diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/clocksource/timer-tegra.c | 416 |
1 files changed, 416 insertions, 0 deletions
diff --git a/drivers/clocksource/timer-tegra.c b/drivers/clocksource/timer-tegra.c new file mode 100644 index 000000000..e9635c25e --- /dev/null +++ b/drivers/clocksource/timer-tegra.c @@ -0,0 +1,416 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2010 Google, Inc. + * + * Author: + * Colin Cross <ccross@google.com> + */ + +#define pr_fmt(fmt) "tegra-timer: " fmt + +#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/interrupt.h> +#include <linux/of_address.h> +#include <linux/of_irq.h> +#include <linux/percpu.h> +#include <linux/sched_clock.h> +#include <linux/time.h> + +#include "timer-of.h" + +#define RTC_SECONDS 0x08 +#define RTC_SHADOW_SECONDS 0x0c +#define RTC_MILLISECONDS 0x10 + +#define TIMERUS_CNTR_1US 0x10 +#define TIMERUS_USEC_CFG 0x14 +#define TIMERUS_CNTR_FREEZE 0x4c + +#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) + +#define TIMER1_BASE 0x00 +#define TIMER2_BASE 0x08 +#define TIMER3_BASE 0x50 +#define TIMER4_BASE 0x58 +#define TIMER10_BASE 0x90 + +#define TIMER1_IRQ_IDX 0 +#define TIMER10_IRQ_IDX 10 + +#define TIMER_1MHz 1000000 + +static u32 usec_config; +static void __iomem *timer_reg_base; + +static int tegra_timer_set_next_event(unsigned long cycles, + struct clock_event_device *evt) +{ + void __iomem *reg_base = timer_of_base(to_timer_of(evt)); + + /* + * Tegra's timer uses n+1 scheme for the counter, i.e. timer will + * fire after one tick if 0 is loaded. + * + * The minimum and maximum numbers of oneshot ticks are defined + * by clockevents_config_and_register(1, 0x1fffffff + 1) invocation + * below in the code. Hence the cycles (ticks) can't be outside of + * a range supportable by hardware. + */ + writel_relaxed(TIMER_PTV_EN | (cycles - 1), reg_base + TIMER_PTV); + + return 0; +} + +static int tegra_timer_shutdown(struct clock_event_device *evt) +{ + void __iomem *reg_base = timer_of_base(to_timer_of(evt)); + + writel_relaxed(0, reg_base + TIMER_PTV); + + return 0; +} + +static int tegra_timer_set_periodic(struct clock_event_device *evt) +{ + void __iomem *reg_base = timer_of_base(to_timer_of(evt)); + unsigned long period = timer_of_period(to_timer_of(evt)); + + writel_relaxed(TIMER_PTV_EN | TIMER_PTV_PER | (period - 1), + reg_base + TIMER_PTV); + + return 0; +} + +static irqreturn_t tegra_timer_isr(int irq, void *dev_id) +{ + struct clock_event_device *evt = dev_id; + void __iomem *reg_base = timer_of_base(to_timer_of(evt)); + + writel_relaxed(TIMER_PCR_INTR_CLR, reg_base + TIMER_PCR); + evt->event_handler(evt); + + return IRQ_HANDLED; +} + +static void tegra_timer_suspend(struct clock_event_device *evt) +{ + void __iomem *reg_base = timer_of_base(to_timer_of(evt)); + + writel_relaxed(TIMER_PCR_INTR_CLR, reg_base + TIMER_PCR); +} + +static void tegra_timer_resume(struct clock_event_device *evt) +{ + writel_relaxed(usec_config, timer_reg_base + TIMERUS_USEC_CFG); +} + +static DEFINE_PER_CPU(struct timer_of, tegra_to) = { + .flags = TIMER_OF_CLOCK | TIMER_OF_BASE, + + .clkevt = { + .name = "tegra_timer", + .features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC, + .