Input: add imx-keypad driver to support the IMX Keypad Port

The IMX family of Application Processors is shipped with a Keypad Port
supported by this driver.

The peripheral can control up to an 8x8 matrix key pad where all the
scanning is done via software.  The hardware provides two interrupts:
one for key presses (KDI) and one for all key releases (KRI). There is
also a simple circuit for glitch reduction (said for synchronization)
made by two series of 3 D-latches clocked by the keypad-clock that
stabilize the interrupts sources. KDI and KRI are fired only if the
respective conditions are maintained for at last 4 keypad-clock cycle.

Since those circuits are poor for a correct debounce process (the
keypad-clock frequency is 32K and bounces longer than 94us are not
masked) the driver, when an interrupt arrives, samples the matrix
with a period of 10ms until the readins are stable for
IMX_KEYPAD_SCANS_FOR_STABILITY times (currently set at 3). After
getting stable result appropriate events are sent through the input
stack.

If some keys are maintained pressed, the driver continues to scan
the matrix with a longer period (60ms) to catch possible multiple
key presses without overloading the cpu. This process ends when all
keys are released.

This driver is tested to build in kernel or as a module and follow
the specification of Freescale Application processors:
i.MX25 i.MX27 i.MX31 i.MX35 i.MX51 especially tested on i.MX31.

Signed-off-by: Alberto Panizzo <maramaopercheseimorto@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

3 files changed, 604 insertions, 0 deletions

diff --git a/drivers/input/keyboard/Kconfig b/drivers/input/keyboard/Kconfig
index c72283c6916..616a3916d18 100644
--- a/drivers/input/keyboard/Kconfig
+++ b/drivers/input/keyboard/Kconfig
@@ -292,6 +292,15 @@ config KEYBOARD_MAX7359
           To compile this driver as a module, choose M here: the
           module will be called max7359_keypad.
 
+config KEYBOARD_IMX
+        tristate "IMX keypad support"
+        depends on ARCH_MXC
+        help
+          Enable support for IMX keypad port.
+
+          To compile this driver as a module, choose M here: the
+          module will be called imx_keypad.
+
 config KEYBOARD_NEWTON
         tristate "Newton keyboard"
         select SERIO
diff --git a/drivers/input/keyboard/Makefile b/drivers/input/keyboard/Makefile
index 78654ef6520..706c6b5ed5f 100644
--- a/drivers/input/keyboard/Makefile
+++ b/drivers/input/keyboard/Makefile
@@ -17,6 +17,7 @@ obj-$(CONFIG_KEYBOARD_EP93XX)		+= ep93xx_keypad.o
 obj-$(CONFIG_KEYBOARD_GPIO)             += gpio_keys.o
 obj-$(CONFIG_KEYBOARD_HIL)              += hil_kbd.o
 obj-$(CONFIG_KEYBOARD_HIL_OLD)          += hilkbd.o
+obj-$(CONFIG_KEYBOARD_IMX)              += imx_keypad.o
 obj-$(CONFIG_KEYBOARD_HP6XX)            += jornada680_kbd.o
 obj-$(CONFIG_KEYBOARD_HP7XX)            += jornada720_kbd.o
 obj-$(CONFIG_KEYBOARD_LKKBD)            += lkkbd.o
diff --git a/drivers/input/keyboard/imx_keypad.c b/drivers/input/keyboard/imx_keypad.c
new file mode 100644
index 00000000000..2ee5b798024
--- /dev/null
+++ b/drivers/input/keyboard/imx_keypad.c
@@ -0,0 +1,594 @@
+/*
+ * Driver for the IMX keypad port.
+ * Copyright (C) 2009 Alberto Panizzo <maramaopercheseimorto@gmail.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.
