[PATCH v7 3/6] clocksource: Ingenic: Add high resolution timer support for SMP.

From: åçæ (Zhou Yanjie)
Date: Wed May 13 2020 - 14:47:11 EST

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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@xxxxxxxxxxxxx>
Tested-by: Paul Boddie <paul@xxxxxxxxxxxxx>
Signed-off-by: åçæ (Zhou Yanjie) <zhouyanjie@xxxxxxxxxxxxxx>
---

Notes:
v1->v2:
1.Adjust function naming to make it more reasonable.
2.Replace function smp_call_function_single() with
smp_call_function_single_async() in order to resolve
the warning below:

[ 0.350942] smp: Brought up 1 node, 2 CPUs
[ 0.365497] ------------[ cut here ]------------
[ 0.365522] WARNING: CPU: 0 PID: 1 at kernel/smp.c:300 smp_call_function_single+0x110/0x200
[ 0.365533] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.5.0-rc1+ #5
[ 0.365537] Stack : 00000000 59c73bcd 00000037 80074e80 80000000 80670000 805a0000 80620590
[ 0.365557] 8065ce38 8fc0dc8c 806d0000 00000000 80670000 00000001 8fc0dc20 59c73bcd
[ 0.365574] 00000000 00000000 806f0000 80670000 00000000 806dab00 00000000 2d302e35
[ 0.365591] 203a6d6d 806e0000 806e0000 70617773 80670000 00000000 00000000 00000009
[ 0.365610] 00000000 8fc94e20 8fc0de30 80690000 00000018 803592dc 00000000 806d0000
[ 0.365627] ...
[ 0.365634] Call Trace:
[ 0.365647] [<8001b9a0>] show_stack+0x6c/0x12c
[ 0.365663] [<804aed20>] dump_stack+0x98/0xc8
[ 0.365673] [<8003044c>] __warn+0xc4/0xe8
[ 0.365682] [<800304f4>] warn_slowpath_fmt+0x84/0xb8
[ 0.365690] [<800a886c>] smp_call_function_single+0x110/0x200
[ 0.365703] ---[ end trace 5785856ca39c79d5 ]---
[ 0.365557] 8065ce38 8fc0dc8c 806d0000 00000000 80670000 00000001 8fc0dc20 59c73bcd
[ 0.365574] 00000000 00000000 806f0000 80670000 00000000 806dab00 00000000 2d302e35
[ 0.365591] 203a6d6d 806e0000 806e0000 70617773 80670000 00000000 00000000 00000009
[ 0.365610] 00000000 8fc94e20 8fc0de30 80690000 00000018 803592dc 00000000 806d0000
[ 0.365627] ...
[ 0.365634] Call Trace:
[ 0.365647] [<8001b9a0>] show_stack+0x6c/0x12c
[ 0.365663] [<804aed20>] dump_stack+0x98/0xc8
[ 0.365673] [<8003044c>] __warn+0xc4/0xe8
[ 0.365682] [<800304f4>] warn_slowpath_fmt+0x84/0xb8
[ 0.365690] [<800a886c>] smp_call_function_single+0x110/0x200
[ 0.365703] ---[ end trace 5785856ca39c79d5 ]---

v2->v3:
No Change.

v3->v4:
Rebase on top of kernel 5.6-rc1.

v4->v5:
Move the check for (evt->event_handler) from "ingenic_per_cpu_event_handler"
to "ingenic_tcu_cevt_cb".

v5->v6:
No change.

v6->v7:
Remove unnecessary check for "NR_CPUS > 1".

drivers/clocksource/ingenic-timer.c | 103 ++++++++++++++++++++++++++++--------
1 file changed, 82 insertions(+), 21 deletions(-)

diff --git a/drivers/clocksource/ingenic-timer.c b/drivers/clocksource/ingenic-timer.c
index 4963336..9aae939 100644
--- a/drivers/clocksource/ingenic-timer.c
+++ b/drivers/clocksource/ingenic-timer.c
@@ -1,7 +1,8 @@
// SPDX-License-Identifier: GPL-2.0
/*
- * JZ47xx SoCs TCU IRQ driver
+ * XBurst SoCs TCU IRQ driver
* Copyright (C) 2019 Paul Cercueil <paul@xxxxxxxxxxxxxxx>
+ * Copyright (C) 2020 åçæ (Zhou Yanjie) <zhouyanjie@xxxxxxxxxxxxxx>
*/

#include <linux/bitops.h>
@@ -21,18 +22,23 @@

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

static struct ingenic_tcu *ingenic_tcu;
@@ -81,6 +87,24 @@ static int ingenic_tcu_cevt_set_next(unsigned long next,
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 void ingenic_tcu_per_cpu_cb(struct clock_event_device *evt)
+{
+ struct ingenic_tcu *tcu = to_ingenic_tcu(evt);
+ call_single_data_t *csd;
+
+ csd = &per_cpu(ingenic_cevt_csd, tcu->cpu);
+ csd->info = (void *) evt;
+ csd->func = ingenic_per_cpu_event_handler;
+ smp_call_function_single_async(tcu->cpu, csd);
+}
+
static irqreturn_t ingenic_tcu_cevt_cb(int irq, void *dev_id)
{
struct clock_event_device *evt = dev_id;
@@ -89,7 +113,7 @@ static irqreturn_t ingenic_tcu_cevt_cb(int irq, void *dev_id)
regmap_write(tcu->map, TCU_REG_TECR, BIT(tcu->timer_channel));

if (evt->event_handler)
- evt->event_handler(evt);
+ ingenic_tcu_per_cpu_cb(evt);

return IRQ_HANDLED;
}
@@ -105,14 +129,21 @@ 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_per_cpu_cevt(struct device_node *np,
+ unsigned int channel)
{
- unsigned int timer_virq, channel = tcu->timer_channel;
+ unsigned int timer_virq;
struct irq_domain *domain;
+ struct ingenic_tcu *tcu;
unsigned long rate;
int err;

