[PATCH 1/2] thunderbolt: Read port configuration from eeprom.

[Andreas Noever]

All Thunderbolt switches (except the root switch) contain a drom which
contains information about the device. Right now we only read the UID.

Add code to read and parse this drom. For now we are only interested in
which ports are disabled and which ports are "dual link ports" (a
physical thunderbolt port/socket contains two such ports).

Signed-off-by: Andreas Noever <andreas.noever@xxxxxxxxx>
---
 drivers/thunderbolt/eeprom.c | 266 ++++++++++++++++++++++++++++++++++++++++++-
 drivers/thunderbolt/switch.c |   4 +-
 drivers/thunderbolt/tb.h     |   7 +-
 3 files changed, 270 insertions(+), 7 deletions(-)

diff --git a/drivers/thunderbolt/eeprom.c b/drivers/thunderbolt/eeprom.c
index f28e402..0d5a80b 100644
--- a/drivers/thunderbolt/eeprom.c
+++ b/drivers/thunderbolt/eeprom.c
@@ -4,6 +4,7 @@
  * Copyright (c) 2014 Andreas Noever <andreas.noever@xxxxxxxxx>
  */
 
+#include <linux/crc32.h>
 #include "tb.h"
 
 /**
@@ -152,9 +153,86 @@ static int tb_eeprom_read_n(struct tb_switch *sw, u16 offset, u8 *val,
 	return tb_eeprom_active(sw, false);
 }
 
-int tb_eeprom_read_uid(struct tb_switch *sw, u64 *uid)
+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_le(~0, data, len);
+}
+
+#define TB_DROM_DATA_START 13
+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:10;
+	u8 __unknown1:6;
+	/* BYTES 16-21 */
+	u16 vendor_id;
+	u16 model_id;
+	u8 model_rev;
+	u8 eeprom_rev;
+} __packed;
+
+enum tb_drom_entry_type {
+	TB_DROM_ENTRY_GENERIC,
+	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_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 5-6, 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;
+
+
+/**
+ * tb_eeprom_get_drom_offset - get drom offset within eeprom
+ */
+int tb_eeprom_get_drom_offset(struct tb_switch *sw, u16 *offset)
 {
-	u8 data[9];
 	struct tb_cap_plug_events cap;
 	int res;
 	if (!sw->cap_plug_events) {
@@ -165,6 +243,7 @@ int tb_eeprom_read_uid(struct tb_switch *sw, u64 *uid)
 			     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 -ENOSYS;
@@ -175,15 +254,194 @@ int tb_eeprom_read_uid(struct tb_switch *sw, u64 *uid)
 				cap.drom_offset);
 		return -ENXIO;
 	}
+	*offset = cap.drom_offset;
+	return 0;
+}
+
+/**
+ * tb_drom_read_uid_only - read uid directly from drom
+ *
+ * Does not use the cached copy in sw->drom. Used during resume to check switch
+ * identity.
+ */
+int tb_drom_read_uid_only(struct tb_switch *sw, u64 *uid)
+{
+	u8 data[9];
+	u16 drom_offset;
+	u8 crc;
+	int res = tb_eeprom_get_drom_offset(sw, &drom_offset);
+	if (res)
+		return res;
 
 	/* read uid */
-	res = tb_eeprom_read_n(sw, cap.drom_offset, data, 9);
+	res = tb_eeprom_read_n(sw, drom_offset, data, 9);
 	if (res)
 		return res;
-	/* TODO: check checksum in data[0] */
+
+	crc = tb_crc8(data + 1, 8);
+	if (crc != data[0]) {
+		tb_sw_warn(sw, "uid crc8 missmatch (expected: %#x, got: %#x)\n",
+				data[0], crc);
+		return -EIO;
+	}
+
 	*uid = *(u64 *)(data+1);
 	return 0;
 }
 
+static void tb_drom_parse_port_entry(struct tb_port *port,
+		struct tb_drom_entry_port *entry)
+{
+	port->link_nr = entry->link_nr;
+	if (entry->has_dual_link_port)
+		port->dual_link_port =
+				&port->sw->ports[entry->dual_link_port_nr];
+}
+
+static int tb_drom_parse_entry(struct tb_switch *sw,
+		struct tb_drom_entry_header *header)
+{
+	struct tb_port *port;
+	int res;
+	enum tb_port_type type;
 
