[v10,13/15] platform/x86: wmi: create userspace interface for drivers

Message ID	175838453318108ae69be344c4d3a2b75c2edc69.1508434514.git.mario.limonciello@dell.com (mailing list archive)
State	Superseded, archived
Delegated to:	Darren Hart
Headers	show Return-Path: <platform-driver-x86-owner@kernel.org> From: Mario Limonciello <mario.limonciello@dell.com> To: dvhart@infradead.org, Andy Shevchenko <andy.shevchenko@gmail.com> Cc: LKML <linux-kernel@vger.kernel.org>, platform-driver-x86@vger.kernel.org, Andy Lutomirski <luto@kernel.org>, quasisec@google.com, pali.rohar@gmail.com, rjw@rjwysocki.net, mjg59@google.com, hch@lst.de, Greg KH <greg@kroah.com>, Alan Cox <gnomes@lxorguk.ukuu.org.uk>, Mario Limonciello <mario.limonciello@dell.com> Subject: [PATCH v10 13/15] platform/x86: wmi: create userspace interface for drivers Date: Thu, 19 Oct 2017 12:50:16 -0500 Message-Id: <175838453318108ae69be344c4d3a2b75c2edc69.1508434514.git.mario.limonciello@dell.com> In-Reply-To: <cover.1508434513.git.mario.limonciello@dell.com> References: <cover.1508434513.git.mario.limonciello@dell.com> In-Reply-To: <cover.1508434513.git.mario.limonciello@dell.com> References: <cover.1508434513.git.mario.limonciello@dell.com> Sender: platform-driver-x86-owner@vger.kernel.org Precedence: bulk

diff --git a/MAINTAINERS b/MAINTAINERS index 8fd2f0d2ddf6..84afbf8ef7d5 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -384,6 +384,7 @@ ACPI WMI DRIVER L: platform-driver-x86@vger.kernel.org S: Orphan F: drivers/platform/x86/wmi.c +F: include/uapi/linux/wmi.h AD1889 ALSA SOUND DRIVER M: Thibaut Varene <T-Bone@parisc-linux.org> diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c index bcb41c1c7f52..41fa21be79c5 100644 --- a/drivers/platform/x86/wmi.c +++ b/drivers/platform/x86/wmi.c @@ -38,12 +38,15 @@ #include <linux/init.h> #include <linux/kernel.h> #include <linux/list.h> +#include <linux/miscdevice.h> #include <linux/module.h> #include <linux/platform_device.h> #include <linux/slab.h> #include <linux/types.h> +#include <linux/uaccess.h> #include <linux/uuid.h> #include <linux/wmi.h> +#include <uapi/linux/wmi.h> ACPI_MODULE_NAME("wmi"); MODULE_AUTHOR("Carlos Corbacho"); @@ -69,9 +72,12 @@ struct wmi_block { struct wmi_device dev; struct list_head list; struct guid_block gblock; + struct miscdevice char_dev; + struct mutex char_mutex; struct acpi_device *acpi_device; wmi_notify_handler handler; void *handler_data; + u64 req_buf_size; bool read_takes_no_args; }; @@ -188,6 +194,26 @@ static acpi_status wmi_method_enable(struct wmi_block *wblock, int enable) /* * Exported WMI functions */ + +/** + * set_required_buffer_size - Sets the buffer size needed for performing IOCTL + * @wdev: A wmi bus device from a driver + * @instance: Instance index + * + * Allocates memory needed for buffer, stores the buffer size in that memory + */ +int set_required_buffer_size(struct wmi_device *wdev, u8 instance, u64 length) +{ + struct wmi_block *wblock; + + wblock = container_of(wdev, struct wmi_block, dev); + if (!wblock) + return -ENODEV; + wblock->req_buf_size = length; + return 0; +} +EXPORT_SYMBOL_GPL(set_required_buffer_size); + /** * wmi_evaluate_method - Evaluate a WMI method * @guid_string: 36 char string of the form fa50ff2b-f2e8-45de-83fa-65417f2f49ba @@ -764,6 +790,127 @@ static int wmi_dev_match(struct device *dev, struct device_driver *driver) return 0; } +static int wmi_char_open(struct inode *inode, struct file *filp) +{ + const char *driver_name = filp->f_path.dentry->d_iname; + struct wmi_driver *wdriver = NULL; + struct wmi_block *wblock = NULL; + struct wmi_block *next = NULL; + + list_for_each_entry_safe(wblock, next, &wmi_block_list, list) { + wdriver = container_of(wblock->dev.dev.driver, + struct wmi_driver, driver); + if (!wdriver) + continue; + if (strcmp(driver_name, wdriver->driver.name) == 0) + break; + } + + if (!wdriver) + return -ENODEV; + + filp->private_data = wblock; + return nonseekable_open(inode, filp); +} + +static ssize_t wmi_char_read(struct file *filp, char __user *buffer, + size_t length, loff_t *offset) +{ + struct wmi_block *wblock = filp->private_data; + size_t count; + + if (*offset != 0) + return 0; + + count = sizeof(wblock->req_buf_size); + count = length < count ? length : count; + + if (copy_to_user(buffer, &wblock->req_buf_size, count)) + return -EFAULT; + + *offset = count; + return count; +} + +static long wmi_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) +{ + struct wmi_ioctl_buffer __user *input = + (struct wmi_ioctl_buffer __user *) arg; + struct wmi_block *wblock = filp->private_data; + struct wmi_ioctl_buffer *buf = NULL; + struct wmi_driver *wdriver = NULL; + int ret; + + if (_IOC_TYPE(cmd) != WMI_IOC) + return -ENOTTY; + + wdriver = container_of(wblock->dev.dev.driver, + struct wmi_driver, driver); + + if (!wdriver) + return -ENODEV; + + /* make sure we're not calling a higher instance than exists*/ + if (_IOC_NR(cmd) >= wblock->gblock.instance_count) + return -EINVAL; + + mutex_lock(&wblock->char_mutex); + buf = wblock->handler_data; + if (get_user(buf->length, &input->length)) { + dev_dbg(&wblock->dev.dev, "Read length from user failed\n"); + ret = -EFAULT; + goto out_ioctl; + } + /* if it's too small, abort */ + if (buf->length < wblock->req_buf_size) { + dev_err(&wblock->dev.dev, + "Buffer %lld too small, need at least %lld\n", + buf->length, wblock->req_buf_size); + ret = -EINVAL; + goto out_ioctl; + } + /* if it's too big, warn, driver will only use what is needed */ + if (buf->length > wblock->req_buf_size) + dev_warn(&wblock->dev.dev, + "Buffer %lld is bigger than required %lld\n", + buf->length, wblock->req_buf_size); + + if (copy_from_user(buf, input, wblock->req_buf_size)) { + dev_dbg(&wblock->dev.dev, "Copy %llu from user failed\n", + wblock->req_buf_size); + ret = -EFAULT; + goto out_ioctl; + } + + /* let the driver do any filtering and do the call */ + if (!try_module_get(wdriver->driver.owner)) + return -EBUSY; + ret = wdriver->filter_callback(&wblock->dev, cmd, buf); + module_put(wdriver->driver.owner); + if (ret) + goto out_ioctl; + + /* return the result (only up to our internal buffer size) */ + if (copy_to_user(input, buf, wblock->req_buf_size)) { + dev_dbg(&wblock->dev.dev, "Copy %llu to user failed\n", + wblock->req_buf_size); + ret = -EFAULT; + } + +out_ioctl: + mutex_unlock(&wblock->char_mutex); + return ret; +} + +static const struct file_operations wmi_fops = { + .owner = THIS_MODULE, + .read = wmi_char_read, + .open = wmi_char_open, + .unlocked_ioctl = wmi_ioctl, +#ifdef CONFIG_COMPAT + .compat_ioctl = wmi_ioctl, +#endif +}; static int wmi_dev_probe(struct device *dev) { @@ -771,16 +918,63 @@ static int wmi_dev_probe(struct device *dev) struct wmi_driver *wdriver = container_of(dev->driver, struct wmi_driver, driver); int ret = 0; + int count; + char *buf; if (ACPI_FAILURE(wmi_method_enable(wblock, 1))) dev_warn(dev, "failed to enable device -- probing anyway\n"); if (wdriver->probe) { ret = wdriver->probe(dev_to_wdev(dev)); - if (ret != 0 && ACPI_FAILURE(wmi_method_enable(wblock, 0))) - dev_warn(dev, "failed to disable device\n"); + if (ret != 0) + goto