common: remove CONFIG_SMBUS dead code

CONFIG_SMBUS is not used.  Cleaning up the code by
removing this.

Added a comment to document the removal and why.  This will
give a way to find the code if we ever needed to bring it back

BUG=chromium:982316
BRANCH=none
TEST=make buildall

Change-Id: I40703a95bc849538e1aee32f6f96beab811285bd
Signed-off-by: Denis Brockus <dbrockus@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1704279
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>

2 files changed, 16 insertions, 159 deletions

diff --git a/include/config.h b/include/config.h
index 546833b26f..3eb6d671d6 100644
--- a/include/config.h
+++ b/include/config.h
@@ -3054,7 +3054,22 @@
 #undef CONFIG_SOFTWARE_CTZ
 
 /* Support smbus interface */
-#undef CONFIG_SMBUS
+/*
+ * Deprecated in
+ * https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1704279
+ *
+ * It hasn't been used in over 2 years
+ * https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/452459/
+ * and was only used by one board (pyro).
+ *
+ * I2C and SMBus are compatible at the physical layer. The data transfer
+ * paradigm is different. Some of our batteries are using SMbus style
+ * transfers now, they are just using i2cxfer directly to accomplish it.
+ *
+ * I doubt the SMBus code will get revived, but we do have it in revision
+ * history if we ever need it.
+ */
+/* #undef CONFIG_SMBUS */
 
 /* Support SPI interfaces */
 #undef CONFIG_SPI
diff --git a/include/smbus.h b/include/smbus.h
deleted file mode 100644
index 41c0287dab..0000000000
--- a/include/smbus.h
+++ /dev/null
@@ -1,158 +0,0 @@
-/* Copyright 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 __CROS_EC_SMBUS_H
-#define __CROS_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 busy
- *       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 receiving 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 /* __CROS_EC_SMBUS_H */