Input: add PCF8574 I2C keypad input device driver

Signed-off-by: Bryan Wu <cooloney@kernel.org>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

3 files changed, 238 insertions, 0 deletions

diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
index 23140a3bb8e0..54a9c2d0ba1c 100644
--- a/drivers/input/misc/Kconfig
+++ b/drivers/input/misc/Kconfig
@@ -277,6 +277,16 @@ config INPUT_PCF50633_PMU
          Say Y to include support for delivering  PMU events via  input
          layer on NXP PCF50633.
 
+config INPUT_PCF8574
+        tristate "PCF8574 Keypad input device"
+        depends on I2C && EXPERIMENTAL
+        help
+          Say Y here if you want to support a keypad connetced via I2C
+          with a PCF8574.
+
+          To compile this driver as a module, choose M here: the
+          module will be called pcf8574_keypad.
+
 config INPUT_GPIO_ROTARY_ENCODER
         tristate "Rotary encoders connected to GPIO pins"
         depends on GPIOLIB && GENERIC_GPIO
diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
index 7e95a5d474dc..a662df21bf57 100644
--- a/drivers/input/misc/Makefile
+++ b/drivers/input/misc/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_INPUT_KEYSPAN_REMOTE)	+= keyspan_remote.o
 obj-$(CONFIG_INPUT_M68K_BEEP)           += m68kspkr.o
 obj-$(CONFIG_INPUT_PCAP)                += pcap_keys.o
 obj-$(CONFIG_INPUT_PCF50633_PMU)        += pcf50633-input.o
+obj-$(CONFIG_INPUT_PCF8574)             += pcf8574_keypad.o
 obj-$(CONFIG_INPUT_PCSPKR)              += pcspkr.o
 obj-$(CONFIG_INPUT_POWERMATE)           += powermate.o
 obj-$(CONFIG_INPUT_RB532_BUTTON)        += rb532_button.o
diff --git a/drivers/input/misc/pcf8574_keypad.c b/drivers/input/misc/pcf8574_keypad.c
new file mode 100644
index 000000000000..5c3ac4e0b055
--- /dev/null
+++ b/drivers/input/misc/pcf8574_keypad.c
@@ -0,0 +1,227 @@
+/*
+ * Driver for a keypad w/16 buttons connected to a PCF8574 I2C I/O expander
+ *
+ * Copyright 2005-2008 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2 or later.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/input.h>
+#include <linux/interrupt.h>
+#include <linux/i2c.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+
+#define DRV_NAME "pcf8574_keypad"
+
+static const unsigned char pcf8574_kp_btncode[] = {
+        [0] = KEY_RESERVED,
+        [1] = KEY_ENTER,
+        [2] = KEY_BACKSLASH,
+        [3] = KEY_0,
+        [4] = KEY_RIGHTBRACE,
+        [5] = KEY_C,
+        [6] = KEY_9,
+        [7] = KEY_8,
+        [8] = KEY_7,
+        [9] = KEY_B,
+        [10] = KEY_6,
+        [11] = KEY_5,
+        [12] = KEY_4,
+        [13] = KEY_A,
+        [14] = KEY_3,
+        [15] = KEY_2,
+        [16] = KEY_1
+};
+
+struct kp_data {
+        unsigned short btncode[ARRAY_SIZE(pcf8574_kp_btncode)];
+        struct input_dev *idev;
+        struct i2c_client *client;
+        char name[64];
+        char phys[32];
+        unsigned char laststate;
+};
+
+static short read_state(struct kp_data *lp)
+{
+        unsigned char x, y, a, b;
+
+        i2c_smbus_write_byte(lp->client, 240);
+        x = 0xF & (~(i2c_smbus_read_byte(lp->client) >> 4));
+
+        i2c_smbus_write_byte(lp->client, 15);
+        y = 0xF & (~i2c_smbus_read_byte(lp->client));
+
+        for (a = 0; x > 0; a++)
+                x = x >> 1;
+        for (b = 0; y > 0; b++)
+                y = y >> 1;
+
+        return ((a - 1) * 4) + b;
+}
+
+static irqreturn_t pcf8574_kp_irq_handler(int irq, void *dev_id)
+{
+        struct kp_data *lp = dev_id;
+        unsigned char nextstate = read_state(lp);
+
+        if (lp->laststate != nextstate) {
+                int key_down = nextstate <= ARRAY_SIZE(lp->btncode);
+                unsigned short keycode = key_down ?
+                        lp->btncode[nextstate] : lp->btncode[lp->laststate];
+
+                input_report_key(lp->idev, keycode, key_down);
+                input_sync(lp->idev);
+
