1 files changed, 373 insertions, 0 deletions
diff --git a/drivers/clocksource/arc_timer.c b/drivers/clocksource/arc_timer.c
new file mode 100644
index 000000000..de93dd1a8
--- /dev/null
+++ b/drivers/clocksource/arc_timer.c
@@ -0,0 +1,373 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2016-17 Synopsys, Inc. (www.synopsys.com)
+ * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
+ */
+
+/* ARC700 has two 32bit independent prog Timers: TIMER0 and TIMER1, Each can be
+ * programmed to go from @count to @limit and optionally interrupt.
+ * We've designated TIMER0 for clockevents and TIMER1 for clocksource
+ *
+ * ARCv2 based HS38 cores have RTC (in-core) and GFRC (inside ARConnect/MCIP)
+ * which are suitable for UP and SMP based clocksources respectively
+ */
+
+#include <linux/interrupt.h>
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/cpu.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/sched_clock.h>
+
+#include <soc/arc/timers.h>
+#include <soc/arc/mcip.h>
+
+
+static unsigned long arc_timer_freq;
+
+static int noinline arc_get_timer_clk(struct device_node *node)
+{
+	struct clk *clk;
+	int ret;
+
+	clk = of_clk_get(node, 0);
+	if (IS_ERR(clk)) {
+		pr_err("timer missing clk\n");
+		return PTR_ERR(clk);
+	}
+
+	ret = clk_prepare_enable(clk);
+	if (ret) {
+		pr_err("Couldn't enable parent clk\n");
+		return ret;
+	}
+
+	arc_timer_freq = clk_get_rate(clk);
+
+	return 0;
+}
+
+/********** Clock Source Device *********/
+
+#ifdef CONFIG_ARC_TIMERS_64BIT
+
+static u64 arc_read_gfrc(struct clocksource *cs)
+{
+	unsigned long flags;
+	u32 l, h;
+
+	/*
+	 * From a programming model pov, there seems to be just one instance of
+	 * MCIP_CMD/MCIP_READBACK however micro-architecturally there's
+	 * an instance PER ARC CORE (not per cluster), and there are dedicated
+	 * hardware decode logic (per core) inside ARConnect to handle
+	 * simultaneous read/write accesses from cores via those two registers.
+	 * So several concurrent commands to ARConnect are OK if they are
+	 * trying to access two different sub-components (like GFRC,
+	 * inter-core interrupt, etc...). HW also supports simultaneously
+	 * accessing GFRC by multiple cores.
+	 * That's why it is safe to disable hard interrupts on the local CPU
+	 * before access to GFRC instead of taking global MCIP spinlock
+	 * defined in arch/arc/kernel/mcip.c
+	 */
+	local_irq_save(flags);
+
+	__mcip_cmd(CMD_GFRC_READ_LO, 0);
+	l = read_aux_reg(ARC_REG_MCIP_READBACK);
+
+	__mcip_cmd(CMD_GFRC_READ_HI, 0);
+	h = read_aux_reg(ARC_REG_MCIP_READBACK);
+
+	local_irq_restore(flags);
+
+	return (((u64)h) << 32) | l;
+}
+
+static notrace u64 arc_gfrc_clock_read(void)
+{
+	return arc_read_gfrc(NULL);
+}
+
+static struct clocksource arc_counter_gfrc = {
+	.name   = "ARConnect GFRC",
+	.rating = 400,
+	.read   = arc_read_gfrc,
+	.mask   = CLOCKSOURCE_MASK(64),
+	.flags  = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int __init arc_cs_setup_gfrc(struct device_node *node)
+{
+	struct mcip_bcr mp;
+	int ret;
+
+	READ_BCR(ARC_REG_MCIP_BCR, mp);
+	if (!mp.gfrc) {
+		pr_warn("Global-64-bit-Ctr clocksource not detected\n");
+		return -ENXIO;
+	}
+
+	ret = arc_get_timer_clk(node);
+	if (ret)
+		return ret;
+