+ *
+ * <<Power management needs to be implemented>>.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/input/matrix_keypad.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/timer.h>
+
+/*
+ * Keypad Controller registers (halfword)
+ */
+#define KPCR            0x00 /* Keypad Control Register */
+
+#define KPSR            0x02 /* Keypad Status Register */
+#define KBD_STAT_KPKD   (0x1 << 0) /* Key Press Interrupt Status bit (w1c) */
+#define KBD_STAT_KPKR   (0x1 << 1) /* Key Release Interrupt Status bit (w1c) */
+#define KBD_STAT_KDSC   (0x1 << 2) /* Key Depress Synch Chain Status bit (w1c)*/
+#define KBD_STAT_KRSS   (0x1 << 3) /* Key Release Synch Status bit (w1c)*/
+#define KBD_STAT_KDIE   (0x1 << 8) /* Key Depress Interrupt Enable Status bit */
+#define KBD_STAT_KRIE   (0x1 << 9) /* Key Release Interrupt Enable */
+#define KBD_STAT_KPPEN  (0x1 << 10) /* Keypad Clock Enable */
+
+#define KDDR            0x04 /* Keypad Data Direction Register */
+#define KPDR            0x06 /* Keypad Data Register */
+
+#define MAX_MATRIX_KEY_ROWS     8
+#define MAX_MATRIX_KEY_COLS     8
+#define MATRIX_ROW_SHIFT        3
+
+#define MAX_MATRIX_KEY_NUM      (MAX_MATRIX_KEY_ROWS * MAX_MATRIX_KEY_COLS)
+
+struct imx_keypad {
+
+        struct clk *clk;
+        struct input_dev *input_dev;
+        void __iomem *mmio_base;
+
+        int                     irq;
+        struct timer_list       check_matrix_timer;
+
+        /*
+         * The matrix is stable only if no changes are detected after
+         * IMX_KEYPAD_SCANS_FOR_STABILITY scans
+         */
+#define IMX_KEYPAD_SCANS_FOR_STABILITY 3
+        int                     stable_count;
+
+        bool                    enabled;
+
+        /* Masks for enabled rows/cols */
+        unsigned short          rows_en_mask;
+        unsigned short          cols_en_mask;
+
+        unsigned short          keycodes[MAX_MATRIX_KEY_NUM];
+
+        /*
+         * Matrix states:
+         * -stable: achieved after a complete debounce process.
+         * -unstable: used in the debouncing process.
+         */
+        unsigned short          matrix_stable_state[MAX_MATRIX_KEY_COLS];
+        unsigned short          matrix_unstable_state[MAX_MATRIX_KEY_COLS];
+};
+
+/* Scan the matrix and return the new state in *matrix_volatile_state. */
+static void imx_keypad_scan_matrix(struct imx_keypad *keypad,
+                                  unsigned short *matrix_volatile_state)
+{
+        int col;
+        unsigned short reg_val;
+
+        for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
+                if ((keypad->cols_en_mask & (1 << col)) == 0)
+                        continue;
+                /*
+                 * Discharge keypad capacitance:
+                 * 2. write 1s on column data.
+                 * 3. configure columns as totem-pole to discharge capacitance.
+                 * 4. configure columns as open-drain.
+                 */
+                reg_val = readw(keypad->mmio_base + KPDR);
+                reg_val |= 0xff00;
+                writew(reg_val, keypad->mmio_base + KPDR);
+
+                reg_val = readw(keypad->mmio_base + KPCR);
+                reg_val &= ~((keypad->cols_en_mask & 0xff) << 8);
+                writew(reg_val, keypad->mmio_base + KPCR);
+
+                udelay(2);
+
+                reg_val = readw(keypad->mmio_base + KPCR);
+                reg_val |= (keypad->cols_en_mask & 0xff) << 8;
+                writew(reg_val, keypad->mmio_base + KPCR);
+
+                /*
+                 * 5. Write a single column to 0, others to 1.
+                 * 6. Sample row inputs and save data.
+                 * 7. Repeat steps 2 - 6 for remaining columns.
+                 */
+                reg_val = readw(keypad->mmio_base + KPDR);
+                reg_val &= ~(1 << (8 + col));
+                writew(reg_val, keypad->mmio_base + KPDR);
+
+                /*
+                 * Delay added to avoid propagating the 0 from column to row
+                 * when scanning.
+                 */
+                udelay(5);
+
+                /*
+                 * 1s in matrix_volatile_state[col] means key pressures
+                 * throw data from non enabled rows.
+                 */
+                reg_val = readw(keypad->mmio_base + KPDR);
+                matrix_volatile_state[col] = (~reg_val) & keypad->rows_en_mask;
+        }
+
+        /*
+         * Return in standby mode:
+         * 9. write 0s to columns
+         */
+        reg_val = readw(keypad->mmio_base + KPDR);
+        reg_val &= 0x00ff;
+        writew(reg_val, keypad->mmio_base + KPDR);
+}
+
+/*
+ * Compare the new matrix state (volatile) with the stable one stored in
+ * keypad->matrix_stable_state and fire events if changes are detected.
