system: Add generic bbram read / write routines

Add generic routines to read or write a byte to battery-backed RAM, and
implement vbnvcontext get/set using these routines.

BUG=chrome-os-partner:62952
BRANCH=reef
TEST=On reef, with subsequent commit, run "cutoff" on the console,
reattach AC, and verify device successfully wakes. Also verify Rp is
dropped on console 'reboot' and F3 + power from RW.

Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Change-Id: I14691923f2e5198e901b6b5199e92c58c68cd18d
Reviewed-on: https://chromium-review.googlesource.com/444444
Commit-Ready: Shawn N <shawnn@chromium.org>
Tested-by: Shawn N <shawnn@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
(cherry picked from commit f0b564b4a031fdc974a98a13308a62a460ae4a69)
Reviewed-on: https://chromium-review.googlesource.com/446715

11 files changed, 182 insertions, 108 deletions

diff --git a/chip/g/system.c b/chip/g/system.c
index 85fcf63774..02ccb7eea7 100644
--- a/chip/g/system.c
+++ b/chip/g/system.c
@@ -171,12 +171,12 @@ const char *system_get_chip_revision(void)
 }
 
 /* TODO(crosbug.com/p/33822): Where can we store stuff persistently? */
-int system_get_vbnvcontext(uint8_t *block)
+int system_get_bbram(enum system_bbram_idx idx, uint8_t *value)
 {
 	return 0;
 }
 
-int system_set_vbnvcontext(const uint8_t *block)
+int system_set_bbram(enum system_bbram_idx idx, uint8_t value)
 {
 	return 0;
 }
diff --git a/chip/host/system.c b/chip/host/system.c
index 757d00fc51..26965c5d16 100644
--- a/chip/host/system.c
+++ b/chip/host/system.c
@@ -188,12 +188,12 @@ const char *system_get_chip_revision(void)
 	return "";
 }
 
-int system_get_vbnvcontext(uint8_t *block)
+int system_get_bbram(enum system_bbram_idx idx, uint8_t *value)
 {
 	return EC_ERROR_UNIMPLEMENTED;
 }
 
-int system_set_vbnvcontext(const uint8_t *block)
+int system_set_bbram(enum system_bbram_idx idx, uint8_t value)
 {
 	return EC_ERROR_UNIMPLEMENTED;
 }
diff --git a/chip/ish/system.c b/chip/ish/system.c
index 75f1d5a4a8..7110e85645 100644
--- a/chip/ish/system.c
+++ b/chip/ish/system.c
@@ -1,4 +1,4 @@
-/* Copyright (c) 2016 The Chromium OS Authors. All rights reserved.
+/* Copyright 2016 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.
  */
@@ -76,12 +76,12 @@ const char *system_get_chip_revision(void)
 	return buf;
 }
 
-int system_get_vbnvcontext(uint8_t *block)
+int system_get_bbram(enum system_bbram_idx idx, uint8_t *value)
 {
 	return EC_ERROR_UNIMPLEMENTED;
 }
 
-int system_set_vbnvcontext(const uint8_t *block)
+int system_set_bbram(enum system_bbram_idx idx, uint8_t value)
 {
 	return EC_ERROR_UNIMPLEMENTED;
 }
diff --git a/chip/it83xx/system.c b/chip/it83xx/system.c
index 32ab43231f..055c586cd8 100644
--- a/chip/it83xx/system.c
+++ b/chip/it83xx/system.c
@@ -226,25 +226,37 @@ const char *system_get_chip_revision(void)
 	return buf;
 }
 
-int system_get_vbnvcontext(uint8_t *block)
+static int bram_idx_lookup(enum system_bbram_idx idx)
 {
-	int i;
+	if (idx >= SYSTEM_BBRAM_IDX_VBNVBLOCK0 &&
+	    idx <= SYSTEM_BBRAM_IDX_VBNVBLOCK15)
+		return BRAM_IDX_NVCONTEXT +
+		       idx - SYSTEM_BBRAM_IDX_VBNVBLOCK0;
+	return -1;
+}
+
+int system_get_bbram(enum system_bbram_idx idx, uint8_t *value)
+{
+	int bram_idx = bram_idx_lookup(idx);
 
-	for (i = 0; i < EC_VBNV_BLOCK_SIZE; i++)
-		block[i] = IT83XX_BRAM_BANK0((BRAM_IDX_NVCONTEXT + i));
+	if (bram_idx < 0)
+		return EC_ERROR_INVAL;
 
