servo_micro: add programmable serial number

This change provides a console command for setting,
and loading a usb serial number from flash. This
feature adds CONFIG_USB_SERIALNO, and currently only
has a useful implementation when PSTATE is present.

BUG=chromium:571477
TEST=serialno set abcdef; serialno load; reboot
BRANCH=none

Change-Id: I3b24cfa2d52d54118bc3fd54b276e3d95412d245
Signed-off-by: Nick Sanders <nsanders@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/337359
Reviewed-by: Randall Spangler <rspangler@chromium.org>

7 files changed, 297 insertions, 29 deletions

diff --git a/board/servo_micro/board.c b/board/servo_micro/board.c
index f22bda4342..5ee94f032b 100644
--- a/board/servo_micro/board.c
+++ b/board/servo_micro/board.c
@@ -154,12 +154,11 @@ USB_STREAM_CONFIG(usart4_usb,
 /******************************************************************************
  * Define the strings used in our USB descriptors.
  */
-
 const void *const usb_strings[] = {
 	[USB_STR_DESC]         = usb_string_desc,
 	[USB_STR_VENDOR]       = USB_STRING_DESC("Google Inc."),
 	[USB_STR_PRODUCT]      = USB_STRING_DESC("Servo Micro"),
-	[USB_STR_SERIALNO]     = USB_STRING_DESC("1234-a"),
+	[USB_STR_SERIALNO]     = 0,
 	[USB_STR_VERSION]      = USB_STRING_DESC(CROS_EC_VERSION32),
 	[USB_STR_USART4_STREAM_NAME]  = USB_STRING_DESC("Servo UART3"),
 	[USB_STR_CONSOLE_NAME] = USB_STRING_DESC("Servo EC Shell"),
@@ -169,7 +168,6 @@ const void *const usb_strings[] = {
 
 BUILD_ASSERT(ARRAY_SIZE(usb_strings) == USB_STR_COUNT);
 
-
 /******************************************************************************
  * Support SPI bridging over USB, this requires usb_spi_board_enable and
  * usb_spi_board_disable to be defined to enable and disable the SPI bridge.
diff --git a/board/servo_micro/board.h b/board/servo_micro/board.h
index 48f9368436..7efb2fc3dd 100644
--- a/board/servo_micro/board.h
+++ b/board/servo_micro/board.h
@@ -87,6 +87,9 @@
 
 #include "gpio_signal.h"
 
+#define CONFIG_USB_SERIALNO
+#define DEFAULT_SERIALNO "Uninitialized"
+
 /* USB string indexes */
 enum usb_strings {
 	USB_STR_DESC = 0,
diff --git a/chip/stm32/usb.c b/chip/stm32/usb.c
index ca82fbd4a4..85e2320642 100644
--- a/chip/stm32/usb.c
+++ b/chip/stm32/usb.c
@@ -7,6 +7,7 @@
 #include "common.h"
 #include "config.h"
 #include "console.h"
+#include "flash.h"
 #include "gpio.h"
 #include "hooks.h"
 #include "link_defs.h"
@@ -34,6 +35,12 @@
 #define CONFIG_USB_BCD_DEV 0x0100 /* 1.00 */
 #endif
 
+#ifndef CONFIG_USB_SERIALNO
+#define USB_STR_SERIALNO 0
+#else
+static int usb_load_serial(void);
+#endif
+
 /* USB Standard Device Descriptor */
 static const struct usb_device_descriptor dev_desc = {
 	.bLength = USB_DT_DEVICE_SIZE,
@@ -48,7 +55,7 @@ static const struct usb_device_descriptor dev_desc = {
 	.bcdDevice = CONFIG_USB_BCD_DEV,
 	.iManufacturer = USB_STR_VENDOR,
 	.iProduct = USB_STR_PRODUCT,
-	.iSerialNumber = 0,
+	.iSerialNumber = USB_STR_SERIALNO,
 	.bNumConfigurations = 1
 };
 
@@ -85,6 +92,8 @@ static int desc_left;
 /* pointer to descriptor data if any */
 static const uint8_t *desc_ptr;
 
+
+
 void usb_read_setup_packet(usb_uint *buffer, struct usb_setup_packet *packet)
 {
 	packet->bmRequestType = buffer[0] & 0xff;
@@ -137,7 +146,12 @@ static void ep0_rx(void)
 			if (idx >= USB_STR_COUNT)
 				/* The string does not exist : STALL */
 				goto unknown_req;
-			desc = usb_strings[idx];
+#ifdef CONFIG_USB_SERIALNO
+			if (idx == USB_STR_SERIALNO)
+				desc = (uint8_t *)usb_serialno_desc;
+			else
+#endif
+				desc = usb_strings[idx];
 			len = desc[0];
 			break;
 		case USB_DT_DEVICE_QUALIFIER: /* Get device qualifier desc */
@@ -307,6 +321,9 @@ void usb_init(void)
 	/* set interrupts mask : reset/correct tranfer/errors */
 	STM32_USB_CNTR = 0xe400;
 
