time.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Time related functions for Hexagon architecture
  4 *
  5 * Copyright (c) 2010-2011, The Linux Foundation. All rights reserved.
  6 */
  7
  8#include <linux/init.h>
  9#include <linux/clockchips.h>
 10#include <linux/clocksource.h>
 11#include <linux/interrupt.h>
 12#include <linux/err.h>
 13#include <linux/platform_device.h>
 14#include <linux/ioport.h>
 15#include <linux/of.h>
 16#include <linux/of_address.h>
 17#include <linux/of_irq.h>
 18#include <linux/module.h>
 19
 20#include <asm/delay.h>
 21#include <asm/hexagon_vm.h>
 22#include <asm/time.h>
 23
 24#define TIMER_ENABLE		BIT(0)
 25
 26/*
 27 * For the clocksource we need:
 28 *	pcycle frequency (600MHz)
 29 * For the loops_per_jiffy we need:
 30 *	thread/cpu frequency (100MHz)
 31 * And for the timer, we need:
 32 *	sleep clock rate
 33 */
 34
 35cycles_t	pcycle_freq_mhz;
 36cycles_t	thread_freq_mhz;
 37cycles_t	sleep_clk_freq;
 38
 39/*
 40 * 8x50 HDD Specs 5-8.  Simulator co-sim not fixed until
 41 * release 1.1, and then it's "adjustable" and probably not defaulted.
 42 */
 43#define RTOS_TIMER_INT		3
 44#define RTOS_TIMER_REGS_ADDR	0xAB000000UL
 45
 46static struct resource rtos_timer_resources[] = {
 47	{
 48		.start	= RTOS_TIMER_REGS_ADDR,
 49		.end	= RTOS_TIMER_REGS_ADDR+PAGE_SIZE-1,
 50		.flags	= IORESOURCE_MEM,
 51	},
 52};
 53
 54static struct platform_device rtos_timer_device = {
 55	.name		= "rtos_timer",
 56	.id		= -1,
 57	.num_resources	= ARRAY_SIZE(rtos_timer_resources),
 58	.resource	= rtos_timer_resources,
 59};
 60
 61/*  A lot of this stuff should move into a platform specific section.  */
 62struct adsp_hw_timer_struct {
 63	u32 match;   /*  Match value  */
 64	u32 count;
 65	u32 enable;  /*  [1] - CLR_ON_MATCH_EN, [0] - EN  */
 66	u32 clear;   /*  one-shot register that clears the count  */
 67};
 68
 69/*  Look for "TCX0" for related constants.  */
 70static __iomem struct adsp_hw_timer_struct *rtos_timer;
 71
 72static u64 timer_get_cycles(struct clocksource *cs)
 73{
 74	return (u64) __vmgettime();
 75}
 76
 77static struct clocksource hexagon_clocksource = {
 78	.name		= "pcycles",
 79	.rating		= 250,
 80	.read		= timer_get_cycles,
 81	.mask		= CLOCKSOURCE_MASK(64),
 82	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
 83};
 84
 85static int set_next_event(unsigned long delta, struct clock_event_device *evt)
 86{
 87	/*  Assuming the timer will be disabled when we enter here.  */
 88
 89	iowrite32(1, &rtos_timer->clear);
 90	iowrite32(0, &rtos_timer->clear);
 91
 92	iowrite32(delta, &rtos_timer->match);
 93	iowrite32(TIMER_ENABLE, &rtos_timer->enable);
 94	return 0;
 95}
 96
 97#ifdef CONFIG_SMP
 98/*  Broadcast mechanism  */
 99static void broadcast(const struct cpumask *mask)
100{
101	send_ipi(mask, IPI_TIMER);
102}
103#endif
104
105/* XXX Implement set_state_shutdown() */
106static struct clock_event_device hexagon_clockevent_dev = {
107	.name		= "clockevent",
108	.features	= CLOCK_EVT_FEAT_ONESHOT,
109	.rating		= 400,
110	.irq		= RTOS_TIMER_INT,
111	.set_next_event = set_next_event,
112#ifdef CONFIG_SMP
113	.broadcast	= broadcast,
114#endif
115};
116
117#ifdef CONFIG_SMP
118static DEFINE_PER_CPU(struct clock_event_device, clock_events);
119
120void setup_percpu_clockdev(void)
121{
122	int cpu = smp_processor_id();
123	struct clock_event_device *ce_dev = &hexagon_clockevent_dev;
