[PATCH] dz.c: Use a helper to cast from "struct uart_port *"

["Maciej W. Rozycki" <macro@xxxxxxxxxxxxxx>]

 Replace all casts from "struct uart_port *" to "struct dz_port *" with a 
construct based on container_of().  This makes the conversion work 
irrespective of where the former struct is located within the latter.

 By popular request I have implemented it as an inline function rather 
than a macro this time.

Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxxxxxx>
---
 Tested with checkpatch.pl and at the run-time -- MIPS/Linux on a
DECstation 5000/200.

 Please apply,

  Maciej

patch-mips-2.6.23-rc5-20070904-dz-to_dport-2
diff -up --recursive --new-file linux-mips-2.6.23-rc5-20070904.macro/drivers/serial/dz.c linux-mips-2.6.23-rc5-20070904/drivers/serial/dz.c
--- linux-mips-2.6.23-rc5-20070904.macro/drivers/serial/dz.c	2007-10-13 12:57:52.000000000 +0000
+++ linux-mips-2.6.23-rc5-20070904/drivers/serial/dz.c	2007-10-13 19:48:07.000000000 +0000
@@ -65,6 +65,11 @@ struct dz_port {
 
 static struct dz_port dz_ports[DZ_NB_PORT];
 
+static inline struct dz_port *to_dport(struct uart_port *uport)
+{
+	return container_of(uport, struct dz_port, port);
+}
+
 /*
  * ------------------------------------------------------------
  * dz_in () and dz_out ()
@@ -103,7 +108,7 @@ static inline void dz_out(struct dz_port
 
 static void dz_stop_tx(struct uart_port *uport)
 {
-	struct dz_port *dport = (struct dz_port *)uport;
+	struct dz_port *dport = to_dport(uport);
 	unsigned short tmp, mask = 1 << dport->port.line;
 
 	tmp = dz_in(dport, DZ_TCR);	/* read the TX flag */
@@ -113,7 +118,7 @@ static void dz_stop_tx(struct uart_port 
 
 static void dz_start_tx(struct uart_port *uport)
 {
-	struct dz_port *dport = (struct dz_port *)uport;
+	struct dz_port *dport = to_dport(uport);
 	unsigned short tmp, mask = 1 << dport->port.line;
 
 	tmp = dz_in(dport, DZ_TCR);	/* read the TX flag */
@@ -123,7 +128,7 @@ static void dz_start_tx(struct uart_port
 
 static void dz_stop_rx(struct uart_port *uport)
 {
-	struct dz_port *dport = (struct dz_port *)uport;
+	struct dz_port *dport = to_dport(uport);
 
 	dport->cflag &= ~DZ_CREAD;
 	dz_out(dport, DZ_LPR, dport->cflag | dport->port.line);
@@ -347,7 +352,7 @@ static unsigned int dz_get_mctrl(struct 
 	/*
 	 * FIXME: Handle the 3100/5000 as appropriate. --macro
 	 */
-	struct dz_port *dport = (struct dz_port *)uport;
+	struct dz_port *dport = to_dport(uport);
 	unsigned int mctrl = TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
 
 	if (dport->port.line == DZ_MODEM) {
@@ -363,7 +368,7 @@ static void dz_set_mctrl(struct uart_por
 	/*
 	 * FIXME: Handle the 3100/5000 as appropriate. --macro
 	 */
-	struct dz_port *dport = (struct dz_port *)uport;
+	struct dz_port *dport = to_dport(uport);
 	unsigned short tmp;
 
 	if (dport->port.line == DZ_MODEM) {
@@ -385,7 +390,7 @@ static void dz_set_mctrl(struct uart_por
  */
 static int dz_startup(struct uart_port *uport)
 {
-	struct dz_port *dport = (struct dz_port *)uport;
+	struct dz_port *dport = to_dport(uport);
 	unsigned long flags;
 	unsigned short tmp;
 
@@ -411,7 +416,7 @@ static int dz_startup(struct uart_port *
  */
 static void dz_shutdown(struct uart_port *uport)
 {
-	struct dz_port *dport = (struct dz_port *)uport;
+	struct dz_port *dport = to_dport(uport);
 	unsigned long flags;
 
 	spin_lock_irqsave(&dport->port.lock, flags);
@@ -433,7 +438,7 @@ static void dz_shutdown(struct uart_port
  */
 static unsigned int dz_tx_empty(struct uart_port *uport)
 {
-	struct dz_port *dport = (struct dz_port *)uport;
+	struct dz_port *dport = to_dport(uport);
 	unsigned short tmp, mask = 1 << dport->port.line;
 
 	tmp = dz_in(dport, DZ_TCR);
@@ -448,7 +453,7 @@ static void dz_break_ctl(struct uart_por
 	 * FIXME: Can't access BREAK bits in TDR easily;
 	 * reuse the code for polled TX. --macro
 	 */
-	struct dz_port *dport = (struct dz_port *)uport;
+	struct dz_port *dport = to_dport(uport);
 	unsigned long flags;
 	unsigned short tmp, mask = 1 << dport->port.line;
 
@@ -465,7 +470,7 @@ static void dz_break_ctl(struct uart_por
 static void dz_set_termios(struct uart_port *uport, struct ktermios *termios,
 			   struct ktermios *old_termios)
 {
-	struct dz_port *dport = (struct dz_port *)uport;
+	struct dz_port *dport = to_dport(uport);
 	unsigned long flags;
 	unsigned int cflag, baud;
 
@@ -672,7 +677,7 @@ static void dz_reset(struct dz_port *dpo
  */
 static void dz_console_putchar(struct uart_port *uport, int ch)
 {
-	struct dz_port *dport = (struct dz_port *)uport;
+	struct dz_port *dport = to_dport(uport);
 	unsigned long flags;
 	unsigned short csr, tcr, trdy, mask;
 	int loops = 10000;