clocksource: Add Allwinner SoCs HS timers driver

Most of the Allwinner SoCs (at this time, all but the A10) also have a
High Speed timers that are not using the 24MHz oscillator as a source
but rather the AHB clock running much faster.

The IP is slightly different between the A10s/A13 and the one used in
the A20/A31, since the latter have 4 timers available, while the former
have only 2 of them.

[dlezcano] : Fixed conflict with b788beda "Order Kconfig options
		alphabetically"
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Tested-by: Emilio López <emilio@elopez.com.ar>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

Documentation/devicetree/bindings/timer/allwinner,sun5i-a13-hstimer.txt

+Allwinner SoCs High Speed Timer Controller
+
+Required properties:
+
+- compatible :	should be "allwinner,sun5i-a13-hstimer" or
+		"allwinner,sun7i-a20-hstimer"
+- reg : Specifies base physical address and size of the registers.
+- interrupts :	The interrupts of these timers (2 for the sun5i IP, 4 for the sun7i
+		one)
+- clocks: phandle to the source clock (usually the AHB clock)
+
+Example:
+
+timer@01c60000 {
+	compatible = "allwinner,sun7i-a20-hstimer";
+	reg = <0x01c60000 0x1000>;
+	interrupts = <0 51 1>,
+		     <0 52 1>,
+		     <0 53 1>,
+		     <0 54 1>;
+	clocks = <&ahb1_gates 19>;
+};

arch/arm/mach-sunxi/Kconfig

@@ -12,3 +12,4 @@ config ARCH_SUNXI
 	select PINCTRL_SUNXI
 	select SPARSE_IRQ
 	select SUN4I_TIMER
+	select SUN5I_HSTIMER

drivers/clocksource/Kconfig

@@ -37,6 +37,10 @@ config SUN4I_TIMER
 	select CLKSRC_MMIO
 	bool
 
+config SUN5I_HSTIMER
+	select CLKSRC_MMIO
+	bool
+
 config VT8500_TIMER
 	bool
 

drivers/clocksource/Makefile

@@ -22,6 +22,7 @@ obj-$(CONFIG_ARCH_MOXART)	+= moxart_timer.o
 obj-$(CONFIG_ARCH_MXS)		+= mxs_timer.o
 obj-$(CONFIG_ARCH_PRIMA2)	+= timer-prima2.o
 obj-$(CONFIG_SUN4I_TIMER)	+= sun4i_timer.o
+obj-$(CONFIG_SUN5I_HSTIMER)	+= timer-sun5i.o
 obj-$(CONFIG_ARCH_TEGRA)	+= tegra20_timer.o
 obj-$(CONFIG_VT8500_TIMER)	+= vt8500_timer.o
 obj-$(CONFIG_ARCH_NSPIRE)	+= zevio-timer.o

