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From:   Emil Renner Berthing <emil.renner.berthing@canonical.com>
In-Reply-To: <4503625e-c696-4ed5-84b3-398bbb243162@starfivetech.com>
References: <20231012081015.33121-1-xingyu.wu@starfivetech.com>
 <20231012081015.33121-3-xingyu.wu@starfivetech.com> <CAJM55Z8_AwYdgBLcAs=C9W2UtZ0CVecGMS_D198A8j4DYFFxBw@mail.gmail.com>
 <ec78d27e-8cc4-484e-aac9-e253498aa946@starfivetech.com> <CAJM55Z9HCLWAB0G-froC1bEDk=DERQhKvSD7w+eQ_6a3J+74wg@mail.gmail.com>
 <4503625e-c696-4ed5-84b3-398bbb243162@starfivetech.com>
Mime-Version: 1.0
Date:   Mon, 16 Oct 2023 03:20:05 -0700
Message-ID: <CAJM55Z9geA=4G1KYdzafee7TziDO2-AZDRgg-hJDJoJgv+MtqQ@mail.gmail.com>
Subject: Re: [PATCH v6 2/3] clocksource: Add JH7110 timer driver
To:     Xingyu Wu <xingyu.wu@starfivetech.com>,
        Emil Renner Berthing <emil.renner.berthing@canonical.com>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Walker Chen <walker.chen@starfivetech.com>
Cc:     linux-riscv@lists.infradead.org, devicetree@vger.kernel.org,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Samin Guo <samin.guo@starfivetech.com>,
        linux-kernel@vger.kernel.org, Conor Dooley <conor@kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Xingyu Wu wrote:
> On 2023/10/16 17:23, Emil Renner Berthing wrote:
> > Xingyu Wu wrote:
> >> On 2023/10/13 19:34, Emil Renner Berthing wrote:
> >> > Xingyu Wu wrote:
> >> >> Add timer driver for the StarFive JH7110 SoC.
> >> >>
> >> >> Signed-off-by: Xingyu Wu <xingyu.wu@starfivetech.com>
> >> >> ---
> >> >>  MAINTAINERS                        |   7 +
> >> >>  drivers/clocksource/Kconfig        |  11 +
> >> >>  drivers/clocksource/Makefile       |   1 +
> >> >>  drivers/clocksource/timer-jh7110.c | 387 +++++++++++++++++++++++++++++
> >> >>  4 files changed, 406 insertions(+)
> >> >>  create mode 100644 drivers/clocksource/timer-jh7110.c
> >> >>
> >> >> diff --git a/MAINTAINERS b/MAINTAINERS
> >> >> index 6c4cce45a09d..1525f031d4a2 100644
> >> >> --- a/MAINTAINERS
> >> >> +++ b/MAINTAINERS
> >> >> @@ -20472,6 +20472,13 @@ S:	Maintained
> >> >>  F:	Documentation/devicetree/bindings/sound/starfive,jh7110-tdm.yaml
> >> >>  F:	sound/soc/starfive/jh7110_tdm.c
> >> >>
> >> >> +STARFIVE JH7110 TIMER DRIVER
> >> >> +M:	Samin Guo <samin.guo@starfivetech.com>
> >> >> +M:	Xingyu Wu <xingyu.wu@starfivetech.com>
> >> >> +S:	Supported
> >> >> +F:	Documentation/devicetree/bindings/timer/starfive,jh7110-timer.yaml
> >> >> +F:	drivers/clocksource/timer-jh7110.c
> >> >> +
> >> >>  STARFIVE JH71X0 CLOCK DRIVERS
> >> >>  M:	Emil Renner Berthing <kernel@esmil.dk>
> >> >>  M:	Hal Feng <hal.feng@starfivetech.com>
> >> >> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> >> >> index 0ba0dc4ecf06..821abcc1e517 100644
> >> >> --- a/drivers/clocksource/Kconfig
> >> >> +++ b/drivers/clocksource/Kconfig
> >> >> @@ -641,6 +641,17 @@ config RISCV_TIMER
> >> >>  	  is accessed via both the SBI and the rdcycle instruction.  This is
> >> >>  	  required for all RISC-V systems.
