dm: core: Add basic ACPI support

ACPI (Advanced Configuration and Power Interface) is a standard for
specifying information about a platform. It is a little like device
tree but the bindings are part of the specification and it supports an
interpreted bytecode language.

Driver model does not use ACPI for U-Boot's configuration, but it is
convenient to have it support generation of ACPI tables for passing to
Linux, etc.

As a starting point, add an optional set of ACPI operations to each
device. Initially only a single operation is available, to obtain the
ACPI name for the device. More operations are added later.

Enable ACPI for sandbox to ensure build coverage and so that we can add
tests.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

configs/tools-only_defconfig

@@ -26,3 +26,4 @@ CONFIG_SYSRESET=y
 # CONFIG_VIRTIO_PCI is not set
 # CONFIG_VIRTIO_SANDBOX is not set
 # CONFIG_EFI_LOADER is not set
+# CONFIG_ACPIGEN is not set

drivers/core/Kconfig

@@ -261,4 +261,13 @@ config DM_DEV_READ_INLINE
 	bool
 	default y if !OF_LIVE
 
+config ACPIGEN
+	bool "Support ACPI table generation in driver model"
+	default y if SANDBOX || GENERATE_ACPI_TABLE
+	help
+	  This option enables generation of ACPI tables using driver-model
+	  devices. It adds a new operation struct to each driver, to support
+	  things like generating device-specific tables and returning the ACPI
+	  name of a device.
+
 endmenu

drivers/core/Makefile

@@ -3,6 +3,7 @@
 # Copyright (c) 2013 Google, Inc
 
 obj-y	+= device.o fdtaddr.o lists.o root.o uclass.o util.o
+obj-$(CONFIG_$(SPL_TPL_)ACPIGEN) += acpi.o
 obj-$(CONFIG_DEVRES) += devres.o
 obj-$(CONFIG_$(SPL_)DM_DEVICE_REMOVE)	+= device-remove.o
 obj-$(CONFIG_$(SPL_)SIMPLE_BUS)	+= simple-bus.o

drivers/core/acpi.c

@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Core driver model support for ACPI table generation
+ *
+ * Copyright 2019 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#define LOG_CATEOGRY	LOGC_ACPI
+
+#include <common.h>
+#include <dm.h>
+#include <dm/acpi.h>
+#include <dm/root.h>
+
+int acpi_copy_name(char *out_name, const char *name)
+{
+	strncpy(out_name, name, ACPI_NAME_LEN);
+	out_name[ACPI_NAME_LEN] = '\0';
+
+	return 0;
+}
+
+int acpi_get_name(const struct udevice *dev, char *out_name)
+{
+	struct acpi_ops *aops;
+
+	aops = device_get_acpi_ops(dev);
+	if (aops && aops->get_name)
+		return aops->get_name(dev, out_name);
+
+	return -ENOSYS;
+}

include/dm/acpi.h

@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Core ACPI (Advanced Configuration and Power Interface) support
+ *
+ * Copyright 2019 Google LLC
+ * Written by Simon Glass <sjg@chromium.org>
+ */
+
+#ifndef __DM_ACPI_H__
+#define __DM_ACPI_H__
+
+/* Allow operations to be optional for ACPI */
+#if CONFIG_IS_ENABLED(ACPIGEN)
+#define ACPI_OPS_PTR(_ptr)	.acpi_ops	= _ptr,
+#else
+#define ACPI_OPS_PTR(_ptr)
+#endif
+
+/* Length of an ACPI name string, excluding nul terminator */
+#define ACPI_NAME_LEN	4
+
+/* Length of an ACPI name string including nul terminator */
+#define ACPI_NAME_MAX	(ACPI_NAME_LEN + 1)
+
+/**
+ * struct acpi_ops - ACPI operations supported by driver model
+ */
+struct acpi_ops {
+	/**
+	 * get_name() - Obtain the ACPI name of a device
+	 *
+	 * @dev: Device to check
+	 * @out_name: Place to put the name, must hold at least ACPI_NAME_MAX
+	 *	bytes
+	 * @return 0 if OK, -ENOENT if no name is available, other -ve value on
+	 *	other error
+	 */
+	int (*get_name)(const struct udevice *dev, char *out_name);
+};
+
+#define device_get_acpi_ops(dev)	((dev)->driver->acpi_ops)
+
+/**
+ * acpi_get_name() - Obtain the ACPI name of a device
+ *
+ * @dev: Device to check
+ * @out_name: Place to put the name, must hold at least ACPI_NAME_MAX
+ *	bytes
+ * @return 0 if OK, -ENOENT if no name is available, other -ve value on
+ *	other error
+ */
+int acpi_get_name(const struct udevice *dev, char *out_name);
+
+/**
+ * acpi_copy_name() - Copy an ACPI name to an output buffer
+ *
+ * This convenience function can be used to return a literal string as a name
+ * in functions that implement the get_name() method.
+ *
+ * For example:
+ *
+ *	static int mydev_get_name(const struct udevice *dev, char *out_name)
+ *	{
+ *		return acpi_copy_name(out_name, "WIBB");
+ *	}
+ *
+ * @out_name: Place to put the name
+ * @name: Name to copy
+ * @return 0 (always)
+ */
+int acpi_copy_name(char *out_name, const char *name);
+
+#endif

include/dm/device.h

@@ -245,6 +245,8 @@ struct udevice_id {
  * pointers defined by the driver, to implement driver functions required by
  * the uclass.
  * @flags: driver flags - see DM_FLAGS_...
+ * @acpi_ops: Advanced Configuration and Power Interface (ACPI) operations,
+ * allowing the device to add things to the ACPI tables passed to Linux
  */
 struct driver {
 	char *name;
@@ -264,6 +266,9 @@ struct driver {
 	int per_child_platdata_auto_alloc_size;
 	const void *ops;	/* driver-specific operations */
 	uint32_t flags;
+#if CONFIG_IS_ENABLED(ACPIGEN)
+	struct acpi_ops *acpi_ops;
+#endif
 };
 
 /* Declare a new U-Boot driver */

include/log.h

@@ -51,6 +51,8 @@ enum log_category_t {
 	LOGC_SANDBOX,	/* Related to the sandbox board */
 	LOGC_BLOBLIST,	/* Bloblist */
 	LOGC_DEVRES,	/* Device resources (devres_... functions) */
+	/* Advanced Configuration and Power Interface (ACPI) */
+	LOGC_ACPI,
 
 	LOGC_COUNT,	/* Number of log categories */
 	LOGC_END,	/* Sentinel value for a list of log categories */