drivers/clocksource/timer-ep93xx.c

1 // SPDX-License-Identifier: GPL-2.0
3  * Cirrus Logic EP93xx timer driver.
6  * Based on a rewrite of arch/arm/mach-ep93xx/timer.c:
14 #include <linux/io-64-nonatomic-lo-hi.h>
24  * Timer handling for EP93xx
27  * 3 (32 bit) count down at 508 kHz, are self-reloading, and can generate
28  * an interrupt on underflow.  Timer 4 (40 bit) counts down at 983.04 kHz,
29  * is free-running, and can't generate interrupts.
31  * The 508 kHz timers are ideal for use for the timer interrupt, as the
33  * timer (timer 3) to get as long sleep intervals as possible when using
36  * The higher clock rate of timer 4 makes it a better choice than the
54  * This read-only register contains the low word of the time stamp debug timer
79 	return lo_hi_readq(tcu->base + EP93XX_TIMER4_VALUE_LOW) & GENMASK_ULL(39, 0);  in ep93xx_clocksource_read()
95 	/* Clear timer */  in ep93xx_clkevt_set_next_event()
96 	writel(tmode, tcu->base + EP93XX_TIMER3_CONTROL);  in ep93xx_clkevt_set_next_event()
99 	writel(next, tcu->base + EP93XX_TIMER3_LOAD);  in ep93xx_clkevt_set_next_event()
101 	       tcu->base + EP93XX_TIMER3_CONTROL);  in ep93xx_clkevt_set_next_event()
108 	/* Disable timer */  in ep93xx_clkevt_shutdown()
109 	writel(0, tcu->base + EP93XX_TIMER3_CONTROL);  in ep93xx_clkevt_shutdown()
129 	/* Writing any value clears the timer interrupt */  in ep93xx_timer_interrupt()
130 	writel(1, tcu->base + EP93XX_TIMER3_CLEAR);  in ep93xx_timer_interrupt()
132 	evt->event_handler(evt);  in ep93xx_timer_interrupt()
146 		return -ENOMEM;  in ep93xx_timer_of_init()
148 	tcu->base = of_iomap(np, 0);  in ep93xx_timer_of_init()
149 	if (!tcu->base) {  in ep93xx_timer_of_init()
151 		ret = -ENXIO;  in ep93xx_timer_of_init()
159 		ret = -EINVAL;  in ep93xx_timer_of_init()
160 		pr_err("EP93XX Timer Can't parse IRQ %d", irq);  in ep93xx_timer_of_init()
164 	/* Enable and register clocksource and sched_clock on timer 4 */  in ep93xx_timer_of_init()
166 	       tcu->base + EP93XX_TIMER4_VALUE_HIGH);  in ep93xx_timer_of_init()
173 	/* Set up clockevent on timer 3 */  in ep93xx_timer_of_init()
174 	if (request_irq(irq, ep93xx_timer_interrupt, flags, "ep93xx timer",  in ep93xx_timer_of_init()
176 		pr_err("Failed to request irq %d (ep93xx timer)\n", irq);  in ep93xx_timer_of_init()
189 TIMER_OF_DECLARE(ep93xx_timer, "cirrus,ep9301-timer", ep93xx_timer_of_init);