EC: Add smbus interface read & write APIs

Ref: http://smbus.org/specs/smbus20.pdf

- Support software CRC8 generation and checking.
- Support read/write word (2-bytes)
- Support read/write blocks (up to 32 bytes)

BUG=chrome-os-partner:24741
BRANCH=ToT,glimmer
TEST=Verified with smart battery firmware update application on glimmer.
Passed LGC & Simplo Battery.

Change-Id: Ic2e7f759af80c06741ed49fee1826213429fbf8a
Signed-off-by: Sheng-Liang Song <ssl@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/209747
Reviewed-by: Randall Spangler <rspangler@chromium.org>

5 files changed, 193 insertions, 1 deletions

diff --git a/include/common.h b/include/common.h
index cddcde31fa..eb4ebd7c32 100644
--- a/include/common.h
+++ b/include/common.h
@@ -88,6 +88,8 @@ enum ec_error_list {
 	EC_ERROR_NOT_POWERED = 8,
 	/* Failed because component is not calibrated */
 	EC_ERROR_NOT_CALIBRATED = 9,
+	/* Failed because CRC error */
+	EC_ERROR_CRC = 10,
 	/* Invalid console command param (PARAMn means parameter n is bad) */
 	EC_ERROR_PARAM1 = 11,
 	EC_ERROR_PARAM2 = 12,
diff --git a/include/config.h b/include/config.h
index 609d0943b2..8e0f1dd10a 100644
--- a/include/config.h
+++ b/include/config.h
@@ -1,4 +1,4 @@
-/* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
+/* Copyright (c) 2014 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.
  */
@@ -376,6 +376,9 @@
  */
 #undef CONFIG_CONSOLE_RESTRICTED_INPUT
 
+/* Include CRC-8 utility function */
+#undef CONFIG_CRC8
+
 /*****************************************************************************/
 /*
  * Debugging config
@@ -803,6 +806,9 @@
 /* Emulate the CLZ (Count Leading Zeros) in software for CPU lacking support */
 #undef CONFIG_SOFTWARE_CLZ
 
+/* Support smbus interface */
+#undef CONFIG_SMBUS
+
 /* Support SPI interfaces */
 #undef CONFIG_SPI
 
diff --git a/include/crc8.h b/include/crc8.h
new file mode 100644
index 0000000000..94980effc5
--- /dev/null
+++ b/include/crc8.h
@@ -0,0 +1,21 @@
+/* Copyright (c) 2014 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.
+ *
+ * Very simple 8-bit CRC function.
+ */
+#ifndef __EC_CRC8_H__
+#define __EC_CRC8_H__
+
+/**
+ * crc8
+ * Return CRC-8 of the data, using x^8 + x^2 + x + 1 polynomial.  A table-based
+ * algorithm would be faster, but for only a few bytes it isn't worth the code
+ * size.
+ * @param data uint8_t *, input, a pointer to input data
+ * @param len int, input, size of iput data in byte
+ * @return the crc-8 of the input data.
+ */
+uint8_t crc8(const uint8_t *data, int len);
+
+#endif /* __EC_CRC8_H__ */
diff --git a/include/i2c.h b/include/i2c.h
index 9cb884ba19..a4e105ddac 100644
--- a/include/i2c.h
+++ b/include/i2c.h
@@ -151,6 +151,11 @@ int i2c_read8(int port, int slave_addr, int offset, int *data);
 int i2c_write8(int port, int slave_addr, int offset, int data);
 
