dm: timer: uclass: add timer init in uclass driver to add timer device

Adding timer init function in timer-uclass driver 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@ti.com>

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@f00:115200";
+	};
+
+	serial@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@f00";
+	};
+
+	timer2@f00 {
+		compatible = "vendor,some-timer";
+		reg = <0xf00 0x10>;
+	};
+};

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 +58,48 @@ u64 timer_conv_64(u32 count)
 	return ((u64)gd->timebase_h << 32) | gd->timebase_l;
 }
 
+int notrace dm_timer_init(void)
+{
+	const void *blob = gd->fdt_blob;
+	struct udevice *dev = NULL;
+	int node;
+	int ret;
+
+	if (gd->timer)
+		return 0;
+
+	/* 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)) {
+				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",

include/timer.h

@@ -7,6 +7,15 @@
 #ifndef _TIMER_H_
 #define _TIMER_H_
 
+/*
+ * dm_timer_init - initialize a timer for time keeping. On success
+ * initializes gd->timer so that lib/timer can use it for future
+ * referrence.
+ *
+ * @return - 0 on success or error number
+ */
+int dm_timer_init(void);
+
 /*
  * timer_conv_64 - convert 32-bit counter value to 64-bit
  *

lib/time.c

@@ -41,23 +41,6 @@ extern unsigned long __weak timer_read_counter(void);
 #endif
 
 #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;
-	}
-
-	return 0;
-}
-
 ulong notrace get_tbclk(void)
 {
 	int ret;