EFS2: Implement Early Firmware Selection ver.2

EFS v1 allowed Chromeboxes to verify RW without AP. EFS v2 will bring
the benefts to Chromebooks, which are:

- Reduce RO dependency and presence. Allow more code to be updated
  in the fields.
- Remove jumptag and workarounds needed for late sysjump.

Major imporvements over v1 are:

- No A/B slot required.
- No signature in RW or public key in RO.
- Rollback-attack protection.
- Verifies only RW being used instead of whole RW section.

For battery-equipped devices, additional benefts are:

- Immediate boot on drained battery.
- Support recovery mode regardless of battery condition.
- Faster charge in S5/G3.

EC-Cr50 communication is based on the shared UART (go/ec-cr50-comm).
EFS2 is documented in go/ec-efs2.

Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>

BUG=chromium:1045217,chromium:141143112
BRANCH=none
TEST=Boot Helios in NORMAL/NO_BOOT/NO_BOOT_RECOVERY/RECOVERY mode.
TEST=Wake up EC from hibernate.
TEST=Make EC assert PACKET_MODE to wake up Cr50 from deepsleep.

Change-Id: I98a4fe1ecc59d106810a75daec3c424f953ff880
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2015357
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>
Commit-Queue: Daisuke Nojiri <dnojiri@chromium.org>
Tested-by: Daisuke Nojiri <dnojiri@chromium.org>
Auto-Submit: Daisuke Nojiri <dnojiri@chromium.org>

1 files changed, 116 insertions, 0 deletions

diff --git a/include/vboot.h b/include/vboot.h
index 776cc16441..771aeda599 100644
--- a/include/vboot.h
+++ b/include/vboot.h
@@ -3,9 +3,15 @@
  * found in the LICENSE file.
  */
 
+#ifndef __CROS_EC_INCLUDE_VBOOT_H
+#define __CROS_EC_INCLUDE_VBOOT_H
+
 #include "common.h"
 #include "vb21_struct.h"
 #include "rsa.h"
+#include "sha256.h"
+#include "stdbool.h"
+#include "timer.h"
 
 /**
  * Validate key contents.
@@ -66,3 +72,113 @@ void vboot_main(void);
  * @return 1: need PD communication. 0: PD communication is not needed.
  */
 int vboot_need_pd_comm(void);
+
+/**
+ * Callback for boards to notify users of vboot error when no display is
+ * available.
+ *
+ * Typically this happens when a Chromebox is booting on a Type-C adapter and
+ * EFS failed.
+ */
+__override_proto void show_critical_error(void);
+
+/**
+ * Callback for boards to notify the user of power shortage.
+ */
+__override_proto void show_power_shortage(void);
+
+/**
+ * Interrupt handler for packet mode entry.
+ *
+ * @param signal	GPIO id for packet mode interrupt pin.
+ */
+void packet_mode_interrupt(enum gpio_signal signal);
+
+/* Maximum number of times EC retries packet transmission before giving up. */
+#define CR50_COMM_MAX_RETRY	5
+
+/* EC's timeout for packet transmission to Cr50. */
+#define CR50_COMM_TIMEOUT	(50 * MSEC)
+
+/* Preamble character repeated before the packet header starts. */
+#define CR50_COMM_PREAMBLE	0xec
+
+/* Magic characters used to identify ec-cr50-comm packets */
+#define CR50_PACKET_MAGIC	0x4345	/* 'EC' in little endian */
+
+/* version of struct cr50_comm_request */
+#define CR50_COMM_PACKET_VERSION	(0 << 4 | 0 << 0)	/* 0.0 */
+
+/**
+ * EC-Cr50 data frame looks like the following:
+ *
+ *   [preamble][header][payload]
+ *
+ * preamble: 0xec ...
+ * header: struct cr50_comm_request
+ * payload: data[]
+ */
+struct cr50_comm_request {
+	/* Header */
+	uint16_t magic;		/* CR50_PACKET_MAGIC */
+	uint8_t struct_version;	/* version of this struct msb:lsb=major:minor */
+	uint8_t crc;		/* checksum computed from all bytes after crc */
+	uint16_t type;		/* CR50_CMD_* */
+	uint8_t size;		/* Payload size. Be easy on Cr50 buffer. */
+	/* Payload */
+	uint8_t data[];
+} __packed;
+
+struct cr50_comm_response {
+	uint16_t error;
+} __packed;
+
+#define CR50_COMM_MAX_REQUEST_SIZE	(sizeof(struct cr50_comm_request) \
+					 + UINT8_MAX)
+#define CR50_UART_RX_BUFFER_SIZE	32	/* TODO: Get from Cr50 header */
+
+/* commands */
+enum cr50_comm_cmd {
+	CR50_COMM_CMD_HELLO =		0x0000,
+	CR50_COMM_CMD_SET_BOOT_MODE =	0x0001,
+	CR50_COMM_CMD_VERIFY_HASH =	0x0002,
+	CR50_COMM_CMD_LIMIT =		0xffff,
+} __packed;
+BUILD_ASSERT(sizeof(enum cr50_comm_cmd) == sizeof(uint16_t));
+
+#define CR50_COMM_ERR_PREFIX		0xec
+
+/* return code */
+enum cr50_comm_err {
+	CR50_COMM_SUCCESS =		0xec00,
+	CR50_COMM_ERR_UNKNOWN =		0xec01,
+	CR50_COMM_ERR_MAGIC =		0xec02,
+	CR50_COMM_ERR_CRC =		0xec03,
+	CR50_COMM_ERR_SIZE =		0xec04,
+	CR50_COMM_ERR_TIMEOUT =		0xec05,	/* Generated by EC */
+	CR50_COMM_ERR_BAD_PAYLOAD =	0xec06,
+	CR50_COMM_ERR_UNDEFINED_CMD =	0xec07,
+	CR50_COMM_ERR_STRUCT_VERSION =	0xec08,
+} __packed;
+BUILD_ASSERT(sizeof(enum cr50_comm_err) == sizeof(uint16_t));
+
+/*
+ * BIT(1) : NO_BOOT flag
+ * BIT(0) : RECOVERY flag
+ */
+enum boot_mode {
+	BOOT_MODE_NORMAL           = 0x00,
+	BOOT_MODE_NO_BOOT          = 0x01,
+} __packed;
+BUILD_ASSERT(sizeof(enum boot_mode) == sizeof(uint8_t));
+
+/**
+ * Indicate PD is allowed (in RO) by vboot or not.
+ *
+ * Overridden by each EFS implementation (EFS1 and EFS2) not by boards.
+ *
+ * @return true - allowed. false - disallowed.
+ */
+__override_proto bool vboot_allow_usb_pd(void);
+
+#endif  /* __CROS_EC_INCLUDE_VBOOT_H */