USB: oti6858: use kfifo to implement write buffering

Kill custom fifo implementation.

Use private write fifo to minimise changes to lock handling.

Compile-only tested.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/oti6858.c

@@ -51,12 +51,13 @@
 #include <linux/usb.h>
 #include <linux/usb/serial.h>
 #include <linux/uaccess.h>
+#include <linux/kfifo.h>
 #include "oti6858.h"
 
 #define OTI6858_DESCRIPTION \
 	"Ours Technology Inc. OTi-6858 USB to serial adapter driver"
 #define OTI6858_AUTHOR "Tomasz Michal Lukaszewski <FIXME@FIXME>"
-#define OTI6858_VERSION "0.1"
+#define OTI6858_VERSION "0.2"
 
 static const struct usb_device_id id_table[] = {
 	{ USB_DEVICE(OTI6858_VENDOR_ID, OTI6858_PRODUCT_ID) },
@@ -75,17 +76,7 @@ static struct usb_driver oti6858_driver = {
 
 static int debug;
 
-
-/* buffering code, copied from pl2303 driver */
-#define PL2303_BUF_SIZE		1024
-#define PL2303_TMP_BUF_SIZE	1024
-
-struct oti6858_buf {
-	unsigned int	buf_size;
-	char		*buf_buf;
-	char		*buf_get;
-	char		*buf_put;
-};
+#define OTI6858_FIFO_SIZE		1024
 
 /* requests */
 #define	OTI6858_REQ_GET_STATUS		(USB_DIR_IN | USB_TYPE_VENDOR | 0x00)
@@ -161,18 +152,6 @@ static int oti6858_tiocmset(struct tty_struct *tty, struct file *file,
 static int oti6858_startup(struct usb_serial *serial);
 static void oti6858_release(struct usb_serial *serial);
 
-/* functions operating on buffers */
-static struct oti6858_buf *oti6858_buf_alloc(unsigned int size);
-static void oti6858_buf_free(struct oti6858_buf *pb);
-static void oti6858_buf_clear(struct oti6858_buf *pb);
-static unsigned int oti6858_buf_data_avail(struct oti6858_buf *pb);
-static unsigned int oti6858_buf_space_avail(struct oti6858_buf *pb);
-static unsigned int oti6858_buf_put(struct oti6858_buf *pb, const char *buf,
-					unsigned int count);
-static unsigned int oti6858_buf_get(struct oti6858_buf *pb, char *buf,
-					unsigned int count);
-
-
 /* device info */
 static struct usb_serial_driver oti6858_device = {
 	.driver = {
@@ -201,7 +180,7 @@ static struct usb_serial_driver oti6858_device = {
 struct oti6858_private {
 	spinlock_t lock;
 
-	struct oti6858_buf *buf;
+	struct kfifo write_fifo;
 	struct oti6858_control_pkt status;
 
 	struct {
@@ -315,7 +294,7 @@ static void send_data(struct work_struct *work)
 	}
 	priv->flags.write_urb_in_use = 1;
 
-	count = oti6858_buf_data_avail(priv->buf);
+	count = kfifo_len(&priv->write_fifo);
 	spin_unlock_irqrestore(&priv->lock, flags);
 	if (count > port->bulk_out_size)
 		count = port->bulk_out_size;
@@ -350,10 +329,9 @@ static void send_data(struct work_struct *work)
 		return;
 	}
 
-	spin_lock_irqsave(&priv->lock, flags);
-	oti6858_buf_get(priv->buf, port->write_urb->transfer_buffer, count);
-	spin_unlock_irqrestore(&priv->lock, flags);
-
+	count = kfifo_out_locked(&priv->write_fifo,
+					port->write_urb->transfer_buffer,
+					count, &priv->lock);
 	port->write_urb->transfer_buffer_length = count;
 	port->write_urb->dev = port->serial->dev;
 	result = usb_submit_urb(port->write_urb, GFP_NOIO);
@@ -376,8 +354,8 @@ static int oti6858_startup(struct usb_serial *serial)
 		priv = kzalloc(sizeof(struct oti6858_private), GFP_KERNEL);
 		if (!priv)
 			break;
-		priv->buf = oti6858_buf_alloc(PL2303_BUF_SIZE);
-		if (priv->buf == NULL) {
+		if (kfifo_alloc(&priv->write_fifo, OTI6858_FIFO_SIZE,
+								GFP_KERNEL)) {
 			kfree(priv);
 			break;
 		}
@@ -397,7 +375,7 @@ static int oti6858_startup(struct usb_serial *serial)
 
