dtoc: Detect drivers which do not parse correctly

At present if a driver is missing a uclass or compatible stirng, this
is silently ignored. This makes sense in most cases, particularly for
the compatible string, since it is not required except when the driver
is used with of-platdata.

But it is also not very helpful. When there is some sort of problem
with a driver, the missing compatible string (for example) may be the
cause.

Add a warning in this case, showing it only for drivers which are used
by the build.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Walter Lozano <walter.lozano@collabora.com>

tools/dtoc/src_scan.py

@@ -546,7 +546,12 @@ class Scanner:
                         # The driver does not have a uclass or compat string.
                         # The first is required but the second is not, so just
                         # ignore this.
-                        pass
+                        if not driver.uclass_id:
+                            warn = 'Missing .uclass'
+                        else:
+                            warn = 'Missing .compatible'
+                        self._warnings[driver.name].add('%s in %s' %
+                                                        (warn, fname))
                     driver = None
                     ids_name = None
                     compat = None

tools/dtoc/test_src_scan.py

@@ -581,3 +581,41 @@ rockchip_rk3288_grf: WARNING: the driver rockchip_rk3288_grf was not found in th
 ''',
             stdout.getvalue())
         self.assertIn('tegra_i2c_ids', stdout.getvalue())
+
+    def scan_uclass_warning(self):
+        """Test a missing .uclass in the driver"""
+        buff = '''
+static const struct udevice_id tegra_i2c_ids[] = {
+	{ .compatible = "nvidia,tegra114-i2c", .data = TYPE_114 },
+	{ }
+};
+
+U_BOOT_DRIVER(i2c_tegra) = {
+	.name	= "i2c_tegra",
+	.of_match = tegra_i2c_ids,
+};
+'''
+        scan = src_scan.Scanner(None, None)
+        scan._parse_driver('file.c', buff)
+        self.assertEqual(
+            {'i2c_tegra': {'Missing .uclass in file.c'}},
+            scan._warnings)
+
+    def scan_compat_warning(self):
+        """Test a missing .compatible in the driver"""
+        buff = '''
+static const struct udevice_id tegra_i2c_ids[] = {
+	{ .compatible = "nvidia,tegra114-i2c", .data = TYPE_114 },
+	{ }
+};
+
+U_BOOT_DRIVER(i2c_tegra) = {
+	.name	= "i2c_tegra",
+	.id	= UCLASS_I2C,
+};
+'''
+        scan = src_scan.Scanner(None, None)
+        scan._parse_driver('file.c', buff)
+        self.assertEqual(
+            {'i2c_tegra': {'Missing .compatible in file.c'}},
+            scan._warnings)