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Message-ID: <3f76f965-7c7b-109e-2ee0-3033e332e84b@linaro.org>
Date:   Tue, 24 Oct 2023 16:56:56 +0200
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Subject: Re: [PATCH v7 2/3] clocksource: Add JH7110 timer driver
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To:     Xingyu Wu <xingyu.wu@starfivetech.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Emil Renner Berthing <emil.renner.berthing@canonical.com>,
        Christophe JAILLET <christophe.jaillet@wanadoo.fr>
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>,
        Walker Chen <walker.chen@starfivetech.com>,
        Samin Guo <samin.guo@starfivetech.com>,
        linux-kernel@vger.kernel.org, Conor Dooley <conor@kernel.org>
References: <20231019053501.46899-1-xingyu.wu@starfivetech.com>
 <20231019053501.46899-3-xingyu.wu@starfivetech.com>
From:   Daniel Lezcano <daniel.lezcano@linaro.org>
In-Reply-To: <20231019053501.46899-3-xingyu.wu@starfivetech.com>
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Hi Xingyu,


On 19/10/2023 07:35, Xingyu Wu wrote:
> Add timer driver for the StarFive JH7110 SoC.

As it is a new timer, please add a proper nice description explaining 
the timer hardware, thanks.

> Signed-off-by: Xingyu Wu <xingyu.wu@starfivetech.com>
> ---
>   MAINTAINERS                        |   7 +
>   drivers/clocksource/Kconfig        |  11 +
>   drivers/clocksource/Makefile       |   1 +
>   drivers/clocksource/timer-jh7110.c | 380 +++++++++++++++++++++++++++++
>   4 files changed, 399 insertions(+)
>   create mode 100644 drivers/clocksource/timer-jh7110.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 7a7bd8bd80e9..91c09b399131 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -20473,6 +20473,13 @@ 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

You may want to use ARCH_STARFIVE only if the platform can make this 
timer optional. Otherwise, set the option from the platform Kconfig and 
put the bool "bla bla" if COMPILE_TEST

> +	select TIMER_OF
> +	select CLKSRC_MMIO
> +	default ARCH_STARFIVE

no "default"

> +	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..71de29a3ec91
> --- /dev/null
> +++ b/drivers/clocksource/timer-jh7110.c
> @@ -0,0 +1,380 @@
> +// 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>

Please double check the headers and remove the pointless ones.


> +/* 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_RELOAD_VALUE	0
> +
> +#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_ENA	BIT(0)
> +#define JH7110_TIMER_INT_CLR_AVA_MASK	BIT(1)
> +
> +struct jh7110_clkevt {
> +	struct clock_event_device evt;
> +	struct clocksource cs;
> +	bool cs_is_valid;
> +	struct clk *clk;
> +	struct reset_control *rst;
> +	u32 rate;
> +	u32 reload_val;
> +	void __iomem *base;
> +	char name[sizeof("jh7110-timer.chX")];
> +};
> +
> +struct jh7110_timer_priv {
> +	struct clk *pclk;
> +	struct reset_control *prst;
> +	struct jh7110_clkevt clkevt[JH7110_TIMER_CH_MAX];

Why do you need several clock events and clock sources ?

[ ... ]


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