servo_micro: add initial servo_micro build

* Update flash_ec to allow flashing servo_micro
* Add servo_micro build

BUG=chromium:571477
BRANCH=None
TEST=updated servod is able to control gpio, gpio extender,
     SPI flash, ec uart, ap uart on test yoshi

Signed-off-by: Nick Sanders <nsanders@google.com>

Change-Id: I4d69c83ae581cb41da928a27c39b7152475d7ca8
Reviewed-on: https://chromium-review.googlesource.com/327214
Commit-Ready: Nick Sanders <nsanders@chromium.org>
Tested-by: Nick Sanders <nsanders@chromium.org>
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>

8 files changed, 602 insertions, 1 deletions

diff --git a/board/servo_micro/Makefile b/board/servo_micro/Makefile
new file mode 120000
index 0000000000..94aaae2c4d
--- /dev/null
+++ b/board/servo_micro/Makefile
@@ -0,0 +1 @@
+../../Makefile
\ No newline at end of file
diff --git a/board/servo_micro/board.c b/board/servo_micro/board.c
new file mode 100644
index 0000000000..f22bda4342
--- /dev/null
+++ b/board/servo_micro/board.c
@@ -0,0 +1,261 @@
+/* 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.
+ */
+/* Servo micro board configuration */
+
+#include "common.h"
+#include "ec_version.h"
+#include "gpio.h"
+#include "hooks.h"
+#include "i2c.h"
+#include "queue_policies.h"
+#include "registers.h"
+#include "spi.h"
+#include "task.h"
+#include "usart-stm32f0.h"
+#include "usart_tx_dma.h"
+#include "usart_rx_dma.h"
+#include "usb_gpio.h"
+#include "usb_i2c.h"
+#include "usb_spi.h"
+#include "usb-stream.h"
+#include "util.h"
+
+
+/******************************************************************************
+ * Build GPIO tables and expose a subset of the GPIOs over USB.
+ */
+
+#include "gpio_list.h"
+
+static enum gpio_signal const usb_gpio_list[] = {
+GPIO_UART1_EN_L,
+GPIO_SERVO_JTAG_TRST_L,
+GPIO_SPI1_BUF_EN_L,
+GPIO_SPI2_BUF_EN_L,
+GPIO_UART2_EN_L,
+GPIO_SPI1_VREF_33,
+GPIO_SPI1_VREF_18,
+GPIO_SPI2_VREF_33,
+GPIO_SPI2_VREF_18,
+GPIO_SERVO_JTAG_TRST_DIR,
+GPIO_SERVO_JTAG_TDI_DIR,
+GPIO_TCA6416_RESET_L
+};
+
+/*
+ * This instantiates struct usb_gpio_config const usb_gpio, plus several other
+ * variables, all named something beginning with usb_gpio_
+ */
+USB_GPIO_CONFIG(usb_gpio,
+		usb_gpio_list,
+		USB_IFACE_GPIO,
+		USB_EP_GPIO);
+
+
+/******************************************************************************
+ * Forward UARTs as a USB serial interface.
+ */
+
+#define USB_STREAM_RX_SIZE	16
+#define USB_STREAM_TX_SIZE	16
+
+/******************************************************************************
+ * Forward USART2 as a simple USB serial interface.
+ */
+
+static struct usart_config const usart2;
+struct usb_stream_config const usart2_usb;
+
+static struct queue const usart2_to_usb = QUEUE_DIRECT(64, uint8_t,
+	usart2.producer, usart2_usb.consumer);
+static struct queue const usb_to_usart2 = QUEUE_DIRECT(64, uint8_t,
+	usart2_usb.producer, usart2.consumer);
+
+static struct usart_config const usart2 =
+	USART_CONFIG(usart2_hw,
+		usart_rx_interrupt,
+		usart_tx_interrupt,
+		115200,
+		usart2_to_usb,
+		usb_to_usart2);
+
+USB_STREAM_CONFIG(usart2_usb,
+	USB_IFACE_USART2_STREAM,
+	USB_STR_USART2_STREAM_NAME,
+	USB_EP_USART2_STREAM,
+	USB_STREAM_RX_SIZE,
+	USB_STREAM_TX_SIZE,
+	usb_to_usart2,
+	usart2_to_usb)
+
+
+/******************************************************************************
+ * Forward USART3 as a simple USB serial interface.
