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	fwnode_handle_put(link);
 49
 50	if (quirk_mask & SDW_INTEL_QUIRK_MASK_BUS_DISABLE)
 51		return false;
 52
 53	return true;
 54}
 55
 56static int
 57sdw_intel_scan_controller(struct sdw_intel_acpi_info *info)
 58{
 59	struct acpi_device *adev = acpi_fetch_acpi_dev(info->handle);
 60	u8 count, i;
 61	int ret;
 62
 63	if (!adev)
 64		return -EINVAL;
 65
 66	/* Found controller, find links supported */
 67	count = 0;
 68	ret = fwnode_property_read_u8_array(acpi_fwnode_handle(adev),
 69					    "mipi-sdw-master-count", &count, 1);
 70
 71	/*
 72	 * In theory we could check the number of links supported in
 73	 * hardware, but in that step we cannot assume SoundWire IP is
 74	 * powered.
 75	 *
 76	 * In addition, if the BIOS doesn't even provide this
 77	 * 'master-count' property then all the inits based on link
 78	 * masks will fail as well.
 79	 *
 80	 * We will check the hardware capabilities in the startup() step
 81	 */
 82
 83	if (ret) {
 84		dev_err(&adev->dev,
 85			"Failed to read mipi-sdw-master-count: %d\n", ret);
 86		return -EINVAL;
 87	}
 88
 89	/* Check count is within bounds */
 90	if (count > SDW_MAX_LINKS) {
 91		dev_err(&adev->dev, "Link count %d exceeds max %d\n",
 92			count, SDW_MAX_LINKS);
 93		return -EINVAL;
 94	}
 95
 96	if (!count) {
 97		dev_warn(&adev->dev, "No SoundWire links detected\n");
 98		return -EINVAL;
 99	}
100	dev_dbg(&adev->dev, "ACPI reports %d SDW Link devices\n", count);
101
102	info->count = count;
103	info->link_mask = 0;
104
105	for (i = 0; i < count; i++) {
106		if (ctrl_link_mask && !(ctrl_link_mask & BIT(i))) {
107			dev_dbg(&adev->dev,
108				"Link %d masked, will not be enabled\n", i);
109			continue;
110		}
111
112		if (!is_link_enabled(acpi_fwnode_handle(adev), i)) {
113			dev_dbg(&adev->dev,
114				"Link %d not selected in firmware\n", i);
115			continue;
116		}
117
118		info->link_mask |= BIT(i);
119	}
120
121	return 0;
122}
123
124static acpi_status sdw_intel_acpi_cb(acpi_handle handle, u32 level,
125				     void *cdata, void **return_value)
126{
127	struct sdw_intel_acpi_info *info = cdata;
128	acpi_status status;
129	u64 adr;
130
131	status = acpi_evaluate_integer(handle, METHOD_NAME__ADR, NULL, &adr);
132	if (ACPI_FAILURE(status))
133		return AE_OK; /* keep going */
134
135	if (!acpi_fetch_acpi_dev(handle)) {
136		pr_err("%s: Couldn't find ACPI handle\n", __func__);
137		return AE_NOT_FOUND;
138	}
139
140	/*
141	 * On some Intel platforms, multiple children of the HDAS
142	 * device can be found, but only one of them is the SoundWire
143	 * controller. The SNDW device is always exposed with
144	 * Name(_ADR, 0x40000000), with bits 31..28 representing the
145	 * SoundWire link so filter accordingly
146	 */
147	if (FIELD_GET(GENMASK(31, 28), adr) != SDW_LINK_TYPE)
148		return AE_OK; /* keep going */
149
150	if (adr != ctrl_addr)
151		return AE_OK; /* keep going */
152
153	/* found the correct SoundWire controller */
154	info->handle = handle;
155
156	/* device found, stop namespace walk */
157	return AE_CTRL_TERMINATE;
158}
159
160/**
161 * sdw_intel_acpi_scan() - SoundWire Intel init routine
162 * @parent_handle: ACPI parent handle
163 * @info: description of what firmware/DSDT tables expose
164 *
165 * This scans the namespace and queries firmware to figure out which
166 * links to enable. A follow-up use of sdw_intel_probe() and
167 * sdw_intel_startup() is required for creation of devices and bus
168 * startup
169 */
170int sdw_intel_acpi_scan(acpi_handle *parent_handle,
171			struct sdw_intel_acpi_info *info)
172{
173	acpi_status status;
174
175	info->handle = NULL;
176	/*
177	 * In the HDAS ACPI scope, 'SNDW' may be either the child of
178	 * 'HDAS' or the grandchild of 'HDAS'. So let's go through
179	 * the ACPI from 'HDAS' at max depth of 2 to find the 'SNDW'
180	 * device.
181	 */
182	status = acpi_walk_namespace(ACPI_TYPE_DEVICE,
183				     parent_handle, 2,
184				     sdw_intel_acpi_cb,
185				     NULL, info, NULL);
186	if (ACPI_FAILURE(status) || info->handle == NULL)
187		return -ENODEV;
188
189	return sdw_intel_scan_controller(info);
190}
191EXPORT_SYMBOL_NS(sdw_intel_acpi_scan, SND_INTEL_SOUNDWIRE_ACPI);
192
193MODULE_LICENSE("Dual BSD/GPL");
194MODULE_DESCRIPTION("Intel Soundwire ACPI helpers");