xen/arm: Introduce a generic way to describe device

Currently, Xen is supporting PCI and Platform device (based on Device Tree).

While Xen only supports Platform device on ARM, Xen will gain support of
PCI soon.

Some drivers, such as IOMMU drivers, may handle PCI and platform device in
the same way. Only few lines of code differs.

Rather than requesting to provide 2 set of functions (one for PCI and
one for platform device), introduce a generic structure "device" which
is embedded in each specialized device.

As x86 only supports PCI, introduce a new type device_t which will be an
alias to pci_dev for this architecture. It will avoid to add a new field
for this place.

Signed-off-by: Julien Grall <julien.grall@linaro.org>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
CC: Keir Fraser <keir@xen.org>
CC: Andrew Cooper <andrew.cooper3@citrix.com>

xen/common/device_tree.c

@@ -1454,6 +1454,9 @@ static unsigned long __init unflatten_dt_node(const void *fdt,
             ((char *)pp->value)[sz - 1] = 0;
             dt_dprintk("fixed up name for %s -> %s\n", pathp,
                        (char *)pp->value);
+            /* Generic device initialization */
+            np->dev.type = DEV_DT;
+            np->dev.of_node = np;
         }
     }
     if ( allnextpp )

xen/include/asm-arm/device.h

@@ -2,8 +2,34 @@
 #define __ASM_ARM_DEVICE_H
 
 #include <xen/init.h>
+
+enum device_type
+{
+    DEV_DT,
+};
+
+struct dev_archdata {
+    void *iommu;    /* IOMMU private data */
+};
+
+/* struct device - The basic device structure */
+struct device
+{
+    enum device_type type;
+#ifdef HAS_DEVICE_TREE
+    struct dt_device_node *of_node; /* Used by drivers imported from Linux */
+#endif
+    struct dev_archdata archdata;
+};
+
+typedef struct device device_t;
+
 #include <xen/device_tree.h>
 
+/* TODO: Correctly implement dev_is_pci when PCI is supported on ARM */
+#define dev_is_pci(dev) ((void)(dev), 0)
+#define dev_is_dt(dev)  ((dev->type == DEV_DT)
+
 enum device_class
 {
     DEVICE_SERIAL,

xen/include/asm-x86/device.h

@@ -0,0 +1,25 @@
+#ifndef __ASM_X86_DEVICE_H
+#define __ASM_X86_DEVICE_H
+
+#include <xen/pci.h>
+
+/*
+ * x86 only supports PCI. Therefore it's possible to directly use
+ * pci_dev to avoid adding new field.
+ */
+
+typedef struct pci_dev device_t;
+
+#define dev_is_pci(dev) ((void)(dev), 1)
+#define pci_to_dev(pci) (pci)
+
+#endif /* __ASM_X86_DEVICE_H */
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */

xen/include/xen/device_tree.h

@@ -11,7 +11,9 @@
 #define __XEN_DEVICE_TREE_H__
 
 #include <asm/byteorder.h>
+#include <asm/device.h>
 #include <public/xen.h>
+#include <xen/kernel.h>
 #include <xen/init.h>
 #include <xen/string.h>
 #include <xen/types.h>
@@ -80,8 +82,19 @@ struct dt_device_node {
     /* IOMMU specific fields */
     bool is_protected;
     struct list_head domain_list;
+
+    struct device dev;
 };
 
+#define dt_to_dev(dt_node)  (&(dt_node)->dev)
+
+static inline struct dt_device_node *dev_to_dt(struct device *dev)
+{
+    ASSERT(dev->type == DEV_DT);
+
+    return container_of(dev, struct dt_device_node, dev);
+}
+
 #define MAX_PHANDLE_ARGS 16
 struct dt_phandle_args {
     struct dt_device_node *np;

xen/include/xen/iommu.h

@@ -25,6 +25,7 @@
 #include <xen/pci.h>
 #include <public/hvm/ioreq.h>
 #include <public/domctl.h>
+#include <asm/device.h>
 #include <asm/iommu.h>
 
 extern bool_t iommu_enable, iommu_enabled;

xen/include/xen/pci.h

@@ -13,6 +13,7 @@
 #include <xen/irq.h>
 #include <xen/pci_regs.h>
 #include <xen/pfn.h>
+#include <asm/device.h>
 #include <asm/pci.h>
 
 /*