+ */
+
+static struct usart_config const usart3;
+struct usb_stream_config const usart3_usb;
+
+static struct queue const usart3_to_usb = QUEUE_DIRECT(64, uint8_t,
+	usart3.producer, usart3_usb.consumer);
+static struct queue const usb_to_usart3 = QUEUE_DIRECT(64, uint8_t,
+	usart3_usb.producer, usart3.consumer);
+
+static struct usart_config const usart3 =
+	USART_CONFIG(usart3_hw,
+		usart_rx_interrupt,
+		usart_tx_interrupt,
+		115200,
+		usart3_to_usb,
+		usb_to_usart3);
+
+USB_STREAM_CONFIG(usart3_usb,
+	USB_IFACE_USART3_STREAM,
+	USB_STR_USART3_STREAM_NAME,
+	USB_EP_USART3_STREAM,
+	USB_STREAM_RX_SIZE,
+	USB_STREAM_TX_SIZE,
+	usb_to_usart3,
+	usart3_to_usb)
+
+
+/******************************************************************************
+ * Forward USART4 as a simple USB serial interface.
+ */
+
+static struct usart_config const usart4;
+struct usb_stream_config const usart4_usb;
+
+static struct queue const usart4_to_usb = QUEUE_DIRECT(64, uint8_t,
+	usart4.producer, usart4_usb.consumer);
+static struct queue const usb_to_usart4 = QUEUE_DIRECT(64, uint8_t,
+	usart4_usb.producer, usart4.consumer);
+
+static struct usart_config const usart4 =
+	USART_CONFIG(usart4_hw,
+		usart_rx_interrupt,
+		usart_tx_interrupt,
+		115200,
+		usart4_to_usb,
+		usb_to_usart4);
+
+USB_STREAM_CONFIG(usart4_usb,
+	USB_IFACE_USART4_STREAM,
+	USB_STR_USART4_STREAM_NAME,
+	USB_EP_USART4_STREAM,
+	USB_STREAM_RX_SIZE,
+	USB_STREAM_TX_SIZE,
+	usb_to_usart4,
+	usart4_to_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_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"),
+	[USB_STR_USART3_STREAM_NAME]  = USB_STRING_DESC("Servo UART2"),
+	[USB_STR_USART2_STREAM_NAME]  = USB_STRING_DESC("Servo UART1"),
+};
+
+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.
+ */
+
+/* SPI devices */
+/* Set clock divider to 7 since our SPI routing is non-optimal. */
+const struct spi_device_t spi_devices[] = {
+	{ CONFIG_SPI_FLASH_PORT, 7, GPIO_SPI_CS},
+};
+const unsigned int spi_devices_used = ARRAY_SIZE(spi_devices);
+
+void usb_spi_board_enable(struct usb_spi_config const *config)
+{
+	/* Remap SPI2 to DMA channels 6 and 7 */
+	/* STM32F072 SPI2 defaults to using DMA channels 4 and 5 */
+	/* but cros_ec hardcodes a 6/7 assumption in registers.h */
+	STM32_SYSCFG_CFGR1 |= (1 << 24);
+
+	/* Configure SPI GPIOs */
+	gpio_config_module(MODULE_SPI_FLASH, 1);
+
+	/* Set all four SPI pins to high speed */
+	STM32_GPIO_OSPEEDR(GPIO_B) |= 0xff000000;
+
+	/* Enable clocks to SPI2 module */
+	STM32_RCC_APB1ENR |= STM32_RCC_PB1_SPI2;
+
+	/* Reset SPI2 */
+	STM32_RCC_APB1RSTR |= STM32_RCC_PB1_SPI2;
+	STM32_RCC_APB1RSTR &= ~STM32_RCC_PB1_SPI2;
+
+	spi_enable(CONFIG_SPI_FLASH_PORT, 1);
+}
+
+void usb_spi_board_disable(struct usb_spi_config const *config)
+{
+	spi_enable(CONFIG_SPI_FLASH_PORT, 0);
+
+	/* Disable clocks to SPI2 module */
+	STM32_RCC_APB1ENR &= ~STM32_RCC_PB1_SPI2;
+
+	/* Release SPI GPIOs */
+	gpio_config_module(MODULE_SPI_FLASH, 0);
+}
+
+USB_SPI_CONFIG(usb_spi, USB_IFACE_SPI, USB_EP_SPI);
+
+
+/******************************************************************************
+ * Support I2C bridging over USB, this requires usb_i2c_board_enable and
+ * usb_i2c_board_disable to be defined to enable and disable the SPI bridge.
