[RFC PATCH 0/8] firewire: core: support legacy layout of configuration ROM for AV/C device

[RFC PATCH 0/8] firewire: core: support legacy layout of configuration ROM for AV/C device

[Takashi Sakamoto]

Hi,

Current core function of Linux FireWire subsystem partly supports legacy
layout of configuration ROM, described in annex of 1394TA document[1]. It
appears that some users have the demand of full support[2]. The series of
change is to satisfy the demand.

The change relates to driver matching procedure and notification to user
space, thus could easily bring functional regression. For safe, the series
includes KUnit application to test the change.

However, backward incompatibility is inevitable due to change of modalias
for unit device. As long as I investigated, any unit drivers in kernel
are not affected by the change. Additionally, less applications in user
space are not as well. I think we can be optimistic to the regression.

Anyway, I'm pleased if receiving your comment or test report about the
change.

[1] Configuration ROM for AV/C Devices 1.0 (December 12, 2000, 1394
    Trading Association, TA Document 1999027)
https://web.archive.org/web/20210216003030/http://1394ta.org/wp-content/uploads/2015/07/1999027.pdf
[2] [PATCH] Fix missing sysfs vendor/model entries for some devices
https://sourceforge.net/p/linux1394/mailman/message/55802731/


Regards


Takashi Sakamoto (8):
  firewire: core: adds constant qualifier for local helper functions
  firewire: core: replace magic number with macro
  firewire: test: add KUnit test for internal CSR API
  firewire: test: add test of CSR API for simple AV/C device
  firewire: test: add test of CSR API for legacy AV/C device
  firewire: core: detect numeric model identifier for legacy layout of
    configuration ROM
  firewire: core: detect model name for legacy layout of configuration
    ROM
  firewire: core: change modalias of unit device with backward
    incompatibility

 drivers/firewire/.kunitconfig   |   1 +
 drivers/firewire/Kconfig        |  16 ++
 drivers/firewire/core-device.c  | 117 +++++++++++----
 drivers/firewire/csr-api-test.c | 251 ++++++++++++++++++++++++++++++++
 4 files changed, 358 insertions(+), 27 deletions(-)
 create mode 100644 drivers/firewire/csr-api-test.c

-- 
2.39.2

[RFC PATCH 1/8] firewire: core: adds constant qualifier for local helper functions

[Takashi Sakamoto]

Some local functions just handles given argument as mutable, thus it is
preferable to add constant qualifier to them.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
---
 drivers/firewire/core-device.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index aa597cda0d88..16c32cb38f0f 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -171,7 +171,7 @@ static const struct ieee1394_device_id *unit_match(struct device *dev,
 	return NULL;
 }
 
-static bool is_fw_unit(struct device *dev);
+static bool is_fw_unit(const struct device *dev);
 
 static int fw_unit_match(struct device *dev, struct device_driver *drv)
 {
@@ -679,7 +679,7 @@ static struct device_type fw_unit_type = {
 	.release	= fw_unit_release,
 };
 
-static bool is_fw_unit(struct device *dev)
+static bool is_fw_unit(const struct device *dev)
 {
 	return dev->type == &fw_unit_type;
 }
@@ -838,7 +838,7 @@ static struct device_type fw_device_type = {
 	.release = fw_device_release,
 };
 
-static bool is_fw_device(struct device *dev)
+static bool is_fw_device(const struct device *dev)
 {
 	return dev->type == &fw_device_type;
 }
-- 
2.39.2

[RFC PATCH 2/8] firewire: core: replace magic number with macro

[Takashi Sakamoto]

In IEEE 1394 specification, the size of bus information block of
configuration ROM is fixed to 5, thus the offset of root directory is 5.
Current implementation to handle device structures has the hard-coded
offset.

This commit replaces the offset with macro.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
---
 drivers/firewire/core-device.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index 16c32cb38f0f..137001f8a695 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -31,6 +31,8 @@
 
 #include "core.h"
 
+#define ROOT_DIR_OFFSET	5
+
 void fw_csr_iterator_init(struct fw_csr_iterator *ci, const u32 *p)
 {
 	ci->p = p + 1;
@@ -135,7 +137,7 @@ static void get_ids(const u32 *directory, int *id)
 
 static void get_modalias_ids(const struct fw_unit *unit, int *id)
 {
-	get_ids(&fw_parent_device(unit)->config_rom[5], id);
+	get_ids(&fw_parent_device(unit)->config_rom[ROOT_DIR_OFFSET], id);
 	get_ids(unit->directory, id);
 }
 
@@ -259,7 +261,7 @@ static ssize_t show_immediate(struct device *dev,
 	if (is_fw_unit(dev))
 		dir = fw_unit(dev)->directory;
 	else
-		dir = fw_device(dev)->config_rom + 5;
+		dir = fw_device(dev)->config_rom + ROOT_DIR_OFFSET;
 
 	fw_csr_iterator_init(&ci, dir);
 	while (fw_csr_iterator_next(&ci, &key, &value))
@@ -292,7 +294,7 @@ static ssize_t show_text_leaf(struct device *dev,
 	if (is_fw_unit(dev))
 		dir = fw_unit(dev)->directory;
 	else
-		dir = fw_device(dev)->config_rom + 5;
+		dir = fw_device(dev)->config_rom + ROOT_DIR_OFFSET;
 
 	if (buf) {
 		bufsize = PAGE_SIZE - 1;
@@ -446,7 +448,7 @@ static ssize_t units_show(struct device *dev,
 	int key, value, i = 0;
 
 	down_read(&fw_device_rwsem);
-	fw_csr_iterator_init(&ci, &device->config_rom[5]);
+	fw_csr_iterator_init(&ci, &device->config_rom[ROOT_DIR_OFFSET]);
 	while (fw_csr_iterator_next(&ci, &key, &value)) {
 		if (key != (CSR_UNIT | CSR_DIRECTORY))
 			continue;
@@ -691,7 +693,7 @@ static void create_units(struct fw_device *device)
 	int key, value, i;
 
 	i = 0;
-	fw_csr_iterator_init(&ci, &device->config_rom[5]);
+	fw_csr_iterator_init(&ci, &device->config_rom[ROOT_DIR_OFFSET]);
 	while (fw_csr_iterator_next(&ci, &key, &value)) {
 		if (key != (CSR_UNIT | CSR_DIRECTORY))
 			continue;
-- 
2.39.2

[RFC PATCH 3/8] firewire: test: add KUnit test for internal CSR API

[Takashi Sakamoto]

The operation over CSR space is important since it is related to detection
of nodes and units, addition of system devices. Any test of the operation
is enough useful.

