--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ARM APMT table support.
+ * Design document number: ARM DEN0117.
+ *
+ * Copyright (c) 2022, NVIDIA CORPORATION & AFFILIATES.
+ *
+ */
+
+#define pr_fmt(fmt) "ACPI: APMT: " fmt
+
+#include <linux/acpi.h>
+#include <linux/acpi_apmt.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+
+#define DEV_NAME "arm-cs-arch-pmu"
+
+/* There can be up to 3 resources: page 0 and 1 address, and interrupt. */
+#define DEV_MAX_RESOURCE_COUNT 3
+
+/* Root pointer to the mapped APMT table */
+static struct acpi_table_header *apmt_table;
+
+static int __init apmt_init_resources(struct resource *res,
+ struct acpi_apmt_node *node)
+{
+ int irq, trigger;
+ int num_res = 0;
+
+ res[num_res].start = node->base_address0;
+ res[num_res].end = node->base_address0 + SZ_4K - 1;
+ res[num_res].flags = IORESOURCE_MEM;
+
+ num_res++;
+
+ res[num_res].start = node->base_address1;
+ res[num_res].end = node->base_address1 + SZ_4K - 1;
+ res[num_res].flags = IORESOURCE_MEM;
+
+ num_res++;
+
+ if (node->ovflw_irq != 0) {
+ trigger = (node->ovflw_irq_flags & ACPI_APMT_OVFLW_IRQ_FLAGS_MODE);
+ trigger = (trigger == ACPI_APMT_OVFLW_IRQ_FLAGS_MODE_LEVEL) ?
+ ACPI_LEVEL_SENSITIVE : ACPI_EDGE_SENSITIVE;
+ irq = acpi_register_gsi(NULL, node->ovflw_irq, trigger,
+ ACPI_ACTIVE_HIGH);
+
+ if (irq <= 0) {
+ pr_warn("APMT could not register gsi hwirq %d\n", irq);
+ return num_res;
+ }
+
+ res[num_res].start = irq;
+ res[num_res].end = irq;
+ res[num_res].flags = IORESOURCE_IRQ;
+
+ num_res++;
+ }
+
+ return num_res;
+}
+
+/**
+ * apmt_add_platform_device() - Allocate a platform device for APMT node
+ * @node: Pointer to device ACPI APMT node
+ *
+ * Returns: 0 on success, <0 failure
+ */
+static int __init apmt_add_platform_device(struct acpi_apmt_node *node,
+ struct fwnode_handle *fwnode)
+{
+ struct platform_device *pdev;
+ int ret, count;
+ struct resource res[DEV_MAX_RESOURCE_COUNT];
+
+ pdev = platform_device_alloc(DEV_NAME, PLATFORM_DEVID_AUTO);
+ if (!pdev)
+ return -ENOMEM;
+
+ memset(res, 0, sizeof(res));
+
+ count = apmt_init_resources(res, node);
+
+ ret = platform_device_add_resources(pdev, res, count);
+ if (ret)
+ goto dev_put;
+
+ /*
+ * Add a copy of APMT node pointer to platform_data to be used to
+ * retrieve APMT data information.
+ */
+ ret = platform_device_add_data(pdev, &node, sizeof(node));
+ if (ret)
+ goto dev_put;
+
+ pdev->dev.fwnode = fwnode;
+
+ ret = platform_device_add(pdev);
+
+ if (ret)
+ goto dev_put;
+
+ return 0;
+
+dev_put:
+ platform_device_put(pdev);
+
+ return ret;
+}
+
+static int __init apmt_init_platform_devices(void)
+{
+ struct acpi_apmt_node *apmt_node;
+ struct acpi_table_apmt *apmt;
+ struct fwnode_handle *fwnode;
+ u64 offset, end;
+ int ret;
+
+ /*
+ * apmt_table and apmt both point to the start of APMT table, but
+ * have different struct types
+ */
+ apmt = (struct acpi_table_apmt *)apmt_table;
+ offset = sizeof(*apmt);
+ end = apmt->header.length;
+
+ while (offset < end) {
+ apmt_node = ACPI_ADD_PTR(struct acpi_apmt_node, apmt,
+ offset);
+
+ fwnode = acpi_alloc_fwnode_static();
+ if (!fwnode)
+ return -ENOMEM;
+
+ ret = apmt_add_platform_device(apmt_node, fwnode);
+ if (ret) {
+ acpi_free_fwnode_static(fwnode);
+ return ret;
+ }
+
+ offset += apmt_node->length;
+ }
+
+ return 0;
+}
+
+void __init acpi_apmt_init(void)
+{
+ acpi_status status;
+ int ret;
+
+ /**
+ * APMT table nodes will be used at runtime after the apmt init,
+ * so we don't need to call acpi_put_table() to release
+ * the APMT table mapping.
+ */
+ status = acpi_get_table(ACPI_SIG_APMT, 0, &apmt_table);
+
+ if (ACPI_FAILURE(status)) {
+ if (status != AE_NOT_FOUND) {
+ const char *msg = acpi_format_exception(status);
+
+ pr_err("Failed to get APMT table, %s\n", msg);
+ }
+
+ return;
+ }
+
+ ret = apmt_init_platform_devices();
+ if (ret) {
+ pr_err("Failed to initialize APMT platform devices, ret: %d\n", ret);
+ acpi_put_table(apmt_table);
+ }
+}
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