lib: Rewrite qemu-armv7 ramdetect

* Move armv7 RAM dection to a common place
* Enable it for all emulated platforms
* Use 32bit probe values and restore memory even on failure
* Use the new logic on the following boards:
** qemu-armv7
** qemu-riscv

Tested on qemu-system-riscv:
Fixes kernel panic due to wrong memory limits reported.

Change-Id: I37386c6a95bfc3b7b25aeae32c6e14cff9913513
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33934
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

5 files changed, 14 insertions, 72 deletions

diff --git a/src/mainboard/emulation/qemu-armv7/Kconfig b/src/mainboard/emulation/qemu-armv7/Kconfig
index fc770cf27d..73b2d5dede 100644
--- a/src/mainboard/emulation/qemu-armv7/Kconfig
+++ b/src/mainboard/emulation/qemu-armv7/Kconfig
@@ -53,4 +53,8 @@ config MAINBOARD_VENDOR
 	string
 	default "ARM Ltd."
 
+config DRAM_SIZE_MB
+	int
+	default 1024
+
 endif #  BOARD_EMULATION_QEMU_ARMV7
diff --git a/src/mainboard/emulation/qemu-armv7/cbmem.c b/src/mainboard/emulation/qemu-armv7/cbmem.c
index 927bd42d54..542e08d05e 100644
--- a/src/mainboard/emulation/qemu-armv7/cbmem.c
+++ b/src/mainboard/emulation/qemu-armv7/cbmem.c
@@ -11,55 +11,11 @@
  * GNU General Public License for more details.
  */
 
-#include <stddef.h>
 #include <cbmem.h>
 #include <symbols.h>
-#include <device/mmio.h>
-#include "mainboard.h"
-
-#define PATTERN1 0x55
-#define PATTERN2 0xaa
-
-/* Returns 1 if mebibyte mb is present and 0 otherwise.  */
-static int probe_mb(int mb)
-{
-	char *ptr = (char *) 0x60000000 + (mb << 20) + 0xfffff;
-	char old;
-	if (ptr < (char *) &_eprogram) {
-		/* Don't probe below _end to avoid accidentally clobering
-		   oneself.  */
-		return 1;
-	}
-
-	old = read8(ptr);
-	write8(ptr, PATTERN1);
-	if (read8(ptr) != PATTERN1)
-		return 0;
-	write8(ptr, PATTERN2);
-	if (read8(ptr) != PATTERN2)
-		return 0;
-	write8(ptr, old);
-	return 1;
-}
-
-int probe_ramsize(void)
-{
-	int i;
-	int discovered = 0;
-	static int saved_result;
-	if (saved_result)
-		return saved_result;
-	/* Compact binary search.  */
-	/* 1 GiB is the largest supported RAM by this machine.  */
-	for (i = 9; i >= 0; i--)
-		if (probe_mb(discovered | (1 << i)))
-			discovered |= (1 << i);
-	discovered++;
-	saved_result = discovered;
-	return discovered;
-}
+#include <ramdetect.h>
 
 void *cbmem_top(void)
 {
-	return _dram + (probe_ramsize() << 20);
+	return _dram + (probe_ramsize((uintptr_t)_dram, CONFIG_DRAM_SIZE_MB) * MiB);
 }
diff --git a/src/mainboard/emulation/qemu-armv7/mainboard.c b/src/mainboard/emulation/qemu-armv7/mainboard.c
index cc14dd8e7b..338cff9321 100644
--- a/src/mainboard/emulation/qemu-armv7/mainboard.c
+++ b/src/mainboard/emulation/qemu-armv7/mainboard.c
@@ -18,9 +18,10 @@
 #include <device/device.h>
 #include <cbmem.h>
 #include <halt.h>
-#include "mainboard.h"
 #include <edid.h>
 #include <device/mmio.h>
+#include <ramdetect.h>
+#include <symbols.h>
 
 static void init_gfx(void)
 {
@@ -57,7 +58,7 @@ static void mainboard_enable(struct device *dev)
 		halt();
 	}
 
-	discovered = probe_ramsize();
+	discovered = probe_ramsize((uintptr_t)_dram, CONFIG_DRAM_SIZE_MB);
 	printk(BIOS_DEBUG, "%d MiB of RAM discovered\n", discovered);
 	ram_resource(dev, 0, 0x60000000 >> 10, discovered << 10);
 	cbmem_recovery(0);
diff --git a/src/mainboard/emulation/qemu-armv7/mainboard.h b/src/mainboard/emulation/qemu-armv7/mainboard.h
deleted file mode 100644
index 87fa3beee6..0000000000
--- a/src/mainboard/emulation/qemu-armv7/mainboard.h
+++ /dev/null
@@ -1,23 +0,0 @@
-/*
- * This file is part of the coreboot project.
- *
- * Copyright (C) 2016 Vladimir Serbinenko <phcoder@gmail.com>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; version 2 or, at your option, any later
- * version of the License.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- */
-
-#ifndef QEMU_ARMV7_MAINBOARD_H
-#define QEMU_ARMV7_MAINBOARD_H
-
-/* Returns RAM size in mebibytes.  */
-int probe_ramsize(void);
-
-#endif
diff --git a/src/mainboard/emulation/qemu-riscv/mainboard.c b/src/mainboard/emulation/qemu-riscv/mainboard.c
index 4b428aa486..02356aa70e 100644
--- a/src/mainboard/emulation/qemu-riscv/mainboard.c
+++ b/src/mainboard/emulation/qemu-riscv/mainboard.c
@@ -17,15 +17,19 @@
 #include <device/device.h>
 #include <cbmem.h>
 #include <symbols.h>
+#include <ramdetect.h>
 
 static void mainboard_enable(struct device *dev)
 {
+	size_t dram_mb_detected;
 
 	if (!dev) {
 		die("No dev0; die\n");
 	}
 
-	ram_resource(dev, 0, (uintptr_t)_dram / KiB, CONFIG_DRAM_SIZE_MB * KiB);
+	dram_mb_detected = probe_ramsize((uintptr_t)_dram, CONFIG_DRAM_SIZE_MB);
+	ram_resource(dev, 0, (uintptr_t)_dram / KiB, dram_mb_detected / KiB);
+
 	cbmem_recovery(0);
 }