drivers/platform/chrome/cros_ec_lpc.c - pub/scm/linux/kernel/git/jkirsher/next-queue - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 // LPC interface for ChromeOS Embedded Controller
 //
 // Copyright (C) 2012-2015 Google, Inc
 //
 // This driver uses the ChromeOS 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/acpi.h>
 #include <linux/dmi.h>
 #include <linux/delay.h>
 #include <linux/io.h>
 #include <linux/interrupt.h>
 #include <linux/mfd/cros_ec.h>
 #include <linux/mfd/cros_ec_commands.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/printk.h>
 #include <linux/suspend.h>

 #include "cros_ec_lpc_reg.h"

 #define DRV_NAME "cros_ec_lpcs"
 #define ACPI_DRV_NAME "GOOG0004"

 /* True if ACPI device is present */
 static bool cros_ec_lpc_acpi_device_found;

 static int ec_response_timed_out(void)
 {
 	unsigned long one_second = jiffies + HZ;
 	u8 data;

 	usleep_range(200, 300);
 	do {
 		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));

 	return 1;
 }

 static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
 				struct cros_ec_command *msg)
 {
 	struct ec_host_response response;
 	u8 sum;
 	int ret = 0;
 	u8 *dout;

 	ret = cros_ec_prepare_tx(ec, msg);

 	/* Write buffer */
 	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PACKET, ret, ec->dout);

 	/* Here we go */
 	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");
 		ret = -EIO;
 		goto done;
 	}

 	/* Check result */
 	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;
 	sum = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET, sizeof(response),
 				     dout);

 	msg->result = response.result;

 	if (response.data_len > msg->insize) {
 		dev_err(ec->dev,
 			"packet too long (%d bytes, expected %d)",
 			response.data_len, msg->insize);
 		ret = -EMSGSIZE;
 		goto done;
 	}

 	/* Read response and process checksum */
 	sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET +
 				      sizeof(response), response.data_len,
 				      msg->data);

 	if (sum) {
 		dev_err(ec->dev,
 			"bad packet checksum %02x\n",
 			response.checksum);
 		ret = -EBADMSG;
 		goto done;
 	}

 	/* Return actual amount of data received */
 	ret = response.data_len;
 done:
 	return ret;
 }

 static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
 				struct cros_ec_command *msg)
 {
 	struct ec_lpc_host_args args;
 	u8 sum;
 	int ret = 0;

 	if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE ||
 	    msg->insize > EC_PROTO2_MAX_PARAM_SIZE) {
 		dev_err(ec->dev,
 			"invalid buffer sizes (out %d, in %d)\n",
 			msg->outsize, msg->insize);
 		return -EINVAL;
 	}

 	/* Now actually send the command to the EC and get the result */
 	args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
 	args.command_version = msg->version;
 	args.data_size = msg->outsize;

 	/* Initialize checksum */
 	sum = msg->command + args.flags + args.command_version + args.data_size;

 	/* Copy data and update checksum */
 	sum += cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PARAM, msg->outsize,
 				       msg->data);

 	/* Finalize checksum and write args */
 	args.checksum = sum;
 	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
 				(u8 *)&args);

 	/* Here we go */
 	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");
 		ret = -EIO;
 		goto done;
 	}

 	/* Check result */
 	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 */
 	cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
 			       (u8 *)&args);

 	if (args.data_size > msg->insize) {
 		dev_err(ec->dev,
 			"packet too long (%d bytes, expected %d)",
 			args.data_size, msg->insize);
 		ret = -ENOSPC;
 		goto done;
 	}

 	/* Start calculating response checksum */
 	sum = msg->command + args.flags + args.command_version + args.data_size;

 	/* Read response and update checksum */
 	sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PARAM, args.data_size,
 				      msg->data);

 	/* Verify checksum */
 	if (args.checksum != sum) {
 		dev_err(ec->dev,
 			"bad packet checksum, expected %02x, got %02x\n",
 			args.checksum, sum);
 		ret = -EBADMSG;
 		goto done;
 	}

 	/* Return actual amount of data received */
 	ret = args.data_size;
 done:
 	return ret;
 }

 /* Returns num bytes read, or negative on error. Doesn't need locking. */
 static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
 			       unsigned int bytes, void *dest)
 {
 	int i = offset;
 	char *s = dest;
 	int cnt = 0;

 	if (offset >= EC_MEMMAP_SIZE - bytes)
 		return -EINVAL;