This commit adds a skeleton of KUnit test for the purpose.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
---
 drivers/firewire/.kunitconfig   |  1 +
 drivers/firewire/Kconfig        | 16 ++++++++++++++++
 drivers/firewire/core-device.c  |  4 ++++
 drivers/firewire/csr-api-test.c | 19 +++++++++++++++++++
 4 files changed, 40 insertions(+)
 create mode 100644 drivers/firewire/csr-api-test.c

diff --git a/drivers/firewire/.kunitconfig b/drivers/firewire/.kunitconfig
index 1599e069395f..03104cdd06eb 100644
--- a/drivers/firewire/.kunitconfig
+++ b/drivers/firewire/.kunitconfig
@@ -2,3 +2,4 @@ CONFIG_KUNIT=y
 CONFIG_PCI=y
 CONFIG_FIREWIRE=y
 CONFIG_FIREWIRE_KUNIT_UAPI_TEST=y
+CONFIG_FIREWIRE_KUNIT_CSR_API_TEST=y
diff --git a/drivers/firewire/Kconfig b/drivers/firewire/Kconfig
index 0a6596b027db..184906fdb77a 100644
--- a/drivers/firewire/Kconfig
+++ b/drivers/firewire/Kconfig
@@ -34,6 +34,22 @@ config FIREWIRE_KUNIT_UAPI_TEST
 	  For more information on KUnit and unit tests in general, refer
 	  to the KUnit documentation in Documentation/dev-tools/kunit/.
 
+config FIREWIRE_KUNIT_CSR_API_TEST
+	tristate "KUnit tests for internal CSR API" if !KUNIT_ALL_TESTS
+	depends on FIREWIRE && KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  This builds the KUnit tests for internal API for Control and
+	  Status Registers.
+
+	  KUnit tests run during boot and output the results to the debug
+	  log in TAP format (https://testanything.org/). Only useful for
+	  kernel devs running KUnit test harness and are not for inclusion
+	  into a production build.
+
+	  For more information on KUnit and unit tests in general, refer
+	  to the KUnit documentation in Documentation/dev-tools/kunit/.
+
 config FIREWIRE_OHCI
 	tristate "OHCI-1394 controllers"
 	depends on PCI && FIREWIRE && MMU
diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index 137001f8a695..14c7461c05f6 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -1313,3 +1313,7 @@ void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
 		break;
 	}
 }
+
+#ifdef CONFIG_FIREWIRE_KUNIT_CSR_API_TEST
+#include "csr-api-test.c"
+#endif
diff --git a/drivers/firewire/csr-api-test.c b/drivers/firewire/csr-api-test.c
new file mode 100644
index 000000000000..a76d767373e9
--- /dev/null
+++ b/drivers/firewire/csr-api-test.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0-only
+//
+// csr-api-test.c - An application of Kunit to test implementation for CSR operation.
+//
+// Copyright (c) 2023 Takashi Sakamoto
+//
+// This file can not be built independently since it is intentionally included in core-device.c.
+
+#include <kunit/test.h>
+
+static struct kunit_case csr_api_test_cases[] = {
+	{}
+};
+
+static struct kunit_suite csr_api_test_suite = {
+	.name = "firewire-csr-api",
+	.test_cases = csr_api_test_cases,
+};
+kunit_test_suite(csr_api_test_suite);
-- 
2.39.2

[RFC PATCH 4/8] firewire: test: add test of CSR API for simple AV/C device

[Takashi Sakamoto]

At present, core function can handle node which has configuration ROM
similar to AV/C device somehow. The standard layout of configuration ROM
for AV/C device is described in the following document.

- Configuration ROM for AV/C Devices 1.0 (Dec. 12, 2000, 1394 Trading
  Association)

This commit adds a KUnit test for this case. The following output is the
parse result by config-rom-pretty-printer in linux-firewire-utils
(https://git.kernel.org/pub/scm/utils/ieee1394/linux-firewire-utils.git/).

$ config-rom-pretty-printer < /tmp/rom.img
               ROM header and bus information block
               -----------------------------------------------------------------
1024  0404eabf  bus_info_length 4, crc_length 4, crc 60095
1028  31333934  bus_name "1394"
1032  e0646102  irmc 1, cmc 1, isc 1, bmc 0, cyc_clk_acc 100, max_rec 6 (128)
1036  ffffffff  company_id ffffff     |
1040  ffffffff  device_id 1099511627775  | EUI-64 18446744073709551615

               root directory
               -----------------------------------------------------------------
1044  00063287  directory_length 6, crc 12935
1048  03ffffff  vendor
1052  8100000a  --> descriptor leaf at 1092
1056  17ffffff  model
1060  8100000e  --> descriptor leaf at 1116
1064  0c0083c0  node capabilities: per IEEE 1394
1068  d1000001  --> unit directory at 1072

               unit directory at 1072
               -----------------------------------------------------------------
1072  0004442d  directory_length 4, crc 17453
1076  1200a02d  specifier id
1080  13010001  version
1084  17ffffff  model
1088  81000007  --> descriptor leaf at 1116

               descriptor leaf at 1092
               -----------------------------------------------------------------
1092  0005c915  leaf_length 5, crc 51477
1096  00000000  textual descriptor
1100  00000000  minimal ASCII
1104  56656e64  "Vend"
1108  6f72204e  "or N"
1112  616d6500  "ame"

               descriptor leaf at 1116
               -----------------------------------------------------------------
1116  00057f16  leaf_length 5, crc 32534
1120  00000000  textual descriptor
1124  00000000  minimal ASCII
1128  4d6f6465  "Mode"
1132  6c204e61  "l Na"
1136  6d650000  "me"