+#ifdef CONFIG_USB_SERIALNO
+	usb_load_serial();
+#endif
 #ifndef CONFIG_USB_INHIBIT_CONNECT
 	usb_connect();
 #endif
@@ -402,3 +419,94 @@ void *memcpy_from_usbram(void *dest, const void *src, size_t n)
 
 	return dest;
 }
+
+#ifdef CONFIG_USB_SERIALNO
+/* This will be subbed into USB_STR_SERIALNO. */
+struct usb_string_desc *usb_serialno_desc =
+	USB_WR_STRING_DESC(DEFAULT_SERIALNO);
+
+/* Update serial number */
+static int usb_set_serial(const char *serialno)
+{
+	struct usb_string_desc *sd = usb_serialno_desc;
+	int i;
+
+	if (!serialno)
+		return EC_ERROR_INVAL;
+
+	/* Convert into unicode usb string desc. */
+	for (i = 0; i < USB_STRING_LEN; i++) {
+		sd->_data[i] = serialno[i];
+		if (serialno[i] == 0)
+			break;
+	}
+	/* Count wchars (w/o null terminator) plus size & type bytes. */
+	sd->_len = (i * 2) + 2;
+	sd->_type = USB_DT_STRING;
+
+	return EC_SUCCESS;
+}
+
+/* Retrieve serial number from pstate flash. */
+static int usb_load_serial(void)
+{
+	const char *serialno;
+	int rv;
+
+	serialno = flash_read_serial();
+	if (!serialno)
+		return EC_ERROR_ACCESS_DENIED;
+
+	rv = usb_set_serial(serialno);
+	return rv;
+}
+
+/* Save serial number into pstate region. */
+static int usb_save_serial(const char *serialno)
+{
+	int rv;
+
+	if (!serialno)
+		return EC_ERROR_INVAL;
+
+	/* Save this new serial number to flash. */
+	rv = flash_write_serial(serialno);
+	if (rv)
+		return rv;
+
+	/* Load this new serial number to memory. */
+	rv = usb_load_serial();
+	return rv;
+}
+
+static int command_serialno(int argc, char **argv)
+{
+	struct usb_string_desc *sd = usb_serialno_desc;
+	char buf[USB_STRING_LEN];
+	int rv = EC_SUCCESS;
+	int i;
+
+	if (argc != 1) {
+		if ((strcasecmp(argv[1], "set") == 0) &&
+		    (argc == 3)) {
+			ccprintf("Saving serial number\n");
+			rv = usb_save_serial(argv[2]);
+		} else if ((strcasecmp(argv[1], "load") == 0) &&
+			   (argc == 2)) {
+			ccprintf("Loading serial number\n");
+			rv = usb_load_serial();
+		} else
+			return EC_ERROR_INVAL;
+	}
+
+	for (i = 0; i < USB_STRING_LEN; i++)
+		buf[i] = sd->_data[i];
+	ccprintf("Serial number: %s\n", buf);
+	return rv;
+}
+
+DECLARE_CONSOLE_COMMAND(serialno, command_serialno,
+	"load/set [value]",
+	"Read and write USB serial number",
+	NULL);
+#endif
diff --git a/common/flash.c b/common/flash.c
index 7cd977d9e0..2bb1679197 100644
--- a/common/flash.c
+++ b/common/flash.c
@@ -35,17 +35,24 @@
 
 #ifdef CONFIG_FLASH_PSTATE_BANK
 /* Persistent protection state - emulates a SPI status register for flashrom */
-struct persist_state {
-	uint8_t version;            /* Version of this struct */
-	uint8_t flags;              /* Lock flags (PERSIST_FLAG_*) */
-	uint8_t reserved[2];        /* Reserved; set 0 */
-};
-
-#define PERSIST_STATE_VERSION 2  /* Expected persist_state.version */
+/* NOTE: It's not expected that RO and RW will support
+ * differing PSTATE versions. */
+#define PERSIST_STATE_VERSION 3  /* Expected persist_state.version */
+#define SERIALNO_MAX 30
 
 /* Flags for persist_state.flags */
 /* Protect persist state and RO firmware at boot */
 #define PERSIST_FLAG_PROTECT_RO 0x02
+#define PSTATE_VALID_FLAGS	(1 << 0)
+#define PSTATE_VALID_SERIALNO	(1 << 1)
+
+struct persist_state {
+	uint8_t version;            /* Version of this struct */
+	uint8_t flags;              /* Lock flags (PERSIST_FLAG_*) */
+	uint8_t valid_fields;       /* Flags for valid data. */
+	uint8_t reserved;           /* Reserved; set 0 */
+	uint8_t serialno[SERIALNO_MAX]; /* Serial number. */
+};
 
