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Date: Thu, 20 Feb 2020 15:33:04 -0300
From: Paul Cercueil <paul@...pouillou.net>
To: 周琰杰 "(Zhou Yanjie)"
<zhouyanjie@...yeetech.com>
Cc: linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
tglx@...utronix.de, ralf@...ux-mips.org, paulburton@...nel.org,
jiaxun.yang@...goat.com, chenhc@...ote.com, sboyd@...nel.org,
mturquette@...libre.com, mark.rutland@....com, robh+dt@...nel.org,
daniel.lezcano@...aro.org, geert+renesas@...der.be,
krzk@...nel.org, ebiederm@...ssion.com, miquel.raynal@...tlin.com,
keescook@...omium.org, sernia.zhou@...mail.com,
zhenwenjin@...il.com, dongsheng.qiu@...enic.com
Subject: Re: [PATCH v6 4/7] clocksource: Ingenic: Add high resolution timer
support for SMP.
Hi Zhou,
Le ven., févr. 21, 2020 at 00:24, 周琰杰 (Zhou Yanjie)
<zhouyanjie@...yeetech.com> a écrit :
> 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@...delico.com>
> Tested-by: Paul Boddie <paul@...die.org.uk>
> Signed-off-by: 周琰杰 (Zhou Yanjie) <zhouyanjie@...yeetech.com>
> ---
>
> 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.
>
> drivers/clocksource/ingenic-timer.c | 113
> +++++++++++++++++++++++++++++-------
> 1 file changed, 91 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/clocksource/ingenic-timer.c
> b/drivers/clocksource/ingenic-timer.c
> index 4bbdb3d..e396326 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@...pouillou.net>
> + * Copyright (C) 2020 周琰杰 (Zhou Yanjie)
> <zhouyanjie@...yeetech.com>
> */
>
> #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)
> {
> @@ -239,6 +291,7 @@ 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;
>
> @@ -252,13 +305,18 @@ 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) {
NR_CPUS can be up to 256. You want to use num_online_cpus() here, I
believe.
> pr_crit("%s: Invalid PWM channel mask: 0x%02lx\n", __func__,
> tcu->pwm_channels_mask);
> ret = -EINVAL;
> @@ -266,13 +324,27 @@ 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);
> - tcu->cs_channel = find_next_zero_bit(&tcu->pwm_channels_mask,
> - soc_info->num_channels,
> - tcu->timer_channel + 1);
> +
> + if (NR_CPUS > 1) {
> + 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_local[cpu-1] + 1);
> + } else {
> + tcu->cs_channel = find_next_zero_bit(&tcu->pwm_channels_mask,
> + soc_info->num_channels,
> + tcu->timer_local[cpu] + 1);
> + }
I believe you can factorize the code a bit here - don't check for
NR_CPUS > 1, and have a for (cpu = 0; cpu < num_online_cpus(); cpu++)
loop. You could use a temporary variable to store the 'next bit' value.
-Paul
>
> ret = ingenic_tcu_clocksource_init(np, tcu);
> if (ret) {
> @@ -280,9 +352,10 @@ 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);
> @@ -290,10 +363,6 @@ 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
>
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