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 = acpi_fetch_acpi_dev(info->handle);
54 	int ret, i;
55 	u8 count;
56 
57 	if (!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 	acpi_status status;
123 	u64 adr;
124 
125 	status = acpi_evaluate_integer(handle, METHOD_NAME__ADR, NULL, &adr);
126 	if (ACPI_FAILURE(status))
127 		return AE_OK; /* keep going */
128 
129 	if (!acpi_fetch_acpi_dev(handle)) {
130 		pr_err("%s: Couldn't find ACPI handle\n", __func__);
131 		return AE_NOT_FOUND;
132 	}
133 
134 	/*
135 	 * On some Intel platforms, multiple children of the HDAS
136 	 * device can be found, but only one of them is the SoundWire
137 	 * controller. The SNDW device is always exposed with
138 	 * Name(_ADR, 0x40000000), with bits 31..28 representing the
139 	 * SoundWire link so filter accordingly
140 	 */
141 	if (FIELD_GET(GENMASK(31, 28), adr) != SDW_LINK_TYPE)
142 		return AE_OK; /* keep going */
143 
144 	/* found the correct SoundWire controller */
145 	info->handle = handle;
146 
147 	/* device found, stop namespace walk */
148 	return AE_CTRL_TERMINATE;
149 }
150 
151 /**
152  * sdw_intel_acpi_scan() - SoundWire Intel init routine
153  * @parent_handle: ACPI parent handle
154  * @info: description of what firmware/DSDT tables expose
155  *
156  * This scans the namespace and queries firmware to figure out which
157  * links to enable. A follow-up use of sdw_intel_probe() and
158  * sdw_intel_startup() is required for creation of devices and bus
159  * startup
160  */
sdw_intel_acpi_scan(acpi_handle * parent_handle,struct sdw_intel_acpi_info * info)161 int sdw_intel_acpi_scan(acpi_handle *parent_handle,
162 			struct sdw_intel_acpi_info *info)
163 {
164 	acpi_status status;
165 
166 	info->handle = NULL;
167 	/*
168 	 * In the HDAS ACPI scope, 'SNDW' may be either the child of
169 	 * 'HDAS' or the grandchild of 'HDAS'. So let's go through
170 	 * the ACPI from 'HDAS' at max depth of 2 to find the 'SNDW'
171 	 * device.
172 	 */
173 	status = acpi_walk_namespace(ACPI_TYPE_DEVICE,
174 				     parent_handle, 2,
175 				     sdw_intel_acpi_cb,
176 				     NULL, info, NULL);
177 	if (ACPI_FAILURE(status) || info->handle == NULL)
178 		return -ENODEV;
179 
180 	return sdw_intel_scan_controller(info);
181 }
182 EXPORT_SYMBOL_NS(sdw_intel_acpi_scan, SND_INTEL_SOUNDWIRE_ACPI);
183 
184 MODULE_LICENSE("Dual BSD/GPL");
185 MODULE_DESCRIPTION("Intel Soundwire ACPI helpers");
186