Support flash checksum command for re-transmit.

The LPC is not stable enough to test. Kodus Rong. He creates this idea
to checksum the partial content of flash for read/write/erase. This can
improve the robustness of flashrom.

BUG=none
TEST=Tested with flashrom.

Change-Id: I2a2f7b698a94674c03cbd8e3f15caf34f8986399

4 files changed, 64 insertions, 6 deletions

diff --git a/common/flash_commands.c b/common/flash_commands.c
index 95f1b9639e..e8e2c9591c 100644
--- a/common/flash_commands.c
+++ b/common/flash_commands.c
@@ -20,7 +20,7 @@
 
 static int command_flash_info(int argc, char **argv)
 {
-	uart_printf("Usable flash size: %d KB\n", flash_get_size());
+	uart_printf("Usable flash size: %d B\n", flash_get_size());
 	return EC_SUCCESS;
 }
 
@@ -212,6 +212,32 @@ enum lpc_status flash_command_get_info(uint8_t *data)
 }
 
 
+#ifdef SUPPORT_CHECKSUM
+enum lpc_status flash_command_checksum(uint8_t *data)
+{
+	struct lpc_params_flash_checksum *p =
+	                (struct lpc_params_flash_checksum *)data;
+	struct lpc_response_flash_checksum *r =
+	                (struct lpc_response_flash_checksum *)data;
+	uint8_t cs, byte;
+	int j;
+
+	for (cs = 0, j = 0; j < p->size; ++j) {
+		if (flash_read(p->offset + j, 1, &byte)) {
+			uart_printf("flash_read() error at 0x%02x.\n",
+			            p->offset + j);
+			return EC_LPC_STATUS_ERROR;
+		}
+		BYTE_IN(cs, byte);
+	}
+
+	r->checksum = cs;
+
+	return EC_LPC_STATUS_SUCCESS;
+}
+#endif
+
+
 enum lpc_status flash_command_read(uint8_t *data)
 {
 	struct lpc_params_flash_read *p =
@@ -322,4 +348,3 @@ int flash_commands_init(void)
 	console_register_commands(&command_group);
 	return EC_SUCCESS;
 }
-
diff --git a/common/host_command.c b/common/host_command.c
index 12790e4050..578fe33093 100644
--- a/common/host_command.c
+++ b/common/host_command.c
@@ -156,17 +156,22 @@ static void command_process(int slot)
 		lpc_send_host_response(slot, flash_command_erase(data));
 		return;
 	case EC_LPC_COMMAND_FLASH_WP_ENABLE:
-		lpc_send_host_response(flash_command_wp_enable(host_data));
+		lpc_send_host_response(slot, flash_command_wp_enable(data));
 		return;
 	case EC_LPC_COMMAND_FLASH_WP_GET_STATE:
-		lpc_send_host_response(flash_command_wp_get_state(host_data));
+		lpc_send_host_response(slot, flash_command_wp_get_state(data));
 		return;
 	case EC_LPC_COMMAND_FLASH_WP_SET_RANGE:
-		lpc_send_host_response(flash_command_wp_set_range(host_data));
+		lpc_send_host_response(slot, flash_command_wp_set_range(data));
 		return;
 	case EC_LPC_COMMAND_FLASH_WP_GET_RANGE:
-		lpc_send_host_response(flash_command_wp_get_range(host_data));
+		lpc_send_host_response(slot, flash_command_wp_get_range(data));
 		return;
+#ifdef SUPPORT_CHECKSUM
+	case EC_LPC_COMMAND_FLASH_CHECKSUM:
+		lpc_send_host_response(slot, flash_command_checksum(data));
+		return;
+#endif
 	default:
 		lpc_send_host_response(slot, EC_LPC_STATUS_INVALID_COMMAND);
 	}
diff --git a/include/flash_commands.h b/include/flash_commands.h
index 230dc4014d..5efc7e2a67 100644
--- a/include/flash_commands.h
+++ b/include/flash_commands.h
@@ -23,5 +23,9 @@ enum lpc_status flash_command_wp_enable(uint8_t *data);
 enum lpc_status flash_command_wp_get_state(uint8_t *data);
 enum lpc_status flash_command_wp_set_range(uint8_t *data);
 enum lpc_status flash_command_wp_get_range(uint8_t *data);
+#ifdef SUPPORT_CHECKSUM
+enum lpc_status flash_command_checksum(uint8_t *data);
+#endif
+
 
 #endif  /* __CROS_EC_FLASH_COMMANDS_H */
diff --git a/include/lpc_commands.h b/include/lpc_commands.h
index 37b54dd380..08b4d9c1d8 100644
--- a/include/lpc_commands.h
+++ b/include/lpc_commands.h
@@ -10,6 +10,14 @@
 
 #include <stdint.h>
 
+
+/* During the development stage, the LPC bus has high error bit rate.
+ * Using checksum can detect the error and trigger re-transmit.
+ * FIXME: remove this after mass production.
+ */
+#define SUPPORT_CHECKSUM
+
+
 /* I/O addresses for LPC commands */
 #define EC_LPC_ADDR_KERNEL_DATA   0x62
 #define EC_LPC_ADDR_KERNEL_CMD    0x66
@@ -180,5 +188,21 @@ struct lpc_response_flash_wp_gpio {
 	uint32_t value;
 } __attribute__ ((packed));
 
+#ifdef SUPPORT_CHECKSUM
+/* Checksum a range of flash datq */
+#define EC_LPC_COMMAND_FLASH_CHECKSUM 0x1f
+struct lpc_params_flash_checksum {
+	uint32_t offset;   /* Byte offset to read */
+	uint32_t size;     /* Size to read in bytes */
+} __attribute__ ((packed));
+struct lpc_response_flash_checksum {
+	uint8_t checksum;
+} __attribute__ ((packed));
+#define BYTE_IN(sum, byte) do {  \
+		sum = (sum << 1) | (sum >> 7);  \
+		sum ^= (byte ^ 0x53);  \
+	} while (0)
+#endif  /* SUPPORT_CHECKSUM */
+
 
 #endif  /* __CROS_EC_LPC_COMMANDS_H */