Message-ID: <85988378-0c88-6b71-00df-0700a7b4cdf7@nvidia.com>
Date:   Fri, 1 Feb 2019 13:54:52 +0000
From:   Jon Hunter <jonathanh@...dia.com>
To:     Dmitry Osipenko <digetx@...il.com>, Joseph Lo <josephl@...dia.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Thomas Gleixner <tglx@...utronix.de>
CC:     <linux-tegra@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, Thierry Reding <treding@...dia.com>
Subject: Re: [PATCH V5 2/7] clocksource: tegra: add Tegra210 timer support


On 01/02/2019 13:11, Dmitry Osipenko wrote:
> 01.02.2019 16:06, Dmitry Osipenko пишет:
>> 01.02.2019 6:36, Joseph Lo пишет:
>>> Add support for the Tegra210 timer that runs at oscillator clock
>>> (TMR10-TMR13). We need these timers to work as clock event device and to
>>> replace the ARMv8 architected timer due to it can't survive across the
>>> power cycle of the CPU core or CPUPORESET signal. So it can't be a wake-up
>>> source when CPU suspends in power down state.
>>>
>>> Also convert the original driver to use timer-of API.
>>>
>>> Cc: Daniel Lezcano <daniel.lezcano@...aro.org>
>>> Cc: Thomas Gleixner <tglx@...utronix.de>
>>> Cc: linux-kernel@...r.kernel.org
>>> Signed-off-by: Joseph Lo <josephl@...dia.com>
>>> Acked-by: Thierry Reding <treding@...dia.com>
>>> ---
>>> v5:
>>>  * add ack tag from Thierry
>>> v4:
>>>  * merge timer-tegra210.c in previous version into timer-tegra20.c
>>> v3:
>>>  * use timer-of API
>>> v2:
>>>  * add error clean-up code
>>> ---
>>>  drivers/clocksource/Kconfig         |   2 +-
>>>  drivers/clocksource/timer-tegra20.c | 369 ++++++++++++++++++++--------
>>>  include/linux/cpuhotplug.h          |   1 +
>>>  3 files changed, 272 insertions(+), 100 deletions(-)
>>>
>>> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
>>> index a9e26f6a81a1..6af78534a285 100644
>>> --- a/drivers/clocksource/Kconfig
>>> +++ b/drivers/clocksource/Kconfig
>>> @@ -131,7 +131,7 @@ config SUN5I_HSTIMER
>>>  config TEGRA_TIMER
>>>  	bool "Tegra timer driver" if COMPILE_TEST
>>>  	select CLKSRC_MMIO
>>> -	depends on ARM
>>> +	select TIMER_OF
>>>  	help
>>>  	  Enables support for the Tegra driver.
>>>  
>>> diff --git a/drivers/clocksource/timer-tegra20.c b/drivers/clocksource/timer-tegra20.c
>>> index 4293943f4e2b..96a809341c9b 100644
>>> --- a/drivers/clocksource/timer-tegra20.c
>>> +++ b/drivers/clocksource/timer-tegra20.c
>>> @@ -15,21 +15,24 @@
>>>   *
>>>   */
>>>  
>>> -#include <linux/init.h>
>>> +#include <linux/clk.h>
>>> +#include <linux/clockchips.h>
>>> +#include <linux/cpu.h>
>>> +#include <linux/cpumask.h>
>>> +#include <linux/delay.h>
>>>  #include <linux/err.h>
>>> -#include <linux/time.h>
>>>  #include <linux/interrupt.h>
>>> -#include <linux/irq.h>
>>> -#include <linux/clockchips.h>
>>> -#include <linux/clocksource.h>
>>> -#include <linux/clk.h>
>>> -#include <linux/io.h>
>>>  #include <linux/of_address.h>
>>>  #include <linux/of_irq.h>
>>> -#include <linux/sched_clock.h>
>>> -#include <linux/delay.h>
>>> +#include <linux/percpu.h>
>>> +#include <linux/syscore_ops.h>
