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,u8 idx)26 static bool is_link_enabled(struct fwnode_handle *fw_node, u8 idx)
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-%hhu-subproperties", idx);
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 fwnode_handle_put(link);
45
46 if (quirk_mask & SDW_INTEL_QUIRK_MASK_BUS_DISABLE)
47 return false;
48
49 return true;
50 }
51
52 static int
sdw_intel_scan_controller(struct sdw_intel_acpi_info * info)53 sdw_intel_scan_controller(struct sdw_intel_acpi_info *info)
54 {
55 struct acpi_device *adev = acpi_fetch_acpi_dev(info->handle);
56 u8 count, i;
57 int ret;
58
59 if (!adev)
60 return -EINVAL;
61
62 /* Found controller, find links supported */
63 count = 0;
64 ret = fwnode_property_read_u8_array(acpi_fwnode_handle(adev),
65 "mipi-sdw-master-count", &count, 1);
66
67 /*
68 * In theory we could check the number of links supported in
69 * hardware, but in that step we cannot assume SoundWire IP is
70 * powered.
71 *
72 * In addition, if the BIOS doesn't even provide this
73 * 'master-count' property then all the inits based on link
74 * masks will fail as well.
75 *
76 * We will check the hardware capabilities in the startup() step
77 */
78
79 if (ret) {
80 dev_err(&adev->dev,
81 "Failed to read mipi-sdw-master-count: %d\n", ret);
82 return -EINVAL;
83 }
84
85 /* Check count is within bounds */
86 if (count > SDW_MAX_LINKS) {
87 dev_err(&adev->dev, "Link count %d exceeds max %d\n",
88 count, SDW_MAX_LINKS);
89 return -EINVAL;
90 }
91
92 if (!count) {
93 dev_warn(&adev->dev, "No SoundWire links detected\n");
94 return -EINVAL;
95 }
96 dev_dbg(&adev->dev, "ACPI reports %d SDW Link devices\n", count);
97
98 info->count = count;
99 info->link_mask = 0;
100
101 for (i = 0; i < count; i++) {
102 if (ctrl_link_mask && !(ctrl_link_mask & BIT(i))) {
103 dev_dbg(&adev->dev,
104 "Link %d masked, will not be enabled\n", i);
105 continue;
106 }
107
108 if (!is_link_enabled(acpi_fwnode_handle(adev), i)) {
109 dev_dbg(&adev->dev,
110 "Link %d not selected in firmware\n", i);
111 continue;
112 }
113
114 info->link_mask |= BIT(i);
115 }
116
117 return 0;
118 }
119
sdw_intel_acpi_cb(acpi_handle handle,u32 level,void * cdata,void ** return_value)120 static acpi_status sdw_intel_acpi_cb(acpi_handle handle, u32 level,
121 void *cdata, void **return_value)
122 {
123 struct sdw_intel_acpi_info *info = cdata;
124 acpi_status status;
125 u64 adr;
126
127 status = acpi_evaluate_integer(handle, METHOD_NAME__ADR, NULL, &adr);
128 if (ACPI_FAILURE(status))
129 return AE_OK; /* keep going */
130
131 if (!acpi_fetch_acpi_dev(handle)) {
132 pr_err("%s: Couldn't find ACPI handle\n", __func__);
133 return AE_NOT_FOUND;
134 }
135
136 /*
137 * On some Intel platforms, multiple children of the HDAS
138 * device can be found, but only one of them is the SoundWire
139 * controller. The SNDW device is always exposed with
140 * Name(_ADR, 0x40000000), with bits 31..28 representing the
141 * SoundWire link so filter accordingly
142 */
143 if (FIELD_GET(GENMASK(31, 28), adr) != SDW_LINK_TYPE)
144 return AE_OK; /* keep going */
145
146 /* found the correct SoundWire controller */
147 info->handle = handle;
148
149 /* device found, stop namespace walk */
150 return AE_CTRL_TERMINATE;
151 }
152
153 /**
154 * sdw_intel_acpi_scan() - SoundWire Intel init routine
155 * @parent_handle: ACPI parent handle
156 * @info: description of what firmware/DSDT tables expose
157 *
158 * This scans the namespace and queries firmware to figure out which
159 * links to enable. A follow-up use of sdw_intel_probe() and
160 * sdw_intel_startup() is required for creation of devices and bus
161 * startup
162 */
sdw_intel_acpi_scan(acpi_handle * parent_handle,struct sdw_intel_acpi_info * info)163 int sdw_intel_acpi_scan(acpi_handle *parent_handle,
164 struct sdw_intel_acpi_info *info)
165 {
166 acpi_status status;
167
168 info->handle = NULL;
169 /*
170 * In the HDAS ACPI scope, 'SNDW' may be either the child of
171 * 'HDAS' or the grandchild of 'HDAS'. So let's go through
172 * the ACPI from 'HDAS' at max depth of 2 to find the 'SNDW'
173 * device.
174 */
175 status = acpi_walk_namespace(ACPI_TYPE_DEVICE,
176 parent_handle, 2,
177 sdw_intel_acpi_cb,
178 NULL, info, NULL);
179 if (ACPI_FAILURE(status) || info->handle == NULL)
180 return -ENODEV;
181
182 return sdw_intel_scan_controller(info);
183 }
184 EXPORT_SYMBOL_NS(sdw_intel_acpi_scan, SND_INTEL_SOUNDWIRE_ACPI);
185
186 MODULE_LICENSE("Dual BSD/GPL");
187 MODULE_DESCRIPTION("Intel Soundwire ACPI helpers");
188