diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/clocksource/Kconfig | 10 | ||||
| -rw-r--r-- | drivers/clocksource/Makefile | 1 | ||||
| -rw-r--r-- | drivers/clocksource/jcore-pit.c | 249 |
3 files changed, 260 insertions, 0 deletions
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index 245190839359..e2c6e43cf8ca 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -417,6 +417,16 @@ config SYS_SUPPORTS_SH_TMU config SYS_SUPPORTS_EM_STI bool +config CLKSRC_JCORE_PIT + bool "J-Core PIT timer driver" if COMPILE_TEST + depends on OF + depends on GENERIC_CLOCKEVENTS + depends on HAS_IOMEM + select CLKSRC_MMIO + help + This enables build of clocksource and clockevent driver for + the integrated PIT in the J-Core synthesizable, open source SoC. + config SH_TIMER_CMT bool "Renesas CMT timer driver" if COMPILE_TEST depends on GENERIC_CLOCKEVENTS diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile index fd9d6df0bbc0..cf87f407f1ad 100644 --- a/drivers/clocksource/Makefile +++ b/drivers/clocksource/Makefile @@ -5,6 +5,7 @@ obj-$(CONFIG_ATMEL_TCB_CLKSRC) += tcb_clksrc.o obj-$(CONFIG_X86_PM_TIMER) += acpi_pm.o obj-$(CONFIG_SCx200HR_TIMER) += scx200_hrt.o obj-$(CONFIG_CS5535_CLOCK_EVENT_SRC) += cs5535-clockevt.o +obj-$(CONFIG_CLKSRC_JCORE_PIT) += jcore-pit.o obj-$(CONFIG_SH_TIMER_CMT) += sh_cmt.o obj-$(CONFIG_SH_TIMER_MTU2) += sh_mtu2.o obj-$(CONFIG_SH_TIMER_TMU) += sh_tmu.o diff --git a/drivers/clocksource/jcore-pit.c b/drivers/clocksource/jcore-pit.c new file mode 100644 index 000000000000..54e1665aa03c --- /dev/null +++ b/drivers/clocksource/jcore-pit.c @@ -0,0 +1,249 @@ +/* + * J-Core SoC PIT/clocksource driver + * + * Copyright (C) 2015-2016 Smart Energy Instruments, Inc. + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + */ + +#include <linux/kernel.h> +#include <linux/slab.h> +#include <linux/interrupt.h> +#include <linux/clockchips.h> +#include <linux/clocksource.h> +#include <linux/sched_clock.h> +#include <linux/cpu.h> +#include <linux/cpuhotplug.h> +#include <linux/of_address.h> +#include <linux/of_irq.h> + +#define PIT_IRQ_SHIFT 12 +#define PIT_PRIO_SHIFT 20 +#define PIT_ENABLE_SHIFT 26 +#define PIT_PRIO_MASK 0xf + +#define REG_PITEN 0x00 +#define REG_THROT 0x10 +#define REG_COUNT 0x14 +#define REG_BUSPD 0x18 +#define REG_SECHI 0x20 +#define REG_SECLO 0x24 +#define REG_NSEC 0x28 + +struct jcore_pit { + struct clock_event_device ced; + void __iomem *base; + unsigned long periodic_delta; + u32 enable_val; +}; + +static void __iomem *jcore_pit_base; +static struct jcore_pit __percpu *jcore_pit_percpu; + +static notrace u64 jcore_sched_clock_read(void) +{ + u32 seclo, nsec, seclo0; + __iomem void *base = jcore_pit_base; + + seclo = readl(base + REG_SECLO); + do { + seclo0 = seclo; + nsec = readl(base + REG_NSEC); + seclo = readl(base + REG_SECLO); + } while (seclo0 != seclo); + + return seclo * NSEC_PER_SEC + nsec; +} + +static cycle_t jcore_clocksource_read(struct clocksource *cs) +{ + return jcore_sched_clock_read(); +} + +static int jcore_pit_disable(struct jcore_pit *pit) +{ + writel(0, pit->base + REG_PITEN); + return 0; +} + +static int jcore_pit_set(unsigned long delta, struct jcore_pit *pit) +{ + jcore_pit_disable(pit); + writel(delta, pit->base + REG_THROT); + writel(pit->enable_val, pit->base + REG_PITEN); + return 0; +} + +static int jcore_pit_set_state_shutdown(struct clock_event_device *ced) +{ + struct jcore_pit *pit = container_of(ced, struct jcore_pit, ced); + + return jcore_pit_disable(pit); +} + +static int jcore_pit_set_state_oneshot(struct clock_event_device *ced) +{ + struct jcore_pit *pit = container_of(ced, struct jcore_pit, ced); + + return jcore_pit_disable(pit); +} + +static int jcore_pit_set_state_periodic(struct clock_event_device *ced) +{ + struct jcore_pit *pit = container_of(ced, struct jcore_pit, ced); + + return jcore_pit_set(pit->periodic_delta, pit); +} + +static int jcore_pit_set_next_event(unsigned long delta, + struct clock_event_device *ced) +{ + struct jcore_pit *pit = container_of(ced, struct jcore_pit, ced); + + return jcore_pit_set(delta, pit); +} + +static