>>> +#include <linux/time.h>
>>> +
>>> +#include "timer-of.h"
>>>  
>>> +#ifdef CONFIG_ARM
>>>  #include <asm/mach/time.h>
>>> +#endif
>>>  
>>>  #define RTC_SECONDS            0x08
>>>  #define RTC_SHADOW_SECONDS     0x0c
>>> @@ -43,70 +46,147 @@
>>>  #define TIMER2_BASE 0x8
>>>  #define TIMER3_BASE 0x50
>>>  #define TIMER4_BASE 0x58
>>> -
>>> -#define TIMER_PTV 0x0
>>> -#define TIMER_PCR 0x4
>>> -
>>> +#define TIMER10_BASE 0x90
>>> +
>>> +#define TIMER_PTV		0x0
>>> +#define TIMER_PTV_EN		BIT(31)
>>> +#define TIMER_PTV_PER		BIT(30)
>>> +#define TIMER_PCR		0x4
>>> +#define TIMER_PCR_INTR_CLR	BIT(30)
>>> +
>>> +#ifdef CONFIG_ARM
>>> +#define TIMER_BASE TIMER3_BASE
>>> +#else
>>> +#define TIMER_BASE TIMER10_BASE
>>> +#endif
>>> +#define TIMER10_IRQ_IDX		10
>>> +#define TIMER_FOR_CPU(cpu) (TIMER_BASE + (cpu) * 8)
>>> +#define IRQ_IDX_FOR_CPU(cpu)	(TIMER10_IRQ_IDX + cpu)
>>> +
>>> +static u32 usec_config;
>>>  static void __iomem *timer_reg_base;
>>> +#ifdef CONFIG_ARM
>>>  static void __iomem *rtc_base;
>>> -
>>>  static struct timespec64 persistent_ts;
>>>  static u64 persistent_ms, last_persistent_ms;
>>> -
>>>  static struct delay_timer tegra_delay_timer;
>>> -
>>> -#define timer_writel(value, reg) \
>>> -	writel_relaxed(value, timer_reg_base + (reg))
>>> -#define timer_readl(reg) \
>>> -	readl_relaxed(timer_reg_base + (reg))
>>> +#endif
>>>  
>>>  static int tegra_timer_set_next_event(unsigned long cycles,
>>>  					 struct clock_event_device *evt)
>>>  {
>>> -	u32 reg;
>>> +	void __iomem *reg_base = timer_of_base(to_timer_of(evt));
>>>  
>>> -	reg = 0x80000000 | ((cycles > 1) ? (cycles-1) : 0);
>>> -	timer_writel(reg, TIMER3_BASE + TIMER_PTV);
>>> +	writel(TIMER_PTV_EN |
>>> +	       ((cycles > 1) ? (cycles - 1) : 0), /* n+1 scheme */
>>> +	       reg_base + TIMER_PTV);
>>>  
>>>  	return 0;
>>>  }
>>>  
>>> -static inline void timer_shutdown(struct clock_event_device *evt)
>>> +static int tegra_timer_shutdown(struct clock_event_device *evt)
>>>  {
>>> -	timer_writel(0, TIMER3_BASE + TIMER_PTV);
>>> +	void __iomem *reg_base = timer_of_base(to_timer_of(evt));
>>> +
>>> +	writel(0, reg_base + TIMER_PTV);
>>> +
>>> +	return 0;
>>>  }
>>>  
>>> -static int tegra_timer_shutdown(struct clock_event_device *evt)
>>> +static int tegra_timer_set_periodic(struct clock_event_device *evt)
>>>  {
>>> -	timer_shutdown(evt);
>>> +	void __iomem *reg_base = timer_of_base(to_timer_of(evt));
>>> +
>>> +	writel(TIMER_PTV_EN | TIMER_PTV_PER |
>>> +	       ((timer_of_rate(to_timer_of(evt)) / HZ) - 1),
>>> +	       reg_base + TIMER_PTV);
>>> +
>>>  	return 0;
>>>  }
>>>  
>>> -static int tegra_timer_set_periodic(struct clock_event_device *evt)
>>> +static irqreturn_t tegra_timer_isr(int irq, void *dev_id)
>>>  {
>>> -	u32 reg = 0xC0000000 | ((1000000 / HZ) - 1);
>>> +	struct clock_event_device *evt = (struct clock_event_device *)dev_id;
>>> +	void __iomem *reg_base = timer_of_base(to_timer_of(evt));
>>> +
>>> +	writel(TIMER_PCR_INTR_CLR, reg_base + TIMER_PCR);
>>> +	evt->event_handler(evt);
