summaryrefslogtreecommitdiffstats
path: root/drivers/firmware/efi/dev-path-parser.c
diff options
context:
space:
mode:
authorLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2026-08-23 13:28:57 -0700
commit4352b8aee98005853aa63f57d6377282de17a33f (patch)
tree27614d7a9ef05c32d089004e104364ce42324837 /drivers/firmware/efi/dev-path-parser.c
downloadlinux-stable-4352b8aee98005853aa63f57d6377282de17a33f.tar.gz
linux-stable-4352b8aee98005853aa63f57d6377282de17a33f.zip
Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted
Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ...
Diffstat (limited to 'drivers/firmware/efi/dev-path-parser.c')
-rw-r--r--drivers/firmware/efi/dev-path-parser.c181
1 files changed, 181 insertions, 0 deletions
diff --git a/drivers/firmware/efi/dev-path-parser.c b/drivers/firmware/efi/dev-path-parser.c
new file mode 100644
index 000000000..13ea141c0
--- /dev/null
+++ b/drivers/firmware/efi/dev-path-parser.c
@@ -0,0 +1,181 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * dev-path-parser.c - EFI Device Path parser
+ * Copyright (C) 2016 Lukas Wunner <lukas@wunner.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License (version 2) as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/acpi.h>
+#include <linux/efi.h>
+#include <linux/pci.h>
+
+static long __init parse_acpi_path(const struct efi_dev_path *node,
+ struct device *parent, struct device **child)
+{
+ struct acpi_device *adev;
+ struct device *phys_dev;
+ char hid[ACPI_ID_LEN];
+
+ if (node->header.length != 12)
+ return -EINVAL;
+
+ sprintf(hid, "%c%c%c%04X",
+ 'A' + ((node->acpi.hid >> 10) & 0x1f) - 1,
+ 'A' + ((node->acpi.hid >> 5) & 0x1f) - 1,
+ 'A' + ((node->acpi.hid >> 0) & 0x1f) - 1,
+ node->acpi.hid >> 16);
+
+ for_each_acpi_dev_match(adev, hid, NULL, -1) {
+ if (acpi_dev_uid_match(adev, node->acpi.uid))
+ break;
+ if (!acpi_device_uid(adev) && node->acpi.uid == 0)
+ break;
+ }
+ if (!adev)
+ return -ENODEV;
+
+ phys_dev = acpi_get_first_physical_node(adev);
+ if (phys_dev) {
+ *child = get_device(phys_dev);
+ acpi_dev_put(adev);
+ } else
+ *child = &adev->dev;
+
+ return 0;
+}
+
+static int __init match_pci_dev(struct device *dev, const void *data)
+{
+ unsigned int devfn = *(const unsigned int *)data;
+
+ return dev_is_pci(dev) && to_pci_dev(dev)->devfn == devfn;
+}
+
+static long __init parse_pci_path(const struct efi_dev_path *node,
+ struct device *parent, struct device **child)
+{
+ unsigned int devfn;
+
+ if (node->header.length != 6)
+ return -EINVAL;
+ if (!parent)
+ return -EINVAL;
+
+ devfn = PCI_DEVFN(node->pci.dev, node->pci.fn);
+
+ *child = device_find_child(parent, &devfn, match_pci_dev);
+ if (!*child)
+ return -ENODEV;
+
+ return 0;
+}
+
+/*
+ * Insert parsers for further node types here.
+ *
+ * Each parser takes a pointer to the @node and to the @parent (will be NULL
+ * for the first device path node). If a device corresponding to @node was
+ * found below @parent, its reference count should be incremented and the
+ * device returned in @child.
+ *
+ * The return value should be 0 on success or a negative int on failure.
+ * The special return values 0x01 (EFI_DEV_END_INSTANCE) and 0xFF
+ * (EFI_DEV_END_ENTIRE) signal the end of the device path, only
+ * parse_end_path() is supposed to return this.
+ *
+ * Be sure to validate the node length and contents before commencing the
+ * search for a device.
+ */
+
+static long __init parse_end_path(const struct efi_dev_path *node,
+ struct device *parent, struct device **child)
+{
+ if (node->header.length != 4)
+ return -EINVAL;
+ if (node->header.sub_type != EFI_DEV_END_INSTANCE &&
+ node->header.sub_type != EFI_DEV_END_ENTIRE)
+ return -EINVAL;
+ if (!parent)
+ return -ENODEV;
+
+ *child = get_device(parent);
+ return node->header.sub_type;
+}
+
+/**
+ * efi_get_device_by_path - find device by EFI Device Path
+ * @node: EFI Device Path
+ * @len: maximum length of EFI Device Path in bytes
+ *
+ * Parse a series of EFI Device Path nodes at @node and find the corresponding
+ * device. If the device was found, its reference count is incremented and a
+ * pointer to it is returned. The caller needs to drop the reference with
+ * put_device() after use. The @node pointer is updated to point to the
+ * location immediately after the "End of Hardware Device Path" node.
+ *
+ * If another Device Path instance follows, @len is decremented by the number
+ * of bytes consumed. Otherwise @len is set to %0.
+ *
+ * If a Device Path node is malformed or its corresponding device is not found,
+ * @node is updated to point to this offending node and an ERR_PTR is returned.
+ *
+ * If @len is initially %0, the function returns %NULL. Thus, to iterate over
+ * all instances in a path, the following idiom may be used:
+ *
+ * while (!IS_ERR_OR_NULL(dev = efi_get_device_by_path(&node, &len))) {
+ * // do something with dev
+ * put_device(dev);
+ * }
+ * if (IS_ERR(dev))
+ * // report error
+ *
+ * Devices can only be found if they're already instantiated. Most buses
+ * instantiate devices in the "subsys" initcall level, hence the earliest
+ * initcall level in which this function should be called is "fs".
+ *
+ * Returns the device on success or
+ * %ERR_PTR(-ENODEV) if no device was found,
+ * %ERR_PTR(-EINVAL) if a node is malformed or exceeds @len,
+ * %ERR_PTR(-ENOTSUPP) if support for a node type is not yet implemented.
+ */
+struct device * __init efi_get_device_by_path(const struct efi_dev_path **node,
+ size_t *len)
+{
+ struct device *parent = NULL, *child;
+ long ret = 0;
+
+ if (!*len)
+ return NULL;
+
+ while (!ret) {
+ if (*len < 4 || *len < (*node)->header.length)
+ ret = -EINVAL;
+ else if ((*node)->header.type == EFI_DEV_ACPI &&
+ (*node)->header.sub_type == EFI_DEV_BASIC_ACPI)
+ ret = parse_acpi_path(*node, parent, &child);
+ else if ((*node)->header.type == EFI_DEV_HW &&
+ (*node)->header.sub_type == EFI_DEV_PCI)
+ ret = parse_pci_path(*node, parent, &child);
+ else if (((*node)->header.type == EFI_DEV_END_PATH ||
+ (*node)->header.type == EFI_DEV_END_PATH2))
+ ret = parse_end_path(*node, parent, &child);
+ else
+ ret = -ENOTSUPP;
+
+ put_device(parent);
+ if (ret < 0)
+ return ERR_PTR(ret);
+
+ parent = child;
+ *node = (void *)*node + (*node)->header.length;
+ *len -= (*node)->header.length;
+ }
+
+ if (ret == EFI_DEV_END_ENTIRE)
+ *len = 0;
+
+ return child;
+}