V4L/DVB (12142): radio-si470x: Add suport for RDS endpoint interrupt mode

Add support for interrupt mode for RDS endpoint, instead of polling.
Improves RDS reception significantly

Signed-off-by: Edouard Lafargue <edouard@lafargue.name>
Acked-by: Tobias Lorenz <tobias.lorenz@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/radio/radio-si470x.c

@@ -106,20 +106,24 @@
  *		Tobias Lorenz <tobias.lorenz@gmx.net>
  *		- add LED status output
  *		- get HW/SW version from scratchpad
+ * 2009-06-16   Edouard Lafargue <edouard@lafargue.name>
+ *		Version 1.0.10
+ *		- add support for interrupt mode for RDS endpoint,
+ *                instead of polling.
+ *                Improves RDS reception significantly
  *
  * ToDo:
  * - add firmware download/update support
- * - RDS support: interrupt mode, instead of polling
  */
 
 
 /* driver definitions */
 #define DRIVER_AUTHOR "Tobias Lorenz <tobias.lorenz@gmx.net>"
 #define DRIVER_NAME "radio-si470x"
-#define DRIVER_KERNEL_VERSION KERNEL_VERSION(1, 0, 9)
+#define DRIVER_KERNEL_VERSION KERNEL_VERSION(1, 0, 10)
 #define DRIVER_CARD "Silicon Labs Si470x FM Radio Receiver"
 #define DRIVER_DESC "USB radio driver for Si470x FM Radio Receivers"
-#define DRIVER_VERSION "1.0.9"
+#define DRIVER_VERSION "1.0.10"
 
 
 /* kernel includes */
@@ -218,16 +222,6 @@ static unsigned short max_rds_errors = 1;
 module_param(max_rds_errors, ushort, 0644);
 MODULE_PARM_DESC(max_rds_errors, "RDS maximum block errors: *1*");
 
-/* RDS poll frequency */
-static unsigned int rds_poll_time = 40;
-/* 40 is used by the original USBRadio.exe */
-/* 50 is used by radio-cadet */
-/* 75 should be okay */
-/* 80 is the usual RDS receive interval */
-module_param(rds_poll_time, uint, 0644);
-MODULE_PARM_DESC(rds_poll_time, "RDS poll time (ms): *40*");
-
-
 
 /**************************************************************************
  * Register Definitions
@@ -450,6 +444,12 @@ struct si470x_device {
 	struct usb_interface *intf;
 	struct video_device *videodev;
 
+	/* Interrupt endpoint handling */
+	char *int_in_buffer;
+	struct usb_endpoint_descriptor *int_in_endpoint;
+	struct urb *int_in_urb;
+	int int_in_running;
+
 	/* driver management */
 	unsigned int users;
 	unsigned char disconnected;
@@ -459,7 +459,6 @@ struct si470x_device {
 	unsigned short registers[RADIO_REGISTER_NUM];
 
 	/* RDS receive buffer */
-	struct delayed_work work;
 	wait_queue_head_t read_queue;
 	struct mutex lock;		/* buffer locking */
 	unsigned char *buffer;		/* size is always multiple of three */
@@ -864,43 +863,6 @@ static int si470x_get_all_registers(struct si470x_device *radio)
 
 
 
-/**************************************************************************
- * General Driver Functions - RDS_REPORT
- **************************************************************************/
-
-/*
- * si470x_get_rds_registers - read rds registers
- */
-static int si470x_get_rds_registers(struct si470x_device *radio)
-{
-	unsigned char buf[RDS_REPORT_SIZE];
-	int retval;
-	int size;
-	unsigned char regnr;
-
-	buf[0] = RDS_REPORT;
-
-	retval = usb_interrupt_msg(radio->usbdev,
-		usb_rcvintpipe(radio->usbdev, 1),
-		(void *) &buf, sizeof(buf), &size, usb_timeout);
-	if (size != sizeof(buf))
-		printk(KERN_WARNING DRIVER_NAME ": si470x_get_rds_registers: "
-			"return size differs: %d != %zu\n", size, sizeof(buf));
-	if (retval < 0)
-		printk(KERN_WARNING DRIVER_NAME ": si470x_get_rds_registers: "
-			"usb_interrupt_msg returned %d\n", retval);
-
-	if (retval >= 0)
-		for (regnr = 0; regnr < RDS_REGISTER_NUM; regnr++)
-			radio->registers[STATUSRSSI + regnr] =
-				get_unaligned_be16(
-				&buf[regnr * RADIO_REGISTER_SIZE + 1]);
-
-	return (retval < 0) ? -EINVAL : 0;
-}
-
-
-
 /**************************************************************************
  * General Driver Functions - LED_REPORT
  **************************************************************************/
@@ -959,102 +921,118 @@ static int si470x_get_scratch_page_versions(struct si470x_device *radio)
  **************************************************************************/
 
