| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * linux/arch/arm/mach-imx/time.c |
| 3 | * |
| 4 | * Copyright (C) 2000-2001 Deep Blue Solutions |
| 5 | * Copyright (C) 2002 Shane Nay (shane@minirl.com) |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or modify |
| 8 | * it under the terms of the GNU General Public License version 2 as |
| 9 | * published by the Free Software Foundation. |
| 10 | */ |
| 11 | #include <linux/config.h> |
| 12 | #include <linux/kernel.h> |
| 13 | #include <linux/sched.h> |
| 14 | #include <linux/init.h> |
| 15 | #include <linux/interrupt.h> |
| 16 | #include <linux/time.h> |
| 17 | |
| 18 | #include <asm/hardware.h> |
| 19 | #include <asm/io.h> |
| 20 | #include <asm/leds.h> |
| 21 | #include <asm/irq.h> |
| 22 | #include <asm/mach/time.h> |
| 23 | |
| 24 | /* Use timer 1 as system timer */ |
| 25 | #define TIMER_BASE IMX_TIM1_BASE |
| 26 | |
| 27 | /* |
| 28 | * Returns number of us since last clock interrupt. Note that interrupts |
| 29 | * will have been disabled by do_gettimeoffset() |
| 30 | */ |
| 31 | static unsigned long imx_gettimeoffset(void) |
| 32 | { |
| 33 | unsigned long ticks; |
| 34 | |
| 35 | /* |
| 36 | * Get the current number of ticks. Note that there is a race |
| 37 | * condition between us reading the timer and checking for |
| 38 | * an interrupt. We get around this by ensuring that the |
| 39 | * counter has not reloaded between our two reads. |
| 40 | */ |
| 41 | ticks = IMX_TCN(TIMER_BASE); |
| 42 | |
| 43 | /* |
| 44 | * Interrupt pending? If so, we've reloaded once already. |
| 45 | */ |
| 46 | if (IMX_TSTAT(TIMER_BASE) & TSTAT_COMP) |
| 47 | ticks += LATCH; |
| 48 | |
| 49 | /* |
| 50 | * Convert the ticks to usecs |
| 51 | */ |
| 52 | return (1000000 / CLK32) * ticks; |
| 53 | } |
| 54 | |
| 55 | /* |
| 56 | * IRQ handler for the timer |
| 57 | */ |
| 58 | static irqreturn_t |
| 59 | imx_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs) |
| 60 | { |
| 61 | write_seqlock(&xtime_lock); |
| 62 | |
| 63 | /* clear the interrupt */ |
| 64 | if (IMX_TSTAT(TIMER_BASE)) |
| 65 | IMX_TSTAT(TIMER_BASE) = 0; |
| 66 | |
| 67 | timer_tick(regs); |
| 68 | write_sequnlock(&xtime_lock); |
| 69 | |
| 70 | return IRQ_HANDLED; |
| 71 | } |
| 72 | |
| 73 | static struct irqaction imx_timer_irq = { |
| 74 | .name = "i.MX Timer Tick", |
| 75 | .flags = SA_INTERRUPT, |
| 76 | .handler = imx_timer_interrupt |
| 77 | }; |
| 78 | |
| 79 | /* |
| 80 | * Set up timer interrupt, and return the current time in seconds. |
| 81 | */ |
| 82 | static void __init imx_timer_init(void) |
| 83 | { |
| 84 | /* |
| 85 | * Initialise to a known state (all timers off, and timing reset) |
| 86 | */ |
| 87 | IMX_TCTL(TIMER_BASE) = 0; |
| 88 | IMX_TPRER(TIMER_BASE) = 0; |
| 89 | IMX_TCMP(TIMER_BASE) = LATCH - 1; |
| 90 | IMX_TCTL(TIMER_BASE) = TCTL_CLK_32 | TCTL_IRQEN | TCTL_TEN; |
| 91 | |
| 92 | /* |
| 93 | * Make irqs happen for the system timer |
| 94 | */ |
| 95 | setup_irq(TIM1_INT, &imx_timer_irq); |
| 96 | } |
| 97 | |
| 98 | struct sys_timer imx_timer = { |
| 99 | .init = imx_timer_init, |
| 100 | .offset = imx_gettimeoffset, |
| 101 | }; |