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Subject: Re: [PATCH v10 1/2] clocksource: loongson2_hpet: add hpet driver
 support
To:     Daniel Lezcano <daniel.lezcano@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Huacai Chen <chenhuacai@kernel.org>,
        WANG Xuerui <kernel@xen0n.name>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        Jianmin Lv <lvjianmin@loongson.cn>,
        Yun Liu <liuyun@loongson.cn>,
        Yang Li <yang.lee@linux.alibaba.com>,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        loongarch@lists.linux.dev
References: <20221103131202.12481-1-zhuyinbo@loongson.cn>
From:   Yinbo Zhu <zhuyinbo@loongson.cn>
Message-ID: <4d194eb7-2de9-38d1-1c87-ee107d973b3c@loongson.cn>
Date:   Wed, 9 Nov 2022 17:48:59 +0800
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Hi maintainer,

I don't find clocksoure/timer tree so I verified it in mainline 6.1-rc3.
if no other issue, please help me merge it to upstream.

In addition, this patch need rely on 
"https://patchwork.kernel.org/project/linux-clk/list/?series=691497"

Thanks,
Yinbo.

?? 2022/11/3 ????9:12, Yinbo Zhu д??:
> HPET (High Precision Event Timer) defines a new set of timers, which
> are used by the operating system to schedule threads, interrupt the
> kernel and interrupt the multimedia timer server. The operating
> system can assign different timers to different applications. By
> configuration, each timer can generate interrupt independently.
> 
> The Loongson-2 HPET module includes a main count and three comparators,
> all of which are 32 bits wide. Among the three comparators, only
> one comparator supports periodic interrupt, all three comparators
> support non periodic interrupts.
> 
> Signed-off-by: Yinbo Zhu <zhuyinbo@loongson.cn>
> ---
> Change in v10:
> 		1. Replace "goto err" with "return -ENOMEM" if of_iomap fail.
>                  2. This patch need rely on clock patch, which patchwork
> 		   link was "https://patchwork.kernel.org/project/linux-clk/list/?series=691497".
> Change in v9:
> 		1. Replace string "register" with "request" in hpet_request_irq.
> 		2. Move the varible "ret" to the begining position in
> 		   loongson2_hpet_init and initialized it.
> 		3. Adjust if judgement in clk_get_rate context, there was less
> 		   less indentation in the normal path.
>                  4. This patch need rely on clock patch, which patchwork
> 		   link was "https://patchwork.kernel.org/project/linux-clk/list/?series=691497".
> Change in v8:
> 		1. Add all history change log information.
> Change in v7:
> 		1. Replace setup_irq with request_irq.
> Change in v6:
> 		1. Move comma to the end of the previous line if that comma at
> 		   the beginning of the line.
> Change in v5:
> 		1. Replace string loongson2 with Loongson-2 in commit message
> 		   and Kconfig file.
> 		2. Replace string LOONGSON2 with LOONGSON-2 in MAINTAINERS.
> 		3. Make include asm headers after all linux headers.
> 		4. Add blank place before comma if comma when the comma is at
> 		   the beginning of the line.
> Change in v4:
>                  1. Use common clock framework ops to gain apb clock.
>                  2. This patch need rely on clock patch, which patchwork
>                     link was "https://patchwork.kernel.org/project/linux-clk/list/?series=688892".
> Change in v3:
> 		1. NO change, but other patch in this series of patches set
> 		   has changes
> Change in v2:
> 		1. NO change, but other patch in this series of patches set
> 		   has changes
> 
>   MAINTAINERS                          |   6 +
>   arch/loongarch/kernel/time.c         |   4 +-
>   drivers/clocksource/Kconfig          |   9 +
>   drivers/clocksource/Makefile         |   1 +
>   drivers/clocksource/loongson2_hpet.c | 334 +++++++++++++++++++++++++++
>   5 files changed, 353 insertions(+), 1 deletion(-)
>   create mode 100644 drivers/clocksource/loongson2_hpet.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 7afaf6d72800..52519695a458 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -12026,6 +12026,12 @@ F:	Documentation/devicetree/bindings/clock/loongson,ls2k-clk.yaml
>   F:	drivers/clk/clk-loongson2.c
>   F:	include/dt-bindings/clock/loongson,ls2k-clk.h
>   
> +LOONGSON-2 SOC SERIES HPET DRIVER
> +M:	Yinbo Zhu <zhuyinbo@loongson.cn>
> +L:	linux-kernel@vger.kernel.org
> +S:	Maintained
> +F:	drivers/clocksource/loongson2_hpet.c
> +
>   LSILOGIC MPT FUSION DRIVERS (FC/SAS/SPI)
>   M:	Sathya Prakash <sathya.prakash@broadcom.com>
>   M:	Sreekanth Reddy <sreekanth.reddy@broadcom.com>
> diff --git a/arch/loongarch/kernel/time.c b/arch/loongarch/kernel/time.c
> index 09f20bc81798..0d8b37763086 100644
> --- a/arch/loongarch/kernel/time.c
> +++ b/arch/loongarch/kernel/time.c
> @@ -216,7 +216,9 @@ int __init constant_clocksource_init(void)
>   void __init time_init(void)
>   {
>   	of_clk_init(NULL);
> -
> +#ifdef CONFIG_TIMER_PROBE
> +	timer_probe();
> +#endif
>   	if (!cpu_has_cpucfg)
>   		const_clock_freq = cpu_clock_freq;
>   	else
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index 4469e7f555e9..f114ee47e6f7 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -721,4 +721,13 @@ config GOLDFISH_TIMER
>   	help
>   	  Support for the timer/counter of goldfish-rtc
>   
> +config LOONGSON2_HPET
> +	bool "Loongson-2 High Precision Event Timer (HPET)"
> +	select TIMER_PROBE
> +	select TIMER_OF
> +	help
> +	  This option enables Loongson-2 High Precision Event Timer
> +	  (HPET) module driver. It supports the oneshot, the periodic
> +	  modes and high resolution. It is used as a clocksource and
> +	  a clockevent.
