chromeec: lpc: Add variant MEC IO

MEC cannot access memmap-range data directly though LPC and instead must
access through its EMI unit.

BUG=chrome-os-partner:38224
TEST=Verify host command functionality on glower.
BRANCH=None

Change-Id: If98d425014a894ddeafad4268f92af5860878522
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: 58ed3c50ab97ca1e172d5cdc00f4cd8e069e565c
Original-Change-Id: I32b897836d28ef4f3b3aa5f81b9023f2ceb629c8
Original-Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/263611
Original-Reviewed-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: http://review.coreboot.org/9910
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/ec/google/chromeec/Kconfig

@@ -41,6 +41,12 @@ config EC_GOOGLE_CHROMEEC_LPC
 	help
 	  Google Chrome EC via LPC bus.
 
+config EC_GOOGLE_CHROMEEC_MEC
+	depends on EC_GOOGLE_CHROMEEC_LPC
+	def_bool n
+	help
+	  Microchip EC variant for LPC register access.
+
 config EC_GOOGLE_CHROMEEC_SPI
 	depends on EC_GOOGLE_CHROMEEC
 	def_bool n

src/ec/google/chromeec/Makefile.inc

@@ -1,19 +1,23 @@
 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-$(CONFIG_EC_GOOGLE_CHROMEEC_MEC) += ec_mec.c
 ramstage-$(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-$(CONFIG_EC_GOOGLE_CHROMEEC_MEC) += ec_mec.c
 smm-$(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-$(CONFIG_EC_GOOGLE_CHROMEEC_MEC) += ec_mec.c
 romstage-$(CONFIG_EC_GOOGLE_CHROMEEC_SPI) += ec_spi.c
 ifeq ($(CONFIG_VBOOT2_VERIFY_FIRMWARE),y)
 verstage-y += ec.c crosec_proto.c
 verstage-$(CONFIG_EC_GOOGLE_CHROMEEC_I2C) += ec_i2c.c
 verstage-$(CONFIG_EC_GOOGLE_CHROMEEC_LPC) += ec_lpc.c
+verstage-$(CONFIG_EC_GOOGLE_CHROMEEC_MEC) += ec_mec.c
 verstage-$(CONFIG_EC_GOOGLE_CHROMEEC_SPI) += ec_spi.c
 endif
 

src/ec/google/chromeec/ec.h

@@ -54,6 +54,13 @@ void google_chromeec_post(u8 postcode);
 void google_chromeec_log_events(u32 mask);
 int google_chromeec_vbnv_context(int is_read, uint8_t *data, int len);
 
+/* For MEC, access ranges 0x800 thru 0x9ff using EMI interface instead of LPC */
+#define MEC_EMI_RANGE_START EC_HOST_CMD_REGION0
+#define MEC_EMI_RANGE_END   (EC_LPC_ADDR_MEMMAP + EC_MEMMAP_SIZE)
+
+void mec_io_bytes(int write, u16 offset, unsigned int length,
+		  u8 *buf, u8 *csum);
+
 enum usb_charge_mode {
 	USB_CHARGE_MODE_DISABLED,
 	USB_CHARGE_MODE_CHARGE_AUTO,

src/ec/google/chromeec/ec_lpc.c

@@ -41,6 +41,14 @@ static void read_bytes(u16 port, unsigned int length, u8 *dest, u8 *csum)
 {
 	int i;
 
+#if CONFIG_EC_GOOGLE_CHROMEEC_MEC
+	/* Access desired range though EMI interface */
+	if (port >= MEC_EMI_RANGE_START && port <= MEC_EMI_RANGE_END) {
+		mec_io_bytes(0, port, length, dest, csum);
+		return;
+	}
+#endif
+
 	for (i = 0; i < length; ++i) {
 		dest[i] = inb(port + i);
 		if (csum)
@@ -68,6 +76,14 @@ static void write_bytes(u16 port, unsigned int length, u8 *msg, u8 *csum)
 {
 	int i;
 
