	if (!num_rows || !num_cols || ((num_rows + num_cols) > KBC_MAX_GPIO)) {
		dev_err(kbc->dev,
			"keypad rows/columns not properly specified\n");
		return -EINVAL;
	}

	return 0;
}

static const struct tegra_kbc_hw_support tegra20_kbc_hw_support = {
	.max_rows	= 16,
	.max_columns	= 8,
};

static const struct tegra_kbc_hw_support tegra11_kbc_hw_support = {
	.max_rows	= 11,
	.max_columns	= 8,
};

static const struct of_device_id tegra_kbc_of_match[] = {
	{ .compatible = "nvidia,tegra114-kbc", .data = &tegra11_kbc_hw_support},
	{ .compatible = "nvidia,tegra30-kbc", .data = &tegra20_kbc_hw_support},
	{ .compatible = "nvidia,tegra20-kbc", .data = &tegra20_kbc_hw_support},
	{ },
};
MODULE_DEVICE_TABLE(of, tegra_kbc_of_match);

static int tegra_kbc_probe(struct platform_device *pdev)
{
	struct tegra_kbc *kbc;
	int err;
	int num_rows = 0;
	unsigned int debounce_cnt;
	unsigned int scan_time_rows;
	unsigned int keymap_rows;

	kbc = devm_kzalloc(&pdev->dev, sizeof(*kbc), GFP_KERNEL);
	if (!kbc) {
		dev_err(&pdev->dev, "failed to alloc memory for kbc\n");
		return -ENOMEM;
	}

	kbc->dev = &pdev->dev;
	kbc->hw_support = device_get_match_data(&pdev->dev);
	kbc->max_keys = kbc->hw_support->max_rows *
				kbc->hw_support->max_columns;
	kbc->num_rows_and_columns = kbc->hw_support->max_rows +
					kbc->hw_support->max_columns;
	keymap_rows = kbc->max_keys;
	spin_lock_init(&kbc->lock);

	err = tegra_kbc_parse_dt(kbc);
	if (err)
		return err;

	if (!tegra_kbc_check_pin_cfg(kbc, &num_rows))
		return -EINVAL;

	kbc->irq = platform_get_irq(pdev, 0);
	if (kbc->irq < 0)
		return -ENXIO;

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

	timer_setup(&kbc->timer, tegra_kbc_keypress_timer, 0);

	kbc->mmio = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(kbc->mmio))
		return PTR_ERR(kbc->mmio);

	kbc->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(kbc->clk)) {
		dev_err(&pdev->dev, "failed to get keyboard clock\n");
		return PTR_ERR(kbc->clk);
	}

	kbc->rst = devm_reset_control_get(&pdev->dev, "kbc");
	if (IS_ERR(kbc->rst)) {
		dev_err(&pdev->dev, "failed to get keyboard reset\n");
		return PTR_ERR(kbc->rst);
	}

	/*
	 * The time delay between two consecutive reads of the FIFO is
	 * the sum of the repeat time and the time taken for scanning
	 * the rows. There is an additional delay before the row scanning
	 * starts. The repoll delay is computed in milliseconds.
	 */
	debounce_cnt = min(kbc->debounce_cnt, KBC_MAX_DEBOUNCE_CNT);
	scan_time_rows = (KBC_ROW_SCAN_TIME + debounce_cnt) * num_rows;
	kbc->repoll_dly = KBC_ROW_SCAN_DLY + scan_time_rows + kbc->repeat_cnt;
	kbc->repoll_dly = DIV_ROUND_UP(kbc->repoll_dly, KBC_CYCLE_MS);

	kbc->idev->name = pdev->name;
	kbc->idev->id.bustype = BUS_HOST;
	kbc->idev->dev.parent = &pdev->dev;
	kbc->idev->open = tegra_kbc_open;
	kbc->idev->close = tegra_kbc_close;

	if (kbc->keymap_data && kbc->use_fn_map)
		keymap_rows *= 2;

	err = matrix_keypad_build_keymap(kbc->keymap_data, NULL,
					 keymap_rows,
					 kbc->hw_support->max_columns,
					 kbc->keycode, kbc->idev);
	if (err) {
		dev_err(&pdev->dev, "failed to setup keymap\n");
		return err;
	}

