linux-kernel - [PATCH] m68k: mvme147: Reinstate early console

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Message-Id: <b6112556472c657762f064ec5328f153e3ed03cd.1727926187.git.fthain@linux-m68k.org>
Date: Thu, 03 Oct 2024 13:29:47 +1000
From: Finn Thain <fthain@...ux-m68k.org>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
Cc: "Daniel Palmer" <daniel@...f.com>,
    stable@...nel.org,
    linux-m68k@...ts.linux-m68k.org,
    linux-kernel@...r.kernel.org
Subject: [PATCH] m68k: mvme147: Reinstate early console

From: Daniel Palmer <daniel@...f.com>

Commit a38eaa07a0ce ("m68k/mvme147: config.c - Remove unused functions"),
removed the console functionality for the mvme147 instead of wiring it
up to an early console. Put the console write function back and wire it up
like mvme16x does so it's possible to see Linux boot on this fine hardware
once more.

Cc: Daniel Palmer <daniel@...f.com>
Cc: stable@...nel.org
Fixes: a38eaa07a0ce ("m68k/mvme147: config.c - Remove unused functions")
Signed-off-by: Daniel Palmer <daniel@...f.com>
Reviewed-by: Finn Thain <fthain@...ux-m68k.org>
---
 arch/m68k/kernel/early_printk.c |  3 +++
 arch/m68k/mvme147/config.c      | 27 +++++++++++++++++++++++++++
 arch/m68k/mvme147/mvme147.h     |  6 ++++++
 3 files changed, 36 insertions(+)
 create mode 100644 arch/m68k/mvme147/mvme147.h

diff --git a/arch/m68k/kernel/early_printk.c b/arch/m68k/kernel/early_printk.c
index 3cc944df04f6..d9399be89ad3 100644
--- a/arch/m68k/kernel/early_printk.c
+++ b/arch/m68k/kernel/early_printk.c
@@ -14,6 +14,7 @@
 
 
 #include "../mvme16x/mvme16x.h"
+#include "../mvme147/mvme147.h"
 
 asmlinkage void __init debug_cons_nputs(const char *s, unsigned n);
 
@@ -24,6 +25,8 @@ static void __ref debug_cons_write(struct console *c,
       defined(CONFIG_COLDFIRE))
 	if (MACH_IS_MVME16x)
 		mvme16x_cons_write(c, s, n);
+	else if (MACH_IS_MVME147)
+		mvme147_scc_write(c, s, n);
 	else
 		debug_cons_nputs(s, n);
 #endif
diff --git a/arch/m68k/mvme147/config.c b/arch/m68k/mvme147/config.c
index e2560c6d10b4..536244a181ef 100644
--- a/arch/m68k/mvme147/config.c
+++ b/arch/m68k/mvme147/config.c
@@ -33,6 +33,7 @@
 #include <asm/mvme147hw.h>
 #include <asm/config.h>
 
+#include "mvme147.h"
 
 static void mvme147_get_model(char *model);
 extern void mvme147_sched_init(void);
@@ -177,3 +178,29 @@ static u64 mvme147_read_clk(struct clocksource *cs)
 
 	return ticks;
 }
+
+#define SCC_DELAY do { __asm__ __volatile__ ("nop; nop;"); } while (0)
+
+static void scc_write(char ch)
+{
+	do {
+		SCC_DELAY;
+	} while (!(in_8(M147_SCC_A_ADDR) & BIT(2)));
+	SCC_DELAY;
+	out_8(M147_SCC_A_ADDR, 8);
+	SCC_DELAY;
+	out_8(M147_SCC_A_ADDR, ch);
+}
+
+void mvme147_scc_write(struct console *co, const char *str, unsigned int count)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	while (count--)	{
+		if (*str == '\n')
+			scc_write('\r');
+		scc_write(*str++);
+	}
+	local_irq_restore(flags);
+}
diff --git a/arch/m68k/mvme147/mvme147.h b/arch/m68k/mvme147/mvme147.h
new file mode 100644
index 000000000000..140bc98b0102
--- /dev/null
+++ b/arch/m68k/mvme147/mvme147.h
@@ -0,0 +1,6 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+struct console;
+
+/* config.c */
+void mvme147_scc_write(struct console *co, const char *str, unsigned int count);
-- 
2.39.5