Re: [PATCH v7 2/3] clocksource: Add JH7110 timer driver

Xingyu Wu
2023-10-25T08:47:11Z

On 2023/10/24 21:13, 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 | 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
>> + 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..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>
>> +
>> +/* 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")];
>> +};
>
> Maybe sort this by alignment so you save a few bytes. Eg. something like
>
> struct jh7110_clkevt {
> struct clock_event_device evt;
> struct clocksource cs;
> struct clk *clk;
> struct reset_control *rst;
> void __iomem *base;
> u32 rate;
> u32 reload_val;
> bool cs_is_valid;
> char name[sizeof("jh7110-timer.chX")];
> };

Will fix.

>
>> +struct jh7110_timer_priv {
>> + struct clk *pclk;
>> + struct reset_control *prst;
>> + struct jh7110_clkevt clkevt[JH7110_TIMER_CH_MAX];
>> +};
>> +
>> +/* 0:continuous-run mode, 1:single-run mode */
>> +enum jh7110_timer_mode {
>> + JH7110_TIMER_MODE_CONTIN,
>> + JH7110_TIMER_MODE_SINGLE,
>> +};
>> +
>> +/* Interrupt Mask, 0:Unmask, 1:Mask */
>> +enum jh7110_timer_int_mask {
>> + JH7110_TIMER_INT_ENA,
>> + JH7110_TIMER_INT_DIS,
>> +};
>> +
>> +enum jh7110_timer_enable {
>> + JH7110_TIMER_DIS,
>> + JH7110_TIMER_ENA,
>> +};
>> +
>> +static inline struct jh7110_clkevt *to_jh7110_clkevt(struct clock_event_device *evt)
>> +{
>> + return container_of(evt, struct jh7110_clkevt, evt);
>> +}
>> +
>> +/*
>> + * BIT(0): Read value represent channel int status.
>> + * Write 1 to this bit to clear interrupt. Write 0 has no effects.
>> + * BIT(1): "1" means that it is clearing interrupt. BIT(0) can not be written.
>> + */
>> +static inline int jh7110_timer_int_clear(struct jh7110_clkevt *clkevt)
>> +{
>> + u32 value;
>> + int ret;
>> +
>> + /* Waiting interrupt can be cleared */
>> + ret = readl_poll_timeout_atomic(clkevt->base + JH7110_TIMER_INT_CLR, value,
>> + !(value & JH7110_TIMER_INT_CLR_AVA_MASK),
>> + JH7110_DELAY_US, JH7110_TIMEOUT_US);
>> + if (!ret)
>> + writel(JH7110_TIMER_INT_CLR_ENA, clkevt->base + JH7110_TIMER_INT_CLR);
>
> Below you're calling this function in the interrupt handler and the shutdown
> callback, so is it really safe to always enable the interrupt on timeouts?
>
> I think you just want the version below and then let the caller handle
> re-enabling the interrupts on errors if needed. (While you're at it you can
> remove the inline and let the compiler decide, which is does anyway.)
>
> static int jh7110_timer_int_clear(struct jh7110_clkevt *clkevt)
> {
> u32 value;
>
> /* Waiting interrupt can be cleared */
> return readl_poll_timeout_atomic(clkevt->base + JH7110_TIMER_INT_CLR, value,
> !(value & JH7110_TIMER_INT_CLR_AVA_MASK),
> JH7110_DELAY_US, JH7110_TIMEOUT_US);
> }
>

So I drop this function and use the writel() of cleaning the interrupt directly in the interrupt handler.
And drop the inline.