+ */
+static void imx_keypad_fire_events(struct imx_keypad *keypad,
+                                   unsigned short *matrix_volatile_state)
+{
+        struct input_dev *input_dev = keypad->input_dev;
+        int row, col;
+
+        for (col = 0; col < MAX_MATRIX_KEY_COLS; col++) {
+                unsigned short bits_changed;
+                int code;
+
+                if ((keypad->cols_en_mask & (1 << col)) == 0)
+                        continue; /* Column is not enabled */
+
+                bits_changed = keypad->matrix_stable_state[col] ^
+                                                matrix_volatile_state[col];
+
+                if (bits_changed == 0)
+                        continue; /* Column does not contain changes */
+
+                for (row = 0; row < MAX_MATRIX_KEY_ROWS; row++) {
+                        if ((keypad->rows_en_mask & (1 << row)) == 0)
+                                continue; /* Row is not enabled */
+                        if ((bits_changed & (1 << row)) == 0)
+                                continue; /* Row does not contain changes */
+
+                        code = MATRIX_SCAN_CODE(row, col, MATRIX_ROW_SHIFT);
+                        input_event(input_dev, EV_MSC, MSC_SCAN, code);
+                        input_report_key(input_dev, keypad->keycodes[code],
+                                matrix_volatile_state[col] & (1 << row));
+                        dev_dbg(&input_dev->dev, "Event code: %d, val: %d",
+                                keypad->keycodes[code],
+                                matrix_volatile_state[col] & (1 << row));
+                }
+        }
+        input_sync(input_dev);
+}
+
+/*
+ * imx_keypad_check_for_events is the timer handler.
+ */
+static void imx_keypad_check_for_events(unsigned long data)
+{
+        struct imx_keypad *keypad = (struct imx_keypad *) data;
+        unsigned short matrix_volatile_state[MAX_MATRIX_KEY_COLS];
+        unsigned short reg_val;
+        bool state_changed, is_zero_matrix;
+        int i;
+
+        memset(matrix_volatile_state, 0, sizeof(matrix_volatile_state));
+
+        imx_keypad_scan_matrix(keypad, matrix_volatile_state);
+
+        state_changed = false;
+        for (i = 0; i < MAX_MATRIX_KEY_COLS; i++) {
+                if ((keypad->cols_en_mask & (1 << i)) == 0)
+                        continue;
+
+                if (keypad->matrix_unstable_state[i] ^ matrix_volatile_state[i]) {
+                        state_changed = true;
+                        break;
+                }
+        }
+
+        /*
+         * If the matrix state is changed from the previous scan
+         *   (Re)Begin the debouncing process, saving the new state in
+         *    keypad->matrix_unstable_state.
+         * else
+         *   Increase the count of number of scans with a stable state.
+         */
+        if (state_changed) {
+                memcpy(keypad->matrix_unstable_state, matrix_volatile_state,
+                        sizeof(matrix_volatile_state));
+                keypad->stable_count = 0;
+        } else
+                keypad->stable_count++;
+
+        /*
+         * If the matrix is not as stable as we want reschedule scan
+         * in the near future.
+         */
+        if (keypad->stable_count < IMX_KEYPAD_SCANS_FOR_STABILITY) {
+                mod_timer(&keypad->check_matrix_timer,
+                          jiffies + msecs_to_jiffies(10));
+                return;
+        }
+
+        /*
+         * If the matrix state is stable, fire the events and save the new
+         * stable state. Note, if the matrix is kept stable for longer
+         * (keypad->stable_count > IMX_KEYPAD_SCANS_FOR_STABILITY) all
+         * events have already been generated.