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
---
 drivers/firewire/csr-api-test.c | 119 ++++++++++++++++++++++++++++++++
 1 file changed, 119 insertions(+)

diff --git a/drivers/firewire/csr-api-test.c b/drivers/firewire/csr-api-test.c
index a76d767373e9..d91852825efc 100644
--- a/drivers/firewire/csr-api-test.c
+++ b/drivers/firewire/csr-api-test.c
@@ -8,7 +8,126 @@
 
 #include <kunit/test.h>
 
+// Configuration ROM for AV/C Devices 1.0 (Dec. 12, 2000, 1394 Trading Association)
+// Annex C:Configuration ROM example(informative)
+// C.1 Simple AV/C device
+//
+// Copied from the documentation.
+static const u32 simple_avc_device[] = {
+	0x0404eabf,
+	0x31333934,
+	0xe0646102,
+	0xffffffff,
+	0xffffffff,
+	0x00063287, // root directory.
+	0x03ffffff,
+	0x8100000a,
+	0x17ffffff,
+	0x8100000e,
+	0x0c0083c0,
+	0xd1000001,
+	0x0004442d, // unit 0 directory.
+	0x1200a02d,
+	0x13010001,
+	0x17ffffff,
+	0x81000007,
+	0x0005c915, // leaf.
+	0x00000000,
+	0x00000000,
+	0x56656e64,
+	0x6f72204e,
+	0x616d6500,
+	0x00057f16, // leaf.
+	0x00000000,
+	0x00000000,
+	0x4d6f6465,
+	0x6c204e61,
+	0x6d650000,
+};
+
+static void csr_api_simple_avc_device(struct kunit *test)
+{
+	static const struct fw_device node = {
+		.device = {
+			.type = &fw_device_type,
+		},
+		.config_rom = simple_avc_device,
+		.config_rom_length = sizeof(simple_avc_device),
+	};
+	static const struct fw_unit unit0 = {
+		.device = {
+			.type = &fw_unit_type,
+			.parent = (struct device *)&node.device,
+		},
+		.directory = &simple_avc_device[12],
+	};
+	struct device *node_dev = (struct device *)&node.device;
+	struct device *unit0_dev = (struct device *)&unit0.device;
+	static const int unit_expected_ids[] = {0x00ffffff, 0x00ffffff, 0x0000a02d, 0x00010001};
+	char *buf = kunit_kzalloc(test, PAGE_SIZE, GFP_KERNEL);
+	int ids[4] = {0, 0, 0, 0};
+
+	// Ensure associations for node and unit devices.
+
+	KUNIT_ASSERT_TRUE(test, is_fw_device(node_dev));
+	KUNIT_ASSERT_FALSE(test, is_fw_unit(node_dev));
+	KUNIT_ASSERT_PTR_EQ(test, fw_device(node_dev), &node);
+
+	KUNIT_ASSERT_FALSE(test, is_fw_device(unit0_dev));
+	KUNIT_ASSERT_TRUE(test, is_fw_unit(unit0_dev));
+	KUNIT_ASSERT_PTR_EQ(test, fw_parent_device((&unit0)), &node);
+	KUNIT_ASSERT_PTR_EQ(test, fw_unit(unit0_dev), &unit0);
+
+	// For entries in root directory.
+
+	// Vendor immediate entry is found.
+	KUNIT_EXPECT_GT(test, show_immediate(node_dev, &config_rom_attributes[0].attr, buf), 0);
+	KUNIT_EXPECT_STREQ(test, buf, "0xffffff\n");
+
+	// Model immediate entry is found.
+	KUNIT_EXPECT_GT(test, show_immediate(node_dev, &config_rom_attributes[4].attr, buf), 0);
+	KUNIT_EXPECT_STREQ(test, buf, "0xffffff\n");
+
+	// Descriptor leaf entry for vendor is found.
+	KUNIT_EXPECT_GT(test, show_text_leaf(node_dev, &config_rom_attributes[5].attr, buf), 0);
+	KUNIT_EXPECT_STREQ(test, buf, "Vendor Name\n");
+
+	// Descriptor leaf entry for model is found.
+	KUNIT_EXPECT_GT(test, show_text_leaf(node_dev, &config_rom_attributes[6].attr, buf), 0);
+	KUNIT_EXPECT_STREQ(test, buf, "Model Name\n");
+
+	// For entries in unit 0 directory.
+
+	// Vendor immediate entry is not found.
+	KUNIT_EXPECT_LT(test, show_immediate(unit0_dev, &config_rom_attributes[0].attr, buf), 0);
+
+	// Model immediate entry is found.
+	KUNIT_EXPECT_GT(test, show_immediate(unit0_dev, &config_rom_attributes[4].attr, buf), 0);
+	KUNIT_EXPECT_STREQ(test, buf, "0xffffff\n");
+
+	// Descriptor leaf entry for vendor is not found.
+	KUNIT_EXPECT_LT(test, show_text_leaf(unit0_dev, &config_rom_attributes[5].attr, buf), 0);
+
+	// Descriptor leaf entry for model is not found.
+	KUNIT_EXPECT_GT(test, show_text_leaf(unit0_dev, &config_rom_attributes[6].attr, buf), 0);
+	KUNIT_EXPECT_STREQ(test, buf, "Model Name\n");
+
+	// Specifier_ID immediate entry is found.
+	KUNIT_EXPECT_GT(test, show_immediate(unit0_dev, &config_rom_attributes[2].attr, buf), 0);
+	KUNIT_EXPECT_STREQ(test, buf, "0x00a02d\n");
+
+	// Version immediate entry is found.
+	KUNIT_EXPECT_GT(test, show_immediate(unit0_dev, &config_rom_attributes[3].attr, buf), 0);
+	KUNIT_EXPECT_STREQ(test, buf, "0x010001\n");
+
+	kunit_kfree(test, buf);
+
+	get_modalias_ids(&unit0, ids);
+	KUNIT_EXPECT_MEMEQ(test, ids, unit_expected_ids, sizeof(ids));
+}
+
 static struct kunit_case csr_api_test_cases[] = {
+	KUNIT_CASE(csr_api_simple_avc_device),
 	{}
 };
 
