Date:   Wed, 13 Feb 2019 09:55:33 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Joseph Lo <josephl@...dia.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        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 V6 2/7] clocksource: tegra: add Tegra210 timer support

On 08/02/2019 14:23, Joseph Lo wrote:
> Hi Daniel & Thomas,
> 
> Do we have the chance to get this patch merged for K5.1?

Hi Jospeh,

sorry for the delay, I was overbooked these past two weeks.

Overall it looks ok but give me a couple of days to review the driver
more deeply.


> On 2/2/19 12:16 AM, Joseph Lo wrote:
>> 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>
>> Acked-by: Jon Hunter <jonathanh@...dia.com>
>> ---
>> v6:
>>   * refine the timer defines
>>   * add ack tag from Jon.
>> 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 | 371 ++++++++++++++++++++--------
>>   include/linux/cpuhotplug.h          |   1 +
>>   3 files changed, 270 insertions(+), 104 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..f66edd63d7f4 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
>> @@ -39,74 +42,145 @@
>>   #define TIMERUS_USEC_CFG 0x14
>>   #define TIMERUS_CNTR_FREEZE 0x4c
>>   -#define TIMER1_BASE 0x0
>> -#define TIMER2_BASE 0x8
>> -#define TIMER3_BASE 0x50
>> -#define TIMER4_BASE 0x58
>> -
>> -#define TIMER_PTV 0x0
>> -#define TIMER_PCR 0x4
>> -
>> +#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_CPU0        0x50 /* TIMER3 */
>> +#else
>> +#define TIMER_CPU0        0x90 /* TIMER10 */
>> +#define TIMER10_IRQ_IDX        10
>> +#define IRQ_IDX_FOR_CPU(cpu)    (TIMER10_IRQ_IDX + cpu)
>> +#endif
>> +#define TIMER_BASE_FOR_CPU(cpu) (TIMER_CPU0 + (cpu) * 8)
>> +
>> +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 +217,188 @@ 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_BASE_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)
>> +{
>> +    int ret = 0;
>> +
>> +    ret = tegra_timer_init(np, &tegra_to);
>> +    if (ret < 0)
>> +        goto out;
>>   -    sched_clock_register(tegra_read_sched_clock, 32, 1000000);
>> +    tegra_to.of_base.base = timer_reg_base + TIMER_BASE_FOR_CPU(0);
>> +    tegra_to.of_clk.rate = 1000000; /* microsecond timer */
>>   +    sched_clock_register(tegra_read_sched_clock, 32,
>> +                 timer_of_rate(&tegra_to));
>>       ret = clocksource_mmio_init(timer_reg_base + TIMERUS_CNTR_1US,
>> -                    "timer_us", 1000000, 300, 32,
>> -                    clocksource_mmio_readl_up);
>> +                    "timer_us", timer_of_rate(&tegra_to),
>> +                    300, 32, clocksource_mmio_readl_up);
>>       if (ret) {
>>           pr_err("Failed to register clocksource\n");
>> -        return ret;
>> +        goto out;
>>       }
>>         tegra_delay_timer.read_current_timer =
>>               tegra_delay_timer_read_counter_long;
>> -    tegra_delay_timer.freq = 1000000;
>> +    tegra_delay_timer.freq = timer_of_rate(&tegra_to);
>>       register_current_timer_delay(&tegra_delay_timer);
>>   -    ret = setup_irq(tegra_timer_irq.irq, &tegra_timer_irq);
>> -    if (ret) {
>> -        pr_err("Failed to register timer IRQ: %d\n", ret);
>> -        return ret;
>> -    }
>> +    clockevents_config_and_register(&tegra_to.clkevt,
>> +                    timer_of_rate(&tegra_to),
>> +                    0x1,
>> +                    0x1fffffff);
>>   -    tegra_clockevent.cpumask = cpu_possible_mask;
>> -    tegra_clockevent.irq = tegra_timer_irq.irq;
>> -    clockevents_config_and_register(&tegra_clockevent, 1000000,
>> -                    0x1, 0x1fffffff);
>> +    return ret;
>> +out:
>> +    timer_of_cleanup(&tegra_to);
>>   -    return 0;
>> +    return ret;
>>   }
>>   TIMER_OF_DECLARE(tegra20_timer, "nvidia,tegra20-timer",
>> tegra20_init_timer);
>>   @@ -261,3 +425,4 @@ static int __init tegra20_init_rtc(struct
>> device_node *np)
>>       return register_persistent_clock(tegra_read_persistent_clock64);
>>   }
>>   TIMER_OF_DECLARE(tegra20_rtc, "nvidia,tegra20-rtc", tegra20_init_rtc);
>> +#endif
>> diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
>> index fd586d0301e7..e78281d07b70 100644
>> --- a/include/linux/cpuhotplug.h
>> +++ b/include/linux/cpuhotplug.h
>> @@ -121,6 +121,7 @@ enum cpuhp_state {
>>       CPUHP_AP_EXYNOS4_MCT_TIMER_STARTING,
>>       CPUHP_AP_ARM_TWD_STARTING,
>>       CPUHP_AP_QCOM_TIMER_STARTING,
>> +    CPUHP_AP_TEGRA_TIMER_STARTING,
>>       CPUHP_AP_ARMADA_TIMER_STARTING,
>>       CPUHP_AP_MARCO_TIMER_STARTING,
>>       CPUHP_AP_MIPS_GIC_TIMER_STARTING,
>>


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