xref: /linux/arch/m68k/coldfire/pit.c (revision f9a01539)
1 // SPDX-License-Identifier: GPL-2.0
2 /***************************************************************************/
3 
4 /*
5  *	pit.c -- Freescale ColdFire PIT timer. Currently this type of
6  *	         hardware timer only exists in the Freescale ColdFire
7  *		 5270/5271, 5282 and 5208 CPUs. No doubt newer ColdFire
8  *		 family members will probably use it too.
9  *
10  *	Copyright (C) 1999-2008, Greg Ungerer (gerg@snapgear.com)
11  *	Copyright (C) 2001-2004, SnapGear Inc. (www.snapgear.com)
12  */
13 
14 /***************************************************************************/
15 
16 #include <linux/kernel.h>
17 #include <linux/sched.h>
18 #include <linux/param.h>
19 #include <linux/init.h>
20 #include <linux/interrupt.h>
21 #include <linux/irq.h>
22 #include <linux/clockchips.h>
23 #include <asm/machdep.h>
24 #include <asm/io.h>
25 #include <asm/coldfire.h>
26 #include <asm/mcfpit.h>
27 #include <asm/mcfsim.h>
28 
29 /***************************************************************************/
30 
31 /*
32  *	By default use timer1 as the system clock timer.
33  */
34 #define	FREQ	((MCF_CLK / 2) / 64)
35 #define	TA(a)	(MCFPIT_BASE1 + (a))
36 #define PIT_CYCLES_PER_JIFFY (FREQ / HZ)
37 
38 static u32 pit_cnt;
39 
40 /*
41  * Initialize the PIT timer.
42  *
43  * This is also called after resume to bring the PIT into operation again.
44  */
45 
cf_pit_set_periodic(struct clock_event_device * evt)46 static int cf_pit_set_periodic(struct clock_event_device *evt)
47 {
48 	__raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
49 	__raw_writew(PIT_CYCLES_PER_JIFFY, TA(MCFPIT_PMR));
50 	__raw_writew(MCFPIT_PCSR_EN | MCFPIT_PCSR_PIE |
51 		     MCFPIT_PCSR_OVW | MCFPIT_PCSR_RLD |
52 		     MCFPIT_PCSR_CLK64, TA(MCFPIT_PCSR));
53 	return 0;
54 }
55 
cf_pit_set_oneshot(struct clock_event_device * evt)56 static int cf_pit_set_oneshot(struct clock_event_device *evt)
57 {
58 	__raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
59 	__raw_writew(MCFPIT_PCSR_EN | MCFPIT_PCSR_PIE |
60 		     MCFPIT_PCSR_OVW | MCFPIT_PCSR_CLK64, TA(MCFPIT_PCSR));
61 	return 0;
62 }
63 
cf_pit_shutdown(struct clock_event_device * evt)64 static int cf_pit_shutdown(struct clock_event_device *evt)
65 {
66 	__raw_writew(MCFPIT_PCSR_DISABLE, TA(MCFPIT_PCSR));
67 	return 0;
68 }
69 
70 /*
71  * Program the next event in oneshot mode
72  *
73  * Delta is given in PIT ticks
74  */
cf_pit_next_event(unsigned long delta,struct clock_event_device * evt)75 static int cf_pit_next_event(unsigned long delta,
76 		struct clock_event_device *evt)
77 {
78 	__raw_writew(delta, TA(MCFPIT_PMR));
79 	return 0;
80 }
81 
82 struct clock_event_device cf_pit_clockevent = {
83 	.name			= "pit",
84 	.features		= CLOCK_EVT_FEAT_PERIODIC |
85 				  CLOCK_EVT_FEAT_ONESHOT,
86 	.set_state_shutdown	= cf_pit_shutdown,
87 	.set_state_periodic	= cf_pit_set_periodic,
88 	.set_state_oneshot	= cf_pit_set_oneshot,
89 	.set_next_event		= cf_pit_next_event,
90 	.shift			= 32,
91 	.irq			= MCF_IRQ_PIT1,
92 };
93 
94 
95 
96 /***************************************************************************/
97 
pit_tick(int irq,void * dummy)98 static irqreturn_t pit_tick(int irq, void *dummy)
99 {
100 	struct clock_event_device *evt = &cf_pit_clockevent;
101 	u16 pcsr;
102 
103 	/* Reset the ColdFire timer */
104 	pcsr = __raw_readw(TA(MCFPIT_PCSR));
105 	__raw_writew(pcsr | MCFPIT_PCSR_PIF, TA(MCFPIT_PCSR));
106 
107 	pit_cnt += PIT_CYCLES_PER_JIFFY;
108 	evt->event_handler(evt);
109 	return IRQ_HANDLED;
110 }
111 
112 /***************************************************************************/
113 
pit_read_clk(struct clocksource * cs)114 static u64 pit_read_clk(struct clocksource *cs)
115 {
116 	unsigned long flags;
117 	u32 cycles;
118 	u16 pcntr;
119 
120 	local_irq_save(flags);
121 	pcntr = __raw_readw(TA(MCFPIT_PCNTR));
122 	cycles = pit_cnt;
123 	local_irq_restore(flags);
124 
125 	return cycles + PIT_CYCLES_PER_JIFFY - pcntr;
126 }
127 
128 /***************************************************************************/
129 
130 static struct clocksource pit_clk = {
131 	.name	= "pit",
132 	.rating	= 100,
133 	.read	= pit_read_clk,
134 	.mask	= CLOCKSOURCE_MASK(32),
135 };
136 
137 /***************************************************************************/
138 
hw_timer_init(void)139 void hw_timer_init(void)
140 {
141 	int ret;
142 
143 	cf_pit_clockevent.cpumask = cpumask_of(smp_processor_id());
144 	cf_pit_clockevent.mult = div_sc(FREQ, NSEC_PER_SEC, 32);
145 	cf_pit_clockevent.max_delta_ns =
146 		clockevent_delta2ns(0xFFFF, &cf_pit_clockevent);
147 	cf_pit_clockevent.max_delta_ticks = 0xFFFF;
148 	cf_pit_clockevent.min_delta_ns =
149 		clockevent_delta2ns(0x3f, &cf_pit_clockevent);
150 	cf_pit_clockevent.min_delta_ticks = 0x3f;
151 	clockevents_register_device(&cf_pit_clockevent);
152 
153 	ret = request_irq(MCF_IRQ_PIT1, pit_tick, IRQF_TIMER, "timer", NULL);
154 	if (ret) {
155 		pr_err("Failed to request irq %d (timer): %pe\n", MCF_IRQ_PIT1,
156 		       ERR_PTR(ret));
157 	}
158 
159 	clocksource_register_hz(&pit_clk, FREQ);
160 }
161 
162 /***************************************************************************/
163