clocksource: clps711x: Add CLPS711X clocksource driver

This adds the clocksource driver for Cirrus Logic CLPS711X series SoCs.
Designed primarily for migration CLPS711X subarch for multiplatform & DT,
for this as the "OF" and "non-OF" calls implemented.

Signed-off-by: Alexander Shiyan <[e-mail]>
Acked-by: Arnd Bergmann <[e-mail]>
Signed-off-by: Daniel Lezcano <[e-mail]>

drivers/clocksource/Makefile

···
 obj-$(CONFIG_ARMADA_370_XP_TIMER)	+= time-armada-370-xp.o
 obj-$(CONFIG_ORION_TIMER)	+= time-orion.o
 obj-$(CONFIG_ARCH_BCM2835)	+= bcm2835_timer.o
+obj-$(CONFIG_ARCH_CLPS711X)	+= clps711x-timer.o
 obj-$(CONFIG_ARCH_MARCO)	+= timer-marco.o
 obj-$(CONFIG_ARCH_MOXART)	+= moxart_timer.o
 obj-$(CONFIG_ARCH_MXS)		+= mxs_timer.o

drivers/clocksource/clps711x-timer.c

···
+/*
+ *  Cirrus Logic CLPS711X clocksource driver
+ *
+ *  Copyright (C) 2014 Alexander Shiyan <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/sched_clock.h>
+#include <linux/slab.h>
+
+enum {
+	CLPS711X_CLKSRC_CLOCKSOURCE,
+	CLPS711X_CLKSRC_CLOCKEVENT,
+};
+
+static void __iomem *tcd;
+
+static u64 notrace clps711x_sched_clock_read(void)
+{
+	return ~readw(tcd);
+}
+
+static int __init _clps711x_clksrc_init(struct clk *clock, void __iomem *base)
+{
+	unsigned long rate;
+
+	if (!base)
+		return -ENOMEM;
+	if (IS_ERR(clock))
+		return PTR_ERR(clock);
+
+	rate = clk_get_rate(clock);
+
+	tcd = base;
+
+	clocksource_mmio_init(tcd, "clps711x-clocksource", rate, 300, 16,
+			      clocksource_mmio_readw_down);
+
+	sched_clock_register(clps711x_sched_clock_read, 16, rate);
+
+	return 0;
+}
+
+static irqreturn_t clps711x_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = dev_id;
+
+	evt->event_handler(evt);
+
+	return IRQ_HANDLED;
+}
+
+static void clps711x_clockevent_set_mode(enum clock_event_mode mode,
+					 struct clock_event_device *evt)
+{
+}
+
+static int __init _clps711x_clkevt_init(struct clk *clock, void __iomem *base,
+					unsigned int irq)
+{
+	struct clock_event_device *clkevt;
+	unsigned long rate;
+
+	if (!irq)
+		return -EINVAL;
+	if (!base)
+		return -ENOMEM;
+	if (IS_ERR(clock))
+		return PTR_ERR(clock);
+
+	clkevt = kzalloc(sizeof(*clkevt), GFP_KERNEL);
+	if (!clkevt)
+		return -ENOMEM;
+
+	rate = clk_get_rate(clock);
+
+	/* Set Timer prescaler */
+	writew(DIV_ROUND_CLOSEST(rate, HZ), base);
+
+	clkevt->name = "clps711x-clockevent";
+	clkevt->rating = 300;
+	clkevt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_C3STOP;
+	clkevt->set_mode = clps711x_clockevent_set_mode;
+	clkevt->cpumask = cpumask_of(0);
+	clockevents_config_and_register(clkevt, HZ, 0, 0);
+
+	return request_irq(irq, clps711x_timer_interrupt, IRQF_TIMER,
+			   "clps711x-timer", clkevt);
+}
+
+void __init clps711x_clksrc_init(void __iomem *tc1_base, void __iomem *tc2_base,
+				 unsigned int irq)
+{
+	struct clk *tc1 = clk_get_sys("clps711x-timer.0", NULL);
+	struct clk *tc2 = clk_get_sys("clps711x-timer.1", NULL);
+
+	BUG_ON(_clps711x_clksrc_init(tc1, tc1_base));
+	BUG_ON(_clps711x_clkevt_init(tc2, tc2_base, irq));
+}
+
+#ifdef CONFIG_CLKSRC_OF
+static void __init clps711x_timer_init(struct device_node *np)
+{
+	unsigned int irq = irq_of_parse_and_map(np, 0);
+	struct clk *clock = of_clk_get(np, 0);
+	void __iomem *base = of_iomap(np, 0);
+
+	switch (of_alias_get_id(np, "timer")) {
+	case CLPS711X_CLKSRC_CLOCKSOURCE:
+		BUG_ON(_clps711x_clksrc_init(clock, base));
+		break;
+	case CLPS711X_CLKSRC_CLOCKEVENT:
+		BUG_ON(_clps711x_clkevt_init(clock, base, irq));
+		break;
+	default:
+		break;
+	}
+}
+CLOCKSOURCE_OF_DECLARE(clps711x, "cirrus,clps711x-timer", clps711x_timer_init);
+#endif