>>> +
>>> +	return IRQ_HANDLED;
>>> +}
>>> +
>>> +#ifdef CONFIG_ARM64
>>> +static DEFINE_PER_CPU(struct timer_of, tegra_to) = {
>>> +	.flags = TIMER_OF_CLOCK | TIMER_OF_BASE,
>>> +
>>> +	.clkevt = {
>>> +		.name = "tegra_timer",
>>> +		.rating = 460,
>>> +		.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
>>> +		.set_next_event = tegra_timer_set_next_event,
>>> +		.set_state_shutdown = tegra_timer_shutdown,
>>> +		.set_state_periodic = tegra_timer_set_periodic,
>>> +		.set_state_oneshot = tegra_timer_shutdown,
>>> +		.tick_resume = tegra_timer_shutdown,
>>> +	},
>>> +};
>>> +
>>> +static int tegra_timer_setup(unsigned int cpu)
>>> +{
>>> +	struct timer_of *to = per_cpu_ptr(&tegra_to, cpu);
>>> +
>>> +	irq_force_affinity(to->clkevt.irq, cpumask_of(cpu));
>>> +	enable_irq(to->clkevt.irq);
>>> +
>>> +	clockevents_config_and_register(&to->clkevt, timer_of_rate(to),
>>> +					1, /* min */
>>> +					0x1fffffff); /* 29 bits */
>>>  
>>> -	timer_shutdown(evt);
>>> -	timer_writel(reg, TIMER3_BASE + TIMER_PTV);
>>>  	return 0;
>>>  }
>>>  
>>> -static struct clock_event_device tegra_clockevent = {
>>> -	.name			= "timer0",
>>> -	.rating			= 300,
>>> -	.features		= CLOCK_EVT_FEAT_ONESHOT |
>>> -				  CLOCK_EVT_FEAT_PERIODIC |
>>> -				  CLOCK_EVT_FEAT_DYNIRQ,
>>> -	.set_next_event		= tegra_timer_set_next_event,
>>> -	.set_state_shutdown	= tegra_timer_shutdown,
>>> -	.set_state_periodic	= tegra_timer_set_periodic,
>>> -	.set_state_oneshot	= tegra_timer_shutdown,
>>> -	.tick_resume		= tegra_timer_shutdown,
>>> +static int tegra_timer_stop(unsigned int cpu)
>>> +{
>>> +	struct timer_of *to = per_cpu_ptr(&tegra_to, cpu);
>>> +
>>> +	to->clkevt.set_state_shutdown(&to->clkevt);
>>> +	disable_irq_nosync(to->clkevt.irq);
>>> +
>>> +	return 0;
>>> +}
>>> +#else /* CONFIG_ARM */
>>> +static struct timer_of tegra_to = {
>>> +	.flags = TIMER_OF_CLOCK | TIMER_OF_BASE | TIMER_OF_IRQ,
>>> +
>>> +	.clkevt = {
>>> +		.name = "tegra_timer",
>>> +		.rating	= 300,
>>> +		.features = CLOCK_EVT_FEAT_ONESHOT |
>>> +			    CLOCK_EVT_FEAT_PERIODIC |
>>> +			    CLOCK_EVT_FEAT_DYNIRQ,
>>> +		.set_next_event	= tegra_timer_set_next_event,
>>> +		.set_state_shutdown = tegra_timer_shutdown,
>>> +		.set_state_periodic = tegra_timer_set_periodic,
>>> +		.set_state_oneshot = tegra_timer_shutdown,
>>> +		.tick_resume = tegra_timer_shutdown,
>>> +		.cpumask = cpu_possible_mask,
>>> +	},
>>> +
>>> +	.of_irq = {
>>> +		.index = 2,
>>> +		.flags = IRQF_TIMER | IRQF_TRIGGER_HIGH,
>>> +		.handler = tegra_timer_isr,
>>> +	},
>>>  };
>>>  
>>>  static u64 notrace tegra_read_sched_clock(void)
>>>  {
>>> -	return timer_readl(TIMERUS_CNTR_1US);
>>> +	return readl(timer_reg_base + TIMERUS_CNTR_1US);
>>> +}
>>> +
>>> +static unsigned long tegra_delay_timer_read_counter_long(void)
>>> +{
>>> +	return readl(timer_reg_base + TIMERUS_CNTR_1US);
>>>  }
>>>  
>>>  /*
>>> @@ -143,98 +223,188 @@ static void tegra_read_persistent_clock64(struct timespec64 *ts)
>>>  	timespec64_add_ns(&persistent_ts, delta * NSEC_PER_MSEC);
