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    SubjectRe: [RFC PATCH] input: Add wiichuck driver
    Hi Grant,

    On Thu, May 12, 2011 at 06:29:44AM +0200, Grant Likely wrote:
    > This patch adds a driver for the Nintendo Nunchuck (wiimote accessory)
    > attached to an i2c bus via something like a wiichuck adapter board
    > from Sparkfun.
    >
    > Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
    > ---
    >
    > This is RFC because the driver doesn't completely work yet. The
    > joystick and buttons work fine. There is a bug with the accelerometer
    > reporting though (nothing gets reported), and I'm not even sure I'm
    > using the right input type for reporting accelerometer values.

    Looks quite reasonable and I think that ABS_Rx is reasonable events for
    accelerometer in this particular case.

    A few more comments below.

    > Comments welcome.
    >
    > drivers/input/joystick/Kconfig | 8 +
    > drivers/input/joystick/Makefile | 1
    > drivers/input/joystick/wiichuck.c | 225 +++++++++++++++++++++++++++++++++++++
    > 3 files changed, 234 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..79f18db 100644
    > --- a/drivers/input/joystick/Kconfig
    > +++ b/drivers/input/joystick/Kconfig
    > @@ -193,6 +193,14 @@ config JOYSTICK_TWIDJOY
    > To compile this driver as a module, choose M here: the
    > module will be called twidjoy.
    >
    > +config JOYSTICK_WIICHUCK
    > + tristate "Nintendo Nunchuck on i2c bus"
    > + depends on I2C
    > + select INPUT_POLLDEV
    > + help
    > + Say Y here if you have a Nintendo Nunchuck directly attached to
    > + the machine's i2c bus.
    > +

    To compile this driver as a module, ...

    > 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..2afc274
    > --- /dev/null
    > +++ b/drivers/input/joystick/wiichuck.c
    > @@ -0,0 +1,225 @@
    > +/*
    > + * Nintendo Nunchuck driver for i2c connection.
    > + *
    > + * Copyright (c) 2011 Secret Lab Technologies Ltd.
    > + *
    > + * This program is free software; you can redistribute it and/or modify
    > + * it under the terms of the GNU General Public License as published by
    > + * the Free Software Foundation; either version 2 of the License, or
    > + * (at your option) any later version.
    > + *
    > + * This program is distributed in the hope that it will be useful,
    > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
    > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    > + * GNU General Public License for more details.
    > + *
    > + * You should have received a copy of the GNU General Public License
    > + * along with this program; if not, write to the Free Software
    > + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
    > + *
    > + */
    > +
    > +#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("Nintendo Nunchuck driver");
    > +MODULE_LICENSE("GPL");
    > +
    > +#define WIICHUCK_JOY_MAX_AXIS 220
    > +#define WIICHUCK_JOY_MIN_AXIS 30
    > +#define WIICHUCK_JOY_FUZZ 4
    > +#define WIICHUCK_JOY_FLAT 8
    > +
    > +struct wiichuck_device {
    > + struct input_polled_dev *poll_dev;
    > + struct i2c_client *i2c_client;
    > + int state;
    > +};
    > +
    > +static void wiichuck_poll(struct input_polled_dev *poll_dev)
    > +{
    > + struct wiichuck_device *wiichuck = poll_dev->private;
    > + struct i2c_client *i2c = wiichuck->i2c_client;
    > + static uint8_t cmd_byte = 0;
    > + struct i2c_msg cmd_msg =
    > + { .addr = i2c->addr, .len = 1, .buf = &cmd_byte };
    > + uint8_t b[6];

    As mentioned by others these buffers should not be on stack.

    > + struct i2c_msg data_msg =
    > + { .addr = i2c->addr, .flags = I2C_M_RD, .len = 6, .buf = b };
    > + int jx, jy, ax, ay, az;
    > + bool c, z;
    > +
    > + switch (wiichuck->state) {
    > + case 0:
    > + i2c_transfer(i2c->adapter, &cmd_msg, 1);
    > + wiichuck->state = 1;

    Do you really need to have a state machine here? Why not do both
    transfers in one poll invocation?