 /*
- * si470x_rds - rds processing function
+ * si470x_int_in_callback - rds callback and processing function
+ *
+ * TODO: do we need to use mutex locks in some sections?
  */
-static void si470x_rds(struct si470x_device *radio)
+static void si470x_int_in_callback(struct urb *urb)
 {
+	struct si470x_device *radio = urb->context;
+	unsigned char buf[RDS_REPORT_SIZE];
+	int retval;
+	unsigned char regnr;
 	unsigned char blocknum;
 	unsigned short bler; /* rds block errors */
 	unsigned short rds;
 	unsigned char tmpbuf[3];
 
-	/* get rds blocks */
-	if (si470x_get_rds_registers(radio) < 0)
-		return;
-	if ((radio->registers[STATUSRSSI] & STATUSRSSI_RDSR) == 0) {
-		/* No RDS group ready */
-		return;
-	}
-	if ((radio->registers[STATUSRSSI] & STATUSRSSI_RDSS) == 0) {
-		/* RDS decoder not synchronized */
-		return;
-	}
-
-	/* copy all four RDS blocks to internal buffer */
-	mutex_lock(&radio->lock);
-	for (blocknum = 0; blocknum < 4; blocknum++) {
-		switch (blocknum) {
-		default:
-			bler = (radio->registers[STATUSRSSI] &
-					STATUSRSSI_BLERA) >> 9;
-			rds = radio->registers[RDSA];
-			break;
-		case 1:
-			bler = (radio->registers[READCHAN] &
-					READCHAN_BLERB) >> 14;
-			rds = radio->registers[RDSB];
-			break;
-		case 2:
-			bler = (radio->registers[READCHAN] &
-					READCHAN_BLERC) >> 12;
-			rds = radio->registers[RDSC];
-			break;
-		case 3:
-			bler = (radio->registers[READCHAN] &
-					READCHAN_BLERD) >> 10;
-			rds = radio->registers[RDSD];
-			break;
-		};
-
-		/* Fill the V4L2 RDS buffer */
-		put_unaligned_le16(rds, &tmpbuf);
-		tmpbuf[2] = blocknum;		/* offset name */
-		tmpbuf[2] |= blocknum << 3;	/* received offset */
-		if (bler > max_rds_errors)
-			tmpbuf[2] |= 0x80; /* uncorrectable errors */
-		else if (bler > 0)
-			tmpbuf[2] |= 0x40; /* corrected error(s) */
-
-		/* copy RDS block to internal buffer */
-		memcpy(&radio->buffer[radio->wr_index], &tmpbuf, 3);
-		radio->wr_index += 3;
-
-		/* wrap write pointer */
-		if (radio->wr_index >= radio->buf_size)
-			radio->wr_index = 0;
-
-		/* check for overflow */
-		if (radio->wr_index == radio->rd_index) {
-			/* increment and wrap read pointer */
-			radio->rd_index += 3;
-			if (radio->rd_index >= radio->buf_size)
-				radio->rd_index = 0;
+	if (urb->status) {
+		if (urb->status == -ENOENT ||
+				urb->status == -ECONNRESET ||
+				urb->status == -ESHUTDOWN) {
+			return;
+		} else {
+			printk(KERN_WARNING DRIVER_NAME
+			 ": non-zero urb status (%d)\n", urb->status);
+			goto resubmit; /* Maybe we can recover. */
 		}
 	}
-	mutex_unlock(&radio->lock);
-
-	/* wake up read queue */
-	if (radio->wr_index != radio->rd_index)
-		wake_up_interruptible(&radio->read_queue);
-}
-
-
-/*
- * si470x_work - rds work function
- */
-static void si470x_work(struct work_struct *work)
-{
-	struct si470x_device *radio = container_of(work, struct si470x_device,
-		work.work);
 