+ */
+
+/* I2C ports */
+const struct i2c_port_t i2c_ports[] = {
+	{"master", I2C_PORT_MASTER, 100,
+		GPIO_MASTER_I2C_SCL, GPIO_MASTER_I2C_SDA},
+};
+const unsigned int i2c_ports_used = ARRAY_SIZE(i2c_ports);
+
+USB_I2C_CONFIG(usb_i2c, USB_IFACE_I2C, USB_EP_I2C);
+
+
+/******************************************************************************
+ * Initialize board.
+ */
+static void board_init(void)
+{
+	/* USB to serial queues */
+	queue_init(&usart2_to_usb);
+	queue_init(&usb_to_usart2);
+	queue_init(&usart3_to_usb);
+	queue_init(&usb_to_usart3);
+	queue_init(&usart4_to_usb);
+	queue_init(&usb_to_usart4);
+
+	/* UART init */
+	usart_init(&usart2);
+	usart_init(&usart3);
+	usart_init(&usart4);
+
+	/* Enable GPIO expander. */
+	gpio_set_level(GPIO_TCA6416_RESET_L, 1);
+
+	/* Structured enpoints */
+	usb_spi_enable(&usb_spi, 1);
+}
+DECLARE_HOOK(HOOK_INIT, board_init, HOOK_PRIO_DEFAULT);
diff --git a/board/servo_micro/board.h b/board/servo_micro/board.h
new file mode 100644
index 0000000000..810fecb60a
--- /dev/null
+++ b/board/servo_micro/board.h
@@ -0,0 +1,103 @@
+/* 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.
+ */
+
+/* Servo micro configuration */
+
+#ifndef __CROS_EC_BOARD_H
+#define __CROS_EC_BOARD_H
+
+/* 48 MHz SYSCLK clock frequency */
+#define CPU_CLOCK 48000000
+
+/* Enable USART1,3,4 and USB streams */
+#define CONFIG_STREAM_USART
+#define CONFIG_STREAM_USART2
+#define CONFIG_STREAM_USART3
+#define CONFIG_STREAM_USART4
+#define CONFIG_STREAM_USB
+#define CONFIG_CMD_USART_INFO
+
+/* The UART console is on USART1 (PA9/PA10) */
+#undef CONFIG_UART_CONSOLE
+#define CONFIG_UART_CONSOLE 1
+
+/* Optional features */
+#define CONFIG_STM_HWTIMER32
+#define CONFIG_HW_CRC
+
+/* USB Configuration */
+#define CONFIG_USB
+#define CONFIG_USB_PID 0x501a
+#define CONFIG_USB_CONSOLE
+
+/* USB interface indexes (use define rather than enum to expand them) */
+#define USB_IFACE_USART4_STREAM  0
+#define USB_IFACE_GPIO    1
+#define USB_IFACE_SPI     2
+#define USB_IFACE_CONSOLE 3
+#define USB_IFACE_I2C     4
+#define USB_IFACE_USART3_STREAM  5
+#define USB_IFACE_USART2_STREAM  6
+#define USB_IFACE_COUNT   7
+
+/* USB endpoint indexes (use define rather than enum to expand them) */
+#define USB_EP_CONTROL 0
+#define USB_EP_USART4_STREAM  1
+#define USB_EP_GPIO    2
+#define USB_EP_SPI     3
+#define USB_EP_CONSOLE 4
+#define USB_EP_I2C     5
+#define USB_EP_USART3_STREAM  6
+#define USB_EP_USART2_STREAM  7
+#define USB_EP_COUNT   8
+
+/* Enable control of GPIOs over USB */
+#define CONFIG_USB_GPIO
+
+/* Enable control of SPI over USB */
+#define CONFIG_USB_SPI
+#define CONFIG_SPI_MASTER
+#define CONFIG_SPI_FLASH_PORT    0  /* First SPI master port */
+
+/* This is not actually an EC so disable some features. */
+#undef CONFIG_WATCHDOG_HELP
+#undef CONFIG_LID_SWITCH
+
+/* Enable control of I2C over USB */
+#define CONFIG_USB_I2C
+#define CONFIG_I2C
+#define CONFIG_I2C_MASTER
+#define I2C_PORT_MASTER 0
+
+/*
+ * Allow dangerous commands all the time, since we don't have a write protect
+ * switch.
