From: Bill Richardson <wfric...@chromium.org>

This patch adds a device interface to access the
Chrome OS Embedded Controller from user-space.

Signed-off-by: Bill Richardson <wfric...@chromium.org>
Reviewed-by: Simon Glass <s...@google.com>
Signed-off-by: Javier Martinez Canillas <javier.marti...@collabora.co.uk>
Reviewed-by: Gwendal Grignou <gwen...@chromium.org>
---

Changes since v2:
 - Rename the devname to "cros-ec-ctl". Suggested by Lee Jones.
 - Added Gwendal Grignou Reviewed-by tag.

Changes since v1: None, new patch.
---
 Documentation/ioctl/ioctl-number.txt  |   1 +
 drivers/platform/chrome/Kconfig       |  14 +-
 drivers/platform/chrome/Makefile      |   1 +
 drivers/platform/chrome/cros_ec_dev.c | 268 ++++++++++++++++++++++++++++++++++
 drivers/platform/chrome/cros_ec_dev.h |  47 ++++++
 5 files changed, 328 insertions(+), 3 deletions(-)
 create mode 100644 drivers/platform/chrome/cros_ec_dev.c
 create mode 100644 drivers/platform/chrome/cros_ec_dev.h

diff --git a/Documentation/ioctl/ioctl-number.txt 
b/Documentation/ioctl/ioctl-number.txt
index 8136e1fd30fd..51f4221657bf 100644
--- a/Documentation/ioctl/ioctl-number.txt
+++ b/Documentation/ioctl/ioctl-number.txt
@@ -321,6 +321,7 @@ Code  Seq#(hex)     Include File            Comments
 0xDB   00-0F   drivers/char/mwave/mwavepub.h
 0xDD   00-3F   ZFCP device driver      see drivers/s390/scsi/
                                        <mailto:aherr...@de.ibm.com>
+0xEC   00-01   drivers/platform/chrome/cros_ec_dev.h   ChromeOS EC driver
 0xF3   00-3F   drivers/usb/misc/sisusbvga/sisusb.h     sisfb (in development)
                                        <mailto:tho...@winischhofer.net>
 0xF4   00-1F   video/mbxfb.h           mbxfb
diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig
index 440ed776efd4..75dc514915ff 100644
--- a/drivers/platform/chrome/Kconfig
+++ b/drivers/platform/chrome/Kconfig
@@ -4,7 +4,7 @@
 
 menuconfig CHROME_PLATFORMS
        bool "Platform support for Chrome hardware"
-       depends on X86
+       depends on X86 || ARM
        ---help---
          Say Y here to get to see options for platform support for
          various Chromebooks and Chromeboxes. This option alone does
@@ -16,8 +16,7 @@ if CHROME_PLATFORMS
 
 config CHROMEOS_LAPTOP
        tristate "Chrome OS Laptop"
-       depends on I2C
-       depends on DMI
+       depends on I2C && DMI && X86
        ---help---
          This driver instantiates i2c and smbus devices such as
          light sensors and touchpads.
@@ -27,6 +26,7 @@ config CHROMEOS_LAPTOP
 
 config CHROMEOS_PSTORE
        tristate "Chrome OS pstore support"
+       depends on X86
        ---help---
          This module instantiates the persistent storage on x86 ChromeOS
          devices. It can be used to store away console logs and crash
@@ -38,5 +38,13 @@ config CHROMEOS_PSTORE
          If you have a supported Chromebook, choose Y or M here.
          The module will be called chromeos_pstore.
 
+config CROS_EC_CHARDEV
+        tristate "Chrome OS Embedded Controller userspace device interface"
+        depends on MFD_CROS_EC
+        ---help---
+          This driver adds support to talk with the ChromeOS EC from userspace.
+
+          If you have a supported Chromebook, choose Y or M here.
+          The module will be called cros_ec_dev.
 
 endif # CHROMEOS_PLATFORMS
diff --git a/drivers/platform/chrome/Makefile b/drivers/platform/chrome/Makefile
index 2b860ca7450f..10f1361a97b4 100644
--- a/drivers/platform/chrome/Makefile
+++ b/drivers/platform/chrome/Makefile
@@ -1,3 +1,4 @@
 
