clocksource: import ARC timer driver

This adds support for

 - CONFIG_ARC_TIMERS : legacy 32-bit TIMER0 and TIMER1 which count UP
   from @CNT to @LIMIT, before optionally triggering an interrupt.
   These are programmed using ARC auxiliary register interface.
   These are present in all ARC cores (ARC700 and ARC HS38)
   TIMER0 serves as clockevent for all ARC linux builds.
   TIMER1 is used for clocksource in arc700 builds.

 - CONFIG_ARC_TIMERS_64BIT: 64-bit counters, RTC and GFRC found in
   ARC HS38 cores. These are independnet IP blocks with different
   programming model respectively.

Link: http://lkml.kernel.org/r/20161111231132.GA4186@mai
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

2 files changed, 1 insertions, 352 deletions

diff --git a/arch/arc/kernel/Makefile b/arch/arc/kernel/Makefile
index cfcdedf52ff8..8942c5c3b4c5 100644
--- a/arch/arc/kernel/Makefile
+++ b/arch/arc/kernel/Makefile
@@ -8,7 +8,7 @@
 # Pass UTS_MACHINE for user_regset definition
 CFLAGS_ptrace.o		+= -DUTS_MACHINE='"$(UTS_MACHINE)"'
 
-obj-y	:= arcksyms.o setup.o irq.o time.o reset.o ptrace.o process.o devtree.o
+obj-y	:= arcksyms.o setup.o irq.o reset.o ptrace.o process.o devtree.o
 obj-y	+= signal.o traps.o sys.o troubleshoot.o stacktrace.o disasm.o
 obj-$(CONFIG_ISA_ARCOMPACT)		+= entry-compact.o intc-compact.o
 obj-$(CONFIG_ISA_ARCV2)			+= entry-arcv2.o intc-arcv2.o
diff --git a/arch/arc/kernel/time.c b/arch/arc/kernel/time.c
deleted file mode 100644
index 94b9cd169374..000000000000
--- a/arch/arc/kernel/time.c
+++ /dev/null
@@ -1,351 +0,0 @@
-/*
- * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- *
- * vineetg: Jan 1011
- *  -sched_clock( ) no longer jiffies based. Uses the same clocksource
- *   as gtod
- *
- * Rajeshwarr/Vineetg: Mar 2008
- *  -Implemented CONFIG_GENERIC_TIME (rather deleted arch specific code)
- *   for arch independent gettimeofday()
- *  -Implemented CONFIG_GENERIC_CLOCKEVENTS as base for hrtimers
- *
- * Vineetg: Mar 2008: Forked off from time.c which now is time-jiff.c
- */
-
-/* ARC700 has two 32bit independent prog Timers: TIMER0 and TIMER1
- * Each can programmed to go from @count to @limit and optionally
- * interrupt when that happens.
- * A write to Control Register clears the Interrupt
- *
- * We've designated TIMER0 for events (clockevents)
- * while TIMER1 for free running (clocksource)
- *
- * Newer ARC700 cores have 64bit clk fetching RTSC insn, preferred over TIMER1
- * which however is currently broken
- */
-
-#include <linux/interrupt.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 <asm/irq.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");
-		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 cycle_t arc_read_gfrc(struct clocksource *cs)
-{
-	unsigned long flags;
-	u32 l, h;
-
-	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 (((cycle_t)h) << 32) | l;
-}
-
-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");
-		return -ENXIO;
-	}
-
-	ret = arc_get_timer_clk(node);
-	if (ret)
-		return ret;
-
-	return clocksource_register_hz(&arc_counter_gfrc, arc_timer_freq);
-}
-CLOCKSOURCE_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 cycle_t 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 & _BITUL(31)));
-
-	return (((cycle_t)h) << 32) | l;
-}
-
-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");
-		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");
-		return -EINVAL;
-	}
-
-	ret = arc_get_timer_clk(node);
-	if (ret)
-		return ret;
-
-	write_aux_reg(AUX_RTC_CTRL, 1);
-
-	return clocksource_register_hz(&arc_counter_rtc, arc_timer_freq);
-}
-CLOCKSOURCE_OF_DECLARE(arc_rtc, "snps,archs-timer-rtc", arc_cs_setup_rtc);
-
-#endif
-
-/*
- * 32bit TIMER1 to keep counting monotonically and wraparound
- */
-
-static cycle_t arc_read_timer1(struct clocksource *cs)
-{
-	return (cycle_t) read_aux_reg(ARC_REG_TIMER1_CNT);
-}
-
-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);
-
-	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);
-
-	/*
-	 * Any write to CTRL reg ACks the interrupt, we rewrite the
-	 * Count when [N]ot [H]alted bit.
-	 * And re-arm it if perioid by [I]nterrupt [E]nable bit
-	 */
-	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");
-		return -EINVAL;
-	}
-
-	ret = arc_get_timer_clk(node);
-	if (ret) {
-		pr_err("clockevent: missing clk");
-		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,
-				"AP_ARC_TIMER_STARTING",
-				arc_timer_starting_cpu,
-				arc_timer_dying_cpu);
-	if (ret) {
-		pr_err("Failed to setup hotplug state");
-		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;
-}
-CLOCKSOURCE_OF_DECLARE(arc_clkevt, "snps,arc-timer", arc_of_timer_init);