Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 731 insertions, 0 deletions

diff --git a/drivers/thunderbolt/eeprom.c b/drivers/thunderbolt/eeprom.c
new file mode 100644
index 000000000..2a13fa688
--- /dev/null
+++ b/drivers/thunderbolt/eeprom.c
@@ -0,0 +1,731 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Thunderbolt driver - eeprom access
+ *
+ * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
+ * Copyright (C) 2018, Intel Corporation
+ */
+
+#include <linux/crc32.h>
+#include <linux/delay.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+#include "tb.h"
+
+/*
+ * tb_eeprom_ctl_write() - write control word
+ */
+static int tb_eeprom_ctl_write(struct tb_switch *sw, struct tb_eeprom_ctl *ctl)
+{
+	return tb_sw_write(sw, ctl, TB_CFG_SWITCH, sw->cap_plug_events + ROUTER_CS_4, 1);
+}
+
+/*
+ * tb_eeprom_ctl_read() - read control word
+ */
+static int tb_eeprom_ctl_read(struct tb_switch *sw, struct tb_eeprom_ctl *ctl)
+{
+	return tb_sw_read(sw, ctl, TB_CFG_SWITCH, sw->cap_plug_events + ROUTER_CS_4, 1);
+}
+
+enum tb_eeprom_transfer {
+	TB_EEPROM_IN,
+	TB_EEPROM_OUT,
+};
+
+/*
+ * tb_eeprom_active - enable rom access
+ *
+ * WARNING: Always disable access after usage. Otherwise the controller will
+ * fail to reprobe.
+ */
+static int tb_eeprom_active(struct tb_switch *sw, bool enable)
+{
+	struct tb_eeprom_ctl ctl;
+	int res = tb_eeprom_ctl_read(sw, &ctl);
+	if (res)
+		return res;
+	if (enable) {
+		ctl.bit_banging_enable = 1;
+		res = tb_eeprom_ctl_write(sw, &ctl);
+		if (res)
+			return res;
+		ctl.fl_cs = 0;
+		return tb_eeprom_ctl_write(sw, &ctl);
+	} else {
+		ctl.fl_cs = 1;
+		res = tb_eeprom_ctl_write(sw, &ctl);
+		if (res)
+			return res;
+		ctl.bit_banging_enable = 0;
+		return tb_eeprom_ctl_write(sw, &ctl);
+	}
+}
+
+/*
+ * tb_eeprom_transfer - transfer one bit
+ *
+ * If TB_EEPROM_IN is passed, then the bit can be retrieved from ctl->fl_do.
+ * If TB_EEPROM_OUT is passed, then ctl->fl_di will be written.
+ */
+static int tb_eeprom_transfer(struct tb_switch *sw, struct tb_eeprom_ctl *ctl,
+			      enum tb_eeprom_transfer direction)
+{
+	int res;
+	if (direction == TB_EEPROM_OUT) {
+		res = tb_eeprom_ctl_write(sw, ctl);
+		if (res)
+			return res;
+	}
+	ctl->fl_sk = 1;
+	res = tb_eeprom_ctl_write(sw, ctl);
+	if (res)
+		return res;
+	if (direction == TB_EEPROM_IN) {
+		res = tb_eeprom_ctl_read(sw, ctl);
+		if (res)
+			return res;
+	}
+	ctl->fl_sk = 0;
+	return tb_eeprom_ctl_write(sw, ctl);
+}
+
+/*
+ * tb_eeprom_out - write one byte to the bus
+ */
+static int tb_eeprom_out(struct tb_switch *sw, u8 val)
+{
+	struct tb_eeprom_ctl ctl;
+	int i;
+	int res = tb_eeprom_ctl_read(sw, &ctl);
+	if (res)
+		return res;
+	for (i = 0; i < 8; i++) {
+		ctl.fl_di = val & 0x80;
+		res = tb_eeprom_transfer(sw, &ctl, TB_EEPROM_OUT);
+		if (res)
+			return res;
+		val <<= 1;
+	}