 obj-$(CONFIG_CHROMEOS_LAPTOP)  += chromeos_laptop.o
 obj-$(CONFIG_CHROMEOS_PSTORE)  += chromeos_pstore.o
+obj-$(CONFIG_CROS_EC_CHARDEV)  += cros_ec_dev.o
diff --git a/drivers/platform/chrome/cros_ec_dev.c 
b/drivers/platform/chrome/cros_ec_dev.c
new file mode 100644
index 000000000000..94c1442d5104
--- /dev/null
+++ b/drivers/platform/chrome/cros_ec_dev.c
@@ -0,0 +1,268 @@
+/*
+ * cros_ec_dev - expose the Chrome OS Embedded Controller to user-space
+ *
+ * Copyright (C) 2015 Google, Inc.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/uaccess.h>
+
+#include "cros_ec_dev.h"
+
+/* Device variables */
+#define CROS_MAX_DEV 128
+static struct class *cros_class;
+static int ec_major;
+
+/* Basic communication */
+static int ec_get_version(struct cros_ec_device *ec, char *str, int maxlen)
+{
+       struct ec_response_get_version *resp;
+       static const char * const current_image_name[] = {
+               "unknown", "read-only", "read-write", "invalid",
+       };
+       struct cros_ec_command msg = {
+               .version = 0,
+               .command = EC_CMD_GET_VERSION,
+               .outdata = { 0 },
+               .outsize = 0,
+               .indata = { 0 },
+               .insize = sizeof(*resp),
+       };
+       int ret;
+
+       ret = cros_ec_cmd_xfer(ec, &msg);
+       if (ret < 0)
+               return ret;
+
+       if (msg.result != EC_RES_SUCCESS) {
+               snprintf(str, maxlen,
+                        "%s\nUnknown EC version: EC returned %d\n",
+                        CROS_EC_DEV_VERSION, msg.result);
+               return 0;
+       }
+
+       resp = (struct ec_response_get_version *)msg.indata;
+       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]);
+
+       return 0;
+}
+
+/* Device file ops */
+static int ec_device_open(struct inode *inode, struct file *filp)
+{
+       filp->private_data = container_of(inode->i_cdev,
+                                         struct cros_ec_device, cdev);
+       return 0;
+}
+
+static int ec_device_release(struct inode *inode, struct file *filp)
+{
+       return 0;
+}
+
+static ssize_t ec_device_read(struct file *filp, char __user *buffer,
+                             size_t length, loff_t *offset)
+{
+       struct cros_ec_device *ec = filp->private_data;
+       char msg[sizeof(struct ec_response_get_version) +
+                sizeof(CROS_EC_DEV_VERSION)];
+       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 ec_device_ioctl_xcmd(struct cros_ec_device *ec, void __user *arg)
+{
+       long ret;
+       struct cros_ec_command s_cmd = { };
+
+       if (copy_from_user(&s_cmd, arg, sizeof(s_cmd)))
+               return -EFAULT;
+
+       ret = cros_ec_cmd_xfer(ec, &s_cmd);
+       /* Only copy data to userland if data was received. */
+       if (ret < 0)
+               return ret;
+
+       if (copy_to_user(arg, &s_cmd, sizeof(s_cmd)))
+               return -EFAULT;
+
+       return 0;
+}
+
+static long ec_device_ioctl_readmem(struct cros_ec_device *ec, void __user 
*arg)
+{
+       struct cros_ec_readmem s_mem = { };
+       long num;
+
+       /* Not every platform supports direct reads */
+       if (!ec->cmd_readmem)
+               return -ENOTTY;
+
+       if (copy_from_user(&s_mem, arg, sizeof(s_mem)))
+               return -EFAULT;
+
+       num = ec->cmd_readmem(ec, 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 0;
+}
+
+static long ec_device_ioctl(struct file *filp, unsigned int cmd,
+                           unsigned long arg)
+{
+       struct cros_ec_device *ec = filp->private_data;
+
+       if (_IOC_TYPE(cmd) != CROS_EC_DEV_IOC)
+               return -ENOTTY;
+
+       switch (cmd) {
+       case CROS_EC_DEV_IOCXCMD:
+               return ec_device_ioctl_xcmd(ec, (void __user *)arg);
+       case CROS_EC_DEV_IOCRDMEM:
+               return ec_device_ioctl_readmem(ec, (void __user *)arg);
+       }
+
+       return -ENOTTY;
+}
+
+/* Module initialization */
+static const struct file_operations fops = {
+       .open = ec_device_open,
+       .release = ec_device_release,
+       .read = ec_device_read,
+       .unlocked_ioctl = ec_device_ioctl,