 	/* safety checks */
 	if (radio->disconnected)
 		return;
 	if ((radio->registers[SYSCONFIG1] & SYSCONFIG1_RDS) == 0)
-		return;
+		goto resubmit;
 
-	si470x_rds(radio);
-	schedule_delayed_work(&radio->work, msecs_to_jiffies(rds_poll_time));
+	if (urb->actual_length > 0) {
+		/* Update RDS registers with URB data */
+		buf[0] = RDS_REPORT;
+		for (regnr = 0; regnr < RDS_REGISTER_NUM; regnr++)
+			radio->registers[STATUSRSSI + regnr] =
+			    get_unaligned_be16(&radio->int_in_buffer[
+				regnr * RADIO_REGISTER_SIZE + 1]);
+		/* get rds blocks */
+		if ((radio->registers[STATUSRSSI] & STATUSRSSI_RDSR) == 0) {
+			/* No RDS group ready, better luck next time */
+			goto resubmit;
+		}
+		if ((radio->registers[STATUSRSSI] & STATUSRSSI_RDSS) == 0) {
+			/* RDS decoder not synchronized */
+			goto resubmit;
+		}
+		for (blocknum = 0; blocknum < 4; blocknum++) {
+			switch (blocknum) {
+			default:
+				bler = (radio->registers[STATUSRSSI] &
+						STATUSRSSI_BLERA) >> 9;
+				rds = radio->registers[RDSA];
+				break;
+			case 1:
+				bler = (radio->registers[READCHAN] &
+						READCHAN_BLERB) >> 14;
+				rds = radio->registers[RDSB];
+				break;
+			case 2:
+				bler = (radio->registers[READCHAN] &
+						READCHAN_BLERC) >> 12;
+				rds = radio->registers[RDSC];
+				break;
+			case 3:
+				bler = (radio->registers[READCHAN] &
+						READCHAN_BLERD) >> 10;
+				rds = radio->registers[RDSD];
+				break;
+			};
+
+			/* Fill the V4L2 RDS buffer */
+			put_unaligned_le16(rds, &tmpbuf);
+			tmpbuf[2] = blocknum;		/* offset name */
+			tmpbuf[2] |= blocknum << 3;	/* received offset */
+			if (bler > max_rds_errors)
+				tmpbuf[2] |= 0x80; /* uncorrectable errors */
+			else if (bler > 0)
+				tmpbuf[2] |= 0x40; /* corrected error(s) */
+
+			/* copy RDS block to internal buffer */
+			memcpy(&radio->buffer[radio->wr_index], &tmpbuf, 3);
+			radio->wr_index += 3;
+
+			/* wrap write pointer */
+			if (radio->wr_index >= radio->buf_size)
+				radio->wr_index = 0;
+
+			/* check for overflow */
+			if (radio->wr_index == radio->rd_index) {
+				/* increment and wrap read pointer */
+				radio->rd_index += 3;
+				if (radio->rd_index >= radio->buf_size)
+					radio->rd_index = 0;
+			}
+		}
+		if (radio->wr_index != radio->rd_index)
+			wake_up_interruptible(&radio->read_queue);
+	}
+
+resubmit:
+	/* Resubmit if we're still running. */
+	if (radio->int_in_running && radio->usbdev) {
+		retval = usb_submit_urb(radio->int_in_urb, GFP_ATOMIC);
+		if (retval) {
+			printk(KERN_WARNING DRIVER_NAME
+			       ": resubmitting urb failed (%d)", retval);
+			radio->int_in_running = 0;
+		}
+	}
 }
 
