This driver adds support for Nintendo Wiimote extension controllers
directly attached to an i2c bus, such as when using an adaptor like
the Wiichuck.

v3: - Fixed and tested classic controller connection
   - Fixed comment block
v2: - Fixed DMA buffers on stack problem
   - added classic controller support

Signed-off-by: Grant Likely <redacted>
---
I've actually got my hands on a classic controller now, so this driver
has been tested with both nunchuck and classic controller.  I leave adding
support for the motionplus to someone who actually has the hardware.  :)

This driver should be ready for merging now.

g.

 drivers/input/joystick/Kconfig    |   13 +
 drivers/input/joystick/Makefile   |    1
 drivers/input/joystick/wiichuck.c |  435 +++++++++++++++++++++++++++++++++++++
 3 files changed, 449 insertions(+), 0 deletions(-)
 create mode 100644 drivers/input/joystick/wiichuck.c

diff --git a/drivers/input/joystick/Kconfig b/drivers/input/joystick/Kconfig
index 56eb471..5b7fba7 100644
--- a/drivers/input/joystick/Kconfig
+++ b/drivers/input/joystick/Kconfig

@@ -193,6 +193,19 @@ config JOYSTICK_TWIDJOY

         To compile this driver as a module, choose M here: the
         module will be called twidjoy.

+config JOYSTICK_WIICHUCK
+       tristate "Nintendo Wiimote Extension connector on i2c bus"
+       depends on I2C
+       select INPUT_POLLDEV
+       help
+         Say Y here if you have a Nintendo Wiimote extension connector
+         attached directly to an i2c bus, like the Sparcfun Wiichuck adapter
+         board.  This driver supports both the Nunchuck and the Classic
+         Controller extensions.
+
+         To compile this driver as a module, choose M here: the
+         modules will be called wiichuck.
+
 config JOYSTICK_ZHENHUA
       tristate "5-byte Zhenhua RC transmitter"
       select SERIO

diff --git a/drivers/input/joystick/Makefile b/drivers/input/joystick/Makefile
index 92dc0de..78466d6 100644
--- a/drivers/input/joystick/Makefile
+++ b/drivers/input/joystick/Makefile

@@ -29,6 +29,7 @@ obj-$(CONFIG_JOYSTICK_TMDC)           += tmdc.o

 obj-$(CONFIG_JOYSTICK_TURBOGRAFX)      += turbografx.o
 obj-$(CONFIG_JOYSTICK_TWIDJOY)         += twidjoy.o
 obj-$(CONFIG_JOYSTICK_WARRIOR)         += warrior.o
+obj-$(CONFIG_JOYSTICK_WIICHUCK)                += wiichuck.o
 obj-$(CONFIG_JOYSTICK_XPAD)            += xpad.o
 obj-$(CONFIG_JOYSTICK_ZHENHUA)         += zhenhua.o
 obj-$(CONFIG_JOYSTICK_WALKERA0701)     += walkera0701.o

diff --git a/drivers/input/joystick/wiichuck.c b/drivers/input/joystick/wiichuck.c
new file mode 100644
index 0000000..ab26c34b
--- /dev/null
+++ b/drivers/input/joystick/wiichuck.c

