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
22static int ctrl_link_mask;
23module_param_named(sdw_link_mask, ctrl_link_mask, int, 0444);
24MODULE_PARM_DESC(sdw_link_mask, "Intel link mask (one bit per link)");
25
26static 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	if (quirk_mask & SDW_INTEL_QUIRK_MASK_BUS_DISABLE)
45		return false;
46
47	return true;
48}
49
50static int
51sdw_intel_scan_controller(struct sdw_intel_acpi_info *info)
52{
53	struct acpi_device *adev = acpi_fetch_acpi_dev(info->handle);
54	u8 count, i;
55	int ret;
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
118static 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 */
161int 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}
182EXPORT_SYMBOL_NS(sdw_intel_acpi_scan, SND_INTEL_SOUNDWIRE_ACPI);
183
184MODULE_LICENSE("Dual BSD/GPL");
185MODULE_DESCRIPTION("Intel Soundwire ACPI helpers");
186