[mirror_ubuntu-jammy-kernel.git] / arch / arm / mach-rpc / time.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 *  linux/arch/arm/common/time-acorn.c
 *
 *  Copyright (c) 1996-2000 Russell King.
 *
 *  Changelog:
 *   24-Sep-1996	RMK	Created
 *   10-Oct-1996	RMK	Brought up to date with arch-sa110eval
 *   04-Dec-1997	RMK	Updated for new arch/arm/time.c
 *   13=Jun-2004	DS	Moved to arch/arm/common b/c shared w/CLPS7500
 */
#include <linux/clocksource.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/io.h>

#include <mach/hardware.h>
#include <asm/hardware/ioc.h>

#include <asm/mach/time.h>

#define RPC_CLOCK_FREQ 2000000
#define RPC_LATCH DIV_ROUND_CLOSEST(RPC_CLOCK_FREQ, HZ)

static u32 ioc_time;

static u64 ioc_timer_read(struct clocksource *cs)
{
	unsigned int count1, count2, status;
	unsigned long flags;
	u32 ticks;

	local_irq_save(flags);
	ioc_writeb (0, IOC_T0LATCH);
	barrier ();
	count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
	barrier ();
	status = ioc_readb(IOC_IRQREQA);
	barrier ();
	ioc_writeb (0, IOC_T0LATCH);
	barrier ();
	count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8);
	ticks = ioc_time + RPC_LATCH - count2;
	local_irq_restore(flags);

	if (count2 < count1) {
		/*
		 * The timer has not reloaded between reading count1 and
		 * count2, check whether an interrupt was actually pending.
		 */
		if (status & (1 << 5))
			ticks += RPC_LATCH;
	} else if (count2 > count1) {
		/*
		 * The timer has reloaded, so count2 indicates the new
		 * count since the wrap.  The interrupt would not have
		 * been processed, so add the missed ticks.
		 */
		ticks += RPC_LATCH;
	}

	return ticks;
}

static struct clocksource ioctime_clocksource = {
	.read = ioc_timer_read,
	.mask = CLOCKSOURCE_MASK(32),
	.rating = 100,
};

void __init ioctime_init(void)
{
	ioc_writeb(RPC_LATCH & 255, IOC_T0LTCHL);
	ioc_writeb(RPC_LATCH >> 8, IOC_T0LTCHH);
	ioc_writeb(0, IOC_T0GO);
}

static irqreturn_t
ioc_timer_interrupt(int irq, void *dev_id)
{
	ioc_time += RPC_LATCH;
	legacy_timer_tick(1);
	return IRQ_HANDLED;
}