+	*value = IT83XX_BRAM_BANK0(bram_idx);
 	return EC_SUCCESS;
 }
 
-int system_set_vbnvcontext(const uint8_t *block)
+int system_set_bbram(enum system_bbram_idx idx, uint8_t value)
 {
-	int i;
+	int bram_idx = bram_idx_lookup(idx);
 
-	for (i = 0; i < EC_VBNV_BLOCK_SIZE; i++)
-		IT83XX_BRAM_BANK0((BRAM_IDX_NVCONTEXT + i)) = block[i];
+	if (bram_idx < 0)
+		return EC_ERROR_INVAL;
 
+	IT83XX_BRAM_BANK0(bram_idx) = value;
 	return EC_SUCCESS;
 }
+
 #define BRAM_NVCONTEXT_SIZE (BRAM_IDX_NVCONTEXT_END - BRAM_IDX_NVCONTEXT + 1)
 BUILD_ASSERT(EC_VBNV_BLOCK_SIZE <= BRAM_NVCONTEXT_SIZE);
 
diff --git a/chip/lm4/system.c b/chip/lm4/system.c
index cb1cf8cef0..684b520dae 100644
--- a/chip/lm4/system.c
+++ b/chip/lm4/system.c
@@ -600,12 +600,12 @@ const char *system_get_chip_name(void)
 	}
 }
 
-int system_get_vbnvcontext(uint8_t *block)
+int system_get_bbram(enum system_bbram_idx idx, uint8_t *value)
 {
 	return EC_ERROR_UNIMPLEMENTED;
 }
 
-int system_set_vbnvcontext(const uint8_t *block)
+int system_set_bbram(enum system_bbram_idx idx, uint8_t value)
 {
 	return EC_ERROR_UNIMPLEMENTED;
 }
diff --git a/chip/mec1322/system.c b/chip/mec1322/system.c
index 26d89c10e3..54ff2f45c8 100644
--- a/chip/mec1322/system.c
+++ b/chip/mec1322/system.c
@@ -23,7 +23,7 @@
 /* Indices for hibernate data registers (RAM backed by VBAT) */
 enum hibdata_index {
 	HIBDATA_INDEX_SCRATCHPAD = 0,    /* General-purpose scratchpad */
-	HIBDATA_INDEX_SAVED_RESET_FLAGS  /* Saved reset flags */
+	HIBDATA_INDEX_SAVED_RESET_FLAGS, /* Saved reset flags */
 };
 
 static void check_reset_cause(void)
@@ -166,14 +166,30 @@ const char *system_get_chip_revision(void)
 	return buf;
 }
 
-int system_get_vbnvcontext(uint8_t *block)
+int system_get_bbram(enum system_bbram_idx idx, uint8_t *value)
 {
-	return EC_ERROR_UNIMPLEMENTED;
+	enum hibdata_index hibdata;
+
+	switch (idx) {
+	default:
+		return EC_ERROR_UNIMPLEMENTED;
+	}
+
+	*value = MEC1322_VBAT_RAM(hibdata);
+	return EC_SUCCESS;
 }
 
-int system_set_vbnvcontext(const uint8_t *block)
+int system_set_bbram(enum system_bbram_idx idx, uint8_t value)
 {
-	return EC_ERROR_UNIMPLEMENTED;
+	enum hibdata_index hibdata;
+
+	switch (idx) {
+	default:
+		return EC_ERROR_UNIMPLEMENTED;
+	}
+
+	MEC1322_VBAT_RAM(hibdata) = value;
+	return EC_SUCCESS;
 }
 
 int system_set_scratchpad(uint32_t value)
diff --git a/chip/npcx/system.c b/chip/npcx/system.c
index 2d11217f5b..a747cbf866 100644
--- a/chip/npcx/system.c
+++ b/chip/npcx/system.c
@@ -6,21 +6,21 @@
 /* System module for Chrome EC : NPCX hardware specific implementation */
 
 #include "clock.h"
+#include "clock_chip.h"
 #include "common.h"
 #include "console.h"
 #include "cpu.h"
+#include "gpio.h"
+#include "hooks.h"
 #include "host_command.h"
+#include "hwtimer_chip.h"
 #include "registers.h"
+#include "rom_chip.h"
 #include "system.h"
-#include "hooks.h"
+#include "system_chip.h"
 #include "task.h"
 #include "timer.h"
 #include "util.h"
-#include "gpio.h"
-#include "hwtimer_chip.h"
-#include "system_chip.h"
-#include "clock_chip.h"
-#include "rom_chip.h"
 
