platform/chrome: cros_ec_lpc: Add R/W helpers to LPC protocol variants

Call common functions for read / write to prepare support for future
LPC protocol variants which use different I/O ops than inb / outb.

Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Benson Leung <bleung@chromium.org>

drivers/platform/chrome/Makefile

@@ -5,6 +5,7 @@ cros_ec_devs-objs			:= cros_ec_dev.o cros_ec_sysfs.o \
 					   cros_ec_lightbar.o cros_ec_vbc.o \
 					   cros_ec_debugfs.o
 obj-$(CONFIG_CROS_EC_CHARDEV)		+= cros_ec_devs.o
-obj-$(CONFIG_CROS_EC_LPC)		+= cros_ec_lpc.o
+cros_ec_lpcs-objs			:= cros_ec_lpc.o cros_ec_lpc_reg.o
+obj-$(CONFIG_CROS_EC_LPC)		+= cros_ec_lpcs.o
 obj-$(CONFIG_CROS_EC_PROTO)		+= cros_ec_proto.o
 obj-$(CONFIG_CROS_KBD_LED_BACKLIGHT)	+= cros_kbd_led_backlight.o

drivers/platform/chrome/cros_ec_lpc.c

@@ -26,19 +26,22 @@
 #include <linux/io.h>
 #include <linux/mfd/cros_ec.h>
 #include <linux/mfd/cros_ec_commands.h>
+#include <linux/mfd/cros_ec_lpc_reg.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/printk.h>
 
-#define DRV_NAME "cros_ec_lpc"
+#define DRV_NAME "cros_ec_lpcs"
 
 static int ec_response_timed_out(void)
 {
 	unsigned long one_second = jiffies + HZ;
+	u8 data;
 
 	usleep_range(200, 300);
 	do {
-		if (!(inb(EC_LPC_ADDR_HOST_CMD) & EC_LPC_STATUS_BUSY_MASK))
+		if (!(cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_CMD, 1, &data) &
+		    EC_LPC_STATUS_BUSY_MASK))
 			return 0;
 		usleep_range(100, 200);
 	} while (time_before(jiffies, one_second));
@@ -51,21 +54,20 @@ static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
 {
 	struct ec_host_request *request;
 	struct ec_host_response response;
-	u8 sum = 0;
-	int i;
+	u8 sum;
 	int ret = 0;
 	u8 *dout;
 
 	ret = cros_ec_prepare_tx(ec, msg);
 
 	/* Write buffer */
-	for (i = 0; i < ret; i++)
-		outb(ec->dout[i], EC_LPC_ADDR_HOST_PACKET + i);
+	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PACKET, ret, ec->dout);
 
 	request = (struct ec_host_request *)ec->dout;
 
 	/* Here we go */
-	outb(EC_COMMAND_PROTOCOL_3, EC_LPC_ADDR_HOST_CMD);
+	sum = EC_COMMAND_PROTOCOL_3;
+	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_CMD, 1, &sum);
 
 	if (ec_response_timed_out()) {
 		dev_warn(ec->dev, "EC responsed timed out\n");
@@ -74,17 +76,15 @@ static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
 	}
 
 	/* Check result */
-	msg->result = inb(EC_LPC_ADDR_HOST_DATA);
+	msg->result = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_DATA, 1, &sum);
 	ret = cros_ec_check_result(ec, msg);
 	if (ret)
 		goto done;
 
 	/* Read back response */
 	dout = (u8 *)&response;
-	for (i = 0; i < sizeof(response); i++) {
-		dout[i] = inb(EC_LPC_ADDR_HOST_PACKET + i);
-		sum += dout[i];
-	}
+	sum = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET, sizeof(response),
+				     dout);
 
 	msg->result = response.result;
 
@@ -97,11 +97,9 @@ static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
 	}
 
