[PATCH v4 4/7] platform/chrome: Add Chrome OS EC userspace device interface

Javier Martinez Canillas
2015-01-29T13:38:22Z

From: Bill Richardson <wfrichar@chromium.org>

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

Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-by: Simon Glass <sjg@google.com>
Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
---

Changes since v3: None.

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:aherrman@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:thomas@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) 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/>.
+ */
+
+#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 <wfrichar@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