platform: generic: Tenstorrent Atlantis support

Add the Tenstorrent Atlantis as a generic-platform. This initial support
enables the single_fw_region option, and verifies and prints HART PMA
CSR configuration.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20260424062520.238403-1-npiggin@gmail.com
Signed-off-by: Anup Patel <anup@brainfault.org>

platform/generic/tenstorrent/Kconfig

@@ -0,0 +1,5 @@
+# SPDX-FileCopyrightText: (c) 2025-2026 Tenstorrent USA, Inc.
+# SPDX-License-Identifier: BSD-2-Clause
+
+config CPU_TENSTORRENT_ASCALON
+	bool

platform/generic/tenstorrent/ascalon.c

@@ -0,0 +1,53 @@
+/*
+ * SPDX-FileCopyrightText: (c) 2025-2026 Tenstorrent USA, Inc.
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <sbi/riscv_asm.h>
+#include <sbi/sbi_console.h>
+#include <sbi/sbi_csr_detect.h>
+
+#include <tenstorrent/ascalon.h>
+#include <tenstorrent/pma.h>
+
+#define CSR_PMACFG0	0x7e0
+
+void tt_ascalon_discover_pmas_from_boot_hart(void)
+{
+	struct sbi_trap_info trap = {0};
+
+	/* Whisper virtual platform does not implement PMA */
+	csr_read_allowed(CSR_PMACFG0, &trap);
+	if (trap.cause)
+		return;
+
+	for (unsigned int i = 0; i < TT_MAX_PMAS; i++) {
+		u64 pma = csr_read_num(CSR_PMACFG0 + i);
+		if (!tt_pma_validate(i, pma)) {
+			sbi_printf("HART%d: Bad boot PMA%02d 0x%016lx\n",
+				   current_hartid(), i, pma);
+		}
+		tt_pma_set(i, pma);
+
+		if (pma)
+			tt_pma_print(i, pma);
+	}
+}
+
+void tt_ascalon_verify_pmas_nonboot_hart(void)
+{
+	struct sbi_trap_info trap = {0};
+
+	/* Whisper virtual platform does not implement PMA */
+	csr_read_allowed(CSR_PMACFG0, &trap);
+	if (trap.cause)
+		return;
+
+	for (unsigned int i = 0; i < TT_MAX_PMAS; i++) {
+		u64 pma = csr_read_num(CSR_PMACFG0 + i);
+		if (pma != tt_pma_get(i)) {
+			sbi_printf("HART%d: Bad boot PMA%02d 0x%016lx does not match boot HART\n",
+				   current_hartid(), i, pma);
+		}
+	}
+}

platform/generic/tenstorrent/atlantis.c

@@ -0,0 +1,50 @@
+/*
+ * SPDX-FileCopyrightText: (c) 2025-2026 Tenstorrent USA, Inc.
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <platform_override.h>
+#include <libfdt.h>
+#include <sbi/sbi_error.h>
+#include <sbi/sbi_hart.h>
+#include <sbi/sbi_system.h>
+#include <sbi/sbi_console.h>
+
+#include <tenstorrent/ascalon.h>
+#include <tenstorrent/pma.h>
+
+static int tt_atlantis_final_init(bool cold_boot)
+{
+	if (cold_boot) {
+		/* Boot firmware sets HART PMAs. Read and verify them. */
+		tt_ascalon_discover_pmas_from_boot_hart();
+	} else {
+		/* Verify nonboot HARTs have PMAs matching boot HART */
+		tt_ascalon_verify_pmas_nonboot_hart();
+	}
+
+	return generic_final_init(cold_boot);
+}
+
+static bool tt_atlantis_single_fw_region(void)
+{
+	return true;
+}
+
+static int tt_atlantis_platform_init(const void *fdt, int nodeoff, const struct fdt_match *match)
+{
+	generic_platform_ops.final_init = tt_atlantis_final_init;
+	generic_platform_ops.single_fw_region = tt_atlantis_single_fw_region;
+
+	return 0;
+}
+
+static const struct fdt_match tt_atlantis_match[] = {
+	{ .compatible = "tenstorrent,atlantis" },
+	{ },
+};
+
+const struct fdt_driver tenstorrent_atlantis = {
+	.match_table = tt_atlantis_match,
+	.init = tt_atlantis_platform_init,
+};

platform/generic/tenstorrent/objects.mk

@@ -0,0 +1,12 @@
+#
+# SPDX-FileCopyrightText: (c) 2025-2026 Tenstorrent USA, Inc.
+# SPDX-License-Identifier: BSD-2-Clause
+#
+
+ifeq ($(PLATFORM_RISCV_XLEN), 64)
+platform-objs-y += tenstorrent/pma.o
+platform-objs-$(CONFIG_CPU_TENSTORRENT_ASCALON) += tenstorrent/ascalon.o
+
+carray-platform_override_modules-$(CONFIG_PLATFORM_TENSTORRENT_ATLANTIS) += tenstorrent_atlantis
+platform-objs-$(CONFIG_PLATFORM_TENSTORRENT_ATLANTIS) += tenstorrent/atlantis.o
+endif