 /* Flags for BBRM_DATA_INDEX_WAKE */
 #define HIBERNATE_WAKE_MTC        (1 << 0)  /* MTC alarm */
@@ -83,6 +83,13 @@ void system_watchdog_reset(void)
 	interrupt_enable();
 }
 
+/* Return true if index is stored as a single byte in bbram */
+static int bbram_is_byte_access(enum bbram_data_index index)
+{
+	return (index >= BBRM_DATA_INDEX_VBNVCNTXT &&
+		index <  BBRM_DATA_INDEX_RAMLOG);
+}
+
 /**
  * Read battery-backed ram (BBRAM) at specified index.
  *
@@ -91,8 +98,10 @@ void system_watchdog_reset(void)
 static uint32_t bbram_data_read(enum bbram_data_index index)
 {
 	uint32_t value = 0;
+	int bytes = bbram_is_byte_access(index) ? 1 : 4;
+
 	/* Check index */
-	if (index < 0 || index >= NPCX_BBRAM_SIZE)
+	if (index < 0 || index + bytes >= NPCX_BBRAM_SIZE)
 		return 0;
 
 	/* BBRAM is valid */
@@ -100,12 +109,14 @@ static uint32_t bbram_data_read(enum bbram_data_index index)
 		return 0;
 
 	/* Read BBRAM */
-	value += NPCX_BBRAM(index + 3);
-	value = value << 8;
-	value += NPCX_BBRAM(index + 2);
-	value = value << 8;
-	value += NPCX_BBRAM(index + 1);
-	value = value << 8;
+	if (bytes == 4) {
+		value += NPCX_BBRAM(index + 3);
+		value = value << 8;
+		value += NPCX_BBRAM(index + 2);
+		value = value << 8;
+		value += NPCX_BBRAM(index + 1);
+		value = value << 8;
+	}
 	value += NPCX_BBRAM(index);
 
 	return value;
@@ -118,6 +129,8 @@ static uint32_t bbram_data_read(enum bbram_data_index index)
  */
 static int bbram_data_write(enum bbram_data_index index, uint32_t value)
 {
+	int bytes = bbram_is_byte_access(index) ? 1 : 4;
+
 	/* Check index */
 	if (index < 0 || index >= NPCX_BBRAM_SIZE)
 		return EC_ERROR_INVAL;
@@ -127,15 +140,48 @@ static int bbram_data_write(enum bbram_data_index index, uint32_t value)
 		return EC_ERROR_INVAL;
 
 	/* Write BBRAM */
-	NPCX_BBRAM(index)     = value & 0xFF;
-	NPCX_BBRAM(index + 1) = (value >> 8)  & 0xFF;
-	NPCX_BBRAM(index + 2) = (value >> 16) & 0xFF;
-	NPCX_BBRAM(index + 3) = (value >> 24) & 0xFF;
+	NPCX_BBRAM(index) = value & 0xFF;
+	if (bytes == 4) {
+		NPCX_BBRAM(index + 1) = (value >> 8)  & 0xFF;
+		NPCX_BBRAM(index + 2) = (value >> 16) & 0xFF;
+		NPCX_BBRAM(index + 3) = (value >> 24) & 0xFF;
+	}
 
 	/* Wait for write-complete */
 	return EC_SUCCESS;
 }
 
+/* Map idx to a returned BBRM_DATA_INDEX_*, or return -1 on invalid idx */
+static int bbram_idx_lookup(enum system_bbram_idx idx)
+{
+	if (idx >= SYSTEM_BBRAM_IDX_VBNVBLOCK0 &&
+	    idx <= SYSTEM_BBRAM_IDX_VBNVBLOCK15)
+		return BBRM_DATA_INDEX_VBNVCNTXT +
+		       idx - SYSTEM_BBRAM_IDX_VBNVBLOCK0;
+	return -1;
+}
+
+int system_get_bbram(enum system_bbram_idx idx, uint8_t *value)
+{
+	int bbram_idx = bbram_idx_lookup(idx);
+
+	if (bbram_idx < 0)
+		return EC_ERROR_INVAL;
+
+	*value = bbram_data_read(bbram_idx);
+	return EC_SUCCESS;
+}
+
+int system_set_bbram(enum system_bbram_idx idx, uint8_t value)
+{
+	int bbram_idx = bbram_idx_lookup(idx);
+
+	if (bbram_idx < 0)
+		return EC_ERROR_INVAL;
+
+	return bbram_data_write(bbram_idx, value);
+}
+
 /* MTC functions */
 uint32_t system_get_rtc_sec(void)
 {
@@ -673,41 +719,6 @@ const char *system_get_chip_revision(void)
 BUILD_ASSERT(BBRM_DATA_INDEX_VBNVCNTXT + EC_VBNV_BLOCK_SIZE <= NPCX_BBRAM_SIZE);
 