>> +
>> + return ret;
>> +}
>> +
>> +static int jh7110_timer_start(struct jh7110_clkevt *clkevt)
>> +{
>> + int ret;
>> +
>> + /* Disable and clear interrupt first */
>> + writel(JH7110_TIMER_INT_DIS, clkevt->base + JH7110_TIMER_INT_MASK);
>> + ret = jh7110_timer_int_clear(clkevt);
>> + if (ret)
>> + return ret;
>> +
>> + writel(JH7110_TIMER_INT_ENA, clkevt->base + JH7110_TIMER_INT_MASK);
>> + writel(JH7110_TIMER_ENA, clkevt->base + JH7110_TIMER_ENABLE);
>> +
>> + return 0;
>> +}
>> +
>> +static int jh7110_timer_shutdown(struct clock_event_device *evt)
>> +{
>> + struct jh7110_clkevt *clkevt = to_jh7110_clkevt(evt);
>> +
>> + writel(JH7110_TIMER_DIS, clkevt->base + JH7110_TIMER_ENABLE);
>> + return jh7110_timer_int_clear(clkevt);
>> +}
>> +
>> +static void jh7110_timer_suspend(struct clock_event_device *evt)
>> +{
>> + struct jh7110_clkevt *clkevt = to_jh7110_clkevt(evt);
>> +
>> + clkevt->reload_val = readl(clkevt->base + JH7110_TIMER_LOAD);
>> + jh7110_timer_shutdown(evt);
>> +}
>> +
>> +static void jh7110_timer_resume(struct clock_event_device *evt)
>> +{
>> + struct jh7110_clkevt *clkevt = to_jh7110_clkevt(evt);
>> +
>> + writel(clkevt->reload_val, clkevt->base + JH7110_TIMER_LOAD);
>> + writel(JH7110_TIMER_RELOAD_VALUE, clkevt->base + JH7110_TIMER_RELOAD);
>> + jh7110_timer_start(clkevt);
>> +}
>> +
>> +static int jh7110_timer_tick_resume(struct clock_event_device *evt)
>> +{
>> + jh7110_timer_resume(evt);
>> +
>> + return 0;
>> +}
>
> Here you probably want it the other way around, so you handle possible errors
> from jh7110_timer_start() properly. Eg.
>
> static int jh7110_timer_tick_resume(struct clock_event_device *evt)
> {
> struct jh7110_clkevt *clkevt = to_jh7110_clkevt(evt);
>
> writel(clkevt->reload_val, clkevt->base + JH7110_TIMER_LOAD);
> writel(JH7110_TIMER_RELOAD_VALUE, clkevt->base + JH7110_TIMER_RELOAD);
> return jh7110_timer_start(clkevt);
> }
>
> static void jh7110_timer_resume(struct clock_event_device *evt)
> {
> jh7110_timer_tick_resume(evt);
> }
>

OK, so this makes the best use of the return value of jh7110_timer_start().
Will fix.

>> +/* IRQ handler for the timer */
>> +static irqreturn_t jh7110_timer_interrupt(int irq, void *priv)
>> +{
>> + struct clock_event_device *evt = (struct clock_event_device *)priv;
>
> This cast is unnecessary and also calling the variable priv makes you think
> it's a struct jh7110_timer_priv, but the interrupt is registered with a
> struct clock_event_device pointer.
>
>> + struct jh7110_clkevt *clkevt = to_jh7110_clkevt(evt);
>
> But here you're immediately casting it to a struct jh7110_clkevt pointer. So
> why not just register the interrupt with the struct jh7110_clkevt pointer, do
>
> struct jh7110_clkevt *clkevt = data;
>

You are right. Will fix.

>> +
>> + if (jh7110_timer_int_clear(clkevt))
>> + return IRQ_NONE;
>> +
>> + if (evt->event_handler)
>> + evt->event_handler(evt);
>
> ..and just use clkevt->evt.event_handler and &clkevt->evt here?

Will fix.