-- 
2.39.2

[RFC PATCH 5/8] firewire: test: add test of CSR API for legacy AV/C device

[Takashi Sakamoto]

Some legacy devices have configuration ROM against standard AV/C device.
They have vendor directory to store model identifier. It is described in
annex of the following document.

- Configuration ROM for AV/C Devices 1.0 (Dec. 12, 2000, 1394 Trading
  Association)

In the case, current implementation of core function does not detect the
model identifier, thus device attributes and modalias of unit have lack of
it. Another KUnit test is required for the case.

The following output is the parse result by config-rom-pretty-printer in
linux-firewire-utils
(https://git.kernel.org/pub/scm/utils/ieee1394/linux-firewire-utils.git/).
The content of image is written by my hand.

$ config-rom-pretty-printer < /tmp/rom.img
               ROM header and bus information block
               -----------------------------------------------------------------
1024  04199fe7  bus_info_length 4, crc_length 25, crc 40935
1028  31333934  bus_name "1394"
1032  e0644000  irmc 1, cmc 1, isc 1, bmc 0, cyc_clk_acc 100, max_rec 4 (32)
1036  00112233  company_id 001122     |
1040  44556677  device_id 220189779575  | EUI-64 4822678189205111

               root directory
               -----------------------------------------------------------------
1044  0005dace  directory_length 5, crc 56014
1048  03012345  vendor
1052  0c0083c0  node capabilities: per IEEE 1394
1056  8d000009  --> eui-64 leaf at 1092
1060  d1000002  --> unit directory at 1068
1064  c3000004  --> vendor directory at 1080

               unit directory at 1068
               -----------------------------------------------------------------
1068  0002e107  directory_length 2, crc 57607
1072  12abcdef  specifier id
1076  13543210  version

               vendor directory at 1080
               -----------------------------------------------------------------
1080  0002cb73  directory_length 2, crc 52083
1084  17fedcba  model
1088  81000004  --> descriptor leaf at 1104

               eui-64 leaf at 1092
               -----------------------------------------------------------------
1092  00026dc1  leaf_length 2, crc 28097
1096  00112233  company_id 001122     |
1100  44556677  device_id 220189779575  | EUI-64 4822678189205111

               descriptor leaf at 1104
               -----------------------------------------------------------------
1104  00050e84  leaf_length 5, crc 3716
1108  00000000  textual descriptor
1112  00000000  minimal ASCII
1116  41424344  "ABCD"
1120  45464748  "EFGH"
1124  494a0000  "IJ"

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
---
 drivers/firewire/csr-api-test.c | 111 ++++++++++++++++++++++++++++++++
 1 file changed, 111 insertions(+)

diff --git a/drivers/firewire/csr-api-test.c b/drivers/firewire/csr-api-test.c
index d91852825efc..2430891c5dcb 100644
--- a/drivers/firewire/csr-api-test.c
+++ b/drivers/firewire/csr-api-test.c
@@ -45,6 +45,40 @@ static const u32 simple_avc_device[] = {
 	0x6d650000,
 };
 
+// Ibid.
+// Annex A:Consideration for configuration ROM reader design (informative)
+// A.1 Vendor directory
+//
+// Written by hand.
+static const u32 legacy_avc_device[] = {
+	0x04199fe7,
+	0x31333934,
+	0xe0644000,
+	0x00112233,
+	0x44556677,
+	0x0005dace, // root directory.
+	0x03012345,
+	0x0c0083c0,
+	0x8d000009,
+	0xd1000002,
+	0xc3000004,
+	0x0002e107, // unit 0 directory.
+	0x12abcdef,
+	0x13543210,
+	0x0002cb73, // vendor directory.
+	0x17fedcba,
+	0x81000004,
+	0x00026dc1, // leaf for EUI-64.
+	0x00112233,
+	0x44556677,
+	0x00050e84, // leaf for text descriptor.
+	0x00000000,
+	0x00000000,
+	0x41424344,
+	0x45464748,
+	0x494a0000,
+};
+
 static void csr_api_simple_avc_device(struct kunit *test)
 {
 	static const struct fw_device node = {
@@ -126,8 +160,85 @@ static void csr_api_simple_avc_device(struct kunit *test)
 	KUNIT_EXPECT_MEMEQ(test, ids, unit_expected_ids, sizeof(ids));
 }
 
