2 * Copyright (C) 2004, 2007-2010, 2011-2012 Synopsys, Inc. (www.synopsys.com)
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
9 * -sched_clock( ) no longer jiffies based. Uses the same clocksource
12 * Rajeshwarr/Vineetg: Mar 2008
13 * -Implemented CONFIG_GENERIC_TIME (rather deleted arch specific code)
14 * for arch independent gettimeofday()
15 * -Implemented CONFIG_GENERIC_CLOCKEVENTS as base for hrtimers
17 * Vineetg: Mar 2008: Forked off from time.c which now is time-jiff.c
20 /* ARC700 has two 32bit independent prog Timers: TIMER0 and TIMER1
21 * Each can programmed to go from @count to @limit and optionally
22 * interrupt when that happens.
23 * A write to Control Register clears the Interrupt
25 * We've designated TIMER0 for events (clockevents)
26 * while TIMER1 for free running (clocksource)
28 * Newer ARC700 cores have 64bit clk fetching RTSC insn, preferred over TIMER1
29 * which however is currently broken
32 #include <linux/interrupt.h>
33 #include <linux/clk.h>
34 #include <linux/clk-provider.h>
35 #include <linux/clocksource.h>
36 #include <linux/clockchips.h>
37 #include <linux/cpu.h>
39 #include <linux/of_irq.h>
41 #include <asm/arcregs.h>
45 /* Timer related Aux registers */
46 #define ARC_REG_TIMER0_LIMIT 0x23 /* timer 0 limit */
47 #define ARC_REG_TIMER0_CTRL 0x22 /* timer 0 control */
48 #define ARC_REG_TIMER0_CNT 0x21 /* timer 0 count */
49 #define ARC_REG_TIMER1_LIMIT 0x102 /* timer 1 limit */
50 #define ARC_REG_TIMER1_CTRL 0x101 /* timer 1 control */
51 #define ARC_REG_TIMER1_CNT 0x100 /* timer 1 count */
53 #define TIMER_CTRL_IE (1 << 0) /* Interrupt when Count reaches limit */
54 #define TIMER_CTRL_NH (1 << 1) /* Count only when CPU NOT halted */
56 #define ARC_TIMER_MAX 0xFFFFFFFF
58 static unsigned long arc_timer_freq;
60 static int noinline arc_get_timer_clk(struct device_node *node)
65 clk = of_clk_get(node, 0);
67 pr_err("timer missing clk");
71 ret = clk_prepare_enable(clk);
73 pr_err("Couldn't enable parent clk\n");
77 arc_timer_freq = clk_get_rate(clk);
82 /********** Clock Source Device *********/
84 #ifdef CONFIG_ARC_HAS_GFRC
86 static int arc_counter_setup(void)
91 static cycle_t arc_counter_read(struct clocksource *cs)
95 #ifdef CONFIG_CPU_BIG_ENDIAN
103 local_irq_save(flags);
105 __mcip_cmd(CMD_GFRC_READ_LO, 0);
106 stamp.l = read_aux_reg(ARC_REG_MCIP_READBACK);
108 __mcip_cmd(CMD_GFRC_READ_HI, 0);
109 stamp.h = read_aux_reg(ARC_REG_MCIP_READBACK);
111 local_irq_restore(flags);
116 static struct clocksource arc_counter = {
117 .name = "ARConnect GFRC",
119 .read = arc_counter_read,
120 .mask = CLOCKSOURCE_MASK(64),
121 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
126 #ifdef CONFIG_ARC_HAS_RTC
128 #define AUX_RTC_CTRL 0x103
129 #define AUX_RTC_LOW 0x104
130 #define AUX_RTC_HIGH 0x105
132 int arc_counter_setup(void)
134 write_aux_reg(AUX_RTC_CTRL, 1);
136 /* Not usable in SMP */
137 return !IS_ENABLED(CONFIG_SMP);
140 static cycle_t arc_counter_read(struct clocksource *cs)
142 unsigned long status;
144 #ifdef CONFIG_CPU_BIG_ENDIAN
145 struct { u32 high, low; };
147 struct { u32 low, high; };
155 " lr %0, [AUX_RTC_LOW] \n"
156 " lr %1, [AUX_RTC_HIGH] \n"
157 " lr %2, [AUX_RTC_CTRL] \n"
158 " bbit0.nt %2, 31, 1b \n"
159 : "=r" (stamp.low), "=r" (stamp.high), "=r" (status));
164 static struct clocksource arc_counter = {
167 .read = arc_counter_read,
168 .mask = CLOCKSOURCE_MASK(64),
169 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
172 #else /* !CONFIG_ARC_HAS_RTC */
175 * set 32bit TIMER1 to keep counting monotonically and wraparound
177 int arc_counter_setup(void)
179 write_aux_reg(ARC_REG_TIMER1_LIMIT, ARC_TIMER_MAX);
180 write_aux_reg(ARC_REG_TIMER1_CNT, 0);
181 write_aux_reg(ARC_REG_TIMER1_CTRL, TIMER_CTRL_NH);
183 /* Not usable in SMP */
184 return !IS_ENABLED(CONFIG_SMP);
187 static cycle_t arc_counter_read(struct clocksource *cs)
189 return (cycle_t) read_aux_reg(ARC_REG_TIMER1_CNT);