 	/* fixed length */
 	if (bytes) {
 		cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + offset, bytes, s);
 		return bytes;
 	}

 	/* string */
 	for (; i < EC_MEMMAP_SIZE; i++, s++) {
 		cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + i, 1, s);
 		cnt++;
 		if (!*s)
 			break;
 	}

 	return cnt;
 }

 static void cros_ec_lpc_acpi_notify(acpi_handle device, u32 value, void *data)
 {
 	struct cros_ec_device *ec_dev = data;

 	if (ec_dev->mkbp_event_supported &&
 	    cros_ec_get_next_event(ec_dev, NULL) > 0)
 		blocking_notifier_call_chain(&ec_dev->event_notifier, 0,
 					     ec_dev);

 	if (value == ACPI_NOTIFY_DEVICE_WAKE)
 		pm_system_wakeup();
 }

 static int cros_ec_lpc_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct acpi_device *adev;
 	acpi_status status;
 	struct cros_ec_device *ec_dev;
 	u8 buf[2];
 	int irq, ret;

 	if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
 				 dev_name(dev))) {
 		dev_err(dev, "couldn't reserve memmap region\n");
 		return -EBUSY;
 	}

 	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;
 	}

 	if (!devm_request_region(dev, EC_HOST_CMD_REGION0,
 				 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
 		dev_err(dev, "couldn't reserve region0\n");
 		return -EBUSY;
 	}
 	if (!devm_request_region(dev, EC_HOST_CMD_REGION1,
 				 EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
 		dev_err(dev, "couldn't reserve region1\n");
 		return -EBUSY;
 	}

 	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
 	if (!ec_dev)
 		return -ENOMEM;

 	platform_set_drvdata(pdev, ec_dev);
 	ec_dev->dev = dev;
 	ec_dev->phys_name = dev_name(dev);
 	ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
 	ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
 	ec_dev->cmd_readmem = cros_ec_lpc_readmem;
 	ec_dev->din_size = sizeof(struct ec_host_response) +
 			   sizeof(struct ec_response_get_protocol_info);
 	ec_dev->dout_size = sizeof(struct ec_host_request);

 	/*
 	 * Some boards do not have an IRQ allotted for cros_ec_lpc,
 	 * which makes ENXIO an expected (and safe) scenario.
 	 */
 	irq = platform_get_irq(pdev, 0);
 	if (irq > 0)
 		ec_dev->irq = irq;
 	else if (irq != -ENXIO) {
 		dev_err(dev, "couldn't retrieve IRQ number (%d)\n", irq);
 		return irq;
 	}

 	ret = cros_ec_register(ec_dev);
 	if (ret) {
 		dev_err(dev, "couldn't register ec_dev (%d)\n", ret);
 		return ret;
 	}

 	/*
 	 * Connect a notify handler to process MKBP messages if we have a
 	 * companion ACPI device.
 	 */
 	adev = ACPI_COMPANION(dev);
 	if (adev) {
 		status = acpi_install_notify_handler(adev->handle,
 						     ACPI_ALL_NOTIFY,
 						     cros_ec_lpc_acpi_notify,
 						     ec_dev);
 		if (ACPI_FAILURE(status))
 			dev_warn(dev, "Failed to register notifier %08x\n",
 				 status);
 	}

 	return 0;
 }

 static int cros_ec_lpc_remove(struct platform_device *pdev)
 {
 	struct acpi_device *adev;

 	adev = ACPI_COMPANION(&pdev->dev);
 	if (adev)
 		acpi_remove_notify_handler(adev->handle, ACPI_ALL_NOTIFY,
 					   cros_ec_lpc_acpi_notify);

 	return 0;
 }

 static const struct acpi_device_id cros_ec_lpc_acpi_device_ids[] = {
 	{ ACPI_DRV_NAME, 0 },
 	{ }
 };
 MODULE_DEVICE_TABLE(acpi, cros_ec_lpc_acpi_device_ids);

