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