arm: Introduce a generic way to use a device from acpi

Add generic way to use device from acpi similar to the way it is
supported in device tree.

Signed-off-by: Parth Dixit <parth.dixit@linaro.org>
Signed-off-by: Shannon Zhao <shannon.zhao@linaro.org>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

xen/arch/arm/device.c

@@ -22,6 +22,7 @@
 #include <xen/lib.h>
 
 extern const struct device_desc _sdevice[], _edevice[];
+extern const struct acpi_device_desc _asdevice[], _aedevice[];
 
 int __init device_init(struct dt_device_node *dev, enum device_class class,
                        const void *data)
@@ -50,6 +51,23 @@ int __init device_init(struct dt_device_node *dev, enum device_class class,
     return -EBADF;
 }
 
+int __init acpi_device_init(enum device_class class, const void *data, int class_type)
+{
+    const struct acpi_device_desc *desc;
+
+    for ( desc = _asdevice; desc != _aedevice; desc++ )
+    {
+        if ( ( desc->class != class ) || ( desc->class_type != class_type ) )
+            continue;
+
+        ASSERT(desc->init != NULL);
+
+        return desc->init(data);
+    }
+
+    return -EBADF;
+}
+
 enum device_class device_get_class(const struct dt_device_node *dev)
 {
     const struct device_desc *desc;

xen/arch/arm/xen.lds.S

@@ -105,6 +105,13 @@ SECTIONS
       _edevice = .;
   } :text
 
+  . = ALIGN(8);
+  .adev.info : {
+      _asdevice = .;
+      *(.adev.info)
+      _aedevice = .;
+  } :text
+
   . = ALIGN(PAGE_SIZE);             /* Init code and data */
   __init_begin = .;
   .init.text : {

xen/include/asm-arm/device.h

@@ -50,6 +50,27 @@ struct device_desc {
     int (*init)(struct dt_device_node *dev, const void *data);
 };
 
+struct acpi_device_desc {
+    /* Device name */
+    const char *name;
+    /* Device class */
+    enum device_class class;
+    /* type of device supported by the driver */
+    const int class_type;
+    /* Device initialization */
+    int (*init)(const void *data);
+};
+
+/**
+ *  acpi_device_init - Initialize a device
+ *  @class: class of the device (serial, network...)
+ *  @data: specific data for initializing the device
+ *
+ *  Return 0 on success.
+ */
+int __init acpi_device_init(enum device_class class,
+                            const void *data, int class_type);
+
 /**
  *  device_init - Initialize a device
  *  @dev: device to initialize
@@ -78,6 +99,15 @@ __section(".dev.info") = {                                          \
 #define DT_DEVICE_END                                               \
 };
 
+#define ACPI_DEVICE_START(_name, _namestr, _class)                    \
+static const struct acpi_device_desc __dev_desc_##_name __used           \
+__section(".adev.info") = {                       \
+    .name = _namestr,                                               \
+    .class = _class,                                                \
+
+#define ACPI_DEVICE_END                                               \
+};
+
 #endif /* __ASM_ARM_DEVICE_H */
 
 /*