[Qemu-devel] [RESEND RFC 5/6] hw/arm/sysbus-fdt: helpers for clock node generation

[Eric Auger <eric.auger@linaro.org>]

Some passthrough'ed devices depend on clock nodes. Those need to be
generated in the guest device tree. This patch introduces some helpers
to build a clock node from information retrieved from host device tree.

- inherit_properties copies properties from a host device tree node to
  a guest device tree node
- fdt_build_clock_node builds a guest clock node and checks the host
  fellow clock is a fixed one.

fdt_build_clock_node will become static as soon as a they get used

Signed-off-by: Eric Auger <eric.auger@linaro.org>
---
 hw/arm/sysbus-fdt.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)

diff --git a/hw/arm/sysbus-fdt.c b/hw/arm/sysbus-fdt.c
index 9d28797..22e5801 100644
--- a/hw/arm/sysbus-fdt.c
+++ b/hw/arm/sysbus-fdt.c
@@ -21,6 +21,7 @@
  *
  */
 
+#include <libfdt.h>
 #include "hw/arm/sysbus-fdt.h"
 #include "qemu/error-report.h"
 #include "sysemu/device_tree.h"
@@ -56,6 +57,115 @@ typedef struct NodeCreationPair {
     int (*add_fdt_node_fn)(SysBusDevice *sbdev, void *opaque);
 } NodeCreationPair;
 
+/* helpers */
+
+struct HostProperty {
+    const char *name;
+    bool optional;
+};
+
+typedef struct HostProperty HostProperty;
+
+/**
+ * inherit_properties
+ *
+ * copies properties listed in an array from host device tree to
+ * guest device tree. If a non optional property is not found, the
+ * function exits. Not found optional ones are ignored.
+ * props: array of HostProperty to copy
+ * nb_props: number of properties in the array
+ * host_dt: host device tree blob
+ * guest_dt: guest device tree blob
+ * node_path: host dt node path where the property is supposed to be
+              found
+ * nodename: guest node name the properties should be added to
+ *
+ */
+static void inherit_properties(HostProperty *props, int nb_props,
+                               void *host_fdt, void *guest_fdt,
+                               char *node_path, char *nodename)
+{
+    int i, prop_len;
+    const void *r;
+
+    for (i = 0; i < nb_props; i++) {
+        r = qemu_fdt_getprop_optional(host_fdt, node_path,
+                             props[i].name,
+                             props[i].optional,
+                             &prop_len);
+        if (r) {
+            qemu_fdt_setprop(guest_fdt, nodename,
+                             props[i].name, r, prop_len);
+        }
+    }
+}
+
+/* clock properties whose values are copied/pasted from host */
+static HostProperty clock_inherited_properties[] = {
+    {"compatible", 0},
+    {"#clock-cells", 0},
+    {"clock-frequency", 1},
+    {"clock-output-names", 1},
+};
+
+/**
+ * fdt_build_clock_node
+ *
+ * Build a guest clock node, used as a dependency from a passthrough'ed
+ * device. Most information are retrieved from the host fellow node.
+ * Also check the host clock is a fixed one.
+ *
+ * host_fdt: host device tree blob from which info are retrieved
+ * guest_fdt: guest device tree blob where the clock node is added
+ * host_phandle: phandle of the clock in host device tree
+ * guest_phandle: phandle to assign to the guest node
+ */
+int fdt_build_clock_node(void *host_fdt, void *guest_fdt,
+                                uint32_t host_phandle,
+                                uint32_t guest_phandle);
+int fdt_build_clock_node(void *host_fdt, void *guest_fdt,
+                                uint32_t host_phandle,
+                                uint32_t guest_phandle)
+{
+    char node_path[256];
+    char *nodename;
+    const void *r;
+    int ret, prop_len;
+
+    ret = fdt_node_offset_by_phandle(host_fdt, host_phandle);
+    if (ret <= 0) {
+        error_report("not able to locate clock handle %d in host device tree\n",
+                     host_phandle);
+        goto out;
+    }
+    ret = fdt_get_path(host_fdt, ret, node_path, 256);
+    if (ret < 0) {
+        error_report("not able to retrieve node path for clock handle %d\n",
+                     host_phandle);
+        goto out;
+    }
+
+    r = qemu_fdt_getprop(host_fdt, node_path, "compatible", &prop_len);
+    if (strcmp(r, "fixed-clock")) {
+        error_report("clock handle %d is not a fixed clock\n", host_phandle);
+        ret = -1;
+        goto out;
+    }
+
+    nodename = strrchr(node_path, '/');
+    qemu_fdt_add_subnode(guest_fdt, nodename);
+
+    inherit_properties(clock_inherited_properties,
+                       ARRAY_SIZE(clock_inherited_properties),
+                       host_fdt, guest_fdt,
+                       node_path, nodename);
+
+    qemu_fdt_setprop_cell(guest_fdt, nodename, "phandle", guest_phandle);
+
+out:
+    return ret;
+}
+
 /* Device Specific Code */
 
 /**
-- 
1.8.3.2