 static const struct dmi_system_id cros_ec_lpc_dmi_table[] __initconst = {
 	{
 		/*
 		 * Today all Chromebooks/boxes ship with Google_* as version and
 		 * coreboot as bios vendor. No other systems with this
 		 * combination are known to date.
 		 */
 		.matches = {
 			DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
 			DMI_MATCH(DMI_BIOS_VERSION, "Google_"),
 		},
 	},
 	{
 		/*
 		 * If the box is running custom coreboot firmware then the
 		 * DMI BIOS version string will not be matched by "Google_",
 		 * but the system vendor string will still be matched by
 		 * "GOOGLE".
 		 */
 		.matches = {
 			DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
 			DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
 		},
 	},
 	{
 		/* x86-link, the Chromebook Pixel. */
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
 			DMI_MATCH(DMI_PRODUCT_NAME, "Link"),
 		},
 	},
 	{
 		/* x86-samus, the Chromebook Pixel 2. */
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
 			DMI_MATCH(DMI_PRODUCT_NAME, "Samus"),
 		},
 	},
 	{
 		/* x86-peppy, the Acer C720 Chromebook. */
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
 			DMI_MATCH(DMI_PRODUCT_NAME, "Peppy"),
 		},
 	},
 	{
 		/* x86-glimmer, the Lenovo Thinkpad Yoga 11e. */
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
 			DMI_MATCH(DMI_PRODUCT_NAME, "Glimmer"),
 		},
 	},
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(dmi, cros_ec_lpc_dmi_table);

 #ifdef CONFIG_PM_SLEEP
 static int cros_ec_lpc_suspend(struct device *dev)
 {
 	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);

 	return cros_ec_suspend(ec_dev);
 }

 static int cros_ec_lpc_resume(struct device *dev)
 {
 	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);

 	return cros_ec_resume(ec_dev);
 }
 #endif

 const struct dev_pm_ops cros_ec_lpc_pm_ops = {
 	SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_lpc_suspend, cros_ec_lpc_resume)
 };

 static struct platform_driver cros_ec_lpc_driver = {
 	.driver = {
 		.name = DRV_NAME,
 		.acpi_match_table = cros_ec_lpc_acpi_device_ids,
 		.pm = &cros_ec_lpc_pm_ops,
 	},
 	.probe = cros_ec_lpc_probe,
 	.remove = cros_ec_lpc_remove,
 };

 static struct platform_device cros_ec_lpc_device = {
 	.name = DRV_NAME
 };

 static acpi_status cros_ec_lpc_parse_device(acpi_handle handle, u32 level,
 					    void *context, void **retval)
 {
 	*(bool *)context = true;
 	return AE_CTRL_TERMINATE;
 }

 static int __init cros_ec_lpc_init(void)
 {
 	int ret;
 	acpi_status status;

 	status = acpi_get_devices(ACPI_DRV_NAME, cros_ec_lpc_parse_device,
 				  &cros_ec_lpc_acpi_device_found, NULL);
 	if (ACPI_FAILURE(status))
 		pr_warn(DRV_NAME ": Looking for %s failed\n", ACPI_DRV_NAME);

 	if (!cros_ec_lpc_acpi_device_found &&
 	    !dmi_check_system(cros_ec_lpc_dmi_table)) {
 		pr_err(DRV_NAME ": unsupported system.\n");
 		return -ENODEV;
 	}

 	cros_ec_lpc_reg_init();

 	/* Register the driver */
 	ret = platform_driver_register(&cros_ec_lpc_driver);
 	if (ret) {
 		pr_err(DRV_NAME ": can't register driver: %d\n", ret);
 		cros_ec_lpc_reg_destroy();
 		return ret;
 	}

 	if (!cros_ec_lpc_acpi_device_found) {
 		/* Register the device, and it'll get hooked up automatically */
 		ret = platform_device_register(&cros_ec_lpc_device);
 		if (ret) {
 			pr_err(DRV_NAME ": can't register device: %d\n", ret);
 			platform_driver_unregister(&cros_ec_lpc_driver);
 			cros_ec_lpc_reg_destroy();
 		}
 	}

 	return ret;
 }

 static void __exit cros_ec_lpc_exit(void)
 {
 	if (!cros_ec_lpc_acpi_device_found)
 		platform_device_unregister(&cros_ec_lpc_device);
 	platform_driver_unregister(&cros_ec_lpc_driver);
 	cros_ec_lpc_reg_destroy();
 }

 module_init(cros_ec_lpc_init);
 module_exit(cros_ec_lpc_exit);

 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("ChromeOS EC LPC driver");
	// SPDX-License-Identifier: GPL-2.0
	// LPC interface for ChromeOS Embedded Controller
	//
	// Copyright (C) 2012-2015 Google, Inc
	//
	// This driver uses the ChromeOS 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/acpi.h>
	#include <linux/dmi.h>
	#include <linux/delay.h>
	#include <linux/io.h>
	#include <linux/interrupt.h>
	#include <linux/mfd/cros_ec.h>
	#include <linux/mfd/cros_ec_commands.h>
	#include <linux/module.h>
	#include <linux/platform_device.h>
	#include <linux/printk.h>
	#include <linux/suspend.h>

