GeckoUSB/kernelpatch.diff at master · randomdude/GeckoUSB · GitHub

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--- linux-2.6.32.27/drivers/serial/usbgecko.c	2012-03-16 18:28:34.393587508 +0000
+++ ./usbgecko.c	2012-05-24 17:33:16.037171945 +0100
@@ -24,6 +24,8 @@
 #include <linux/tty_flip.h>
 #include <linux/kthread.h>
 #include <linux/delay.h>
+#include <linux/circ_buf.h>
+#define XMITSIZE 256

 #include <linux/exi.h>

@@ -54,6 +56,7 @@
 	struct task_struct *poller;
 	struct mutex mutex;
 	int refcnt;
+	struct circ_buf xmit;
 };

 static struct ug_adapter ug_adapters[2];
@@ -342,6 +345,20 @@
 			}
 			schedule_timeout(1);
 		}
+		// Now try to transmit anything pending.
+		if (adapter) {
+			unsigned long head = ACCESS_ONCE(adapter->xmit.head);
+			unsigned long tail = adapter->xmit.tail;
+			count = CIRC_CNT(head, tail, XMITSIZE);
+			if (count > 0) {
+				if(ug_safe_putc(adapter,
+					adapter->xmit.buf[tail])) {
+					barrier();
+					adapter->xmit.tail = (tail + 1) & (XMITSIZE - 1);
+				}
+			}
+		}
+
 		set_task_state(current, TASK_RUNNING);
 	}

@@ -402,11 +419,37 @@
 	mutex_unlock(&adapter->mutex);
 }

+static int ug_tty_putchar(struct tty_struct *tty, unsigned char ch)
+{
+	struct ug_adapter *adapter = tty->driver_data;
+	struct circ_buf  *xmit = &adapter->xmit;
+	unsigned long head, tail;
+	int index;
+
+	if (!adapter)
+		return -ENODEV;
+
+	index = tty->index;
+	adapter = &ug_adapters[index];
+
+	head = xmit->head;
+	tail = ACCESS_ONCE(xmit->tail);
+
+	if( CIRC_SPACE(head, tail, XMITSIZE) == 0)
+		return 0;
+
+	xmit->buf[head] = ch;
+	barrier();
+	xmit->head = (head + 1) & (XMITSIZE - 1);
+
+	return 1;
+}
+
 static int ug_tty_write(struct tty_struct *tty,
 			 const unsigned char *buf, int count)
 {
 	struct ug_adapter *adapter = tty->driver_data;
-	char *b = (char *)buf;
+	unsigned long head, tail;
 	int index;
 	int i;

@@ -415,19 +458,42 @@

 	index = tty->index;
 	adapter = &ug_adapters[index];
-	for (i = 0; i < count; i++)
-		ug_safe_putc(adapter, *b++);
+
+	head = ACCESS_ONCE(adapter->xmit.head);
+	tail = adapter->xmit.tail;
+
+	// Simply pass all our data to putchar.
+	for(i=0; i<count; i++)
+		ug_tty_putchar(tty, buf[i]);
+
 	return count;
 }

 static int ug_tty_write_room(struct tty_struct *tty)
 {
-	return 0x123; /* whatever */
+	struct ug_adapter *adapter = tty->driver_data;
+
+	if (!adapter)
+		return 0;
+
+	unsigned long head = ACCESS_ONCE(adapter->xmit.head);
+	unsigned long tail = adapter->xmit.tail;
+
+	return CIRC_SPACE(head, tail, XMITSIZE);
 }

 static int ug_tty_chars_in_buffer(struct tty_struct *tty)
 {
-	return 0; /* unbuffered */
+	struct ug_adapter *adapter = tty->driver_data;
+	unsigned long head, tail;
+
+	if (!adapter)
+		return 0;
+
+	head = ACCESS_ONCE(adapter->xmit.head);
+	tail = adapter->xmit.tail;
+
+	return CIRC_CNT(head, tail, XMITSIZE);
 }


@@ -435,6 +501,7 @@
 	.open = ug_tty_open,
 	.close = ug_tty_close,
 	.write = ug_tty_write,
+	.put_char = ug_tty_putchar,
 	.write_room = ug_tty_write_room,
 	.chars_in_buffer = ug_tty_chars_in_buffer,
 };
@@ -507,6 +574,13 @@
 	adapter->poller = ERR_PTR(-EINVAL);
 	mutex_init(&adapter->mutex);
 	adapter->refcnt = 0;
+	adapter->xmit.head = adapter->xmit.tail = 0;
+	adapter->xmit.buf = kmalloc(XMITSIZE, GFP_KERNEL);
+	if(!adapter->xmit.buf)
+	{
+		drv_printk(KERN_ERR, "USB Gecko: kmalloc failed\n");
+		return 1;
+	}

 	adapter->exi_device = exi_device_get(exi_device);
 	exi_set_drvdata(exi_device, adapter);