> >> >>
> >> >> +config STARFIVE_JH7110_TIMER
> >> >> +	bool "Timer for the STARFIVE JH7110 SoC"
> >> >> +	depends on ARCH_STARFIVE || COMPILE_TEST
> >> >> +	select TIMER_OF
> >> >> +	select CLKSRC_MMIO
> >> >> +	default ARCH_STARFIVE
> >> >> +	help
> >> >> +	  This enables the timer for StarFive JH7110 SoC. On RISC-V platform,
> >> >> +	  the system has started RISCV_TIMER, but you can also use this timer
> >> >> +	  which can provide four channels to do a lot more things on JH7110 SoC.
> >> >> +
> >> >>  config CLINT_TIMER
> >> >>  	bool "CLINT Timer for the RISC-V platform" if COMPILE_TEST
> >> >>  	depends on GENERIC_SCHED_CLOCK && RISCV
> >> >> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> >> >> index 368c3461dab8..b66ac05ec086 100644
> >> >> --- a/drivers/clocksource/Makefile
> >> >> +++ b/drivers/clocksource/Makefile
> >> >> @@ -80,6 +80,7 @@ obj-$(CONFIG_INGENIC_TIMER)		+= ingenic-timer.o
> >> >>  obj-$(CONFIG_CLKSRC_ST_LPC)		+= clksrc_st_lpc.o
> >> >>  obj-$(CONFIG_X86_NUMACHIP)		+= numachip.o
> >> >>  obj-$(CONFIG_RISCV_TIMER)		+= timer-riscv.o
> >> >> +obj-$(CONFIG_STARFIVE_JH7110_TIMER)	+= timer-jh7110.o
> >> >>  obj-$(CONFIG_CLINT_TIMER)		+= timer-clint.o
> >> >>  obj-$(CONFIG_CSKY_MP_TIMER)		+= timer-mp-csky.o
> >> >>  obj-$(CONFIG_GX6605S_TIMER)		+= timer-gx6605s.o
> >> >> diff --git a/drivers/clocksource/timer-jh7110.c b/drivers/clocksource/timer-jh7110.c
> >> >> new file mode 100644
> >> >> index 000000000000..914424368290
> >> >> --- /dev/null
> >> >> +++ b/drivers/clocksource/timer-jh7110.c
> >> >> @@ -0,0 +1,387 @@
> >> >> +// SPDX-License-Identifier: GPL-2.0
> >> >> +/*
> >> >> + * Starfive JH7110 Timer driver
> >> >> + *
> >> >> + * Copyright (C) 2022-2023 StarFive Technology Co., Ltd.
