3 files changed, 263 insertions, 0 deletions

diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
index eaeb04e07335..bd3524bd6b37 100644
--- a/drivers/platform/chrome/Kconfig
+++ b/drivers/platform/chrome/Kconfig
@@ -136,6 +136,17 @@ config CROS_KBD_LED_BACKLIGHT
 	  To compile this driver as a module, choose M here: the
 	  module will be called cros_kbd_led_backlight.
 
+config CROS_EC_CHARDEV
+	tristate "ChromeOS EC miscdevice"
+	depends on MFD_CROS_EC_CHARDEV
+	default MFD_CROS_EC_CHARDEV
+	help
+	  This driver adds file operations support to talk with the
+	  ChromeOS EC from userspace via a character device.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called cros_ec_chardev.
+
 config CROS_EC_LIGHTBAR
 	tristate "Chromebook Pixel's lightbar support"
 	depends on MFD_CROS_EC_CHARDEV
diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index 12ff8de5ac7a..477ec3d1d1c9 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -15,6 +15,7 @@ cros_ec_lpcs-objs			:= cros_ec_lpc.o cros_ec_lpc_mec.o
 obj-$(CONFIG_CROS_EC_LPC)		+= cros_ec_lpcs.o
 obj-$(CONFIG_CROS_EC_PROTO)		+= cros_ec_proto.o cros_ec_trace.o
 obj-$(CONFIG_CROS_KBD_LED_BACKLIGHT)	+= cros_kbd_led_backlight.o
+obj-$(CONFIG_CROS_EC_CHARDEV)		+= cros_ec_chardev.o
 obj-$(CONFIG_CROS_EC_LIGHTBAR)		+= cros_ec_lightbar.o
 obj-$(CONFIG_CROS_EC_VBC)		+= cros_ec_vbc.o
 obj-$(CONFIG_CROS_EC_DEBUGFS)		+= cros_ec_debugfs.o
diff --git a/drivers/platform/chrome/cros_ec_chardev.c b/drivers/platform/chrome/cros_ec_chardev.c
new file mode 100644
index 000000000000..174f940822c9
--- /dev/null
+++ b/drivers/platform/chrome/cros_ec_chardev.c
@@ -0,0 +1,251 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Miscellaneous character driver for ChromeOS Embedded Controller
+ *
+ * Copyright 2014 Google, Inc.
+ * Copyright 2019 Google LLC
+ *
+ * This file is a rework and part of the code is ported from
+ * drivers/mfd/cros_ec_dev.c that was originally written by
+ * Bill Richardson.
+ */
+
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/mfd/cros_ec.h>
+#include <linux/mfd/cros_ec_commands.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/platform_data/cros_ec_chardev.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/uaccess.h>
+
+#define DRV_NAME		"cros-ec-chardev"
+
+struct chardev_data {
+	struct cros_ec_dev *ec_dev;
+	struct miscdevice misc;
+};
+
+static int ec_get_version(struct cros_ec_dev *ec, char *str, int maxlen)
+{
+	static const char * const current_image_name[] = {
+		"unknown", "read-only", "read-write", "invalid",
+	};
+	struct ec_response_get_version *resp;
+	struct cros_ec_command *msg;
+	int ret;
+
+	msg = kzalloc(sizeof(*msg) + sizeof(*resp), GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	msg->command = EC_CMD_GET_VERSION + ec->cmd_offset;
+	msg->insize = sizeof(*resp);
+
+	ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
+	if (ret < 0) {
+		snprintf(str, maxlen,
+			 "Unknown EC version, returned error: %d\n",
+			 msg->result);
+		goto exit;
+	}
+
+	resp = (struct ec_response_get_version *)msg->data;
+	if (resp->current_image >= ARRAY_SIZE(current_image_name))
+		resp->current_image = 3; /* invalid */
+
+	snprintf(str, maxlen, "%s\n%s\n%s\n%s\n", CROS_EC_DEV_VERSION,
+		 resp->version_string_ro, resp->version_string_rw,
+		 current_image_name[resp->current_image]);
+
+	ret = 0;
+exit:
+	kfree(msg);
+	return ret;
+}
+
+/*
+ * Device file ops
+ */
+static int cros_ec_chardev_open(struct inode *inode, struct file *filp)
+{
+	struct miscdevice *mdev = filp->private_data;
+	struct cros_ec_dev *ec_dev = dev_get_drvdata(mdev->parent);
+
+	filp->private_data = ec_dev;
+	nonseekable_open(inode, filp);
+
+	return 0;
+}
+
+static ssize_t cros_ec_chardev_read(struct file *filp, char __user *buffer,
+				     size_t length, loff_t *offset)
+{
+	char msg[sizeof(struct ec_response_get_version) +