+#if CONFIG_EC_GOOGLE_CHROMEEC_MEC
+	/* Access desired range though EMI interface */
+	if (port >= MEC_EMI_RANGE_START && port <= MEC_EMI_RANGE_END) {
+		mec_io_bytes(1, port, length, msg, csum);
+		return;
+	}
+#endif
+
 	for (i = 0; i < length; ++i) {
 		outb(msg[i], port + i);
 		if (csum)

src/ec/google/chromeec/ec_mec.c

@@ -0,0 +1,105 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2015 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 <arch/io.h>
+#include "ec.h"
+#include "ec_commands.h"
+
+enum {
+	/* 8-bit access */
+	ACCESS_TYPE_BYTE = 0x0,
+	/* 16-bit access */
+	ACCESS_TYPE_WORD = 0x1,
+	/* 32-bit access */
+	ACCESS_TYPE_LONG = 0x2,
+	/*
+	 * 32-bit access, read or write of MEC_EMI_EC_DATA_B3 causes the
+	 * EC data register to be incremented.
+	 */
+	ACCESS_TYPE_LONG_AUTO_INCREMENT = 0x3,
+};
+
+/* EMI registers are relative to base */
+#define MEC_EMI_BASE		0x800
+#define MEC_EMI_HOST_TO_EC	(MEC_EMI_BASE + 0)
+#define MEC_EMI_EC_TO_HOST	(MEC_EMI_BASE + 1)
+#define MEC_EMI_EC_ADDRESS_B0	(MEC_EMI_BASE + 2)
+#define MEC_EMI_EC_ADDRESS_B1	(MEC_EMI_BASE + 3)
+#define MEC_EMI_EC_DATA_B0	(MEC_EMI_BASE + 4)
+#define MEC_EMI_EC_DATA_B1	(MEC_EMI_BASE + 5)
+#define MEC_EMI_EC_DATA_B2 	(MEC_EMI_BASE + 6)
+#define MEC_EMI_EC_DATA_B3	(MEC_EMI_BASE + 7)
+
+/*
+ * cros_ec_lpc_mec_emi_write_address
+ *
+ * Initialize EMI read / write at a given address.
+ *
+ * @addr:        Starting read / write address
+ * @access_mode: Type of access, typically 32-bit auto-increment
+ */
+static void mec_emi_write_address(u16 addr, u8 access_mode)
+{
+	/* Address relative to start of EMI range */
+	addr -= MEC_EMI_RANGE_START;
+	outb((addr & 0xfc) | access_mode, MEC_EMI_EC_ADDRESS_B0);
+	outb((addr >> 8) & 0x7f, MEC_EMI_EC_ADDRESS_B1);
+}
+
+/*
+ * mec_io_bytes - Read / write bytes to MEC EMI port
+ *
+ * @write:   1 on write operation, 0 on read
+ * @port:    Base read / write address
+ * @length:  Number of bytes to read / write
+ * @buf:     Destination / source buffer
+ * @csum:    Optional parameter, sums data transferred
+ *
+ */
+void mec_io_bytes(int write, u16 port, unsigned int length, u8 *buf, u8 *csum)
+{
+	int i = 0;
+	int io_addr;
+
+	if (length == 0)
+		return;
+
+	/* Initialize I/O at desired address */
+	mec_emi_write_address(port, ACCESS_TYPE_LONG_AUTO_INCREMENT);
+
+	/* Skip bytes in case of misaligned port */
+	io_addr = MEC_EMI_EC_DATA_B0 + (port & 0x3);
+	while (i < length) {
+		while (io_addr <= MEC_EMI_EC_DATA_B3) {
+			if (write)
+				outb(buf[i], io_addr++);
+			else
+				buf[i] = inb(io_addr++);
+			if (csum)
+				*csum += buf[i];
+
+			/* Extra bounds check in case of misaligned length */
+			if (++i == length)
+				return;
+		}
+
+		/* Access [B0, B3] on each loop pass */
+		io_addr = MEC_EMI_EC_DATA_B0;
+	}
+}