 	for (--i; i >= 0; --i) {
 		priv = usb_get_serial_port_data(serial->port[i]);
-		oti6858_buf_free(priv->buf);
+		kfifo_free(&priv->write_fifo);
 		kfree(priv);
 		usb_set_serial_port_data(serial->port[i], NULL);
 	}
@@ -408,16 +386,13 @@ static int oti6858_write(struct tty_struct *tty, struct usb_serial_port *port,
 			const unsigned char *buf, int count)
 {
 	struct oti6858_private *priv = usb_get_serial_port_data(port);
-	unsigned long flags;
 
 	dbg("%s(port = %d, count = %d)", __func__, port->number, count);
 
 	if (!count)
 		return count;
 
-	spin_lock_irqsave(&priv->lock, flags);
-	count = oti6858_buf_put(priv->buf, buf, count);
-	spin_unlock_irqrestore(&priv->lock, flags);
+	count = kfifo_in_locked(&priv->write_fifo, buf, count, &priv->lock);
 
 	return count;
 }
@@ -432,7 +407,7 @@ static int oti6858_write_room(struct tty_struct *tty)
 	dbg("%s(port = %d)", __func__, port->number);
 
 	spin_lock_irqsave(&priv->lock, flags);
-	room = oti6858_buf_space_avail(priv->buf);
+	room = kfifo_avail(&priv->write_fifo);
 	spin_unlock_irqrestore(&priv->lock, flags);
 
 	return room;
@@ -448,7 +423,7 @@ static int oti6858_chars_in_buffer(struct tty_struct *tty)
 	dbg("%s(port = %d)", __func__, port->number);
 
 	spin_lock_irqsave(&priv->lock, flags);
-	chars = oti6858_buf_data_avail(priv->buf);
+	chars = kfifo_len(&priv->write_fifo);
 	spin_unlock_irqrestore(&priv->lock, flags);
 
 	return chars;
@@ -642,7 +617,7 @@ static void oti6858_close(struct usb_serial_port *port)
 
 	spin_lock_irqsave(&priv->lock, flags);
 	/* clear out any remaining data in the buffer */
-	oti6858_buf_clear(priv->buf);
+	kfifo_reset_out(&priv->write_fifo);
 	spin_unlock_irqrestore(&priv->lock, flags);
 
 	dbg("%s(): after buf_clear()", __func__);
@@ -793,7 +768,7 @@ static void oti6858_release(struct usb_serial *serial)
 	for (i = 0; i < serial->num_ports; ++i) {
 		priv = usb_get_serial_port_data(serial->port[i]);
 		if (priv) {
-			oti6858_buf_free(priv->buf);
+			kfifo_free(&priv->write_fifo);
 			kfree(priv);
 		}
 	}
@@ -892,7 +867,7 @@ static void oti6858_read_int_callback(struct urb *urb)
 
 		spin_lock_irqsave(&priv->lock, flags);
 		if (priv->flags.write_urb_in_use == 0
-				&& oti6858_buf_data_avail(priv->buf) != 0) {
+				&& kfifo_len(&priv->write_fifo) != 0) {
 			schedule_delayed_work(&priv->delayed_write_work, 0);
 			resubmit = 0;
 		}
@@ -1014,165 +989,6 @@ static void oti6858_write_bulk_callback(struct urb *urb)
 	}
 }
 
