serial: pxa: fine-tune clk useage

1) add clk_enable/disable in serial_pxa_console_write()
2) add clk_prepare() to follow common clock driver
Signed-off-by: Yi Zhang <yizhang@marvell.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/pxa.c

@@ -672,7 +672,7 @@ serial_pxa_console_write(struct console *co, const char *s, unsigned int count)
 	unsigned long flags;
 	int locked = 1;
 
-
+	clk_enable(up->clk);
 	local_irq_save(flags);
 	if (up->port.sysrq)
 		locked = 0;
@@ -699,6 +699,7 @@ serial_pxa_console_write(struct console *co, const char *s, unsigned int count)
 	if (locked)
 		spin_unlock(&up->port.lock);
 	local_irq_restore(flags);
+	clk_disable(up->clk);
 
 }
 
@@ -896,6 +897,12 @@ static int serial_pxa_probe(struct platform_device *dev)
 		goto err_free;
 	}
 
+	ret = clk_prepare(sport->clk);
+	if (ret) {
+		clk_put(sport->clk);
+		goto err_free;
+	}
+
 	sport->port.type = PORT_PXA;
 	sport->port.iotype = UPIO_MEM;
 	sport->port.mapbase = mmres->start;
@@ -927,6 +934,7 @@ static int serial_pxa_probe(struct platform_device *dev)
 	return 0;
 
  err_clk:
+	clk_unprepare(sport->clk);
 	clk_put(sport->clk);
  err_free:
 	kfree(sport);
@@ -940,6 +948,8 @@ static int serial_pxa_remove(struct platform_device *dev)
 	platform_set_drvdata(dev, NULL);
 
 	uart_remove_one_port(&serial_pxa_reg, &sport->port);
+
+	clk_unprepare(sport->clk);
 	clk_put(sport->clk);
 	kfree(sport);