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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Slim Bootloader(SBL) firmware update signaling driver
4 *
5 * Slim Bootloader is a small, open-source, non UEFI compliant, boot firmware
6 * optimized for running on certain Intel platforms.
7 *
8 * SBL exposes an ACPI-WMI device via /sys/bus/wmi/devices/<INTEL_WMI_SBL_GUID>.
9 * This driver further adds "firmware_update_request" device attribute.
10 * This attribute normally has a value of 0 and userspace can signal SBL
11 * to update firmware, on next reboot, by writing a value of 1.
12 *
13 * More details of SBL firmware update process is available at:
14 * https://slimbootloader.github.io/security/firmware-update.html
15 */
16
17#include <linux/acpi.h>
18#include <linux/device.h>
19#include <linux/module.h>
20#include <linux/slab.h>
21#include <linux/sysfs.h>
22#include <linux/wmi.h>
23
24#define INTEL_WMI_SBL_GUID "44FADEB1-B204-40F2-8581-394BBDC1B651"
25
26static int get_fwu_request(struct device *dev, u32 *out)
27{
28 struct acpi_buffer result = {ACPI_ALLOCATE_BUFFER, NULL};
29 union acpi_object *obj;
30 acpi_status status;
31
32 status = wmi_query_block(INTEL_WMI_SBL_GUID, 0, &result);
33 if (ACPI_FAILURE(status)) {
34 dev_err(dev, "wmi_query_block failed\n");
35 return -ENODEV;
36 }
37
38 obj = (union acpi_object *)result.pointer;
39 if (!obj || obj->type != ACPI_TYPE_INTEGER) {
40 dev_warn(dev, "wmi_query_block returned invalid value\n");
41 kfree(obj);
42 return -EINVAL;
43 }
44
45 *out = obj->integer.value;
46 kfree(obj);
47
48 return 0;
49}
50
51static int set_fwu_request(struct device *dev, u32 in)
52{
53 struct acpi_buffer input;
54 acpi_status status;
55 u32 value;
56
57 value = in;
58 input.length = sizeof(u32);
59 input.pointer = &value;
60
61 status = wmi_set_block(INTEL_WMI_SBL_GUID, 0, &input);
62 if (ACPI_FAILURE(status)) {
63 dev_err(dev, "wmi_set_block failed\n");
64 return -ENODEV;
65 }
66
67 return 0;
68}
69
70static ssize_t firmware_update_request_show(struct device *dev,
71 struct device_attribute *attr,
72 char *buf)
73{
74 u32 val;
75 int ret;
76
77 ret = get_fwu_request(dev, &val);
78 if (ret)
79 return ret;
80
81 return sprintf(buf, "%d\n", val);
82}
83
84static ssize_t firmware_update_request_store(struct device *dev,
85 struct device_attribute *attr,
86 const char *buf, size_t count)
87{
88 unsigned int val;
89 int ret;
90
91 ret = kstrtouint(buf, 0, &val);
92 if (ret)
93 return ret;
94
95 /* May later be extended to support values other than 0 and 1 */
96 if (val > 1)
97 return -ERANGE;
98
99 ret = set_fwu_request(dev, val);
100 if (ret)
101 return ret;
102
103 return count;
104}
105static DEVICE_ATTR_RW(firmware_update_request);
106
107static struct attribute *firmware_update_attrs[] = {
108 &dev_attr_firmware_update_request.attr,
109 NULL
110};
111ATTRIBUTE_GROUPS(firmware_update);
112
113static int intel_wmi_sbl_fw_update_probe(struct wmi_device *wdev,
114 const void *context)
115{
116 dev_info(&wdev->dev, "Slim Bootloader signaling driver attached\n");
117 return 0;
118}
119
120static void intel_wmi_sbl_fw_update_remove(struct wmi_device *wdev)
121{
122 dev_info(&wdev->dev, "Slim Bootloader signaling driver removed\n");
123}
124
125static const struct wmi_device_id intel_wmi_sbl_id_table[] = {
126 { .guid_string = INTEL_WMI_SBL_GUID },
127 {}
128};
129MODULE_DEVICE_TABLE(wmi, intel_wmi_sbl_id_table);
130
131static struct wmi_driver intel_wmi_sbl_fw_update_driver = {
132 .driver = {
133 .name = "intel-wmi-sbl-fw-update",
134 .dev_groups = firmware_update_groups,
135 },
136 .probe = intel_wmi_sbl_fw_update_probe,
137 .remove = intel_wmi_sbl_fw_update_remove,
138 .id_table = intel_wmi_sbl_id_table,
139};
140module_wmi_driver(intel_wmi_sbl_fw_update_driver);
141
142MODULE_AUTHOR("Jithu Joseph <jithu.joseph@intel.com>");
143MODULE_DESCRIPTION("Slim Bootloader firmware update signaling driver");
144MODULE_LICENSE("GPL v2");
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Slim Bootloader(SBL) firmware update signaling driver
4 *
5 * Slim Bootloader is a small, open-source, non UEFI compliant, boot firmware
6 * optimized for running on certain Intel platforms.
