dev: add platform bus and devicetree support

Change-Id: Ief8e159b25d4fc4859c7116da6ff22c15bd3fff0
Type: feature
Signed-off-by: Damjan Marion <damarion@cisco.com>

3 files changed, 202 insertions, 1 deletions

diff --git a/src/vnet/CMakeLists.txt b/src/vnet/CMakeLists.txt
index b7a1bbe58c9..1af2d40eff1 100644
--- a/src/vnet/CMakeLists.txt
+++ b/src/vnet/CMakeLists.txt
@@ -78,8 +78,8 @@ list(APPEND VNET_HEADERS
   dev/args.h
   dev/bus/pci.h
   dev/counters.h
-  dev/dev.h
   dev/dev_funcs.h
+  dev/dev.h
   dev/errors.h
   dev/log.h
   dev/mgmt.h
@@ -960,12 +960,14 @@ list(APPEND VNET_API_FILES
 
 if("${CMAKE_SYSTEM_NAME}" STREQUAL "Linux")
 list(APPEND VNET_SOURCES
+  dev/bus/platform.c
   devices/tap/cli.c
   devices/tap/tap.c
   devices/tap/tapv2_api.c
 )
 
 list(APPEND VNET_HEADERS
+  dev/bus/platform.h
   devices/tap/tap.h
 )
 