>>>  	*ts = persistent_ts;
>>>  }
>>> +#endif
>>>  
>>> -static unsigned long tegra_delay_timer_read_counter_long(void)
>>> +static int tegra_timer_suspend(void)
>>>  {
>>> -	return readl(timer_reg_base + TIMERUS_CNTR_1US);
>>> +#ifdef CONFIG_ARM64
>>> +	int cpu;
>>> +
>>> +	for_each_possible_cpu(cpu) {
>>> +		struct timer_of *to = per_cpu_ptr(&tegra_to, cpu);
>>> +		void __iomem *reg_base = timer_of_base(to);
>>> +
>>> +		writel(TIMER_PCR_INTR_CLR, reg_base + TIMER_PCR);
>>> +	}
>>> +#else
>>> +	void __iomem *reg_base = timer_of_base(&tegra_to);
>>> +
>>> +	writel(TIMER_PCR_INTR_CLR, reg_base + TIMER_PCR);
>>> +#endif
>>> +
>>> +	return 0;
>>>  }
>>>  
>>> -static irqreturn_t tegra_timer_interrupt(int irq, void *dev_id)
>>> +static void tegra_timer_resume(void)
>>>  {
>>> -	struct clock_event_device *evt = (struct clock_event_device *)dev_id;
>>> -	timer_writel(1<<30, TIMER3_BASE + TIMER_PCR);
>>> -	evt->event_handler(evt);
>>> -	return IRQ_HANDLED;
>>> +	writel(usec_config, timer_reg_base + TIMERUS_USEC_CFG);
>>>  }
>>>  
>>> -static struct irqaction tegra_timer_irq = {
>>> -	.name		= "timer0",
>>> -	.flags		= IRQF_TIMER | IRQF_TRIGGER_HIGH,
>>> -	.handler	= tegra_timer_interrupt,
>>> -	.dev_id		= &tegra_clockevent,
>>> +static struct syscore_ops tegra_timer_syscore_ops = {
>>> +	.suspend = tegra_timer_suspend,
>>> +	.resume = tegra_timer_resume,
>>>  };
>>>  
>>> -static int __init tegra20_init_timer(struct device_node *np)
>>> +static int tegra_timer_init(struct device_node *np, struct timer_of *to)
>>>  {
>>> -	struct clk *clk;
>>> -	unsigned long rate;
>>> -	int ret;
>>> +	int ret = 0;
>>>  
>>> -	timer_reg_base = of_iomap(np, 0);
>>> -	if (!timer_reg_base) {
>>> -		pr_err("Can't map timer registers\n");
>>> -		return -ENXIO;
>>> -	}
>>> +	ret = timer_of_init(np, to);
>>> +	if (ret < 0)
>>> +		goto out;
>>>  
>>> -	tegra_timer_irq.irq = irq_of_parse_and_map(np, 2);
>>> -	if (tegra_timer_irq.irq <= 0) {
>>> -		pr_err("Failed to map timer IRQ\n");
>>> -		return -EINVAL;
>>> -	}
>>> +	timer_reg_base = timer_of_base(to);
>>>  
>>> -	clk = of_clk_get(np, 0);
>>> -	if (IS_ERR(clk)) {
>>> -		pr_warn("Unable to get timer clock. Assuming 12Mhz input clock.\n");
>>> -		rate = 12000000;
>>> -	} else {
>>> -		clk_prepare_enable(clk);
>>> -		rate = clk_get_rate(clk);
>>> -	}
>>> -
>>> -	switch (rate) {
>>> +	/*
>>> +	 * Configure microsecond timers to have 1MHz clock
>>> +	 * Config register is 0xqqww, where qq is "dividend", ww is "divisor"
>>> +	 * Uses n+1 scheme
>>> +	 */
>>> +	switch (timer_of_rate(to)) {
>>>  	case 12000000:
>>> -		timer_writel(0x000b, TIMERUS_USEC_CFG);
>>> +		usec_config = 0x000b; /* (11+1)/(0+1) */
>>> +		break;
>>> +	case 12800000:
>>> +		usec_config = 0x043f; /* (63+1)/(4+1) */
>>>  		break;
>>>  	case 13000000:
>>> -		timer_writel(0x000c, TIMERUS_USEC_CFG);
>>> +		usec_config = 0x000c; /* (12+1)/(0+1) */
>>> +		break;
>>> +	case 16800000:
>>> +		usec_config = 0x0453; /* (83+1)/(4+1) */
>>>  		break;
>>>  	case 19200000:
>>> -		timer_writel(0x045f, TIMERUS_USEC_CFG);