>   endmenu
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index 64ab547de97b..1a3abb770f11 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -88,3 +88,4 @@ obj-$(CONFIG_MICROCHIP_PIT64B)		+= timer-microchip-pit64b.o
>   obj-$(CONFIG_MSC313E_TIMER)		+= timer-msc313e.o
>   obj-$(CONFIG_GOLDFISH_TIMER)		+= timer-goldfish.o
>   obj-$(CONFIG_GXP_TIMER)			+= timer-gxp.o
> +obj-$(CONFIG_LOONGSON2_HPET)		+= loongson2_hpet.o
> diff --git a/drivers/clocksource/loongson2_hpet.c b/drivers/clocksource/loongson2_hpet.c
> new file mode 100644
> index 000000000000..9b828f9728ca
> --- /dev/null
> +++ b/drivers/clocksource/loongson2_hpet.c
> @@ -0,0 +1,334 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Author: Yinbo Zhu <zhuyinbo@loongson.cn>
> + * Copyright (C) 2022-2023 Loongson Technology Corporation Limited
> + */
> +
> +#include <linux/init.h>
> +#include <linux/percpu.h>
> +#include <linux/delay.h>
> +#include <linux/spinlock.h>
> +#include <linux/interrupt.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_address.h>
> +#include <linux/clk.h>
> +#include <asm/time.h>
> +
> +/* HPET regs */
> +#define HPET_CFG                0x010
> +#define HPET_STATUS             0x020
> +#define HPET_COUNTER            0x0f0
> +#define HPET_T0_IRS             0x001
> +#define HPET_T0_CFG             0x100
> +#define HPET_T0_CMP             0x108
> +#define HPET_CFG_ENABLE         0x001
> +#define HPET_TN_LEVEL           0x0002
> +#define HPET_TN_ENABLE          0x0004
> +#define HPET_TN_PERIODIC        0x0008
> +#define HPET_TN_SETVAL          0x0040
> +#define HPET_TN_32BIT           0x0100
> +
> +#define HPET_MIN_CYCLES		16
> +#define HPET_MIN_PROG_DELTA	(HPET_MIN_CYCLES * 12)
> +#define HPET_COMPARE_VAL	((hpet_freq + HZ / 2) / HZ)
> +
> +void __iomem			*hpet_mmio_base;
> +unsigned int			hpet_freq;
> +unsigned int			hpet_t0_irq;
> +unsigned int			hpet_irq_flags;
> +unsigned int			hpet_t0_cfg;
> +
> +static DEFINE_SPINLOCK(hpet_lock);
> +DEFINE_PER_CPU(struct clock_event_device, hpet_clockevent_device);
> +
> +static int hpet_read(int offset)
> +{
> +	return readl(hpet_mmio_base + offset);
> +}
> +
> +static void hpet_write(int offset, int data)
> +{
> +	writel(data, hpet_mmio_base + offset);
> +}
> +
> +static void hpet_start_counter(void)
> +{
> +	unsigned int cfg = hpet_read(HPET_CFG);
> +
> +	cfg |= HPET_CFG_ENABLE;
> +	hpet_write(HPET_CFG, cfg);
> +}
> +
> +static void hpet_stop_counter(void)
> +{
> +	unsigned int cfg = hpet_read(HPET_CFG);
> +
> +	cfg &= ~HPET_CFG_ENABLE;
> +	hpet_write(HPET_CFG, cfg);
> +}
> +
> +static void hpet_reset_counter(void)
> +{
> +	hpet_write(HPET_COUNTER, 0);
> +	hpet_write(HPET_COUNTER + 4, 0);
> +}
> +
> +static void hpet_restart_counter(void)
> +{
> +	hpet_stop_counter();
> +	hpet_reset_counter();
> +	hpet_start_counter();
> +}
> +
