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SubjectRe: [PATCH] maple: add driver for Sega Dreamcast controller
On Sat, 16 Feb 2008 23:50:15 +0000 Adrian McMenamin <adrian@newgolddream.dyndns.info> wrote:

> Add support for the SEGA Dreamcast controller as a joystick device. Based on Yaegashi Takeshi's old 2.4 driver (never in mainline) with the addition of functioning removal (and reinsertion) code.
>
> ...
>
> +static void dc_pad_callback(struct mapleq *mq)
> +{
> + unsigned short buttons;
> + struct maple_device *mapledev = mq->dev;
> + struct dc_pad *pad = mapledev->private_data;
> + struct input_dev *dev = pad->dev;
> + unsigned char *res = mq->recvbuf;
> +
> + buttons = ~*(unsigned short *)(res+8);

This is endianness-dependent. Presumably it "works", but it's pretty poor
practice.

> ...
>
>> +static int dc_pad_connect(struct maple_device *mdev)
> +{
> + int i, error;
> + unsigned long data = be32_to_cpu(mdev->devinfo.function_data[0]);
> + struct dc_pad *pad;
> + struct input_dev *dev;
> +
> + const short btn_bit[32] = {
> + BTN_C, BTN_B, BTN_A, BTN_START, -1, -1, -1, -1,
> + BTN_Z, BTN_Y, BTN_X, BTN_SELECT, -1, -1, -1, -1,
> + -1, -1, -1, -1, -1, -1, -1, -1,
> + -1, -1, -1, -1, -1, -1, -1, -1,
> + };
> +
> + const short abs_bit[32] = {
> + -1, -1, -1, -1, ABS_HAT0Y, ABS_HAT0Y, ABS_HAT0X, ABS_HAT0X,
> + -1, -1, -1, -1, ABS_HAT1Y, ABS_HAT1Y, ABS_HAT1X, ABS_HAT1X,
> + ABS_GAS, ABS_BRAKE, ABS_X, ABS_Y, ABS_RX, ABS_RY, -1, -1,
> + -1, -1, -1, -1, -1, -1, -1, -1,
> + };
> +
> + pad = kzalloc(sizeof(struct dc_pad), GFP_KERNEL);
> + if (!pad)
> + return -ENOMEM;
> +
> + dev = input_allocate_device();
> + if (!dev) {
> + kfree(pad);
> + return -ENOMEM;
> + }
> +
> + pad->dev = dev;
> + pad->mdev = mdev;
> + mdev->private_data = pad;
> +
> + for (i = 0; i < 32; i++)
> + if (data & (1<<i) && btn_bit[i] >= 0)
> + pad->dev->keybit[BTN_JOYSTICK/32] |= BIT(btn_bit[i]);
> +
> + if (pad->dev->keybit[BTN_JOYSTICK/32])
> + pad->dev->evbit[0] |= BIT(EV_KEY);
> +
> + for (i = 0; i < 32; i++)
> + if (data & (1<<i) && abs_bit[i] >= 0)
> + pad->dev->absbit[0] |= BIT(abs_bit[i]);
> +
> + if (pad->dev->absbit[0])
> + pad->dev->evbit[0] |= BIT(EV_ABS);
> +
> + for (i = ABS_X; i <= ABS_BRAKE; i++) {
> + pad->dev->absmax[i] = 255;
> + pad->dev->absmin[i] = 0;
> + pad->dev->absfuzz[i] = 0;
> + pad->dev->absflat[i] = 0;
> + }
> +
> + for (i = ABS_HAT0X; i <= ABS_HAT3Y; i++) {
> + pad->dev->absmax[i] = 1;
> + pad->dev->absmin[i] = -1;
> + pad->dev->absfuzz[i] = 0;
> + pad->dev->absflat[i] = 0;
> + }
> +
> + pad->dev->open = dc_pad_open;
> + pad->dev->close = dc_pad_close;
> + pad->dev->private = pad;
> + pad->dev->event = NULL;
> + pad->dev->dev.parent = &mdev->dev;
> + pad->dev->name = mdev->product_name;
> + pad->dev->id.bustype = BUS_HOST;
> + input_set_drvdata(dev, pad);
> +
> + error = input_register_device(pad->dev);
> + if (error) {
> + input_free_device(pad->dev);
> + kfree(pad);
> + return -error;
> + }
> +
> + maple_getcond_callback(mdev, dc_pad_callback_idle, 0xFFFFFFFF,
> + MAPLE_FUNC_CONTROLLER);
> +
> + return 0;
> +}

The error handling in here would be more maintainable if it were to use the
usual `goto err_foo' approach - aim for only a single return statement per
function.



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