dm: implement a Timer uclass

Implement a Timer uclass to work with lib/time.c.

Signed-off-by: Thomas Chou <thomas@wytron.com.tw>
Acked-by: Simon Glass <sjg@chromium.org>

drivers/Kconfig

@@ -58,6 +58,8 @@ source "drivers/spi/Kconfig"
 
 source "drivers/thermal/Kconfig"
 
+source "drivers/timer/Kconfig"
+
 source "drivers/tpm/Kconfig"
 
 source "drivers/usb/Kconfig"

drivers/Makefile

@@ -48,6 +48,7 @@ obj-y += pcmcia/
 obj-y += dfu/
 obj-y += rtc/
 obj-y += sound/
+obj-y += timer/
 obj-y += tpm/
 obj-y += twserial/
 obj-y += video/

drivers/timer/Kconfig

@@ -0,0 +1,12 @@
+menu "Timer Support"
+
+config TIMER
+	bool "Enable Driver Model for Timer drivers"
+	depends on DM
+	help
+	  Enable driver model for Timer access. It uses the same API as
+	  lib/time.c. But now implemented by the uclass. The first timer
+	  will be used. The timer is usually a 32 bits free-running up
+	  counter. There may be no real tick, and no timer interrupt.
+
+endmenu

drivers/timer/Makefile

@@ -0,0 +1,7 @@
+#
+# Copyright (C) 2015 Thomas Chou <thomas@wytron.com.tw>
+#
+# SPDX-License-Identifier:	GPL-2.0+
+#
+
+obj-$(CONFIG_TIMER)		+= timer-uclass.o

drivers/timer/timer-uclass.c

@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2015 Thomas Chou <thomas@wytron.com.tw>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <timer.h>
+
+/*
+ * Implement a Timer uclass to work with lib/time.c. The timer is usually
+ * a 32 bits free-running up counter. The get_rate() method is used to get
+ * the input clock frequency of the timer. The get_count() method is used
+ * get the current 32 bits count value. If the hardware is counting down,
+ * the value should be inversed inside the method. There may be no real
+ * tick, and no timer interrupt.
+ */
+
+int timer_get_count(struct udevice *dev, unsigned long *count)
+{
+	const struct timer_ops *ops = device_get_ops(dev);
+
+	if (!ops->get_count)
+		return -ENOSYS;
+
+	return ops->get_count(dev, count);
+}
+
+unsigned long timer_get_rate(struct udevice *dev)
+{
+	struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	return uc_priv->clock_rate;
+}
+
+UCLASS_DRIVER(timer) = {
+	.id		= UCLASS_TIMER,
+	.name		= "timer",
+	.per_device_auto_alloc_size = sizeof(struct timer_dev_priv),
+};

include/asm-generic/global_data.h

@@ -69,6 +69,9 @@ typedef struct global_data {
 	struct udevice	*dm_root_f;	/* Pre-relocation root instance */
 	struct list_head uclass_root;	/* Head of core tree */
 #endif
+#ifdef CONFIG_TIMER
+	struct udevice	*timer;	/* Timer instance for Driver Model */
+#endif
 
 	const void *fdt_blob;	/* Our device tree, NULL if none */
 	void *new_fdt;		/* Relocated FDT */

include/dm/uclass-id.h

@@ -57,6 +57,7 @@ enum uclass_id {
 	UCLASS_SPI_GENERIC,	/* Generic SPI flash target */
 	UCLASS_SYSCON,		/* System configuration device */
 	UCLASS_THERMAL,		/* Thermal sensor */
+	UCLASS_TIMER,		/* Timer device */
 	UCLASS_TPM,		/* Trusted Platform Module TIS interface */
 	UCLASS_USB,		/* USB bus */
 	UCLASS_USB_DEV_GENERIC,	/* USB generic device */

include/timer.h

@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2015 Thomas Chou <thomas@wytron.com.tw>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef _TIMER_H_
+#define _TIMER_H_
+
+/*
+ * Get the current timer count
+ *
+ * @dev: The Timer device
+ * @count: pointer that returns the current timer count
+ * @return: 0 if OK, -ve on error
+ */
+int timer_get_count(struct udevice *dev, unsigned long *count);
+/*
+ * Get the timer input clock frequency
+ *
+ * @dev: The Timer device
+ * @return: the timer input clock frequency
+ */
+unsigned long timer_get_rate(struct udevice *dev);
+
+/*
+ * struct timer_ops - Driver model Timer operations
+ *
+ * The uclass interface is implemented by all Timer devices which use
+ * driver model.
+ */
+struct timer_ops {
+	/*
+	 * Get the current timer count
+	 *
+	 * @dev: The Timer device
+	 * @count: pointer that returns the current timer count
+	 * @return: 0 if OK, -ve on error
+	 */
+	int (*get_count)(struct udevice *dev, unsigned long *count);
+};
+
+/*
+ * struct timer_dev_priv - information about a device used by the uclass
+ *
+ * @clock_rate: the timer input clock frequency
+ */
+struct timer_dev_priv {
+	unsigned long clock_rate;
+};
+
+#endif	/* _TIMER_H_ */

lib/time.c

@@ -6,6 +6,9 @@
  */
 
 #include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <timer.h>
 #include <watchdog.h>
 #include <div64.h>
 #include <asm/io.h>
@@ -37,6 +40,52 @@ unsigned long notrace timer_read_counter(void)
 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;
+
+	ret = dm_timer_init();
+	if (ret)
+		return ret;
+
+	return timer_get_rate(gd->timer);
+}
+
+unsigned long notrace timer_read_counter(void)
+{
+	unsigned long count;
+	int ret;
+
+	ret = dm_timer_init();
+	if (ret)
+		return ret;
+
+	ret = timer_get_count(gd->timer, &count);
+	if (ret)
+		return ret;
+
+	return count;
+}
+#endif /* CONFIG_TIMER */
+
 uint64_t __weak notrace get_ticks(void)
 {
 	unsigned long now = timer_read_counter();