[U-Boot] [PATCH v3 02/19] dm: timer: uclass: add timer init to add timer device

[Mugunthan V N]

Adding timer_init function to create and initialize the timer
device on platforms where u-boot,dm-pre-reloc is not used. Since
there will be multiple timer devices in the system, adding a
tick-timer node in chosen node to know which timer device to be
used as tick timer in u-boot.

Signed-off-by: Mugunthan V N <mugunthanvnm at ti.com>
---

Submitting 02/19 only for v3 as there is no change on other
patches and to reduce traffic.

This patch is verified on AM437x SK and DRA74 EVM logs [1] and
pushed a branch for testing

[1] - http://pastebin.ubuntu.com/14205433/
[2] - git://git.ti.com/~mugunthanvnm/ti-u-boot/mugunth-ti-u-boot.git dm-timer-v3

Changes from v2->v3:
* Fixed issue which is in v2 that if no chosen timer node is
  present in DT then timer init always fails without trying
  first available timer.

---
 doc/device-tree-bindings/chosen.txt | 43 +++++++++++++++++++++++++++++++++++++
 drivers/timer/timer-uclass.c        | 41 +++++++++++++++++++++++++++++++++++
 lib/time.c                          | 13 ++---------
 3 files changed, 86 insertions(+), 11 deletions(-)
 create mode 100644 doc/device-tree-bindings/chosen.txt

diff --git a/doc/device-tree-bindings/chosen.txt b/doc/device-tree-bindings/chosen.txt
new file mode 100644
index 0000000..bf9a30a
--- /dev/null
+++ b/doc/device-tree-bindings/chosen.txt
@@ -0,0 +1,43 @@
+The chosen node
+---------------
+The chosen node does not represent a real device, but serves as a place
+for passing data like which serial device to used to print the logs etc
+
+
+stdout-path property
+--------------------
+Device trees may specify the device to be used for boot console output
+with a stdout-path property under /chosen.
+
+Example
+-------
+/ {
+	chosen {
+		stdout-path = "/serial at f00:115200";
+	};
+
+	serial at f00 {
+		compatible = "vendor,some-uart";
+		reg = <0xf00 0x10>;
+	};
+};
+
+tick-timer property
+-------------------
+In a system there are multiple timers, specify which timer to be used
+as the tick-timer. Earlier it was hardcoded in the timer driver now
+since device tree has all the timer nodes. Specify which timer to be
+used as tick timer.
+
+Example
+-------
+/ {
+	chosen {
+		tick-timer = "/timer2 at f00";
+	};
+
+	timer2 at f00 {
+		compatible = "vendor,some-timer";
+		reg = <0xf00 0x10>;
+	};
+};
diff --git a/drivers/timer/timer-uclass.c b/drivers/timer/timer-uclass.c
index aca421b..b6699f2 100644
--- a/drivers/timer/timer-uclass.c
+++ b/drivers/timer/timer-uclass.c
@@ -6,6 +6,8 @@
 
 #include <common.h>
 #include <dm.h>
+#include <dm/lists.h>
+#include <dm/device-internal.h>
 #include <errno.h>
 #include <timer.h>
 
@@ -56,6 +58,45 @@ u64 timer_conv_64(u32 count)
 	return ((u64)gd->timebase_h << 32) | gd->timebase_l;
 }
 
+int timer_init(void)
+{
+	const void *blob = gd->fdt_blob;
+	struct udevice *dev = NULL;
+	int node;
+	int ret;
+
+	/* Check for a chosen timer to be used for tick */
+	node = fdtdec_get_chosen_node(blob, "tick-timer");
+	if (node < 0) {
+		/* No chosen timer, trying first available timer */
+		ret = uclass_first_device(UCLASS_TIMER, &dev);
+		if (ret)
+			return ret;
+		if (!dev)
+			return -ENODEV;
+	} else {
+		if (uclass_get_device_by_of_offset(UCLASS_TIMER, node, &dev)) {
+			/*
+			 * If the timer is not marked to be bound before
+			 * relocation, bind it anyway.
+			 */
+			if (node > 0 &&
+			    !lists_bind_fdt(gd->dm_root, blob, node, &dev)) {
+				int ret = device_probe(dev);
+				if (ret)
+					return ret;
+			}
+		}
+	}
+
+	if (dev) {
+		gd->timer = dev;
+		return 0;
+	}
+
+	return -ENODEV;
+}
+
 UCLASS_DRIVER(timer) = {
 	.id		= UCLASS_TIMER,
 	.name		= "timer",
diff --git a/lib/time.c b/lib/time.c
index f37a662..d4060f1 100644
--- a/lib/time.c
+++ b/lib/time.c
@@ -43,17 +43,8 @@ extern unsigned long __weak timer_read_counter(void);
 #ifdef CONFIG_TIMER
 static int notrace dm_timer_init(void)
 {
-	struct udevice *dev;
-	int ret;
-
-	if (!gd->timer) {
-		ret = uclass_first_device(UCLASS_TIMER, &dev);
-		if (ret)
-			return ret;
-		if (!dev)
-			return -ENODEV;
-		gd->timer = dev;
-	}
+	if (!gd->timer)
+		return timer_init();
 
 	return 0;
 }
-- 
2.7.0.rc1.5.gf3adf45