soc/tegra: fuse: Add tegra_acpi_init_apbmisc()

In preparation to ACPI support in Tegra fuse driver add function
tegra_acpi_init_apbmisc() to initialize tegra-apbmisc driver.
Also, document the reason of calling tegra_init_apbmisc() at early init.

Note that function tegra_acpi_init_apbmisc() is not placed in the __init
section, because it will be called during probe.
Signed-off-by: Kartik <kkartik@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/soc/tegra/fuse/fuse.h

@@ -69,6 +69,7 @@ struct tegra_fuse {
 
 void tegra_init_revision(void);
 void tegra_init_apbmisc(void);
+void tegra_acpi_init_apbmisc(void);
 
 u32 __init tegra_fuse_read_spare(unsigned int spare);
 u32 __init tegra_fuse_read_early(unsigned int offset);

drivers/soc/tegra/fuse/tegra-apbmisc.c

@@ -3,9 +3,11 @@
  * Copyright (c) 2014-2023, NVIDIA CORPORATION.  All rights reserved.
  */
 
+#include <linux/acpi.h>
 #include <linux/export.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 
@@ -180,6 +182,12 @@ static void tegra_init_apbmisc_resources(struct resource *apbmisc,
 	}
 }
 
+/**
+ * tegra_init_apbmisc - Initializes Tegra APBMISC and Strapping registers.
+ *
+ * This is called during early init as some of the old 32-bit ARM code needs
+ * information from the APBMISC registers very early during boot.
+ */
 void __init tegra_init_apbmisc(void)
 {
 	struct resource apbmisc, straps;
@@ -244,3 +252,67 @@ void __init tegra_init_apbmisc(void)
 put:
 	of_node_put(np);
 }
+
+#ifdef CONFIG_ACPI
+static const struct acpi_device_id apbmisc_acpi_match[] = {
+	{ "NVDA2010" },
+	{ /* sentinel */ }
+};
+
+void tegra_acpi_init_apbmisc(void)
+{
+	struct resource *resources[2] = { NULL };
+	struct resource_entry *rentry;
+	struct acpi_device *adev = NULL;
+	struct list_head resource_list;
+	int rcount = 0;
+	int ret;
+
+	adev = acpi_dev_get_first_match_dev(apbmisc_acpi_match[0].id, NULL, -1);
+	if (!adev)
+		return;
+
+	INIT_LIST_HEAD(&resource_list);
+
+	ret = acpi_dev_get_memory_resources(adev, &resource_list);
+	if (ret < 0) {
+		pr_err("failed to get APBMISC memory resources");
+		goto out_put_acpi_dev;
+	}
+
+	/*
+	 * Get required memory resources.
+	 *
+	 * resources[0]: apbmisc.
+	 * resources[1]: straps.
+	 */
+	resource_list_for_each_entry(rentry, &resource_list) {
+		if (rcount >= ARRAY_SIZE(resources))
+			break;
+
+		resources[rcount++] = rentry->res;
+	}
+
+	if (!resources[0]) {
+		pr_err("failed to get APBMISC registers\n");
+		goto out_free_resource_list;
+	}
+
+	if (!resources[1]) {
+		pr_err("failed to get strapping options registers\n");
+		goto out_free_resource_list;
+	}
+
+	tegra_init_apbmisc_resources(resources[0], resources[1]);
+
+out_free_resource_list:
+	acpi_dev_free_resource_list(&resource_list);
+
+out_put_acpi_dev:
+	acpi_dev_put(adev);
+}
+#else
+void tegra_acpi_init_apbmisc(void)
+{
+}
+#endif