probe_failure; + } + + /* driver wants a character device made */ + if (wdriver->filter_callback) { + /* check that required buffer size declared by driver or MOF */ + if (!wblock->req_buf_size) { + dev_err(&wblock->dev.dev, + "Required buffer size not set\n"); + ret = -EINVAL; + goto probe_failure; + } + + count = get_order(wblock->req_buf_size); + wblock->handler_data = (void *)__get_free_pages(GFP_KERNEL, + count); + if (!wblock->handler_data) { + ret = -ENOMEM; + goto probe_failure; + } + + buf = kmalloc(strlen(wdriver->driver.name) + 4, GFP_KERNEL); + if (!buf) { + ret = -ENOMEM; + goto probe_string_failure; + } + sprintf(buf, "wmi/%s", wdriver->driver.name); + wblock->char_dev.minor = MISC_DYNAMIC_MINOR; + wblock->char_dev.name = buf; + wblock->char_dev.fops = &wmi_fops; + wblock->char_dev.mode = 0444; + ret = misc_register(&wblock->char_dev); + if (ret) { + dev_warn(dev, "failed to register char dev: %d", ret); + ret = -ENOMEM; + goto probe_misc_failure; + } } + return 0; + +probe_misc_failure: + kfree(buf); +probe_string_failure: + kfree(wblock->handler_data); +probe_failure: + if (ACPI_FAILURE(wmi_method_enable(wblock, 0))) + dev_warn(dev, "failed to disable device\n"); return ret; } @@ -791,6 +985,13 @@ static int wmi_dev_remove(struct device *dev) container_of(dev->driver, struct wmi_driver, driver); int ret = 0; + if (wdriver->filter_callback) { + misc_deregister(&wblock->char_dev); + kfree(wblock->char_dev.name); + free_pages((unsigned long)wblock->handler_data, + get_order(wblock->req_buf_size)); + } + if (wdriver->remove) ret = wdriver->remove(dev_to_wdev(dev)); @@ -847,6 +1048,7 @@ static int wmi_create_device(struct device *wmi_bus_dev, if (gblock->flags & ACPI_WMI_METHOD) { wblock->dev.dev.type = &wmi_type_method; + mutex_init(&wblock->char_mutex); goto out_init; } diff --git a/include/linux/wmi.h b/include/linux/wmi.h index ddee427e0721..0516cffea805 100644 --- a/include/linux/wmi.h +++ b/include/linux/wmi.h @@ -18,6 +18,7 @@ #include <linux/device.h> #include <linux/acpi.h> +#include <uapi/linux/wmi.h> struct wmi_device { struct device dev; @@ -36,6 +37,9 @@ extern acpi_status wmidev_evaluate_method(struct wmi_device *wdev, extern union acpi_object *wmidev_block_query(struct wmi_device *wdev, u8 instance); +extern int set_required_buffer_size(struct wmi_device *wdev, u8 instance, + u64 length); + struct wmi_device_id { const char *guid_string; }; @@ -47,6 +51,8 @@ struct wmi_driver { int (*probe)(struct wmi_device *wdev); int (*remove)(struct wmi_device *wdev); void (*notify)(struct wmi_device *device, union acpi_object *data); + long (*filter_callback)(struct wmi_device *wdev, unsigned int cmd, + struct wmi_ioctl_buffer *arg); }; extern int __must_check __wmi_driver_register(struct wmi_driver *driver, diff --git a/include/uapi/linux/wmi.h b/include/uapi/linux/wmi.h new file mode 100644 index 000000000000..7e52350ac9b3 --- /dev/null +++ b/include/uapi/linux/wmi.h @@ -0,0 +1,26 @@ +/* + * User API methods for ACPI-WMI mapping driver + * + * Copyright (C) 2017 Dell, Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ +#ifndef _UAPI_LINUX_WMI_H +#define _UAPI_LINUX_WMI_H + +#include <linux/types.h> + +/* WMI bus will filter all WMI vendor driver requests through this IOC */ +#define WMI_IOC 'W' + +/* All ioctl requests through WMI should declare their size followed by + * relevant data objects + */ +struct wmi_ioctl_buffer { + __u64 length; + __u8 data[]; +}; + +#endif

[v10,13/15] platform/x86: wmi: create userspace interface for drivers

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