Exynos: uart: s5p: enabling the uart tx/rx fifo

This patch enables the uart tx/rx fifo. Now that fifo is enabled,
the uart read/write functions are modfied to check the UFSTAT register
for fifo status instead of UTRSTAT (as required with fifo's enabled).
Tested by booting linux kernel. Before enabling tx/rx fifo
"Uncompressing linux" message is garbled and after enabling it is proper.

Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
Signed-off-by: Akshay Saraswat <akshay.s@samsung.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>

drivers/serial/serial_s5p.c

@@ -30,6 +30,10 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
+#define RX_FIFO_COUNT_MASK	0xff
+#define RX_FIFO_FULL_MASK	(1 << 8)
+#define TX_FIFO_FULL_MASK	(1 << 24)
+
 static inline struct s5p_uart *s5p_get_base_uart(int dev_index)
 {
 	u32 offset = dev_index * sizeof(struct s5p_uart);
@@ -87,8 +91,8 @@ int serial_init_dev(const int dev_index)
 {
 	struct s5p_uart *const uart = s5p_get_base_uart(dev_index);
 
-	/* reset and enable FIFOs, set triggers to the maximum */
-	writel(0, &uart->ufcon);
+	/* enable FIFOs */
+	writel(0x1, &uart->ufcon);
 	writel(0, &uart->umcon);
 	/* 8N1 */
 	writel(0x3, &uart->ulcon);
@@ -130,7 +134,8 @@ int serial_getc_dev(const int dev_index)
 	struct s5p_uart *const uart = s5p_get_base_uart(dev_index);
 
 	/* wait for character to arrive */
-	while (!(readl(&uart->utrstat) & 0x1)) {
+	while (!(readl(&uart->ufstat) & (RX_FIFO_COUNT_MASK |
+					 RX_FIFO_FULL_MASK))) {
 		if (serial_err_check(dev_index, 0))
 			return 0;
 	}
@@ -146,7 +151,7 @@ void serial_putc_dev(const char c, const int dev_index)
 	struct s5p_uart *const uart = s5p_get_base_uart(dev_index);
 
 	/* wait for room in the tx FIFO */
-	while (!(readl(&uart->utrstat) & 0x2)) {
+	while ((readl(&uart->ufstat) & TX_FIFO_FULL_MASK)) {
 		if (serial_err_check(dev_index, 1))
 			return;
 	}