+		 sizeof(CROS_EC_DEV_VERSION)];
+	struct cros_ec_dev *ec = filp->private_data;
+	size_t count;
+	int ret;
+
+	if (*offset != 0)
+		return 0;
+
+	ret = ec_get_version(ec, msg, sizeof(msg));
+	if (ret)
+		return ret;
+
+	count = min(length, strlen(msg));
+
+	if (copy_to_user(buffer, msg, count))
+		return -EFAULT;
+
+	*offset = count;
+	return count;
+}
+
+/*
+ * Ioctls
+ */
+static long cros_ec_chardev_ioctl_xcmd(struct cros_ec_dev *ec, void __user *arg)
+{
+	struct cros_ec_command *s_cmd;
+	struct cros_ec_command u_cmd;
+	long ret;
+
+	if (copy_from_user(&u_cmd, arg, sizeof(u_cmd)))
+		return -EFAULT;
+
+	if (u_cmd.outsize > EC_MAX_MSG_BYTES ||
+	    u_cmd.insize > EC_MAX_MSG_BYTES)
+		return -EINVAL;
+
+	s_cmd = kmalloc(sizeof(*s_cmd) + max(u_cmd.outsize, u_cmd.insize),
+			GFP_KERNEL);
+	if (!s_cmd)
+		return -ENOMEM;
+
+	if (copy_from_user(s_cmd, arg, sizeof(*s_cmd) + u_cmd.outsize)) {
+		ret = -EFAULT;
+		goto exit;
+	}
+
+	if (u_cmd.outsize != s_cmd->outsize ||
+	    u_cmd.insize != s_cmd->insize) {
+		ret = -EINVAL;
+		goto exit;
+	}
+
+	s_cmd->command += ec->cmd_offset;
+	ret = cros_ec_cmd_xfer(ec->ec_dev, s_cmd);
+	/* Only copy data to userland if data was received. */
+	if (ret < 0)
+		goto exit;
+
+	if (copy_to_user(arg, s_cmd, sizeof(*s_cmd) + s_cmd->insize))
+		ret = -EFAULT;
+exit:
+	kfree(s_cmd);
+	return ret;
+}
+
+static long cros_ec_chardev_ioctl_readmem(struct cros_ec_dev *ec,
+					   void __user *arg)
+{
+	struct cros_ec_device *ec_dev = ec->ec_dev;
+	struct cros_ec_readmem s_mem = { };
+	long num;
+
+	/* Not every platform supports direct reads */
+	if (!ec_dev->cmd_readmem)
+		return -ENOTTY;
+
+	if (copy_from_user(&s_mem, arg, sizeof(s_mem)))
+		return -EFAULT;
+
+	num = ec_dev->cmd_readmem(ec_dev, s_mem.offset, s_mem.bytes,
+				  s_mem.buffer);
+	if (num <= 0)
+		return num;
+
+	if (copy_to_user((void __user *)arg, &s_mem, sizeof(s_mem)))
+		return -EFAULT;
+
+	return num;
+}
+
+static long cros_ec_chardev_ioctl(struct file *filp, unsigned int cmd,
+				   unsigned long arg)
+{
+	struct cros_ec_dev *ec = filp->private_data;
+
+	if (_IOC_TYPE(cmd) != CROS_EC_DEV_IOC)
+		return -ENOTTY;
+
+	switch (cmd) {
+	case CROS_EC_DEV_IOCXCMD:
+		return cros_ec_chardev_ioctl_xcmd(ec, (void __user *)arg);
+	case CROS_EC_DEV_IOCRDMEM:
+		return cros_ec_chardev_ioctl_readmem(ec, (void __user *)arg);
+	}
+
+	return -ENOTTY;
+}
+
+static const struct file_operations chardev_fops = {
+	.open		= cros_ec_chardev_open,
+	.read		= cros_ec_chardev_read,
+	.unlocked_ioctl	= cros_ec_chardev_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= cros_ec_chardev_ioctl,
+#endif
+};
+
+static int cros_ec_chardev_probe(struct platform_device *pdev)
+{
+	struct cros_ec_dev *ec_dev = dev_get_drvdata(pdev->dev.parent);
+	struct cros_ec_platform *ec_platform = dev_get_platdata(ec_dev->dev);
+	struct chardev_data *data;
+
+	/* Create a char device: we want to create it anew */
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->ec_dev = ec_dev;
+	data->misc.minor = MISC_DYNAMIC_MINOR;
+	data->misc.fops = &chardev_fops;
+	data->misc.name = ec_platform->ec_name;
+	data->misc.parent = pdev->dev.parent;
+
+	dev_set_drvdata(&pdev->dev, data);
+
+	return misc_register(&data->misc);
+}
+
+static int cros_ec_chardev_remove(struct platform_device *pdev)
+{
+	struct chardev_data *data = dev_get_drvdata(&pdev->dev);
+
+	misc_deregister(&data->misc);
+
+	return 0;
+}
+
+static struct platform_driver cros_ec_chardev_driver = {
+	.driver = {
+		.name = DRV_NAME,
+	},
+	.probe = cros_ec_chardev_probe,
+	.remove = cros_ec_chardev_remove,
+};
+
+module_platform_driver(cros_ec_chardev_driver);
+
+MODULE_ALIAS("platform:" DRV_NAME);
+MODULE_AUTHOR("Enric Balletbo i Serra <enric.balletbo@collabora.com>");
+MODULE_DESCRIPTION("ChromeOS EC Miscellaneous Character Driver");
+MODULE_LICENSE("GPL");