1 /* 2 * Copyright (C) 2008 Manuel Lauss <mano@roarinelk.homelinux.net> 3 * 4 * Previous incarnations were: 5 * Copyright (C) 2001, 2006, 2008 MontaVista Software, <source@mvista.com> 6 * Copied and modified Carsten Langgaard's time.c 7 * 8 * Carsten Langgaard, carstenl@mips.com 9 * Copyright (C) 1999,2000 MIPS Technologies, Inc. All rights reserved. 10 * 11 * ######################################################################## 12 * 13 * This program is free software; you can distribute it and/or modify it 14 * under the terms of the GNU General Public License (Version 2) as 15 * published by the Free Software Foundation. 16 * 17 * This program is distributed in the hope it will be useful, but WITHOUT 18 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 19 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 20 * for more details. 21 * 22 * You should have received a copy of the GNU General Public License along 23 * with this program; if not, write to the Free Software Foundation, Inc., 24 * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA. 25 * 26 * ######################################################################## 27 * 28 * Clocksource/event using the 32.768kHz-clocked Counter1 ('RTC' in the 29 * databooks). Firmware/Board init code must enable the counters in the 30 * counter control register, otherwise the CP0 counter clocksource/event 31 * will be installed instead (and use of 'wait' instruction is prohibited). 32 */ 33 34 #include <linux/clockchips.h> 35 #include <linux/clocksource.h> 36 #include <linux/interrupt.h> 37 #include <linux/spinlock.h> 38 39 #include <asm/processor.h> 40 #include <asm/time.h> 41 #include <asm/mach-au1x00/au1000.h> 42 43 /* 32kHz clock enabled and detected */ 44 #define CNTR_OK (SYS_CNTRL_E0 | SYS_CNTRL_32S) 45 46 static cycle_t au1x_counter1_read(struct clocksource *cs) 47 { 48 return au_readl(SYS_RTCREAD); 49 } 50 51 static struct clocksource au1x_counter1_clocksource = { 52 .name = "alchemy-counter1", 53 .read = au1x_counter1_read, 54 .mask = CLOCKSOURCE_MASK(32), 55 .flags = CLOCK_SOURCE_IS_CONTINUOUS, 56 .rating = 100, 57 }; 58 59 static int au1x_rtcmatch2_set_next_event(unsigned long delta, 60 struct clock_event_device *cd) 61 { 62 delta += au_readl(SYS_RTCREAD); 63 /* wait for register access */ 64 while (au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_M21) 65 ; 66 au_writel(delta, SYS_RTCMATCH2); 67 au_sync(); 68 69 return 0; 70 } 71 72 static void au1x_rtcmatch2_set_mode(enum clock_event_mode mode, 73 struct clock_event_device *cd) 74 { 75 } 76 77 static irqreturn_t au1x_rtcmatch2_irq(int irq, void *dev_id) 78 { 79 struct clock_event_device *cd = dev_id; 80 cd->event_handler(cd); 81 return IRQ_HANDLED; 82 } 83 84 static struct clock_event_device au1x_rtcmatch2_clockdev = { 85 .name = "rtcmatch2", 86 .features = CLOCK_EVT_FEAT_ONESHOT, 87 .rating = 100, 88 .irq = AU1000_RTC_MATCH2_INT, 89 .set_next_event = au1x_rtcmatch2_set_next_event, 90 .set_mode = au1x_rtcmatch2_set_mode, 91 .cpumask = cpu_all_mask, 92 }; 93 94 static struct irqaction au1x_rtcmatch2_irqaction = { 95 .handler = au1x_rtcmatch2_irq, 96 .flags = IRQF_DISABLED | IRQF_TIMER, 97 .name = "timer", 98 .dev_id = &au1x_rtcmatch2_clockdev, 99 }; 100 101 void __init plat_time_init(void) 102 { 103 struct clock_event_device *cd = &au1x_rtcmatch2_clockdev; 104 unsigned long t; 105 106 /* Check if firmware (YAMON, ...) has enabled 32kHz and clock 107 * has been detected. If so install the rtcmatch2 clocksource, 108 * otherwise don't bother. Note that both bits being set is by 109 * no means a definite guarantee that the counters actually work 110 * (the 32S bit seems to be stuck set to 1 once a single clock- 111 * edge is detected, hence the timeouts). 112 */ 113 if (CNTR_OK != (au_readl(SYS_COUNTER_CNTRL) & CNTR_OK)) 114 goto cntr_err; 115 116 /* 117 * setup counter 1 (RTC) to tick at full speed 118 */ 119 t = 0xffffff; 120 while ((au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_T1S) && --t) 121 asm volatile ("nop"); 122 if (!t) 123 goto cntr_err; 124 125 au_writel(0, SYS_RTCTRIM); /* 32.768 kHz */ 126 au_sync(); 127 128 t = 0xffffff; 129 while ((au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C1S) && --t) 130 asm volatile ("nop"); 131 if (!t) 132 goto cntr_err; 133 au_writel(0, SYS_RTCWRITE); 134 au_sync(); 135 136 t = 0xffffff; 137 while ((au_readl(SYS_COUNTER_CNTRL) & SYS_CNTRL_C1S) && --t) 138 asm volatile ("nop"); 139 if (!t) 140 goto cntr_err; 141 142 /* register counter1 clocksource and event device */ 143 clocksource_set_clock(&au1x_counter1_clocksource, 32768); 144 clocksource_register(&au1x_counter1_clocksource); 145 146 cd->shift = 32; 147 cd->mult = div_sc(32768, NSEC_PER_SEC, cd->shift); 148 cd->max_delta_ns = clockevent_delta2ns(0xffffffff, cd); 149 cd->min_delta_ns = clockevent_delta2ns(8, cd); /* ~0.25ms */ 150 clockevents_register_device(cd); 151 setup_irq(AU1000_RTC_MATCH2_INT, &au1x_rtcmatch2_irqaction); 152 153 printk(KERN_INFO "Alchemy clocksource installed\n"); 154 155 return; 156 157 cntr_err: 158 /* 159 * MIPS kernel assigns 'au1k_wait' to 'cpu_wait' before this 160 * function is called. Because the Alchemy counters are unusable 161 * the C0 timekeeping code is installed and use of the 'wait' 162 * instruction must be prohibited, which is done most easily by 163 * assigning NULL to cpu_wait. 164 */ 165 cpu_wait = NULL; 166 r4k_clockevent_init(); 167 init_r4k_clocksource(); 168 } 169