	#include "cros_ec_lpc_reg.h"

	#define DRV_NAME "cros_ec_lpcs"
	#define ACPI_DRV_NAME "GOOG0004"

	/* True if ACPI device is present */
	static bool cros_ec_lpc_acpi_device_found;

	static int ec_response_timed_out(void)
	{
	unsigned long one_second = jiffies + HZ;
	u8 data;

	usleep_range(200, 300);
	do {
	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));

	return 1;
	}

	static int cros_ec_pkt_xfer_lpc(struct cros_ec_device *ec,
	struct cros_ec_command *msg)
	{
	struct ec_host_response response;
	u8 sum;
	int ret = 0;
	u8 *dout;

	ret = cros_ec_prepare_tx(ec, msg);

	/* Write buffer */
	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PACKET, ret, ec->dout);

	/* Here we go */
	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");
	ret = -EIO;
	goto done;
	}

	/* Check result */
	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;
	sum = cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET, sizeof(response),
	dout);

	msg->result = response.result;

	if (response.data_len > msg->insize) {
	dev_err(ec->dev,
	"packet too long (%d bytes, expected %d)",
	response.data_len, msg->insize);
	ret = -EMSGSIZE;
	goto done;
	}

	/* Read response and process checksum */
	sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PACKET +
	sizeof(response), response.data_len,
	msg->data);

	if (sum) {
	dev_err(ec->dev,
	"bad packet checksum %02x\n",
	response.checksum);
	ret = -EBADMSG;
	goto done;
	}

	/* Return actual amount of data received */
	ret = response.data_len;
	done:
	return ret;
	}

	static int cros_ec_cmd_xfer_lpc(struct cros_ec_device *ec,
	struct cros_ec_command *msg)
	{
	struct ec_lpc_host_args args;
	u8 sum;
	int ret = 0;

	if (msg->outsize > EC_PROTO2_MAX_PARAM_SIZE \|\|
	msg->insize > EC_PROTO2_MAX_PARAM_SIZE) {
	dev_err(ec->dev,
	"invalid buffer sizes (out %d, in %d)\n",
	msg->outsize, msg->insize);
	return -EINVAL;
	}

	/* Now actually send the command to the EC and get the result */
	args.flags = EC_HOST_ARGS_FLAG_FROM_HOST;
	args.command_version = msg->version;
	args.data_size = msg->outsize;

	/* Initialize checksum */
	sum = msg->command + args.flags + args.command_version + args.data_size;

	/* Copy data and update checksum */
	sum += cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_PARAM, msg->outsize,
	msg->data);

	/* Finalize checksum and write args */
	args.checksum = sum;
	cros_ec_lpc_write_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
	(u8 *)&args);

	/* Here we go */
	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");
	ret = -EIO;
	goto done;
	}

	/* Check result */
	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 */
	cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_ARGS, sizeof(args),
	(u8 *)&args);

	if (args.data_size > msg->insize) {
	dev_err(ec->dev,
	"packet too long (%d bytes, expected %d)",
	args.data_size, msg->insize);
	ret = -ENOSPC;
	goto done;
	}

	/* Start calculating response checksum */
	sum = msg->command + args.flags + args.command_version + args.data_size;

	/* Read response and update checksum */
	sum += cros_ec_lpc_read_bytes(EC_LPC_ADDR_HOST_PARAM, args.data_size,
	msg->data);

	/* Verify checksum */
	if (args.checksum != sum) {
	dev_err(ec->dev,
	"bad packet checksum, expected %02x, got %02x\n",
	args.checksum, sum);
	ret = -EBADMSG;
	goto done;
	}

	/* Return actual amount of data received */
	ret = args.data_size;
	done:
	return ret;
	}

	/* Returns num bytes read, or negative on error. Doesn't need locking. */
	static int cros_ec_lpc_readmem(struct cros_ec_device *ec, unsigned int offset,
	unsigned int bytes, void *dest)
	{
	int i = offset;
	char *s = dest;
	int cnt = 0;

	if (offset >= EC_MEMMAP_SIZE - bytes)
	return -EINVAL;

	/* fixed length */
	if (bytes) {
	cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + offset, bytes, s);
	return bytes;
	}