> >> >> + *
> >> >> + * Author:
> >> >> + * Xingyu Wu <xingyu.wu@starfivetech.com>
> >> >> + * Samin Guo <samin.guo@starfivetech.com>
> >> >> + */
> >> >> +
> >> >> +#include <linux/clk.h>
> >> >> +#include <linux/clockchips.h>
> >> >> +#include <linux/clocksource.h>
> >> >> +#include <linux/err.h>
> >> >> +#include <linux/interrupt.h>
> >> >> +#include <linux/io.h>
> >> >> +#include <linux/iopoll.h>
> >> >> +#include <linux/irq.h>
> >> >> +#include <linux/kernel.h>
> >> >> +#include <linux/module.h>
> >> >> +#include <linux/of.h>
> >> >> +#include <linux/of_device.h>
> >> >> +#include <linux/platform_device.h>
> >> >> +#include <linux/reset.h>
> >> >> +#include <linux/sched_clock.h>
> >> >> +
> >> >> +/* Bias: Ch0-0x0, Ch1-0x40, Ch2-0x80, and so on. */
> >> >> +#define JH7110_TIMER_CH_LEN		0x40
> >> >> +#define JH7110_TIMER_CH_BASE(x)		((x) * JH7110_TIMER_CH_LEN)
> >> >> +#define JH7110_TIMER_CH_MAX		4
> >> >> +
> >> >> +#define JH7110_CLOCK_SOURCE_RATING	200
> >> >> +#define JH7110_VALID_BITS		32
> >> >> +#define JH7110_DELAY_US			0
> >> >> +#define JH7110_TIMEOUT_US		10000
> >> >> +#define JH7110_CLOCKEVENT_RATING	300
> >> >> +#define JH7110_TIMER_MAX_TICKS		0xffffffff
> >> >> +#define JH7110_TIMER_MIN_TICKS		0xf
> >> >> +#define JH7110_TIMER_NAME_NUM		19
> >> >> +
> >> >> +#define JH7110_TIMER_INT_STATUS		0x00 /* RO[0:4]: Interrupt Status for channel0~4 */
> >> >> +#define JH7110_TIMER_CTL		0x04 /* RW[0]: 0-continuous run, 1-single run */
> >> >> +#define JH7110_TIMER_LOAD		0x08 /* RW: load value to counter */
> >> >> +#define JH7110_TIMER_ENABLE		0x10 /* RW[0]: timer enable register */
> >> >> +#define JH7110_TIMER_RELOAD		0x14 /* RW: write 1 or 0 both reload counter */
> >> >> +#define JH7110_TIMER_VALUE		0x18 /* RO: timer value register */
> >> >> +#define JH7110_TIMER_INT_CLR		0x20 /* RW: timer interrupt clear register */
> >> >> +#define JH7110_TIMER_INT_MASK		0x24 /* RW[0]: timer interrupt mask register */
> >> >> +#define JH7110_TIMER_INT_CLR_AVA_MASK	BIT(1)
> >> >> +
> >> >> +struct jh7110_clkevt {
> >> >> +	struct clock_event_device evt;
> >> >> +	struct clocksource cs;
> >> >> +	struct clk *clk;
> >> >> +	char name[JH7110_TIMER_NAME_NUM];
> >> >
> >> > Instead of this define maybe just use something like
> >> >
> >> > 	char name[sizeof("jh7110-timer.chX")];
> >> >
> >>
> >> Will fix.
> >>
> >> >> +	int irq;
> >> >
> >> > You wrote that you "dropped the extra copy of irq", but here you didn't.
> >>
> >> What I mean is to drop the local variable of irq in the probe. Do you mean to use a local variable instead this in the probe?
> >
> > No, what I mean is that this field is no longer used, so you can delete it.
> >
>
> OK, drop it here.
>
> >>
> >> >> +
> >> >> +static int jh7110_timer_probe(struct platform_device *pdev)
> >> >> +{
> >> >> +	struct jh7110_clkevt *clkevt[JH7110_TIMER_CH_MAX];
> >> >> +	char name[4];
> >> >> +	struct clk *pclk;
> >> >> +	struct reset_control *rst;
> >> >> +	int ch;
> >> >> +	int ret;
> >> >> +	void __iomem *base
> >> >> +
> >> >> +	base = devm_platform_ioremap_resource(pdev, 0);