drivers/clocksource/timer-sun5i.c

+/*
+ * Allwinner SoCs hstimer driver.
+ *
+ * Copyright (C) 2013 Maxime Ripard
+ *
+ * Maxime Ripard <maxime.ripard@free-electrons.com>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2.  This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irqreturn.h>
+#include <linux/sched_clock.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+
+#define TIMER_IRQ_EN_REG		0x00
+#define TIMER_IRQ_EN(val)			BIT(val)
+#define TIMER_IRQ_ST_REG		0x04
+#define TIMER_CTL_REG(val)		(0x20 * (val) + 0x10)
+#define TIMER_CTL_ENABLE			BIT(0)
+#define TIMER_CTL_RELOAD			BIT(1)
+#define TIMER_CTL_CLK_PRES(val)			(((val) & 0x7) << 4)
+#define TIMER_CTL_ONESHOT			BIT(7)
+#define TIMER_INTVAL_LO_REG(val)	(0x20 * (val) + 0x14)
+#define TIMER_INTVAL_HI_REG(val)	(0x20 * (val) + 0x18)
+#define TIMER_CNTVAL_LO_REG(val)	(0x20 * (val) + 0x1c)
+#define TIMER_CNTVAL_HI_REG(val)	(0x20 * (val) + 0x20)
+
+#define TIMER_SYNC_TICKS	3
+
+static void __iomem *timer_base;
+static u32 ticks_per_jiffy;
+
+/*
+ * When we disable a timer, we need to wait at least for 2 cycles of
+ * the timer source clock. We will use for that the clocksource timer
+ * that is already setup and runs at the same frequency than the other
+ * timers, and we never will be disabled.
+ */
+static void sun5i_clkevt_sync(void)
+{
+	u32 old = readl(timer_base + TIMER_CNTVAL_LO_REG(1));
+
+	while ((old - readl(timer_base + TIMER_CNTVAL_LO_REG(1))) < TIMER_SYNC_TICKS)
+		cpu_relax();
+}
+
+static void sun5i_clkevt_time_stop(u8 timer)
+{
+	u32 val = readl(timer_base + TIMER_CTL_REG(timer));
+	writel(val & ~TIMER_CTL_ENABLE, timer_base + TIMER_CTL_REG(timer));
+
+	sun5i_clkevt_sync();
+}
+
+static void sun5i_clkevt_time_setup(u8 timer, u32 delay)
+{
+	writel(delay, timer_base + TIMER_INTVAL_LO_REG(timer));
+}
+
+static void sun5i_clkevt_time_start(u8 timer, bool periodic)
+{
+	u32 val = readl(timer_base + TIMER_CTL_REG(timer));
+
+	if (periodic)
+		val &= ~TIMER_CTL_ONESHOT;
+	else
+		val |= TIMER_CTL_ONESHOT;
+
+	writel(val | TIMER_CTL_ENABLE | TIMER_CTL_RELOAD,
+	       timer_base + TIMER_CTL_REG(timer));
+}
+
+static void sun5i_clkevt_mode(enum clock_event_mode mode,
+			      struct clock_event_device *clk)
+{
+	switch (mode) {
+	case CLOCK_EVT_MODE_PERIODIC:
+		sun5i_clkevt_time_stop(0);
+		sun5i_clkevt_time_setup(0, ticks_per_jiffy);
+		sun5i_clkevt_time_start(0, true);
+		break;
+	case CLOCK_EVT_MODE_ONESHOT:
+		sun5i_clkevt_time_stop(0);
+		sun5i_clkevt_time_start(0, false);
+		break;
+	case CLOCK_EVT_MODE_UNUSED:
+	case CLOCK_EVT_MODE_SHUTDOWN:
+	default:
+		sun5i_clkevt_time_stop(0);
+		break;
+	}
+}
+
+static int sun5i_clkevt_next_event(unsigned long evt,
+				   struct clock_event_device *unused)
+{
+	sun5i_clkevt_time_stop(0);
+	sun5i_clkevt_time_setup(0, evt - TIMER_SYNC_TICKS);
+	sun5i_clkevt_time_start(0, false);
+
+	return 0;
+}
+
+static struct clock_event_device sun5i_clockevent = {
+	.name = "sun5i_tick",
+	.rating = 340,
+	.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+	.set_mode = sun5i_clkevt_mode,
+	.set_next_event = sun5i_clkevt_next_event,
+};
+
+
+static irqreturn_t sun5i_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = (struct clock_event_device *)dev_id;
+
+	writel(0x1, timer_base + TIMER_IRQ_ST_REG);
+	evt->event_handler(evt);
+
+	return IRQ_HANDLED;
+}
+
+static struct irqaction sun5i_timer_irq = {
+	.name = "sun5i_timer0",
+	.flags = IRQF_TIMER | IRQF_IRQPOLL,
+	.handler = sun5i_timer_interrupt,
+	.dev_id = &sun5i_clockevent,
+};
+
+static u32 sun5i_timer_sched_read(void)
+{
+	return ~readl(timer_base + TIMER_CNTVAL_LO_REG(1));
+}
+
+static void __init sun5i_timer_init(struct device_node *node)
+{
+	unsigned long rate;
+	struct clk *clk;
+	int ret, irq;
+	u32 val;
+
+	timer_base = of_iomap(node, 0);
+	if (!timer_base)
+		panic("Can't map registers");
+
+	irq = irq_of_parse_and_map(node, 0);
+	if (irq <= 0)
+		panic("Can't parse IRQ");
+
+	clk = of_clk_get(node, 0);
+	if (IS_ERR(clk))
+		panic("Can't get timer clock");
+	clk_prepare_enable(clk);
+	rate = clk_get_rate(clk);
+
+	writel(~0, timer_base + TIMER_INTVAL_LO_REG(1));
+	writel(TIMER_CTL_ENABLE | TIMER_CTL_RELOAD,
+	       timer_base + TIMER_CTL_REG(1));
+
+	setup_sched_clock(sun5i_timer_sched_read, 32, rate);
+	clocksource_mmio_init(timer_base + TIMER_CNTVAL_LO_REG(1), node->name,
+			      rate, 340, 32, clocksource_mmio_readl_down);
+
+	ticks_per_jiffy = DIV_ROUND_UP(rate, HZ);
+
+	ret = setup_irq(irq, &sun5i_timer_irq);
+	if (ret)
+		pr_warn("failed to setup irq %d\n", irq);
+
+	/* Enable timer0 interrupt */
+	val = readl(timer_base + TIMER_IRQ_EN_REG);
+	writel(val | TIMER_IRQ_EN(0), timer_base + TIMER_IRQ_EN_REG);
+
+	sun5i_clockevent.cpumask = cpu_possible_mask;
+	sun5i_clockevent.irq = irq;
+
+	clockevents_config_and_register(&sun5i_clockevent, rate,
+					TIMER_SYNC_TICKS, 0xffffffff);
+}
+CLOCKSOURCE_OF_DECLARE(sun5i_a13, "allwinner,sun5i-a13-hstimer",
+		       sun5i_timer_init);
+CLOCKSOURCE_OF_DECLARE(sun7i_a20, "allwinner,sun7i-a20-hstimer",
+		       sun5i_timer_init);