[PATCH v2 3/3] misc: open-dice: add ACPI device discovery support

[Song Guo <songguo@google.com>]

OpenDICE can also used on x86 platforms for attestation, one of the
usecase is Android's protected VM.

The OpenDICE device driver only supports device tree, adding ACPI
support so it can also be used on x86 environments easily.

The patch is verified using crosvm, with the following ACPI table passed
using --acpi-table, with --file-backed-mapping for the corresponding
memory region.

DefinitionBlock (
    "opendice.aml", "SSDT", 2, "GOOGLE", "OpenDICE", 0x00000001
)
{
    Scope (\_SB)
    {
        Device (DICE)
        {
            Name (_HID, "PRP0001")

            Name (_DSD, Package () {
                ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
                Package () {
                    Package () {
                        "compatible",
                        Package () { "google,open-dice" }
                    }
                }
            })

            Name (_CRS, ResourceTemplate () {
                Memory32Fixed (ReadOnly, 0x9D1C3000, 0x00001000)
            })
        }
    }
}

Signed-off-by: Song Guo <songguo@google.com>
---
 drivers/misc/open-dice.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/misc/open-dice.c b/drivers/misc/open-dice.c
index aabece6ed3d1..303b35b03cb4 100644
--- a/drivers/misc/open-dice.c
+++ b/drivers/misc/open-dice.c
@@ -2,6 +2,7 @@
 /*
  * Copyright (C) 2021 - Google LLC
  * Author: David Brazdil <dbrazdil@google.com>
+ * Author: Song Guo <songguo@google.com>
  *
  * Driver for Open Profile for DICE.
  *
@@ -19,6 +20,7 @@
  *     close(fd);
  */
 
+#include <linux/acpi.h>
 #include <linux/io.h>
 #include <linux/miscdevice.h>
 #include <linux/mm.h>
@@ -133,8 +135,17 @@ static int __init open_dice_probe(struct platform_device *pdev)
 		}
 		mem_base = rmem->base;
 		mem_size = rmem->size;
+	} else if (is_acpi_node(dev->fwnode)) {
+		struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+		if (!res) {
+			dev_err(dev, "failed to get MMIO resource\n");
+			return -EINVAL;
+		}
+		mem_base = res->start;
+		mem_size = resource_size(res);
 	} else {
-		dev_err(dev, "device not supported (no DT node)\n");
+		dev_err(dev, "device not supported (no DT or ACPI node)\n");
 		return -EINVAL;
 	}
 
@@ -218,3 +229,4 @@ module_exit(open_dice_exit);
 MODULE_DESCRIPTION("Driver for Open Profile for DICE.");
 MODULE_LICENSE("GPL v2");
 MODULE_AUTHOR("David Brazdil <dbrazdil@google.com>");
+MODULE_AUTHOR("Song Guo <songguo@google.com>");
-- 
2.55.0.141.g00534a21ce-goog