[SERIAL] Clean up serial_core.c write functions.

Since the tty layer now takes care of user space writes,
__uart_user_write() and associated temporary buffer and temporary
buffer semaphore have all become unnecessary.  There's also little
point in having __uart_kern_write() separate from uart_write(), so
combine the two together.

Adrian Bunk kindly provided the patch to remove __uart_user_write().
The rest of the work is rmk's.

Signed-off-by: Adrian Bunk
Signed-off-by: Russell King <rmk@arm.linux.org.uk>

drivers/serial/serial_core.c

@@ -162,8 +162,6 @@ static int uart_startup(struct uart_state *state, int init_hw)
 			return -ENOMEM;
 
 		info->xmit.buf = (unsigned char *) page;
-		info->tmpbuf = info->xmit.buf + UART_XMIT_SIZE;
-		init_MUTEX(&info->tmpbuf_sem);
 		uart_circ_clear(&info->xmit);
 	}
 
@@ -238,7 +236,6 @@ static void uart_shutdown(struct uart_state *state)
 	if (info->xmit.buf) {
 		free_page((unsigned long)info->xmit.buf);
 		info->xmit.buf = NULL;
-		info->tmpbuf = NULL;
 	}
 
 	/*
@@ -450,53 +447,30 @@ __uart_put_char(struct uart_port *port, struct circ_buf *circ, unsigned char c)
 	spin_unlock_irqrestore(&port->lock, flags);
 }
 
-static inline int
-__uart_user_write(struct uart_port *port, struct circ_buf *circ,
-		  const unsigned char __user *buf, int count)
+static void uart_put_char(struct tty_struct *tty, unsigned char ch)
 {
-	unsigned long flags;
-	int c, ret = 0;
-
-	if (down_interruptible(&port->info->tmpbuf_sem))
-		return -EINTR;
-
-	while (1) {
-		int c1;
-		c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE);
-		if (count < c)
-			c = count;
-		if (c <= 0)
-			break;
+	struct uart_state *state = tty->driver_data;
 
-		c -= copy_from_user(port->info->tmpbuf, buf, c);
-		if (!c) {
-			if (!ret)
-				ret = -EFAULT;
-			break;
-		}
-		spin_lock_irqsave(&port->lock, flags);
-		c1 = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE);
-		if (c1 < c)
-			c = c1;
-		memcpy(circ->buf + circ->head, port->info->tmpbuf, c);
-		circ->head = (circ->head + c) & (UART_XMIT_SIZE - 1);
-		spin_unlock_irqrestore(&port->lock, flags);
-		buf += c;
-		count -= c;
-		ret += c;
-	}
-	up(&port->info->tmpbuf_sem);
+	__uart_put_char(state->port, &state->info->xmit, ch);
+}
 
-	return ret;
+static void uart_flush_chars(struct tty_struct *tty)
+{
+	uart_start(tty);
 }
 
-static inline int
-__uart_kern_write(struct uart_port *port, struct circ_buf *circ,
-		  const unsigned char *buf, int count)
+static int
+uart_write(struct tty_struct *tty, const unsigned char * buf, int count)
 {
+	struct uart_state *state = tty->driver_data;
+	struct uart_port *port = state->port;
+	struct circ_buf *circ = &state->info->xmit;
 	unsigned long flags;
 	int c, ret = 0;
 
+	if (!circ->buf)
+		return 0;
+
 	spin_lock_irqsave(&port->lock, flags);
 	while (1) {
 		c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE);
@@ -512,33 +486,6 @@ __uart_kern_write(struct uart_port *port, struct circ_buf *circ,
 	}
 	spin_unlock_irqrestore(&port->lock, flags);
 
-	return ret;
-}
-
-static void uart_put_char(struct tty_struct *tty, unsigned char ch)
-{
-	struct uart_state *state = tty->driver_data;
-
-	__uart_put_char(state->port, &state->info->xmit, ch);
-}
-
-static void uart_flush_chars(struct tty_struct *tty)
-{
-	uart_start(tty);
-}
-
-static int
-uart_write(struct tty_struct *tty, const unsigned char * buf, int count)
-{
-	struct uart_state *state = tty->driver_data;
-	int ret;
-
-	if (!state->info->xmit.buf)
-		return 0;
-
-	ret = __uart_kern_write(state->port, &state->info->xmit,
-				buf, count);
-
 	uart_start(tty);
 	return ret;
 }

include/linux/serial_core.h

@@ -246,7 +246,7 @@ struct uart_state {
 	struct semaphore	sem;
 };
 
-#define UART_XMIT_SIZE 1024
+#define UART_XMIT_SIZE	PAGE_SIZE
 /*
  * This is the state information which is only valid when the port
  * is open; it may be freed by the core driver once the device has
@@ -268,9 +268,6 @@ struct uart_info {
 #define UIF_NORMAL_ACTIVE	(1 << 29)
 #define UIF_INITIALIZED		(1 << 31)
 
-	unsigned char		*tmpbuf;
-	struct semaphore	tmpbuf_sem;
-
 	int			blocked_open;
 
 	struct tasklet_struct	tlet;