1/*
  2 *  WMI methods for use with dell-smbios
  3 *
  4 *  Copyright (c) 2017 Dell Inc.
  5 *
  6 *  This program is free software; you can redistribute it and/or modify
  7 *  it under the terms of the GNU General Public License version 2 as
  8 *  published by the Free Software Foundation.
  9 */
 10#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 11
 12#include <linux/dmi.h>
 13#include <linux/list.h>
 14#include <linux/module.h>
 15#include <linux/mutex.h>
 16#include <linux/uaccess.h>
 17#include <linux/wmi.h>
 18#include "dell-smbios.h"
 19#include "dell-wmi-descriptor.h"
 20
 21static DEFINE_MUTEX(call_mutex);
 22static DEFINE_MUTEX(list_mutex);
 23static int wmi_supported;
 24
 25struct misc_bios_flags_structure {
 26	struct dmi_header header;
 27	u16 flags0;
 28} __packed;
 29#define FLAG_HAS_ACPI_WMI 0x02
 30
 31#define DELL_WMI_SMBIOS_GUID "A80593CE-A997-11DA-B012-B622A1EF5492"
 32
 33struct wmi_smbios_priv {
 34	struct dell_wmi_smbios_buffer *buf;
 35	struct list_head list;
 36	struct wmi_device *wdev;
 37	struct device *child;
 38	u32 req_buf_size;
 39};
 40static LIST_HEAD(wmi_list);
 41
 42static inline struct wmi_smbios_priv *get_first_smbios_priv(void)
 43{
 44	return list_first_entry_or_null(&wmi_list,
 45					struct wmi_smbios_priv,
 46					list);
 47}
 48
 49static int run_smbios_call(struct wmi_device *wdev)
 50{
 51	struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
 52	struct wmi_smbios_priv *priv;
 53	struct acpi_buffer input;
 54	union acpi_object *obj;
 55	acpi_status status;
 56
 57	priv = dev_get_drvdata(&wdev->dev);
 58	input.length = priv->req_buf_size - sizeof(u64);
 59	input.pointer = &priv->buf->std;
 60
 61	dev_dbg(&wdev->dev, "evaluating: %u/%u [%x,%x,%x,%x]\n",
 62		priv->buf->std.cmd_class, priv->buf->std.cmd_select,
 63		priv->buf->std.input[0], priv->buf->std.input[1],
 64		priv->buf->std.input[2], priv->buf->std.input[3]);
 65
 66	status = wmidev_evaluate_method(wdev, 0, 1, &input, &output);
 67	if (ACPI_FAILURE(status))
 68		return -EIO;
 69	obj = (union acpi_object *)output.pointer;
 70	if (obj->type != ACPI_TYPE_BUFFER) {
 71		dev_dbg(&wdev->dev, "received type: %d\n", obj->type);
 72		if (obj->type == ACPI_TYPE_INTEGER)
 73			dev_dbg(&wdev->dev, "SMBIOS call failed: %llu\n",
 74				obj->integer.value);
 75		return -EIO;
 76	}
 77	memcpy(&priv->buf->std, obj->buffer.pointer, obj->buffer.length);
 78	dev_dbg(&wdev->dev, "result: [%08x,%08x,%08x,%08x]\n",
 79		priv->buf->std.output[0], priv->buf->std.output[1],
 80		priv->buf->std.output[2], priv->buf->std.output[3]);
 81
 82	return 0;
 83}
 84
 85int dell_smbios_wmi_call(struct calling_interface_buffer *buffer)
 86{
 87	struct wmi_smbios_priv *priv;
 88	size_t difference;
 89	size_t size;
 90	int ret;
 91
 92	mutex_lock(&call_mutex);
 93	priv = get_first_smbios_priv();
 94	if (!priv) {
 95		ret = -ENODEV;
 96		goto out_wmi_call;
 97	}
 98
 99	size = sizeof(struct calling_interface_buffer);
100	difference = priv->req_buf_size - sizeof(u64) - size;
101
102	memset(&priv->buf->ext, 0, difference);
103	memcpy(&priv->buf->std, buffer, size);
104	ret = run_smbios_call(priv->wdev);
105	memcpy(buffer, &priv->buf->std, size);
106out_wmi_call:
107	mutex_unlock(&call_mutex);
108
109	return ret;
110}
111
112static long dell_smbios_wmi_filter(struct wmi_device *wdev, unsigned int cmd,
113				   struct wmi_ioctl_buffer *arg)
114{
115	struct wmi_smbios_priv *priv;
116	int ret = 0;
117
118	switch (cmd) {
119	case DELL_WMI_SMBIOS_CMD:
120		mutex_lock(&call_mutex);
121		priv = dev_get_drvdata(&wdev->dev);
122		if (!priv) {
123			ret = -ENODEV;
124			goto fail_smbios_cmd;
125		}
126		memcpy(priv->buf, arg, priv->req_buf_size);
127		if (dell_smbios_call_filter(&wdev->dev, &priv->buf->std)) {
128			dev_err(&wdev->dev, "Invalid call %d/%d:%8x\n",
129				priv->buf->std.cmd_class,
130				priv->buf->std.cmd_select,