+	return 0;
+}
+
+/*
+ * tb_eeprom_in - read one byte from the bus
+ */
+static int tb_eeprom_in(struct tb_switch *sw, u8 *val)
+{
+	struct tb_eeprom_ctl ctl;
+	int i;
+	int res = tb_eeprom_ctl_read(sw, &ctl);
+	if (res)
+		return res;
+	*val = 0;
+	for (i = 0; i < 8; i++) {
+		*val <<= 1;
+		res = tb_eeprom_transfer(sw, &ctl, TB_EEPROM_IN);
+		if (res)
+			return res;
+		*val |= ctl.fl_do;
+	}
+	return 0;
+}
+
+/*
+ * tb_eeprom_get_drom_offset - get drom offset within eeprom
+ */
+static int tb_eeprom_get_drom_offset(struct tb_switch *sw, u16 *offset)
+{
+	struct tb_cap_plug_events cap;
+	int res;
+
+	if (!sw->cap_plug_events) {
+		tb_sw_warn(sw, "no TB_CAP_PLUG_EVENTS, cannot read eeprom\n");
+		return -ENODEV;
+	}
+	res = tb_sw_read(sw, &cap, TB_CFG_SWITCH, sw->cap_plug_events,
+			     sizeof(cap) / 4);
+	if (res)
+		return res;
+
+	if (!cap.eeprom_ctl.present || cap.eeprom_ctl.not_present) {
+		tb_sw_warn(sw, "no NVM\n");
+		return -ENODEV;
+	}
+
+	if (cap.drom_offset > 0xffff) {
+		tb_sw_warn(sw, "drom offset is larger than 0xffff: %#x\n",
+				cap.drom_offset);
+		return -ENXIO;
+	}
+	*offset = cap.drom_offset;
+	return 0;
+}
+
+/*
+ * tb_eeprom_read_n - read count bytes from offset into val
+ */
+static int tb_eeprom_read_n(struct tb_switch *sw, u16 offset, u8 *val,
+		size_t count)
+{
+	u16 drom_offset;
+	int i, res;
+
+	res = tb_eeprom_get_drom_offset(sw, &drom_offset);
+	if (res)
+		return res;
+
+	offset += drom_offset;
+
+	res = tb_eeprom_active(sw, true);
+	if (res)
+		return res;
+	res = tb_eeprom_out(sw, 3);
+	if (res)
+		return res;
+	res = tb_eeprom_out(sw, offset >> 8);
+	if (res)
+		return res;
+	res = tb_eeprom_out(sw, offset);
+	if (res)
+		return res;
+	for (i = 0; i < count; i++) {
+		res = tb_eeprom_in(sw, val + i);
+		if (res)
+			return res;
+	}
+	return tb_eeprom_active(sw, false);
+}
+
+static u8 tb_crc8(u8 *data, int len)
+{
+	int i, j;
+	u8 val = 0xff;
+	for (i = 0; i < len; i++) {
+		val ^= data[i];
+		for (j = 0; j < 8; j++)
+			val = (val << 1) ^ ((val & 0x80) ? 7 : 0);
+	}
+	return val;
+}
+
+static u32 tb_crc32(void *data, size_t len)
+{
+	return ~crc32c(~0, data, len);
+}
+
+#define TB_DROM_DATA_START		13
+#define TB_DROM_HEADER_SIZE		22
+#define USB4_DROM_HEADER_SIZE		16
+
+struct tb_drom_header {
+	/* BYTE 0 */
+	u8 uid_crc8; /* checksum for uid */
+	/* BYTES 1-8 */
+	u64 uid;
+	/* BYTES 9-12 */
+	u32 data_crc32; /* checksum for data_len bytes starting at byte 13 */
+	/* BYTE 13 */
+	u8 device_rom_revision; /* should be <= 1 */
+	u16 data_len:12;
+	u8 reserved:4;
+	/* BYTES 16-21 - Only for TBT DROM, nonexistent in USB4 DROM */
+	u16 vendor_id;
+	u16 model_id;
+	u8 model_rev;
+	u8 eeprom_rev;
+} __packed;
+
+enum tb_drom_entry_type {
+	/* force unsigned to prevent "one-bit signed bitfield" warning */
+	TB_DROM_ENTRY_GENERIC = 0U,
+	TB_DROM_ENTRY_PORT,