+         */
+        if (keypad->stable_count == IMX_KEYPAD_SCANS_FOR_STABILITY) {
+                imx_keypad_fire_events(keypad, matrix_volatile_state);
+
+                memcpy(keypad->matrix_stable_state, matrix_volatile_state,
+                        sizeof(matrix_volatile_state));
+        }
+
+        is_zero_matrix = true;
+        for (i = 0; i < MAX_MATRIX_KEY_COLS; i++) {
+                if (matrix_volatile_state[i] != 0) {
+                        is_zero_matrix = false;
+                        break;
+                }
+        }
+
+
+        if (is_zero_matrix) {
+                /*
+                 * All keys have been released. Enable only the KDI
+                 * interrupt for future key presses (clear the KDI
+                 * status bit and its sync chain before that).
+                 */
+                reg_val = readw(keypad->mmio_base + KPSR);
+                reg_val |= KBD_STAT_KPKD | KBD_STAT_KDSC;
+                writew(reg_val, keypad->mmio_base + KPSR);
+
+                reg_val = readw(keypad->mmio_base + KPSR);
+                reg_val |= KBD_STAT_KDIE;
+                reg_val &= ~KBD_STAT_KRIE;
+                writew(reg_val, keypad->mmio_base + KPSR);
+        } else {
+                /*
+                 * Some keys are still pressed. Schedule a rescan in
+                 * attempt to detect multiple key presses and enable
+                 * the KRI interrupt to react quickly to key release
+                 * event.
+                 */
+                mod_timer(&keypad->check_matrix_timer,
+                          jiffies + msecs_to_jiffies(60));
+
+                reg_val = readw(keypad->mmio_base + KPSR);
+                reg_val |= KBD_STAT_KPKR | KBD_STAT_KRSS;
+                writew(reg_val, keypad->mmio_base + KPSR);
+
+                reg_val = readw(keypad->mmio_base + KPSR);
+                reg_val |= KBD_STAT_KRIE;
+                reg_val &= ~KBD_STAT_KDIE;
+                writew(reg_val, keypad->mmio_base + KPSR);
+        }
+}
+
+static irqreturn_t imx_keypad_irq_handler(int irq, void *dev_id)
+{
+        struct imx_keypad *keypad = dev_id;
+        unsigned short reg_val;
+
+        reg_val = readw(keypad->mmio_base + KPSR);
+
+        /* Disable both interrupt types */
+        reg_val &= ~(KBD_STAT_KRIE | KBD_STAT_KDIE);
+        /* Clear interrupts status bits */
+        reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD;
+        writew(reg_val, keypad->mmio_base + KPSR);
+
+        if (keypad->enabled) {
+                /* The matrix is supposed to be changed */
+                keypad->stable_count = 0;
+
+                /* Schedule the scanning procedure near in the future */
+                mod_timer(&keypad->check_matrix_timer,
+                          jiffies + msecs_to_jiffies(2));
+        }
+
+        return IRQ_HANDLED;
+}
+
+static void imx_keypad_config(struct imx_keypad *keypad)
+{
+        unsigned short reg_val;
+
+        /*
+         * Include enabled rows in interrupt generation (KPCR[7:0])
+         * Configure keypad columns as open-drain (KPCR[15:8])
+         */
+        reg_val = readw(keypad->mmio_base + KPCR);
+        reg_val |= keypad->rows_en_mask & 0xff;         /* rows */
+        reg_val |= (keypad->cols_en_mask & 0xff) << 8;  /* cols */
+        writew(reg_val, keypad->mmio_base + KPCR);
+
+        /* Write 0's to KPDR[15:8] (Colums) */
+        reg_val = readw(keypad->mmio_base + KPDR);
+        reg_val &= 0x00ff;
+        writew(reg_val, keypad->mmio_base + KPDR);
+
+        /* Configure columns as output, rows as input (KDDR[15:0]) */
+        writew(0xff00, keypad->mmio_base + KDDR);
+
+        /*
+         * Clear Key Depress and Key Release status bit.
+         * Clear both synchronizer chain.