	__set_bit(EV_REP, kbc->idev->evbit);
	input_set_capability(kbc->idev, EV_MSC, MSC_SCAN);

	input_set_drvdata(kbc->idev, kbc);

	err = devm_request_irq(&pdev->dev, kbc->irq, tegra_kbc_isr,
			       IRQF_TRIGGER_HIGH | IRQF_NO_AUTOEN,
			       pdev->name, kbc);
	if (err) {
		dev_err(&pdev->dev, "failed to request keyboard IRQ\n");
		return err;
	}

	err = input_register_device(kbc->idev);
	if (err) {
		dev_err(&pdev->dev, "failed to register input device\n");
		return err;
	}

	platform_set_drvdata(pdev, kbc);
	device_init_wakeup(&pdev->dev, kbc->wakeup);

	return 0;
}

static void tegra_kbc_set_keypress_interrupt(struct tegra_kbc *kbc, bool enable)
{
	u32 val;

	val = readl(kbc->mmio + KBC_CONTROL_0);
	if (enable)
		val |= KBC_CONTROL_KEYPRESS_INT_EN;
	else
		val &= ~KBC_CONTROL_KEYPRESS_INT_EN;
	writel(val, kbc->mmio + KBC_CONTROL_0);
}

static int tegra_kbc_suspend(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct tegra_kbc *kbc = platform_get_drvdata(pdev);

	guard(mutex)(&kbc->idev->mutex);

	if (device_may_wakeup(&pdev->dev)) {
		disable_irq(kbc->irq);
		timer_delete_sync(&kbc->timer);
		tegra_kbc_set_fifo_interrupt(kbc, false);

		/* Forcefully clear the interrupt status */
		writel(0x7, kbc->mmio + KBC_INT_0);
		/*
		 * Store the previous resident time of continuous polling mode.
		 * Force the keyboard into interrupt mode.
		 */
		kbc->cp_to_wkup_dly = readl(kbc->mmio + KBC_TO_CNT_0);
		writel(0, kbc->mmio + KBC_TO_CNT_0);

		tegra_kbc_setup_wakekeys(kbc, true);
		msleep(30);

		kbc->keypress_caused_wake = false;
		/* Enable keypress interrupt before going into suspend. */
		tegra_kbc_set_keypress_interrupt(kbc, true);
		enable_irq(kbc->irq);
		enable_irq_wake(kbc->irq);
	} else if (input_device_enabled(kbc->idev)) {
		tegra_kbc_stop(kbc);
	}

	return 0;
}

static int tegra_kbc_resume(struct device *dev)
{
	struct platform_device *pdev = to_platform_device(dev);
	struct tegra_kbc *kbc = platform_get_drvdata(pdev);
	int err;

	guard(mutex)(&kbc->idev->mutex);

	if (device_may_wakeup(&pdev->dev)) {
		disable_irq_wake(kbc->irq);
		tegra_kbc_setup_wakekeys(kbc, false);
		/* We will use fifo interrupts for key detection. */
		tegra_kbc_set_keypress_interrupt(kbc, false);

		/* Restore the resident time of continuous polling mode. */
		writel(kbc->cp_to_wkup_dly, kbc->mmio + KBC_TO_CNT_0);

		tegra_kbc_set_fifo_interrupt(kbc, true);

		if (kbc->keypress_caused_wake && kbc->wakeup_key) {
			/*
			 * We can't report events directly from the ISR
			 * because timekeeping is stopped when processing
			 * wakeup request and we get a nasty warning when
			 * we try to call do_gettimeofday() in evdev
			 * handler.
			 */
			input_report_key(kbc->idev, kbc->wakeup_key, 1);
			input_sync(kbc->idev);
			input_report_key(kbc->idev, kbc->wakeup_key, 0);
			input_sync(kbc->idev);
		}
	} else if (input_device_enabled(kbc->idev)) {
		err = tegra_kbc_start(kbc);
		if (err)
			return err;
	}

	return 0;
}

static DEFINE_SIMPLE_DEV_PM_OPS(tegra_kbc_pm_ops,
				tegra_kbc_suspend, tegra_kbc_resume);

static struct platform_driver tegra_kbc_driver = {
	.probe		= tegra_kbc_probe,
	.driver	= {
		.name	= "tegra-kbc",
		.pm	= pm_sleep_ptr(&tegra_kbc_pm_ops),
		.of_match_table = tegra_kbc_of_match,
	},
};
module_platform_driver(tegra_kbc_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Rakesh Iyer <riyer@nvidia.com>");
MODULE_DESCRIPTION("Tegra matrix keyboard controller driver");
MODULE_ALIAS("platform:tegra-kbc");