+};
+
+struct tb_drom_entry_header {
+	u8 len;
+	u8 index:6;
+	bool port_disabled:1; /* only valid if type is TB_DROM_ENTRY_PORT */
+	enum tb_drom_entry_type type:1;
+} __packed;
+
+struct tb_drom_entry_generic {
+	struct tb_drom_entry_header header;
+	u8 data[];
+} __packed;
+
+struct tb_drom_entry_port {
+	/* BYTES 0-1 */
+	struct tb_drom_entry_header header;
+	/* BYTE 2 */
+	u8 dual_link_port_rid:4;
+	u8 link_nr:1;
+	u8 unknown1:2;
+	bool has_dual_link_port:1;
+
+	/* BYTE 3 */
+	u8 dual_link_port_nr:6;
+	u8 unknown2:2;
+
+	/* BYTES 4 - 5 TODO decode */
+	u8 micro2:4;
+	u8 micro1:4;
+	u8 micro3;
+
+	/* BYTES 6-7, TODO: verify (find hardware that has these set) */
+	u8 peer_port_rid:4;
+	u8 unknown3:3;
+	bool has_peer_port:1;
+	u8 peer_port_nr:6;
+	u8 unknown4:2;
+} __packed;
+
+/* USB4 product descriptor */
+struct tb_drom_entry_desc {
+	struct tb_drom_entry_header header;
+	u16 bcdUSBSpec;
+	u16 idVendor;
+	u16 idProduct;
+	u16 bcdProductFWRevision;
+	u32 TID;
+	u8 productHWRevision;
+};
+
+/**
+ * tb_drom_read_uid_only() - Read UID directly from DROM
+ * @sw: Router whose UID to read
+ * @uid: UID is placed here
+ *
+ * Does not use the cached copy in sw->drom. Used during resume to check switch
+ * identity.
+ *
+ * Return: %0 on success, negative errno otherwise.
+ */
+int tb_drom_read_uid_only(struct tb_switch *sw, u64 *uid)
+{
+	u8 data[9];
+	u8 crc;
+	int res;
+
+	/* read uid */
+	res = tb_eeprom_read_n(sw, 0, data, 9);
+	if (res)
+		return res;
+
+	crc = tb_crc8(data + 1, 8);
+	if (crc != data[0]) {
+		tb_sw_warn(sw, "uid crc8 mismatch (expected: %#x, got: %#x)\n",
+				data[0], crc);
+		return -EIO;
+	}
+
+	*uid = *(u64 *)(data+1);
+	return 0;
+}
+
+static int tb_drom_parse_entry_generic(struct tb_switch *sw,
+		struct tb_drom_entry_header *header)
+{
+	const struct tb_drom_entry_generic *entry =
+		(const struct tb_drom_entry_generic *)header;
+
+	switch (header->index) {
+	case 1:
+		/* Length includes 2 bytes header so remove it before copy */
+		sw->vendor_name = kstrndup(entry->data,
+			header->len - sizeof(*header), GFP_KERNEL);
+		if (!sw->vendor_name)
+			return -ENOMEM;
+		break;
+
+	case 2:
+		sw->device_name = kstrndup(entry->data,
+			header->len - sizeof(*header), GFP_KERNEL);
+		if (!sw->device_name)
+			return -ENOMEM;
+		break;
+	case 9: {
+		const struct tb_drom_entry_desc *desc =
+			(const struct tb_drom_entry_desc *)entry;
+
+		if (!sw->vendor && !sw->device) {
+			sw->vendor = desc->idVendor;
+			sw->device = desc->idProduct;
+		}
+		break;
+	}
+	}
+
+	return 0;
+}
+
+static int tb_drom_parse_entry_port(struct tb_switch *sw,
+				    struct tb_drom_entry_header *header)
+{
+	struct tb_port *port;
+	int res;
+	enum tb_port_type type;
+
+	/*
+	 * Some DROMs list more ports than the controller actually has
+	 * so we skip those but allow the parser to continue.