 /**
- * Get/Set VbNvContext in non-volatile storage.  The block should be 16 bytes
- * long, which is the current size of VbNvContext block.
- *
- * @param block		Pointer to a buffer holding VbNvContext.
- * @return 0 on success, !0 on error.
- */
-int system_get_vbnvcontext(uint8_t *block)
-{
-	int i;
-
-	if (IS_BIT_SET(NPCX_BKUP_STS, NPCX_BKUP_STS_IBBR)) {
-		memset(block, 0, EC_VBNV_BLOCK_SIZE);
-		return EC_SUCCESS;
-	}
-
-	for (i = 0; i < EC_VBNV_BLOCK_SIZE; ++i)
-		block[i] = NPCX_BBRAM(BBRM_DATA_INDEX_VBNVCNTXT + i);
-
-	return EC_SUCCESS;
-}
-
-int system_set_vbnvcontext(const uint8_t *block)
-{
-	int i;
-
-	if (IS_BIT_SET(NPCX_BKUP_STS, NPCX_BKUP_STS_IBBR))
-		return EC_ERROR_INVAL;
-
-	for (i = 0; i < EC_VBNV_BLOCK_SIZE; i++)
-		NPCX_BBRAM(BBRM_DATA_INDEX_VBNVCNTXT + i) = block[i];
-
-	return EC_SUCCESS;
-}
-
-/**
  * Set a scratchpad register to the specified value.
  *
  * The scratchpad register must maintain its contents across a
diff --git a/chip/nrf51/system.c b/chip/nrf51/system.c
index 94c36202e4..61bd2311a8 100644
--- a/chip/nrf51/system.c
+++ b/chip/nrf51/system.c
@@ -107,13 +107,13 @@ void system_reset(int flags)
 		;
 }
 
-int system_get_vbnvcontext(uint8_t *block)
+int system_get_bbram(enum system_bbram_idx idx, uint8_t *value)
 {
 	CPRINTS("TODO: implement %s()", __func__);
 	return EC_ERROR_UNIMPLEMENTED;
 }
 
-int system_set_vbnvcontext(const uint8_t *block)
+int system_set_bbram(enum system_bbram_idx idx, uint8_t value)
 {
 	CPRINTS("TODO: implement %s()", __func__);
 	return EC_ERROR_UNIMPLEMENTED;
diff --git a/chip/stm32/system.c b/chip/stm32/system.c
index 605f095f95..466ebc50c9 100644
--- a/chip/stm32/system.c
+++ b/chip/stm32/system.c
@@ -336,36 +336,47 @@ const char *system_get_chip_revision(void)
 	return "";
 }
 
-int system_get_vbnvcontext(uint8_t *block)
+static int bkpdata_index_lookup(enum system_bbram_idx idx, int *msb)
 {
-	enum bkpdata_index i;
-	uint16_t value;
-
-	for (i = BKPDATA_INDEX_VBNV_CONTEXT0;
-			i <= BKPDATA_INDEX_VBNV_CONTEXT7; i++) {
-		value = bkpdata_read(i);
-		*block++ = (uint8_t)(value & 0xff);
-		*block++ = (uint8_t)(value >> 8);
+	*msb = 0;
+
+	if (idx >= SYSTEM_BBRAM_IDX_VBNVBLOCK0 &&
+	    idx <= SYSTEM_BBRAM_IDX_VBNVBLOCK15) {
+		*msb = (idx - SYSTEM_BBRAM_IDX_VBNVBLOCK0) % 2;
+		return BKPDATA_INDEX_VBNV_CONTEXT0 +
+		       (idx - SYSTEM_BBRAM_IDX_VBNVBLOCK0) / 2;
 	}
+	return -1;
+}
+
+int system_get_bbram(enum system_bbram_idx idx, uint8_t *value)
+{
+	int msb = 0;
+	int bkpdata_index = bkpdata_index_lookup(idx, &msb);
+
+	if (bkpdata_index < 0)
+		return EC_ERROR_INVAL;
 
