[SERIAL] 8250: set divisor register correctly for AMD Alchemy SoC uart

Alchemy SoC uart have got a non-standard divisor register that needs some
special handling.

This patch adds divisor read/write functions with test and special
handling for Alchemy internal uart.

Signed-off-by: Jon Anders Haugum <jonah@omegav.ntnu.no>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 42 insertions, 13 deletions

diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index d641ac4e976e..9cc74712795d 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -362,6 +362,40 @@ serial_out(struct uart_8250_port *up, int offset, int value)
 #define serial_inp(up, offset)          serial_in(up, offset)
 #define serial_outp(up, offset, value)  serial_out(up, offset, value)
 
+/* Uart divisor latch read */
+static inline int _serial_dl_read(struct uart_8250_port *up)
+{
+        return serial_inp(up, UART_DLL) | serial_inp(up, UART_DLM) << 8;
+}
+
+/* Uart divisor latch write */
+static inline void _serial_dl_write(struct uart_8250_port *up, int value)
+{
+        serial_outp(up, UART_DLL, value & 0xff);
+        serial_outp(up, UART_DLM, value >> 8 & 0xff);
+}
+
+#ifdef CONFIG_SERIAL_8250_AU1X00
+/* Au1x00 haven't got a standard divisor latch */
+static int serial_dl_read(struct uart_8250_port *up)
+{
+        if (up->port.iotype == UPIO_AU)
+                return __raw_readl(up->port.membase + 0x28);
+        else
+                return _serial_dl_read(up);
+}
+
+static void serial_dl_write(struct uart_8250_port *up, int value)
+{
+        if (up->port.iotype == UPIO_AU)
+                __raw_writel(value, up->port.membase + 0x28);
+        else
+                _serial_dl_write(up, value);
+}
+#else
+#define serial_dl_read(up) _serial_dl_read(up)
+#define serial_dl_write(up, value) _serial_dl_write(up, value)
+#endif
 
 /*
  * For the 16C950
@@ -494,7 +528,8 @@ static void disable_rsa(struct uart_8250_port *up)
  */
 static int size_fifo(struct uart_8250_port *up)
 {
-        unsigned char old_fcr, old_mcr, old_dll, old_dlm, old_lcr;
+        unsigned char old_fcr, old_mcr, old_lcr;
+        unsigned short old_dl;
         int count;
 
         old_lcr = serial_inp(up, UART_LCR);
@@ -505,10 +540,8 @@ static int size_fifo(struct uart_8250_port *up)
                     UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
         serial_outp(up, UART_MCR, UART_MCR_LOOP);
         serial_outp(up, UART_LCR, UART_LCR_DLAB);
-        old_dll = serial_inp(up, UART_DLL);
-        old_dlm = serial_inp(up, UART_DLM);
-        serial_outp(up, UART_DLL, 0x01);
-        serial_outp(up, UART_DLM, 0x00);
+        old_dl = serial_dl_read(up);
+        serial_dl_write(up, 0x0001);
         serial_outp(up, UART_LCR, 0x03);
         for (count = 0; count < 256; count++)
                 serial_outp(up, UART_TX, count);
@@ -519,8 +552,7 @@ static int size_fifo(struct uart_8250_port *up)
         serial_outp(up, UART_FCR, old_fcr);
         serial_outp(up, UART_MCR, old_mcr);
         serial_outp(up, UART_LCR, UART_LCR_DLAB);
-        serial_outp(up, UART_DLL, old_dll);
-        serial_outp(up, UART_DLM, old_dlm);
+        serial_dl_write(up, old_dl);
         serial_outp(up, UART_LCR, old_lcr);
 
         return count;
@@ -750,8 +782,7 @@ static void autoconfig_16550a(struct uart_8250_port *up)
 
                         serial_outp(up, UART_LCR, 0xE0);
 
-                        quot = serial_inp(up, UART_DLM) << 8;
-                        quot += serial_inp(up, UART_DLL);
+                        quot = serial_dl_read(up);
                         quot <<= 3;
 
                         status1 = serial_in(up, 0x04); /* EXCR1 */
@@ -759,8 +790,7 @@ static void autoconfig_16550a(struct uart_8250_port *up)
                         status1 |= 0x10;  /* 1.625 divisor for baud_base --> 921600 */
                         serial_outp(up, 0x04, status1);
                         
-                        serial_outp(up, UART_DLL, quot & 0xff);
-                        serial_outp(up, UART_DLM, quot >> 8);
+                        serial_dl_write(up, quot);
 
                         serial_outp(up, UART_LCR, 0);
 
@@ -1862,8 +1892,7 @@ serial8250_set_termios(struct uart_port *port, struct termios *termios,
                 serial_outp(up, UART_LCR, cval | UART_LCR_DLAB);/* set DLAB */
         }
 
-        serial_outp(up, UART_DLL, quot & 0xff);         /* LS of divisor */
-        serial_outp(up, UART_DLM, quot >> 8);           /* MS of divisor */
+        serial_dl_write(up, quot);
 
         /*
          * LCR DLAB must be set to enable 64-byte FIFO mode. If the FCR