x86: Add a new API for e820

The existing mechanism is pretty painful as it requires manual
calculations for anything but a trivial setup.

Add a new API for adding e820 entries.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/x86/include/asm/e820.h

@@ -3,6 +3,8 @@
 
 #define E820MAX		128	/* number of entries in E820MAP */
 
+#ifdef __ASSEMBLY__
+
 #define E820_RAM	1
 #define E820_RESERVED	2
 #define E820_ACPI	3
@@ -10,9 +12,21 @@
 #define E820_UNUSABLE	5
 #define E820_COUNT	6	/* Number of types */
 
-#ifndef __ASSEMBLY__
+#else
+
 #include <linux/types.h>
 
+/* Available e820 memory-region types */
+enum e820_type {
+	E820_RAM	= 1,
+	E820_RESERVED,
+	E820_ACPI,
+	E820_NVS,
+	E820_UNUSABLE,
+
+	E820_COUNT,
+};
+
 struct e820_entry {
 	__u64 addr;	/* start of memory segment */
 	__u64 size;	/* size of memory segment */
@@ -22,10 +36,81 @@ struct e820_entry {
 #define ISA_START_ADDRESS	0xa0000
 #define ISA_END_ADDRESS		0x100000
 
+/**
+ * Context to use for e820_add()
+ *
+ * @entries: Table being filled in
+ * @addr: Current address we are up to
+ * @count: Number of entries added to @entries so far
+ * @max_entries: Maximum number of entries allowed
+ */
+struct e820_ctx {
+	struct e820_entry *entries;
+	u64 addr;
+	int count;
+	int max_entries;
+};
+
+/**
+ * e820_init() - Start setting up an e820 table
+ *
+ * @ctx: Context to set up
+ * @entries: Place to put entries
+ * @max_entries: Maximum size of @entries
+ */
+void e820_init(struct e820_ctx *ctx, struct e820_entry *entries,
+	       int max_entries);
+
+/**
+ * e820_add() - Add an entry to the table
+ *
+ * @ctx: Context
+ * @type: Type of entry
+ * @addr: Start address of entry
+ * @size Size of entry
+ */
+void e820_add(struct e820_ctx *ctx, enum e820_type type, u64 addr, u64 size);
+
+/**
+ * e820_to_addr() - Add an entry that covers the space up to a given address
+ *
+ * @ctx: Context
+ * @type: Type of entry
+ * @end_addr: Address where the entry should finish
+ */
+void e820_to_addr(struct e820_ctx *ctx, enum e820_type type, u64 end_addr);
+
+/**
+ * e820_next() - Add an entry that carries on from the last one
+ *
+ * @ctx: Context
+ * @type: Type of entry
+ * @size Size of entry
+ */
+void e820_next(struct e820_ctx *ctx, enum e820_type type, u64 size);
+
+/**
+ * e820_finish() - Finish the table
+ *
+ * Checks the table is not too large, panics if so
+ *
+ * @ctx: Context
+ * Returns: Number of entries
+ */
+int e820_finish(struct e820_ctx *ctx);
+
 /* Implementation-defined function to install an e820 map */
 unsigned int install_e820_map(unsigned int max_entries,
 			      struct e820_entry *);
 
+/**
+ * e820_dump() - Dump the e820 table
+ *
+ * @entries: Pointer to start of table
+ * @count: Number of entries in the table
+ */
+void e820_dump(struct e820_entry *entries, uint count);
+
 /**
  * cb_install_e820_map() - Install e820 map provided by coreboot sysinfo
  *

arch/x86/lib/e820.c

@@ -3,8 +3,11 @@
  * Copyright (C) 2015, Bin Meng <bmeng.cn@gmail.com>
  */
 
+#define LOG_CATEGORY	LOGC_ARCH
+
 #include <efi_loader.h>
 #include <lmb.h>
+#include <log.h>
 #include <asm/e820.h>
 #include <asm/global_data.h>
 
@@ -60,6 +63,50 @@ __weak unsigned int install_e820_map(unsigned int max_entries,
 	return 4;
 }
 
+void e820_init(struct e820_ctx *ctx, struct e820_entry *entries,
+	       int max_entries)
+{
+	memset(ctx, '\0', sizeof(*ctx));
+	ctx->entries = entries;
+	ctx->max_entries = max_entries;
+}
+
+void e820_add(struct e820_ctx *ctx, enum e820_type type, u64 addr, u64 size)
+{
+	struct e820_entry *entry = &ctx->entries[ctx->count++];
+
+	if (ctx->count <= ctx->max_entries) {
+		entry->addr = addr;
+		entry->size = size;
+		entry->type = type;
+	}
+	ctx->addr = addr + size;
+}
+
+void e820_next(struct e820_ctx *ctx, enum e820_type type, u64 size)
+{
+	e820_add(ctx, type, ctx->addr, size);
+}
+
+void e820_to_addr(struct e820_ctx *ctx, enum e820_type type, u64 addr)
+{
+	e820_next(ctx, type, addr - ctx->addr);
+}
+
+int e820_finish(struct e820_ctx *ctx)
+{
+	if (ctx->count > ctx->max_entries) {
+		printf("e820 has %d entries but room for only %d\n", ctx->count,
+		       ctx->max_entries);
+		panic("e820 table too large");
+	}
+	log_debug("e820 map installed, n=%d\n", ctx->count);
+	if (_DEBUG)
+		e820_dump(ctx->entries, ctx->count);
+
+	return ctx->count;
+}
+
 #if CONFIG_IS_ENABLED(EFI_LOADER)
 void efi_add_known_memory(void)
 {