From 50162348f0d3b915004733131acd81805e202c76 Mon Sep 17 00:00:00 2001
From: Simon Glass <sjg@chromium.org>
Date: Thu, 6 Feb 2020 09:54:50 -0700
Subject: [PATCH] dm: core: Add a function to find a device by drvdata

It is sometimes useful to find a device in a uclass using only its driver
data. The driver data often indicates the 'subtype' of the device, e,g,
via its compatible string.

Add a function to handle this.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
---
 drivers/core/uclass.c | 17 +++++++++++++++++
 include/dm/test.h     |  2 ++
 include/dm/uclass.h   | 14 ++++++++++++++
 test/dm/test-fdt.c    | 21 +++++++++++++++++++++
 4 files changed, 54 insertions(+)

diff --git a/drivers/core/uclass.c b/drivers/core/uclass.c
index c520ef113a..61192d8a9f 100644
--- a/drivers/core/uclass.c
+++ b/drivers/core/uclass.c
@@ -629,6 +629,23 @@ int uclass_next_device_check(struct udevice **devp)
 	return device_probe(*devp);
 }
 
+int uclass_first_device_drvdata(enum uclass_id id, ulong driver_data,
+				struct udevice **devp)
+{
+	struct udevice *dev;
+	struct uclass *uc;
+
+	uclass_id_foreach_dev(id, dev, uc) {
+		if (dev_get_driver_data(dev) == driver_data) {
+			*devp = dev;
+
+			return device_probe(dev);
+		}
+	}
+
+	return -ENODEV;
+}
+
 int uclass_bind_device(struct udevice *dev)
 {
 	struct uclass *uc;
diff --git a/include/dm/test.h b/include/dm/test.h
index 07385cd531..f0f36624ce 100644
--- a/include/dm/test.h
+++ b/include/dm/test.h
@@ -56,6 +56,8 @@ enum {
 enum {
 	DM_TEST_TYPE_FIRST = 0,
 	DM_TEST_TYPE_SECOND,
+
+	DM_TEST_TYPE_COUNT,
 };
 
 /* The number added to the ping total on each probe */
diff --git a/include/dm/uclass.h b/include/dm/uclass.h
index 74b8e2ecb5..70fca79b44 100644
--- a/include/dm/uclass.h
+++ b/include/dm/uclass.h
@@ -350,6 +350,20 @@ int uclass_first_device_check(enum uclass_id id, struct udevice **devp);
  */
 int uclass_next_device_check(struct udevice **devp);
 
+/**
+ * uclass_first_device_drvdata() - Find the first device with given driver data
+ *
+ * This searches through the devices for a particular uclass looking for one
+ * that has the given driver data.
+ *
+ * @id: Uclass ID to check
+ * @driver_data: Driver data to search for
+ * @devp: Returns pointer to the first matching device in that uclass, if found
+ * @return 0 if found, -ENODEV if not found, other -ve on error
+ */
+int uclass_first_device_drvdata(enum uclass_id id, ulong driver_data,
+				struct udevice **devp);
+
 /**
  * uclass_resolve_seq() - Resolve a device's sequence number
  *
diff --git a/test/dm/test-fdt.c b/test/dm/test-fdt.c
index 8ea536c309..698ca0e7cf 100644
--- a/test/dm/test-fdt.c
+++ b/test/dm/test-fdt.c
@@ -893,3 +893,24 @@ static int dm_test_read_int(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_read_int, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
+/* Test iteration through devices by drvdata */
+static int dm_test_uclass_drvdata(struct unit_test_state *uts)
+{
+	struct udevice *dev;
+
+	ut_assertok(uclass_first_device_drvdata(UCLASS_TEST_FDT,
+						DM_TEST_TYPE_FIRST, &dev));
+	ut_asserteq_str("a-test", dev->name);
+
+	ut_assertok(uclass_first_device_drvdata(UCLASS_TEST_FDT,
+						DM_TEST_TYPE_SECOND, &dev));
+	ut_asserteq_str("d-test", dev->name);
+
+	ut_asserteq(-ENODEV, uclass_first_device_drvdata(UCLASS_TEST_FDT,
+							 DM_TEST_TYPE_COUNT,
+							 &dev));
+
+	return 0;
+}
+DM_TEST(dm_test_uclass_drvdata, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
-- 
2.25.1