+	 */
+	if (header->index > sw->config.max_port_number) {
+		dev_info_once(&sw->dev, "ignoring unnecessary extra entries in DROM\n");
+		return 0;
+	}
+
+	port = &sw->ports[header->index];
+	port->disabled = header->port_disabled;
+	if (port->disabled)
+		return 0;
+
+	res = tb_port_read(port, &type, TB_CFG_PORT, 2, 1);
+	if (res)
+		return res;
+	type &= 0xffffff;
+
+	if (type == TB_TYPE_PORT) {
+		struct tb_drom_entry_port *entry = (void *) header;
+		if (header->len != sizeof(*entry)) {
+			tb_sw_warn(sw,
+				"port entry has size %#x (expected %#zx)\n",
+				header->len, sizeof(struct tb_drom_entry_port));
+			return -EIO;
+		}
+		port->link_nr = entry->link_nr;
+		if (entry->has_dual_link_port) {
+			if (entry->dual_link_port_nr > sw->config.max_port_number) {
+				tb_sw_warn(sw,
+					"port entry has invalid dual link port number %u\n",
+					entry->dual_link_port_nr);
+				return -EIO;
+			}
+			port->dual_link_port =
+				&port->sw->ports[entry->dual_link_port_nr];
+		}
+	}
+	return 0;
+}
+
+/*
+ * tb_drom_parse_entries - parse the linked list of drom entries
+ *
+ * Drom must have been copied to sw->drom.
+ */
+static int tb_drom_parse_entries(struct tb_switch *sw, size_t header_size)
+{
+	struct tb_drom_header *header = (void *) sw->drom;
+	u16 pos = header_size;
+	u16 drom_size = header->data_len + TB_DROM_DATA_START;
+	int res;
+
+	while (pos < drom_size) {
+		struct tb_drom_entry_header *entry = (void *) (sw->drom + pos);
+		if (pos + 1 == drom_size || pos + entry->len > drom_size
+				|| !entry->len) {
+			tb_sw_warn(sw, "DROM buffer overrun\n");
+			return -EIO;
+		}
+
+		switch (entry->type) {
+		case TB_DROM_ENTRY_GENERIC:
+			res = tb_drom_parse_entry_generic(sw, entry);
+			break;
+		case TB_DROM_ENTRY_PORT:
+			res = tb_drom_parse_entry_port(sw, entry);
+			break;
+		}
+		if (res)
+			return res;
+
+		pos += entry->len;
+	}
+	return 0;
+}
+
+static int tb_switch_drom_alloc(struct tb_switch *sw, size_t size)
+{
+	sw->drom = kzalloc(size, GFP_KERNEL);
+	if (!sw->drom)
+		return -ENOMEM;
+
+#ifdef CONFIG_DEBUG_FS
+	sw->drom_blob.data = sw->drom;
+	sw->drom_blob.size = size;
+#endif
+	return 0;
+}
+
+static void tb_switch_drom_free(struct tb_switch *sw)
+{
+#ifdef CONFIG_DEBUG_FS
+	sw->drom_blob.data = NULL;
+	sw->drom_blob.size = 0;
+#endif
+	kfree(sw->drom);
+	sw->drom = NULL;
+}
+
+/*
+ * tb_drom_copy_efi - copy drom supplied by EFI to sw->drom if present
+ */
+static int tb_drom_copy_efi(struct tb_switch *sw, u16 *size)
+{
+	struct device *dev = sw->tb->nhi->dev;
+	int len, res;
+
+	len = device_property_count_u8(dev, "ThunderboltDROM");
+	if (len < 0 || len < sizeof(struct tb_drom_header))
+		return -EINVAL;