131				priv->buf->std.input[0]);
132			ret = -EFAULT;
133			goto fail_smbios_cmd;
134		}
135		ret = run_smbios_call(priv->wdev);
136		if (ret)
137			goto fail_smbios_cmd;
138		memcpy(arg, priv->buf, priv->req_buf_size);
139fail_smbios_cmd:
140		mutex_unlock(&call_mutex);
141		break;
142	default:
143		ret = -ENOIOCTLCMD;
144	}
145	return ret;
146}
147
148static int dell_smbios_wmi_probe(struct wmi_device *wdev)
149{
150	struct wmi_driver *wdriver =
151		container_of(wdev->dev.driver, struct wmi_driver, driver);
152	struct wmi_smbios_priv *priv;
153	u32 hotfix;
154	int count;
155	int ret;
156
157	ret = dell_wmi_get_descriptor_valid();
158	if (ret)
159		return ret;
160
161	priv = devm_kzalloc(&wdev->dev, sizeof(struct wmi_smbios_priv),
162			    GFP_KERNEL);
163	if (!priv)
164		return -ENOMEM;
165
166	/* WMI buffer size will be either 4k or 32k depending on machine */
167	if (!dell_wmi_get_size(&priv->req_buf_size))
168		return -EPROBE_DEFER;
169
170	/* some SMBIOS calls fail unless BIOS contains hotfix */
171	if (!dell_wmi_get_hotfix(&hotfix))
172		return -EPROBE_DEFER;
173	if (!hotfix) {
174		dev_warn(&wdev->dev,
175			"WMI SMBIOS userspace interface not supported(%u), try upgrading to a newer BIOS\n",
176			hotfix);
177		wdriver->filter_callback = NULL;
178	}
179
180	/* add in the length object we will use internally with ioctl */
181	priv->req_buf_size += sizeof(u64);
182	ret = set_required_buffer_size(wdev, priv->req_buf_size);
183	if (ret)
184		return ret;
185
186	count = get_order(priv->req_buf_size);
187	priv->buf = (void *)__get_free_pages(GFP_KERNEL, count);
188	if (!priv->buf)
189		return -ENOMEM;
190
191	/* ID is used by dell-smbios to set priority of drivers */
192	wdev->dev.id = 1;
193	ret = dell_smbios_register_device(&wdev->dev, &dell_smbios_wmi_call);
194	if (ret)
195		goto fail_register;
196
197	priv->wdev = wdev;
198	dev_set_drvdata(&wdev->dev, priv);
199	mutex_lock(&list_mutex);
200	list_add_tail(&priv->list, &wmi_list);
201	mutex_unlock(&list_mutex);
202
203	return 0;
204
205fail_register:
206	free_pages((unsigned long)priv->buf, count);
207	return ret;
208}
209
210static int dell_smbios_wmi_remove(struct wmi_device *wdev)
211{
212	struct wmi_smbios_priv *priv = dev_get_drvdata(&wdev->dev);
213	int count;
214
215	mutex_lock(&call_mutex);
216	mutex_lock(&list_mutex);
217	list_del(&priv->list);
218	mutex_unlock(&list_mutex);
219	dell_smbios_unregister_device(&wdev->dev);
220	count = get_order(priv->req_buf_size);
221	free_pages((unsigned long)priv->buf, count);
222	mutex_unlock(&call_mutex);
223	return 0;
224}
225
226static const struct wmi_device_id dell_smbios_wmi_id_table[] = {
227	{ .guid_string = DELL_WMI_SMBIOS_GUID },
228	{ },
229};
230
231static void parse_b1_table(const struct dmi_header *dm)
232{
233	struct misc_bios_flags_structure *flags =
234	container_of(dm, struct misc_bios_flags_structure, header);
235
236	/* 4 bytes header, 8 bytes flags */
237	if (dm->length < 12)
238		return;
239	if (dm->handle != 0xb100)
240		return;
241	if ((flags->flags0 & FLAG_HAS_ACPI_WMI))
242		wmi_supported = 1;
243}
244
245static void find_b1(const struct dmi_header *dm, void *dummy)
246{
247	switch (dm->type) {
248	case 0xb1: /* misc bios flags */
249		parse_b1_table(dm);
250		break;
251	}
252}
253
254static struct wmi_driver dell_smbios_wmi_driver = {
255	.driver = {
256		.name = "dell-smbios",
257	},
258	.probe = dell_smbios_wmi_probe,
259	.remove = dell_smbios_wmi_remove,
260	.id_table = dell_smbios_wmi_id_table,
261	.filter_callback = dell_smbios_wmi_filter,
262};
263
264int init_dell_smbios_wmi(void)
265{
266	dmi_walk(find_b1, NULL);
267
268	if (!wmi_supported)
269		return -ENODEV;
270
271	return wmi_driver_register(&dell_smbios_wmi_driver);
272}
273
274void exit_dell_smbios_wmi(void)
275{
276	wmi_driver_unregister(&dell_smbios_wmi_driver);
277}
278
279MODULE_ALIAS("wmi:" DELL_WMI_SMBIOS_GUID);