path: root/arch/m68k
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authorFinn Thain <fthain@telegraphics.com.au>2014-01-13 00:56:38 +1100
committerGeert Uytterhoeven <geert@linux-m68k.org>2014-01-19 11:53:22 +0100
commit56931d73697c99ecf7aba6ae86c94d3a2d15d596 (patch)
tree9b23e4520d20e07cdab407f790c1af96735cd33e /arch/m68k
parenta0b7b242261c8c1097925663bf44d51c1e357e58 (diff)
m68k/mac: Make SCC reset work more reliably
For SCC initialization we cannot assume that the control register is in the correct state to accept a register pointer. So first read from the control register in order to "sync" up. Signed-off-by: Finn Thain <fthain@telegraphics.com.au> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Diffstat (limited to 'arch/m68k')
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/m68k/kernel/head.S b/arch/m68k/kernel/head.S
index 7d7913f5dce..4c99bab7e66 100644
--- a/arch/m68k/kernel/head.S
+++ b/arch/m68k/kernel/head.S
@@ -2915,7 +2915,9 @@ func_start serial_init,%d0/%d1/%a0/%a1
#if defined(MAC_USE_SCC_A) || defined(MAC_USE_SCC_B)
movel %pc@(L(mac_sccbase)),%a0
- /* Reset SCC device */
+ /* Reset SCC register pointer */
+ moveb %a0@(mac_scc_cha_a_ctrl_offset),%d0
+ /* Reset SCC device: write register pointer then register value */
moveb #9,%a0@(mac_scc_cha_a_ctrl_offset)
moveb #0xc0,%a0@(mac_scc_cha_a_ctrl_offset)
/* Wait for 5 PCLK cycles, which is about 68 CPU cycles */