ec/google: Isolate EC bus protocol implementation.

The Chrome EC can be connected by different types of bus like LPC / I2C / SPI,
and the current implementation is only for LPC.

To support other types, we must first isolate the LPC protocol stuff and add
configuration variable (EC_GOOGLE_CHROMEEC_LPC) to specify bus type.

Verified by building google/link (with chromeec) configuration successfully.

Change-Id: Ib2920d8d935bcc77a5394e818f69e9265e26e8a0
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: http://review.coreboot.org/3068
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins)
Reviewed-by: David Hendricks <dhendrix@chromium.org>

1 files changed, 201 insertions, 0 deletions

diff --git a/src/ec/google/chromeec/ec_lpc.c b/src/ec/google/chromeec/ec_lpc.c
new file mode 100644
index 0000000000..6443592532
--- /dev/null
+++ b/src/ec/google/chromeec/ec_lpc.c
@@ -0,0 +1,201 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2013 Google Inc.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <stdint.h>
+#include <console/console.h>
+#include <arch/io.h>
+#include <delay.h>
+#include "ec.h"
+#include "ec_commands.h"
+
+static int google_chromeec_wait_ready(u16 port)
+{
+	u8 ec_status = inb(port);
+	u32 time_count = 0;
+
+	/*
+	 * One second is more than plenty for any EC operation to complete
+	 * (and the bus accessing/code execution) overhead will make the
+	 * timeout even longer.
+	 */
+#define MAX_EC_TIMEOUT_US 1000000
+
+	while (ec_status &
+	       (EC_LPC_CMDR_PENDING | EC_LPC_CMDR_BUSY)) {
+		udelay(1);
+		if (time_count++ == MAX_EC_TIMEOUT_US)
+			return -1;
+		ec_status = inb(port);
+	}
+	return 0;
+}
+
+static int google_chromeec_cmd_args_supported(void)
+{
+	if (inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID) == 'E' &&
+	    inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID + 1) == 'C' &&
+	    (inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_HOST_CMD_FLAGS) &
+	     EC_HOST_CMD_FLAG_LPC_ARGS_SUPPORTED))
+		return 1;
+
+	return 0;
+}
+
+static int google_chromeec_command_old(struct chromeec_command *cec_command)
+{
+	int i;
+
+	if (cec_command->cmd_version) {
+		printk(BIOS_ERR, "Invalid version for command protocol!\n");
+		return 1;
+	}
+
+	if (google_chromeec_wait_ready(EC_LPC_ADDR_HOST_CMD)) {
+		printk(BIOS_ERR, "Timeout waiting for EC ready!\n");
+		return 1;
+	}
+
+	/* Copy command data, if any. */
+	for (i = 0; i < cec_command->cmd_size_in; i++)
+		outb(((char*)cec_command->cmd_data_in)[i],
+		     EC_LPC_ADDR_OLD_PARAM + i);
+
+	/* Issue the command. */
+	outb(cec_command->cmd_code, EC_LPC_ADDR_HOST_CMD);
+
+	if (google_chromeec_wait_ready(EC_LPC_ADDR_HOST_CMD)) {
+		printk(BIOS_ERR, "Timeout waiting for EC process command %d!\n",
+		       cec_command->cmd_code);
+		return 1;
+	}
+
+	for (i = 0; i < cec_command->cmd_size_out; i++)
+		((char*)cec_command->cmd_data_out)[i] =
+			inb(EC_LPC_ADDR_OLD_PARAM + i);
+	cec_command->cmd_code = inb(EC_LPC_ADDR_HOST_DATA);
+	return 0;
+}
+
+int google_chromeec_command(struct chromeec_command *cec_command)
+{
+	struct ec_lpc_host_args args;
+	const u8 *d;
+	u8 *dout;
+	u8 cmd_code = cec_command->cmd_code;
+	int csum;
+	int i;
+
+	/* Fall back to old command protocol if necessary */
+	if (!google_chromeec_cmd_args_supported())
+		return google_chromeec_command_old(cec_command);
+
+	/* Fill in args */
+	args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
+	args.command_version = cec_command->cmd_version;
+	args.data_size = cec_command->cmd_size_in;
+
+	/* Initialize checksum */
+	csum = cmd_code + args.flags + args.command_version + args.data_size;
+
+	/* Write data and update checksum */
+	for (i = 0, d = (const u8 *)cec_command->cmd_data_in;
+	     i < cec_command->cmd_size_in; i++, d++) {
+		outb(*d, EC_LPC_ADDR_HOST_PARAM + i);
+		csum += *d;
+	}
+
+	/* Finalize checksum and write args */
+	args.checksum = (u8)csum;
+	for (i = 0, d = (const u8 *)&args; i < sizeof(args); i++, d++)
+		outb(*d, EC_LPC_ADDR_HOST_ARGS + i);
+
+
+	/* Issue the command */
+	outb(cmd_code, EC_LPC_ADDR_HOST_CMD);
+
+	if (google_chromeec_wait_ready(EC_LPC_ADDR_HOST_CMD)) {
+		printk(BIOS_ERR, "Timeout waiting for EC process command %d!\n",
+		       cec_command->cmd_code);
+		return 1;
+	}
+
+	/* Check result */
+	cec_command->cmd_code = inb(EC_LPC_ADDR_HOST_DATA);
+	if (cec_command->cmd_code)
+		return 1;
+
+	/* Read back args */
+	for (i = 0, dout = (u8 *)&args; i < sizeof(args); i++, dout++)
+		*dout = inb(EC_LPC_ADDR_HOST_ARGS + i);
+
+	/*
+	 * If EC didn't modify args flags, then somehow we sent a new-style
+	 * command to an old EC, which means it would have read its params
+	 * from the wrong place.
+	 */
+	if (!(args.flags & EC_HOST_ARGS_FLAG_TO_HOST)) {
+		printk(BIOS_ERR, "EC protocol mismatch\n");
+		return 1;
+	}
+
+	if (args.data_size > cec_command->cmd_size_out) {
+		printk(BIOS_ERR, "EC returned too much data\n");
+		return 1;
+	}
+	cec_command->cmd_size_out = args.data_size;
+
+	/* Start calculating response checksum */
+	csum = cmd_code + args.flags + args.command_version + args.data_size;
+
+	/* Read data, if any */
+	for (i = 0, dout = (u8 *)cec_command->cmd_data_out;
+	     i < args.data_size; i++, dout++) {
+		*dout = inb(EC_LPC_ADDR_HOST_PARAM + i);
+		csum += *dout;
+	}
+
+	/* Verify checksum */
+	if (args.checksum != (u8)csum) {
+		printk(BIOS_ERR, "EC response has invalid checksum\n");
+		return 1;
+	}
+
+	return 0;
+}
+
+#ifndef __PRE_RAM__
+u8 google_chromeec_get_event(void)
+{
+	if (google_chromeec_wait_ready(EC_LPC_ADDR_ACPI_CMD)) {
+		printk(BIOS_ERR, "Timeout waiting for EC ready!\n");
+		return 1;
+	}
+
+	/* Issue the ACPI query-event command */
+	outb(EC_CMD_ACPI_QUERY_EVENT, EC_LPC_ADDR_ACPI_CMD);
+
+	if (google_chromeec_wait_ready(EC_LPC_ADDR_ACPI_CMD)) {
+		printk(BIOS_ERR, "Timeout waiting for EC QUERY_EVENT!\n");
+		return 0;
+	}
+
+	/* Event (or 0 if none) is returned directly in the data byte */
+	return inb(EC_LPC_ADDR_ACPI_DATA);
+}
+#endif