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Subject[PATCH] clocksource: Ingenic: Add high resolution timer support for SMP.
Date
From: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>

Enable clock event handling on per CPU core basis.
Make sure that interrupts raised on the first core execute
event handlers on the correct CPU core.

Tested-by: H. Nikolaus Schaller <hns@goldelico.com>
Tested-by: Paul Boddie <paul@boddie.org.uk>
Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---

Zhou:

I took the liberty to clean your patch so that it doesn't create a
struct ingenic_tcu per CPU timer.

Tested, and fully working on the JZ4770 with CONFIG_SMP disabled, and
also with CONFIG_SMP enabled (even though JZ4770 has only one CPU) with
a fixed smp.c and USB disabled (otherwise it crashes at boot).

Cheers,
-Paul

drivers/clocksource/ingenic-timer.c | 180 +++++++++++++++++++---------
1 file changed, 123 insertions(+), 57 deletions(-)

diff --git a/drivers/clocksource/ingenic-timer.c b/drivers/clocksource/ingenic-timer.c
index 496333650de2..a068e4620c44 100644
--- a/drivers/clocksource/ingenic-timer.c
+++ b/drivers/clocksource/ingenic-timer.c
@@ -2,6 +2,7 @@
/*
* JZ47xx SoCs TCU IRQ driver
* Copyright (C) 2019 Paul Cercueil <paul@crapouillou.net>
+ * Copyright (C) 2020 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
*/

#include <linux/bitops.h>
@@ -15,24 +16,35 @@
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h>
+#include <linux/overflow.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/sched_clock.h>

#include <dt-bindings/clock/ingenic,tcu.h>

+static DEFINE_PER_CPU(call_single_data_t, ingenic_cevt_csd);
+
struct ingenic_soc_info {
unsigned int num_channels;
};

+struct ingenic_tcu_timer {
+ unsigned int cpu;
+ unsigned int channel;
+ struct clock_event_device cevt;
+ struct clk *clk;
+ char name[8];
+};
+
struct ingenic_tcu {
struct regmap *map;
- struct clk *timer_clk, *cs_clk;
- unsigned int timer_channel, cs_channel;
- struct clock_event_device cevt;
+ struct device_node *np;
+ struct clk *cs_clk;
+ unsigned int cs_channel;
struct clocksource cs;
- char name[4];
unsigned long pwm_channels_mask;
+ struct ingenic_tcu_timer timers[];
};

static struct ingenic_tcu *ingenic_tcu;
@@ -52,16 +64,24 @@ static u64 notrace ingenic_tcu_timer_cs_read(struct clocksource *cs)
return ingenic_tcu_timer_read();
}

-static inline struct ingenic_tcu *to_ingenic_tcu(struct clock_event_device *evt)
+static inline struct ingenic_tcu *
+to_ingenic_tcu(struct ingenic_tcu_timer *timer)
+{
+ return container_of(timer, struct ingenic_tcu, timers[timer->cpu]);
+}
+
+static inline struct ingenic_tcu_timer *
+to_ingenic_tcu_timer(struct clock_event_device *evt)
{
- return container_of(evt, struct ingenic_tcu, cevt);
+ return container_of(evt, struct ingenic_tcu_timer, cevt);
}

static int ingenic_tcu_cevt_set_state_shutdown(struct clock_event_device *evt)
{
- struct ingenic_tcu *tcu = to_ingenic_tcu(evt);
+ struct ingenic_tcu_timer *timer = to_ingenic_tcu_timer(evt);
+ struct ingenic_tcu *tcu = to_ingenic_tcu(timer);

- regmap_write(tcu->map, TCU_REG_TECR, BIT(tcu->timer_channel));
+ regmap_write(tcu->map, TCU_REG_TECR, BIT(timer->channel));

return 0;
}
@@ -69,27 +89,40 @@ static int ingenic_tcu_cevt_set_state_shutdown(struct clock_event_device *evt)
static int ingenic_tcu_cevt_set_next(unsigned long next,
struct clock_event_device *evt)
{
- struct ingenic_tcu *tcu = to_ingenic_tcu(evt);
+ struct ingenic_tcu_timer *timer = to_ingenic_tcu_timer(evt);
+ struct ingenic_tcu *tcu = to_ingenic_tcu(timer);

if (next > 0xffff)
return -EINVAL;

- regmap_write(tcu->map, TCU_REG_TDFRc(tcu->timer_channel), next);
- regmap_write(tcu->map, TCU_REG_TCNTc(tcu->timer_channel), 0);
- regmap_write(tcu->map, TCU_REG_TESR, BIT(tcu->timer_channel));
+ regmap_write(tcu->map, TCU_REG_TDFRc(timer->channel), next);
+ regmap_write(tcu->map, TCU_REG_TCNTc(timer->channel), 0);
+ regmap_write(tcu->map, TCU_REG_TESR, BIT(timer->channel));

return 0;
}

+static void ingenic_per_cpu_event_handler(void *info)
+{
+ struct clock_event_device *cevt = (struct clock_event_device *) info;
+
+ cevt->event_handler(cevt);
+}
+
static irqreturn_t ingenic_tcu_cevt_cb(int irq, void *dev_id)
{
- struct clock_event_device *evt = dev_id;
- struct ingenic_tcu *tcu = to_ingenic_tcu(evt);
+ struct ingenic_tcu_timer *timer = dev_id;
+ struct ingenic_tcu *tcu = to_ingenic_tcu(timer);
+ call_single_data_t *csd;