-
-/*
- * oti6858_buf_alloc
- *
- * Allocate a circular buffer and all associated memory.
- */
-static struct oti6858_buf *oti6858_buf_alloc(unsigned int size)
-{
-	struct oti6858_buf *pb;
-
-	if (size == 0)
-		return NULL;
-
-	pb = kmalloc(sizeof(struct oti6858_buf), GFP_KERNEL);
-	if (pb == NULL)
-		return NULL;
-
-	pb->buf_buf = kmalloc(size, GFP_KERNEL);
-	if (pb->buf_buf == NULL) {
-		kfree(pb);
-		return NULL;
-	}
-
-	pb->buf_size = size;
-	pb->buf_get = pb->buf_put = pb->buf_buf;
-
-	return pb;
-}
-
-/*
- * oti6858_buf_free
- *
- * Free the buffer and all associated memory.
- */
-static void oti6858_buf_free(struct oti6858_buf *pb)
-{
-	if (pb) {
-		kfree(pb->buf_buf);
-		kfree(pb);
-	}
-}
-
-/*
- * oti6858_buf_clear
- *
- * Clear out all data in the circular buffer.
- */
-static void oti6858_buf_clear(struct oti6858_buf *pb)
-{
-	if (pb != NULL) {
-		/* equivalent to a get of all data available */
-		pb->buf_get = pb->buf_put;
-	}
-}
-
-/*
- * oti6858_buf_data_avail
- *
- * Return the number of bytes of data available in the circular
- * buffer.
- */
-static unsigned int oti6858_buf_data_avail(struct oti6858_buf *pb)
-{
-	if (pb == NULL)
-		return 0;
-	return (pb->buf_size + pb->buf_put - pb->buf_get) % pb->buf_size;
-}
-
-/*
- * oti6858_buf_space_avail
- *
- * Return the number of bytes of space available in the circular
- * buffer.
- */
-static unsigned int oti6858_buf_space_avail(struct oti6858_buf *pb)
-{
-	if (pb == NULL)
-		return 0;
-	return (pb->buf_size + pb->buf_get - pb->buf_put - 1) % pb->buf_size;
-}
-
-/*
- * oti6858_buf_put
- *
- * Copy data data from a user buffer and put it into the circular buffer.
- * Restrict to the amount of space available.
- *
- * Return the number of bytes copied.
- */
-static unsigned int oti6858_buf_put(struct oti6858_buf *pb, const char *buf,
-					unsigned int count)
-{
-	unsigned int len;
-
-	if (pb == NULL)
-		return 0;
-
-	len  = oti6858_buf_space_avail(pb);
-	if (count > len)
-		count = len;
-
-	if (count == 0)
-		return 0;
-
-	len = pb->buf_buf + pb->buf_size - pb->buf_put;
-	if (count > len) {
-		memcpy(pb->buf_put, buf, len);
-		memcpy(pb->buf_buf, buf+len, count - len);
-		pb->buf_put = pb->buf_buf + count - len;
-	} else {
-		memcpy(pb->buf_put, buf, count);
-		if (count < len)
-			pb->buf_put += count;
-		else /* count == len */
-			pb->buf_put = pb->buf_buf;
-	}
-
-	return count;
-}
-
-/*
- * oti6858_buf_get
- *
- * Get data from the circular buffer and copy to the given buffer.
- * Restrict to the amount of data available.
- *
- * Return the number of bytes copied.
- */
-static unsigned int oti6858_buf_get(struct oti6858_buf *pb, char *buf,
-					unsigned int count)
-{
-	unsigned int len;
-
-	if (pb == NULL)
-		return 0;
-
-	len = oti6858_buf_data_avail(pb);
-	if (count > len)
-		count = len;
-
-	if (count == 0)
-		return 0;
-
-	len = pb->buf_buf + pb->buf_size - pb->buf_get;
-	if (count > len) {
-		memcpy(buf, pb->buf_get, len);
-		memcpy(buf+len, pb->buf_buf, count - len);
-		pb->buf_get = pb->buf_buf + count - len;
-	} else {
-		memcpy(buf, pb->buf_get, count);
-		if (count < len)
-			pb->buf_get += count;
-		else /* count == len */
-			pb->buf_get = pb->buf_buf;
-	}
-
-	return count;
-}
-
 /* module description and (de)initialization */
 
 static int __init oti6858_init(void)