+ tcu = kzalloc(sizeof(*tcu), GFP_KERNEL);
+ if (!tcu)
+ return -ENOMEM;
+
+ tcu->map = ingenic_tcu->map;
+
tcu->timer_clk = ingenic_tcu_get_clock(np, channel);
if (IS_ERR(tcu->timer_clk))
return PTR_ERR(tcu->timer_clk);
@@ -139,13 +170,15 @@ static int __init ingenic_tcu_timer_init(struct device_node *np,
goto err_clk_disable;
}

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

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

+ tcu->cpu = smp_processor_id();
+ tcu->timer_channel = channel;
tcu->cevt.cpumask = cpumask_of(smp_processor_id());
tcu->cevt.features = CLOCK_EVT_FEAT_ONESHOT;
tcu->cevt.name = tcu->name;
@@ -166,6 +199,25 @@ static int __init ingenic_tcu_timer_init(struct device_node *np,
return err;
}

+static int ingenic_tcu_setup_cevt(unsigned int cpu)
+{
+ int ret;
+
+ ret = ingenic_tcu_setup_per_cpu_cevt(ingenic_tcu->np,
+ ingenic_tcu->timer_local[cpu]);
+ if (ret)
+ goto err_tcu_clocksource_cleanup;
+
+ return 0;
+
+err_tcu_clocksource_cleanup:
+ clocksource_unregister(&ingenic_tcu->cs);
+ clk_disable_unprepare(ingenic_tcu->cs_clk);
+ clk_put(ingenic_tcu->cs_clk);
+ kfree(ingenic_tcu);
+ return ret;
+}
+
static int __init ingenic_tcu_clocksource_init(struct device_node *np,
struct ingenic_tcu *tcu)
{
@@ -240,6 +292,7 @@ static int __init ingenic_tcu_init(struct device_node *np)
const struct ingenic_soc_info *soc_info = id->data;
struct ingenic_tcu *tcu;
struct regmap *map;
+ unsigned cpu = 0;
long rate;
int ret;

@@ -253,13 +306,18 @@ static int __init ingenic_tcu_init(struct device_node *np)
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,
+ NR_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 NR_CPUS + 1 free channels */
+ if (hweight8(tcu->pwm_channels_mask) >
+ soc_info->num_channels - NR_CPUS + 1) {
pr_crit("%s: Invalid PWM channel mask: 0x%02lx\n", __func__,
tcu->pwm_channels_mask);
ret = -EINVAL;
@@ -267,13 +325,19 @@ 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,
+ tcu->timer_local[cpu] = find_first_zero_bit(&tcu->pwm_channels_mask,
soc_info->num_channels);
+
+ for (cpu = 1; cpu < NR_CPUS; cpu++)
+ tcu->timer_local[cpu] = find_next_zero_bit(
+ &tcu->pwm_channels_mask, soc_info->num_channels,
+ tcu->timer_local[cpu - 1] + 1);
+
tcu->cs_channel = find_next_zero_bit(&tcu->pwm_channels_mask,
- soc_info->num_channels,
- tcu->timer_channel + 1);
+ soc_info->num_channels, tcu->timer_local[cpu - 1] + 1);

ret = ingenic_tcu_clocksource_init(np, tcu);
if (ret) {
@@ -281,9 +345,10 @@ static int __init ingenic_tcu_init(struct device_node *np)
goto err_free_ingenic_tcu;
}

- ret = ingenic_tcu_timer_init(np, tcu);
- if (ret)
- goto err_tcu_clocksource_cleanup;
+ /* Setup clock events on each CPU core */
+ ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "Ingenic XBurst: online",
+ ingenic_tcu_setup_cevt, NULL);
+ WARN_ON(ret < 0);

/* Register the sched_clock at the end as there's no way to undo it */
rate = clk_get_rate(tcu->cs_clk);
@@ -291,10 +356,6 @@ static int __init ingenic_tcu_init(struct device_node *np)

return 0;

-err_tcu_clocksource_cleanup:
- clocksource_unregister(&tcu->cs);
- clk_disable_unprepare(tcu->cs_clk);
- clk_put(tcu->cs_clk);
err_free_ingenic_tcu:
kfree(tcu);
return ret;
--
2.7.4

Next message: åçæ (Zhou Yanjie): "[PATCH v7 5/6] MIPS: Ingenic: Add 'cpus' node for Ingenic SoCs."
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Next in thread: kbuild test robot: "Re: [PATCH v7 3/6] clocksource: Ingenic: Add high resolution timer support for SMP."
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