+static void csr_api_legacy_avc_device(struct kunit *test)
+{
+	static const struct fw_device node = {
+		.device = {
+			.type = &fw_device_type,
+		},
+		.config_rom = legacy_avc_device,
+		.config_rom_length = sizeof(legacy_avc_device),
+	};
+	static const struct fw_unit unit0 = {
+		.device = {
+			.type = &fw_unit_type,
+			.parent = (struct device *)&node.device,
+		},
+		.directory = &legacy_avc_device[11],
+	};
+	struct device *node_dev = (struct device *)&node.device;
+	struct device *unit0_dev = (struct device *)&unit0.device;
+	static const int unit_expected_ids[] = {0x00012345, 0x00000000, 0x00abcdef, 0x00543210};
+	char *buf = kunit_kzalloc(test, PAGE_SIZE, GFP_KERNEL);
+	int ids[4] = {0, 0, 0, 0};
+
+	// Ensure associations for node and unit devices.
+
+	KUNIT_ASSERT_TRUE(test, is_fw_device(node_dev));
+	KUNIT_ASSERT_FALSE(test, is_fw_unit(node_dev));
+	KUNIT_ASSERT_PTR_EQ(test, fw_device((node_dev)), &node);
+
+	KUNIT_ASSERT_FALSE(test, is_fw_device(unit0_dev));
+	KUNIT_ASSERT_TRUE(test, is_fw_unit(unit0_dev));
+	KUNIT_ASSERT_PTR_EQ(test, fw_parent_device((&unit0)), &node);
+	KUNIT_ASSERT_PTR_EQ(test, fw_unit(unit0_dev), &unit0);
+
+	// For entries in root directory.
+
+	// Vendor immediate entry is found.
+	KUNIT_EXPECT_GT(test, show_immediate(node_dev, &config_rom_attributes[0].attr, buf), 0);
+	KUNIT_EXPECT_STREQ(test, buf, "0x012345\n");
+
+	// Model immediate entry is not found.
+	KUNIT_EXPECT_LT(test, show_immediate(node_dev, &config_rom_attributes[4].attr, buf), 0);
+
+	// Descriptor leaf entry for vendor is not found.
+	KUNIT_EXPECT_LT(test, show_text_leaf(node_dev, &config_rom_attributes[5].attr, buf), 0);
+
+	// Descriptor leaf entry for model is not found.
+	KUNIT_EXPECT_LT(test, show_text_leaf(node_dev, &config_rom_attributes[6].attr, buf), 0);
+
+	// For entries in unit 0 directory.
+
+	// Vendor immediate entry is not found.
+	KUNIT_EXPECT_LT(test, show_immediate(unit0_dev, &config_rom_attributes[0].attr, buf), 0);
+
+	// Model immediate entry is not found.
+	KUNIT_EXPECT_LT(test, show_immediate(unit0_dev, &config_rom_attributes[4].attr, buf), 0);
+
+	// Descriptor leaf entry for vendor is not found.
+	KUNIT_EXPECT_LT(test, show_text_leaf(unit0_dev, &config_rom_attributes[5].attr, buf), 0);
+
+	// Descriptor leaf entry for model is not found.
+	KUNIT_EXPECT_LT(test, show_text_leaf(unit0_dev, &config_rom_attributes[6].attr, buf), 0);
+
+	// Specifier_ID immediate entry is found.
+	KUNIT_EXPECT_GT(test, show_immediate(unit0_dev, &config_rom_attributes[2].attr, buf), 0);
+	KUNIT_EXPECT_STREQ(test, buf, "0xabcdef\n");
+
+	// Version immediate entry is found.
+	KUNIT_EXPECT_GT(test, show_immediate(unit0_dev, &config_rom_attributes[3].attr, buf), 0);
+	KUNIT_EXPECT_STREQ(test, buf, "0x543210\n");
+
+	kunit_kfree(test, buf);
+
+	get_modalias_ids(&unit0, ids);
+	KUNIT_EXPECT_MEMEQ(test, ids, unit_expected_ids, sizeof(ids));
+}
+
 static struct kunit_case csr_api_test_cases[] = {
 	KUNIT_CASE(csr_api_simple_avc_device),
+	KUNIT_CASE(csr_api_legacy_avc_device),
 	{}
 };
 
-- 
2.39.2

[RFC PATCH 6/8] firewire: core: detect numeric model identifier for legacy layout of configuration ROM

[Takashi Sakamoto]

As the part of support for legacy layout of configuration ROM, this
commit traverse vendor directory as well as root directory when showing
device attribute for node device. This change expects 'model' attribute
appears in node device, however it is probable to see the other types of
immediate values if the vendor directory includes.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
---
 drivers/firewire/core-device.c  | 57 +++++++++++++++++++++++++--------
 drivers/firewire/csr-api-test.c |  5 +--
 2 files changed, 47 insertions(+), 15 deletions(-)

diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index 14c7461c05f6..dad5c9937b78 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -49,6 +49,22 @@ int fw_csr_iterator_next(struct fw_csr_iterator *ci, int *key, int *value)
 }
 EXPORT_SYMBOL(fw_csr_iterator_next);
 
+static const u32 *search_directory(const u32 *directory, int search_key)
+{
+	struct fw_csr_iterator ci;
+	int key, value;
+
+	search_key |= CSR_DIRECTORY;
+
+	fw_csr_iterator_init(&ci, directory);
+	while (fw_csr_iterator_next(&ci, &key, &value)) {
+		if (key == search_key)
+			return ci.p - 1 + value;
+	}
+
+	return NULL;
+}
+
 static const u32 *search_leaf(const u32 *directory, int search_key)
 {
 	struct fw_csr_iterator ci;
@@ -253,27 +269,42 @@ static ssize_t show_immediate(struct device *dev,
 	struct config_rom_attribute *attr =
 		container_of(dattr, struct config_rom_attribute, attr);
 	struct fw_csr_iterator ci;
-	const u32 *dir;
-	int key, value, ret = -ENOENT;
+	const u32 *directories[] = {NULL, NULL};
+	int i, value = -1;
 
 	down_read(&fw_device_rwsem);
 
-	if (is_fw_unit(dev))
-		dir = fw_unit(dev)->directory;
-	else
-		dir = fw_device(dev)->config_rom + ROOT_DIR_OFFSET;
+	if (is_fw_unit(dev)) {
+		directories[0] = fw_unit(dev)->directory;
+	} else {
+		const u32 *root_directory = fw_device(dev)->config_rom + ROOT_DIR_OFFSET;
 