+	*value = (bkpdata_read(bkpdata_index) >> (8 * msb)) & 0xff;
 	return EC_SUCCESS;
 }
 
-int system_set_vbnvcontext(const uint8_t *block)
+int system_set_bbram(enum system_bbram_idx idx, uint8_t value)
 {
-	enum bkpdata_index i;
-	uint16_t value;
-	int err;
-
-	for (i = BKPDATA_INDEX_VBNV_CONTEXT0;
-			i <= BKPDATA_INDEX_VBNV_CONTEXT7; i++) {
-		value = *block++;
-		value |= ((uint16_t)*block++) << 8;
-		err = bkpdata_write(i, value);
-		if (err)
-			return err;
-	}
+	uint16_t read;
+	int msb = 0;
+	int bkpdata_index = bkpdata_index_lookup(idx, &msb);
+
+	if (bkpdata_index < 0)
+		return EC_ERROR_INVAL;
+
+	read = bkpdata_read(bkpdata_index);
+	if (msb)
+		read = (read & 0xff) | (value << 8);
+	else
+		read = (read & 0xff00) | value;
 
+	bkpdata_write(bkpdata_index, read);
 	return EC_SUCCESS;
 }
 
diff --git a/common/system.c b/common/system.c
index 5baea57c95..963ce2ff52 100644
--- a/common/system.c
+++ b/common/system.c
@@ -1227,17 +1227,22 @@ int host_command_vbnvcontext(struct host_cmd_handler_args *args)
 {
 	const struct ec_params_vbnvcontext *p = args->params;
 	struct ec_response_vbnvcontext *r;
+	int i;
 
 	switch (p->op) {
 	case EC_VBNV_CONTEXT_OP_READ:
 		r = args->response;
-		if (system_get_vbnvcontext(r->block))
-			return EC_RES_ERROR;
+		for (i = 0; i < EC_VBNV_BLOCK_SIZE; ++i)
+			if (system_get_bbram(SYSTEM_BBRAM_IDX_VBNVBLOCK0 + i,
+					     r->block + i))
+				return EC_RES_ERROR;
 		args->response_size = sizeof(*r);
 		break;
 	case EC_VBNV_CONTEXT_OP_WRITE:
-		if (system_set_vbnvcontext(p->block))
-			return EC_RES_ERROR;
+		for (i = 0; i < EC_VBNV_BLOCK_SIZE; ++i)
+			if (system_set_bbram(SYSTEM_BBRAM_IDX_VBNVBLOCK0 + i,
+					     p->block[i]))
+				return EC_RES_ERROR;
 		break;
 	default:
 		return EC_RES_ERROR;
diff --git a/include/system.h b/include/system.h
index fa16846303..76db18053c 100644
--- a/include/system.h
+++ b/include/system.h
@@ -263,15 +263,34 @@ const char *system_get_chip_vendor(void);
 const char *system_get_chip_name(void);
 const char *system_get_chip_revision(void);
 
+/*
+ * Common bbram entries. Chips don't necessarily need to implement
+ * all of these, error will be returned from system_get/set_bbram if
+ * not implemented.
+ */
+enum system_bbram_idx {
+	/*
+	 * TODO(crbug.com/693210): Consider boards without vbnvcontext
+	 * host command.
+	 */
+	SYSTEM_BBRAM_IDX_VBNVBLOCK0 = 0,
+	/*
+	 * ...
+	 * 16 total bytes of VB NVRAM.
+	 * ...
+	 */
+	SYSTEM_BBRAM_IDX_VBNVBLOCK15 = 15,
+};
+
 /**
- * Get/Set VbNvContext in non-volatile storage.  The block should be 16 bytes
- * long, which is the current size of VbNvContext block.
+ * Get/Set byte in battery-backed storage.
  *
- * @param block		Pointer to a buffer holding VbNvContext.
- * @return 0 on success, !0 on error.
+ * @param idx		bbram byte to get / set.
+ * @param value		byte to read / write from / to bbram.
+ * @return		0 on success, !0 on error.
  */
-int system_get_vbnvcontext(uint8_t *block);
-int system_set_vbnvcontext(const uint8_t *block);
+int system_get_bbram(enum system_bbram_idx idx, uint8_t *value);
+int system_set_bbram(enum system_bbram_idx idx, uint8_t value);
 
 /**
  * Put the EC in hibernate (lowest EC power state).