diff --git a/src/vnet/dev/bus/platform.c b/src/vnet/dev/bus/platform.c
new file mode 100644
index 00000000000..56a1f9c762c
--- /dev/null
+++ b/src/vnet/dev/bus/platform.c
@@ -0,0 +1,172 @@
+/* SPDX-License-Identifier: Apache-2.0
+ * Copyright (c) 2024 Cisco Systems, Inc.
+ */
+
+#include <vnet/vnet.h>
+#include <vnet/dev/dev.h>
+#include <vnet/dev/bus/platform.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <dirent.h>
+
+VLIB_REGISTER_LOG_CLASS (dev_log, static) = {
+  .class_name = "dev",
+  .subclass_name = "platform",
+};
+
+#define log_debug(dev, f, ...)                                                \
+  vlib_log (VLIB_LOG_LEVEL_DEBUG, dev_log.class, "%U" f, format_vnet_dev_log, \
+	    dev,                                                              \
+	    clib_string_skip_prefix (__func__, "vnet_dev_bus_platform_dt_"),  \
+	    ##__VA_ARGS__)
+#define log_err(dev, f, ...)                                                  \
+  vlib_log (VLIB_LOG_LEVEL_ERR, dev_log.class, "%U" f, format_vnet_dev_log,   \
+	    dev, 0, ##__VA_ARGS__)
+
+#define PLATFORM_DEV_PATH "/sys/bus/platform/devices"
+
+clib_dt_main_t vnet_dev_bus_platform_dt_main;
+
+vnet_dev_rv_t
+vnet_dev_bus_platform_dt_node_from_device_id (clib_dt_node_t **nodep,
+					      char *device_id)
+{
+  clib_dt_main_t *dm = &vnet_dev_bus_platform_dt_main;
+  clib_dt_node_t *n;
+  char *name = device_id + sizeof (PLATFORM_BUS_NAME);
+  char path[PATH_MAX];
+  int r;
+  u8 *link;
+
+  if (dm->root == 0)
+    {
+      clib_error_t *err;
+      err = clib_dt_read_from_sysfs (&vnet_dev_bus_platform_dt_main);
+      if (err)
+	{
+	  log_err (0, "cannot read devicetree: %U", format_clib_error, err);
+	  clib_error_free (err);
+	  return VNET_DEV_ERR_NOT_FOUND;
+	}
+    }
+
+  link = format (0, PLATFORM_DEV_PATH "/%s/of_node%c", name, 0);
+  r = readlink ((char *) link, path, sizeof (path) - 1);
+
+  if (r < 1)
+    {
+      log_err (0, "of_node doesn't exist for '%s'", name);
+      vec_free (link);
+      return VNET_DEV_ERR_NOT_FOUND;
+    }
+
+  path[r] = 0;
+  vec_reset_length (link);
+  link = format (link, PLATFORM_DEV_PATH "/%s/%s%c", name, path, 0);
+  if (!realpath ((char *) link, path))
+    {
+      log_err (0, "cannot find realpath for '%s'", link);
+      vec_free (link);
+      return VNET_DEV_ERR_NOT_FOUND;
+    }
+
+  vec_free (link);
+
+  if (strncmp (CLIB_DT_LINUX_PREFIX, path,
+	       sizeof (CLIB_DT_LINUX_PREFIX) - 1) != 0)
+    return VNET_DEV_ERR_BUG;
+
+  n = clib_dt_get_node_with_path (dm, "%s",
+				  path + sizeof (CLIB_DT_LINUX_PREFIX) - 1);
+
+  if (n)
+    {
+      *nodep = n;
+      return VNET_DEV_OK;
+    }
+
+  return VNET_DEV_ERR_NOT_FOUND;
+}
+
+static void *
+vnet_dev_bus_platform_get_device_info (vlib_main_t *vm, char *device_id)
+{
+  clib_dt_node_t *n = 0;
+  vnet_dev_bus_platform_device_info_t *di;
+
+  vnet_dev_bus_platform_dt_node_from_device_id (&n, device_id);
+
+  if (n)
+    {
+      clib_dt_property_t *compatible;
+      compatible = clib_dt_get_node_property_by_name (n, "compatible");
+      log_debug (0, "node found, is compatible %U",
+		 format_clib_dt_property_data, compatible);
+      di = clib_mem_alloc (sizeof (*di));
+      di->node = n;
+      return di;
+    }
+
+  return 0;
+}
+
+static void
+vnet_dev_bus_platform_free_device_info (vlib_main_t *vm, void *p)
+{
+  clib_mem_free (p);
+}
+
+static void
+vnet_dev_bus_platform_close (vlib_main_t *vm, vnet_dev_t *dev)
+{
+  log_debug (dev, "");
+}
+
+static vnet_dev_rv_t
+vnet_dev_bus_platform_open (vlib_main_t *vm, vnet_dev_t *dev)
+{
+  clib_dt_node_t *n = 0;
+  vnet_dev_bus_platform_device_data_t *dd = vnet_dev_get_bus_data (dev);
+  vnet_dev_rv_t rv;
+
+  log_debug (dev, "");
+
+  rv = vnet_dev_bus_platform_dt_node_from_device_id (&n, dev->device_id);
+  if (rv != VNET_DEV_OK)
+    return rv;
+
+  dd->node = n;
+  return VNET_DEV_OK;
+}
+
+static u8 *
+format_dev_bus_platform_device_info (u8 *s, va_list *args)
+{
+  vnet_dev_format_args_t __clib_unused *a =
+    va_arg (*args, vnet_dev_format_args_t *);
+  vnet_dev_t *dev = va_arg (*args, vnet_dev_t *);
+  vnet_dev_bus_platform_device_data_t *dd = vnet_dev_get_bus_data (dev);
+  return format (s, "device-tree path is '%v'", dd->node->path);
+}
+
+static u8 *
+format_dev_bus_platform_device_addr (u8 *s, va_list *args)
+{
+  vnet_dev_t *dev = va_arg (*args, vnet_dev_t *);
+  return format (s, "%s", dev->device_id + sizeof (PLATFORM_BUS_NAME));
+}
+
+VNET_DEV_REGISTER_BUS (pp2) = {
+  .name = PLATFORM_BUS_NAME,
+  .device_data_size = sizeof (vnet_dev_bus_platform_device_info_t),
+  .ops = {
+    .get_device_info = vnet_dev_bus_platform_get_device_info,
+    .free_device_info = vnet_dev_bus_platform_free_device_info,
+    .device_open = vnet_dev_bus_platform_open,
+    .device_close = vnet_dev_bus_platform_close,
+    .format_device_info = format_dev_bus_platform_device_info,
+    .format_device_addr = format_dev_bus_platform_device_addr,
+  },
+};
diff --git a/src/vnet/dev/bus/platform.h b/src/vnet/dev/bus/platform.h
new file mode 100644
index 00000000000..3492aad57ed
--- /dev/null
+++ b/src/vnet/dev/bus/platform.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: Apache-2.0
+ * Copyright (c) 2023 Cisco Systems, Inc.
+ */
+
+#ifndef _VNET_DEV_BUS_PLATFORM_H_
+#define _VNET_DEV_BUS_PLATFORM_H_
+
+#include <vppinfra/clib.h>
+#include <vppinfra/devicetree.h>
+#include <vlib/vlib.h>
+#include <vnet/dev/dev.h>
+
+#define PLATFORM_BUS_NAME "platform"
+
+extern clib_dt_main_t vnet_dev_bus_platform_dt_main;
+
+typedef struct
+{
+  clib_dt_node_t *node;
+} vnet_dev_bus_platform_device_info_t;
+
+typedef struct
+{
+  clib_dt_node_t *node;
+} vnet_dev_bus_platform_device_data_t;
+
+#endif /* _VNET_DEV_BUS_PLATFORM_H_ */