@@ -0,0 +1,435 @@
+/*
+ * i2c Wiichuck driver (Nintendo Wiimote accessory connector)
+ *
+ * This driver supports Nintendo Wiimote accessories like the Nunchuck and
+ * the Classic Controller connected to an i2c bus.
+ *
+ * Copyright (c) 2011 Secret Lab Technologies Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * This driver uses the polled input device abstraction to implement an
+ * input driver for Nintendo expansion devices wired up to an i2c bus.
+ *
+ * A state machine implements the protocol handling.  It starts in the
+ * DISCONNECTED state initially and polls every second waiting for a
+ * device to get attached, and reading the device id when one does.
+ * If the device is recognized, then the polling period is bumped
+ * to 100ms, and the state machine enters into a loop reading the data
+ * capture reports out of the controller.  If at any time the device
+ * is disconnected, then it goes back to DISCONNECTED state and bumps
+ * the polling frequency back to 1 second.
+ *
+ * A callback is implemented for each supported devices, currently the
+ * Nunchuck and the Classic Controller.  Wii Motion Plus has yet to be
+ * added.
+ */
+
+#include <linux/cache.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/input.h>
+#include <linux/input-polldev.h>
+#include <linux/mod_devicetable.h>
+#include <linux/slab.h>
+
+MODULE_AUTHOR("Grant Likely <grant.likely@secretlab.ca>");
+MODULE_DESCRIPTION("Wiichuck (i2c Nintendo Wiimote accessory) driver");
+MODULE_LICENSE("GPL");
+
+#define WIICHUCK_POLL_PERIOD   (1000)  /* 1 second */
+#ifdef DEBUG
+#define WIICHUCK_CAPTURE_PERIOD (500)  /* 1/2 second for debug */
+#else
+#define WIICHUCK_CAPTURE_PERIOD (100)  /* 100 milliseconds */
+#endif /* DEBUG */
+
+enum wiichuck_state {
+       WIICHUCK_STATE_DISCONNECTED = 0,
+       WIICHUCK_STATE_DATA,
+};
+
+struct wiichuck_device {
+       struct input_polled_dev *poll_dev;
+       struct i2c_client *i2c_client;
+       int (*process)(struct wiichuck_device *wiichuck);
+       enum wiichuck_state state;
+
+       /* transfer buffer, aligned to cache line so it can be used with DMA */
+       uint8_t buf[6] ____cacheline_aligned;
+};
+
+static int wiichuck_transfer(struct wiichuck_device *wiichuck,
+                            int len, bool read)
+{
+       struct i2c_client *i2c = wiichuck->i2c_client;
+       struct i2c_msg msg = {
+               .addr = i2c->addr, .len = len, .buf = wiichuck->buf };
+
+       if (read)
+               msg.flags = I2C_M_RD;
+       return i2c_transfer(i2c->adapter, &msg, 1);
+}
+
+static int wiichuck_write(struct wiichuck_device *wiichuck,
+                          uint8_t addr, uint8_t val)
+{
+       wiichuck->buf[0] = addr;
+       wiichuck->buf[1] = val;
+       return wiichuck_transfer(wiichuck, 2, false);
+}
+
+static inline int wiichuck_setaddr(struct wiichuck_device *wiichuck,
+                                   uint8_t addr)
+{
+       wiichuck->buf[0] = addr;
+       return wiichuck_transfer(wiichuck, 1, false);
+}
+
+static inline int wiichuck_read(struct wiichuck_device *wiichuck, int len)
+{
+       return wiichuck_transfer(wiichuck, len, true);
+}
+
+static inline bool WIIBTN(int val, int bit)
+{
+       return (val & BIT(bit)) == 0;
+}
+
+static int wiichuck_process_unknown(struct wiichuck_device *wiichuck)
+{
+       return 0;
+}
+
+static int wiichuck_process_nunchuck(struct wiichuck_device *wiichuck)
+{
+       struct input_dev *input_dev = wiichuck->poll_dev->input;
+       uint8_t *b = wiichuck->buf;
+       int ax, ay, az, rc;
+
+       rc = wiichuck_read(wiichuck, 6);
+       if (rc < 0)
+               return rc;
+
+       ax = (b[2] << 2) | ((b[5] >> 2) & 0x3);
+       ay = (b[3] << 2) | ((b[5] >> 4) & 0x3);
+       az = (b[4] << 2) | ((b[5] >> 6) & 0x3);
+
+       input_report_abs(input_dev, ABS_X, b[0]);
+       input_report_abs(input_dev, ABS_Y, b[1]);
