linux/drivers/clocksource/mips-gic-timer.c

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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved.
*/
#define pr_fmt(fmt) "mips-gic-timer: " fmt
#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/cpu.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/notifier.h>
#include <linux/of_irq.h>
#include <linux/percpu.h>
#include <linux/smp.h>
#include <linux/time.h>
#include <asm/mips-cps.h>
static DEFINE_PER_CPU(struct clock_event_device, gic_clockevent_device);
static int gic_timer_irq;
static unsigned int gic_frequency;
static u64 notrace gic_read_count(void)
{
unsigned int hi, hi2, lo;
if (mips_cm_is64)
return read_gic_counter();
do {
hi = read_gic_counter_32h();
lo = read_gic_counter_32l();
hi2 = read_gic_counter_32h();
} while (hi2 != hi);
return (((u64) hi) << 32) + lo;
}
static int gic_next_event(unsigned long delta, struct clock_event_device *evt)
{
int cpu = cpumask_first(evt->cpumask);
u64 cnt;
int res;
cnt = gic_read_count();
cnt += (u64)delta;
if (cpu == raw_smp_processor_id()) {
write_gic_vl_compare(cnt);
} else {
write_gic_vl_other(mips_cm_vp_id(cpu));
write_gic_vo_compare(cnt);
}
res = ((int)(gic_read_count() - cnt) >= 0) ? -ETIME : 0;
return res;
}
static irqreturn_t gic_compare_interrupt(int irq, void *dev_id)
{
struct clock_event_device *cd = dev_id;
write_gic_vl_compare(read_gic_vl_compare());
cd->event_handler(cd);
return IRQ_HANDLED;
}
static struct irqaction gic_compare_irqaction = {
.handler = gic_compare_interrupt,
.percpu_dev_id = &gic_clockevent_device,
.flags = IRQF_PERCPU | IRQF_TIMER,
.name = "timer",
};
static void gic_clockevent_cpu_init(unsigned int cpu,
struct clock_event_device *cd)
{
cd->name = "MIPS GIC";
cd->features = CLOCK_EVT_FEAT_ONESHOT |
CLOCK_EVT_FEAT_C3STOP;
cd->rating = 350;
cd->irq = gic_timer_irq;
cd->cpumask = cpumask_of(cpu);
cd->set_next_event = gic_next_event;
clockevents_config_and_register(cd, gic_frequency, 0x300, 0x7fffffff);
enable_percpu_irq(gic_timer_irq, IRQ_TYPE_NONE);
}
static void gic_clockevent_cpu_exit(struct clock_event_device *cd)
{
disable_percpu_irq(gic_timer_irq);
}
static void gic_update_frequency(void *data)
{
unsigned long rate = (unsigned long)data;
clockevents_update_freq(this_cpu_ptr(&gic_clockevent_device), rate);
}
static int gic_starting_cpu(unsigned int cpu)
{
gic_clockevent_cpu_init(cpu, this_cpu_ptr(&gic_clockevent_device));
return 0;
}
static int gic_clk_notifier(struct notifier_block *nb, unsigned long action,
void *data)
{
struct clk_notifier_data *cnd = data;
if (action == POST_RATE_CHANGE)
on_each_cpu(gic_update_frequency, (void *)cnd->new_rate, 1);
return NOTIFY_OK;
}
static int gic_dying_cpu(unsigned int cpu)
{
gic_clockevent_cpu_exit(this_cpu_ptr(&gic_clockevent_device));
return 0;
}
static struct notifier_block gic_clk_nb = {
.notifier_call = gic_clk_notifier,
};
static int gic_clockevent_init(void)
{
int ret;
if (!gic_frequency)
return -ENXIO;
ret = setup_percpu_irq(gic_timer_irq, &gic_compare_irqaction);
if (ret < 0) {
pr_err("IRQ %d setup failed (%d)\n", gic_timer_irq, ret);
return ret;
}
cpuhp_setup_state(CPUHP_AP_MIPS_GIC_TIMER_STARTING,
"clockevents/mips/gic/timer:starting",
gic_starting_cpu, gic_dying_cpu);
return 0;
}
static u64 gic_hpt_read(struct clocksource *cs)
{
return gic_read_count();
}
static struct clocksource gic_clocksource = {
MIPS: VDSO: Add implementations of gettimeofday() and clock_gettime() Add user-mode implementations of gettimeofday() and clock_gettime() to the VDSO. This is currently usable with 2 clocksources: the CP0 count register, which is accessible to user-mode via RDHWR on R2 and later cores, or the MIPS Global Interrupt Controller (GIC) timer, which provides a "user-mode visible" section containing a mirror of its counter registers. This section must be mapped into user memory, which is done below the VDSO data page. When a supported clocksource is not in use, the VDSO functions will return -ENOSYS, which causes libc to fall back on the standard syscall path. When support for neither of these clocksources is compiled into the kernel at all, the VDSO still provides clock_gettime(), as the coarse realtime/monotonic clocks can still be implemented. However, gettimeofday() is not provided in this case as nothing can be done without a suitable clocksource. This causes the symbol lookup to fail in libc and it will then always use the standard syscall path. This patch includes a workaround for a bug in QEMU which results in RDHWR on the CP0 count register always returning a constant (incorrect) value. A fix for this has been submitted, and the workaround