-	fw_csr_iterator_init(&ci, dir);
-	while (fw_csr_iterator_next(&ci, &key, &value))
-		if (attr->key == key) {
-			ret = snprintf(buf, buf ? PAGE_SIZE : 0,
-				       "0x%06x\n", value);
-			break;
+		directories[0] = root_directory;
+
+		// Legacy layout of configuration ROM described in Annex 1 of 'Configuration ROM
+		// for AV/C Devices 1.0 (December 12, 2000, 1394 Trading Association, TA Document
+		// 1999027)'.
+		directories[1] = search_directory(root_directory, CSR_VENDOR);
+	}
+
+	for (i = 0; i < ARRAY_SIZE(directories) && !!directories[i]; ++i) {
+		int key, val;
+
+		fw_csr_iterator_init(&ci, directories[i]);
+		while (fw_csr_iterator_next(&ci, &key, &val)) {
+			if (attr->key == key) {
+				value = val;
+				break;
+			}
 		}
+	}
 
 	up_read(&fw_device_rwsem);
 
-	return ret;
+	if (value < 0)
+		return -ENOENT;
+
+	return snprintf(buf, buf ? PAGE_SIZE : 0, "0x%06x\n", value);
 }
 
 #define IMMEDIATE_ATTR(name, key)				\
diff --git a/drivers/firewire/csr-api-test.c b/drivers/firewire/csr-api-test.c
index 2430891c5dcb..7278e7b927a8 100644
--- a/drivers/firewire/csr-api-test.c
+++ b/drivers/firewire/csr-api-test.c
@@ -199,8 +199,9 @@ static void csr_api_legacy_avc_device(struct kunit *test)
 	KUNIT_EXPECT_GT(test, show_immediate(node_dev, &config_rom_attributes[0].attr, buf), 0);
 	KUNIT_EXPECT_STREQ(test, buf, "0x012345\n");
 
-	// Model immediate entry is not found.
-	KUNIT_EXPECT_LT(test, show_immediate(node_dev, &config_rom_attributes[4].attr, buf), 0);
+	// Model immediate entry is found.
+	KUNIT_EXPECT_GT(test, show_immediate(node_dev, &config_rom_attributes[4].attr, buf), 0);
+	KUNIT_EXPECT_STREQ(test, buf, "0xfedcba\n");
 
 	// Descriptor leaf entry for vendor is not found.
 	KUNIT_EXPECT_LT(test, show_text_leaf(node_dev, &config_rom_attributes[5].attr, buf), 0);
-- 
2.39.2

[RFC PATCH 7/8] firewire: core: detect model name for legacy layout of configuration ROM

[Takashi Sakamoto]

As the part of support for legacy layout of configuration ROM, this
commit traverse vendor directory as well as root directory when showing
device attribute for node device. This change expects 'model_name'
attribute appears in node device, however it is probable to see the other
types of descriptor leaf if the vendor directory includes.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
---
 drivers/firewire/core-device.c  | 23 ++++++++++++++++-------
 drivers/firewire/csr-api-test.c |  5 +++--
 2 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index dad5c9937b78..f7a11004f972 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -315,17 +315,25 @@ static ssize_t show_text_leaf(struct device *dev,
 {
 	struct config_rom_attribute *attr =
 		container_of(dattr, struct config_rom_attribute, attr);
-	const u32 *dir;
+	const u32 *directories[] = {NULL, NULL};
 	size_t bufsize;
 	char dummy_buf[2];
-	int ret;
+	int i, ret;
 
 	down_read(&fw_device_rwsem);
 
-	if (is_fw_unit(dev))
-		dir = fw_unit(dev)->directory;
-	else
-		dir = fw_device(dev)->config_rom + ROOT_DIR_OFFSET;
+	if (is_fw_unit(dev)) {
+		directories[0] = fw_unit(dev)->directory;
+	} else {
+		const u32 *root_directory = fw_device(dev)->config_rom + ROOT_DIR_OFFSET;
+
+		directories[0] = root_directory;
+
+		// Legacy layout of configuration ROM described in Annex 1 of 'Configuration ROM
+		// for AV/C Devices 1.0 (December 12, 2000, 1394 Trading Association, TA Document
+		// 1999027)'.
+		directories[1] = search_directory(root_directory, CSR_VENDOR);
+	}
 
 	if (buf) {
 		bufsize = PAGE_SIZE - 1;
@@ -334,7 +342,8 @@ static ssize_t show_text_leaf(struct device *dev,
 		bufsize = 1;
 	}
 
-	ret = fw_csr_string(dir, attr->key, buf, bufsize);
+	for (i = 0; i < ARRAY_SIZE(directories) && directories[i]; ++i)
+		ret = fw_csr_string(directories[i], attr->key, buf, bufsize);
 
 	if (ret >= 0) {
 		/* Strip trailing whitespace and add newline. */
diff --git a/drivers/firewire/csr-api-test.c b/drivers/firewire/csr-api-test.c
index 7278e7b927a8..779146d0cfba 100644
--- a/drivers/firewire/csr-api-test.c
+++ b/drivers/firewire/csr-api-test.c
@@ -206,8 +206,9 @@ static void csr_api_legacy_avc_device(struct kunit *test)
 	// Descriptor leaf entry for vendor is not found.
 	KUNIT_EXPECT_LT(test, show_text_leaf(node_dev, &config_rom_attributes[5].attr, buf), 0);
 
-	// Descriptor leaf entry for model is not found.
-	KUNIT_EXPECT_LT(test, show_text_leaf(node_dev, &config_rom_attributes[6].attr, buf), 0);
+	// Descriptor leaf entry for model is found.
+	KUNIT_EXPECT_GT(test, show_text_leaf(node_dev, &config_rom_attributes[6].attr, buf), 0);
+	KUNIT_EXPECT_STREQ(test, buf, "ABCDEFGHIJ\n");
 
 	// For entries in unit 0 directory.
 
