[Xen-devel] [PATCH 04/12] arm: parse modules from DT during early boot.

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

The bootloader should populate /chosen/module@<N>/ for each module it
wishes to pass to the hypervisor. The content of these nodes is
described in docs/misc/arm/device-tree/booting.txt

The hypervisor allows for 2 modules (@1==kernel and @2==initrd).
Currently we don't do anything with them.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
v2: Reserve the zeroeth module for Xen itself (not used yet)
    Use a more idiomatic DT layout
    Document said layout
---
 docs/misc/arm/device-tree/booting.txt |   27 ++++++++++++
 xen/common/device_tree.c              |   75 +++++++++++++++++++++++++++++++++
 xen/include/xen/device_tree.h         |   14 ++++++
 3 files changed, 116 insertions(+), 0 deletions(-)
 create mode 100644 docs/misc/arm/device-tree/booting.txt

diff --git a/docs/misc/arm/device-tree/booting.txt 
b/docs/misc/arm/device-tree/booting.txt
new file mode 100644
index 0000000..2609450
--- /dev/null
+++ b/docs/misc/arm/device-tree/booting.txt
@@ -0,0 +1,27 @@
+Xen is passed the dom0 kernel and initrd via a reference in the /chosen
+node of the device tree.
+
+Each node has the form /chosen/module@<N> and contains the following
+properties:
+
+- compatible
+
+       Must be "xen,multiboot-module"
+
+- start
+
+       Physical address of the start of this module
+
+- end
+
+       Physical address of the end of this module
+
+- bootargs (optional)
+
+       Command line associated with this module
+
+The following modules are understood
+
+- 1 -- the domain 0 kernel
+- 2 -- the domain 0 ramdisk
+
diff --git a/xen/common/device_tree.c b/xen/common/device_tree.c
index 3d1f0f4..efd1663 100644
--- a/xen/common/device_tree.c
+++ b/xen/common/device_tree.c
@@ -229,6 +229,79 @@ static void __init process_memory_node(const void *fdt, 
int node,
     }
 }
 
+static void __init process_chosen_node(const void *fdt, int node,
+                                       const char *name,
+                                       u32 address_cells, u32 size_cells)
+{
+    const struct fdt_property *prop;
+    const u32 *cell;
+    paddr_t size;
+    int nr, depth, nr_modules = 0;
+    struct dt_mb_module *mod;
+    int len;
+
+    for ( depth = 0;
+          depth >= 0;
+          node = fdt_next_node(fdt, node, &depth) )
+    {
+        name = fdt_get_name(fdt, node, NULL);
+        if ( strncmp(name, "module@", strlen("module@")) == 0 ) {
+
+            if ( fdt_node_check_compatible(fdt, node,
+                                           "xen,multiboot-module" ) != 0 )
+                early_panic("%s not a compatible module node\n", name);
+
+            nr = simple_strtol(name + strlen("module@"), NULL, 10);
+            if ( nr <= 0 )
+                early_panic("Invalid module number %d\n", nr);
+
+            if ( nr > NR_MODULES )
+                early_panic("too many modules %d > %d\n", nr, NR_MODULES);
+            if ( nr > nr_modules )
+                nr_modules = nr;
+
+            mod = &early_info.modules.module[nr];
+
+            prop = fdt_get_property(fdt, node, "start", NULL);
+            if ( !prop )
+                early_panic("no start for module %d\n", nr);
+
+            cell = (const u32 *)prop->data;
+            device_tree_get_reg(&cell, address_cells, size_cells,
+                                &mod->start, &size);
+
+            prop = fdt_get_property(fdt, node, "end", NULL);
+            if ( !prop )
+                early_panic("no end for module %d\n", nr);
+
+            cell = (const u32 *)prop->data;
+            device_tree_get_reg(&cell, address_cells, size_cells,
+                                &mod->size, &size);
+            mod->size -= mod->start;
+
+            prop = fdt_get_property(fdt, node, "bootargs", &len);
+            if ( prop )
+            {
+                if ( len > sizeof(mod->cmdline) )
+                    early_panic("module %d command line too long\n", nr);
+
+                safe_strcpy(mod->cmdline, prop->data);
+            }
+            else
+                mod->cmdline[0] = 0;
+        }
+    }
+
+    for ( nr = 1 ; nr < nr_modules ; nr++ )
+    {
+        mod = &early_info.modules.module[nr];
+        if ( !mod->start || !mod->size )
+            early_panic("module %d  missing / invalid\n", nr);
+    }
+
+    early_info.modules.nr_mods = nr_modules;
+}
+
 static int __init early_scan_node(const void *fdt,
                                   int node, const char *name, int depth,
                                   u32 address_cells, u32 size_cells,
@@ -236,6 +309,8 @@ static int __init early_scan_node(const void *fdt,
 {
     if ( device_tree_node_matches(fdt, node, "memory") )
         process_memory_node(fdt, node, name, address_cells, size_cells);
+    else if ( device_tree_node_matches(fdt, node, "chosen") )
+        process_chosen_node(fdt, node, name, address_cells, size_cells);
 
     return 0;
 }
diff --git a/xen/include/xen/device_tree.h b/xen/include/xen/device_tree.h
index 4d010c0..c383677 100644
--- a/xen/include/xen/device_tree.h
+++ b/xen/include/xen/device_tree.h
@@ -15,6 +15,7 @@
 #define DEVICE_TREE_MAX_DEPTH 16
 
 #define NR_MEM_BANKS 8
+#define NR_MODULES 2
 
 struct membank {
     paddr_t start;
@@ -26,8 +27,21 @@ struct dt_mem_info {
     struct membank bank[NR_MEM_BANKS];
 };
 
+struct dt_mb_module {
+    paddr_t start;
+    paddr_t size;
+    char cmdline[1024];
+};
+
+struct dt_module_info {
+    int nr_mods;
+    /* Module 0 is Xen itself, followed by the provided modules-proper */
+    struct dt_mb_module module[NR_MODULES + 1];
+};
+
 struct dt_early_info {
     struct dt_mem_info mem;
+    struct dt_module_info modules;
 };
 
 typedef int (*device_tree_node_func)(const void *fdt,
-- 
1.7.9.1


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