 #else /* !CONFIG_FLASH_PSTATE_BANK */
 
@@ -142,6 +149,7 @@ static uint32_t flash_read_pstate(void)
 		flash_physical_dataptr(CONFIG_FW_PSTATE_OFF);
 
 	if ((pstate->version == PERSIST_STATE_VERSION) &&
+	    (pstate->valid_fields & PSTATE_VALID_FLAGS) &&
 	    (pstate->flags & PERSIST_FLAG_PROTECT_RO)) {
 		/* Lock flag is known to be set */
 		return EC_FLASH_PROTECT_RO_AT_BOOT;
@@ -155,23 +163,33 @@ static uint32_t flash_read_pstate(void)
 }
 
 /**
- * Write persistent state from pstate, erasing if necessary.
+ * Read and return persistent serial number.
+ */
+static const char *flash_read_pstate_serial(void)
+{
+	const struct persist_state *pstate =
+		(const struct persist_state *)
+		flash_physical_dataptr(CONFIG_FW_PSTATE_OFF);
+
+	if ((pstate->version == PERSIST_STATE_VERSION) &&
+	    (pstate->valid_fields & PSTATE_VALID_SERIALNO)) {
+		return (const char *)(pstate->serialno);
+	}
+
+	return 0;
+}
+
+/**
+ * Write persistent state after erasing.
  *
- * @param flags		New flash write protect flags to set in pstate.
+ * @param pstate	New data to set in pstate. NOT memory mapped
+ *                      old pstate as it will be erased.
  * @return EC_SUCCESS, or nonzero if error.
  */
-static int flash_write_pstate(uint32_t flags)
+static int flash_write_pstate_data(struct persist_state *newpstate)
 {
-	struct persist_state pstate;
 	int rv;
 
-	/* Only check the flags we write to pstate */
-	flags &= EC_FLASH_PROTECT_RO_AT_BOOT;
-
-	/* Check if pstate has actually changed */
-	if (flags == flash_read_pstate())
-		return EC_SUCCESS;
-
 	/* Erase pstate */
 	rv = flash_physical_erase(CONFIG_FW_PSTATE_OFF,
 				  CONFIG_FW_PSTATE_SIZE);
@@ -184,15 +202,101 @@ static int flash_write_pstate(uint32_t flags)
 	 * it's protected.
 	 */
 
-	/* Write a new pstate */
-	memset(&pstate, 0, sizeof(pstate));
-	pstate.version = PERSIST_STATE_VERSION;
+	/* Write the updated pstate */
+	return flash_physical_write(CONFIG_FW_PSTATE_OFF, sizeof(*newpstate),
+				    (const char *)newpstate);
+}
+
+
+
+/**
+ * Validate and Init persistent state datastructure.
+ *
+ * @param pstate	A pstate data structure. Will be valid at complete.
+ * @return EC_SUCCESS, or nonzero if error.
+ */
+static int validate_pstate_struct(struct persist_state *pstate)
+{
+	if (pstate->version != PERSIST_STATE_VERSION) {
+		memset(pstate, 0, sizeof(*pstate));
+		pstate->version = PERSIST_STATE_VERSION;
+		pstate->valid_fields = 0;
+	}
+
+	return EC_SUCCESS;
+}
+
+/**
+ * Write persistent state from pstate, erasing if necessary.
+ *
+ * @param flags		New flash write protect flags to set in pstate.
+ * @return EC_SUCCESS, or nonzero if error.
+ */
+static int flash_write_pstate(uint32_t flags)
+{
+	struct persist_state newpstate;
+	const struct persist_state *pstate =
+		(const struct persist_state *)
+		flash_physical_dataptr(CONFIG_FW_PSTATE_OFF);
+
+	/* Only check the flags we write to pstate */
+	flags &= EC_FLASH_PROTECT_RO_AT_BOOT;
+
+	/* Check if pstate has actually changed */
+	if (flags == flash_read_pstate())
+		return EC_SUCCESS;
+
+	/* Cache the old copy for read/modify/write. */
+	memcpy(&newpstate, pstate, sizeof(newpstate));
+	validate_pstate_struct(&newpstate);
+
 	if (flags & EC_FLASH_PROTECT_RO_AT_BOOT)
-		pstate.flags |= PERSIST_FLAG_PROTECT_RO;
-	return flash_physical_write(CONFIG_FW_PSTATE_OFF, sizeof(pstate),
-				    (const char *)&pstate);
+		newpstate.flags |= PERSIST_FLAG_PROTECT_RO;
+	else
+		newpstate.flags &= ~PERSIST_FLAG_PROTECT_RO;
+	newpstate.valid_fields |= PSTATE_VALID_FLAGS;
+
+	return flash_write_pstate_data(&newpstate);
 }
 
