cros: add LPC support for cros_ec

This patch adds LPC support for carrying out the cros_ec protocol.

Signed-off-by: Randall Spangler <rspangler@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Hung-ying Tyan <tyanh@chromium.org>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>

1 files changed, 283 insertions, 0 deletions

diff --git a/drivers/misc/cros_ec_lpc.c b/drivers/misc/cros_ec_lpc.c
new file mode 100644
index 0000000..cf0435b
--- /dev/null
+++ b/drivers/misc/cros_ec_lpc.c
@@ -0,0 +1,283 @@
+/*
+ * Chromium OS cros_ec driver - LPC interface
+ *
+ * Copyright (c) 2012 The Chromium OS Authors.
+ * See file CREDITS for list of people who contributed to this
+ * project.
+ *
+ * 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; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * 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., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+/*
+ * The Matrix Keyboard Protocol driver handles talking to the keyboard
+ * controller chip. Mostly this is for keyboard functions, but some other
+ * things have slipped in, so we provide generic services to talk to the
+ * KBC.
+ */
+
+#include <common.h>
+#include <command.h>
+#include <cros_ec.h>
+#include <asm/io.h>
+
+#ifdef DEBUG_TRACE
+#define debug_trace(fmt, b...)	debug(fmt, ##b)
+#else
+#define debug_trace(fmt, b...)
+#endif
+
+static int wait_for_sync(struct cros_ec_dev *dev)
+{
+	unsigned long start;
+
+	start = get_timer(0);
+	while (inb(EC_LPC_ADDR_HOST_CMD) & EC_LPC_STATUS_BUSY_MASK) {
+		if (get_timer(start) > 1000) {
+			debug("%s: Timeout waiting for CROS_EC sync\n",
+			      __func__);
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * Send a command to a LPC CROS_EC device and return the reply.
+ *
+ * The device's internal input/output buffers are used.
+ *
+ * @param dev		CROS_EC device
+ * @param cmd		Command to send (EC_CMD_...)
+ * @param cmd_version	Version of command to send (EC_VER_...)
+ * @param dout          Output data (may be NULL If dout_len=0)
+ * @param dout_len      Size of output data in bytes
+ * @param dinp          Place to put pointer to response data
+ * @param din_len       Maximum size of response in bytes
+ * @return number of bytes in response, or -1 on error
+ */
+static int old_lpc_command(struct cros_ec_dev *dev, uint8_t cmd,
+		     const uint8_t *dout, int dout_len,
+		     uint8_t **dinp, int din_len)
+{
+	int ret, i;
+
+	if (dout_len > EC_OLD_PARAM_SIZE) {
+		debug("%s: Cannot send %d bytes\n", __func__, dout_len);
+		return -1;
+	}
+
+	if (din_len > EC_OLD_PARAM_SIZE) {
+		debug("%s: Cannot receive %d bytes\n", __func__, din_len);
+		return -1;
+	}
+
+	if (wait_for_sync(dev)) {
+		debug("%s: Timeout waiting ready\n", __func__);
+		return -1;
+	}
+
+	debug_trace("cmd: %02x, ", cmd);
+	for (i = 0; i < dout_len; i++) {
+		debug_trace("%02x ", dout[i]);
+		outb(dout[i], EC_LPC_ADDR_OLD_PARAM + i);
+	}
+	outb(cmd, EC_LPC_ADDR_HOST_CMD);
+	debug_trace("\n");
+
+	if (wait_for_sync(dev)) {
+		debug("%s: Timeout waiting ready\n", __func__);
+		return -1;
+	}
+
+	ret = inb(EC_LPC_ADDR_HOST_DATA);
+	if (ret) {
+		debug("%s: CROS_EC result code %d\n", __func__, ret);
+		return -ret;
+	}
+
+	debug_trace("resp: %02x, ", ret);
+	for (i = 0; i < din_len; i++) {
+		dev->din[i] = inb(EC_LPC_ADDR_OLD_PARAM + i);
+		debug_trace("%02x ", dev->din[i]);
+	}
+	debug_trace("\n");
+	*dinp = dev->din;
+
+	return din_len;
+}
+
+int cros_ec_lpc_command(struct cros_ec_dev *dev, uint8_t cmd, int cmd_version,
+		     const uint8_t *dout, int dout_len,
+		     uint8_t **dinp, int din_len)
+{
+	const int cmd_addr = EC_LPC_ADDR_HOST_CMD;
+	const int data_addr = EC_LPC_ADDR_HOST_DATA;
+	const int args_addr = EC_LPC_ADDR_HOST_ARGS;
+	const int param_addr = EC_LPC_ADDR_HOST_PARAM;
