1 // SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
2 // Copyright(c) 2015-2021 Intel Corporation.
3
4 /*
5 * SDW Intel ACPI scan helpers
6 */
7
8 #include <linux/acpi.h>
9 #include <linux/bits.h>
10 #include <linux/bitfield.h>
11 #include <linux/device.h>
12 #include <linux/errno.h>
13 #include <linux/export.h>
14 #include <linux/fwnode.h>
15 #include <linux/module.h>
16 #include <linux/soundwire/sdw_intel.h>
17 #include <linux/string.h>
18
19 #define SDW_LINK_TYPE 4 /* from Intel ACPI documentation */
20 #define SDW_MAX_LINKS 4
21
22 static int ctrl_link_mask;
23 module_param_named(sdw_link_mask, ctrl_link_mask, int, 0444);
24 MODULE_PARM_DESC(sdw_link_mask, "Intel link mask (one bit per link)");
25
is_link_enabled(struct fwnode_handle * fw_node,int i)26 static bool is_link_enabled(struct fwnode_handle *fw_node, int i)
27 {
28 struct fwnode_handle *link;
29 char name[32];
30 u32 quirk_mask = 0;
31
32 /* Find master handle */
33 snprintf(name, sizeof(name),
34 "mipi-sdw-link-%d-subproperties", i);
35
36 link = fwnode_get_named_child_node(fw_node, name);
37 if (!link)
38 return false;
39
40 fwnode_property_read_u32(link,
41 "intel-quirk-mask",
42 &quirk_mask);
43
44 if (quirk_mask & SDW_INTEL_QUIRK_MASK_BUS_DISABLE)
45 return false;
46
47 return true;
48 }
49
50 static int
sdw_intel_scan_controller(struct sdw_intel_acpi_info * info)51 sdw_intel_scan_controller(struct sdw_intel_acpi_info *info)
52 {
53 struct acpi_device *adev;
54 int ret, i;
55 u8 count;
56
57 if (acpi_bus_get_device(info->handle, &adev))
58 return -EINVAL;
59
60 /* Found controller, find links supported */
61 count = 0;
62 ret = fwnode_property_read_u8_array(acpi_fwnode_handle(adev),
63 "mipi-sdw-master-count", &count, 1);
64
65 /*
66 * In theory we could check the number of links supported in
67 * hardware, but in that step we cannot assume SoundWire IP is
68 * powered.
69 *
70 * In addition, if the BIOS doesn't even provide this
71 * 'master-count' property then all the inits based on link
72 * masks will fail as well.
73 *
74 * We will check the hardware capabilities in the startup() step
75 */
76
77 if (ret) {
78 dev_err(&adev->dev,
79 "Failed to read mipi-sdw-master-count: %d\n", ret);
80 return -EINVAL;
81 }
82
83 /* Check count is within bounds */
84 if (count > SDW_MAX_LINKS) {
85 dev_err(&adev->dev, "Link count %d exceeds max %d\n",
86 count, SDW_MAX_LINKS);
87 return -EINVAL;
88 }
89
90 if (!count) {
91 dev_warn(&adev->dev, "No SoundWire links detected\n");
92 return -EINVAL;
93 }
94 dev_dbg(&adev->dev, "ACPI reports %d SDW Link devices\n", count);
95
96 info->count = count;
97 info->link_mask = 0;
98
99 for (i = 0; i < count; i++) {
100 if (ctrl_link_mask && !(ctrl_link_mask & BIT(i))) {
101 dev_dbg(&adev->dev,
102 "Link %d masked, will not be enabled\n", i);
103 continue;
104 }
105
106 if (!is_link_enabled(acpi_fwnode_handle(adev), i)) {
107 dev_dbg(&adev->dev,
108 "Link %d not selected in firmware\n", i);
109 continue;
110 }
111
112 info->link_mask |= BIT(i);
113 }
114
115 return 0;
116 }
117
sdw_intel_acpi_cb(acpi_handle handle,u32 level,void * cdata,void ** return_value)118 static acpi_status sdw_intel_acpi_cb(acpi_handle handle, u32 level,
119 void *cdata, void **return_value)
120 {
121 struct sdw_intel_acpi_info *info = cdata;
122 struct acpi_device *adev;
123 acpi_status status;
124 u64 adr;
125
126 status = acpi_evaluate_integer(handle, METHOD_NAME__ADR, NULL, &adr);
127 if (ACPI_FAILURE(status))
128 return AE_OK; /* keep going */
129
130 if (acpi_bus_get_device(handle, &adev)) {
131 pr_err("%s: Couldn't find ACPI handle\n", __func__);
132 return AE_NOT_FOUND;
133 }
134
135 /*
136 * On some Intel platforms, multiple children of the HDAS
137 * device can be found, but only one of them is the SoundWire
138 * controller. The SNDW device is always exposed with
139 * Name(_ADR, 0x40000000), with bits 31..28 representing the
140 * SoundWire link so filter accordingly
141 */
142 if (FIELD_GET(GENMASK(31, 28), adr) != SDW_LINK_TYPE)
143 return AE_OK; /* keep going */
144
145 /* found the correct SoundWire controller */
146 info->handle = handle;
147
148 /* device found, stop namespace walk */
149 return AE_CTRL_TERMINATE;
150 }
151
152 /**
153 * sdw_intel_acpi_scan() - SoundWire Intel init routine
154 * @parent_handle: ACPI parent handle
155 * @info: description of what firmware/DSDT tables expose
156 *
157 * This scans the namespace and queries firmware to figure out which
158 * links to enable. A follow-up use of sdw_intel_probe() and
159 * sdw_intel_startup() is required for creation of devices and bus
160 * startup
161 */
sdw_intel_acpi_scan(acpi_handle * parent_handle,struct sdw_intel_acpi_info * info)162 int sdw_intel_acpi_scan(acpi_handle *parent_handle,
163 struct sdw_intel_acpi_info *info)
164 {
165 acpi_status status;
166
167 info->handle = NULL;
168 /*
169 * In the HDAS ACPI scope, 'SNDW' may be either the child of
170 * 'HDAS' or the grandchild of 'HDAS'. So let's go through
171 * the ACPI from 'HDAS' at max depth of 2 to find the 'SNDW'
172 * device.
173 */
174 status = acpi_walk_namespace(ACPI_TYPE_DEVICE,
175 parent_handle, 2,
176 sdw_intel_acpi_cb,
177 NULL, info, NULL);
178 if (ACPI_FAILURE(status) || info->handle == NULL)
179 return -ENODEV;
180
181 return sdw_intel_scan_controller(info);
182 }
183 EXPORT_SYMBOL_NS(sdw_intel_acpi_scan, SND_INTEL_SOUNDWIRE_ACPI);
184
185 MODULE_LICENSE("Dual BSD/GPL");
186 MODULE_DESCRIPTION("Intel Soundwire ACPI helpers");
187