 
@@ -1076,8 +1054,6 @@ static ssize_t si470x_fops_read(struct file *file, char __user *buf,
 	/* switch on rds reception */
 	if ((radio->registers[SYSCONFIG1] & SYSCONFIG1_RDS) == 0) {
 		si470x_rds_on(radio);
-		schedule_delayed_work(&radio->work,
-			msecs_to_jiffies(rds_poll_time));
 	}
 
 	/* block if no new data available */
@@ -1136,8 +1112,6 @@ static unsigned int si470x_fops_poll(struct file *file,
 	/* switch on rds reception */
 	if ((radio->registers[SYSCONFIG1] & SYSCONFIG1_RDS) == 0) {
 		si470x_rds_on(radio);
-		schedule_delayed_work(&radio->work,
-			msecs_to_jiffies(rds_poll_time));
 	}
 
 	poll_wait(file, &radio->read_queue, pts);
@@ -1167,11 +1141,37 @@ static int si470x_fops_open(struct file *file)
 		goto done;
 	}
 
+	printk(KERN_INFO DRIVER_NAME
+		 ": Opened radio (users now: %i)\n", radio->users);
+
 	if (radio->users == 1) {
 		/* start radio */
 		retval = si470x_start(radio);
-		if (retval < 0)
+		if (retval < 0) {
 			usb_autopm_put_interface(radio->intf);
+			goto done;
+		}
+		/* Initialize interrupt URB. */
+		usb_fill_int_urb(radio->int_in_urb, radio->usbdev,
+			usb_rcvintpipe(radio->usbdev,
+			radio->int_in_endpoint->bEndpointAddress),
+			radio->int_in_buffer,
+			le16_to_cpu(radio->int_in_endpoint->wMaxPacketSize),
+			si470x_int_in_callback,
+			radio,
+			radio->int_in_endpoint->bInterval);
+
+		radio->int_in_running = 1;
+		mb();
+
+		retval = usb_submit_urb(radio->int_in_urb, GFP_KERNEL);
+		if (retval) {
+			printk(KERN_INFO DRIVER_NAME
+				 ": submitting int urb failed (%d)\n", retval);
+			radio->int_in_running = 0;
+			usb_autopm_put_interface(radio->intf);
+		}
+
 	}
 
 done:
@@ -1196,17 +1196,25 @@ static int si470x_fops_release(struct file *file)
 
 	mutex_lock(&radio->disconnect_lock);
 	radio->users--;
+	printk(KERN_INFO DRIVER_NAME
+		 ": Closed radio (remaining users:%i)\n", radio->users);
 	if (radio->users == 0) {
+
+		/* Shutdown Interrupt handler */
+		if (radio->int_in_running) {
+			radio->int_in_running = 0;
+		if (radio->int_in_urb)
+			usb_kill_urb(radio->int_in_urb);
+		}
+
 		if (radio->disconnected) {
 			video_unregister_device(radio->videodev);
+			kfree(radio->int_in_buffer);
 			kfree(radio->buffer);
 			kfree(radio);
 			goto unlock;
 		}
 
-		/* stop rds reception */
-		cancel_delayed_work_sync(&radio->work);
-
 		/* cancel read processes */
 		wake_up_interruptible(&radio->read_queue);
 
@@ -1657,7 +1665,9 @@ static int si470x_usb_driver_probe(struct usb_interface *intf,
 		const struct usb_device_id *id)
 {
 	struct si470x_device *radio;
-	int retval = 0;
+	struct usb_host_interface *iface_desc;
+	struct usb_endpoint_descriptor *endpoint;
+	int i, int_end_size, retval = 0;
 
 	/* private data allocation and initialization */
 	radio = kzalloc(sizeof(struct si470x_device), GFP_KERNEL);
@@ -1672,11 +1682,45 @@ static int si470x_usb_driver_probe(struct usb_interface *intf,
 	mutex_init(&radio->disconnect_lock);
 	mutex_init(&radio->lock);
 