+         */
+        reg_val = readw(keypad->mmio_base + KPSR);
+        reg_val |= KBD_STAT_KPKR | KBD_STAT_KPKD |
+                   KBD_STAT_KDSC | KBD_STAT_KRSS;
+        writew(reg_val, keypad->mmio_base + KPSR);
+
+        /* Enable KDI and disable KRI (avoid false release events). */
+        reg_val |= KBD_STAT_KDIE;
+        reg_val &= ~KBD_STAT_KRIE;
+        writew(reg_val, keypad->mmio_base + KPSR);
+}
+
+static void imx_keypad_inhibit(struct imx_keypad *keypad)
+{
+        unsigned short reg_val;
+
+        /* Inhibit KDI and KRI interrupts. */
+        reg_val = readw(keypad->mmio_base + KPSR);
+        reg_val &= ~(KBD_STAT_KRIE | KBD_STAT_KDIE);
+        writew(reg_val, keypad->mmio_base + KPSR);
+
+        /* Colums as open drain and disable all rows */
+        writew(0xff00, keypad->mmio_base + KPCR);
+}
+
+static void imx_keypad_close(struct input_dev *dev)
+{
+        struct imx_keypad *keypad = input_get_drvdata(dev);
+
+        dev_dbg(&dev->dev, ">%s\n", __func__);
+
+        /* Mark keypad as being inactive */
+        keypad->enabled = false;
+        synchronize_irq(keypad->irq);
+        del_timer_sync(&keypad->check_matrix_timer);
+
+        imx_keypad_inhibit(keypad);
+
+        /* Disable clock unit */
+        clk_disable(keypad->clk);
+}
+
+static int imx_keypad_open(struct input_dev *dev)
+{
+        struct imx_keypad *keypad = input_get_drvdata(dev);
+
+        dev_dbg(&dev->dev, ">%s\n", __func__);
+
+        /* We became active from now */
+        keypad->enabled = true;
+
+        /* Enable the kpp clock */
+        clk_enable(keypad->clk);
+        imx_keypad_config(keypad);
+
+        /* Sanity control, not all the rows must be actived now. */
+        if ((readw(keypad->mmio_base + KPDR) & keypad->rows_en_mask) == 0) {
+                dev_err(&dev->dev,
+                        "too many keys pressed, control pins initialisation\n");
+                goto open_err;
+        }
+
+        return 0;
+
+open_err:
+        imx_keypad_close(dev);
+        return -EIO;
+}
+
+static int __devinit imx_keypad_probe(struct platform_device *pdev)
+{
+        const struct matrix_keymap_data *keymap_data = pdev->dev.platform_data;
+        struct imx_keypad *keypad;
+        struct input_dev *input_dev;
+        struct resource *res;
+        int irq, error, i;
+
+        if (keymap_data == NULL) {
+                dev_err(&pdev->dev, "no keymap defined\n");
+                return -EINVAL;
+        }
+
+        irq = platform_get_irq(pdev, 0);
+        if (irq < 0) {
+                dev_err(&pdev->dev, "no irq defined in platform data\n");
+                return -EINVAL;
+        }
+
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        if (res == NULL) {
+                dev_err(&pdev->dev, "no I/O memory defined in platform data\n");
+                return -EINVAL;
+        }
+
+        res = request_mem_region(res->start, resource_size(res), pdev->name);
+        if (res == NULL) {
+                dev_err(&pdev->dev, "failed to request I/O memory\n");
+                return -EBUSY;
+        }
+
+        input_dev = input_allocate_device();
+        if (!input_dev) {
+                dev_err(&pdev->dev, "failed to allocate the input device\n");
+                error = -ENOMEM;
+                goto failed_rel_mem;
+        }
+
+        keypad = kzalloc(sizeof(struct imx_keypad), GFP_KERNEL);
+        if (!keypad) {
+                dev_err(&pdev->dev, "not enough memory for driver data\n");
+                error = -ENOMEM;
+                goto failed_free_input;
+        }
+
+        keypad->input_dev = input_dev;
+        keypad->irq = irq;
+        keypad->stable_count = 0;
+
+        setup_timer(&keypad->check_matrix_timer,
+                    imx_keypad_check_for_events, (unsigned long) keypad);
+
+        keypad->mmio_base = ioremap(res->start, resource_size(res));
+        if (keypad->mmio_base == NULL) {
+                dev_err(&pdev->dev, "failed to remap I/O memory\n");
+                error = -ENOMEM;
+                goto failed_free_priv;
+        }
+
+        keypad->clk = clk_get(&pdev->dev, "kpp");