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, + .suspend = tegra_timer_suspend, + .resume = tegra_timer_resume, + }, +}; + +static int tegra_timer_setup(unsigned int cpu) +{ + struct timer_of *to = per_cpu_ptr(&tegra_to, cpu); + + writel_relaxed(0, timer_of_base(to) + TIMER_PTV); + writel_relaxed(TIMER_PCR_INTR_CLR, timer_of_base(to) + TIMER_PCR); + + irq_force_affinity(to->clkevt.irq, cpumask_of(cpu)); + enable_irq(to->clkevt.irq); + + /* + * Tegra's timer uses n+1 scheme for the counter, i.e. timer will + * fire after one tick if 0 is loaded and thus minimum number of + * ticks is 1. In result both of the clocksource's tick limits are + * higher than a minimum and maximum that hardware register can + * take by 1, this is then taken into account by set_next_event + * callback. + */ + clockevents_config_and_register(&to->clkevt, timer_of_rate(to), + 1, /* min */ + 0x1fffffff + 1); /* max 29 bits + 1 */ + + return 0; +} + +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; +} + +static u64 notrace tegra_read_sched_clock(void) +{ + return readl_relaxed(timer_reg_base + TIMERUS_CNTR_1US); +} + +#ifdef CONFIG_ARM +static unsigned long tegra_delay_timer_read_counter_long(void) +{ + return readl_relaxed(timer_reg_base + TIMERUS_CNTR_1US); +} + +static struct delay_timer tegra_delay_timer = { + .read_current_timer = tegra_delay_timer_read_counter_long, + .freq = TIMER_1MHz, +}; +#endif + +static struct timer_of suspend_rtc_to = { + .flags = TIMER_OF_BASE | TIMER_OF_CLOCK, +}; + +/* + * tegra_rtc_read - Reads the Tegra RTC registers + * Care must be taken that this function is not called while the + * tegra_rtc driver could be executing to avoid race conditions + * on the RTC shadow register + */ +static u64 tegra_rtc_read_ms(struct clocksource *cs) +{ + void __iomem *reg_base = timer_of_base(&suspend_rtc_to); + + u32 ms = readl_relaxed(reg_base + RTC_MILLISECONDS); + u32 s = readl_relaxed(reg_base + RTC_SHADOW_SECONDS); + + return (u64)s * MSEC_PER_SEC + ms; +} + +static struct clocksource suspend_rtc_clocksource = { + .name = "tegra_suspend_timer", + .rating = 200, + .read = tegra_rtc_read_ms, + .mask = CLOCKSOURCE_MASK(32), + .flags = CLOCK_SOURCE_IS_CONTINUOUS | CLOCK_SOURCE_SUSPEND_NONSTOP, +}; + +static inline unsigned int tegra_base_for_cpu(int cpu, bool tegra20) +{ + if (tegra20) { + switch (cpu) { + case 0: + return TIMER1_BASE; + case 1: + return TIMER2_BASE; + case 2: + return TIMER3_BASE; + default: + return TIMER4_BASE; + } + } + + return TIMER10_BASE + cpu * 8; +} + +static inline unsigned int tegra_irq_idx_for_cpu(int cpu, bool tegra20) +{ + if (tegra20) + return TIMER1_IRQ_IDX + cpu; + + return TIMER10_IRQ_IDX + cpu; +} + +static inline unsigned long tegra_rate_for_timer(struct timer_of *to, + bool tegra20) +{ + /* + * TIMER1-9 are fixed to 1MHz, TIMER10-13 are running off the + * parent clock. + */ + if (tegra20) + return TIMER_1MHz; + + return timer_of_rate(to); +} + +static int __init tegra_init_timer(struct device_node *np, bool tegra20, + int rating) +{ + struct timer_of *to; + int cpu, ret; + + to = this_cpu_ptr(&tegra_to); + ret = timer_of_init(np, to); + if (ret) + goto out; + + timer_reg_base = timer_of_base(to); + + /* + * 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: + usec_config = 0x000b; /* (11+1)/(0+1) */ + break; + case 12800000: + usec_config = 0x043f; /* (63+1)/(4+1) */ + break; + case 13000000: + usec_config = 0x000c; /* (12+1)/(0+1) */ + break; + case 16800000: + usec_config = 0x0453; /* (83+1)/(4+1) */ + break; + case 19200000: + usec_config = 0x045f; /* (95+1)/(4+1) */ + break; + case 26000000: + 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: + ret = -EINVAL; + goto out; + } + + writel_relaxed(usec_config, timer_reg_base + TIMERUS_USEC_CFG); + + for_each_possible_cpu(cpu) { + struct timer_of *cpu_to = per_cpu_ptr(&tegra_to, cpu); + unsigned long flags = IRQF_TIMER | IRQF_NOBALANCING; + unsigned long rate = tegra_rate_for_timer(to, tegra20); + unsigned int base = tegra_base_for_cpu(cpu, tegra20); + unsigned int idx = tegra_irq_idx_for_cpu(cpu, tegra20); + unsigned int irq = irq_of_parse_and_map(np, idx); + + if (!irq) { + pr_err("failed to map irq for cpu%d\n", cpu); + ret = -EINVAL; + goto out_irq; + } + + cpu_to->clkevt.irq = irq; + cpu_to->clkevt.rating = rating; + cpu_to->clkevt.cpumask = cpumask_of(cpu); + cpu_to->of_base.base = timer_reg_base + base; + cpu_to->of_clk.period = rate / HZ; + cpu_to->of_clk.rate = rate; + + irq_set_status_flags(cpu_to->clkevt.irq, IRQ_NOAUTOEN); + + ret = request_irq(cpu_to->clkevt.irq, tegra_timer_isr, flags, + cpu_to->clkevt.name, &cpu_to->clkevt); + if (ret) { + pr_err("failed to set up irq for cpu%d: %d\n", + cpu, ret); + irq_dispose_mapping(cpu_to->clkevt.irq); + cpu_to->clkevt.irq = 0; + goto out_irq; + } + } + + sched_clock_register(tegra_read_sched_clock, 32, TIMER_1MHz); + + ret = clocksource_mmio_init(timer_reg_base + TIMERUS_CNTR_1US, + "timer_us", TIMER_1MHz, 300, 32, + clocksource_mmio_readl_up); + if (ret) + pr_err("failed to register clocksource: %d\n", ret); + +#ifdef CONFIG_ARM + register_current_timer_delay(&tegra_delay_timer); +#endif + + ret = cpuhp_setup_state(CPUHP_AP_TEGRA_TIMER_STARTING, + "AP_TEGRA_TIMER_STARTING", tegra_timer_setup, + tegra_timer_stop); + if (ret) + pr_err("failed to set up cpu hp state: %d\n", ret); + + 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); + } + } + + to->of_base.base = timer_reg_base; +out: + timer_of_cleanup(to); + + return ret; +} + +static int __init tegra210_init_timer(struct device_node *np) +{ + /* + * Arch-timer can't survive across power cycle of CPU core and + * after CPUPORESET signal due to a system design shortcoming, + * hence tegra-timer is more preferable on Tegra210. + */ + return tegra_init_timer(np, false, 460); +} +TIMER_OF_DECLARE(tegra210_timer, "nvidia,tegra210-timer", tegra210_init_timer); + +static int __init tegra20_init_timer(struct device_node *np) +{ + int rating; + + /* + * Tegra20 and Tegra30 have Cortex A9 CPU that has a TWD timer, + * that timer runs off the CPU clock and hence is subjected to + * a jitter caused by DVFS clock rate changes. Tegra-timer is + * more preferable for older Tegra's, while later SoC generations + * have arch-timer as a main per-CPU timer and it is not affected + * by DVFS changes. + */ + if (of_machine_is_compatible("nvidia,tegra20") || + of_machine_is_compatible("nvidia,tegra30")) + rating = 460; + else + rating = 330; + + return tegra_init_timer(np, true, rating); +} +TIMER_OF_DECLARE(tegra20_timer, "nvidia,tegra20-timer", tegra20_init_timer); + +static int __init tegra20_init_rtc(struct device_node *np) +{ + int ret; + + ret = timer_of_init(np, &suspend_rtc_to); + if (ret) + return ret; + + return clocksource_register_hz(&suspend_rtc_clocksource, 1000); +} +TIMER_OF_DECLARE(tegra20_rtc, "nvidia,tegra20-rtc", tegra20_init_rtc); |