 /**
+ * @return non-zero if i2c bus is busy
+ */
+int i2c_is_busy(int port);
+
+/**
  * Attempt to unwedge an I2C bus.
  *
  * @param port I2C port
diff --git a/include/smbus.h b/include/smbus.h
new file mode 100644
index 0000000000..8f1bfeb9c9
--- /dev/null
+++ b/include/smbus.h
@@ -0,0 +1,158 @@
+/* Copyright (c) 2014 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.
+ *
+ * @file smbus.h
+ * @brief smbus interface APIs
+ * @see http://smbus.org/specs/smbus20.pdf
+ */
+#ifndef __EC_SMBUS_H__
+#define __EC_SMBUS_H__
+
+/** Maximum transfer of a SMBUS block transfer */
+#define SMBUS_MAX_BLOCK_SIZE 32
+
+/**
+ * smbus write word
+ *   write 2 byte data + 1 byte pec
+ */
+struct smbus_wr_word {
+	uint8_t slave_addr;/**< i2c_addr << 1 */
+	uint8_t smbus_cmd; /**< smbus cmd */
+	uint8_t data[3];   /**< smbus data */
+} __packed;
+
+/**
+ * smbus write block data
+ * smbus write 1 byte size + 32 byte data + 1 byte pec
+ */
+struct smbus_wr_block {
+	uint8_t slave_addr;/**< i2c_addr << 1 */
+	uint8_t smbus_cmd; /**< smbus cmd */
+	uint8_t size;      /**< write size */
+	uint8_t data[SMBUS_MAX_BLOCK_SIZE+1];
+} __packed;
+
+/**
+ * smbus read word
+ * smbus read 2 byte + 1 pec
+ */
+struct smbus_rd_word {
+	uint8_t slave_addr;   /**< i2c_addr << 1 */
+	uint8_t smbus_cmd;    /**< smbus cmd */
+	uint8_t slave_addr_rd;/**< (i2c_addr << 1) | 0x1 */
+	uint8_t data[3];      /**< smbus data */
+} __packed;
+
+/**
+ * smbus read block data
+ * smbus read 1 byte size + 32 byte data + 1 byte pec
+ */
+struct smbus_rd_block {
+	uint8_t slave_addr;   /**< i2c_addr << 1 */
+	uint8_t smbus_cmd;    /**< smbus cmd */
+	uint8_t slave_addr_rd;/**< (i2c_addr << 1) | 0x1 */
+	uint8_t size;         /**< read block size */
+	uint8_t data[SMBUS_MAX_BLOCK_SIZE+1]; /**< smbus data */
+} __packed;
+
+/**
+ * smbus_write_word
+ * smbus write 2 bytes
+ * @param i2c_port uint8_t, i2c port address
+ * @param slave_addr uint8_t, i2c slave address:= (i2c_addr << 1)
+ * @param smbus_cmd uint8_t, smbus command
+ * @param d16 uint16_t, 2-bytes data
+ * @return error_code
+ *       EC_SUCCESS if success; none-zero if fail
+ *       EC_ERROR_BUSY if interface is bussy
+ *       none zero error code if fail
+ */
+int smbus_write_word(uint8_t i2c_port, uint8_t slave_addr,
+			uint8_t smbus_cmd, uint16_t d16);
+
+/**
+ * smbus_write_block
+ * smbus write upto 32 bytes
+ *   case 1:  n-1 byte data, 1 byte PEC
+ *     [S][i2c Address][Wr=0][A][cmd][A] ...[Di][Ai]... [PEC][A][P]
+ *
+ *   case 2:  1 byte data-size, n -2 byte data, 1 byte PEC
+ *     [S][i2c Address][Wr=0][A][cmd][A][size][A] ...[Di][Ai]... [PEC][A][P]
+ *
+ * @param i2c_port uint8_t, i2c port address
+ * @param slave_addr uint8_t, i2c slave address:= (i2c_addr << 1)
+ * @param smbus_cmd uint8_t, smbus command
+ * @param data uint8_t *, n-bytes data
+ * @param len uint8_t,  data length
+ * @return error_code
+ *       EC_SUCCESS if success; none-zero if fail
+ *       EC_ERROR_BUSY if interface is bussy
+ *       none zero error code if fail
+ */
+int smbus_write_block(uint8_t i2c_port, uint8_t slave_addr,
+			uint8_t smbus_cmd, uint8_t *data, uint8_t len);
+
+/**
+ * smbus_read_word
+ * smbus read 2 bytes
+ * @param i2c_port uint8_t, i2c port address
+ * @param slave_addr uint8_t, i2c slave address:= (i2c_addr << 1)
+ * @param smbus_cmd uint8_t, smbus command
+ * @param p16 uint16_t *, a pointer to 2-bytes data
+ * @return error_code
+ *       EC_SUCCESS if success; none-zero if fail
+ *       EC_ERROR_BUSY if interface is bussy
+ *       none zero error code if fail
+ */
+int smbus_read_word(uint8_t i2c_port, uint8_t slave_addr,
+			uint8_t smbus_cmd, uint16_t *p16);
+
+/**
+ * smbus_read_block
+ * smbus read upto 32 bytes
+ * case 1:  n-1 byte data, 1 byte PEC
+ *    [S][i2c addr][Wr=0][A][cmd][A]
+ *    [S][i2c addr][Rd=1][A]...[Di][Ai]...[PEC][A][P]
+ *
+ * case 2:  1 byte data-size, n - 2 byte data, 1 byte PEC
+ *    [S][i2c addr][Wr=0][A][cmd][A]
+ *    [S][i2c addr][Rd=1][A][size][A]...[Di][Ai]...[PEC][A][P]
+ *
+ * @param i2c_port uint8_t, i2c port address
+ * @param slave_addr uint8_t, i2c slave address:= (i2c_addr << 1)
+ * @param smbus_cmd uint8_t, smbus command
+ * @param data uint8_t *, n-bytes data
+ * @param plen uint8_t *, a pointer data length
+ * @return error_code
+ *       EC_SUCCESS if success; none-zero if fail
+ *       EC_ERROR_BUSY if interface is bussy
+ *       none zero error code if fail
+ */
+int smbus_read_block(uint8_t i2c_port, uint8_t slave_addr,
+			uint8_t smbus_cmd, uint8_t *data, uint8_t *plen);
+
+/**
+ * smbus_read_string
+ * smbus read ascii string (upto 32-byte data + 1-byte NULL)
+ * Read bytestream from <slaveaddr>:<smbus_cmd> with format:
+ *     [length_N] [byte_0] [byte_1] ... [byte_N-1][byte_N='\0']
+ *
+ * <len>  : the max length of receving buffer. to read N bytes
+ *          ascii, len should be at least N+1 to include the
+ *          terminating 0 (NULL).
+ *
+ * @param i2c_port uint8_t, i2c port address
+ * @param slave_addr uint8_t, i2c slave address:= (i2c_addr << 1)
+ * @param smbus_cmd uint8_t, smbus command
+ * @param data uint8_t *, n-bytes data
+ * @param len uint8_t,  data length
+ * @return error_code
+ *       EC_SUCCESS if success; none-zero if fail
+ *       EC_ERROR_BUSY if interface is bussy
+ *       none zero error code if fail
+ */
+int smbus_read_string(int i2c_port, uint8_t slave_addr, uint8_t smbus_cmd,
+			uint8_t *data, uint8_t len);
+
+#endif /* __EC_SMBUS_H__ */