Blackfin: fix accidental reset in some boot modes

commit 0de4adfb8c9674fa1572b0ff1371acc94b0be901 upstream.

We read the SWRST (Software Reset) register to get at the last reset
state, and then we may configure the DOUBLE_FAULT bit to control behavior
when a double fault occurs.  But if the lower bits of the register is
already set (like UART boot mode on a BF54x), we inadvertently make the
system reset by writing to the SYSTEM_RESET field at the same time.  So
make sure the lower 4 bits are always cleared.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/arch/blackfin/kernel/setup.c b/arch/blackfin/kernel/setup.c
index a58687bdee6a6580031d6903526774c3f35e1625..b550bae34e4b5b4a0b712f95ef603f5abeda87c9 100644 (file)
--- a/arch/blackfin/kernel/setup.c
+++ b/arch/blackfin/kernel/setup.c
@@ -831,7 +831,8 @@ void __init setup_arch(char **cmdline_p)
     defined(CONFIG_BF538) || defined(CONFIG_BF539)
        _bfin_swrst = bfin_read_SWRST();
 #else
-       _bfin_swrst = bfin_read_SYSCR();
+       /* Clear boot mode field */
+       _bfin_swrst = bfin_read_SYSCR() & ~0xf;
 #endif
 
 #ifdef CONFIG_DEBUG_DOUBLEFAULT_PRINT