dm: Simple Watchdog uclass

This is a simple uclass for Watchdog Timers. It has four operations:
start, restart, reset, stop. Drivers must implement start, restart and
stop operations, while implementing reset is optional: It's default
implementation expires watchdog timer in one clock tick.

Signed-off-by: Maxim Sloyko <maxims@google.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

4 files changed, 169 insertions, 1 deletions

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index dbdaafc..e8d2dba 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1,8 +1,26 @@
-menu "WATCHDOG support"
+menu "Watchdog Timer Support"
 
 config ULP_WATCHDOG
 	bool "i.MX7ULP watchdog"
 	help
 	  Say Y here to enable i.MX7ULP watchdog driver.
 
+config WDT
+	bool "Enable driver model for watchdog timer drivers"
+	depends on DM
+	help
+	  Enable driver model for watchdog timer. At the moment the API
+	  is very simple and only supports four operations:
+	  start, restart, stop and reset (expire immediately).
+	  What exactly happens when the timer expires is up to a particular
+	  device/driver.
+
+config WDT_SANDBOX
+	bool "Enable Watchdog Timer support for Sandbox"
+	depends on SANDBOX && WDT
+	help
+		Enable Watchdog Timer support in Sandbox. This is a dummy device that
+		can be probed and supports all of the methods of WDT, but does not
+		really do anything.
+
 endmenu
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 36745ca..e891d64 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -15,3 +15,5 @@ obj-$(CONFIG_XILINX_TB_WATCHDOG) += xilinx_tb_wdt.o
 obj-$(CONFIG_OMAP_WATCHDOG) += omap_wdt.o
 obj-$(CONFIG_DESIGNWARE_WATCHDOG) += designware_wdt.o
 obj-$(CONFIG_ULP_WATCHDOG) += ulp_wdog.o
+obj-$(CONFIG_WDT) += wdt-uclass.o
+obj-$(CONFIG_WDT_SANDBOX) += sandbox_wdt.o
diff --git a/drivers/watchdog/sandbox_wdt.c b/drivers/watchdog/sandbox_wdt.c
new file mode 100644
index 0000000..34d90be
--- /dev/null
+++ b/drivers/watchdog/sandbox_wdt.c
@@ -0,0 +1,76 @@
+/*
+ * Copyright 2017 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <asm/state.h>
+#include <wdt.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+static int sandbox_wdt_start(struct udevice *dev, u64 timeout, ulong flags)
+{
+	struct sandbox_state *state = state_get_current();
+
+	state->wdt.counter = timeout;
+	state->wdt.running = true;
+
+	return 0;
+}
+
+static int sandbox_wdt_stop(struct udevice *dev)
+{
+	struct sandbox_state *state = state_get_current();
+
+	state->wdt.running = false;
+
+	return 0;
+}
+
+static int sandbox_wdt_reset(struct udevice *dev)
+{
+	struct sandbox_state *state = state_get_current();
+
+	state->wdt.reset_count++;
+
+	return 0;
+}
+
+static int sandbox_wdt_expire_now(struct udevice *dev, ulong flags)
+{
+	sandbox_wdt_start(dev, 1, flags);
+
+	return 0;
+}
+
+static int sandbox_wdt_probe(struct udevice *dev)
+{
+	struct sandbox_state *state = state_get_current();
+
+	memset(&state->wdt, 0, sizeof(state->wdt));
+
+	return 0;
+}
+
+static const struct wdt_ops sandbox_wdt_ops = {
+	.start = sandbox_wdt_start,
+	.reset = sandbox_wdt_reset,
+	.stop = sandbox_wdt_stop,
+	.expire_now = sandbox_wdt_expire_now,
+};
+
+static const struct udevice_id sandbox_wdt_ids[] = {
+	{ .compatible = "sandbox,wdt" },
+	{}
+};
+
+U_BOOT_DRIVER(wdt_sandbox) = {
+	.name = "wdt_sandbox",
+	.id = UCLASS_WDT,
+	.of_match = sandbox_wdt_ids,
+	.ops = &sandbox_wdt_ops,
+	.probe = sandbox_wdt_probe,
+};
diff --git a/drivers/watchdog/wdt-uclass.c b/drivers/watchdog/wdt-uclass.c
new file mode 100644
index 0000000..ab8a64c
--- /dev/null
+++ b/drivers/watchdog/wdt-uclass.c
@@ -0,0 +1,72 @@
+/*
+ * Copyright 2017 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <wdt.h>
+#include <dm/device-internal.h>
+#include <dm/lists.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+int wdt_start(struct udevice *dev, u64 timeout, ulong flags)
+{
+	const struct wdt_ops *ops = device_get_ops(dev);
+
+	if (!ops->start)
+		return -ENOSYS;
+
+	return ops->start(dev, timeout, flags);
+}
+
+int wdt_stop(struct udevice *dev)
+{
+	const struct wdt_ops *ops = device_get_ops(dev);
+
+	if (!ops->stop)
+		return -ENOSYS;
+
+	return ops->stop(dev);
+}
+
+int wdt_reset(struct udevice *dev)
+{
+	const struct wdt_ops *ops = device_get_ops(dev);
+
+	if (!ops->reset)
+		return -ENOSYS;
+
+	return ops->reset(dev);
+}
+
+int wdt_expire_now(struct udevice *dev, ulong flags)
+{
+	int ret = 0;
+	const struct wdt_ops *ops;
+
+	debug("WDT Resettting: %lu\n", flags);
+	ops = device_get_ops(dev);
+	if (ops->expire_now) {
+		return ops->expire_now(dev, flags);
+	} else {
+		if (!ops->start)
+			return -ENOSYS;
+
+		ret = ops->start(dev, 1, flags);
+		if (ret < 0)
+			return ret;
+
+		hang();
+	}
+
+	return ret;
+}
+
+UCLASS_DRIVER(wdt) = {
+	.id		= UCLASS_WDT,
+	.name		= "wdt",
+};