-- 
2.39.2

[RFC PATCH 8/8] firewire: core: change modalias of unit device and loss of backward compatibility

[Takashi Sakamoto]

As the last part of support for legacy layout of configuration ROM, this
commit traverse vendor directory as well as root directory when
constructing modalias for unit device. The change brings loss of backward
compatibility since it can fill 'mo' field which is 0 at current
implementation in the case. However, we can be optimistic against
regression for unit drivers in kernel, due to some points:

1. ALSA drivers for audio and music units uses Model fields to match
   device, however all of supported devices does not have such legacy
   layout.
2. the other unit drivers does not use Model field to match device.

The rest of concern is user space application. The most of application
just take care of node device and does not use the modalias of unit
device, thus the change does not affect to them. Although, systemd
project gets affects since it includes hwdb to take udev to configure
fw character device conveniently. I have a plan to work systemd so that
the access permission of character device is kept for the previous and
next version of Linux kernel.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
---
 drivers/firewire/core-device.c  | 21 +++++++++++++++++++--
 drivers/firewire/csr-api-test.c |  2 +-
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index f7a11004f972..e04486c5e0eb 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -153,8 +153,25 @@ static void get_ids(const u32 *directory, int *id)
 
 static void get_modalias_ids(const struct fw_unit *unit, int *id)
 {
-	get_ids(&fw_parent_device(unit)->config_rom[ROOT_DIR_OFFSET], id);
-	get_ids(unit->directory, id);
+	const u32 *root_directory = &fw_parent_device(unit)->config_rom[ROOT_DIR_OFFSET];
+	const u32 *directories[] = {NULL, NULL, NULL};
+	const u32 *vendor_directory;
+	int i;
+
+	directories[0] = root_directory;
+
+	// Legacy layout of configuration ROM described in Annex 1 of 'Configuration ROM for AV/C
+	// Devices 1.0 (December 12, 2000, 1394 Trading Association, TA Document 1999027)'.
+	vendor_directory = search_directory(root_directory, CSR_DIRECTORY | CSR_VENDOR);
+	if (!vendor_directory) {
+		directories[1] = unit->directory;
+	} else {
+		directories[1] = vendor_directory;
+		directories[2] = unit->directory;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(directories) && directories[i]; ++i)
+		get_ids(directories[i], id);
 }
 
 static bool match_ids(const struct ieee1394_device_id *id_table, int *id)
diff --git a/drivers/firewire/csr-api-test.c b/drivers/firewire/csr-api-test.c
index 779146d0cfba..753d8e83b8c2 100644
--- a/drivers/firewire/csr-api-test.c
+++ b/drivers/firewire/csr-api-test.c
@@ -178,7 +178,7 @@ static void csr_api_legacy_avc_device(struct kunit *test)
 	};
 	struct device *node_dev = (struct device *)&node.device;
 	struct device *unit0_dev = (struct device *)&unit0.device;
-	static const int unit_expected_ids[] = {0x00012345, 0x00000000, 0x00abcdef, 0x00543210};
+	static const int unit_expected_ids[] = {0x00012345, 0x00fedcba, 0x00abcdef, 0x00543210};
 	char *buf = kunit_kzalloc(test, PAGE_SIZE, GFP_KERNEL);
 	int ids[4] = {0, 0, 0, 0};
 
-- 
2.39.2

[RFC PATCH 8/8] firewire: core: change modalias of unit device with backward incompatibility

[Takashi Sakamoto]

As the last part of support for legacy layout of configuration ROM, this
commit traverse vendor directory as well as root directory when
constructing modalias for unit device. The change brings loss of backward
compatibility since it can fill 'mo' field which is 0 at current
implementation in the case. However, we can be optimistic against
regression for unit drivers in kernel, due to some points:

1. ALSA drivers for audio and music units uses Model fields to match
   device, however all of supported devices does not have such legacy
   layout.
2. the other unit drivers does not use Model field to match device.

The rest of concern is user space application. The most of application
just take care of node device and does not use the modalias of unit
device, thus the change does not affect to them. Although, systemd
project gets affects since it includes hwdb to take udev to configure
fw character device conveniently. I have a plan to work systemd so that
the access permission of character device is kept for the previous and
next version of Linux kernel.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
---
 drivers/firewire/core-device.c  | 21 +++++++++++++++++++--
 drivers/firewire/csr-api-test.c |  2 +-
 2 files changed, 20 insertions(+), 3 deletions(-)

diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index f7a11004f972..e04486c5e0eb 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -153,8 +153,25 @@ static void get_ids(const u32 *directory, int *id)
 
 static void get_modalias_ids(const struct fw_unit *unit, int *id)
 {
-	get_ids(&fw_parent_device(unit)->config_rom[ROOT_DIR_OFFSET], id);
-	get_ids(unit->directory, id);
+	const u32 *root_directory = &fw_parent_device(unit)->config_rom[ROOT_DIR_OFFSET];
+	const u32 *directories[] = {NULL, NULL, NULL};
+	const u32 *vendor_directory;
+	int i;
+
+	directories[0] = root_directory;
+
+	// Legacy layout of configuration ROM described in Annex 1 of 'Configuration ROM for AV/C
+	// Devices 1.0 (December 12, 2000, 1394 Trading Association, TA Document 1999027)'.
+	vendor_directory = search_directory(root_directory, CSR_DIRECTORY | CSR_VENDOR);
+	if (!vendor_directory) {
+		directories[1] = unit->directory;
+	} else {
+		directories[1] = vendor_directory;
+		directories[2] = unit->directory;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(directories) && directories[i]; ++i)
+		get_ids(directories[i], id);
 }
 
