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 44 irqreturn_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 53 void 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 83 static u32 mcfslt_cycles_per_jiffy; 84 static u32 mcfslt_cnt; 85 86 static irq_handler_t timer_interrupt; 87 88 static 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 96 static 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 } 113 114 static 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 }; 121 122 void 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