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Subject: Re: [PATCH V5 2/7] clocksource: tegra: add Tegra210 timer support
From:   Dmitry Osipenko <digetx@gmail.com>
To:     Joseph Lo <josephl@nvidia.com>,
        Thierry Reding <thierry.reding@gmail.com>,
        Jonathan Hunter <jonathanh@nvidia.com>,
        Daniel Lezcano <daniel.lezcano@linaro.org>,
        Thomas Gleixner <tglx@linutronix.de>
Cc:     linux-tegra@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-kernel@vger.kernel.org, Thierry Reding <treding@nvidia.com>
References: <20190201033621.16814-1-josephl@nvidia.com>
 <20190201033621.16814-3-josephl@nvidia.com>
 <9370a0e4-2c76-6e9e-9219-121f92cdb14a@gmail.com>
Message-ID: <46a1a62f-29b1-caac-ba68-e1394a76b3af@gmail.com>
Date:   Fri, 1 Feb 2019 16:11:02 +0300
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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@linaro.org>
>> Cc: Thomas Gleixner <tglx@linutronix.de>
>> Cc: linux-kernel@vger.kernel.org
>> Signed-off-by: Joseph Lo <josephl@nvidia.com>
>> Acked-by: Thierry Reding <treding@nvidia.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.