+	iface_desc = intf->cur_altsetting;
+
+	/* Set up interrupt endpoint information. */
+	for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
+		endpoint = &iface_desc->endpoint[i].desc;
+		if (((endpoint->bEndpointAddress & USB_ENDPOINT_DIR_MASK) ==
+		 USB_DIR_IN) && ((endpoint->bmAttributes &
+		 USB_ENDPOINT_XFERTYPE_MASK) == USB_ENDPOINT_XFER_INT))
+			radio->int_in_endpoint = endpoint;
+	}
+	if (!radio->int_in_endpoint) {
+		printk(KERN_INFO DRIVER_NAME
+			": could not find interrupt in endpoint\n");
+		retval = -EIO;
+		goto err_radio;
+	}
+
+	int_end_size = le16_to_cpu(radio->int_in_endpoint->wMaxPacketSize);
+
+	radio->int_in_buffer = kmalloc(int_end_size, GFP_KERNEL);
+	if (!radio->int_in_buffer) {
+		printk(KERN_INFO DRIVER_NAME
+			"could not allocate int_in_buffer");
+		retval = -ENOMEM;
+		goto err_radio;
+	}
+
+	radio->int_in_urb = usb_alloc_urb(0, GFP_KERNEL);
+	if (!radio->int_in_urb) {
+		printk(KERN_INFO DRIVER_NAME "could not allocate int_in_urb");
+		retval = -ENOMEM;
+		goto err_intbuffer;
+	}
+
 	/* video device allocation and initialization */
 	radio->videodev = video_device_alloc();
 	if (!radio->videodev) {
 		retval = -ENOMEM;
-		goto err_radio;
+		goto err_intbuffer;
 	}
 	memcpy(radio->videodev, &si470x_viddev_template,
 			sizeof(si470x_viddev_template));
@@ -1734,9 +1778,6 @@ static int si470x_usb_driver_probe(struct usb_interface *intf,
 	radio->rd_index = 0;
 	init_waitqueue_head(&radio->read_queue);
 
-	/* prepare rds work function */
-	INIT_DELAYED_WORK(&radio->work, si470x_work);
-
 	/* register video device */
 	retval = video_register_device(radio->videodev, VFL_TYPE_RADIO, radio_nr);
 	if (retval) {
@@ -1751,6 +1792,8 @@ err_all:
 	kfree(radio->buffer);
 err_video:
 	video_device_release(radio->videodev);
+err_intbuffer:
+	kfree(radio->int_in_buffer);
 err_radio:
 	kfree(radio);
 err_initial:
@@ -1764,12 +1807,8 @@ err_initial:
 static int si470x_usb_driver_suspend(struct usb_interface *intf,
 		pm_message_t message)
 {
-	struct si470x_device *radio = usb_get_intfdata(intf);
-
 	printk(KERN_INFO DRIVER_NAME ": suspending now...\n");
 
-	cancel_delayed_work_sync(&radio->work);
-
 	return 0;
 }
 
@@ -1779,16 +1818,8 @@ static int si470x_usb_driver_suspend(struct usb_interface *intf,
  */
 static int si470x_usb_driver_resume(struct usb_interface *intf)
 {
-	struct si470x_device *radio = usb_get_intfdata(intf);
-
 	printk(KERN_INFO DRIVER_NAME ": resuming now...\n");
 
-	mutex_lock(&radio->lock);
-	if (radio->users && radio->registers[SYSCONFIG1] & SYSCONFIG1_RDS)
-		schedule_delayed_work(&radio->work,
-			msecs_to_jiffies(rds_poll_time));
-	mutex_unlock(&radio->lock);
-
 	return 0;
 }
 
@@ -1802,12 +1833,15 @@ static void si470x_usb_driver_disconnect(struct usb_interface *intf)
 
 	mutex_lock(&radio->disconnect_lock);
 	radio->disconnected = 1;
-	cancel_delayed_work_sync(&radio->work);
 	usb_set_intfdata(intf, NULL);
 	if (radio->users == 0) {
 		/* set led to disconnect state */
 		si470x_set_led_state(radio, BLINK_ORANGE_LED);
 
+		/* Free data structures. */
+		usb_free_urb(radio->int_in_urb);
+
+		kfree(radio->int_in_buffer);
 		video_unregister_device(radio->videodev);
 		kfree(radio->buffer);
 		kfree(radio);