1 files changed, 133 insertions, 0 deletions
diff --git a/drivers/ras/amd/atl/access.c b/drivers/ras/amd/atl/access.c
new file mode 100644
index 000000000000..ee4661ed28ba
--- /dev/null
+++ b/drivers/ras/amd/atl/access.c
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * AMD Address Translation Library
+ *
+ * access.c : DF Indirect Access functions
+ *
+ * Copyright (c) 2023, Advanced Micro Devices, Inc.
+ * All Rights Reserved.
+ *
+ * Author: Yazen Ghannam <Yazen.Ghannam@amd.com>
+ */
+
+#include "internal.h"
+
+/* Protect the PCI config register pairs used for DF indirect access. */
+static DEFINE_MUTEX(df_indirect_mutex);
+
+/*
+ * Data Fabric Indirect Access uses FICAA/FICAD.
+ *
+ * Fabric Indirect Configuration Access Address (FICAA): constructed based
+ * on the device's Instance Id and the PCI function and register offset of
+ * the desired register.
+ *
+ * Fabric Indirect Configuration Access Data (FICAD): there are FICAD
+ * low and high registers but so far only the low register is needed.
+ *
+ * Use Instance Id 0xFF to indicate a broadcast read.
+ */
+#define DF_BROADCAST		0xFF
+
+#define DF_FICAA_INST_EN	BIT(0)
+#define DF_FICAA_REG_NUM	GENMASK(10, 1)
+#define DF_FICAA_FUNC_NUM	GENMASK(13, 11)
+#define DF_FICAA_INST_ID	GENMASK(23, 16)
+
+#define DF_FICAA_REG_NUM_LEGACY	GENMASK(10, 2)
+
+static u16 get_accessible_node(u16 node)
+{
+	/*
+	 * On heterogeneous systems, not all AMD Nodes are accessible
+	 * through software-visible registers. The Node ID needs to be
+	 * adjusted for register accesses. But its value should not be
+	 * changed for the translation methods.
+	 */
+	if (df_cfg.flags.heterogeneous) {
+		/* Only Node 0 is accessible on DF3.5 systems. */
+		if (df_cfg.rev == DF3p5)
+			node = 0;
+
+		/*
+		 * Only the first Node in each Socket is accessible on
+		 * DF4.5 systems, and this is visible to software as one
+		 * Fabric per Socket.  The Socket ID can be derived from
+		 * the Node ID and global shift values.
+		 */
+		if (df_cfg.rev == DF4p5)
+			node >>= df_cfg.socket_id_shift - df_cfg.node_id_shift;
+	}
+
+	return node;
+}
+
+static int __df_indirect_read(u16 node, u8 func, u16 reg, u8 instance_id, u32 *lo)
+{
+	u32 ficaa_addr = 0x8C, ficad_addr = 0xB8;
+	struct pci_dev *F4;
+	int err = -ENODEV;
+	u32 ficaa = 0;
+
+	node = get_accessible_node(node);
+	if (node >= amd_nb_num())
+		goto out;
+
+	F4 = node_to_amd_nb(node)->link;
+	if (!F4)
+		goto out;
+
+	/* Enable instance-specific access. */
+	if (instance_id != DF_BROADCAST) {
+		ficaa |= FIELD_PREP(DF_FICAA_INST_EN, 1);
+		ficaa |= FIELD_PREP(DF_FICAA_INST_ID, instance_id);
+	}
+
+	/*
+	 * The two least-significant bits are masked when inputing the
+	 * register offset to FICAA.
+	 */
+	reg >>= 2;
+
+	if (df_cfg.flags.legacy_ficaa) {
+		ficaa_addr = 0x5C;
+		ficad_addr = 0x98;
+
+		ficaa |= FIELD_PREP(DF_FICAA_REG_NUM_LEGACY, reg);
+	} else {
+		ficaa |= FIELD_PREP(DF_FICAA_REG_NUM, reg);
+	}
+
+	ficaa |= FIELD_PREP(DF_FICAA_FUNC_NUM, func);
+
+	mutex_lock(&df_indirect_mutex);
+
+	err = pci_write_config_dword(F4, ficaa_addr, ficaa);
+	if (err) {
+		pr_warn("Error writing DF Indirect FICAA, FICAA=0x%x\n", ficaa);
+		goto out_unlock;
+	}
+
+	err = pci_read_config_dword(F4, ficad_addr, lo);
+	if (err)
+		pr_warn("Error reading DF Indirect FICAD LO, FICAA=0x%x.\n", ficaa);
+
+	pr_debug("node=%u inst=0x%x func=0x%x reg=0x%x val=0x%x",
+		 node, instance_id, func, reg << 2, *lo);
+
+out_unlock:
+	mutex_unlock(&df_indirect_mutex);
+
+out:
+	return err;
+}
+
+int df_indirect_read_instance(u16 node, u8 func, u16 reg, u8 instance_id, u32 *lo)
+{
+	return __df_indirect_read(node, func, reg, instance_id, lo);
+}
+
+int df_indirect_read_broadcast(u16 node, u8 func, u16 reg, u32 *lo)
+{
+	return __df_indirect_read(node, func, reg, DF_BROADCAST, lo);
+}