+        if (IS_ERR(keypad->clk)) {
+                dev_err(&pdev->dev, "failed to get keypad clock\n");
+                error = PTR_ERR(keypad->clk);
+                goto failed_unmap;
+        }
+
+        /* Search for rows and cols enabled */
+        for (i = 0; i < keymap_data->keymap_size; i++) {
+                keypad->rows_en_mask |= 1 << KEY_ROW(keymap_data->keymap[i]);
+                keypad->cols_en_mask |= 1 << KEY_COL(keymap_data->keymap[i]);
+        }
+
+        if (keypad->rows_en_mask > ((1 << MAX_MATRIX_KEY_ROWS) - 1) ||
+           keypad->cols_en_mask > ((1 << MAX_MATRIX_KEY_COLS) - 1)) {
+                dev_err(&pdev->dev,
+                        "invalid key data (too many rows or colums)\n");
+                error = -EINVAL;
+                goto failed_clock_put;
+        }
+        dev_dbg(&pdev->dev, "enabled rows mask: %x\n", keypad->rows_en_mask);
+        dev_dbg(&pdev->dev, "enabled cols mask: %x\n", keypad->cols_en_mask);
+
+        /* Init the Input device */
+        input_dev->name = pdev->name;
+        input_dev->id.bustype = BUS_HOST;
+        input_dev->dev.parent = &pdev->dev;
+        input_dev->open = imx_keypad_open;
+        input_dev->close = imx_keypad_close;
+        input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_REP);
+        input_dev->keycode = keypad->keycodes;
+        input_dev->keycodesize = sizeof(keypad->keycodes[0]);
+        input_dev->keycodemax = ARRAY_SIZE(keypad->keycodes);
+
+        matrix_keypad_build_keymap(keymap_data, MATRIX_ROW_SHIFT,
+                                keypad->keycodes, input_dev->keybit);
+
+        input_set_capability(input_dev, EV_MSC, MSC_SCAN);
+        input_set_drvdata(input_dev, keypad);
+
+        /* Ensure that the keypad will stay dormant until opened */
+        imx_keypad_inhibit(keypad);
+
+        error = request_irq(irq, imx_keypad_irq_handler, IRQF_DISABLED,
+                            pdev->name, keypad);
+        if (error) {
+                dev_err(&pdev->dev, "failed to request IRQ\n");
+                goto failed_clock_put;
+        }
+
+        /* Register the input device */
+        error = input_register_device(input_dev);
+        if (error) {
+                dev_err(&pdev->dev, "failed to register input device\n");
+                goto failed_free_irq;
+        }
+
+        platform_set_drvdata(pdev, keypad);
+        device_init_wakeup(&pdev->dev, 1);
+
+        return 0;
+
+failed_free_irq:
+        free_irq(irq, pdev);
+failed_clock_put:
+        clk_put(keypad->clk);
+failed_unmap:
+        iounmap(keypad->mmio_base);
+failed_free_priv:
+        kfree(keypad);
+failed_free_input:
+        input_free_device(input_dev);
+failed_rel_mem:
+        release_mem_region(res->start, resource_size(res));
+        return error;
+}
+
+static int __devexit imx_keypad_remove(struct platform_device *pdev)
+{
+        struct imx_keypad *keypad = platform_get_drvdata(pdev);
+        struct resource *res;
+
+        dev_dbg(&pdev->dev, ">%s\n", __func__);
+
+        platform_set_drvdata(pdev, NULL);
+
+        input_unregister_device(keypad->input_dev);
+
+        free_irq(keypad->irq, keypad);
+        clk_put(keypad->clk);
+
+        iounmap(keypad->mmio_base);
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        release_mem_region(res->start, resource_size(res));
+
+        kfree(keypad);
+
+        return 0;
+}
+
+static struct platform_driver imx_keypad_driver = {
+        .driver         = {
+                .name   = "imx-keypad",
+                .owner  = THIS_MODULE,
+        },
+        .probe          = imx_keypad_probe,
+        .remove         = __devexit_p(imx_keypad_remove),
+};
+
+static int __init imx_keypad_init(void)
+{
+        return platform_driver_register(&imx_keypad_driver);
+}
+
+static void __exit imx_keypad_exit(void)
+{
+        platform_driver_unregister(&imx_keypad_driver);
+}
+
+module_init(imx_keypad_init);
+module_exit(imx_keypad_exit);
+
+MODULE_AUTHOR("Alberto Panizzo <maramaopercheseimorto@gmail.com>");
+MODULE_DESCRIPTION("IMX Keypad Port Driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:imx-keypad");