+                lp->laststate = nextstate;
+        }
+
+        return IRQ_HANDLED;
+}
+
+static int __devinit pcf8574_kp_probe(struct i2c_client *client, const struct i2c_device_id *id)
+{
+        int i, ret;
+        struct input_dev *idev;
+        struct kp_data *lp;
+
+        if (i2c_smbus_write_byte(client, 240) < 0) {
+                dev_err(&client->dev, "probe: write fail\n");
+                return -ENODEV;
+        }
+
+        lp = kzalloc(sizeof(*lp), GFP_KERNEL);
+        if (!lp)
+                return -ENOMEM;
+
+        idev = input_allocate_device();
+        if (!idev) {
+                dev_err(&client->dev, "Can't allocate input device\n");
+                ret = -ENOMEM;
+                goto fail_allocate;
+        }
+
+        lp->idev = idev;
+        lp->client = client;
+
+        idev->evbit[0] = BIT_MASK(EV_KEY);
+        idev->keycode = lp->btncode;
+        idev->keycodesize = sizeof(lp->btncode[0]);
+        idev->keycodemax = ARRAY_SIZE(lp->btncode);
+
+        for (i = 0; i < ARRAY_SIZE(pcf8574_kp_btncode); i++) {
+                lp->btncode[i] = pcf8574_kp_btncode[i];
+                __set_bit(lp->btncode[i] & KEY_MAX, idev->keybit);
+        }
+
+        sprintf(lp->name, DRV_NAME);
+        sprintf(lp->phys, "kp_data/input0");
+
+        idev->name = lp->name;
+        idev->phys = lp->phys;
+        idev->id.bustype = BUS_I2C;
+        idev->id.vendor = 0x0001;
+        idev->id.product = 0x0001;
+        idev->id.version = 0x0100;
+
+        input_set_drvdata(idev, lp);
+
+        ret = input_register_device(idev);
+        if (ret) {
+                dev_err(&client->dev, "input_register_device() failed\n");
+                goto fail_register;
+        }
+
+        lp->laststate = read_state(lp);
+
+        ret = request_threaded_irq(client->irq, NULL, pcf8574_kp_irq_handler,
+                                   IRQF_TRIGGER_LOW | IRQF_ONESHOT,
+                                   DRV_NAME, lp);
+        if (ret) {
+                dev_err(&client->dev, "IRQ %d is not free\n", client->irq);
+                goto fail_irq;
+        }
+
+        i2c_set_clientdata(client, lp);
+        return 0;
+
+ fail_irq:
+        input_unregister_device(idev);
+ fail_register:
+        input_set_drvdata(idev, NULL);
+        input_free_device(idev);
+ fail_allocate:
+        kfree(lp);
+
+        return ret;
+}
+
+static int __devexit pcf8574_kp_remove(struct i2c_client *client)
+{
+        struct kp_data *lp = i2c_get_clientdata(client);
+
+        free_irq(client->irq, lp);
+
+        input_unregister_device(lp->idev);
+        kfree(lp);
+
+        i2c_set_clientdata(client, NULL);
+
+        return 0;
+}
+
+#ifdef CONFIG_PM
+static int pcf8574_kp_resume(struct i2c_client *client)
+{
+        enable_irq(client->irq);
+
+        return 0;
+}
+
+static int pcf8574_kp_suspend(struct i2c_client *client, pm_message_t mesg)
+{
+        disable_irq(client->irq);
+
+        return 0;
+}
+#else
+# define pcf8574_kp_resume  NULL
+# define pcf8574_kp_suspend NULL
+#endif
+
+static const struct i2c_device_id pcf8574_kp_id[] = {
+        { DRV_NAME, 0 },
+        { }
+};
+MODULE_DEVICE_TABLE(i2c, pcf8574_kp_id);
+
+static struct i2c_driver pcf8574_kp_driver = {
+        .driver = {
+                .name  = DRV_NAME,
+                .owner = THIS_MODULE,
+        },
+        .probe    = pcf8574_kp_probe,
+        .remove   = __devexit_p(pcf8574_kp_remove),
+        .suspend  = pcf8574_kp_suspend,
+        .resume   = pcf8574_kp_resume,
+        .id_table = pcf8574_kp_id,
+};
+
+static int __init pcf8574_kp_init(void)
+{
+        return i2c_add_driver(&pcf8574_kp_driver);
+}
+module_init(pcf8574_kp_init);
+
+static void __exit pcf8574_kp_exit(void)
+{
+        i2c_del_driver(&pcf8574_kp_driver);
+}
+module_exit(pcf8574_kp_exit);
+
+MODULE_AUTHOR("Michael Hennerich");
+MODULE_DESCRIPTION("Keypad input driver for 16 keys connected to PCF8574");
+MODULE_LICENSE("GPL");