+
+	res = tb_switch_drom_alloc(sw, len);
+	if (res)
+		return res;
+
+	res = device_property_read_u8_array(dev, "ThunderboltDROM", sw->drom,
+									len);
+	if (res)
+		goto err;
+
+	*size = ((struct tb_drom_header *)sw->drom)->data_len +
+							  TB_DROM_DATA_START;
+	if (*size > len)
+		goto err;
+
+	return 0;
+
+err:
+	tb_switch_drom_free(sw);
+	return -EINVAL;
+}
+
+static int tb_drom_copy_nvm(struct tb_switch *sw, u16 *size)
+{
+	u16 drom_offset;
+	int ret;
+
+	if (!sw->dma_port)
+		return -ENODEV;
+
+	ret = tb_eeprom_get_drom_offset(sw, &drom_offset);
+	if (ret)
+		return ret;
+
+	if (!drom_offset)
+		return -ENODEV;
+
+	ret = dma_port_flash_read(sw->dma_port, drom_offset + 14, size,
+				  sizeof(*size));
+	if (ret)
+		return ret;
+
+	/* Size includes CRC8 + UID + CRC32 */
+	*size += 1 + 8 + 4;
+	ret = tb_switch_drom_alloc(sw, *size);
+	if (ret)
+		return ret;
+
+	ret = dma_port_flash_read(sw->dma_port, drom_offset, sw->drom, *size);
+	if (ret) {
+		tb_switch_drom_free(sw);
+		return ret;
+	}
+
+	/*
+	 * Read UID from the minimal DROM because the one in NVM is just
+	 * a placeholder.
+	 */
+	tb_drom_read_uid_only(sw, &sw->uid);
+	return 0;
+}
+
+static int usb4_copy_drom(struct tb_switch *sw, u16 *size)
+{
+	int ret;
+
+	ret = usb4_switch_drom_read(sw, 14, size, sizeof(*size));
+	if (ret)
+		return ret;
+
+	/* Size includes CRC8 + UID + CRC32 */
+	*size += 1 + 8 + 4;
+	ret = tb_switch_drom_alloc(sw, *size);
+	if (ret)
+		return ret;
+
+	ret = usb4_switch_drom_read(sw, 0, sw->drom, *size);
+	if (ret)
+		tb_switch_drom_free(sw);
+
+	return ret;
+}
+
+static int tb_drom_bit_bang(struct tb_switch *sw, u16 *size)
+{
+	int ret;
+
+	ret = tb_eeprom_read_n(sw, 14, (u8 *)size, 2);
+	if (ret)
+		return ret;
+
+	*size &= 0x3ff;
+	*size += TB_DROM_DATA_START;
+
+	tb_sw_dbg(sw, "reading DROM (length: %#x)\n", *size);
+	if (*size < sizeof(struct tb_drom_header)) {
+		tb_sw_warn(sw, "DROM too small, aborting\n");
+		return -EIO;
+	}
+
+	ret = tb_switch_drom_alloc(sw, *size);
+	if (ret)
+		return ret;
+
+	ret = tb_eeprom_read_n(sw, 0, sw->drom, *size);
+	if (ret)
+		tb_switch_drom_free(sw);
+
+	return ret;
+}
+
+static int tb_drom_parse_v1(struct tb_switch *sw)
+{
+	const struct tb_drom_header *header =
+		(const struct tb_drom_header *)sw->drom;
+	u32 crc;
+
+	crc = tb_crc8((u8 *) &header->uid, 8);
+	if (crc != header->uid_crc8) {
+		tb_sw_warn(sw,
+			"DROM UID CRC8 mismatch (expected: %#x, got: %#x)\n",
+			header->uid_crc8, crc);
+		return -EIO;
+	}
+	if (!sw->uid)
+		sw->uid = header->uid;
+	sw->vendor = header->vendor_id;
+	sw->device = header->model_id;
+
+	crc = tb_crc32(sw->drom + TB_DROM_DATA_START, header->data_len);