platform/generic/tenstorrent/pma.c

@@ -0,0 +1,138 @@
+/*
+ * SPDX-FileCopyrightText: (c) 2025-2026 Tenstorrent USA, Inc.
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <sbi/sbi_error.h>
+#include <sbi/sbi_console.h>
+#include <sbi/sbi_math.h>
+#include <libfdt.h>
+#include <sbi_utils/fdt/fdt_helper.h>
+
+#include <tenstorrent/pma.h>
+
+/*
+ * All PMAs in the system should be the same (after boot). The init code
+ * must have set PMAs for all HARTs.
+ */
+
+/*
+ * Ascalon CPU and IOMMU PMA layout:
+ * Field
+ * [2:0]	Permission	[0] Read, [1] Write, [2] Execute
+ * [4:3]	Memory type	00: Main memory, 01: IO memory relaxed,
+ * 				10: IO memory channel 0, 11: IO memory channel 1
+ * [6:5]	AMO type	00: AMONone, 01: AMOSwap,
+ * 				10: AMOLogical, 11: AMOArithmetic
+ * [7]		Cacheability (main memory type)
+ * 				1: Cacheable, 0: Non-cacheable
+ * 		Combining Capability (IO memory type)
+ * 				1: Combining allowed, 0: Combining disallowed
+ * [8]		Routing (coherency)
+ * 				1: Coherent network, 0: Non-coherent network
+ * [11:9]	Reserved
+ * [51:12]	Physical address [51:12] base
+ * [63:58]	Size log 2 (number of address LSB to ignore when matching)
+ * 		0 = invalid entry (no match)
+ */
+
+#define PMA_PERMISSION_R	0x1
+#define PMA_PERMISSION_W	0x2
+#define PMA_PERMISSION_X	0x4
+#define PMA_PERMISSION_MASK	0x7
+
+#define PMA_TYPE_MAIN_MEMORY	0x0
+#define PMA_TYPE_IO_RELAXED	0x8
+#define PMA_TYPE_IO_ORDERED_0	0x10
+#define PMA_TYPE_IO_ORDERED_1	0x18
+#define PMA_TYPE_MASK		0x18
+
+#define PMA_AMO_NONE		0x0
+#define PMA_AMO_SWAP		0x20
+#define PMA_AMO_LOGICAL		0x40
+#define PMA_AMO_ARITHMETIC	0x60
+#define PMA_AMO_MASK		0x60
+
+#define PMA_MEMORY_CACHEABLE	0x80
+#define PMA_IO_COMBINING	0x80
+#define PMA_ROUTING_COHERENT	0x100
+
+#define PMA_FLAGS_MASK		0x00000000000001ffULL
+#define PMA_ADDRESS_MASK	0x000ffffffffff000ULL
+#define PMA_SIZE_MASK		0xfc00000000000000ULL
+#define PMA_RESERVED_MASK	0x0300000000000e00ULL
+
+#define PMA_SIZE_SHIFT		58
+
+static u64 tt_pma_size(u64 pma)
+{
+	if ((pma & PMA_SIZE_MASK) == 0)
+		return 0;
+
+	return 1ULL << ((pma & PMA_SIZE_MASK) >> PMA_SIZE_SHIFT);
+}
+
+static u64 tt_pma_address(u64 pma)
+{
+	return (pma & PMA_ADDRESS_MASK) & ~((tt_pma_size(pma) - 1));
+}
+
+bool tt_pma_validate(unsigned int i, u64 pma)
+{
+	if (!pma)
+		return true;
+
+	if (pma & PMA_RESERVED_MASK) {
+		sbi_printf("PMA%02u 0x%016lx contains reserved bits\n", i, pma);
+		return false;
+	}
+
+	if (tt_pma_size(pma) < 4096) {
+		sbi_printf("PMA%02u 0x%016lx size < 4KB\n", i, pma);
+		return false;
+	}
+
+	if (tt_pma_address(pma) != (pma & PMA_ADDRESS_MASK)) {
+		sbi_printf("PMA%02u 0x%016lx address is not aligned to size\n", i, pma);
+		return false;
+	}
+
+	return true;
+}
+
+void tt_pma_print(unsigned int i, u64 pma)
+{
+	sbi_printf("PMA%02d                       : 0x%016lx-0x%016lx perm:%s%s%s type:%s %s %s amo:%s\n", i,
+			tt_pma_address(pma), tt_pma_address(pma) + tt_pma_size(pma) - 1,
+			pma & PMA_PERMISSION_R ? "R" : " ",
+			pma & PMA_PERMISSION_W ? "W" : " ",
+			pma & PMA_PERMISSION_X ? "X" : " ",
+			(pma & PMA_TYPE_MASK) == PMA_TYPE_MAIN_MEMORY ? "main-memory" :
+			 ((pma & PMA_TYPE_MASK) == PMA_TYPE_IO_RELAXED ? "io-relaxed" :
+			  ((pma & PMA_TYPE_MASK) == PMA_TYPE_IO_ORDERED_0 ? "io-ordered-0" : "io-ordered-1")),
+			(pma & PMA_TYPE_MASK) == PMA_TYPE_MAIN_MEMORY ?
+			 (pma & PMA_MEMORY_CACHEABLE ? "cacheable" : "non-cacheable") :
+			 (pma & PMA_IO_COMBINING ? "combining" : "non-combining"),
+			pma & PMA_ROUTING_COHERENT ? "coherent" : "non-coherent",
+			(pma & PMA_AMO_MASK) == PMA_AMO_NONE ? "none" :
+			 ((pma & PMA_AMO_MASK) == PMA_AMO_SWAP ? "swap" :
+			  ((pma & PMA_AMO_MASK) == PMA_AMO_LOGICAL ? "logical" : "arithmetic")));
+}
+
+static u64 pmas[TT_MAX_PMAS];
+
+void tt_pma_set(unsigned int n, u64 pma)
+{
+	if (n >= TT_MAX_PMAS)
+		sbi_panic("PMA exceeded TT_MAX_PMAS");
+
+	pmas[n] = pma;
+}
+
+u64 tt_pma_get(unsigned int n)
+{
+	if (n >= TT_MAX_PMAS)
+		sbi_panic("PMA exceeded TT_MAX_PMAS");
+
+	return pmas[n];
+}