From 2c3c1048746a4622d8c89a29670120dc8fab93c4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 20:49:45 +0200 Subject: Adding upstream version 6.1.76. Signed-off-by: Daniel Baumann --- arch/openrisc/kernel/time.c | 177 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 177 insertions(+) create mode 100644 arch/openrisc/kernel/time.c (limited to 'arch/openrisc/kernel/time.c') diff --git a/arch/openrisc/kernel/time.c b/arch/openrisc/kernel/time.c new file mode 100644 index 000000000..8e26c1af5 --- /dev/null +++ b/arch/openrisc/kernel/time.c @@ -0,0 +1,177 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * OpenRISC time.c + * + * Linux architectural port borrowing liberally from similar works of + * others. All original copyrights apply as per the original source + * declaration. + * + * Modifications for the OpenRISC architecture: + * Copyright (C) 2010-2011 Jonas Bonn + */ + +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include + +#include +#include + +/* Test the timer ticks to count, used in sync routine */ +inline void openrisc_timer_set(unsigned long count) +{ + mtspr(SPR_TTCR, count); +} + +/* Set the timer to trigger in delta cycles */ +inline void openrisc_timer_set_next(unsigned long delta) +{ + u32 c; + + /* Read 32-bit counter value, add delta, mask off the low 28 bits. + * We're guaranteed delta won't be bigger than 28 bits because the + * generic timekeeping code ensures that for us. + */ + c = mfspr(SPR_TTCR); + c += delta; + c &= SPR_TTMR_TP; + + /* Set counter and enable interrupt. + * Keep timer in continuous mode always. + */ + mtspr(SPR_TTMR, SPR_TTMR_CR | SPR_TTMR_IE | c); +} + +static int openrisc_timer_set_next_event(unsigned long delta, + struct clock_event_device *dev) +{ + openrisc_timer_set_next(delta); + return 0; +} + +/* This is the clock event device based on the OR1K tick timer. + * As the timer is being used as a continuous clock-source (required for HR + * timers) we cannot enable the PERIODIC feature. The tick timer can run using + * one-shot events, so no problem. + */ +static DEFINE_PER_CPU(struct clock_event_device, clockevent_openrisc_timer); + +void openrisc_clockevent_init(void) +{ + unsigned int cpu = smp_processor_id(); + struct clock_event_device *evt = + &per_cpu(clockevent_openrisc_timer, cpu); + struct cpuinfo_or1k *cpuinfo = &cpuinfo_or1k[cpu]; + + mtspr(SPR_TTMR, SPR_TTMR_CR); + +#ifdef CONFIG_SMP + evt->broadcast = tick_broadcast; +#endif + evt->name = "openrisc_timer_clockevent", + evt->features = CLOCK_EVT_FEAT_ONESHOT, + evt->rating = 300, + evt->set_next_event = openrisc_timer_set_next_event, + + evt->cpumask = cpumask_of(cpu); + + /* We only have 28 bits */ + clockevents_config_and_register(evt, cpuinfo->clock_frequency, + 100, 0x0fffffff); + +} + +static inline void timer_ack(void) +{ + /* Clear the IP bit and disable further interrupts */ + /* This can be done very simply... we just need to keep the timer + running, so just maintain the CR bits while clearing the rest + of the register + */ + mtspr(SPR_TTMR, SPR_TTMR_CR); +} + +/* + * The timer interrupt is mostly handled in generic code nowadays... this + * function just acknowledges the interrupt and fires the event handler that + * has been set on the clockevent device by the generic time management code. + * + * This function needs to be called by the timer exception handler and that's + * all the exception handler needs to do. + */ + +irqreturn_t __irq_entry timer_interrupt(struct pt_regs *regs) +{ + struct pt_regs *old_regs = set_irq_regs(regs); + unsigned int cpu = smp_processor_id(); + struct clock_event_device *evt = + &per_cpu(clockevent_openrisc_timer, cpu); + + timer_ack(); + + /* + * update_process_times() expects us to have called irq_enter(). + */ + irq_enter(); + evt->event_handler(evt); + irq_exit(); + + set_irq_regs(old_regs); + + return IRQ_HANDLED; +} + +/* + * Clocksource: Based on OpenRISC timer/counter + * + * This sets up the OpenRISC Tick Timer as a clock source. The tick timer + * is 32 bits wide and runs at the CPU clock frequency. + */ +static u64 openrisc_timer_read(struct clocksource *cs) +{ + return (u64) mfspr(SPR_TTCR); +} + +static struct clocksource openrisc_timer = { + .name = "openrisc_timer", + .rating = 200, + .read = openrisc_timer_read, + .mask = CLOCKSOURCE_MASK(32), + .flags = CLOCK_SOURCE_IS_CONTINUOUS, +}; + +static int __init openrisc_timer_init(void) +{ + struct cpuinfo_or1k *cpuinfo = &cpuinfo_or1k[smp_processor_id()]; + + if (clocksource_register_hz(&openrisc_timer, cpuinfo->clock_frequency)) + panic("failed to register clocksource"); + + /* Enable the incrementer: 'continuous' mode with interrupt disabled */ + mtspr(SPR_TTMR, SPR_TTMR_CR); + + return 0; +} + +void __init time_init(void) +{ + u32 upr; + + upr = mfspr(SPR_UPR); + if (!(upr & SPR_UPR_TTP)) + panic("Linux not supported on devices without tick timer"); + + openrisc_timer_init(); + openrisc_clockevent_init(); + + of_clk_init(NULL); + timer_probe(); +} -- cgit v1.2.3