1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 *  WMI methods for use with dell-smbios
  4 *
  5 *  Copyright (c) 2017 Dell Inc.
  6 */
  7#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  8
  9#include <linux/dmi.h>
 10#include <linux/list.h>
 11#include <linux/module.h>
 12#include <linux/mutex.h>
 13#include <linux/uaccess.h>
 14#include <linux/wmi.h>
 15#include "dell-smbios.h"
 16#include "dell-wmi-descriptor.h"
 17
 18static DEFINE_MUTEX(call_mutex);
 19static DEFINE_MUTEX(list_mutex);
 20static int wmi_supported;
 21
 22struct misc_bios_flags_structure {
 23	struct dmi_header header;
 24	u16 flags0;
 25} __packed;
 26#define FLAG_HAS_ACPI_WMI 0x02
 27
 28#define DELL_WMI_SMBIOS_GUID "A80593CE-A997-11DA-B012-B622A1EF5492"
 29
 30struct wmi_smbios_priv {
 31	struct dell_wmi_smbios_buffer *buf;
 32	struct list_head list;
 33	struct wmi_device *wdev;
 34	struct device *child;
 35	u32 req_buf_size;
 36};
 37static LIST_HEAD(wmi_list);
 38
 39static inline struct wmi_smbios_priv *get_first_smbios_priv(void)
 40{
 41	return list_first_entry_or_null(&wmi_list,
 42					struct wmi_smbios_priv,
 43					list);
 44}
 45
 46static int run_smbios_call(struct wmi_device *wdev)
 47{
 48	struct acpi_buffer output = {ACPI_ALLOCATE_BUFFER, NULL};
 49	struct wmi_smbios_priv *priv;
 50	struct acpi_buffer input;
 51	union acpi_object *obj;
 52	acpi_status status;
 53
 54	priv = dev_get_drvdata(&wdev->dev);
 55	input.length = priv->req_buf_size - sizeof(u64);
 56	input.pointer = &priv->buf->std;
 57
 58	dev_dbg(&wdev->dev, "evaluating: %u/%u [%x,%x,%x,%x]\n",
 59		priv->buf->std.cmd_class, priv->buf->std.cmd_select,
 60		priv->buf->std.input[0], priv->buf->std.input[1],
 61		priv->buf->std.input[2], priv->buf->std.input[3]);
 62
 63	status = wmidev_evaluate_method(wdev, 0, 1, &input, &output);
 64	if (ACPI_FAILURE(status))
 65		return -EIO;
 66	obj = (union acpi_object *)output.pointer;
 67	if (obj->type != ACPI_TYPE_BUFFER) {
 68		dev_dbg(&wdev->dev, "received type: %d\n", obj->type);
 69		if (obj->type == ACPI_TYPE_INTEGER)
 70			dev_dbg(&wdev->dev, "SMBIOS call failed: %llu\n",
 71				obj->integer.value);
 72		return -EIO;
 73	}
 74	memcpy(&priv->buf->std, obj->buffer.pointer, obj->buffer.length);
 75	dev_dbg(&wdev->dev, "result: [%08x,%08x,%08x,%08x]\n",
 76		priv->buf->std.output[0], priv->buf->std.output[1],
 77		priv->buf->std.output[2], priv->buf->std.output[3]);
 78	kfree(output.pointer);
 79
 80	return 0;
 81}
 82
 83static int dell_smbios_wmi_call(struct calling_interface_buffer *buffer)
 84{
 85	struct wmi_smbios_priv *priv;
 86	size_t difference;
 87	size_t size;
 88	int ret;
 89
 90	mutex_lock(&call_mutex);
 91	priv = get_first_smbios_priv();
 92	if (!priv) {
 93		ret = -ENODEV;
 94		goto out_wmi_call;
 95	}
 96
 97	size = sizeof(struct calling_interface_buffer);
 98	difference = priv->req_buf_size - sizeof(u64) - size;
 99
100	memset(&priv->buf->ext, 0, difference);
101	memcpy(&priv->buf->std, buffer, size);
102	ret = run_smbios_call(priv->wdev);
103	memcpy(buffer, &priv->buf->std, size);
104out_wmi_call:
105	mutex_unlock(&call_mutex);
106
107	return ret;
108}
109
110static long dell_smbios_wmi_filter(struct wmi_device *wdev, unsigned int cmd,
111				   struct wmi_ioctl_buffer *arg)
112{
113	struct wmi_smbios_priv *priv;
114	int ret = 0;
115
116	switch (cmd) {
117	case DELL_WMI_SMBIOS_CMD:
118		mutex_lock(&call_mutex);
119		priv = dev_get_drvdata(&wdev->dev);
120		if (!priv) {
121			ret = -ENODEV;
122			goto fail_smbios_cmd;
123		}
124		memcpy(priv->buf, arg, priv->req_buf_size);
125		if (dell_smbios_call_filter(&wdev->dev, &priv->buf->std)) {
126			dev_err(&wdev->dev, "Invalid call %d/%d:%8x\n",
127				priv->buf->std.cmd_class,
128				priv->buf->std.cmd_select,
129				priv->buf->std.input[0]);
130			ret = -EFAULT;
131			goto fail_smbios_cmd;