+/**
+ * Write persistent serial number to pstate, erasing if necessary.
+ *
+ * @param serialno		New iascii serial number to set in pstate.
+ * @return EC_SUCCESS, or nonzero if error.
+ */
+static int flash_write_pstate_serial(const char *serialno)
+{
+	int i;
+	struct persist_state newpstate;
+	const struct persist_state *pstate =
+		(const struct persist_state *)
+		flash_physical_dataptr(CONFIG_FW_PSTATE_OFF);
+
+	/* Check that this is OK */
+	if (!serialno)
+		return EC_ERROR_INVAL;
+
+	/* Cache the old copy for read/modify/write. */
+	memcpy(&newpstate, pstate, sizeof(newpstate));
+	validate_pstate_struct(&newpstate);
+
+	/* Copy in serialno. */
+	for (i = 0; i < SERIALNO_MAX - 1; i++) {
+		newpstate.serialno[i] = serialno[i];
+		if (serialno[i] == 0)
+			break;
+	}
+	for (; i < SERIALNO_MAX; i++)
+		newpstate.serialno[i] = 0;
+	newpstate.valid_fields |= PSTATE_VALID_SERIALNO;
+
+	return flash_write_pstate_data(&newpstate);
+}
+
+
+
+
 #else /* !CONFIG_FLASH_PSTATE_BANK */
 
 /**
@@ -349,6 +453,24 @@ int flash_erase(int offset, int size)
 	return flash_physical_erase(offset, size);
 }
 
+const char *flash_read_serial(void)
+{
+#if defined(CONFIG_FLASH_PSTATE) && defined(CONFIG_FLASH_PSTATE_BANK)
+	return flash_read_pstate_serial();
+#else
+	return 0;
+#endif
+}
+
+int flash_write_serial(const char *serialno)
+{
+#if defined(CONFIG_FLASH_PSTATE) && defined(CONFIG_FLASH_PSTATE_BANK)
+	return flash_write_pstate_serial(serialno);
+#else
+	return EC_ERROR_UNIMPLEMENTED;
+#endif
+}
+
 int flash_protect_at_boot(enum flash_wp_range range)
 {
 #ifdef CONFIG_FLASH_PSTATE
diff --git a/include/config.h b/include/config.h
index 591af79c5f..3ecf920140 100644
--- a/include/config.h
+++ b/include/config.h
@@ -2011,6 +2011,9 @@
  */
 #undef CONFIG_USB_PORT_POWER_SMART_INVERTED
 
+/* Support programmable USB device iSerial field. */
+#undef CONFIG_USB_SERIALNO
+
 /******************************************************************************/
 /* USB port switch */
 
diff --git a/include/flash.h b/include/flash.h
index b065e7bb1b..03a6e89c25 100644
--- a/include/flash.h
+++ b/include/flash.h
@@ -245,4 +245,20 @@ uint32_t flash_get_protect(void);
  */
 int flash_set_protect(uint32_t mask, uint32_t flags);
 
+/**
+ * Get the serial number from flash.
+ *
+ * @return char * ascii serial number string.
+ */
+const char *flash_read_serial(void);
+
+/**
+ * Set the serial number in flash.
+ *
+ * @param serialno	ascii serial number string < 30 char.
+ *
+ * @return success status.
+ */
+int flash_write_serial(const char *serialno);
+
 #endif  /* __CROS_EC_FLASH_H */
diff --git a/include/usb_descriptor.h b/include/usb_descriptor.h
index baa6e6421b..a29b9eda76 100644
--- a/include/usb_descriptor.h
+++ b/include/usb_descriptor.h
@@ -233,6 +233,24 @@ struct usb_setup_packet {
 		WIDESTR(str) \
 	}
 
+#ifdef CONFIG_USB_SERIALNO
+/* String Descriptor for USB, for editable strings. */
+#define USB_STRING_LEN 30
+struct usb_string_desc {
+	uint8_t _len;
+	uint8_t _type;
+	wchar_t _data[USB_STRING_LEN];
+};
+#define USB_WR_STRING_DESC(str) \
+	(&(struct usb_string_desc) { \
+		/* As above, two bytes metadata, no null terminator. */ \
+		sizeof(WIDESTR(str)) + 2 - 2, \
+		USB_DT_STRING, \
+		WIDESTR(str) \
+})
+extern struct usb_string_desc *usb_serialno_desc;
+#endif
+
 /* Use these macros for declaring descriptors, to order them properly */
 #define USB_CONF_DESC(name) CONCAT2(usb_desc_, name)			\
 	__attribute__((section(".rodata.usb_desc_" STRINGIFY(name))))