+       input_report_abs(input_dev, ABS_RX, ax);
+       input_report_abs(input_dev, ABS_RY, ax);
+       input_report_abs(input_dev, ABS_RZ, ay);
+       input_report_key(input_dev, BTN_C, WIIBTN(b[5], 1));
+       input_report_key(input_dev, BTN_Z, WIIBTN(b[5], 0));
+       input_sync(input_dev);
+
+       dev_dbg(&wiichuck->i2c_client->dev,
+               "nunchuck: j=%.3i,%.3i a=%.3x,%.3x,%.3x c,z=%i,%i\n",
+               b[0],b[1], ax,ay,az, WIIBTN(b[5], 1), WIIBTN(b[5], 0));
+       return 0;
+};
+
+static int wiichuck_process_classic(struct wiichuck_device *wiichuck)
+{
+       struct input_dev *input_dev = wiichuck->poll_dev->input;
+       uint8_t *b = wiichuck->buf;
+       int lx, ly, lt, rx, ry, rt, rc;
+
+       rc = wiichuck_read(wiichuck, 6);
+       if (rc < 0)
+               return rc;
+
+       /* Analog measurements; some values are split between registers */
+       rx = ((b[0] >> 3) & 0x18) | ((b[1] >> 5) & 6) | ((b[2] >> 7) & 1);
+       ry = b[2] & 0x1f;
+       rt = b[3] & 0x1f;
+       lx = b[0] & 0x3f;
+       ly = b[1] & 0x3f;
+       lt = ((b[2] >> 2) & 0x18) | ((b[3] >> 5) & 7);
+
+       input_report_abs(input_dev, ABS_HAT0X, lx); /* left joystick */
+       input_report_abs(input_dev, ABS_HAT0Y, ly);
+       input_report_abs(input_dev, ABS_BRAKE, lt); /* left trigger */
+       input_report_abs(input_dev, ABS_HAT1X, rx); /* right joystick */
+       input_report_abs(input_dev, ABS_HAT1Y, ry);
+       input_report_abs(input_dev, ABS_GAS, rt); /* right trigger */
+
+       /* D-pad */
+       input_report_abs(input_dev, ABS_HAT2X, WIIBTN(b[4],7) - WIIBTN(b[5],1));
+       input_report_abs(input_dev, ABS_HAT2Y, WIIBTN(b[4],6) - WIIBTN(b[5],0));
+
+       /* Buttons */
+       input_report_key(input_dev, BTN_TL, WIIBTN(b[4], 5)); /* left trigger */
+       input_report_key(input_dev, BTN_SELECT, WIIBTN(b[4], 4)); /* minus */
+       input_report_key(input_dev, BTN_MODE, WIIBTN(b[4], 3)); /* home */
+       input_report_key(input_dev, BTN_START, WIIBTN(b[4], 2)); /* plus */
+       input_report_key(input_dev, BTN_TR, WIIBTN(b[4], 1)); /* right trigger */
+
+       input_report_key(input_dev, BTN_TL2, WIIBTN(b[5], 7)); /* left z */
+       input_report_key(input_dev, BTN_B, WIIBTN(b[5], 6));
+       input_report_key(input_dev, BTN_Y, WIIBTN(b[5], 5));
+       input_report_key(input_dev, BTN_A, WIIBTN(b[5], 4));
+       input_report_key(input_dev, BTN_X, WIIBTN(b[5], 3));
+       input_report_key(input_dev, BTN_TR2, WIIBTN(b[5], 2)); /* right z */
+       input_sync(input_dev);
+
+       dev_dbg(&wiichuck->i2c_client->dev,
+               "classic: r=%.3i,%.3i,%.3i l=%.3x,%.3x,%.3x b=%.2x,%.2x\n",
+               lx,ly,lt, rx,ry,rt, b[4],b[5]);
+       return 0;
+};
+
+/**
+ * wiichuck_poll() - Protocol state machine implementation
+ *
+ * A state machine is used here to keep the protocol processing
+ * reentrant.  Any of the i2c transactions will indeed sleep because
+ * i2c transactions are slow, but there is a mandatory delay between
+ * triggering the data capture (set address) and reading the data
+ * back.  Using a state machine means the poll function can return and
+ * free up the worker thread while waiting for the data.
+ */
+static void wiichuck_poll(struct input_polled_dev *poll_dev)
+{
+       struct wiichuck_device *wiichuck = poll_dev->private;
+       int id;
+
+       switch (wiichuck->state) {
+       case WIICHUCK_STATE_DISCONNECTED:
+               /* Disable encryption */
+               if (wiichuck_write(wiichuck, 0xf0, 0x55) < 0)
+                       return;
+               if (wiichuck_write(wiichuck, 0xfb, 0x00) < 0)
+                       return;
+
+               /* Read device id */
+               if (wiichuck_setaddr(wiichuck, 0xfe) < 0)
+                       return;
+               if (wiichuck_read(wiichuck, 2) < 0)
+                       return;