+
+	struct ec_lpc_host_args args;
+	uint8_t *d;
+	int csum;
+	int i;
+
+	/* Fall back to old-style command interface if args aren't supported */
+	if (!dev->cmd_version_is_supported)
+		return old_lpc_command(dev, cmd, dout, dout_len, dinp,
+				       din_len);
+
+	if (dout_len > EC_HOST_PARAM_SIZE) {
+		debug("%s: Cannot send %d bytes\n", __func__, dout_len);
+		return -1;
+	}
+
+	/* Fill in args */
+	args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
+	args.command_version = cmd_version;
+	args.data_size = dout_len;
+
+	/* Calculate checksum */
+	csum = cmd + args.flags + args.command_version + args.data_size;
+	for (i = 0, d = (uint8_t *)dout; i < dout_len; i++, d++)
+		csum += *d;
+
+	args.checksum = (uint8_t)csum;
+
+	if (wait_for_sync(dev)) {
+		debug("%s: Timeout waiting ready\n", __func__);
+		return -1;
+	}
+
+	/* Write args */
+	for (i = 0, d = (uint8_t *)&args; i < sizeof(args); i++, d++)
+		outb(*d, args_addr + i);
+
+	/* Write data, if any */
+	debug_trace("cmd: %02x, ver: %02x", cmd, cmd_version);
+	for (i = 0, d = (uint8_t *)dout; i < dout_len; i++, d++) {
+		outb(*d, param_addr + i);
+		debug_trace("%02x ", *d);
+	}
+
+	outb(cmd, cmd_addr);
+	debug_trace("\n");
+
+	if (wait_for_sync(dev)) {
+		debug("%s: Timeout waiting for response\n", __func__);
+		return -1;
+	}
+
+	/* Check result */
+	i = inb(data_addr);
+	if (i) {
+		debug("%s: CROS_EC result code %d\n", __func__, i);
+		return -i;
+	}
+
+	/* Read back args */
+	for (i = 0, d = (uint8_t *)&args; i < sizeof(args); i++, d++)
+		*d = inb(args_addr + 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)) {
+		debug("%s: CROS_EC protocol mismatch\n", __func__);
+		return -EC_RES_INVALID_RESPONSE;
+	}
+
+	if (args.data_size > din_len) {
+		debug("%s: CROS_EC returned too much data %d > %d\n",
+		      __func__, args.data_size, din_len);
+		return -EC_RES_INVALID_RESPONSE;
+	}
+
+	/* Read data, if any */
+	for (i = 0, d = (uint8_t *)dev->din; i < args.data_size; i++, d++) {
+		*d = inb(param_addr + i);
+		debug_trace("%02x ", *d);
+	}
+	debug_trace("\n");
+
+	/* Verify checksum */
+	csum = cmd + args.flags + args.command_version + args.data_size;
+	for (i = 0, d = (uint8_t *)dev->din; i < args.data_size; i++, d++)
+		csum += *d;
+
+	if (args.checksum != (uint8_t)csum) {
+		debug("%s: CROS_EC response has invalid checksum\n", __func__);
+		return -EC_RES_INVALID_CHECKSUM;
+	}
+	*dinp = dev->din;
+
+	/* Return actual amount of data received */
+	return args.data_size;
+}
+
+/**
+ * Initialize LPC protocol.
+ *
+ * @param dev		CROS_EC device
+ * @param blob		Device tree blob
+ * @return 0 if ok, -1 on error
+ */
+int cros_ec_lpc_init(struct cros_ec_dev *dev, const void *blob)
+{
+	int byte, i;
+
+	/* See if we can find an EC at the other end */
+	byte = 0xff;
+	byte &= inb(EC_LPC_ADDR_HOST_CMD);
+	byte &= inb(EC_LPC_ADDR_HOST_DATA);
+	for (i = 0; i < EC_HOST_PARAM_SIZE && (byte == 0xff); i++)
+		byte &= inb(EC_LPC_ADDR_HOST_PARAM + i);
+	if (byte == 0xff) {
+		debug("%s: CROS_EC device not found on LPC bus\n",
+			__func__);
+		return -1;
+	}
+
+	return 0;
+}
+
+/*
+ * Test if LPC command args are supported.
+ *
+ * The cheapest way to do this is by looking for the memory-mapped
+ * flag.  This is faster than sending a new-style 'hello' command and
+ * seeing whether the EC sets the EC_HOST_ARGS_FLAG_FROM_HOST flag
+ * in args when it responds.
+ */
+int cros_ec_lpc_check_version(struct cros_ec_dev *dev)
+{
+	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)) {
+		dev->cmd_version_is_supported = 1;
+	} else {
+		/* We are going to use the old IO ports */
+		dev->cmd_version_is_supported = 0;
+	}
+	debug("lpc: version %s\n", dev->cmd_version_is_supported ?
+			"new" : "old");
+
+	return 0;
+}