> +static void hpet_enable_legacy_int(void)
> +{
> +	/* Do nothing on Loongson2 */
> +}
> +
> +static int hpet_set_state_periodic(struct clock_event_device *evt)
> +{
> +	int cfg;
> +
> +	spin_lock(&hpet_lock);
> +
> +	pr_info("set clock event to periodic mode!\n");
> +	/* stop counter */
> +	hpet_stop_counter();
> +	hpet_reset_counter();
> +	hpet_write(HPET_T0_CMP, 0);
> +
> +	/* enables the timer0 to generate a periodic interrupt */
> +	cfg = hpet_read(HPET_T0_CFG);
> +	cfg &= ~HPET_TN_LEVEL;
> +	cfg |= HPET_TN_ENABLE | HPET_TN_PERIODIC | HPET_TN_SETVAL |
> +		HPET_TN_32BIT | hpet_irq_flags;
> +	hpet_write(HPET_T0_CFG, cfg);
> +
> +	/* set the comparator */
> +	hpet_write(HPET_T0_CMP, HPET_COMPARE_VAL);
> +	udelay(1);
> +	hpet_write(HPET_T0_CMP, HPET_COMPARE_VAL);
> +
> +	/* start counter */
> +	hpet_start_counter();
> +
> +	spin_unlock(&hpet_lock);
> +	return 0;
> +}
> +
> +static int hpet_set_state_shutdown(struct clock_event_device *evt)
> +{
> +	int cfg;
> +
> +	spin_lock(&hpet_lock);
> +
> +	cfg = hpet_read(HPET_T0_CFG);
> +	cfg &= ~HPET_TN_ENABLE;
> +	hpet_write(HPET_T0_CFG, cfg);
> +
> +	spin_unlock(&hpet_lock);
> +	return 0;
> +}
> +
> +static int hpet_set_state_oneshot(struct clock_event_device *evt)
> +{
> +	int cfg;
> +
> +	spin_lock(&hpet_lock);
> +
> +	pr_info("set clock event to one shot mode!\n");
> +	cfg = hpet_read(HPET_T0_CFG);
> +	/*
> +	 * set timer0 type
> +	 * 1 : periodic interrupt
> +	 * 0 : non-periodic(oneshot) interrupt
> +	 */
> +	cfg &= ~HPET_TN_PERIODIC;
> +	cfg |= HPET_TN_ENABLE | HPET_TN_32BIT |
> +		hpet_irq_flags;
> +	hpet_write(HPET_T0_CFG, cfg);
> +
> +	/* start counter */
> +	hpet_start_counter();
> +
> +	spin_unlock(&hpet_lock);
> +	return 0;
> +}
> +
> +static int hpet_tick_resume(struct clock_event_device *evt)
> +{
> +	spin_lock(&hpet_lock);
> +	hpet_enable_legacy_int();
> +	spin_unlock(&hpet_lock);
> +
> +	return 0;
> +}
> +
> +static int hpet_next_event(unsigned long delta,
> +		struct clock_event_device *evt)
> +{
> +	u32 cnt;
> +	s32 res;
> +
> +	cnt = hpet_read(HPET_COUNTER);
> +	cnt += (u32) delta;
> +	hpet_write(HPET_T0_CMP, cnt);
> +
> +	res = (s32)(cnt - hpet_read(HPET_COUNTER));
> +
> +	return res < HPET_MIN_CYCLES ? -ETIME : 0;
> +}
> +
> +static irqreturn_t hpet_irq_handler(int irq, void *data)
> +{
> +	int is_irq;
> +	struct clock_event_device *cd;
> +	unsigned int cpu = smp_processor_id();
> +
> +	is_irq = hpet_read(HPET_STATUS);
> +	if (is_irq & HPET_T0_IRS) {
> +		/* clear the TIMER0 irq status register */
> +		hpet_write(HPET_STATUS, HPET_T0_IRS);
> +		cd = &per_cpu(hpet_clockevent_device, cpu);
> +		cd->event_handler(cd);
> +		return IRQ_HANDLED;
> +	}
> +	return IRQ_NONE;
> +}
> +
> +/*
> + * HPET address assignation and irq setting should be done in bios.
> + * But, sometimes bios don't do this, we just setup here directly.