132		}
133		ret = run_smbios_call(priv->wdev);
134		if (ret)
135			goto fail_smbios_cmd;
136		memcpy(arg, priv->buf, priv->req_buf_size);
137fail_smbios_cmd:
138		mutex_unlock(&call_mutex);
139		break;
140	default:
141		ret = -ENOIOCTLCMD;
142	}
143	return ret;
144}
145
146static int dell_smbios_wmi_probe(struct wmi_device *wdev, const void *context)
147{
148	struct wmi_driver *wdriver =
149		container_of(wdev->dev.driver, struct wmi_driver, driver);
150	struct wmi_smbios_priv *priv;
151	u32 hotfix;
152	int count;
153	int ret;
154
155	ret = dell_wmi_get_descriptor_valid();
156	if (ret)
157		return ret;
158
159	priv = devm_kzalloc(&wdev->dev, sizeof(struct wmi_smbios_priv),
160			    GFP_KERNEL);
161	if (!priv)
162		return -ENOMEM;
163
164	/* WMI buffer size will be either 4k or 32k depending on machine */
165	if (!dell_wmi_get_size(&priv->req_buf_size))
166		return -EPROBE_DEFER;
167
168	/* some SMBIOS calls fail unless BIOS contains hotfix */
169	if (!dell_wmi_get_hotfix(&hotfix))
170		return -EPROBE_DEFER;
171	if (!hotfix) {
172		dev_warn(&wdev->dev,
173			"WMI SMBIOS userspace interface not supported(%u), try upgrading to a newer BIOS\n",
174			hotfix);
175		wdriver->filter_callback = NULL;
176	}
177
178	/* add in the length object we will use internally with ioctl */
179	priv->req_buf_size += sizeof(u64);
180	ret = set_required_buffer_size(wdev, priv->req_buf_size);
181	if (ret)
182		return ret;
183
184	count = get_order(priv->req_buf_size);
185	priv->buf = (void *)__get_free_pages(GFP_KERNEL, count);
186	if (!priv->buf)
187		return -ENOMEM;
188
189	/* ID is used by dell-smbios to set priority of drivers */
190	wdev->dev.id = 1;
191	ret = dell_smbios_register_device(&wdev->dev, &dell_smbios_wmi_call);
192	if (ret)
193		goto fail_register;
194
195	priv->wdev = wdev;
196	dev_set_drvdata(&wdev->dev, priv);
197	mutex_lock(&list_mutex);
198	list_add_tail(&priv->list, &wmi_list);
199	mutex_unlock(&list_mutex);
200
201	return 0;
202
203fail_register:
204	free_pages((unsigned long)priv->buf, count);
205	return ret;
206}
207
208static int dell_smbios_wmi_remove(struct wmi_device *wdev)
209{
210	struct wmi_smbios_priv *priv = dev_get_drvdata(&wdev->dev);
211	int count;
212
213	mutex_lock(&call_mutex);
214	mutex_lock(&list_mutex);
215	list_del(&priv->list);
216	mutex_unlock(&list_mutex);
217	dell_smbios_unregister_device(&wdev->dev);
218	count = get_order(priv->req_buf_size);
219	free_pages((unsigned long)priv->buf, count);
220	mutex_unlock(&call_mutex);
221	return 0;
222}
223
224static const struct wmi_device_id dell_smbios_wmi_id_table[] = {
225	{ .guid_string = DELL_WMI_SMBIOS_GUID },
226	{ },
227};
228
229static void parse_b1_table(const struct dmi_header *dm)
230{
231	struct misc_bios_flags_structure *flags =
232	container_of(dm, struct misc_bios_flags_structure, header);
233
234	/* 4 bytes header, 8 bytes flags */
235	if (dm->length < 12)
236		return;
237	if (dm->handle != 0xb100)
238		return;
239	if ((flags->flags0 & FLAG_HAS_ACPI_WMI))
240		wmi_supported = 1;
241}
242
243static void find_b1(const struct dmi_header *dm, void *dummy)
244{
245	switch (dm->type) {
246	case 0xb1: /* misc bios flags */
247		parse_b1_table(dm);
248		break;
249	}
250}
251
252static struct wmi_driver dell_smbios_wmi_driver = {
253	.driver = {
254		.name = "dell-smbios",
255	},
256	.probe = dell_smbios_wmi_probe,
257	.remove = dell_smbios_wmi_remove,
258	.id_table = dell_smbios_wmi_id_table,
259	.filter_callback = dell_smbios_wmi_filter,
260};
261
262int init_dell_smbios_wmi(void)
263{
264	dmi_walk(find_b1, NULL);
265
266	if (!wmi_supported)
267		return -ENODEV;
268
269	return wmi_driver_register(&dell_smbios_wmi_driver);
270}
271
272void exit_dell_smbios_wmi(void)
273{
274	wmi_driver_unregister(&dell_smbios_wmi_driver);
275}
276
277MODULE_DEVICE_TABLE(wmi, dell_smbios_wmi_id_table);