drivers/media/radio/radio-keene.c

Source file repositories/reference/linux-study-clean/drivers/media/radio/radio-keene.c

File Facts

System
Linux kernel
Corpus path
drivers/media/radio/radio-keene.c
Extension
.c
Size
11369 bytes
Lines
406
Domain
Driver Families
Bucket
drivers/media
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct keene_device {
	struct usb_device *usbdev;
	struct usb_interface *intf;
	struct video_device vdev;
	struct v4l2_device v4l2_dev;
	struct v4l2_ctrl_handler hdl;
	struct mutex lock;

	u8 *buffer;
	unsigned curfreq;
	u8 tx;
	u8 pa;
	bool stereo;
	bool muted;
	bool preemph_75_us;
};

static inline struct keene_device *to_keene_dev(struct v4l2_device *v4l2_dev)
{
	return container_of(v4l2_dev, struct keene_device, v4l2_dev);
}

/* Set frequency (if non-0), PA, mute and turn on/off the FM transmitter. */
static int keene_cmd_main(struct keene_device *radio, unsigned freq, bool play)
{
	unsigned short freq_send = freq ? (freq - 76 * 16000) / 800 : 0;
	int ret;

	radio->buffer[0] = 0x00;
	radio->buffer[1] = 0x50;
	radio->buffer[2] = (freq_send >> 8) & 0xff;
	radio->buffer[3] = freq_send & 0xff;
	radio->buffer[4] = radio->pa;
	/* If bit 4 is set, then tune to the frequency.
	   If bit 3 is set, then unmute; if bit 2 is set, then mute.
	   If bit 1 is set, then enter idle mode; if bit 0 is set,
	   then enter transmit mode.
	 */
	radio->buffer[5] = (radio->muted ? 4 : 8) | (play ? 1 : 2) |
							(freq ? 0x10 : 0);
	radio->buffer[6] = 0x00;
	radio->buffer[7] = 0x00;

	ret = usb_control_msg(radio->usbdev, usb_sndctrlpipe(radio->usbdev, 0),
		9, 0x21, 0x200, 2, radio->buffer, BUFFER_LENGTH, USB_TIMEOUT);

	if (ret < 0) {
		dev_warn(&radio->vdev.dev, "%s failed (%d)\n", __func__, ret);
		return ret;
	}
	if (freq)
		radio->curfreq = freq;
	return 0;
}

/* Set TX, stereo and preemphasis mode (50 us vs 75 us). */
static int keene_cmd_set(struct keene_device *radio)
{
	int ret;

	radio->buffer[0] = 0x00;
	radio->buffer[1] = 0x51;
	radio->buffer[2] = radio->tx;
	/* If bit 0 is set, then transmit mono, otherwise stereo.
	   If bit 2 is set, then enable 75 us preemphasis, otherwise
	   it is 50 us. */
	radio->buffer[3] = (radio->stereo ? 0 : 1) | (radio->preemph_75_us ? 4 : 0);
	radio->buffer[4] = 0x00;
	radio->buffer[5] = 0x00;
	radio->buffer[6] = 0x00;
	radio->buffer[7] = 0x00;

	ret = usb_control_msg(radio->usbdev, usb_sndctrlpipe(radio->usbdev, 0),
		9, 0x21, 0x200, 2, radio->buffer, BUFFER_LENGTH, USB_TIMEOUT);

	if (ret < 0) {
		dev_warn(&radio->vdev.dev, "%s failed (%d)\n", __func__, ret);
		return ret;
	}
	return 0;
}

/* Handle unplugging the device.
 * We call video_unregister_device in any case.
 * The last function called in this procedure is
 * usb_keene_device_release.
 */
static void usb_keene_disconnect(struct usb_interface *intf)
{
	struct keene_device *radio = to_keene_dev(usb_get_intfdata(intf));

Annotation

Implementation Notes