+ */
+#define CONFIG_SYSTEM_UNLOCKED
+
+#ifndef __ASSEMBLER__
+
+/* Timer selection */
+#define TIM_CLOCK32 2
+
+#include "gpio_signal.h"
+
+/* USB string indexes */
+enum usb_strings {
+	USB_STR_DESC = 0,
+	USB_STR_VENDOR,
+	USB_STR_PRODUCT,
+	USB_STR_SERIALNO,
+	USB_STR_VERSION,
+	USB_STR_USART4_STREAM_NAME,
+	USB_STR_CONSOLE_NAME,
+	USB_STR_USART3_STREAM_NAME,
+	USB_STR_USART2_STREAM_NAME,
+
+	USB_STR_COUNT
+};
+
+#endif /* !__ASSEMBLER__ */
+#endif /* __CROS_EC_BOARD_H */
diff --git a/board/servo_micro/build.mk b/board/servo_micro/build.mk
new file mode 100644
index 0000000000..0e069a31ad
--- /dev/null
+++ b/board/servo_micro/build.mk
@@ -0,0 +1,13 @@
+# -*- makefile -*-
+# 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.
+#
+# Board specific files build
+
+# the IC is STmicro STM32F072RBT6
+CHIP:=stm32
+CHIP_FAMILY:=stm32f0
+CHIP_VARIANT:=stm32f07x
+
+board-y=board.o
diff --git a/board/servo_micro/ec.tasklist b/board/servo_micro/ec.tasklist
new file mode 100644
index 0000000000..1944ef3874
--- /dev/null
+++ b/board/servo_micro/ec.tasklist
@@ -0,0 +1,21 @@
+/* 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.
+ */
+
+/**
+ * List of enabled tasks in the priority order
+ *
+ * The first one has the lowest priority.
+ *
+ * For each task, use the macro TASK_ALWAYS(n, r, d, s) for base tasks and
+ * TASK_NOTEST(n, r, d, s) for tasks that can be excluded in test binaries,
+ * where :
+ * 'n' in the name of the task
+ * 'r' in the main routine of the task
+ * 'd' in an opaque parameter passed to the routine at startup
+ * 's' is the stack size in bytes; must be a multiple of 8
+ */
+#define CONFIG_TASK_LIST \
+	TASK_ALWAYS(HOOKS,   hook_task,    NULL, TASK_STACK_SIZE) \
+	TASK_ALWAYS(CONSOLE, console_task, NULL, TASK_STACK_SIZE)
diff --git a/board/servo_micro/gpio.inc b/board/servo_micro/gpio.inc
new file mode 100644
index 0000000000..cca65d857d
--- /dev/null
+++ b/board/servo_micro/gpio.inc
@@ -0,0 +1,60 @@
+/* -*- mode:c -*-
+ *
+ * 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.
+ */
+
+/* Outputs */
+GPIO(UART1_EN_L, PIN(A, 8), GPIO_OUT_HIGH)
+GPIO(SERVO_JTAG_TRST_L, PIN(A, 13), GPIO_OUT_LOW)
+GPIO(SPI1_BUF_EN_L, PIN(A, 14), GPIO_OUT_HIGH)
+GPIO(SPI2_BUF_EN_L, PIN(A, 15), GPIO_OUT_HIGH)
+
+GPIO(UART2_EN_L, PIN(B, 0), GPIO_OUT_HIGH)
+GPIO(SPI1_VREF_33, PIN(B, 2), GPIO_OUT_LOW)
+GPIO(SPI1_VREF_18, PIN(B, 3), GPIO_OUT_LOW)
+GPIO(SPI2_VREF_33, PIN(B, 4), GPIO_OUT_LOW)
+GPIO(SPI2_VREF_18, PIN(B, 5), GPIO_OUT_LOW)
+GPIO(SERVO_JTAG_TRST_DIR, PIN(B, 6), GPIO_OUT_HIGH)
+GPIO(SERVO_JTAG_TDI_DIR, PIN(B, 7), GPIO_OUT_HIGH)
+
+GPIO(TCA6416_RESET_L, PIN(C, 13), GPIO_OUT_LOW)
+GPIO(SERVO_JTAG_TMS_DIR, PIN(C, 14), GPIO_OUT_LOW)
+GPIO(SERVO_JTAG_TDO_SEL, PIN(C, 15), GPIO_OUT_LOW)
