1// SPDX-License-Identifier: GPL-2.0
2/***************************************************************************/
3
4/*
5 *	sltimers.c -- generic ColdFire slice timer support.
6 *
7 *	Copyright (C) 2009-2010, Philippe De Muyter <phdm@macqel.be>
8 *	based on
9 *	timers.c -- generic ColdFire hardware timer support.
10 *	Copyright (C) 1999-2008, Greg Ungerer <gerg@snapgear.com>
11 */
12
13/***************************************************************************/
14
15#include <linux/kernel.h>
16#include <linux/init.h>
17#include <linux/sched.h>
18#include <linux/interrupt.h>
19#include <linux/irq.h>
20#include <linux/profile.h>
21#include <linux/clocksource.h>
22#include <asm/io.h>
23#include <asm/traps.h>
24#include <asm/machdep.h>
25#include <asm/coldfire.h>
26#include <asm/mcfslt.h>
27#include <asm/mcfsim.h>
28
29/***************************************************************************/
30
31#ifdef CONFIG_HIGHPROFILE
32
33/*
34 *	By default use Slice Timer 1 as the profiler clock timer.
35 */
36#define	PA(a)	(MCFSLT_TIMER1 + (a))
37
38/*
39 *	Choose a reasonably fast profile timer. Make it an odd value to
40 *	try and get good coverage of kernel operations.
41 */
42#define	PROFILEHZ	1013
43
44irqreturn_t mcfslt_profile_tick(int irq, void *dummy)
45{
46	/* Reset Slice Timer 1 */
47	__raw_writel(MCFSLT_SSR_BE | MCFSLT_SSR_TE, PA(MCFSLT_SSR));
48	if (current->pid)
49		profile_tick(CPU_PROFILING);
50	return IRQ_HANDLED;
51}
52
53void mcfslt_profile_init(void)
54{
55	int ret;
56
57	printk(KERN_INFO "PROFILE: lodging TIMER 1 @ %dHz as profile timer\n",
58	       PROFILEHZ);
59
60	ret = request_irq(MCF_IRQ_PROFILER, mcfslt_profile_tick, IRQF_TIMER,
61			  "profile timer", NULL);
62	if (ret) {
63		pr_err("Failed to request irq %d (profile timer): %pe\n",
64		       MCF_IRQ_PROFILER, ERR_PTR(ret));
65	}
66
67	/* Set up TIMER 2 as high speed profile clock */
68	__raw_writel(MCF_BUSCLK / PROFILEHZ - 1, PA(MCFSLT_STCNT));
69	__raw_writel(MCFSLT_SCR_RUN | MCFSLT_SCR_IEN | MCFSLT_SCR_TEN,
70								PA(MCFSLT_SCR));
71
72}
73
74#endif	/* CONFIG_HIGHPROFILE */
75
76/***************************************************************************/
77
78/*
79 *	By default use Slice Timer 0 as the system clock timer.
80 */
81#define	TA(a)	(MCFSLT_TIMER0 + (a))
82
83static u32 mcfslt_cycles_per_jiffy;
84static u32 mcfslt_cnt;
85
86static irq_handler_t timer_interrupt;
87
88static irqreturn_t mcfslt_tick(int irq, void *dummy)
89{
90	/* Reset Slice Timer 0 */
91	__raw_writel(MCFSLT_SSR_BE | MCFSLT_SSR_TE, TA(MCFSLT_SSR));
92	mcfslt_cnt += mcfslt_cycles_per_jiffy;
93	return timer_interrupt(irq, dummy);
94}
95
96static u64 mcfslt_read_clk(struct clocksource *cs)
97{
98	unsigned long flags;
99	u32 cycles, scnt;
100
101	local_irq_save(flags);
102	scnt = __raw_readl(TA(MCFSLT_SCNT));
103	cycles = mcfslt_cnt;
104	if (__raw_readl(TA(MCFSLT_SSR)) & MCFSLT_SSR_TE) {
105		cycles += mcfslt_cycles_per_jiffy;
106		scnt = __raw_readl(TA(MCFSLT_SCNT));
107	}
108	local_irq_restore(flags);
109
110	/* subtract because slice timers count down */
111	return cycles + ((mcfslt_cycles_per_jiffy - 1) - scnt);
112}
113
114static struct clocksource mcfslt_clk = {
115	.name	= "slt",
116	.rating	= 250,
117	.read	= mcfslt_read_clk,
118	.mask	= CLOCKSOURCE_MASK(32),
119	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
120};
121
122void hw_timer_init(irq_handler_t handler)
123{
124	int r;
125
126	mcfslt_cycles_per_jiffy = MCF_BUSCLK / HZ;
127	/*
128	 *	The coldfire slice timer (SLT) runs from STCNT to 0 included,
129	 *	then STCNT again and so on.  It counts thus actually
130	 *	STCNT + 1 steps for 1 tick, not STCNT.  So if you want
131	 *	n cycles, initialize STCNT with n - 1.
132	 */
133	__raw_writel(mcfslt_cycles_per_jiffy - 1, TA(MCFSLT_STCNT));
134	__raw_writel(MCFSLT_SCR_RUN | MCFSLT_SCR_IEN | MCFSLT_SCR_TEN,
135								TA(MCFSLT_SCR));
136	/* initialize mcfslt_cnt knowing that slice timers count down */
137	mcfslt_cnt = mcfslt_cycles_per_jiffy;
138
139	timer_interrupt = handler;
140	r = request_irq(MCF_IRQ_TIMER, mcfslt_tick, IRQF_TIMER, "timer", NULL);
141	if (r) {
142		pr_err("Failed to request irq %d (timer): %pe\n", MCF_IRQ_TIMER,
143		       ERR_PTR(r));
144	}
145
146	clocksource_register_hz(&mcfslt_clk, MCF_BUSCLK);
147
148#ifdef CONFIG_HIGHPROFILE
149	mcfslt_profile_init();
150#endif
151}
152