>>> +		usec_config = 0x045f; /* (95+1)/(4+1) */
>>>  		break;
>>>  	case 26000000:
>>> -		timer_writel(0x0019, TIMERUS_USEC_CFG);
>>> +		usec_config = 0x0019; /* (25+1)/(0+1) */
>>> +		break;
>>> +	case 38400000:
>>> +		usec_config = 0x04bf; /* (191+1)/(4+1) */
>>> +		break;
>>> +	case 48000000:
>>> +		usec_config = 0x002f; /* (47+1)/(0+1) */
>>>  		break;
>>>  	default:
>>> -		WARN(1, "Unknown clock rate");
>>> +		ret = -EINVAL;
>>> +		goto out;
>>> +	}
>>> +
>>> +	writel(usec_config, timer_of_base(to) + TIMERUS_USEC_CFG);
>>> +
>>> +	register_syscore_ops(&tegra_timer_syscore_ops);
>>> +out:
>>> +	return ret;
>>> +}
>>> +
>>> +#ifdef CONFIG_ARM64
>>> +static int __init tegra210_timer_init(struct device_node *np)
>>> +{
>>> +	int cpu, ret = 0;
>>> +	struct timer_of *to;
>>> +
>>> +	to = this_cpu_ptr(&tegra_to);
>>> +	ret = tegra_timer_init(np, to);
>>> +	if (ret < 0)
>>> +		goto out;
>>> +
>>> +	for_each_possible_cpu(cpu) {
>>> +		struct timer_of *cpu_to;
>>> +
>>> +		cpu_to = per_cpu_ptr(&tegra_to, cpu);
>>> +		cpu_to->of_base.base = timer_reg_base + TIMER_FOR_CPU(cpu);
>>> +		cpu_to->of_clk.rate = timer_of_rate(to);
>>> +		cpu_to->clkevt.cpumask = cpumask_of(cpu);
>>> +
>>> +		cpu_to->clkevt.irq =
>>> +			irq_of_parse_and_map(np, IRQ_IDX_FOR_CPU(cpu));
>>> +		if (!cpu_to->clkevt.irq) {
>>> +			pr_err("%s: can't map IRQ for CPU%d\n",
>>> +			       __func__, cpu);
>>> +			ret = -EINVAL;
>>> +			goto out;
>>> +		}
>>> +
>>> +		irq_set_status_flags(cpu_to->clkevt.irq, IRQ_NOAUTOEN);
>>> +		ret = request_irq(cpu_to->clkevt.irq, tegra_timer_isr,
>>> +				  IRQF_TIMER | IRQF_NOBALANCING,
>>> +				  cpu_to->clkevt.name, &cpu_to->clkevt);
>>> +		if (ret) {
>>> +			pr_err("%s: cannot setup irq %d for CPU%d\n",
>>> +				__func__, cpu_to->clkevt.irq, cpu);
>>> +			ret = -EINVAL;
>>> +			goto out_irq;
>>> +		}
>>> +	}
>>> +
>>> +	cpuhp_setup_state(CPUHP_AP_TEGRA_TIMER_STARTING,
>>> +			  "AP_TEGRA_TIMER_STARTING", tegra_timer_setup,
>>> +			  tegra_timer_stop);
>>> +
>>> +	return ret;
>>> +
>>> +out_irq:
>>> +	for_each_possible_cpu(cpu) {
>>> +		struct timer_of *cpu_to;
>>> +
>>> +		cpu_to = per_cpu_ptr(&tegra_to, cpu);
>>> +		if (cpu_to->clkevt.irq) {
>>> +			free_irq(cpu_to->clkevt.irq, &cpu_to->clkevt);
>>> +			irq_dispose_mapping(cpu_to->clkevt.irq);
>>> +		}
>>>  	}
>>> +out:
>>> +	timer_of_cleanup(to);
>>> +	return ret;
>>> +}
>>> +TIMER_OF_DECLARE(tegra210_timer, "nvidia,tegra210-timer", tegra210_timer_init);
>>> +#else /* CONFIG_ARM */
>>> +static int __init tegra20_init_timer(struct device_node *np)
>>> +{
>> What about T132? Isn't it ARM64 which uses tegra20-timer IP? At least T132 DT suggests so and seems this change will break it.
>>
>> [snip]
>>
> 
> Ah, noticed the "depends on ARM" in Kconfig.. Seems okay then.
> 


This is a good point, because even though we had 'depends on ARM', this
still means that the Tegra132 DT is incorrect.

Joseph, can you take a quick look at Tegra132?

Cheers
Jon

-- 
nvpublic

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