 static bool match_ids(const struct ieee1394_device_id *id_table, int *id)
diff --git a/drivers/firewire/csr-api-test.c b/drivers/firewire/csr-api-test.c
index 779146d0cfba..753d8e83b8c2 100644
--- a/drivers/firewire/csr-api-test.c
+++ b/drivers/firewire/csr-api-test.c
@@ -178,7 +178,7 @@ static void csr_api_legacy_avc_device(struct kunit *test)
 	};
 	struct device *node_dev = (struct device *)&node.device;
 	struct device *unit0_dev = (struct device *)&unit0.device;
-	static const int unit_expected_ids[] = {0x00012345, 0x00000000, 0x00abcdef, 0x00543210};
+	static const int unit_expected_ids[] = {0x00012345, 0x00fedcba, 0x00abcdef, 0x00543210};
 	char *buf = kunit_kzalloc(test, PAGE_SIZE, GFP_KERNEL);
 	int ids[4] = {0, 0, 0, 0};
 
-- 
2.39.2

Re: [RFC PATCH 7/8] firewire: core: detect model name for legacy layout of configuration ROM

[Adam Goldman]

Hi,

On Sun, Dec 17, 2023 at 07:30:10PM +0900, Takashi Sakamoto wrote:
> -	ret = fw_csr_string(dir, attr->key, buf, bufsize);
> +	for (i = 0; i < ARRAY_SIZE(directories) && directories[i]; ++i)
> +		ret = fw_csr_string(directories[i], attr->key, buf, bufsize);

I believe this is incorrect. If the attribute is in the first directory 
searched, the loop will continue. The second loop iteration will set ret 
to -ENOENT because the attribute isn't in the second directory. Then 
show_text_leaf will return -ENOENT even though the attribute existed.

-- Adam

Re: [RFC PATCH 8/8] firewire: core: change modalias of unit device with backward incompatibility

[Adam Goldman]

Hi,

On Sun, Dec 17, 2023 at 07:30:12PM +0900, Takashi Sakamoto wrote:
> +	vendor_directory = search_directory(root_directory, CSR_DIRECTORY | CSR_VENDOR);

Setting the CSR_DIRECTORY bit here is extraneous since search_directory() also sets it.

-- Adam

Re: [RFC PATCH 8/8] firewire: core: change modalias of unit device with backward incompatibility

[Takashi Sakamoto]

Hi,

On Mon, Dec 18, 2023 at 02:11:42AM -0800, Adam Goldman wrote:
> Hi,
> 
> On Sun, Dec 17, 2023 at 07:30:12PM +0900, Takashi Sakamoto wrote:
> > +	vendor_directory = search_directory(root_directory, CSR_DIRECTORY | CSR_VENDOR);
> 
> Setting the CSR_DIRECTORY bit here is extraneous since search_directory() also sets it.

Indeed. It is redundant.


Thanks

Takashi Sakamoto

Re: [RFC PATCH 7/8] firewire: core: detect model name for legacy layout of configuration ROM

[Takashi Sakamoto]

Hi,

On Mon, Dec 18, 2023 at 02:04:52AM -0800, Adam Goldman wrote:
> Hi,
> 
> On Sun, Dec 17, 2023 at 07:30:10PM +0900, Takashi Sakamoto wrote:
> > -	ret = fw_csr_string(dir, attr->key, buf, bufsize);
> > +	for (i = 0; i < ARRAY_SIZE(directories) && directories[i]; ++i)
> > +		ret = fw_csr_string(directories[i], attr->key, buf, bufsize);
> 
> I believe this is incorrect. If the attribute is in the first directory 
> searched, the loop will continue. The second loop iteration will set ret 
> to -ENOENT because the attribute isn't in the second directory. Then 
> show_text_leaf will return -ENOENT even though the attribute existed.

Exactly. It is a bug.

I think we can solve it by aligning the pointers of directory in reverse
order within the array, like:

```
diff --git a/drivers/firewire/core-device.c b/drivers/firewire/core-device.c
index d3fc3270a00b..adae3268291f 100644
--- a/drivers/firewire/core-device.c
+++ b/drivers/firewire/core-device.c
@@ -326,13 +326,17 @@ static ssize_t show_text_leaf(struct device *dev,
                directories[0] = fw_unit(dev)->directory;
        } else {
                const u32 *root_directory = fw_device(dev)->config_rom + ROOT_DIR_OFFSET;
+               const u32 *vendor_directory = search_directory(root_directory, CSR_VENDOR);

-               directories[0] = root_directory;
-
-               // Legacy layout of configuration ROM described in Annex 1 of 'Configuration ROM
-               // for AV/C Devices 1.0 (December 12, 2000, 1394 Trading Association, TA Document
-               // 1999027)'.
-               directories[1] = search_directory(root_directory, CSR_VENDOR);
+               if (!vendor_directory) {
+                       directories[0] = root_directory;
+               } else {
+                       // Legacy layout of configuration ROM described in Annex 1 of
+                       // 'Configuration ROM for AV/C Devices 1.0 (December 12, 2000, 1394
+                       // Trading Association, TA Document 1999027)'.
+                       directories[0] = vendor_directory;
+                       directories[1] = root_directory;
+               }
        }

        if (buf) {
@@ -342,8 +346,11 @@ static ssize_t show_text_leaf(struct device *dev,
                bufsize = 1;
        }

-       for (i = 0; i < ARRAY_SIZE(directories) && directories[i]; ++i)
+       for (i = 0; i < ARRAY_SIZE(directories) && directories[i]; ++i) {
                ret = fw_csr_string(directories[i], attr->key, buf, bufsize);
+               if (ret >= 0)
+                       break;
+       }

        if (ret >= 0) {
                /* Strip trailing whitespace and add newline. */
```

Thanks

Takashi Sakamoto