>
>> +
>> + return IRQ_HANDLED;
>> +}
>> +
>> +static int jh7110_timer_set_periodic(struct clock_event_device *evt)
>> +{
>> + struct jh7110_clkevt *clkevt = to_jh7110_clkevt(evt);
>> + u32 periodic = DIV_ROUND_CLOSEST(clkevt->rate, HZ);
>> +
>> + writel(JH7110_TIMER_MODE_CONTIN, clkevt->base + JH7110_TIMER_CTL);
>> + writel(periodic, clkevt->base + JH7110_TIMER_LOAD);
>> +
>> + return jh7110_timer_start(clkevt);
>> +}
>> +
>> +static int jh7110_timer_set_oneshot(struct clock_event_device *evt)
>> +{
>> + struct jh7110_clkevt *clkevt = to_jh7110_clkevt(evt);
>> +
>> + writel(JH7110_TIMER_MODE_SINGLE, clkevt->base + JH7110_TIMER_CTL);
>> + writel(JH7110_TIMER_MAX_TICKS, clkevt->base + JH7110_TIMER_LOAD);
>> +
>> + return jh7110_timer_start(clkevt);
>> +}
>> +
>> +static int jh7110_timer_set_next_event(unsigned long next,
>> + struct clock_event_device *evt)
>> +{
>> + struct jh7110_clkevt *clkevt = to_jh7110_clkevt(evt);
>> +
>> + writel(JH7110_TIMER_MODE_SINGLE, clkevt->base + JH7110_TIMER_CTL);
>> + writel(next, clkevt->base + JH7110_TIMER_LOAD);
>> +
>> + return jh7110_timer_start(clkevt);
>> +}
>> +
>> +static void jh7110_set_clockevent(struct clock_event_device *evt)
>> +{
>> + evt->features = CLOCK_EVT_FEAT_PERIODIC |
>> + CLOCK_EVT_FEAT_ONESHOT |
>> + CLOCK_EVT_FEAT_DYNIRQ;
>> + evt->set_state_shutdown = jh7110_timer_shutdown;
>> + evt->set_state_periodic = jh7110_timer_set_periodic;
>> + evt->set_state_oneshot = jh7110_timer_set_oneshot;
>> + evt->set_state_oneshot_stopped = jh7110_timer_shutdown;
>> + evt->tick_resume = jh7110_timer_tick_resume;
>> + evt->set_next_event = jh7110_timer_set_next_event;
>> + evt->suspend = jh7110_timer_suspend;
>> + evt->resume = jh7110_timer_resume;
>> + evt->rating = JH7110_CLOCKEVENT_RATING;
>> +}
>> +
>> +static u64 jh7110_timer_clocksource_read(struct clocksource *cs)
>> +{
>> + struct jh7110_clkevt *clkevt = container_of(cs, struct jh7110_clkevt, cs);
>> +
>> + return (u64)readl(clkevt->base + JH7110_TIMER_VALUE);
>> +}
>> +
>> +static int jh7110_clocksource_init(struct jh7110_clkevt *clkevt)
>> +{
>> + int ret;
>> +
>> + clkevt->cs.name = clkevt->name;
>> + clkevt->cs.rating = JH7110_CLOCK_SOURCE_RATING;
>> + clkevt->cs.read = jh7110_timer_clocksource_read;
>> + clkevt->cs.mask = CLOCKSOURCE_MASK(JH7110_VALID_BITS);
>> + clkevt->cs.flags = CLOCK_SOURCE_IS_CONTINUOUS;
>> +
>> + ret = clocksource_register_hz(&clkevt->cs, clkevt->rate);
>> + if (ret)
>> + return ret;
>> +
>> + clkevt->cs_is_valid = true; /* clocksource register done */
>> + writel(JH7110_TIMER_MODE_CONTIN, clkevt->base + JH7110_TIMER_CTL);
>> + writel(JH7110_TIMER_MAX_TICKS, clkevt->base + JH7110_TIMER_LOAD);
>> +
>> + return jh7110_timer_start(clkevt);
>> +}
>> +
>> +static void jh7110_clockevents_register(struct jh7110_clkevt *clkevt)
>> +{
>> + clkevt->rate = clk_get_rate(clkevt->clk);
>> +
>> + jh7110_set_clockevent(&clkevt->evt);
>> + clkevt->evt.name = clkevt->name;
>> + clkevt->evt.cpumask = cpu_possible_mask;
>> +
>> + clockevents_config_and_register(&clkevt->evt, clkevt->rate,
>> + JH7110_TIMER_MIN_TICKS, JH7110_TIMER_MAX_TICKS);
>> +}
>> +
>> +static void jh7110_timer_release(void *data)
>> +{
>> + struct jh7110_timer_priv *priv = data;
>> + int i;
>> +
>> + for (i = 0; i < JH7110_TIMER_CH_MAX; i++) {
>> + /* Disable each channel of timer */
>> + if (priv->clkevt[i].base)
>> + writel(JH7110_TIMER_DIS, priv->clkevt[i].base + JH7110_TIMER_ENABLE);
>> +
>> + /* Avoid no initialization in the loop of the probe */
>> + if (!IS_ERR_OR_NULL(priv->clkevt[i].rst))
>> + reset_control_assert(priv->clkevt[i].rst);
>> +
>> + if (priv->clkevt[i].cs_is_valid)
>> + clocksource_unregister(&priv->clkevt[i].cs);
>> + }
>> +
>> + reset_control_assert(priv->prst);
>> +}
>> +
>> +static int jh7110_timer_probe(struct platform_device *pdev)
>> +{
>> + struct jh7110_timer_priv *priv;
>> + struct jh7110_clkevt *clkevt;
>> + char name[sizeof("chX")];
>> + int ch;
>> + int ret;
>> + void __iomem *base;
>> +
>> + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
>> + if (!priv)
>> + return -ENOMEM;
>> +
>> + 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");
>> +
>> + priv->prst = devm_reset_control_get_exclusive(&pdev->dev, "apb");
>> + if (IS_ERR(priv->prst))
>> + return dev_err_probe(&pdev->dev, PTR_ERR(priv->prst),
>> + "failed to get apb reset\n");
>> +
>> + priv->pclk = devm_clk_get_enabled(&pdev->dev, "apb");
>> + if (IS_ERR(priv->pclk))
>> + return dev_err_probe(&pdev->dev, PTR_ERR(priv->pclk),
>> + "failed to get & enable apb clock\n");
>
> priv->pclk is set here, but never read anywhere. Just remove it from the struct
> and use a local variable here.

