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 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 if (quirk_mask & SDW_INTEL_QUIRK_MASK_BUS_DISABLE) 45 return false; 46 47 return true; 48 } 49 50 static int 51 sdw_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 } 117 118 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 */ 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