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gerrit-public.fairphone.software / kernel / msm-4.19 / ea49f8ffae6262e8de9a0d3e9fcdd384156c7e05 / . / arch / m68knommu / platform / coldfire / sltimers.c
blob: 0a1b937c3e184a9c19b814f5fd1735e78014d3a5 [file] [log] [blame]
Philippe De Muyterea49f8ff2010-09-20 13:11:11 +0200[diff] [blame^]1/***************************************************************************/
2
3/*
4 * sltimers.c -- generic ColdFire slice timer support.
5 *
6 * Copyright (C) 2009-2010, Philippe De Muyter <phdm@macqel.be>
7 * based on
8 * timers.c -- generic ColdFire hardware timer support.
9 * Copyright (C) 1999-2008, Greg Ungerer <gerg@snapgear.com>
10 */
11
12/***************************************************************************/
13
14#include <linux/kernel.h>
15#include <linux/init.h>
16#include <linux/sched.h>
17#include <linux/interrupt.h>
18#include <linux/irq.h>
19#include <linux/profile.h>
20#include <linux/clocksource.h>
21#include <asm/io.h>
22#include <asm/traps.h>
23#include <asm/machdep.h>
24#include <asm/coldfire.h>
25#include <asm/mcfslt.h>
26#include <asm/mcfsim.h>
27
28/***************************************************************************/
29
30#ifdef CONFIG_HIGHPROFILE
31
32/*
33 * By default use Slice Timer 1 as the profiler clock timer.
34 */
35#define PA(a) (MCF_MBAR + MCFSLT_TIMER1 + (a))
36
37/*
38 * Choose a reasonably fast profile timer. Make it an odd value to
39 * try and get good coverage of kernel operations.
40 */
41#define PROFILEHZ 1013
42
43irqreturn_t mcfslt_profile_tick(int irq, void *dummy)
44{
45 /* Reset Slice Timer 1 */
46 __raw_writel(MCFSLT_SSR_BE | MCFSLT_SSR_TE, PA(MCFSLT_SSR));
47 if (current->pid)
48 profile_tick(CPU_PROFILING);
49 return IRQ_HANDLED;
50}
51
52static struct irqaction mcfslt_profile_irq = {
53 .name = "profile timer",
54 .flags = IRQF_DISABLED | IRQF_TIMER,
55 .handler = mcfslt_profile_tick,
56};
57
58void mcfslt_profile_init(void)
59{
60 printk(KERN_INFO "PROFILE: lodging TIMER 1 @ %dHz as profile timer\n",
61 PROFILEHZ);
62
63 setup_irq(MCF_IRQ_PROFILER, &mcfslt_profile_irq);
64
65 /* Set up TIMER 2 as high speed profile clock */
66 __raw_writel(MCF_BUSCLK / PROFILEHZ - 1, PA(MCFSLT_STCNT));
67 __raw_writel(MCFSLT_SCR_RUN | MCFSLT_SCR_IEN | MCFSLT_SCR_TEN,
68 PA(MCFSLT_SCR));
69
70}
71
72#endif /* CONFIG_HIGHPROFILE */
73
74/***************************************************************************/
75
76/*
77 * By default use Slice Timer 0 as the system clock timer.
78 */
79#define TA(a) (MCF_MBAR + MCFSLT_TIMER0 + (a))
80
81static u32 mcfslt_cycles_per_jiffy;
82static u32 mcfslt_cnt;
83
84static irqreturn_t mcfslt_tick(int irq, void *dummy)
85{
86 /* Reset Slice Timer 0 */
87 __raw_writel(MCFSLT_SSR_BE | MCFSLT_SSR_TE, TA(MCFSLT_SSR));
88 mcfslt_cnt += mcfslt_cycles_per_jiffy;
89 return arch_timer_interrupt(irq, dummy);
90}
91
92static struct irqaction mcfslt_timer_irq = {
93 .name = "timer",
94 .flags = IRQF_DISABLED | IRQF_TIMER,
95 .handler = mcfslt_tick,
96};
97
98static cycle_t mcfslt_read_clk(struct clocksource *cs)
99{
100 unsigned long flags;
101 u32 cycles;
102 u16 scnt;
103
104 local_irq_save(flags);
105 scnt = __raw_readl(TA(MCFSLT_SCNT));
106 cycles = mcfslt_cnt;
107 local_irq_restore(flags);
108
109 /* substract because slice timers count down */
110 return cycles - scnt;
111}
112
113static struct clocksource mcfslt_clk = {
114 .name = "slt",
115 .rating = 250,
116 .read = mcfslt_read_clk,
117 .shift = 20,
118 .mask = CLOCKSOURCE_MASK(32),
119 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
120};
121
122void hw_timer_init(void)
123{
124 mcfslt_cycles_per_jiffy = MCF_BUSCLK / HZ;
125 /*
126 * The coldfire slice timer (SLT) runs from STCNT to 0 included,
127 * then STCNT again and so on. It counts thus actually
128 * STCNT + 1 steps for 1 tick, not STCNT. So if you want
129 * n cycles, initialize STCNT with n - 1.
130 */
131 __raw_writel(mcfslt_cycles_per_jiffy - 1, TA(MCFSLT_STCNT));
132 __raw_writel(MCFSLT_SCR_RUN | MCFSLT_SCR_IEN | MCFSLT_SCR_TEN,
133 TA(MCFSLT_SCR));
134 /* initialize mcfslt_cnt knowing that slice timers count down */
135 mcfslt_cnt = mcfslt_cycles_per_jiffy;
136
137 setup_irq(MCF_IRQ_TIMER, &mcfslt_timer_irq);
138
139 mcfslt_clk.mult = clocksource_hz2mult(MCF_BUSCLK, mcfslt_clk.shift);
140 clocksource_register(&mcfslt_clk);
141
142#ifdef CONFIG_HIGHPROFILE
143 mcfslt_profile_init();
144#endif
145}