+	sched_clock_register(arc_gfrc_clock_read, 64, arc_timer_freq);
+
+	return clocksource_register_hz(&arc_counter_gfrc, arc_timer_freq);
+}
+TIMER_OF_DECLARE(arc_gfrc, "snps,archs-timer-gfrc", arc_cs_setup_gfrc);
+
+#define AUX_RTC_CTRL	0x103
+#define AUX_RTC_LOW	0x104
+#define AUX_RTC_HIGH	0x105
+
+static u64 arc_read_rtc(struct clocksource *cs)
+{
+	unsigned long status;
+	u32 l, h;
+
+	/*
+	 * hardware has an internal state machine which tracks readout of
+	 * low/high and updates the CTRL.status if
+	 *  - interrupt/exception taken between the two reads
+	 *  - high increments after low has been read
+	 */
+	do {
+		l = read_aux_reg(AUX_RTC_LOW);
+		h = read_aux_reg(AUX_RTC_HIGH);
+		status = read_aux_reg(AUX_RTC_CTRL);
+	} while (!(status & BIT(31)));
+
+	return (((u64)h) << 32) | l;
+}
+
+static notrace u64 arc_rtc_clock_read(void)
+{
+	return arc_read_rtc(NULL);
+}
+
+static struct clocksource arc_counter_rtc = {
+	.name   = "ARCv2 RTC",
+	.rating = 350,
+	.read   = arc_read_rtc,
+	.mask   = CLOCKSOURCE_MASK(64),
+	.flags  = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int __init arc_cs_setup_rtc(struct device_node *node)
+{
+	struct bcr_timer timer;
+	int ret;
+
+	READ_BCR(ARC_REG_TIMERS_BCR, timer);
+	if (!timer.rtc) {
+		pr_warn("Local-64-bit-Ctr clocksource not detected\n");
+		return -ENXIO;
+	}
+
+	/* Local to CPU hence not usable in SMP */
+	if (IS_ENABLED(CONFIG_SMP)) {
+		pr_warn("Local-64-bit-Ctr not usable in SMP\n");
+		return -EINVAL;
+	}
+
+	ret = arc_get_timer_clk(node);
+	if (ret)
+		return ret;
+
+	write_aux_reg(AUX_RTC_CTRL, 1);
+
+	sched_clock_register(arc_rtc_clock_read, 64, arc_timer_freq);
+
+	return clocksource_register_hz(&arc_counter_rtc, arc_timer_freq);
+}
+TIMER_OF_DECLARE(arc_rtc, "snps,archs-timer-rtc", arc_cs_setup_rtc);
+
+#endif
+
+/*
+ * 32bit TIMER1 to keep counting monotonically and wraparound
+ */
+
+static u64 arc_read_timer1(struct clocksource *cs)
+{
+	return (u64) read_aux_reg(ARC_REG_TIMER1_CNT);
+}
+
+static notrace u64 arc_timer1_clock_read(void)
+{
+	return arc_read_timer1(NULL);
+}
+
+static struct clocksource arc_counter_timer1 = {
+	.name   = "ARC Timer1",
+	.rating = 300,
+	.read   = arc_read_timer1,
+	.mask   = CLOCKSOURCE_MASK(32),
+	.flags  = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static int __init arc_cs_setup_timer1(struct device_node *node)
+{
+	int ret;
+
+	/* Local to CPU hence not usable in SMP */
+	if (IS_ENABLED(CONFIG_SMP))
+		return -EINVAL;
+
+	ret = arc_get_timer_clk(node);
+	if (ret)
+		return ret;
+
+	write_aux_reg(ARC_REG_TIMER1_LIMIT, ARC_TIMERN_MAX);
+	write_aux_reg(ARC_REG_TIMER1_CNT, 0);
+	write_aux_reg(ARC_REG_TIMER1_CTRL, TIMER_CTRL_NH);
+
+	sched_clock_register(arc_timer1_clock_read, 32, arc_timer_freq);
+
+	return clocksource_register_hz(&arc_counter_timer1, arc_timer_freq);
+}
+
+/********** Clock Event Device *********/
+
+static int arc_timer_irq;
+
+/*
+ * Arm the timer to interrupt after @cycles
+ * The distinction for oneshot/periodic is done in arc_event_timer_ack() below
+ */
+static void arc_timer_event_setup(unsigned int cycles)
+{
+	write_aux_reg(ARC_REG_TIMER0_LIMIT, cycles);
+	write_aux_reg(ARC_REG_TIMER0_CNT, 0);	/* start from 0 */
+
+	write_aux_reg(ARC_REG_TIMER0_CTRL, TIMER_CTRL_IE | TIMER_CTRL_NH);
