ec/google: Support ChromeOS EC on SPI bus.

For devices with ChromeOS EC on SPI bus, use the standard SPI driver interface
(see spi-generic.h) to exchange data.

Note: Only EC protocol v3 is supported for SPI bus.

Change-Id: Ia8dcdecd125a2bd7424d0c7560e046b6d6988a03
Signed-off-by: Hung-Te Lin <hungte@chromium.org>
Reviewed-on: http://review.coreboot.org/3751
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/ec/google/chromeec/Kconfig

@@ -22,7 +22,21 @@ config EC_GOOGLE_CHROMEEC_I2C_CHIP
 
 config EC_GOOGLE_CHROMEEC_LPC
         depends on EC_GOOGLE_CHROMEEC && ARCH_X86  # Needs Plug-and-play.
-	bool
-	default y
+	def_bool y
 	help
 	  Google Chrome EC via LPC bus.
+
+config EC_GOOGLE_CHROMEEC_SPI
+	depends on EC_GOOGLE_CHROMEEC
+	def_bool n
+	help
+	  Google's Chrome EC via SPI bus.
+
+config EC_GOOGLE_CHROMEEC_SPI_BUS
+	depends on EC_GOOGLE_CHROMEEC_SPI
+	hex "SPI bus for Google's Chrome EC"
+
+config EC_GOOGLE_CHROMEEC_SPI_CHIP
+	depends on EC_GOOGLE_CHROMEEC_SPI
+	hex
+	default 0

src/ec/google/chromeec/Makefile.inc

@@ -1,9 +1,12 @@
 ramstage-y += ec.c crosec_proto.c
 ramstage-$(CONFIG_EC_GOOGLE_CHROMEEC_I2C) += ec_i2c.c
 ramstage-$(CONFIG_EC_GOOGLE_CHROMEEC_LPC) += ec_lpc.c
+ramstage-$(CONFIG_EC_GOOGLE_CHROMEEC_SPI) += ec_spi.c
 smm-y += ec.c crosec_proto.c
 smm-$(CONFIG_EC_GOOGLE_CHROMEEC_I2C) += ec_i2c.c
 smm-$(CONFIG_EC_GOOGLE_CHROMEEC_LPC) += ec_lpc.c
+smm-$(CONFIG_EC_GOOGLE_CHROMEEC_SPI) += ec_spi.c
 romstage-y += ec.c crosec_proto.c
 romstage-$(CONFIG_EC_GOOGLE_CHROMEEC_I2C) += ec_i2c.c
 romstage-$(CONFIG_EC_GOOGLE_CHROMEEC_LPC) += ec_lpc.c
+romstage-$(CONFIG_EC_GOOGLE_CHROMEEC_SPI) += ec_spi.c

src/ec/google/chromeec/ec_spi.c

@@ -0,0 +1,65 @@
+/*
+ * 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 <console/console.h>
+#include <spi-generic.h>
+#include "ec.h"
+#include "ec_commands.h"
+
+#define CROSEC_SPI_SPEED	(500000)
+
+static int crosec_spi_io(uint8_t *write_bytes, size_t write_size,
+			 uint8_t *read_bytes, size_t read_size,
+			 void *context)
+{
+	struct spi_slave *slave = (struct spi_slave *)context;
+	int rv;
+
+	spi_claim_bus(slave);
+	rv = spi_xfer(slave, write_bytes, write_size * 8, read_bytes,
+		      read_size * 8);
+	spi_release_bus(slave);
+
+	if (rv != 0) {
+		printk(BIOS_ERR, "%s: Cannot complete SPI I/O\n", __func__);
+		return -1;
+	}
+
+	return 0;
+}
+
+int google_chromeec_command(struct chromeec_command *cec_command)
+{
+	static struct spi_slave *slave = NULL;
+	if (!slave) {
+		slave = spi_setup_slave(CONFIG_EC_GOOGLE_CHROMEEC_SPI_BUS,
+					CONFIG_EC_GOOGLE_CHROMEEC_SPI_CHIP,
+					CROSEC_SPI_SPEED,
+					SPI_READ_FLAG | SPI_WRITE_FLAG);
+	}
+	return crosec_command_proto(cec_command, crosec_spi_io, slave);
+}
+
+#ifndef __PRE_RAM__
+u8 google_chromeec_get_event(void)
+{
+	printk(BIOS_ERR, "%s: Not supported.\n", __func__);
+	return 0;
+}
+#endif