Add persistent storage for emulator

This is needed for non-volatile register emulation. Also, this can be
used to implement system jump or reset flags.

BUG=chrome-os-partner:19235
TEST=Run utils test. Check persistent storage file exists.
BRANCH=None

Change-Id: I699f95718ef6f5de6c3bbb4e37619ee015fb6c4a
Signed-off-by: Vic Yang <victoryang@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/50313
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

5 files changed, 99 insertions, 1 deletions

diff --git a/chip/host/build.mk b/chip/host/build.mk
index ddcbefdb0b..110daefb8b 100644
--- a/chip/host/build.mk
+++ b/chip/host/build.mk
@@ -8,5 +8,5 @@
 
 CORE:=host
 
-chip-y=system.o gpio.o uart.o
+chip-y=system.o gpio.o uart.o persistence.o
 chip-$(HAS_TASK_KEYSCAN)+=keyboard_raw.o
diff --git a/chip/host/persistence.c b/chip/host/persistence.c
new file mode 100644
index 0000000000..bf3ce01788
--- /dev/null
+++ b/chip/host/persistence.c
@@ -0,0 +1,42 @@
+/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/* Persistence module for emulator */
+
+#include <unistd.h>
+#include <stdio.h>
+#include <string.h>
+
+#define BUF_SIZE 1024
+
+static void get_storage_path(char *out)
+{
+	char buf[BUF_SIZE];
+
+	readlink("/proc/self/exe", buf, BUF_SIZE);
+	if (snprintf(out, BUF_SIZE, "%s_persist", buf) >= BUF_SIZE)
+		out[BUF_SIZE - 1] = '\0';
+}
+
+FILE *get_persistent_storage(const char *tag, const char *mode)
+{
+	char buf[BUF_SIZE];
+	char path[BUF_SIZE];
+
+	/*
+	 * The persistent storage with tag 'foo' for test 'bar' would
+	 * be named 'bar_persist_foo'
+	 */
+	get_storage_path(buf);
+	if (snprintf(path, BUF_SIZE, "%s_%s", buf, tag) >= BUF_SIZE)
+		path[BUF_SIZE - 1] = '\0';
+
+	return fopen(path, mode);
+}
+
+void release_persistent_storage(FILE *ps)
+{
+	fclose(ps);
+}
diff --git a/chip/host/persistence.h b/chip/host/persistence.h
new file mode 100644
index 0000000000..37dbc5707a
--- /dev/null
+++ b/chip/host/persistence.h
@@ -0,0 +1,17 @@
+/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+/* Persistence module for emulator */
+
+#ifndef _PERSISTENCE_H
+#define _PERSISTENCE_H
+
+#include <stdio.h>
+
+FILE *get_persistent_storage(const char *tag, const char *mode);
+
+void release_persistent_storage(FILE *ps);
+
+#endif /* _PERSISTENCE_H */
diff --git a/chip/host/system.c b/chip/host/system.c
index 50da8db9c0..c290f9ef69 100644
--- a/chip/host/system.c
+++ b/chip/host/system.c
@@ -9,6 +9,7 @@
 
 #include "host_test.h"
 #include "system.h"
+#include "persistence.h"
 
 #define SHARED_MEM_SIZE 512 /* bytes */
 char __shared_mem_buf[SHARED_MEM_SIZE];
@@ -63,6 +64,34 @@ int system_set_vbnvcontext(const uint8_t *block)
 	return EC_ERROR_UNIMPLEMENTED;
 }
 
+int system_set_scratchpad(uint32_t value)
+{
+	FILE *f = get_persistent_storage("scratchpad", "w");
+
+	fprintf(f, "%lu", value);
+	release_persistent_storage(f);
+
+	return EC_SUCCESS;
+}
+
+uint32_t system_get_scratchpad(void)
+{
+	FILE *f = get_persistent_storage("scratchpad", "r");
+	uint32_t value;
+	int success;
+
+	if (f == NULL)
+		return 0;
+
+	success = fscanf(f, "%lu", &value);
+	release_persistent_storage(f);
+
+	if (success)
+		return value;
+	else
+		return 0;
+}
+
 int system_usable_ram_end(void)
 {
 	return (int)(__shared_mem_buf + SHARED_MEM_SIZE);
diff --git a/test/utils.c b/test/utils.c
index 559e8a0d94..81fe2ef072 100644
--- a/test/utils.c
+++ b/test/utils.c
@@ -8,6 +8,7 @@
 #include "common.h"
 #include "console.h"
 #include "shared_mem.h"
+#include "system.h"
 #include "timer.h"
 #include "util.h"
 
@@ -100,6 +101,14 @@ static int test_shared_mem(void)
 	return EC_SUCCESS;
 }
 
+static int test_scratchpad(void)
+{
+	system_set_scratchpad(0xfeedfeed);
+	TEST_ASSERT(system_get_scratchpad() == 0xfeedfeed);
+
+	return EC_SUCCESS;
+}
+
 void run_test(void)
 {
 	error_count = 0;
@@ -110,6 +119,7 @@ void run_test(void)
 	RUN_TEST(test_atoi);
 	RUN_TEST(test_uint64divmod);
 	RUN_TEST(test_shared_mem);
+	RUN_TEST(test_scratchpad);
 
 	if (error_count)
 		ccprintf("Failed %d tests!\n", error_count);