> + */
> +static void hpet_setup(void)
> +{
> +	hpet_enable_legacy_int();
> +}
> +
> +static int hpet_request_irq(struct clock_event_device *cd)
> +{
> +	unsigned long flags = IRQD_NO_BALANCING | IRQF_TIMER;
> +
> +	if (request_irq(cd->irq, hpet_irq_handler, flags, "hpet", NULL)) {
> +		pr_err("Failed to request hpet interrupt\n");
> +		return -1;
> +	}
> +
> +	disable_irq(cd->irq);
> +	irq_set_affinity(cd->irq, cd->cpumask);
> +	enable_irq(cd->irq);
> +
> +	return 0;
> +}
> +
> +static int __init loongson2_hpet_clockevent_init(void)
> +{
> +	unsigned int cpu = smp_processor_id();
> +	struct clock_event_device *cd;
> +
> +	hpet_setup();
> +
> +	cd = &per_cpu(hpet_clockevent_device, cpu);
> +	cd->name = "hpet";
> +	cd->rating = 300;
> +	cd->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
> +	cd->set_state_shutdown = hpet_set_state_shutdown;
> +	cd->set_state_periodic = hpet_set_state_periodic;
> +	cd->set_state_oneshot = hpet_set_state_oneshot;
> +	cd->tick_resume = hpet_tick_resume;
> +	cd->set_next_event = hpet_next_event;
> +	cd->irq = hpet_t0_irq;
> +	cd->cpumask = cpumask_of(cpu);
> +	clockevent_set_clock(cd, hpet_freq);
> +	cd->max_delta_ns = clockevent_delta2ns(0x7fffffff, cd);
> +	cd->max_delta_ticks = 0x7fffffff;
> +	cd->min_delta_ns = clockevent_delta2ns(HPET_MIN_PROG_DELTA, cd);
> +	cd->min_delta_ticks = HPET_MIN_PROG_DELTA;
> +
> +	clockevents_register_device(cd);
> +	if (hpet_request_irq(cd))
> +		return -1;
> +
> +	pr_info("hpet clock event device register\n");
> +
> +	return 0;
> +}
> +
> +static u64 hpet_read_counter(struct clocksource *cs)
> +{
> +	return (u64)hpet_read(HPET_COUNTER);
> +}
> +
> +static void hpet_suspend(struct clocksource *cs)
> +{
> +	hpet_t0_cfg = hpet_read(HPET_T0_CFG);
> +}
> +
> +static void hpet_resume(struct clocksource *cs)
> +{
> +	hpet_write(HPET_T0_CFG, hpet_t0_cfg);
> +	hpet_setup();
> +	hpet_restart_counter();
> +}
> +
> +struct clocksource csrc_hpet = {
> +	.name = "hpet",
> +	.rating = 300,
> +	.read = hpet_read_counter,
> +	.mask = CLOCKSOURCE_MASK(32),
> +	/* oneshot mode work normal with this flag */
> +	.flags = CLOCK_SOURCE_IS_CONTINUOUS,
> +	.suspend = hpet_suspend,
> +	.resume = hpet_resume,
> +	.mult = 0,
> +	.shift = 10,
> +};
> +
> +static int __init loongson2_hpet_clocksource_init(void)
> +{
> +	csrc_hpet.mult = clocksource_hz2mult(hpet_freq, csrc_hpet.shift);
> +
> +	/* start counter */
> +	hpet_start_counter();
> +
> +	return clocksource_register_hz(&csrc_hpet, hpet_freq);
> +}
> +
> +static int __init loongson2_hpet_init(struct device_node *np)
> +{
> +	struct clk *clk;
> +	int ret = -EINVAL;
> +
> +	hpet_mmio_base = of_iomap(np, 0);
> +	if (!hpet_mmio_base) {
> +		pr_err("hpet: unable to map loongson2 hpet registers\n");
> +		return -ENOMEM;
> +	}
> +
> +	hpet_t0_irq = irq_of_parse_and_map(np, 0);
> +	if (hpet_t0_irq <= 0) {
> +		pr_err("hpet: unable to get IRQ from DT, %d\n", hpet_t0_irq);
> +		goto err;
> +	}
> +
> +	clk = of_clk_get(np, 0);
> +	if (IS_ERR(clk))
> +		goto err;
> +
> +	hpet_freq = clk_get_rate(clk);
> +	clk_put(clk);
> +
> +	hpet_irq_flags = HPET_TN_LEVEL;
> +
> +	loongson2_hpet_clocksource_init();
> +
> +	loongson2_hpet_clockevent_init();
> +
> +	return 0;
> +
> +err:
> +	iounmap(hpet_mmio_base);
> +	return ret;
> +}
> +
> +TIMER_OF_DECLARE(loongson2_hpet, "loongson,ls2k-hpet", loongson2_hpet_init);
>