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Linux/arch/m68k/coldfire/sltimers.c

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  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)   (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 
 43 irqreturn_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 
 52 static struct irqaction mcfslt_profile_irq = {
 53         .name    = "profile timer",
 54         .flags   = IRQF_TIMER,
 55         .handler = mcfslt_profile_tick,
 56 };
 57 
 58 void 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)   (MCFSLT_TIMER0 + (a))
 80 
 81 static u32 mcfslt_cycles_per_jiffy;
 82 static u32 mcfslt_cnt;
 83 
 84 static irq_handler_t timer_interrupt;
 85 
 86 static irqreturn_t mcfslt_tick(int irq, void *dummy)
 87 {
 88         /* Reset Slice Timer 0 */
 89         __raw_writel(MCFSLT_SSR_BE | MCFSLT_SSR_TE, TA(MCFSLT_SSR));
 90         mcfslt_cnt += mcfslt_cycles_per_jiffy;
 91         return timer_interrupt(irq, dummy);
 92 }
 93 
 94 static struct irqaction mcfslt_timer_irq = {
 95         .name    = "timer",
 96         .flags   = IRQF_TIMER,
 97         .handler = mcfslt_tick,
 98 };
 99 
100 static cycle_t mcfslt_read_clk(struct clocksource *cs)
101 {
102         unsigned long flags;
103         u32 cycles, scnt;
104 
105         local_irq_save(flags);
106         scnt = __raw_readl(TA(MCFSLT_SCNT));
107         cycles = mcfslt_cnt;
108         if (__raw_readl(TA(MCFSLT_SSR)) & MCFSLT_SSR_TE) {
109                 cycles += mcfslt_cycles_per_jiffy;
110                 scnt = __raw_readl(TA(MCFSLT_SCNT));
111         }
112         local_irq_restore(flags);
113 
114         /* subtract because slice timers count down */
115         return cycles + ((mcfslt_cycles_per_jiffy - 1) - scnt);
116 }
117 
118 static struct clocksource mcfslt_clk = {
119         .name   = "slt",
120         .rating = 250,
121         .read   = mcfslt_read_clk,
122         .mask   = CLOCKSOURCE_MASK(32),
123         .flags  = CLOCK_SOURCE_IS_CONTINUOUS,
124 };
125 
126 void hw_timer_init(irq_handler_t handler)
127 {
128         mcfslt_cycles_per_jiffy = MCF_BUSCLK / HZ;
129         /*
130          *      The coldfire slice timer (SLT) runs from STCNT to 0 included,
131          *      then STCNT again and so on.  It counts thus actually
132          *      STCNT + 1 steps for 1 tick, not STCNT.  So if you want
133          *      n cycles, initialize STCNT with n - 1.
134          */
135         __raw_writel(mcfslt_cycles_per_jiffy - 1, TA(MCFSLT_STCNT));
136         __raw_writel(MCFSLT_SCR_RUN | MCFSLT_SCR_IEN | MCFSLT_SCR_TEN,
137                                                                 TA(MCFSLT_SCR));
138         /* initialize mcfslt_cnt knowing that slice timers count down */
139         mcfslt_cnt = mcfslt_cycles_per_jiffy;
140 
141         timer_interrupt = handler;
142         setup_irq(MCF_IRQ_TIMER, &mcfslt_timer_irq);
143 
144         clocksource_register_hz(&mcfslt_clk, MCF_BUSCLK);
145 
146 #ifdef CONFIG_HIGHPROFILE
147         mcfslt_profile_init();
148 #endif
149 }
150 

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