+
+/* Inputs */
+GPIO(SERVO_JTAG_TMS, PIN(A, 4), GPIO_INPUT)
+GPIO(SERVO_JTAG_TCK, PIN(A, 5), GPIO_INPUT)
+GPIO(SERVO_JTAG_MUX_TDO, PIN(A, 6), GPIO_INPUT)
+GPIO(SERVO_JTAG_TDI, PIN(A, 7), GPIO_INPUT)
+
+GPIO(SERVO_JTAG_RTCK, PIN(B, 1), GPIO_INPUT)
+
+/* Flash SPI interface */
+GPIO(SPI_CS,   PIN(B, 12), GPIO_OUT_HIGH)
+GPIO(SPI_CLK,  PIN(B, 13), GPIO_INPUT)
+GPIO(SPI_MISO, PIN(B, 14), GPIO_INPUT)
+GPIO(SPI_MOSI, PIN(B, 15), GPIO_INPUT)
+
+/* I2C pins should be configured as inputs until I2C module is    */
+/* initialized. This will avoid driving the lines unintentionally.*/
+GPIO(MASTER_I2C_SCL,       PIN(B, 8), GPIO_INPUT)
+GPIO(MASTER_I2C_SDA,       PIN(B, 9), GPIO_INPUT)
+
+/* Unimplemented signals since we are not an EC */
+UNIMPLEMENTED(ENTERING_RW)
+UNIMPLEMENTED(WP_L)
+
+ALTERNATE(PIN_MASK(A, 0x0600), 1, MODULE_UART, 0) /* USART1: PA09/PA10 - Servo stm32 console UART*/
+ALTERNATE(PIN_MASK(A, 0x000C), 1, MODULE_USART, 0) /* USART2: PA2/PA3 - Servo UART1 */
+ALTERNATE(PIN_MASK(B, 0x0C00), 4, MODULE_USART, 0) /* USART3: PB10/PB11 - Servo UART2 */
+/* Servo UART3 (USART4) is broken on servo micro rev. 1 */
+// ALTERNATE(PIN_MASK(A, 0x0003), 4, MODULE_USART, 0) /* USART4: PA0/PA1 - Servo UART3 */
+/* Expose Servo UART3 as GPIOs for debugging. */
+GPIO(UART3_TX, PIN(A, 0), GPIO_INPUT)
+GPIO(UART3_RX, PIN(A, 1), GPIO_INPUT)
+
+ALTERNATE(PIN_MASK(B, 0x0300), 1, MODULE_I2C, 0) /* I2C MASTER:PB8/9 GPIO_ODR_HIGH */
+
+ALTERNATE(PIN_MASK(B, 0xE000), 0, MODULE_SPI_FLASH, 0) /* SPI: PB15 - PB12 MOSI, MISO, CLK, CS */
diff --git a/extra/usb_spi/stm32spi.py b/extra/usb_spi/stm32spi.py
new file mode 100755
index 0000000000..ecd4edb8e9
--- /dev/null
+++ b/extra/usb_spi/stm32spi.py
@@ -0,0 +1,140 @@
+#!/usr/bin/python2
+# 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.
+
+
+# Test program to access SPI via stm32 raiden debug spi.
+
+import usb
+import usb.core
+import usb.util
+
+class SSpiBus(object):
+  """SPI bus class to access devices on the bus.
+
+  Usage:
+    bus = SSpiBus()
+    # read 1 byte from register(0x16)
+    bus.wr_rd([0x16], 1)
+    # write 2 bytes to register(0x20)
+    bus.wr_rd([0x20, 0x01, 0x02])
+
+  Instance Variables:
+    _dev: pyUSB device object
+    _read_ep: pyUSB read endpoint for this interface
+    _write_ep: pyUSB write endpoint for this interface
+  """
+  def __init__(self, vendor=0x18d1,
+               product=0x501a, interface=2, serialname=None):
+    # Find the stm32.
+    dev = usb.core.find(idVendor=vendor, idProduct=product)
+    if dev is None:
+      raise Exception("SPI", "USB device not found")
+
+    print "Found stm32: %04x:%04x" % (vendor, product)
+    self._dev = dev
+
+    # Get an endpoint instance.
