Diff of /arch/m68k/kernel/head.S [c46f46] .. [83adc1] Maximize Restore

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--- a/arch/m68k/kernel/head.S
+++ b/arch/m68k/kernel/head.S
@@ -2722,6 +2722,7 @@
 #define MAC_USE_SCC_B /* Printer port */
 
 #if defined(MAC_USE_SCC_A) || defined(MAC_USE_SCC_B)
+/* Initialisation table for SCC with 3.6864 MHz PCLK */
 L(scc_initable_mac):
 	.byte	4,0x44		/* x16, 1 stopbit, no parity */
 	.byte	3,0xc0		/* receiver: 8 bpc */
@@ -2744,14 +2745,12 @@
 #define USE_MFP
 
 #if defined(USE_SCC_A) || defined(USE_SCC_B)
-#define USE_SCC
-/* Initialisation table for SCC */
-L(scc_initable):
-	.byte	9,12		/* Reset */
+/* Initialisation table for SCC with 7.9872 MHz PCLK */
+/* PCLK == 8.0539 gives baud == 9680.1 */
+L(scc_initable_atari):
 	.byte	4,0x44		/* x16, 1 stopbit, no parity */
 	.byte	3,0xc0		/* receiver: 8 bpc */
 	.byte	5,0xe2		/* transmitter: 8 bpc, assert dtr/rts */
-	.byte	9,0		/* no interrupts */
 	.byte	10,0		/* NRZ */
 	.byte	11,0x50		/* use baud rate generator */
 	.byte	12,24,13,0	/* 9600 baud */
@@ -2800,7 +2799,7 @@
  */
 
 /*
- * Initialize serial port hardware for 9600/8/1
+ * Initialize serial port hardware
  */
 func_start	serial_init,%d0/%d1/%a0/%a1
 	/*
@@ -2810,7 +2809,7 @@
 	 *		d0 = boot info offset
 	 *	CONFIG_ATARI
 	 *		a0 = address of SCC
-	 *		a1 = Liobase address/address of scc_initable
+	 *		a1 = Liobase address/address of scc_initable_atari
 	 *		d0 = init data for serial port
 	 *	CONFIG_MAC
 	 *		a0 = address of SCC
@@ -2846,9 +2845,21 @@
 	moveb	%a1@(LPSG_READ),%d0
 	bset	#5,%d0
 	moveb	%d0,%a1@(LPSG_WRITE)
-#elif defined(USE_SCC)
+#elif defined(USE_SCC_A) || defined(USE_SCC_B)
 	lea	%a1@(LSCC_CTRL),%a0
-	lea	%pc@(L(scc_initable)),%a1
+	/* Reset SCC register pointer */
+	moveb	%a0@,%d0
+	/* Reset SCC device: write register pointer then register value */
+	moveb	#9,%a0@
+	moveb	#0xc0,%a0@
+	/* Wait for 5 PCLK cycles, which is about 63 CPU cycles */
+	/* 5 / 7.9872 MHz = approx. 0.63 us = 63 / 100 MHz */
+	movel	#32,%d0
+2:
+	subq	#1,%d0
+	jne	2b
+	/* Initialize channel */
+	lea	%pc@(L(scc_initable_atari)),%a1
 2:	moveb	%a1@+,%d0
 	jmi	3f
 	moveb	%d0,%a0@
@@ -3017,7 +3028,7 @@
 	nop
 	bset	#5,%d0
 	moveb	%d0,%a1@(LPSG_WRITE)
-#elif defined(USE_SCC)
+#elif defined(USE_SCC_A) || defined(USE_SCC_B)
 3:	btst	#2,%a1@(LSCC_CTRL)
 	jeq	3b
 	moveb	%d0,%a1@(LSCC_DATA)