can be removed after the fix has been in stable releases for a reasonable amount of time. A simple performance test which calls gettimeofday() 1000 times in a loop and calculates the average execution time gives the following results on a Malta + I6400 (running at 20MHz): - Syscall: ~31000 ns - VDSO (GIC): ~15000 ns - VDSO (CP0): ~9500 ns [markos.chandras@imgtec.com: - Minor code re-arrangements in order for mappings to be made in the order they appear to the process' address space. - Move do_{monotonic, realtime} outside of the MIPS_CLOCK_VSYSCALL ifdef - Use gic_get_usm_range so we can do the GIC mapping in the arch/mips/kernel/vdso instead of the GIC irqchip driver] Signed-off-by: Alex Smith <alex.smith@imgtec.com> Signed-off-by: Markos Chandras <markos.chandras@imgtec.com> Cc: linux-kernel@vger.kernel.org Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/11338/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2015-10-21 10:57:44 +02:00
.name = "GIC",
.read = gic_hpt_read,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
.archdata = { .vdso_clock_mode = VDSO_CLOCK_GIC },
};
static int __init __gic_clocksource_init(void)
{
unsigned int count_width;
int ret;
/* Set clocksource mask. */
count_width = read_gic_config() & GIC_CONFIG_COUNTBITS;
count_width >>= __ffs(GIC_CONFIG_COUNTBITS);
count_width *= 4;
count_width += 32;
gic_clocksource.mask = CLOCKSOURCE_MASK(count_width);
/* Calculate a somewhat reasonable rating value. */
gic_clocksource.rating = 200 + gic_frequency / 10000000;
ret = clocksource_register_hz(&gic_clocksource, gic_frequency);
if (ret < 0)
pr_warn("Unable to register clocksource\n");
return ret;
}
clocksource/drivers/mips-gic-timer: Make gic_clocksource_of_init() return int In commit: d8152bf85d2c0 ("clocksource/drivers/mips-gic-timer: Convert init function to return error") several return values were added to a void function resulting in the following warnings: clocksource/mips-gic-timer.c: In function 'gic_clocksource_of_init': clocksource/mips-gic-timer.c:175:3: warning: 'return' with a value, in function returning void [enabled by default] clocksource/mips-gic-timer.c:183:4: warning: 'return' with a value, in function returning void [enabled by default] clocksource/mips-gic-timer.c:190:3: warning: 'return' with a value, in function returning void [enabled by default] clocksource/mips-gic-timer.c:195:3: warning: 'return' with a value, in function returning void [enabled by default] clocksource/mips-gic-timer.c:200:3: warning: 'return' with a value, in function returning void [enabled by default] clocksource/mips-gic-timer.c:211:2: warning: 'return' with a value, in function returning void [enabled by default] clocksource/mips-gic-timer.c: At top level: clocksource/mips-gic-timer.c:213:1: warning: comparison of distinct pointer types lacks a cast [enabled by default] clocksource/mips-gic-timer.c: In function 'gic_clocksource_of_init': clocksource/mips-gic-timer.c:183:18: warning: ignoring return value of 'PTR_ERR', declared with attribute warn_unused_result [-Wunused-result] Given that the addition of the return values was intentional, it seems that the conversion of the containing function from void to int was simply overlooked. Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: linux-mips@linux-mips.org Fixes: d8152bf85d2c ("clocksource/drivers/mips-gic-timer: Convert init function to return error") Link: http://lkml.kernel.org/r/1471429296-9053-3-git-send-email-daniel.lezcano@linaro.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
2016-08-17 12:21:35 +02:00
static int __init gic_clocksource_of_init(struct device_node *node)
{
struct clk *clk;
int ret;
if (!mips_gic_present() || !node->parent ||
!of_device_is_compatible(node->parent, "mti,gic")) {
pr_warn("No DT definition\n");
return -ENXIO;
}
clk = of_clk_get(node, 0);
if (!IS_ERR(clk)) {
ret = clk_prepare_enable(clk);
if (ret < 0) {
pr_err("Failed to enable clock\n");
clk_put(clk);
return ret;
}
gic_frequency = clk_get_rate(clk);
} else if (of_property_read_u32(node, "clock-frequency",
&gic_frequency)) {
pr_err("Frequency not specified\n");
return -EINVAL;
}
gic_timer_irq = irq_of_parse_and_map(node, 0);
if (!gic_timer_irq) {
pr_err("IRQ not specified\n");
return -EINVAL;
}
ret = __gic_clocksource_init();
if (ret)
return ret;
ret = gic_clockevent_init();
if (!ret && !IS_ERR(clk)) {
if (clk_notifier_register(clk, &gic_clk_nb) < 0)
pr_warn("Unable to register clock notifier\n");
}
/* And finally start the counter */
clear_gic_config(GIC_CONFIG_COUNTSTOP);
return 0;
}
TIMER_OF_DECLARE(mips_gic_timer, "mti,gic-timer",
gic_clocksource_of_init);