+    cfg = dev.get_active_configuration()
+    intf = usb.util.find_descriptor(cfg, bInterfaceNumber=interface)
+    self._intf = intf
+    print "InterfaceNumber: %s" % intf.bInterfaceNumber
+
+    read_ep = usb.util.find_descriptor(
+        intf,
+        # match the first IN endpoint
+        custom_match=\
+        lambda e: \
+            usb.util.endpoint_direction(e.bEndpointAddress) == \
+            usb.util.ENDPOINT_IN
+    )
+
+    self._read_ep = read_ep
+    print "Reader endpoint: 0x%x" % read_ep.bEndpointAddress
+
+    write_ep = usb.util.find_descriptor(
+        intf,
+        # match the first OUT endpoint
+        custom_match=\
+        lambda e: \
+            usb.util.endpoint_direction(e.bEndpointAddress) == \
+            usb.util.ENDPOINT_OUT
+    )
+
+    self._write_ep = write_ep
+    print "Writer endpoint: 0x%x" % write_ep.bEndpointAddress
+
+    self.enable(True)
+    print "Set up stm32 spi"
+
+  def enable(self, enable):
+    # USB_RIR_OUT = 0 | USB_TYPE_VENDOR = (0x02 << 5) |
+    #     USB_RECIP_INTERFACE = 0x01
+    bmRequestType = 0x41
+    # USB_SPI_REQ_ENABLE  = 0x0000, USB_SPI_REQ_DISABLE = 0x0001
+    if enable:
+      bmRequest = 0x0
+    else:
+      bmRequest = 0x1
+
+    print "ctrl_transfer(0x%x, 0x%x, 0, 0x%x, null)" % (
+        bmRequestType, bmRequest, self._intf.bInterfaceNumber)
+    ret = self._dev.ctrl_transfer(
+        bmRequestType, bmRequest, 0, self._intf.bInterfaceNumber, '')
+    print "ctrl_transfer ret - %s" % ret
+
+
+
+
+  def wr_rd(self, write_list, read_count=None):
+    """Implements hdctools wr_rd() interface.
+
+    This function writes byte values list to I2C device, then reads
+    byte values from the same device.
+
+    Args:
+      write_list: list of output byte values [0~255].
+      read_count: number of byte values to read from device.
+
+    Interface:
+      write: [write_count, read_count, data ... ]
+      read: [data .. ]
+    """
+    print "SSpi.wr_rd(write_list=%s, read_count=%s)" % (
+        write_list, read_count)
+
+    # Clean up args from python style to correct types.
+    write_length = 0
+    if write_list:
+      write_length = len(write_list)
+    if not read_count:
+      read_count = 0
+
+    # Send wr_rd command to stm32.
+    cmd = [write_length, read_count] + write_list
+    print "WR: %s" % cmd
+    ret = self._write_ep.write(cmd, 100)
+
+    print "RET: %s " % ret
+
+    # Read back response if necessary.
+    bytesread = self._read_ep.read(read_count + 2, 1000)
+    print "BYTES: %s " % bytesread
+
+    if len(bytesread) < 2:
+      raise Exception("SPI", "Read status failed.")
+
+    print "STATUS: 0x%02x%02x" % (int(bytesread[1]), int(bytesread[0]))
+    return bytesread[2:]
+
+
+def main():
+  bus = SSpiBus()
+  # write 2 bytes to register(0x20)
+  bus.wr_rd([0x90, 0x00, 0x00, 0x00], 2)
+  # read 1 byte from register(0x16)
+  bus.wr_rd([0x9f], 3)
+
+if __name__ == "__main__":
+  main()
diff --git a/util/flash_ec b/util/flash_ec
index 9aa737ddab..90e4e435fd 100755
--- a/util/flash_ec
+++ b/util/flash_ec
@@ -54,7 +54,6 @@ BOARDS_STM32=(
 	big
 	blaze
 	chell_pd
-	discovery
 	glados_pd
 	honeybuns
 	jerry
@@ -82,6 +81,9 @@ BOARDS_STM32_DFU=(
 	dingdong
 	hoho
 	twinkie
+	discovery
+	servo_v4
+	servo_micro
 )
 
 BOARDS_NPCX_5M5G_JTAG=(