	/* string */
	for (; i < EC_MEMMAP_SIZE; i++, s++) {
	cros_ec_lpc_read_bytes(EC_LPC_ADDR_MEMMAP + i, 1, s);
	cnt++;
	if (!*s)
	break;
	}

	return cnt;
	}

	static void cros_ec_lpc_acpi_notify(acpi_handle device, u32 value, void *data)
	{
	struct cros_ec_device *ec_dev = data;

	if (ec_dev->mkbp_event_supported &&
	cros_ec_get_next_event(ec_dev, NULL) > 0)
	blocking_notifier_call_chain(&ec_dev->event_notifier, 0,
	ec_dev);

	if (value == ACPI_NOTIFY_DEVICE_WAKE)
	pm_system_wakeup();
	}

	static int cros_ec_lpc_probe(struct platform_device *pdev)
	{
	struct device *dev = &pdev->dev;
	struct acpi_device *adev;
	acpi_status status;
	struct cros_ec_device *ec_dev;
	u8 buf[2];
	int irq, ret;

	if (!devm_request_region(dev, EC_LPC_ADDR_MEMMAP, EC_MEMMAP_SIZE,
	dev_name(dev))) {
	dev_err(dev, "couldn't reserve memmap region\n");
	return -EBUSY;
	}

	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;
	}

	if (!devm_request_region(dev, EC_HOST_CMD_REGION0,
	EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
	dev_err(dev, "couldn't reserve region0\n");
	return -EBUSY;
	}
	if (!devm_request_region(dev, EC_HOST_CMD_REGION1,
	EC_HOST_CMD_REGION_SIZE, dev_name(dev))) {
	dev_err(dev, "couldn't reserve region1\n");
	return -EBUSY;
	}

	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
	if (!ec_dev)
	return -ENOMEM;

	platform_set_drvdata(pdev, ec_dev);
	ec_dev->dev = dev;
	ec_dev->phys_name = dev_name(dev);
	ec_dev->cmd_xfer = cros_ec_cmd_xfer_lpc;
	ec_dev->pkt_xfer = cros_ec_pkt_xfer_lpc;
	ec_dev->cmd_readmem = cros_ec_lpc_readmem;
	ec_dev->din_size = sizeof(struct ec_host_response) +
	sizeof(struct ec_response_get_protocol_info);
	ec_dev->dout_size = sizeof(struct ec_host_request);

	/*
	* Some boards do not have an IRQ allotted for cros_ec_lpc,
	* which makes ENXIO an expected (and safe) scenario.
	*/
	irq = platform_get_irq(pdev, 0);
	if (irq > 0)
	ec_dev->irq = irq;
	else if (irq != -ENXIO) {
	dev_err(dev, "couldn't retrieve IRQ number (%d)\n", irq);
	return irq;
	}

	ret = cros_ec_register(ec_dev);
	if (ret) {
	dev_err(dev, "couldn't register ec_dev (%d)\n", ret);
	return ret;
	}

	/*
	* Connect a notify handler to process MKBP messages if we have a
	* companion ACPI device.
	*/
	adev = ACPI_COMPANION(dev);
	if (adev) {
	status = acpi_install_notify_handler(adev->handle,
	ACPI_ALL_NOTIFY,
	cros_ec_lpc_acpi_notify,
	ec_dev);
	if (ACPI_FAILURE(status))
	dev_warn(dev, "Failed to register notifier %08x\n",
	status);
	}

	return 0;
	}

	static int cros_ec_lpc_remove(struct platform_device *pdev)
	{
	struct acpi_device *adev;

	adev = ACPI_COMPANION(&pdev->dev);
	if (adev)
	acpi_remove_notify_handler(adev->handle, ACPI_ALL_NOTIFY,
	cros_ec_lpc_acpi_notify);

	return 0;
	}

	static const struct acpi_device_id cros_ec_lpc_acpi_device_ids[] = {
	{ ACPI_DRV_NAME, 0 },
	{ }
	};
	MODULE_DEVICE_TABLE(acpi, cros_ec_lpc_acpi_device_ids);