+               id = (wiichuck->buf[0] << 8) | wiichuck->buf[1];
+
+               switch (id) {
+                       case 0x0000: /* Nunchuck */
+                               wiichuck->process = wiichuck_process_nunchuck;
+                               dev_info(&wiichuck->i2c_client->dev,
+                                        "Connected Nunchuck\n");
+                               break;
+
+                       case 0x0101: /* Classic Controller */
+                               wiichuck->process = wiichuck_process_classic;
+                               dev_info(&wiichuck->i2c_client->dev,
+                                        "Connected Classic Controller\n");
+                               break;
+
+                       default: /* No connection or unsupported device */
+                               wiichuck->process = wiichuck_process_unknown;
+                               dev_dbg(&wiichuck->i2c_client->dev,
+                                        "Connected unknown id: %x\n", id);
+                               return;
+               }
+
+               /* Setup the first data transfer */
+               if (wiichuck_setaddr(wiichuck, 0) < 0)
+                       return;
+
+               wiichuck->state = WIICHUCK_STATE_DATA;
+               poll_dev->poll_interval = WIICHUCK_CAPTURE_PERIOD;
+               break;
+
+       case WIICHUCK_STATE_DATA:
+               /* Read the input report */
+               if (wiichuck->process(wiichuck) < 0)
+                       goto disconnect;
+
+               /* Setup the next transfer */
+               if (wiichuck_setaddr(wiichuck, 0) < 0)
+                       goto disconnect;
+               break;
+
+       default:
+               goto disconnect;
+       }
+       return;
+
+ disconnect:
+       dev_info(&wiichuck->i2c_client->dev, "disconnected\n");
+       wiichuck->state = WIICHUCK_STATE_DISCONNECTED;
+       poll_dev->poll_interval = WIICHUCK_POLL_PERIOD;
+}
+
+/**
+ * wiichuck_open() - Set up initial state machine state
+ *
+ * Called exactly once the first time the device is opened by
+ * userspace.  Will not be called again unless all users close it
+ * before reopening.  This simply clears the state to disconnected and
+ * sets the poll rate back to the slow speed
+ */
+static void wiichuck_open(struct input_polled_dev *poll_dev)
+{
+       struct wiichuck_device *wiichuck = poll_dev->private;
+
+       wiichuck->process = wiichuck_process_unknown;
+       wiichuck->state = WIICHUCK_STATE_DISCONNECTED;
+       wiichuck->poll_dev->poll_interval = WIICHUCK_POLL_PERIOD;
+}
+
+static int __devinit wiichuck_probe(struct i2c_client *client,
+                               const struct i2c_device_id *id)
+{
+       struct wiichuck_device *wiichuck;
+       struct input_polled_dev *poll_dev;
+       struct input_dev *input_dev;
+       int rc;
+
+       wiichuck = kzalloc(sizeof(*wiichuck), GFP_KERNEL);
+       if (!wiichuck)
+               return -ENOMEM;
+
+       poll_dev = input_allocate_polled_device();
+       if (!poll_dev) {
+               rc = -ENOMEM;
+               goto err_alloc;
+       }
+
+       wiichuck->i2c_client = client;
+       wiichuck->poll_dev = poll_dev;
+
+       poll_dev->private = wiichuck;
+       poll_dev->poll = wiichuck_poll;
+       poll_dev->open = wiichuck_open;
+
+       input_dev = poll_dev->input;
+       input_dev->name = "Wiichuck expansion connector";
+       input_dev->id.bustype = BUS_I2C;
+       input_dev->dev.parent = &client->dev;
+
+       /* Declare the events generated by this driver */
+       __set_bit(EV_ABS, input_dev->evbit);
+       __set_bit(EV_KEY, input_dev->evbit);
+
+       /* Nunchuck ranges */
+       __set_bit(ABS_X, input_dev->absbit); /* joystick */
+       __set_bit(ABS_Y, input_dev->absbit);
+       input_set_abs_params(input_dev, ABS_X, 30, 220, 4, 8);