+	if (header->type != TB_DROM_ENTRY_PORT)
+		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 %#lx)\n",
+				header->len, sizeof(struct tb_drom_entry_port));
+			return -EIO;
+		}
+		tb_drom_parse_port_entry(port, entry);
+	}
+	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)
+{
+	struct tb_drom_header *header = (void *) sw->drom;
+	u16 pos = sizeof(*header);
+	u16 drom_size = header->data_len + TB_DROM_DATA_START;
+
+	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, aborting\n");
+			return -EIO;
+		}
+
+		tb_drom_parse_entry(sw, entry);
+
+		pos += entry->len;
+	}
+	return 0;
+}
+
+/**
+ * tb_drom_read - copy drom to sw->drom and parse it
+ */
+int tb_drom_read(struct tb_switch *sw)
+{
+	u16 drom_offset;
+	u16 size;
+	u32 crc;
+	struct tb_drom_header *header;
+	int res;
+	if (sw->drom)
+		return 0;
+
+	if (tb_route(sw) == 0) {
+		/*
+		 * The root switch contains only a dummy drom (header only,
+		 * no entries). Hardcode the configuration here.
+		 */
+		tb_drom_read_uid_only(sw, &sw->uid);
+
+		sw->ports[1].link_nr = 0;
+		sw->ports[2].link_nr = 1;
+		sw->ports[1].dual_link_port = &sw->ports[2];
+		sw->ports[2].dual_link_port = &sw->ports[1];
+
+		sw->ports[3].link_nr = 0;
+		sw->ports[4].link_nr = 1;
+		sw->ports[3].dual_link_port = &sw->ports[4];
+		sw->ports[4].dual_link_port = &sw->ports[3];
+		return 0;
+	}
+
+	res = tb_eeprom_get_drom_offset(sw, &drom_offset);
+	if (res)
+		return res;
+
+	res = tb_eeprom_read_n(sw, drom_offset + 14, (u8 *) &size, 2);
+	if (res)
+		return res;
+	size &= 0x3ff;
+	size += TB_DROM_DATA_START;
+	tb_sw_info(sw, "reading drom (length: %#x)\n", size);
+	if (size < sizeof(*header)) {
+		tb_sw_warn(sw, "drom too small, aborting\n");
+		return -EIO;
+	}
+
+	sw->drom = kzalloc(size, GFP_KERNEL);
+	if (!sw->drom)
+		return -ENOMEM;
+	res = tb_eeprom_read_n(sw, drom_offset, sw->drom, size);
+	if (res)
+		goto err;
+
+	header = (void *) sw->drom;
+
+	if (header->data_len + TB_DROM_DATA_START != size) {
+		tb_sw_warn(sw, "drom size mismatch, aborting\n");
+		goto err;
+	}
+
+	crc = tb_crc8((u8 *) &header->uid, 8);
+	if (crc != header->uid_crc8) {
+		tb_sw_warn(sw,
+			"drom uid crc8 mismatch (expected: %#x, got: %#x), aborting\n",
+			header->uid_crc8, crc);
+		goto err;
+	}
+	sw->uid = header->uid;
+
+	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), aborting\n",
+			header->data_crc32, crc);
+		goto err;
+	}
+
+	if (header->device_rom_revision > 1)
+		tb_sw_warn(sw, "drom device_rom_revision %#x unknown\n",
+			header->device_rom_revision);
+
+	return tb_drom_parse_entries(sw);
+err:
+	kfree(sw->drom);
+	return -EIO;
+
+}
diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
index c2a24b6..9dfb8e1 100644
--- a/drivers/thunderbolt/switch.c
+++ b/drivers/thunderbolt/switch.c
@@ -400,7 +400,7 @@ struct tb_switch *tb_switch_alloc(struct tb *tb, u64 route)
 	}
 	sw->cap_plug_events = cap;
 
-	if (tb_eeprom_read_uid(sw, &sw->uid))
+	if (tb_drom_read_uid_only(sw, &sw->uid))
 		tb_sw_warn(sw, "could not read uid from eeprom\n");
 	else
 		tb_sw_info(sw, "uid: %#llx\n", sw->uid);
@@ -442,7 +442,7 @@ int tb_switch_resume(struct tb_switch *sw)
 	u64 uid;
 	tb_sw_info(sw, "resuming switch\n");
 
-	err = tb_eeprom_read_uid(sw, &uid);
+	err = tb_drom_read_uid_only(sw, &uid);
 	if (err) {
 		tb_sw_warn(sw, "uid read failed\n");
 		return err;
diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index 63e89d0..18ade5e 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -22,6 +22,7 @@ struct tb_switch {
 	u64 uid;
 	int cap_plug_events; /* offset, zero if not found */
 	bool is_unplugged; /* unplugged, will go away */
+	u8 *drom;
 };
 
 /**
@@ -33,6 +34,9 @@ struct tb_port {
 	struct tb_port *remote; /* remote port, NULL if not connected */
 	int cap_phy; /* offset, zero if not found */
 	u8 port; /* port number on switch */
+	bool disabled; /* disabled by eeprom */
+	struct tb_port *dual_link_port;
+	u8 link_nr:1;
 };
 
 /**
@@ -237,7 +241,8 @@ int tb_path_activate(struct tb_path *path);
 void tb_path_deactivate(struct tb_path *path);
 bool tb_path_is_invalid(struct tb_path *path);
 
-int tb_eeprom_read_uid(struct tb_switch *sw, u64 *uid);
+int tb_drom_read(struct tb_switch *sw);
+int tb_drom_read_uid_only(struct tb_switch *sw, u64 *uid);
 
 
 static inline int tb_route_length(u64 route)
-- 
2.0.0

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