	static const struct dmi_system_id cros_ec_lpc_dmi_table[] __initconst = {
	{
	/*
	* Today all Chromebooks/boxes ship with Google_* as version and
	* coreboot as bios vendor. No other systems with this
	* combination are known to date.
	*/
	.matches = {
	DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
	DMI_MATCH(DMI_BIOS_VERSION, "Google_"),
	},
	},
	{
	/*
	* If the box is running custom coreboot firmware then the
	* DMI BIOS version string will not be matched by "Google_",
	* but the system vendor string will still be matched by
	* "GOOGLE".
	*/
	.matches = {
	DMI_MATCH(DMI_BIOS_VENDOR, "coreboot"),
	DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
	},
	},
	{
	/* x86-link, the Chromebook Pixel. */
	.matches = {
	DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
	DMI_MATCH(DMI_PRODUCT_NAME, "Link"),
	},
	},
	{
	/* x86-samus, the Chromebook Pixel 2. */
	.matches = {
	DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
	DMI_MATCH(DMI_PRODUCT_NAME, "Samus"),
	},
	},
	{
	/* x86-peppy, the Acer C720 Chromebook. */
	.matches = {
	DMI_MATCH(DMI_SYS_VENDOR, "Acer"),
	DMI_MATCH(DMI_PRODUCT_NAME, "Peppy"),
	},
	},
	{
	/* x86-glimmer, the Lenovo Thinkpad Yoga 11e. */
	.matches = {
	DMI_MATCH(DMI_SYS_VENDOR, "GOOGLE"),
	DMI_MATCH(DMI_PRODUCT_NAME, "Glimmer"),
	},
	},
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(dmi, cros_ec_lpc_dmi_table);

	#ifdef CONFIG_PM_SLEEP
	static int cros_ec_lpc_suspend(struct device *dev)
	{
	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);

	return cros_ec_suspend(ec_dev);
	}

	static int cros_ec_lpc_resume(struct device *dev)
	{
	struct cros_ec_device *ec_dev = dev_get_drvdata(dev);

	return cros_ec_resume(ec_dev);
	}
	#endif

	const struct dev_pm_ops cros_ec_lpc_pm_ops = {
	SET_LATE_SYSTEM_SLEEP_PM_OPS(cros_ec_lpc_suspend, cros_ec_lpc_resume)
	};

	static struct platform_driver cros_ec_lpc_driver = {
	.driver = {
	.name = DRV_NAME,
	.acpi_match_table = cros_ec_lpc_acpi_device_ids,
	.pm = &cros_ec_lpc_pm_ops,
	},
	.probe = cros_ec_lpc_probe,
	.remove = cros_ec_lpc_remove,
	};

	static struct platform_device cros_ec_lpc_device = {
	.name = DRV_NAME
	};

	static acpi_status cros_ec_lpc_parse_device(acpi_handle handle, u32 level,
	void context, void *retval)
	{
	(bool )context = true;
	return AE_CTRL_TERMINATE;
	}

	static int __init cros_ec_lpc_init(void)
	{
	int ret;
	acpi_status status;

	status = acpi_get_devices(ACPI_DRV_NAME, cros_ec_lpc_parse_device,
	&cros_ec_lpc_acpi_device_found, NULL);
	if (ACPI_FAILURE(status))
	pr_warn(DRV_NAME ": Looking for %s failed\n", ACPI_DRV_NAME);

	if (!cros_ec_lpc_acpi_device_found &&
	!dmi_check_system(cros_ec_lpc_dmi_table)) {
	pr_err(DRV_NAME ": unsupported system.\n");
	return -ENODEV;
	}

	cros_ec_lpc_reg_init();

	/* Register the driver */
	ret = platform_driver_register(&cros_ec_lpc_driver);
	if (ret) {
	pr_err(DRV_NAME ": can't register driver: %d\n", ret);
	cros_ec_lpc_reg_destroy();
	return ret;
	}

	if (!cros_ec_lpc_acpi_device_found) {
	/* Register the device, and it'll get hooked up automatically */
	ret = platform_device_register(&cros_ec_lpc_device);
	if (ret) {
	pr_err(DRV_NAME ": can't register device: %d\n", ret);
	platform_driver_unregister(&cros_ec_lpc_driver);
	cros_ec_lpc_reg_destroy();
	}
	}

	return ret;
	}

	static void __exit cros_ec_lpc_exit(void)
	{
	if (!cros_ec_lpc_acpi_device_found)
	platform_device_unregister(&cros_ec_lpc_device);
	platform_driver_unregister(&cros_ec_lpc_driver);
	cros_ec_lpc_reg_destroy();
	}

	module_init(cros_ec_lpc_init);
	module_exit(cros_ec_lpc_exit);

	MODULE_LICENSE("GPL");
	MODULE_DESCRIPTION("ChromeOS EC LPC driver");