124	struct clock_event_device *dummy_clock_dev =
125		&per_cpu(clock_events, cpu);
126
127	memcpy(dummy_clock_dev, ce_dev, sizeof(*dummy_clock_dev));
128	INIT_LIST_HEAD(&dummy_clock_dev->list);
129
130	dummy_clock_dev->features = CLOCK_EVT_FEAT_DUMMY;
131	dummy_clock_dev->cpumask = cpumask_of(cpu);
132
133	clockevents_register_device(dummy_clock_dev);
134}
135
136/*  Called from smp.c for each CPU's timer ipi call  */
137void ipi_timer(void)
138{
139	int cpu = smp_processor_id();
140	struct clock_event_device *ce_dev = &per_cpu(clock_events, cpu);
141
142	ce_dev->event_handler(ce_dev);
143}
144#endif /* CONFIG_SMP */
145
146static irqreturn_t timer_interrupt(int irq, void *devid)
147{
148	struct clock_event_device *ce_dev = &hexagon_clockevent_dev;
149
150	iowrite32(0, &rtos_timer->enable);
151	ce_dev->event_handler(ce_dev);
152
153	return IRQ_HANDLED;
154}
155
156/*
157 * time_init_deferred - called by start_kernel to set up timer/clock source
158 *
159 * Install the IRQ handler for the clock, setup timers.
160 * This is done late, as that way, we can use ioremap().
161 *
162 * This runs just before the delay loop is calibrated, and
163 * is used for delay calibration.
164 */
165static void __init time_init_deferred(void)
166{
167	struct resource *resource = NULL;
168	struct clock_event_device *ce_dev = &hexagon_clockevent_dev;
169	unsigned long flag = IRQF_TIMER | IRQF_TRIGGER_RISING;
170
171	ce_dev->cpumask = cpu_all_mask;
172
173	resource = rtos_timer_device.resource;
174
175	/*  ioremap here means this has to run later, after paging init  */
176	rtos_timer = ioremap(resource->start, resource_size(resource));
177
178	if (!rtos_timer) {
179		release_mem_region(resource->start, resource_size(resource));
180	}
181	clocksource_register_khz(&hexagon_clocksource, pcycle_freq_mhz * 1000);
182
183	/*  Note: the sim generic RTOS clock is apparently really 18750Hz  */
184
185	/*
186	 * Last arg is some guaranteed seconds for which the conversion will
187	 * work without overflow.
188	 */
189	clockevents_calc_mult_shift(ce_dev, sleep_clk_freq, 4);
190
191	ce_dev->max_delta_ns = clockevent_delta2ns(0x7fffffff, ce_dev);
192	ce_dev->max_delta_ticks = 0x7fffffff;
193	ce_dev->min_delta_ns = clockevent_delta2ns(0xf, ce_dev);
194	ce_dev->min_delta_ticks = 0xf;
195
196#ifdef CONFIG_SMP
197	setup_percpu_clockdev();
198#endif
199
200	clockevents_register_device(ce_dev);
201	if (request_irq(ce_dev->irq, timer_interrupt, flag, "rtos_timer", NULL))
202		pr_err("Failed to register rtos_timer interrupt\n");
203}
204
205void __init time_init(void)
206{
207	late_time_init = time_init_deferred;
208}
209
210void __delay(unsigned long cycles)
211{
212	unsigned long long start = __vmgettime();
213
214	while ((__vmgettime() - start) < cycles)
215		cpu_relax();
216}
217EXPORT_SYMBOL(__delay);
218
219/*
220 * This could become parametric or perhaps even computed at run-time,
221 * but for now we take the observed simulator jitter.
222 */
223static long long fudgefactor = 350;  /* Maybe lower if kernel optimized. */
224
225void __udelay(unsigned long usecs)
226{
227	unsigned long long start = __vmgettime();
228	unsigned long long finish = (pcycle_freq_mhz * usecs) - fudgefactor;
229
230	while ((__vmgettime() - start) < finish)
231		cpu_relax(); /*  not sure how this improves readability  */
232}
233EXPORT_SYMBOL(__udelay);