[ARM] S3C: Add UART FIFO selection during arch decompression

Add a configuration option to start the UART FIFOs during the
decompressions sequence to improve boot time when the bootloader
fails to enable the UART FIFOs.

For example, the SMDK6410 UBoot 1.1.6 leaves the FIFOs off.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>

diff --git a/arch/arm/plat-s3c/Kconfig b/arch/arm/plat-s3c/Kconfig
index 31656c33e05ebdb60994a391711203f44bf69901..10c1dd3cd463852452e809a1fd4a4a11ac6187aa 100644 (file)
--- a/arch/arm/plat-s3c/Kconfig
+++ b/arch/arm/plat-s3c/Kconfig
@@ -57,6 +57,14 @@ config S3C_BOOT_ERROR_RESET
          Say y here to use the watchdog to reset the system if the
          kernel decompressor detects an error during decompression.
 
+config S3C_BOOT_UART_FORCE_FIFO
+       bool "Force UART FIFO on during boot process"
+       depends on PLAT_S3C
+       default y
+       help
+         Say Y here to force the UART FIFOs on during the kernel
+        uncompressor
+
 comment "Power management"
 
 config S3C2410_PM_DEBUG

diff --git a/arch/arm/plat-s3c/include/plat/uncompress.h b/arch/arm/plat-s3c/include/plat/uncompress.h
index 8a8a927292e065e1961d0a09aeab5972c03cde34..2c39a309aeb0f72e27bcadbf7b31d63deb69c056 100644 (file)
--- a/arch/arm/plat-s3c/include/plat/uncompress.h
+++ b/arch/arm/plat-s3c/include/plat/uncompress.h
@@ -139,6 +139,28 @@ static void arch_decomp_error(const char *x)
 
 static void error(char *err);
 
+#ifdef CONFIG_S3C_BOOT_UART_FORCE_FIFO
+static inline void arch_enable_uart_fifo(void)
+{
+       u32 fifocon = uart_rd(S3C2410_UFCON);
+
+       if (!(fifocon & S3C2410_UFCON_FIFOMODE)) {
+               fifocon |= S3C2410_UFCON_RESETBOTH;
+               uart_wr(S3C2410_UFCON, fifocon);
+
+               /* wait for fifo reset to complete */
+               while (1) {
+                       fifocon = uart_rd(S3C2410_UFCON);
+                       if (!(fifocon & S3C2410_UFCON_RESETBOTH))
+                               break;
+               }
+       }
+}
+#else
+#define arch_enable_uart_fifo() do { } while(0)
+#endif
+
+
 static void
 arch_decomp_setup(void)
 {
@@ -149,6 +171,12 @@ arch_decomp_setup(void)
 
        arch_detect_cpu();
        arch_decomp_wdog_start();
+
+       /* Enable the UART FIFOs if they where not enabled and our
+        * configuration says we should turn them on.
+        */
+
+       arch_enable_uart_fifo();
 }