+	if (crc != header->data_crc32) {
+		tb_sw_warn(sw,
+			"DROM data CRC32 mismatch (expected: %#x, got: %#x), continuing\n",
+			header->data_crc32, crc);
+	}
+
+	return tb_drom_parse_entries(sw, TB_DROM_HEADER_SIZE);
+}
+
+static int usb4_drom_parse(struct tb_switch *sw)
+{
+	const struct tb_drom_header *header =
+		(const struct tb_drom_header *)sw->drom;
+	u32 crc;
+
+	crc = tb_crc32(sw->drom + TB_DROM_DATA_START, header->data_len);
+	if (crc != header->data_crc32) {
+		tb_sw_warn(sw,
+			   "DROM data CRC32 mismatch (expected: %#x, got: %#x), continuing\n",
+			   header->data_crc32, crc);
+	}
+
+	return tb_drom_parse_entries(sw, USB4_DROM_HEADER_SIZE);
+}
+
+static int tb_drom_parse(struct tb_switch *sw, u16 size)
+{
+	const struct tb_drom_header *header = (const void *)sw->drom;
+	int ret;
+
+	if (header->data_len + TB_DROM_DATA_START != size) {
+		tb_sw_warn(sw, "DROM size mismatch\n");
+		ret = -EIO;
+		goto err;
+	}
+
+	tb_sw_dbg(sw, "DROM version: %d\n", header->device_rom_revision);
+
+	switch (header->device_rom_revision) {
+	case 3:
+		ret = usb4_drom_parse(sw);
+		break;
+	default:
+		tb_sw_warn(sw, "DROM device_rom_revision %#x unknown\n",
+			   header->device_rom_revision);
+		fallthrough;
+	case 1:
+		ret = tb_drom_parse_v1(sw);
+		break;
+	}
+
+	if (ret) {
+		tb_sw_warn(sw, "parsing DROM failed\n");
+		goto err;
+	}
+
+	return 0;
+
+err:
+	tb_switch_drom_free(sw);
+	return ret;
+}
+
+static int tb_drom_host_read(struct tb_switch *sw)
+{
+	u16 size;
+
+	if (tb_switch_is_usb4(sw)) {
+		usb4_switch_read_uid(sw, &sw->uid);
+		if (!usb4_copy_drom(sw, &size))
+			return tb_drom_parse(sw, size);
+	} else {
+		if (!tb_drom_copy_efi(sw, &size))
+			return tb_drom_parse(sw, size);
+
+		if (!tb_drom_copy_nvm(sw, &size))
+			return tb_drom_parse(sw, size);
+
+		tb_drom_read_uid_only(sw, &sw->uid);
+	}
+
+	return 0;
+}
+
+static int tb_drom_device_read(struct tb_switch *sw)
+{
+	u16 size;
+	int ret;
+
+	if (tb_switch_is_usb4(sw)) {
+		usb4_switch_read_uid(sw, &sw->uid);
+		ret = usb4_copy_drom(sw, &size);
+	} else {
+		ret = tb_drom_bit_bang(sw, &size);
+	}
+
+	if (ret)
+		return ret;
+
+	return tb_drom_parse(sw, size);
+}
+
+/**
+ * tb_drom_read() - Copy DROM to sw->drom and parse it
+ * @sw: Router whose DROM to read and parse
+ *
+ * This function reads router DROM and if successful parses the entries and
+ * populates the fields in @sw accordingly. Can be called for any router
+ * generation.
+ *
+ * Return: %0 on success, negative errno otherwise.
+ */
+int tb_drom_read(struct tb_switch *sw)
+{
+	if (sw->drom)
+		return 0;
+
+	if (!tb_route(sw))
+		return tb_drom_host_read(sw);
+	return tb_drom_device_read(sw);
+}