> >> >> +	if (IS_ERR(base))
> >> >> +		return dev_err_probe(&pdev->dev, PTR_ERR(base),
> >> >> +				     "failed to map registers\n");
> >> >> +
> >> >> +	rst = devm_reset_control_get_exclusive(&pdev->dev, "apb");
> >> >> +	if (IS_ERR(rst))
> >> >> +		return dev_err_probe(&pdev->dev, PTR_ERR(rst), "failed to get apb reset\n");
> >> >> +
> >> >> +	pclk = devm_clk_get_enabled(&pdev->dev, "apb");
> >> >> +	if (IS_ERR(pclk))
> >> >> +		return dev_err_probe(&pdev->dev, PTR_ERR(pclk),
> >> >> +				     "failed to get & enable apb clock\n");
> >> >> +
> >> >> +	ret = reset_control_deassert(rst);
> >> >> +	if (ret)
> >> >> +		return dev_err_probe(&pdev->dev, ret, "failed to deassert apb reset\n");
> >> >> +
> >> >> +	for (ch = 0; ch < JH7110_TIMER_CH_MAX; ch++) {
> >> >> +		clkevt[ch] = devm_kzalloc(&pdev->dev, sizeof(*clkevt[ch]), GFP_KERNEL);
> >> >> +		if (!clkevt[ch])
> >> >> +			return -ENOMEM;
> >> >> +
> >> >> +		snprintf(name, sizeof(name), "ch%d", ch);
> >> >> +
> >> >> +		clkevt[ch]->base = base + JH7110_TIMER_CH_BASE(ch);
> >> >> +		/* Ensure timer is disabled */
> >> >> +		jh7110_timer_disable(clkevt[ch]);
> >> >> +
> >> >> +		rst = devm_reset_control_get_exclusive(&pdev->dev, name);
> >> >> +		if (IS_ERR(rst))
> >> >> +			return PTR_ERR(rst);
> >> >> +
> >> >> +		clkevt[ch]->clk = devm_clk_get_enabled(&pdev->dev, name);
> >> >> +		if (IS_ERR(clkevt[ch]->clk))
> >> >> +			return PTR_ERR(clkevt[ch]->clk);
> >> >> +
> >> >> +		ret = reset_control_deassert(rst);
> >> >> +		if (ret)
> >> >> +			return ret;
> >> >> +
> >> >> +		clkevt[ch]->evt.irq = platform_get_irq(pdev, ch);
> >> >> +		if (clkevt[ch]->evt.irq < 0)
> >> >> +			return clkevt[ch]->evt.irq;
> I should use a local variable of irq instead here. Right?

No, I don't think so.

> >> >> +
> >> >> +		snprintf(clkevt[ch]->name, sizeof(clkevt[ch]->name), "%s.ch%d", pdev->name, ch);
> >> >> +		jh7110_clockevents_register(clkevt[ch]);
> >> >> +
> >> >> +		ret = devm_request_irq(&pdev->dev, clkevt[ch]->evt.irq, jh7110_timer_interrupt,
> >> >> +				       IRQF_TIMER | IRQF_IRQPOLL,
> >> >> +				       clkevt[ch]->name, &clkevt[ch]->evt);
> >> >> +		if (ret)
> >> >> +			return ret;
> >> >> +
> >> >> +		ret = jh7110_clocksource_init(clkevt[ch]);
> >> >> +		if (ret)
> >> >> +			return ret;
> >> >> +	}
> >> >> +
> >> >> +	return 0;
> >> >> +}
> >> >> +
> >> >> +static const struct of_device_id jh7110_timer_match[] = {
> >> >> +	{ .compatible = "starfive,jh7110-timer", },
> >> >> +	{ /* sentinel */ }
> >> >> +};
> >> >> +MODULE_DEVICE_TABLE(of, jh7110_timer_match);
> >> >> +
> >> >> +static struct platform_driver jh7110_timer_driver = {
> >> >> +	.probe = jh7110_timer_probe,
> >> >> +	.driver = {
> >> >> +		.name = "jh7110-timer",
> >> >> +		.of_match_table = jh7110_timer_match,
> >> >> +	},
> >> >> +};
> >> >> +module_platform_driver(jh7110_timer_driver);
> >> >> +
> >> >> +MODULE_AUTHOR("Xingyu Wu <xingyu.wu@starfivetech.com>");
> >> >> +MODULE_DESCRIPTION("StarFive JH7110 timer driver");
> >> >> +MODULE_LICENSE("GPL");
> >> >> --
> >> >> 2.25.1