| Andrew Scull | b4b6d4a | 2019-01-02 15:54:55 +0000 | [diff] [blame] | 1 | /* |
| 2 | * linux/arch/arm/common/time-acorn.c |
| 3 | * |
| 4 | * Copyright (c) 1996-2000 Russell King. |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or modify |
| 7 | * it under the terms of the GNU General Public License version 2 as |
| 8 | * published by the Free Software Foundation. |
| 9 | * |
| 10 | * Changelog: |
| 11 | * 24-Sep-1996 RMK Created |
| 12 | * 10-Oct-1996 RMK Brought up to date with arch-sa110eval |
| 13 | * 04-Dec-1997 RMK Updated for new arch/arm/time.c |
| 14 | * 13=Jun-2004 DS Moved to arch/arm/common b/c shared w/CLPS7500 |
| 15 | */ |
| 16 | #include <linux/timex.h> |
| 17 | #include <linux/init.h> |
| 18 | #include <linux/interrupt.h> |
| 19 | #include <linux/irq.h> |
| 20 | #include <linux/io.h> |
| 21 | |
| 22 | #include <mach/hardware.h> |
| 23 | #include <asm/hardware/ioc.h> |
| 24 | |
| 25 | #include <asm/mach/time.h> |
| 26 | |
| 27 | #define RPC_CLOCK_FREQ 2000000 |
| 28 | #define RPC_LATCH DIV_ROUND_CLOSEST(RPC_CLOCK_FREQ, HZ) |
| 29 | |
| 30 | static u32 ioc_timer_gettimeoffset(void) |
| 31 | { |
| 32 | unsigned int count1, count2, status; |
| 33 | long offset; |
| 34 | |
| 35 | ioc_writeb (0, IOC_T0LATCH); |
| 36 | barrier (); |
| 37 | count1 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8); |
| 38 | barrier (); |
| 39 | status = ioc_readb(IOC_IRQREQA); |
| 40 | barrier (); |
| 41 | ioc_writeb (0, IOC_T0LATCH); |
| 42 | barrier (); |
| 43 | count2 = ioc_readb(IOC_T0CNTL) | (ioc_readb(IOC_T0CNTH) << 8); |
| 44 | |
| 45 | offset = count2; |
| 46 | if (count2 < count1) { |
| 47 | /* |
| 48 | * We have not had an interrupt between reading count1 |
| 49 | * and count2. |
| 50 | */ |
| 51 | if (status & (1 << 5)) |
| 52 | offset -= RPC_LATCH; |
| 53 | } else if (count2 > count1) { |
| 54 | /* |
| 55 | * We have just had another interrupt between reading |
| 56 | * count1 and count2. |
| 57 | */ |
| 58 | offset -= RPC_LATCH; |
| 59 | } |
| 60 | |
| 61 | offset = (RPC_LATCH - offset) * (tick_nsec / 1000); |
| 62 | return DIV_ROUND_CLOSEST(offset, RPC_LATCH) * 1000; |
| 63 | } |
| 64 | |
| 65 | void __init ioctime_init(void) |
| 66 | { |
| 67 | ioc_writeb(RPC_LATCH & 255, IOC_T0LTCHL); |
| 68 | ioc_writeb(RPC_LATCH >> 8, IOC_T0LTCHH); |
| 69 | ioc_writeb(0, IOC_T0GO); |
| 70 | } |
| 71 | |
| 72 | static irqreturn_t |
| 73 | ioc_timer_interrupt(int irq, void *dev_id) |
| 74 | { |
| 75 | timer_tick(); |
| 76 | return IRQ_HANDLED; |
| 77 | } |
| 78 | |
| 79 | static struct irqaction ioc_timer_irq = { |
| 80 | .name = "timer", |
| 81 | .handler = ioc_timer_interrupt |
| 82 | }; |
| 83 | |
| 84 | /* |
| 85 | * Set up timer interrupt. |
| 86 | */ |
| 87 | void __init ioc_timer_init(void) |
| 88 | { |
| 89 | arch_gettimeoffset = ioc_timer_gettimeoffset; |
| 90 | ioctime_init(); |
| 91 | setup_irq(IRQ_TIMER0, &ioc_timer_irq); |
| 92 | } |