192 static struct clocksource arc_counter = {
193 .name = "ARC Timer1",
195 .read = arc_counter_read,
196 .mask = CLOCKSOURCE_MASK(32),
197 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
203 /********** Clock Event Device *********/
205 static int arc_timer_irq;
208 * Arm the timer to interrupt after @cycles
209 * The distinction for oneshot/periodic is done in arc_event_timer_ack() below
211 static void arc_timer_event_setup(unsigned int cycles)
213 write_aux_reg(ARC_REG_TIMER0_LIMIT, cycles);
214 write_aux_reg(ARC_REG_TIMER0_CNT, 0); /* start from 0 */
216 write_aux_reg(ARC_REG_TIMER0_CTRL, TIMER_CTRL_IE | TIMER_CTRL_NH);
220 static int arc_clkevent_set_next_event(unsigned long delta,
221 struct clock_event_device *dev)
223 arc_timer_event_setup(delta);
227 static int arc_clkevent_set_periodic(struct clock_event_device *dev)
230 * At X Hz, 1 sec = 1000ms -> X cycles;
231 * 10ms -> X / 100 cycles
233 arc_timer_event_setup(arc_timer_freq / HZ);
237 static DEFINE_PER_CPU(struct clock_event_device, arc_clockevent_device) = {
238 .name = "ARC Timer0",
239 .features = CLOCK_EVT_FEAT_ONESHOT |
240 CLOCK_EVT_FEAT_PERIODIC,
242 .set_next_event = arc_clkevent_set_next_event,
243 .set_state_periodic = arc_clkevent_set_periodic,
246 static irqreturn_t timer_irq_handler(int irq, void *dev_id)
249 * Note that generic IRQ core could have passed @evt for @dev_id if
250 * irq_set_chip_and_handler() asked for handle_percpu_devid_irq()
252 struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
253 int irq_reenable = clockevent_state_periodic(evt);
256 * Any write to CTRL reg ACks the interrupt, we rewrite the
257 * Count when [N]ot [H]alted bit.
258 * And re-arm it if perioid by [I]nterrupt [E]nable bit
260 write_aux_reg(ARC_REG_TIMER0_CTRL, irq_reenable | TIMER_CTRL_NH);
262 evt->event_handler(evt);
267 static int arc_timer_cpu_notify(struct notifier_block *self,
268 unsigned long action, void *hcpu)
270 struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
272 evt->cpumask = cpumask_of(smp_processor_id());
274 switch (action & ~CPU_TASKS_FROZEN) {
276 clockevents_config_and_register(evt, arc_timer_freq,
278 enable_percpu_irq(arc_timer_irq, 0);
281 disable_percpu_irq(arc_timer_irq);
288 static struct notifier_block arc_timer_cpu_nb = {
289 .notifier_call = arc_timer_cpu_notify,
293 * clockevent setup for boot CPU
295 static void __init arc_clockevent_setup(struct device_node *node)
297 struct clock_event_device *evt = this_cpu_ptr(&arc_clockevent_device);
300 register_cpu_notifier(&arc_timer_cpu_nb);
302 arc_timer_irq = irq_of_parse_and_map(node, 0);
303 if (arc_timer_irq <= 0)
304 panic("clockevent: missing irq");
306 ret = arc_get_timer_clk(node);
308 panic("clockevent: missing clk");
310 evt->irq = arc_timer_irq;
311 evt->cpumask = cpumask_of(smp_processor_id());
312 clockevents_config_and_register(evt, arc_timer_freq,
315 /* Needs apriori irq_set_percpu_devid() done in intc map function */
316 ret = request_percpu_irq(arc_timer_irq, timer_irq_handler,
317 "Timer0 (per-cpu-tick)", evt);
319 panic("clockevent: unable to request irq\n");
321 enable_percpu_irq(arc_timer_irq, 0);
323 CLOCKSOURCE_OF_DECLARE(arc_clkevt, "snps,arc-timer", arc_clockevent_setup);
326 * Called from start_kernel() - boot CPU only
328 * -Sets up h/w timers as applicable on boot cpu
329 * -Also sets up any global state needed for timer subsystem:
330 * - for "counting" timer, registers a clocksource, usable across CPUs
331 * (provided that underlying counter h/w is synchronized across cores)
333 void __init time_init(void)
339 * sets up the timekeeping free-flowing counter which also returns
340 * whether the counter is usable as clocksource
342 if (arc_counter_setup())
344 * CLK upto 4.29 GHz can be safely represented in 32 bits
345 * because Max 32 bit number is 4,294,967,295
347 clocksource_register_hz(&arc_counter, arc_timer_freq);