+}
+
+
+static int arc_clkevent_set_next_event(unsigned long delta,
+				       struct clock_event_device *dev)
+{
+	arc_timer_event_setup(delta);
+	return 0;
+}
+
+static int arc_clkevent_set_periodic(struct clock_event_device *dev)
+{
+	/*
+	 * At X Hz, 1 sec = 1000ms -> X cycles;
+	 *		      10ms -> X / 100 cycles
+	 */
+	arc_timer_event_setup(arc_timer_freq / HZ);
+	return 0;
+}
+
+static DEFINE_PER_CPU(struct clock_event_device, arc_clockevent_device) = {
+	.name			= "ARC Timer0",
+	.features		= CLOCK_EVT_FEAT_ONESHOT |
+				  CLOCK_EVT_FEAT_PERIODIC,
+	.rating			= 300,
+	.set_next_event		= arc_clkevent_set_next_event,
+	.set_state_periodic	= arc_clkevent_set_periodic,
+};
+
+static irqreturn_t timer_irq_handler(int irq, void *dev_id)
+{
+	/*
+	 * Note that generic IRQ core could have passed @evt for @dev_id if
+	 * irq_set_chip_and_handler() asked for handle_percpu_devid_irq()
+	 */
+	struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
+	int irq_reenable = clockevent_state_periodic(evt);
+
+	/*
+	 * 1. ACK the interrupt
+	 *    - For ARC700, any write to CTRL reg ACKs it, so just rewrite
+	 *      Count when [N]ot [H]alted bit.
+	 *    - For HS3x, it is a bit subtle. On taken count-down interrupt,
+	 *      IP bit [3] is set, which needs to be cleared for ACK'ing.
+	 *      The write below can only update the other two bits, hence
+	 *      explicitly clears IP bit
+	 * 2. Re-arm interrupt if periodic by writing to IE bit [0]
+	 */
+	write_aux_reg(ARC_REG_TIMER0_CTRL, irq_reenable | TIMER_CTRL_NH);
+
+	evt->event_handler(evt);
+
+	return IRQ_HANDLED;
+}
+
+
+static int arc_timer_starting_cpu(unsigned int cpu)
+{
+	struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
+
+	evt->cpumask = cpumask_of(smp_processor_id());
+
+	clockevents_config_and_register(evt, arc_timer_freq, 0, ARC_TIMERN_MAX);
+	enable_percpu_irq(arc_timer_irq, 0);
+	return 0;
+}
+
+static int arc_timer_dying_cpu(unsigned int cpu)
+{
+	disable_percpu_irq(arc_timer_irq);
+	return 0;
+}
+
+/*
+ * clockevent setup for boot CPU
+ */
+static int __init arc_clockevent_setup(struct device_node *node)
+{
+	struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
+	int ret;
+
+	arc_timer_irq = irq_of_parse_and_map(node, 0);
+	if (arc_timer_irq <= 0) {
+		pr_err("clockevent: missing irq\n");
+		return -EINVAL;
+	}
+
+	ret = arc_get_timer_clk(node);
+	if (ret)
+		return ret;
+
+	/* Needs apriori irq_set_percpu_devid() done in intc map function */
+	ret = request_percpu_irq(arc_timer_irq, timer_irq_handler,
+				 "Timer0 (per-cpu-tick)", evt);
+	if (ret) {
+		pr_err("clockevent: unable to request irq\n");
+		return ret;
+	}
+
+	ret = cpuhp_setup_state(CPUHP_AP_ARC_TIMER_STARTING,
+				"clockevents/arc/timer:starting",
+				arc_timer_starting_cpu,
+				arc_timer_dying_cpu);
+	if (ret) {
+		pr_err("Failed to setup hotplug state\n");
+		return ret;
+	}
+	return 0;
+}
+
+static int __init arc_of_timer_init(struct device_node *np)
+{
+	static int init_count = 0;
+	int ret;
+
+	if (!init_count) {
+		init_count = 1;
+		ret = arc_clockevent_setup(np);
+	} else {
+		ret = arc_cs_setup_timer1(np);
+	}
+
+	return ret;
+}
+TIMER_OF_DECLARE(arc_clkevt, "snps,arc-timer", arc_of_timer_init);