aspeed: Add drivers common to all Aspeed SoCs

Add support for Watchdog Timer, which is compatible with AST2400 and
AST2500 watchdogs. There is no uclass for Watchdog yet, so the driver
does not follow the driver model. It also uses fixed clock, so no clock
driver is needed.

Add support for timer for Aspeed ast2400/ast2500 devices.
The driver actually controls several devices, but because all devices
share the same Control Register, it is somewhat difficult to completely
decouple them. Since only one timer is needed at the moment, this should
be OK. The timer uses fixed clock, so does not rely on a clock driver.

Add sysreset driver, which uses watchdog timer to do resets and particular
watchdog device to use is hardcoded (0)
Reviewed-by: Simon Glass <sjg@chromium.org>

3 files changed, 110 insertions, 0 deletions

diff --git a/drivers/timer/Kconfig b/drivers/timer/Kconfig
index cb18f12fc99..cd38a6d4bd9 100644
--- a/drivers/timer/Kconfig
+++ b/drivers/timer/Kconfig
@@ -46,4 +46,16 @@ config OMAP_TIMER
 	help
 	  Select this to enable an timer for Omap devices.
 
+config AST_TIMER
+	bool "Aspeed ast2400/ast2500 timer support"
+	depends on TIMER
+	default y if ARCH_ASPEED
+	help
+	  Select this to enable timer for Aspeed ast2400/ast2500 devices.
+	  This is a simple sys timer driver, it is compatible with lib/time.c,
+	  but does not support any interrupts. Even though SoC has 8 hardware
+	  counters, they are all treated as a single device by this driver.
+	  This is mostly because they all share several registers which
+	  makes it difficult to completely separate them.
+
 endmenu
diff --git a/drivers/timer/Makefile b/drivers/timer/Makefile
index f351fbb4e0c..a4b1a486b0f 100644
--- a/drivers/timer/Makefile
+++ b/drivers/timer/Makefile
@@ -9,3 +9,4 @@ obj-$(CONFIG_ALTERA_TIMER)	+= altera_timer.o
 obj-$(CONFIG_SANDBOX_TIMER)	+= sandbox_timer.o
 obj-$(CONFIG_X86_TSC_TIMER)	+= tsc_timer.o
 obj-$(CONFIG_OMAP_TIMER)	+= omap-timer.o
+obj-$(CONFIG_AST_TIMER)	+= ast_timer.o
diff --git a/drivers/timer/ast_timer.c b/drivers/timer/ast_timer.c
new file mode 100644
index 00000000000..d7c5460cd3c
--- /dev/null
+++ b/drivers/timer/ast_timer.c
@@ -0,0 +1,97 @@
+/*
+ * Copyright 2016 Google Inc.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <timer.h>
+#include <asm/io.h>
+#include <asm/arch/timer.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+#define AST_TICK_TIMER  1
+#define AST_TMC_RELOAD_VAL  0xffffffff
+
+struct ast_timer_priv {
+	struct ast_timer *regs;
+	struct ast_timer_counter *tmc;
+};
+
+static struct ast_timer_counter *ast_get_timer_counter(struct ast_timer *timer,
+						       int n)
+{
+	if (n > 3)
+		return &timer->timers2[n - 4];
+	else
+		return &timer->timers1[n - 1];
+}
+
+static int ast_timer_probe(struct udevice *dev)
+{
+	struct ast_timer_priv *priv = dev_get_priv(dev);
+	struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+
+	writel(AST_TMC_RELOAD_VAL, &priv->tmc->reload_val);
+
+	/*
+	 * Stop the timer. This will also load reload_val into
+	 * the status register.
+	 */
+	clrbits_le32(&priv->regs->ctrl1,
+		     AST_TMC_EN << AST_TMC_CTRL1_SHIFT(AST_TICK_TIMER));
+	/* Start the timer from the fixed 1MHz clock. */
+	setbits_le32(&priv->regs->ctrl1,
+		     (AST_TMC_EN | AST_TMC_1MHZ) <<
+		     AST_TMC_CTRL1_SHIFT(AST_TICK_TIMER));
+
+	uc_priv->clock_rate = AST_TMC_RATE;
+
+	return 0;
+}
+
+static int ast_timer_get_count(struct udevice *dev, u64 *count)
+{
+	struct ast_timer_priv *priv = dev_get_priv(dev);
+
+	*count = AST_TMC_RELOAD_VAL - readl(&priv->tmc->status);
+
+	return 0;
+}
+
+static int ast_timer_ofdata_to_platdata(struct udevice *dev)
+{
+	struct ast_timer_priv *priv = dev_get_priv(dev);
+
+	priv->regs = dev_get_addr_ptr(dev);
+	if (IS_ERR(priv->regs))
+		return PTR_ERR(priv->regs);
+
+	priv->tmc = ast_get_timer_counter(priv->regs, AST_TICK_TIMER);
+
+	return 0;
+}
+
+static const struct timer_ops ast_timer_ops = {
+	.get_count = ast_timer_get_count,
+};
+
+static const struct udevice_id ast_timer_ids[] = {
+	{ .compatible = "aspeed,ast2500-timer" },
+	{ .compatible = "aspeed,ast2400-timer" },
+	{ }
+};
+
+U_BOOT_DRIVER(ast_timer) = {
+	.name = "ast_timer",
+	.id = UCLASS_TIMER,
+	.of_match = ast_timer_ids,
+	.probe = ast_timer_probe,
+	.priv_auto_alloc_size = sizeof(struct ast_timer_priv),
+	.ofdata_to_platdata = ast_timer_ofdata_to_platdata,
+	.ops = &ast_timer_ops,
+	.flags = DM_FLAG_PRE_RELOC,
+};