- regmap_write(tcu->map, TCU_REG_TECR, BIT(tcu->timer_channel));
+ regmap_write(tcu->map, TCU_REG_TECR, BIT(timer->channel));

- if (evt->event_handler)
- evt->event_handler(evt);
+ if (timer->cevt.event_handler) {
+ csd = &per_cpu(ingenic_cevt_csd, timer->cpu);
+ csd->info = (void *) &timer->cevt;
+ csd->func = ingenic_per_cpu_event_handler;
+ smp_call_function_single_async(timer->cpu, csd);
+ }

return IRQ_HANDLED;
}
@@ -105,64 +138,66 @@ static struct clk * __init ingenic_tcu_get_clock(struct device_node *np, int id)
return of_clk_get_from_provider(&args);
}

-static int __init ingenic_tcu_timer_init(struct device_node *np,
- struct ingenic_tcu *tcu)
+static int ingenic_tcu_setup_cevt(unsigned int cpu)
{
- unsigned int timer_virq, channel = tcu->timer_channel;
+ struct ingenic_tcu *tcu = ingenic_tcu;
+ struct ingenic_tcu_timer *timer = &tcu->timers[cpu];
+ unsigned int timer_virq;
struct irq_domain *domain;
unsigned long rate;
int err;

- tcu->timer_clk = ingenic_tcu_get_clock(np, channel);
- if (IS_ERR(tcu->timer_clk))
- return PTR_ERR(tcu->timer_clk);
+ timer->clk = ingenic_tcu_get_clock(tcu->np, timer->channel);
+ if (IS_ERR(timer->clk))
+ return PTR_ERR(timer->clk);

- err = clk_prepare_enable(tcu->timer_clk);
+ err = clk_prepare_enable(timer->clk);
if (err)
goto err_clk_put;

- rate = clk_get_rate(tcu->timer_clk);
+ rate = clk_get_rate(timer->clk);
if (!rate) {
err = -EINVAL;
goto err_clk_disable;
}

- domain = irq_find_host(np);
+ domain = irq_find_host(tcu->np);
if (!domain) {
err = -ENODEV;
goto err_clk_disable;
}

- timer_virq = irq_create_mapping(domain, channel);
+ timer_virq = irq_create_mapping(domain, timer->channel);
if (!timer_virq) {
err = -EINVAL;
goto err_clk_disable;
}

- snprintf(tcu->name, sizeof(tcu->name), "TCU");
+ snprintf(timer->name, sizeof(timer->name), "TCU%u", timer->channel);

err = request_irq(timer_virq, ingenic_tcu_cevt_cb, IRQF_TIMER,
- tcu->name, &tcu->cevt);
+ timer->name, timer);
if (err)
goto err_irq_dispose_mapping;

- tcu->cevt.cpumask = cpumask_of(smp_processor_id());
- tcu->cevt.features = CLOCK_EVT_FEAT_ONESHOT;
- tcu->cevt.name = tcu->name;
- tcu->cevt.rating = 200;
- tcu->cevt.set_state_shutdown = ingenic_tcu_cevt_set_state_shutdown;
- tcu->cevt.set_next_event = ingenic_tcu_cevt_set_next;
+ timer->cpu = smp_processor_id();
+ timer->cevt.cpumask = cpumask_of(smp_processor_id());
+ timer->cevt.features = CLOCK_EVT_FEAT_ONESHOT;
+ timer->cevt.name = timer->name;
+ timer->cevt.rating = 200;
+ timer->cevt.set_state_shutdown = ingenic_tcu_cevt_set_state_shutdown;
+ timer->cevt.set_next_event = ingenic_tcu_cevt_set_next;

- clockevents_config_and_register(&tcu->cevt, rate, 10, 0xffff);
+ clockevents_config_and_register(&timer->cevt, rate, 10, 0xffff);

return 0;

err_irq_dispose_mapping:
irq_dispose_mapping(timer_virq);
err_clk_disable:
- clk_disable_unprepare(tcu->timer_clk);
+ clk_disable_unprepare(timer->clk);
err_clk_put:
- clk_put(tcu->timer_clk);
+ clk_put(timer->clk);
return err;
}