+       input_set_abs_params(input_dev, ABS_Y, 40, 200, 4, 8);
+
+       __set_bit(ABS_RX, input_dev->absbit); /* accelerometer */
+       __set_bit(ABS_RY, input_dev->absbit);
+       __set_bit(ABS_RZ, input_dev->absbit);
+       input_set_abs_params(input_dev, ABS_RX, 0, 0x3ff, 4, 8);
+       input_set_abs_params(input_dev, ABS_RY, 0, 0x3ff, 4, 8);
+       input_set_abs_params(input_dev, ABS_RZ, 0, 0x3ff, 4, 8);
+
+       /* Nunchuck buttons */
+       __set_bit(BTN_C, input_dev->keybit);
+       __set_bit(BTN_Z, input_dev->keybit);
+
+       /* Classic ranges */
+       __set_bit(ABS_HAT0X, input_dev->absbit); /* Left Joystick */
+       __set_bit(ABS_HAT0Y, input_dev->absbit);
+       input_set_abs_params(input_dev, ABS_HAT0X, 0, 63, 2, 4);
+       input_set_abs_params(input_dev, ABS_HAT0Y, 0, 63, 2, 4);
+
+       __set_bit(ABS_HAT1X, input_dev->absbit); /* Right Joystick */
+       __set_bit(ABS_HAT1Y, input_dev->absbit);
+       input_set_abs_params(input_dev, ABS_HAT1X, 0, 31, 1, 2);
+       input_set_abs_params(input_dev, ABS_HAT1Y, 0, 31, 1, 2);
+
+       __set_bit(ABS_HAT2X, input_dev->absbit); /* D-pad */
+       __set_bit(ABS_HAT2Y, input_dev->absbit);
+       input_set_abs_params(input_dev, ABS_HAT2X, -1, 1, 0, 0);
+       input_set_abs_params(input_dev, ABS_HAT2Y, -1, 1, 0, 0);
+
+       __set_bit(ABS_BRAKE, input_dev->absbit); /* Left trigger */
+       input_set_abs_params(input_dev, ABS_BRAKE, 0, 31, 1, 2);
+       __set_bit(ABS_GAS, input_dev->absbit);
+       input_set_abs_params(input_dev, ABS_GAS, 0, 31, 1, 2);
+
+       /* Classic buttons */
+       __set_bit(BTN_TL, input_dev->keybit);
+       __set_bit(BTN_SELECT, input_dev->keybit);
+       __set_bit(BTN_MODE, input_dev->keybit);
+       __set_bit(BTN_START, input_dev->keybit);
+       __set_bit(BTN_TR, input_dev->keybit);
+       __set_bit(BTN_TL2, input_dev->keybit);
+       __set_bit(BTN_B, input_dev->keybit);
+       __set_bit(BTN_Y, input_dev->keybit);
+       __set_bit(BTN_A, input_dev->keybit);
+       __set_bit(BTN_X, input_dev->keybit);
+       __set_bit(BTN_TR2, input_dev->keybit);
+
+       i2c_set_clientdata(client, wiichuck);
+
+       /* Register the device; it is 'live' after this point */
+       rc = input_register_polled_device(wiichuck->poll_dev);
+       if (rc) {
+               dev_err(&client->dev, "Failed to register input device\n");
+               goto err_register;
+       }
+
+       return 0;
+
+ err_register:
+       i2c_set_clientdata(client, NULL);
+       input_free_polled_device(poll_dev);
+ err_alloc:
+       kfree(wiichuck);
+
+       return rc;
+}
+
+static int __devexit wiichuck_remove(struct i2c_client *client)
+{
+       struct wiichuck_device *wiichuck = i2c_get_clientdata(client);
+
+       i2c_set_clientdata(client, NULL);
+       input_unregister_polled_device(wiichuck->poll_dev);
+       input_free_polled_device(wiichuck->poll_dev);
+       kfree(wiichuck);
+
+       return 0;
+}
+
+static const struct i2c_device_id wiichuck_id[] = {
+       { "wiichuck", 0 },
+       { }
+};
+MODULE_DEVICE_TABLE(i2c, wiichuck_id);
+
+#ifdef CONFIG_OF
+static struct of_device_id wiichuck_match_table[] __devinitdata = {
+       { .compatible = "nintendo,wiimote-extension", },
+       { }
+};
+#else
+#define wiichuck_match_table NULL
+#endif
+
+static struct i2c_driver wiichuck_driver = {
+       .driver = {
+               .name = "wiichuck",
+               .owner = THIS_MODULE,
+               .of_match_table = wiichuck_match_table,
+       },
+       .probe          = wiichuck_probe,
+       .remove         = __devexit_p(wiichuck_remove),
+       .id_table       = wiichuck_id,
+};
+
+static int __init wiichuck_init(void)
+{
+       return i2c_add_driver(&wiichuck_driver);
+}
+module_init(wiichuck_init);
+
+static void __exit wiichuck_exit(void)
+{
+       i2c_del_driver(&wiichuck_driver);
+}
+module_exit(wiichuck_exit);