/*
 * Set up timer interrupt.
 */
void __init ioc_timer_init(void)
{
	WARN_ON(clocksource_register_hz(&ioctime_clocksource, RPC_CLOCK_FREQ));
	ioctime_init();
	if (request_irq(IRQ_TIMER0, ioc_timer_interrupt, 0, "timer", NULL))
		pr_err("Failed to request irq %d (timer)\n", IRQ_TIMER0);
}
Commit	Line	Data
d2912cb1	1	// SPDX-License-Identifier: GPL-2.0-only
1da177e4 LT	2	/*
	3	* linux/arch/arm/common/time-acorn.c
	4	*
	5	* Copyright (c) 1996-2000 Russell King.
	6	*
1da177e4 LT	7	* Changelog:
	8	* 24-Sep-1996 RMK Created
	9	* 10-Oct-1996 RMK Brought up to date with arch-sa110eval
	10	* 04-Dec-1997 RMK Updated for new arch/arm/time.c
	11	* 13=Jun-2004 DS Moved to arch/arm/common b/c shared w/CLPS7500
	12	*/
a44c1d70	13	#include <linux/clocksource.h>
1da177e4 LT	14	#include <linux/init.h>
1da177e4 LT	15	#include <linux/interrupt.h>
c4bfa28a	16	#include <linux/irq.h>
fced80c7	17	#include <linux/io.h>
1da177e4	18
a09e64fb	19	#include <mach/hardware.h>
1da177e4 LT	20	#include <asm/hardware/ioc.h>
	21
	22	#include <asm/mach/time.h>
	23
53985371 UKK	24	#define RPC_CLOCK_FREQ 2000000
	25	#define RPC_LATCH DIV_ROUND_CLOSEST(RPC_CLOCK_FREQ, HZ)
	26
a44c1d70 RK	27	static u32 ioc_time;
	28
	29	static u64 ioc_timer_read(struct clocksource *cs)
1da177e4 LT	30	{
1da177e4 LT	31	unsigned int count1, count2, status;
a44c1d70 RK	32	unsigned long flags;
a44c1d70 RK	33	u32 ticks;
1da177e4	34
a44c1d70	35	local_irq_save(flags);
1da177e4 LT	36	ioc_writeb (0, IOC_T0LATCH);
	37	barrier ();
	38	count1 = ioc_readb(IOC_T0CNTL) \| (ioc_readb(IOC_T0CNTH) << 8);
	39	barrier ();
	40	status = ioc_readb(IOC_IRQREQA);
	41	barrier ();
	42	ioc_writeb (0, IOC_T0LATCH);
	43	barrier ();
	44	count2 = ioc_readb(IOC_T0CNTL) \| (ioc_readb(IOC_T0CNTH) << 8);
a44c1d70 RK	45	ticks = ioc_time + RPC_LATCH - count2;
a44c1d70 RK	46	local_irq_restore(flags);
1da177e4	47
1da177e4 LT	48	if (count2 < count1) {
1da177e4 LT	49	/*
a44c1d70 RK	50	* The timer has not reloaded between reading count1 and
a44c1d70 RK	51	* count2, check whether an interrupt was actually pending.
1da177e4 LT	52	*/
1da177e4 LT	53	if (status & (1 << 5))
a44c1d70	54	ticks += RPC_LATCH;
1da177e4 LT	55	} else if (count2 > count1) {
1da177e4 LT	56	/*
a44c1d70 RK	57	* The timer has reloaded, so count2 indicates the new
	58	* count since the wrap. The interrupt would not have
	59	* been processed, so add the missed ticks.
1da177e4	60	*/
a44c1d70	61	ticks += RPC_LATCH;
1da177e4 LT	62	}
1da177e4 LT	63
a44c1d70	64	return ticks;
1da177e4 LT	65	}
1da177e4 LT	66
a44c1d70 RK	67	static struct clocksource ioctime_clocksource = {
	68	.read = ioc_timer_read,
	69	.mask = CLOCKSOURCE_MASK(32),
	70	.rating = 100,
	71	};
	72
1da177e4 LT	73	void __init ioctime_init(void)
1da177e4 LT	74	{
53985371 UKK	75	ioc_writeb(RPC_LATCH & 255, IOC_T0LTCHL);
53985371 UKK	76	ioc_writeb(RPC_LATCH >> 8, IOC_T0LTCHH);
1da177e4 LT	77	ioc_writeb(0, IOC_T0GO);
	78	}
	79
	80	static irqreturn_t
0cd61b68	81	ioc_timer_interrupt(int irq, void *dev_id)
1da177e4	82	{
a44c1d70	83	ioc_time += RPC_LATCH;
6239da29	84	legacy_timer_tick(1);
1da177e4 LT	85	return IRQ_HANDLED;
	86	}
	87
1da177e4 LT	88	/*
	89	* Set up timer interrupt.
	90	*/
6bb27d73	91	void __init ioc_timer_init(void)
1da177e4	92	{
a44c1d70	93	WARN_ON(clocksource_register_hz(&ioctime_clocksource, RPC_CLOCK_FREQ));
1da177e4	94	ioctime_init();
575fb69e	95	if (request_irq(IRQ_TIMER0, ioc_timer_interrupt, 0, "timer", NULL))
575fb69e	96	pr_err("Failed to request irq %d (timer)\n", IRQ_TIMER0);
1da177e4	97	}