    > + break;
    > +
    > + case 1:
    > + i2c_transfer(i2c->adapter, &data_msg, 1);
    > +
    > + jx = b[0];
    > + jy = b[1];
    > + ax = (b[2] << 2) & ((b[5] >> 2) & 0x3);
    > + ay = (b[3] << 2) & ((b[5] >> 4) & 0x3);
    > + az = (b[4] << 2) & ((b[5] >> 6) & 0x3);
    > + z = !(b[5] & 1);
    > + c = !(b[5] & 2);
    > +
    > + input_report_abs(poll_dev->input, ABS_X, jx);
    > + input_report_abs(poll_dev->input, ABS_Y, jy);
    > + input_report_abs(poll_dev->input, ABS_RX, ax);
    > + input_report_abs(poll_dev->input, ABS_RY, ax);
    > + input_report_abs(poll_dev->input, ABS_RZ, ay);
    > + input_report_key(poll_dev->input, BTN_C, c);
    > + input_report_key(poll_dev->input, BTN_Z, z);
    > + input_sync(poll_dev->input);
    > +
    > + wiichuck->state = 0;
    > + dev_dbg(&i2c->dev, "wiichuck: j=%.3i,%.3i a=%.3x,%.3x,%.3x %c%c\n",
    > + jx,jy, ax,ay,az, c ? 'C' : 'c', z ? 'Z' : 'z');
    > + break;
    > +
    > + default:
    > + wiichuck->state = 0;
    > + }
    > +}
    > +
    > +static void wiichuck_open(struct input_polled_dev *poll_dev)
    > +{
    > + struct wiichuck_device *wiichuck = poll_dev->private;
    > + struct i2c_client *i2c = wiichuck->i2c_client;
    > + static uint8_t data1[2] = { 0xf0, 0x55 };
    > + static uint8_t data2[2] = { 0xfb, 0x00 };
    > + struct i2c_msg msg1 = { .addr = i2c->addr, .len = 2, .buf = data1 };
    > + struct i2c_msg msg2 = { .addr = i2c->addr, .len = 2, .buf = data2 };
    > +
    > + i2c_transfer(i2c->adapter, &msg1, 1);
    > + i2c_transfer(i2c->adapter, &msg2, 1);
    > + wiichuck->state = 0;
    > +
    > + dev_dbg(&i2c->dev, "wiichuck open()\n");
    > +}
    > +
    > +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->poll_interval = 50; /* Poll every 50ms */
    > + poll_dev->open = wiichuck_open;
    > +
    > + input_dev = poll_dev->input;
    > + input_dev->name = "Nintendo Nunchuck";
    > + 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(ABS_X, input_dev->absbit); /* joystick */
    > + set_bit(ABS_Y, input_dev->absbit);
    > + set_bit(ABS_RX, input_dev->absbit); /* accelerometer */
    > + set_bit(ABS_RY, input_dev->absbit);
    > + set_bit(ABS_RZ, input_dev->absbit);
    > +
    > + set_bit(EV_KEY, input_dev->evbit);
    > + set_bit(BTN_C, input_dev->keybit); /* buttons */
    > + set_bit(BTN_Z, input_dev->keybit);

    I prefer __set_bit() here since there is no concurrency.

    > +
    > + input_set_abs_params(input_dev, ABS_X, 30, 220, 4, 8);
    > + input_set_abs_params(input_dev, ABS_Y, 40, 200, 4, 8);
    > + 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);
    > +
    > + rc = input_register_polled_device(wiichuck->poll_dev);
    > + if (rc) {
    > + dev_err(&client->dev, "Failed to register input device\n");
    > + goto err_register;
    > + }
    > +
    > + i2c_set_clientdata(client, wiichuck);
    > +
    > + return 0;
    > +
    > + err_register:
    > + 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[] = {
    > + { "nunchuck", 0 },
    > + { }
    > +};
    > +MODULE_DEVICE_TABLE(i2c, wiichuck_id);
    > +
    > +#ifdef CONFIG_OF
    > +static struct of_device_id wiichuck_match_table[] __devinitdata = {
    > + { .compatible = "nintendo,nunchuck", },
    > + { }
    > +};
    > +#else
    > +#define wiichuck_match_table NULL
    > +#endif
    > +
    > +static struct i2c_driver wiichuck_driver = {
    > + .driver = {
    > + .name = "nunchuck",
    > + .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);
    >

    Thanks.

    --
    Dmitry


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