Sorry, I will drop it and use a local variable.

>
>> +
>> + ret = reset_control_deassert(priv->prst);
>> + if (ret)
>> + return dev_err_probe(&pdev->dev, ret, "failed to deassert apb reset\n");
>> +
>> + ret = devm_add_action_or_reset(&pdev->dev, jh7110_timer_release, priv);
>> + if (ret)
>> + return ret;
>> +
>> + for (ch = 0; ch < JH7110_TIMER_CH_MAX; ch++) {
>> + clkevt = &priv->clkevt[ch];
>> + snprintf(name, sizeof(name), "ch%d", ch);
>> +
>> + clkevt->base = base + JH7110_TIMER_CH_BASE(ch);
>> + /* Ensure timer is disabled */
>> + writel(JH7110_TIMER_DIS, clkevt->base + JH7110_TIMER_ENABLE);
>> +
>> + clkevt->rst = devm_reset_control_get_exclusive(&pdev->dev, name);
>> + if (IS_ERR(clkevt->rst))
>> + return PTR_ERR(clkevt->rst);
>> +
>> + clkevt->clk = devm_clk_get_enabled(&pdev->dev, name);
>> + if (IS_ERR(clkevt->clk))
>> + return PTR_ERR(clkevt->clk);
>> +
>> + ret = reset_control_deassert(clkevt->rst);
>> + if (ret)
>> + return ret;
>> +
>> + clkevt->evt.irq = platform_get_irq(pdev, ch);
>> + if (clkevt->evt.irq < 0)
>> + return clkevt->evt.irq;
>> +
>> + snprintf(clkevt->name, sizeof(clkevt->name), "jh7110-timer.ch%d", ch);
>> + jh7110_clockevents_register(clkevt);
>> +
>> + ret = devm_request_irq(&pdev->dev, clkevt->evt.irq, jh7110_timer_interrupt,
>> + IRQF_TIMER | IRQF_IRQPOLL,
>> + clkevt->name, &clkevt->evt);
>> + if (ret)
>> + return ret;
>> +
>> + ret = jh7110_clocksource_init(clkevt);
>> + 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

Best Regards,
Xingyu Wu