rockchip: timer: add device-model timer driver for RK3368 (and similar)

This adds a device-model driver for the timer block in the RK3368 (and
similar devices that share the same timer block, such as the RK3288) for
the down-counting (i.e. non-secure) timers.

This allows us to configure U-Boot for the RK3368 in such a way that
we can run with the secure timer inaccessible or uninitialised (note
that the ARMv8 generic timer does not count, if the secure timer is
not enabled).

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/timer/Kconfig

@@ -103,4 +103,11 @@ config AE3XX_TIMER
 	help
 	  Select this to enable a timer for AE3XX devices.
 
+config ROCKCHIP_TIMER
+        bool "Rockchip timer support"
+	depends on TIMER
+	help
+	  Select this to enable support for the timer found on
+	  Rockchip devices.
+
 endmenu

drivers/timer/Makefile

@@ -14,3 +14,4 @@ obj-$(CONFIG_STI_TIMER)		+= sti-timer.o
 obj-$(CONFIG_ARC_TIMER)	+= arc_timer.o
 obj-$(CONFIG_AG101P_TIMER) += ag101p_timer.o
 obj-$(CONFIG_AE3XX_TIMER) += ae3xx_timer.o
+obj-$(CONFIG_ROCKCHIP_TIMER) += rockchip_timer.o

drivers/timer/rockchip_timer.c

@@ -0,0 +1,107 @@
+/*
+ * Copyright (C) 2017 Theobroma Systems Design und Consulting GmbH
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <mapmem.h>
+#include <asm/arch/timer.h>
+#include <dt-structs.h>
+#include <timer.h>
+#include <asm/io.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+#if CONFIG_IS_ENABLED(OF_PLATDATA)
+struct rockchip_timer_plat {
+	struct dtd_rockchip_rk3368_timer dtd;
+};
+#endif
+
+/* Driver private data. Contains timer id. Could be either 0 or 1. */
+struct rockchip_timer_priv {
+	struct rk_timer *timer;
+};
+
+static int rockchip_timer_get_count(struct udevice *dev, u64 *count)
+{
+	struct rockchip_timer_priv *priv = dev_get_priv(dev);
+	uint64_t timebase_h, timebase_l;
+	uint64_t cntr;
+
+	timebase_l = readl(&priv->timer->timer_curr_value0);
+	timebase_h = readl(&priv->timer->timer_curr_value1);
+
+	/* timers are down-counting */
+	cntr = timebase_h << 32 | timebase_l;
+	*count = ~0ull - cntr;
+	return 0;
+}
+
+static int rockchip_clk_ofdata_to_platdata(struct udevice *dev)
+{
+#if !CONFIG_IS_ENABLED(OF_PLATDATA)
+	struct rockchip_timer_priv *priv = dev_get_priv(dev);
+
+	priv->timer = (struct rk_timer *)devfdt_get_addr(dev);
+#endif
+
+	return 0;
+}
+
+static int rockchip_timer_start(struct udevice *dev)
+{
+	struct rockchip_timer_priv *priv = dev_get_priv(dev);
+	const uint64_t reload_val = ~0uLL;
+	const uint32_t reload_val_l = reload_val & 0xffffffff;
+	const uint32_t reload_val_h = reload_val >> 32;
+
+	/* disable timer and reset all control */
+	writel(0, &priv->timer->timer_ctrl_reg);
+	/* write reload value */
+	writel(reload_val_l, &priv->timer->timer_load_count0);
+	writel(reload_val_h, &priv->timer->timer_load_count1);
+	/* enable timer */
+	writel(1, &priv->timer->timer_ctrl_reg);
+
+	return 0;
+}
+
+static int rockchip_timer_probe(struct udevice *dev)
+{
+#if CONFIG_IS_ENABLED(OF_PLATDATA)
+	struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
+	struct rockchip_timer_priv *priv = dev_get_priv(dev);
+	struct rockchip_timer_plat *plat = dev_get_platdata(dev);
+
+	priv->timer = map_sysmem(plat->dtd.reg[1], plat->dtd.reg[3]);
+	uc_priv->clock_rate = plat->dtd.clock_frequency;
+#endif
+
+	return rockchip_timer_start(dev);
+}
+
+static const struct timer_ops rockchip_timer_ops = {
+	.get_count = rockchip_timer_get_count,
+};
+
+static const struct udevice_id rockchip_timer_ids[] = {
+	{ .compatible = "rockchip,rk3368-timer" },
+	{}
+};
+
+U_BOOT_DRIVER(arc_timer) = {
+	.name	= "rockchip_rk3368_timer",
+	.id	= UCLASS_TIMER,
+	.of_match = rockchip_timer_ids,
+	.probe = rockchip_timer_probe,
+	.ops	= &rockchip_timer_ops,
+	.flags = DM_FLAG_PRE_RELOC,
+	.priv_auto_alloc_size = sizeof(struct rockchip_timer_priv),
+#if CONFIG_IS_ENABLED(OF_PLATDATA)
+	.platdata_auto_alloc_size = sizeof(struct rockchip_timer_plat),
+#endif
+	.ofdata_to_platdata = rockchip_clk_ofdata_to_platdata,
+};