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![Paul Gortmaker](/assets/img/avatar_default.png)
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications. For example, the fix in
commit 5e427ec2d0
("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.
After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out. Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.
This removes all the drivers/clocksource and drivers/irqchip uses of
the __cpuinit macros from all C files.
[1] https://lkml.org/lkml/2013/5/20/589
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
200 lines
5.2 KiB
C
200 lines
5.2 KiB
C
/*
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* Copyright (C) 2005-2013 Imagination Technologies Ltd.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*
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*
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* Support for Meta per-thread timers.
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*
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* Meta hardware threads have 2 timers. The background timer (TXTIMER) is used
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* as a free-running time base (hz clocksource), and the interrupt timer
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* (TXTIMERI) is used for the timer interrupt (clock event). Both counters
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* traditionally count at approximately 1MHz.
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*/
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#include <clocksource/metag_generic.h>
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#include <linux/cpu.h>
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/kernel.h>
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#include <linux/param.h>
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#include <linux/time.h>
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#include <linux/init.h>
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#include <linux/proc_fs.h>
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#include <linux/clocksource.h>
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#include <linux/clockchips.h>
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#include <linux/interrupt.h>
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#include <asm/clock.h>
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#include <asm/hwthread.h>
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#include <asm/core_reg.h>
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#include <asm/metag_mem.h>
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#include <asm/tbx.h>
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#define HARDWARE_FREQ 1000000 /* 1MHz */
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#define HARDWARE_DIV 1 /* divide by 1 = 1MHz clock */
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#define HARDWARE_TO_NS_SHIFT 10 /* convert ticks to ns */
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static unsigned int hwtimer_freq = HARDWARE_FREQ;
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static DEFINE_PER_CPU(struct clock_event_device, local_clockevent);
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static DEFINE_PER_CPU(char [11], local_clockevent_name);
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static int metag_timer_set_next_event(unsigned long delta,
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struct clock_event_device *dev)
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{
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__core_reg_set(TXTIMERI, -delta);
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return 0;
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}
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static void metag_timer_set_mode(enum clock_event_mode mode,
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struct clock_event_device *evt)
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{
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switch (mode) {
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case CLOCK_EVT_MODE_ONESHOT:
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case CLOCK_EVT_MODE_RESUME:
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break;
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case CLOCK_EVT_MODE_SHUTDOWN:
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/* We should disable the IRQ here */
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break;
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case CLOCK_EVT_MODE_PERIODIC:
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case CLOCK_EVT_MODE_UNUSED:
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WARN_ON(1);
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break;
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};
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}
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static cycle_t metag_clocksource_read(struct clocksource *cs)
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{
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return __core_reg_get(TXTIMER);
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}
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static struct clocksource clocksource_metag = {
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.name = "META",
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.rating = 200,
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.mask = CLOCKSOURCE_MASK(32),
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.read = metag_clocksource_read,
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.flags = CLOCK_SOURCE_IS_CONTINUOUS,
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};
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static irqreturn_t metag_timer_interrupt(int irq, void *dummy)
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{
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struct clock_event_device *evt = &__get_cpu_var(local_clockevent);
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evt->event_handler(evt);
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return IRQ_HANDLED;
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}
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static struct irqaction metag_timer_irq = {
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.name = "META core timer",
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.handler = metag_timer_interrupt,
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.flags = IRQF_TIMER | IRQF_IRQPOLL | IRQF_PERCPU,
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};
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unsigned long long sched_clock(void)
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{
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unsigned long long ticks = __core_reg_get(TXTIMER);
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return ticks << HARDWARE_TO_NS_SHIFT;
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}
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static void arch_timer_setup(unsigned int cpu)
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{
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unsigned int txdivtime;
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struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);
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char *name = per_cpu(local_clockevent_name, cpu);
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txdivtime = __core_reg_get(TXDIVTIME);
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txdivtime &= ~TXDIVTIME_DIV_BITS;
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txdivtime |= (HARDWARE_DIV & TXDIVTIME_DIV_BITS);
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__core_reg_set(TXDIVTIME, txdivtime);
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sprintf(name, "META %d", cpu);
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clk->name = name;
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clk->features = CLOCK_EVT_FEAT_ONESHOT,
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clk->rating = 200,
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clk->shift = 12,
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clk->irq = tbisig_map(TBID_SIGNUM_TRT),
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clk->set_mode = metag_timer_set_mode,
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clk->set_next_event = metag_timer_set_next_event,
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clk->mult = div_sc(hwtimer_freq, NSEC_PER_SEC, clk->shift);
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clk->max_delta_ns = clockevent_delta2ns(0x7fffffff, clk);
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clk->min_delta_ns = clockevent_delta2ns(0xf, clk);
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clk->cpumask = cpumask_of(cpu);
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clockevents_register_device(clk);
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/*
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* For all non-boot CPUs we need to synchronize our free
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* running clock (TXTIMER) with the boot CPU's clock.
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*
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* While this won't be accurate, it should be close enough.
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*/
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if (cpu) {
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unsigned int thread0 = cpu_2_hwthread_id[0];
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unsigned long val;
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val = core_reg_read(TXUCT_ID, TXTIMER_REGNUM, thread0);
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__core_reg_set(TXTIMER, val);
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}
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}
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static int arch_timer_cpu_notify(struct notifier_block *self,
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unsigned long action, void *hcpu)
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{
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int cpu = (long)hcpu;
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switch (action) {
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case CPU_STARTING:
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case CPU_STARTING_FROZEN:
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arch_timer_setup(cpu);
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break;
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}
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return NOTIFY_OK;
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}
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static struct notifier_block arch_timer_cpu_nb = {
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.notifier_call = arch_timer_cpu_notify,
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};
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int __init metag_generic_timer_init(void)
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{
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/*
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* On Meta 2 SoCs, the actual frequency of the timer is based on the
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* Meta core clock speed divided by an integer, so it is only
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* approximately 1MHz. Calculating the real frequency here drastically
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* reduces clock skew on these SoCs.
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*/
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#ifdef CONFIG_METAG_META21
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hwtimer_freq = get_coreclock() / (metag_in32(EXPAND_TIMER_DIV) + 1);
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#endif
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pr_info("Timer frequency: %u Hz\n", hwtimer_freq);
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clocksource_register_hz(&clocksource_metag, hwtimer_freq);
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setup_irq(tbisig_map(TBID_SIGNUM_TRT), &metag_timer_irq);
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/* Configure timer on boot CPU */
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arch_timer_setup(smp_processor_id());
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/* Hook cpu boot to configure other CPU's timers */
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register_cpu_notifier(&arch_timer_cpu_nb);
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return 0;
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}
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