+};
+
+static int ec_device_probe(struct platform_device *pdev)
+{
+       struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
+       int retval = -ENOTTY;
+       dev_t devno = MKDEV(ec_major, 0);
+
+       /* Instantiate it (and remember the EC) */
+       cdev_init(&ec->cdev, &fops);
+
+       retval = cdev_add(&ec->cdev, devno, 1);
+       if (retval) {
+               dev_err(&pdev->dev, ": failed to add character device\n");
+               return retval;
+       }
+
+       ec->vdev = device_create(cros_class, NULL, devno, ec,
+                                CROS_EC_DEV_NAME);
+       if (IS_ERR(ec->vdev)) {
+               retval = PTR_ERR(ec->vdev);
+               dev_err(&pdev->dev, ": failed to create device\n");
+               cdev_del(&ec->cdev);
+               return retval;
+       }
+
+       return 0;
+}
+
+static int ec_device_remove(struct platform_device *pdev)
+{
+       struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
+
+       device_destroy(cros_class, MKDEV(ec_major, 0));
+       cdev_del(&ec->cdev);
+       return 0;
+}
+
+static struct platform_driver cros_ec_dev_driver = {
+       .driver = {
+               .name = "cros-ec-ctl",
+       },
+       .probe = ec_device_probe,
+       .remove = ec_device_remove,
+};
+
+static int __init cros_ec_dev_init(void)
+{
+       int ret;
+       dev_t dev = 0;
+
+       cros_class = class_create(THIS_MODULE, "chromeos");
+       if (IS_ERR(cros_class)) {
+               pr_err(CROS_EC_DEV_NAME ": failed to register device class\n");
+               return PTR_ERR(cros_class);
+       }
+
+       /* Get a range of minor numbers (starting with 0) to work with */
+       ret = alloc_chrdev_region(&dev, 0, CROS_MAX_DEV, CROS_EC_DEV_NAME);
+       if (ret < 0) {
+               pr_err(CROS_EC_DEV_NAME ": alloc_chrdev_region() failed\n");
+               goto failed_chrdevreg;
+       }
+       ec_major = MAJOR(dev);
+
+       /* Register the driver */
+       ret = platform_driver_register(&cros_ec_dev_driver);
+       if (ret < 0) {
+               pr_warn(CROS_EC_DEV_NAME ": can't register driver: %d\n", ret);
+               goto failed_devreg;
+       }
+       return 0;
+
+failed_devreg:
+       unregister_chrdev_region(MKDEV(ec_major, 0), CROS_MAX_DEV);
+failed_chrdevreg:
+       class_destroy(cros_class);
+       return ret;
+}
+
+static void __exit cros_ec_dev_exit(void)
+{
+       platform_driver_unregister(&cros_ec_dev_driver);
+       unregister_chrdev(ec_major, CROS_EC_DEV_NAME);
+       class_destroy(cros_class);
+}
+
+module_init(cros_ec_dev_init);
+module_exit(cros_ec_dev_exit);
+
+MODULE_AUTHOR("Bill Richardson <wfric...@chromium.org>");
+MODULE_DESCRIPTION("Userspace interface to the Chrome OS Embedded Controller");
+MODULE_VERSION("1.0");
+MODULE_LICENSE("GPL");
diff --git a/drivers/platform/chrome/cros_ec_dev.h 
b/drivers/platform/chrome/cros_ec_dev.h
new file mode 100644
index 000000000000..15c54c4c5531
--- /dev/null
+++ b/drivers/platform/chrome/cros_ec_dev.h
@@ -0,0 +1,47 @@
+/*
+ * cros_ec_dev - expose the Chrome OS Embedded Controller to userspace
+ *
+ * Copyright (C) 2014 Google, Inc.
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _CROS_EC_DEV_H_
+#define _CROS_EC_DEV_H_
+
+#include <linux/ioctl.h>
+#include <linux/types.h>
+#include <linux/mfd/cros_ec.h>
+
+#define CROS_EC_DEV_NAME "cros_ec"
+#define CROS_EC_DEV_VERSION "1.0.0"
+
+/*
+ * @offset: within EC_LPC_ADDR_MEMMAP region
+ * @bytes: number of bytes to read. zero means "read a string" (including '\0')
+ *         (at most only EC_MEMMAP_SIZE bytes can be read)
+ * @buffer: where to store the result
+ * ioctl returns the number of bytes read, negative on error
+ */
+struct cros_ec_readmem {
+       uint32_t offset;
+       uint32_t bytes;
+       uint8_t buffer[EC_MEMMAP_SIZE];
+};
+
+#define CROS_EC_DEV_IOC       0xEC
+#define CROS_EC_DEV_IOCXCMD   _IOWR(CROS_EC_DEV_IOC, 0, struct cros_ec_command)
+#define CROS_EC_DEV_IOCRDMEM  _IOWR(CROS_EC_DEV_IOC, 1, struct cros_ec_readmem)
+
+#endif /* _CROS_EC_DEV_H_ */
-- 
2.1.3

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