 	/* Read response and process checksum */
-	for (i = 0; i < response.data_len; i++) {
-		msg->data[i] =
-			inb(EC_LPC_ADDR_HOST_PACKET + sizeof(response) + i);
-		sum += msg->data[i];
-	}
+	sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET +
+				      sizeof(response), response.data_len,
+				      msg->data);
 
 	if (sum) {
 		dev_err(ec->dev,
@@ -121,8 +119,7 @@ static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
 				struct cros_ec_command *msg)
 {
 	struct ec_lpc_host_args args;
-	int csum;
-	int i;
+	u8 sum;
 	int ret = 0;
 
 	if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE ||
@@ -139,24 +136,20 @@ static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
 	args.data_size = msg->outsize;
 
 	/* Initialize checksum */
-	csum = msg->command + args.flags +
-		args.command_version + args.data_size;
+	sum = msg->command + args.flags + args.command_version + args.data_size;
 
 	/* Copy data and update checksum */
-	for (i = 0; i < msg->outsize; i++) {
-		outb(msg->data[i], EC_LPC_ADDR_HOST_PARAM + i);
-		csum += msg->data[i];
-	}
+	sum += cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PARAM, msg->outsize,
+				       msg->data);
 
 	/* Finalize checksum and write args */
-	args.checksum = csum & 0xFF;
-	outb(args.flags, EC_LPC_ADDR_HOST_ARGS);
-	outb(args.command_version, EC_LPC_ADDR_HOST_ARGS + 1);
-	outb(args.data_size, EC_LPC_ADDR_HOST_ARGS + 2);
-	outb(args.checksum, EC_LPC_ADDR_HOST_ARGS + 3);
+	args.checksum = sum;
+	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
+				(u8 *)&args);
 
 	/* Here we go */
-	outb(msg->command, EC_LPC_ADDR_HOST_CMD);
+	sum = msg->command;
+	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_CMD, 1, &sum);
 
 	if (ec_response_timed_out()) {
 		dev_warn(ec->dev, "EC responsed timed out\n");
@@ -165,16 +158,14 @@ static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
 	}
 
 	/* Check result */
-	msg->result = inb(EC_LPC_ADDR_HOST_DATA);
+	msg->result = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_DATA, 1, &sum);
 	ret = cros_ec_check_result(ec, msg);
 	if (ret)
 		goto done;
 
 	/* Read back args */
-	args.flags = inb(EC_LPC_ADDR_HOST_ARGS);
-	args.command_version = inb(EC_LPC_ADDR_HOST_ARGS + 1);
-	args.data_size = inb(EC_LPC_ADDR_HOST_ARGS + 2);
-	args.checksum = inb(EC_LPC_ADDR_HOST_ARGS + 3);
+	cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
+			       (u8 *)&args);
 
 	if (args.data_size > msg->insize) {
 		dev_err(ec->dev,
@@ -185,20 +176,17 @@ static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
 	}
 
 	/* Start calculating response checksum */
-	csum = msg->command + args.flags +
-		args.command_version + args.data_size;
+	sum = msg->command + args.flags + args.command_version + args.data_size;
 
 	/* Read response and update checksum */
-	for (i = 0; i < args.data_size; i++) {
-		msg->data[i] = inb(EC_LPC_ADDR_HOST_PARAM + i);
-		csum += msg->data[i];
-	}
+	sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PARAM, args.data_size,
+				      msg->data);
 
 	/* Verify checksum */
-	if (args.checksum != (csum & 0xFF)) {
+	if (args.checksum != sum) {
 		dev_err(ec->dev,
 			"bad packet checksum, expected %02x, got %02x\n",
-			args.checksum, csum & 0xFF);
+			args.checksum, sum);
 		ret = -EBADMSG;
 		goto done;
 	}
@@ -222,14 +210,13 @@ static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
 
 	/* fixed length */
 	if (bytes) {
-		for (; cnt < bytes; i++, s++, cnt++)
-			*s = inb(EC_LPC_ADDR_MEMMAP + i);
-		return cnt;
+		cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + offset, bytes, s);
+		return bytes;
 	}
 
 	/* string */
 	for (; i < EC_MEMMAP_SIZE; i++, s++) {
-		*s = inb(EC_LPC_ADDR_MEMMAP + i);
+		cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + i, 1, s);
 		cnt++;
 		if (!*s)
 			break;
@@ -242,6 +229,7 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct cros_ec_device *ec_dev;
+	u8 buf[2];
 	int ret;
 
 	if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
@@ -250,8 +238,8 @@ static int cros_ec_lpc_probe(struct platform_device *pdev)
 		return -EBUSY;
 	}
 