@@ -238,10 +273,12 @@ static int __init ingenic_tcu_init(struct device_node *np)
{
const struct of_device_id *id = of_match_node(ingenic_tcu_of_match, np);
const struct ingenic_soc_info *soc_info = id->data;
+ struct ingenic_tcu_timer *timer;
struct ingenic_tcu *tcu;
struct regmap *map;
+ unsigned int cpu;
+ int ret, last_bit = -1;
long rate;
- int ret;

of_node_clear_flag(np, OF_POPULATED);

@@ -249,17 +286,23 @@ static int __init ingenic_tcu_init(struct device_node *np)
if (IS_ERR(map))
return PTR_ERR(map);

- tcu = kzalloc(sizeof(*tcu), GFP_KERNEL);
+ tcu = kzalloc(struct_size(tcu, timers, num_possible_cpus()),
+ GFP_KERNEL);
if (!tcu)
return -ENOMEM;

- /* Enable all TCU channels for PWM use by default except channels 0/1 */
- tcu->pwm_channels_mask = GENMASK(soc_info->num_channels - 1, 2);
+ /*
+ * Enable all TCU channels for PWM use by default except channels 0/1,
+ * and channel 2 if target CPU is JZ4780 and SMP is selected.
+ */
+ tcu->pwm_channels_mask = GENMASK(soc_info->num_channels - 1,
+ num_possible_cpus() + 1);
of_property_read_u32(np, "ingenic,pwm-channels-mask",
(u32 *)&tcu->pwm_channels_mask);

- /* Verify that we have at least two free channels */
- if (hweight8(tcu->pwm_channels_mask) > soc_info->num_channels - 2) {
+ /* Verify that we have at least num_possible_cpus() + 1 free channels */
+ if (hweight8(tcu->pwm_channels_mask) >
+ soc_info->num_channels - num_possible_cpus() + 1) {
pr_crit("%s: Invalid PWM channel mask: 0x%02lx\n", __func__,
tcu->pwm_channels_mask);
ret = -EINVAL;
@@ -267,13 +310,22 @@ static int __init ingenic_tcu_init(struct device_node *np)
}

tcu->map = map;
+ tcu->np = np;
ingenic_tcu = tcu;

- tcu->timer_channel = find_first_zero_bit(&tcu->pwm_channels_mask,
- soc_info->num_channels);
+ for (cpu = 0; cpu < num_possible_cpus(); cpu++) {
+ timer = &tcu->timers[cpu];
+
+ timer->cpu = cpu;
+ timer->channel = find_next_zero_bit(&tcu->pwm_channels_mask,
+ soc_info->num_channels,
+ last_bit + 1);
+ last_bit = timer->channel;
+ }
+
tcu->cs_channel = find_next_zero_bit(&tcu->pwm_channels_mask,
soc_info->num_channels,
- tcu->timer_channel + 1);
+ last_bit + 1);

ret = ingenic_tcu_clocksource_init(np, tcu);
if (ret) {
@@ -281,9 +333,13 @@ static int __init ingenic_tcu_init(struct device_node *np)
goto err_free_ingenic_tcu;
}

- ret = ingenic_tcu_timer_init(np, tcu);
- if (ret)
+ /* Setup clock events on each CPU core */
+ ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "Ingenic XBurst: online",
+ ingenic_tcu_setup_cevt, NULL);
+ if (ret < 0) {
+ pr_crit("%s: Unable to start CPU timers: %d\n", __func__, ret);
goto err_tcu_clocksource_cleanup;
+ }

/* Register the sched_clock at the end as there's no way to undo it */
rate = clk_get_rate(tcu->cs_clk);
@@ -315,28 +371,38 @@ static int __init ingenic_tcu_probe(struct platform_device *pdev)
static int __maybe_unused ingenic_tcu_suspend(struct device *dev)
{
struct ingenic_tcu *tcu = dev_get_drvdata(dev);
+ unsigned int cpu;

clk_disable(tcu->cs_clk);
- clk_disable(tcu->timer_clk);
+
+ for (cpu = 0; cpu < num_online_cpus(); cpu++)
+ clk_disable(tcu->timers[cpu].clk);
+
return 0;
}

static int __maybe_unused ingenic_tcu_resume(struct device *dev)
{
struct ingenic_tcu *tcu = dev_get_drvdata(dev);
+ unsigned int cpu;
int ret;

- ret = clk_enable(tcu->timer_clk);
- if (ret)
- return ret;
+ for (cpu = 0; cpu < num_online_cpus(); cpu++) {
+ ret = clk_enable(tcu->timers[cpu].clk);
+ if (ret)
+ goto err_timer_clk_disable;
+ }

ret = clk_enable(tcu->cs_clk);
- if (ret) {
- clk_disable(tcu->timer_clk);
- return ret;
- }
+ if (ret)
+ goto err_timer_clk_disable;

return 0;
+
+err_timer_clk_disable:
+ for (; cpu > 0; cpu--)
+ clk_disable(tcu->timers[cpu - 1].clk);
+ return ret;
}

static const struct dev_pm_ops __maybe_unused ingenic_tcu_pm_ops = {
--
2.26.2
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