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 ulong ctrl_addr = 0x40000000;
27module_param_named(sdw_ctrl_addr, ctrl_addr, ulong, 0444);
28MODULE_PARM_DESC(sdw_ctrl_addr, "Intel SoundWire Controller _ADR");
29
30static bool is_link_enabled(struct fwnode_handle *fw_node, u8 idx)
31{
32	struct fwnode_handle *link;
33	char name[32];
34	u32 quirk_mask = 0;
35
36	/* Find master handle */
37	snprintf(name, sizeof(name),
38		 "mipi-sdw-link-%hhu-subproperties", idx);
39
40	link = fwnode_get_named_child_node(fw_node, name);
41	if (!link)
42		return false;
43
44	fwnode_property_read_u32(link,
45				 "intel-quirk-mask",
46				 &quirk_mask);
47
48	if (quirk_mask & SDW_INTEL_QUIRK_MASK_BUS_DISABLE)
49		return false;
50
51	return true;
52}
53
54static int
55sdw_intel_scan_controller(struct sdw_intel_acpi_info *info)
56{
57	struct acpi_device *adev = acpi_fetch_acpi_dev(info->handle);
58	u8 count, i;
59	int ret;
60
61	if (!adev)
62		return -EINVAL;
63
64	/* Found controller, find links supported */
65	count = 0;
66	ret = fwnode_property_read_u8_array(acpi_fwnode_handle(adev),
67					    "mipi-sdw-master-count", &count, 1);
68
69	/*
70	 * In theory we could check the number of links supported in
71	 * hardware, but in that step we cannot assume SoundWire IP is
72	 * powered.
73	 *
74	 * In addition, if the BIOS doesn't even provide this
75	 * 'master-count' property then all the inits based on link
76	 * masks will fail as well.
77	 *
78	 * We will check the hardware capabilities in the startup() step
79	 */
80
81	if (ret) {
82		dev_err(&adev->dev,
83			"Failed to read mipi-sdw-master-count: %d\n", ret);
84		return -EINVAL;
85	}
86
87	/* Check count is within bounds */
88	if (count > SDW_MAX_LINKS) {
89		dev_err(&adev->dev, "Link count %d exceeds max %d\n",
90			count, SDW_MAX_LINKS);
91		return -EINVAL;
92	}
93
94	if (!count) {
95		dev_warn(&adev->dev, "No SoundWire links detected\n");
96		return -EINVAL;
97	}
98	dev_dbg(&adev->dev, "ACPI reports %d SDW Link devices\n", count);
99
100	info->count = count;
101	info->link_mask = 0;
102
103	for (i = 0; i < count; i++) {
104		if (ctrl_link_mask && !(ctrl_link_mask & BIT(i))) {
105			dev_dbg(&adev->dev,
106				"Link %d masked, will not be enabled\n", i);
107			continue;
108		}
109
110		if (!is_link_enabled(acpi_fwnode_handle(adev), i)) {
111			dev_dbg(&adev->dev,
112				"Link %d not selected in firmware\n", i);
113			continue;
114		}
115
116		info->link_mask |= BIT(i);
117	}
118
119	return 0;
120}
121
122static acpi_status sdw_intel_acpi_cb(acpi_handle handle, u32 level,
123				     void *cdata, void **return_value)
124{
125	struct sdw_intel_acpi_info *info = cdata;
126	acpi_status status;
127	u64 adr;
128
129	status = acpi_evaluate_integer(handle, METHOD_NAME__ADR, NULL, &adr);
130	if (ACPI_FAILURE(status))
131		return AE_OK; /* keep going */
132
133	if (!acpi_fetch_acpi_dev(handle)) {
134		pr_err("%s: Couldn't find ACPI handle\n", __func__);
135		return AE_NOT_FOUND;
136	}
137
138	/*
139	 * On some Intel platforms, multiple children of the HDAS
140	 * device can be found, but only one of them is the SoundWire
141	 * controller. The SNDW device is always exposed with
142	 * Name(_ADR, 0x40000000), with bits 31..28 representing the
143	 * SoundWire link so filter accordingly
144	 */
145	if (FIELD_GET(GENMASK(31, 28), adr) != SDW_LINK_TYPE)
146		return AE_OK; /* keep going */
147
148	if (adr != ctrl_addr)
149		return AE_OK; /* keep going */
150
151	/* found the correct SoundWire controller */
152	info->handle = handle;
153
154	/* device found, stop namespace walk */
155	return AE_CTRL_TERMINATE;
156}
157
158/**
159 * sdw_intel_acpi_scan() - SoundWire Intel init routine
160 * @parent_handle: ACPI parent handle
161 * @info: description of what firmware/DSDT tables expose
162 *
163 * This scans the namespace and queries firmware to figure out which
164 * links to enable. A follow-up use of sdw_intel_probe() and
165 * sdw_intel_startup() is required for creation of devices and bus
166 * startup
167 */
168int sdw_intel_acpi_scan(acpi_handle *parent_handle,
169			struct sdw_intel_acpi_info *info)
170{
171	acpi_status status;
172
173	info->handle = NULL;
174	/*
175	 * In the HDAS ACPI scope, 'SNDW' may be either the child of
176	 * 'HDAS' or the grandchild of 'HDAS'. So let's go through
177	 * the ACPI from 'HDAS' at max depth of 2 to find the 'SNDW'
178	 * device.
179	 */
180	status = acpi_walk_namespace(ACPI_TYPE_DEVICE,
181				     parent_handle, 2,
182				     sdw_intel_acpi_cb,
183				     NULL, info, NULL);
184	if (ACPI_FAILURE(status) || info->handle == NULL)
185		return -ENODEV;
186
187	return sdw_intel_scan_controller(info);
188}
189EXPORT_SYMBOL_NS(sdw_intel_acpi_scan, SND_INTEL_SOUNDWIRE_ACPI);
190
191MODULE_LICENSE("Dual BSD/GPL");
192MODULE_DESCRIPTION("Intel Soundwire ACPI helpers");
193