i2c_passthru: fix virtual battery operation

In some cases, the virtual battery code creates
transactions that violate SB spec.

One example:
If the host command is structured as two messages -
a write to 0x03 (reg addr), followed by two bytes of write data,
the first byte of the second message (write data) will be sent to
virtual_battery_read(), as if it were a reg read request.

Let's do the following change for virtual battery:
1. Parse the command more carefully with state machines.
2. Support write caching for some critical registers.
3. Cache more attributes (0x03 and 0x0f).

BUG=chrome-os-partner:59239, chromium:659819
BRANCH=none
TEST='power_supply_info' works on kevin

Change-Id: Icdeb12b21f0dc3c329f29b206b7b9395ca4c9998
Reviewed-on: https://chromium-review.googlesource.com/407987
Commit-Ready: Philip Chen <philipchen@chromium.org>
Tested-by: Philip Chen <philipchen@chromium.org>
Reviewed-by: Shawn N <shawnn@chromium.org>

2 files changed, 49 insertions, 11 deletions

diff --git a/include/charge_state_v2.h b/include/charge_state_v2.h
index e5855c2fe1..70ca47f6d3 100644
--- a/include/charge_state_v2.h
+++ b/include/charge_state_v2.h
@@ -73,16 +73,5 @@ enum ec_status charger_profile_override_set_param(uint32_t param,
  */
 int charge_set_input_current_limit(int ma, int mv);
 
-
-/**
- * Get value of battery parameter from charge state.
- *
- * @param batt_param	battery parameter
- * @param dest		Destination buffer for data
- * @param read_len	Number of bytes to write to buffer
- * @return EC_SUCCESS if successful, non-zero if error.
- *
- */
-int virtual_battery_read(uint8_t batt_param, uint8_t *dest, int read_len);
 #endif /* __CROS_EC_CHARGE_STATE_V2_H */
 
diff --git a/include/virtual_battery.h b/include/virtual_battery.h
new file mode 100644
index 0000000000..c686a76172
--- /dev/null
+++ b/include/virtual_battery.h
@@ -0,0 +1,49 @@
+/* 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.
+ */
+
+#ifndef __CROS_EC_VIRTUAL_BATTERY_H
+#define __CROS_EC_VIRTUAL_BATTERY_H
+
+#if defined(CONFIG_I2C_VIRTUAL_BATTERY) && defined(CONFIG_BATTERY_SMART)
+#define VIRTUAL_BATTERY_ADDR BATTERY_ADDR
+#endif
+
+/**
+ * Read/write value of battery parameter from charge state.
+ *
+ * @param batt_cmd_head	The beginning of the smart battery command
+ * @param dest		Destination buffer for data
+ * @param read_len	Number of bytes to read to the buffer
+ * @param write_len	Number of bytes to write
+ * @return EC_SUCCESS if successful, non-zero if error.
+ *
+ */
+int virtual_battery_operation(const uint8_t *batt_cmd_head,
+			      uint8_t *dest,
+			      int read_len,
+			      int write_len);
+
+/**
+ * Parse a command for virtual battery function.
+ *
+ * @param resp		Pointer to the data structure to store the i2c messages
+ * @param in_len	Accumulative number of bytes read
+ * @param err_code	Pointer to the return value of i2c_xfer() or
+ *			virtual_battery_operation()
+ * @param xferflags	Flags
+ * @param read_len	Number of bytes to read
+ * @param write_len	Number of bytes to write
+ * @param out		Data to send
+ * @return EC_SUCCESS if successful, non-zero if error.
+ */
+int virtual_battery_handler(struct ec_response_i2c_passthru *resp,
+				   int in_len, int *err_code, int xferflags,
+				   int read_len, int write_len,
+				   const uint8_t *out);
+
+/* Reset the state machine and static variables. */
+void reset_parse_state(void);
+
+#endif /* __CROS_EC_VIRTUAL_BATTERY_H */