firewire: core: add helper function to handle port status from self ID sequence and its KUnit test

The self ID sequence delivers the information about the state of port.

This commit adds some enumerations to express the state of port, and
some helper functions to handle the state. It adds a KUnit test for them,
too.

Link: https://lore.kernel.org/r/20240605235155.116468-3-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>

2 files changed, 116 insertions, 0 deletions

diff --git a/drivers/firewire/phy-packet-definitions.h b/drivers/firewire/phy-packet-definitions.h
index 479bb3431afb..4ba8b18aa993 100644
--- a/drivers/firewire/phy-packet-definitions.h
+++ b/drivers/firewire/phy-packet-definitions.h
@@ -15,6 +15,8 @@
 #define SELF_ID_EXTENDED_SEQUENCE_MASK			0x00700000
 #define SELF_ID_EXTENDED_SEQUENCE_SHIFT			20
 
+#define SELF_ID_PORT_STATUS_MASK			0x3
+
 #define SELF_ID_SEQUENCE_MAXIMUM_QUADLET_COUNT		4
 
 static inline bool phy_packet_self_id_get_extended(u32 quadlet)
@@ -75,4 +77,45 @@ static inline const u32 *self_id_sequence_enumerator_next(
 	return self_id_sequence;
 }
 
+enum phy_packet_self_id_port_status {
+	PHY_PACKET_SELF_ID_PORT_STATUS_NONE = 0,
+	PHY_PACKET_SELF_ID_PORT_STATUS_NCONN = 1,
+	PHY_PACKET_SELF_ID_PORT_STATUS_PARENT = 2,
+	PHY_PACKET_SELF_ID_PORT_STATUS_CHILD = 3,
+};
+
+static inline unsigned int self_id_sequence_get_port_capacity(unsigned int quadlet_count)
+{
+	return quadlet_count * 8 - 5;
+}
+
+static inline enum phy_packet_self_id_port_status self_id_sequence_get_port_status(
+		const u32 *self_id_sequence, unsigned int quadlet_count, unsigned int port_index)
+{
+	unsigned int index, shift;
+
+	index = (port_index + 5) / 8;
+	shift = 16 - ((port_index + 5) % 8) * 2;
+
+	if (index < quadlet_count && index < SELF_ID_SEQUENCE_MAXIMUM_QUADLET_COUNT)
+		return (self_id_sequence[index] >> shift) & SELF_ID_PORT_STATUS_MASK;
+
+	return PHY_PACKET_SELF_ID_PORT_STATUS_NONE;
+}
+
+static inline void self_id_sequence_set_port_status(u32 *self_id_sequence, unsigned int quadlet_count,
+						    unsigned int port_index,
+						    enum phy_packet_self_id_port_status status)
+{
+	unsigned int index, shift;
+
+	index = (port_index + 5) / 8;
+	shift = 16 - ((port_index + 5) % 8) * 2;
+
+	if (index < quadlet_count) {
+		self_id_sequence[index] &= ~(SELF_ID_PORT_STATUS_MASK << shift);
+		self_id_sequence[index] |= status << shift;
+	}
+}
+
 #endif // _FIREWIRE_PHY_PACKET_DEFINITIONS_H
diff --git a/drivers/firewire/self-id-sequence-helper-test.c b/drivers/firewire/self-id-sequence-helper-test.c
index e8a435e20241..eed7a2294e64 100644
--- a/drivers/firewire/self-id-sequence-helper-test.c
+++ b/drivers/firewire/self-id-sequence-helper-test.c
@@ -63,9 +63,82 @@ static void test_self_id_sequence_enumerator_invalid(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, PTR_ERR(entry), -EPROTO);
 }
 
+static void test_self_id_sequence_get_port_status(struct kunit *test)
+{
+	static const u32 expected[] = {
+		0x000000e5,
+		0x00839e79,
+		0x0091e79d,
+		0x00a279e4,
+	};
+	u32 quadlets [] = {
+		0x00000001,
+		0x00800001,
+		0x00900001,
+		0x00a00000,
+	};
+	enum phy_packet_self_id_port_status port_status[28];
+	unsigned int port_capacity;
+	unsigned int port_index;
+
+	KUNIT_ASSERT_EQ(test, ARRAY_SIZE(expected), ARRAY_SIZE(quadlets));
+
+	// With an extra port.
+	port_capacity = self_id_sequence_get_port_capacity(ARRAY_SIZE(expected)) + 1;
+	KUNIT_ASSERT_EQ(test, port_capacity, ARRAY_SIZE(port_status));
+
+	for (port_index = 0; port_index < port_capacity; ++port_index) {
+		port_status[port_index] =
+			self_id_sequence_get_port_status(expected, ARRAY_SIZE(expected), port_index);
+		self_id_sequence_set_port_status(quadlets, ARRAY_SIZE(quadlets), port_index,
+						 port_status[port_index]);
+	}
+
+	// Self ID zero.
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_CHILD, port_status[0]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_PARENT, port_status[1]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_NCONN, port_status[2]);
+
+	// Self ID one.
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_CHILD, port_status[3]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_PARENT, port_status[4]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_NCONN, port_status[5]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_CHILD, port_status[6]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_PARENT, port_status[7]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_NCONN, port_status[8]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_CHILD, port_status[9]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_PARENT, port_status[10]);
+
+	// Self ID two.
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_NCONN, port_status[11]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_CHILD, port_status[12]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_PARENT, port_status[13]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_NCONN, port_status[14]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_CHILD, port_status[15]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_PARENT, port_status[16]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_NCONN, port_status[17]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_CHILD, port_status[18]);
+
+	// Self ID three.
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_PARENT, port_status[19]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_NCONN, port_status[20]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_CHILD, port_status[21]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_PARENT, port_status[22]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_NCONN, port_status[23]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_CHILD, port_status[24]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_PARENT, port_status[25]);
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_NCONN, port_status[26]);
+
+	// Our of order.
+	KUNIT_EXPECT_EQ(test, PHY_PACKET_SELF_ID_PORT_STATUS_NONE, port_status[27]);
+
+	KUNIT_EXPECT_MEMEQ(test, quadlets, expected, sizeof(expected));
+}
+
 static struct kunit_case self_id_sequence_helper_test_cases[] = {
 	KUNIT_CASE(test_self_id_sequence_enumerator_valid),
 	KUNIT_CASE(test_self_id_sequence_enumerator_invalid),
+	KUNIT_CASE(test_self_id_sequence_get_port_status),
 	{}
 };