-	if ((inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID) != 'E') ||
-	    (inb(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID + 1) != 'C')) {
+	cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + EC_MEMMAP_ID, 2, buf);
+	if (buf[0] != 'E' || buf[1] != 'C') {
 		dev_err(dev, "EC ID not detected\n");
 		return -ENODEV;
 	}

drivers/platform/chrome/cros_ec_lpc_reg.c

@@ -0,0 +1,64 @@
+/*
+ * cros_ec_lpc_reg - LPC access to the Chrome OS Embedded Controller
+ *
+ * Copyright (C) 2016 Google, Inc
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ * This driver uses the Chrome OS EC byte-level message-based protocol for
+ * communicating the keyboard state (which keys are pressed) from a keyboard EC
+ * to the AP over some bus (such as i2c, lpc, spi).  The EC does debouncing,
+ * but everything else (including deghosting) is done here.  The main
+ * motivation for this is to keep the EC firmware as simple as possible, since
+ * it cannot be easily upgraded and EC flash/IRAM space is relatively
+ * expensive.
+ */
+
+#include <linux/io.h>
+#include <linux/mfd/cros_ec.h>
+#include <linux/mfd/cros_ec_commands.h>
+
+static u8 lpc_read_bytes(unsigned int offset, unsigned int length, u8 *dest)
+{
+	int i;
+	int sum = 0;
+
+	for (i = 0; i < length; ++i) {
+		dest[i] = inb(offset + i);
+		sum += dest[i];
+	}
+
+	/* Return checksum of all bytes read */
+	return sum;
+}
+
+static u8 lpc_write_bytes(unsigned int offset, unsigned int length, u8 *msg)
+{
+	int i;
+	int sum = 0;
+
+	for (i = 0; i < length; ++i) {
+		outb(msg[i], offset + i);
+		sum += msg[i];
+	}
+
+	/* Return checksum of all bytes written */
+	return sum;
+}
+
+u8 cros_ec_lpc_read_bytes(unsigned int offset, unsigned int length, u8 *dest)
+{
+	return lpc_read_bytes(offset, length, dest);
+}
+
+u8 cros_ec_lpc_write_bytes(unsigned int offset, unsigned int length, u8 *msg)
+{
+	return lpc_write_bytes(offset, length, msg);
+}

include/linux/mfd/cros_ec_lpc_reg.h

@@ -0,0 +1,47 @@
+/*
+ * cros_ec_lpc_reg - LPC access to the Chrome OS Embedded Controller
+ *
+ * Copyright (C) 2016 Google, Inc
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ * This driver uses the Chrome OS EC byte-level message-based protocol for
+ * communicating the keyboard state (which keys are pressed) from a keyboard EC
+ * to the AP over some bus (such as i2c, lpc, spi).  The EC does debouncing,
+ * but everything else (including deghosting) is done here.  The main
+ * motivation for this is to keep the EC firmware as simple as possible, since
+ * it cannot be easily upgraded and EC flash/IRAM space is relatively
+ * expensive.
+ */
+
+#ifndef __LINUX_MFD_CROS_EC_REG_H
+#define __LINUX_MFD_CROS_EC_REG_H
+
+/**
+ * cros_ec_lpc_read_bytes - Read bytes from a given LPC-mapped address.
+ * Returns 8-bit checksum of all bytes read.
+ *
+ * @offset: Base read address
+ * @length: Number of bytes to read
+ * @dest: Destination buffer
+ */
+u8 cros_ec_lpc_read_bytes(unsigned int offset, unsigned int length, u8 *dest);
+
+/**
+ * cros_ec_lpc_write_bytes - Write bytes to a given LPC-mapped address.
+ * Returns 8-bit checksum of all bytes written.
+ *
+ * @offset: Base write address
+ * @length: Number of bytes to write
+ * @msg: Write data buffer
+ */
+u8 cros_ec_lpc_write_bytes(unsigned int offset, unsigned int length, u8 *msg);
+
+#endif /* __LINUX_MFD_CROS_EC_REG_H */