[PATCH] Create configuration option for restricted ns16550 functions

[Ron Madrid]

This patch will create a configuration option for a minimum configuration for
the ns16550 serial driver at drivers/serial/ns16550.c which will exclude all
functions with exception of NS16550_putc and NS16550_init.  This will be used
primarily to save space and remove unused code from builds in which space is
limited.

Signed-off-by: Ron Madrid <ron_madrid at sbcglobal.net>

changed CONFIG_NS* to CONFIG_SYS_NS*, fixed these compiler errors:

undefined reference to `NS16550_reinit'
undefined reference to `NS16550_tstc'
undefined reference to `NS16550_getc'

and made declarations macros to save space, replaced functions that had
returned values with 0.

Made SIMPC8313 builds turn on the configuration option by default to
fix the "NAND bootstrap too big" error when building u-boot-spl.

Signed-off-by: Kim Phillips <kim.phillips at freescale.com>
---
 README                      |    7 +++++++
 drivers/serial/ns16550.c    |    5 ++++-
 include/configs/SIMPC8313.h |    1 +
 include/ns16550.h           |    6 ++++++
 4 files changed, 18 insertions(+), 1 deletions(-)

diff --git a/README b/README
index b64c159..48d3f6d 100644
--- a/README
+++ b/README
@@ -2458,6 +2458,13 @@ use the "saveenv" command to store a valid environment.
 - CONFIG_SYS_64BIT_STRTOUL:
 		Adds simple_strtoull that returns a 64bit value
 
+- CONFIG_NS16550_MIN_FUNCTIONS:
+		Define this if you desire to only have use of the NS16550_init
+		and NS16550_putc functions for the serial driver located at
+		drivers/serial/ns16550.c.  This option is useful for saving
+		space for already greatly restricted images, including but not
+		limited to NAND_SPL configurations.
+
 Low Level (hardware related) configuration options:
 ---------------------------------------------------
 
diff --git a/drivers/serial/ns16550.c b/drivers/serial/ns16550.c
index 93c2243..25a0c5a 100644
--- a/drivers/serial/ns16550.c
+++ b/drivers/serial/ns16550.c
@@ -39,6 +39,7 @@ void NS16550_init (NS16550_t com_port, int baud_divisor)
 #endif
 }
 
+#ifndef CONFIG_SYS_NS16550_MIN_FUNCTIONS
 void NS16550_reinit (NS16550_t com_port, int baud_divisor)
 {
 	com_port->ier = 0x00;
@@ -53,6 +54,7 @@ void NS16550_reinit (NS16550_t com_port, int baud_divisor)
 	com_port->dlm = (baud_divisor >> 8) & 0xff;
 	com_port->lcr = LCRVAL;
 }
+#endif /* CONFIG_SYS_NS16550_MIN_FUNCTIONS */
 
 void NS16550_putc (NS16550_t com_port, char c)
 {
@@ -60,6 +62,7 @@ void NS16550_putc (NS16550_t com_port, char c)
 	com_port->thr = c;
 }
 
+#ifndef CONFIG_SYS_NS16550_MIN_FUNCTIONS
 char NS16550_getc (NS16550_t com_port)
 {
 	while ((com_port->lsr & LSR_DR) == 0) {
@@ -75,5 +78,5 @@ int NS16550_tstc (NS16550_t com_port)
 {
 	return ((com_port->lsr & LSR_DR) != 0);
 }
-
+#endif /* CONFIG_SYS_NS16550_MIN_FUNCTIONS */
 #endif
diff --git a/include/configs/SIMPC8313.h b/include/configs/SIMPC8313.h
index f62a705..6219722 100644
--- a/include/configs/SIMPC8313.h
+++ b/include/configs/SIMPC8313.h
@@ -205,6 +205,7 @@
 #define CONFIG_SYS_NS16550
 #define CONFIG_SYS_NS16550_SERIAL
 #define CONFIG_SYS_NS16550_REG_SIZE	1
+#define CONFIG_SYS_NS16550_MIN_FUNCTIONS
 
 #define CONFIG_SYS_BAUDRATE_TABLE	\
 	{300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 115200}
diff --git a/include/ns16550.h b/include/ns16550.h
index e6ade61..dbaacfc 100644
--- a/include/ns16550.h
+++ b/include/ns16550.h
@@ -154,6 +154,12 @@ typedef volatile struct NS16550 *NS16550_t;
 
 void	NS16550_init   (NS16550_t com_port, int baud_divisor);
 void	NS16550_putc   (NS16550_t com_port, char c);
+#ifndef CONFIG_SYS_NS16550_MIN_FUNCTIONS
 char	NS16550_getc   (NS16550_t com_port);
 int	NS16550_tstc   (NS16550_t com_port);
 void	NS16550_reinit (NS16550_t com_port, int baud_divisor);
+#else
+#define NS16550_getc(com_port) 0
+#define NS16550_tstc(com_port) 0
+#define NS16550_reinit(com_port, baud_divisor)
+#endif
-- 
1.6.1.3