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 u64 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