7 *
8 * SBL exposes an ACPI-WMI device via /sys/bus/wmi/devices/<INTEL_WMI_SBL_GUID>.
9 * This driver further adds "firmware_update_request" device attribute.
10 * This attribute normally has a value of 0 and userspace can signal SBL
11 * to update firmware, on next reboot, by writing a value of 1.
12 *
13 * More details of SBL firmware update process is available at:
14 * https://slimbootloader.github.io/security/firmware-update.html
15 */
16
17#include <linux/acpi.h>
18#include <linux/device.h>
19#include <linux/module.h>
20#include <linux/slab.h>
21#include <linux/sysfs.h>
22#include <linux/wmi.h>
23
24#define INTEL_WMI_SBL_GUID "44FADEB1-B204-40F2-8581-394BBDC1B651"
25
26static int get_fwu_request(struct device *dev, u32 *out)
27{
28 union acpi_object *obj;
29
30 obj = wmidev_block_query(to_wmi_device(dev), 0);
31 if (!obj)
32 return -ENODEV;
33
34 if (obj->type != ACPI_TYPE_INTEGER) {
35 dev_warn(dev, "wmidev_block_query returned invalid value\n");
36 kfree(obj);
37 return -EINVAL;
38 }
39
40 *out = obj->integer.value;
41 kfree(obj);
42
43 return 0;
44}
45
46static int set_fwu_request(struct device *dev, u32 in)
47{
48 struct acpi_buffer input;
49 acpi_status status;
50 u32 value;
51
52 value = in;
53 input.length = sizeof(u32);
54 input.pointer = &value;
55
56 status = wmidev_block_set(to_wmi_device(dev), 0, &input);
57 if (ACPI_FAILURE(status)) {
58 dev_err(dev, "wmidev_block_set failed\n");
59 return -ENODEV;
60 }
61
62 return 0;
63}
64
65static ssize_t firmware_update_request_show(struct device *dev,
66 struct device_attribute *attr,
67 char *buf)
68{
69 u32 val;
70 int ret;
71
72 ret = get_fwu_request(dev, &val);
73 if (ret)
74 return ret;
75
76 return sprintf(buf, "%d\n", val);
77}
78
79static ssize_t firmware_update_request_store(struct device *dev,
80 struct device_attribute *attr,
81 const char *buf, size_t count)
82{
83 unsigned int val;
84 int ret;
85
86 ret = kstrtouint(buf, 0, &val);
87 if (ret)
88 return ret;
89
90 /* May later be extended to support values other than 0 and 1 */
91 if (val > 1)
92 return -ERANGE;
93
94 ret = set_fwu_request(dev, val);
95 if (ret)
96 return ret;
97
98 return count;
99}
100static DEVICE_ATTR_RW(firmware_update_request);
101
102static struct attribute *firmware_update_attrs[] = {
103 &dev_attr_firmware_update_request.attr,
104 NULL
105};
106ATTRIBUTE_GROUPS(firmware_update);
107
108static int intel_wmi_sbl_fw_update_probe(struct wmi_device *wdev,
109 const void *context)
110{
111 dev_info(&wdev->dev, "Slim Bootloader signaling driver attached\n");
112 return 0;
113}
114
115static void intel_wmi_sbl_fw_update_remove(struct wmi_device *wdev)
116{
117 dev_info(&wdev->dev, "Slim Bootloader signaling driver removed\n");
118}
119
120static const struct wmi_device_id intel_wmi_sbl_id_table[] = {
121 { .guid_string = INTEL_WMI_SBL_GUID },
122 {}
123};
124MODULE_DEVICE_TABLE(wmi, intel_wmi_sbl_id_table);
125
126static struct wmi_driver intel_wmi_sbl_fw_update_driver = {
127 .driver = {
128 .name = "intel-wmi-sbl-fw-update",
129 .dev_groups = firmware_update_groups,
130 },
131 .probe = intel_wmi_sbl_fw_update_probe,
132 .remove = intel_wmi_sbl_fw_update_remove,
133 .id_table = intel_wmi_sbl_id_table,
134 .no_singleton = true,
135};
136module_wmi_driver(intel_wmi_sbl_fw_update_driver);
137
138MODULE_AUTHOR("Jithu Joseph <jithu.joseph@intel.com>");
139MODULE_DESCRIPTION("Slim Bootloader firmware update signaling driver");
140MODULE_LICENSE("GPL v2");