int jcore_pit_local_init(unsigned cpu) +{ + struct jcore_pit *pit = this_cpu_ptr(jcore_pit_percpu); + unsigned buspd, freq; + + pr_info("Local J-Core PIT init on cpu %u\n", cpu); + + buspd = readl(pit->base + REG_BUSPD); + freq = DIV_ROUND_CLOSEST(NSEC_PER_SEC, buspd); + pit->periodic_delta = DIV_ROUND_CLOSEST(NSEC_PER_SEC, HZ * buspd); + + clockevents_config_and_register(&pit->ced, freq, 1, ULONG_MAX); + + return 0; +} + +static irqreturn_t jcore_timer_interrupt(int irq, void *dev_id) +{ + struct jcore_pit *pit = this_cpu_ptr(dev_id); + + if (clockevent_state_oneshot(&pit->ced)) + jcore_pit_disable(pit); + + pit->ced.event_handler(&pit->ced); + + return IRQ_HANDLED; +} + +static int __init jcore_pit_init(struct device_node *node) +{ + int err; + unsigned pit_irq, cpu; + unsigned long hwirq; + u32 irqprio, enable_val; + + jcore_pit_base = of_iomap(node, 0); + if (!jcore_pit_base) { + pr_err("Error: Cannot map base address for J-Core PIT\n"); + return -ENXIO; + } + + pit_irq = irq_of_parse_and_map(node, 0); + if (!pit_irq) { + pr_err("Error: J-Core PIT has no IRQ\n"); + return -ENXIO; + } + + pr_info("Initializing J-Core PIT at %p IRQ %d\n", + jcore_pit_base, pit_irq); + + err = clocksource_mmio_init(jcore_pit_base, "jcore_pit_cs", + NSEC_PER_SEC, 400, 32, + jcore_clocksource_read); + if (err) { + pr_err("Error registering clocksource device: %d\n", err); + return err; + } + + sched_clock_register(jcore_sched_clock_read, 32, NSEC_PER_SEC); + + jcore_pit_percpu = alloc_percpu(struct jcore_pit); + if (!jcore_pit_percpu) { + pr_err("Failed to allocate memory for clock event device\n"); + return -ENOMEM; + } + + err = request_irq(pit_irq, jcore_timer_interrupt, + IRQF_TIMER | IRQF_PERCPU, + "jcore_pit", jcore_pit_percpu); + if (err) { + pr_err("pit irq request failed: %d\n", err); + free_percpu(jcore_pit_percpu); + return err; + } + + /* + * The J-Core PIT is not hard-wired to a particular IRQ, but + * integrated with the interrupt controller such that the IRQ it + * generates is programmable, as follows: + * + * The bit layout of the PIT enable register is: + * + * .....e..ppppiiiiiiii............ + * + * where the .'s indicate unrelated/unused bits, e is enable, + * p is priority, and i is hard irq number. + * + * For the PIT included in AIC1 (obsolete but still in use), + * any hard irq (trap number) can be programmed via the 8 + * iiiiiiii bits, and a priority (0-15) is programmable + * separately in the pppp bits. + * + * For the PIT included in AIC2 (current), the programming + * interface is equivalent modulo interrupt mapping. This is + * why a different compatible tag was not used. However only + * traps 64-127 (the ones actually intended to be used for + * interrupts, rather than syscalls/exceptions/etc.) can be + * programmed (the high 2 bits of i are ignored) and the + * priority pppp is <<2'd and or'd onto the irq number. This + * choice seems to have been made on the hardware engineering + * side under an assumption that preserving old AIC1 priority + * mappings was important. Future models will likely ignore + * the pppp field. + */ + hwirq = irq_get_irq_data(pit_irq)->hwirq; + irqprio = (hwirq >> 2) & PIT_PRIO_MASK; + enable_val = (1U << PIT_ENABLE_SHIFT) + | (hwirq << PIT_IRQ_SHIFT) + | (irqprio << PIT_PRIO_SHIFT); + + for_each_present_cpu(cpu) { + struct jcore_pit *pit = per_cpu_ptr(jcore_pit_percpu, cpu); + + pit->base = of_iomap(node, cpu); + if (!pit->base) { + pr_err("Unable to map PIT for cpu %u\n", cpu); + continue; + } + + pit->ced.name = "jcore_pit"; + pit->ced.features = CLOCK_EVT_FEAT_PERIODIC + | CLOCK_EVT_FEAT_ONESHOT + | CLOCK_EVT_FEAT_PERCPU; + pit->ced.cpumask = cpumask_of(cpu); + pit->ced.rating = 400; + pit->ced.irq = pit_irq; + pit->ced.set_state_shutdown = jcore_pit_set_state_shutdown; + pit->ced.set_state_periodic = jcore_pit_set_state_periodic; + pit->ced.set_state_oneshot = jcore_pit_set_state_oneshot; + pit->ced.set_next_event = jcore_pit_set_next_event; + + pit->enable_val = enable_val; + } + + cpuhp_setup_state(CPUHP_AP_JCORE_TIMER_STARTING, + "AP_JCORE_TIMER_STARTING", + jcore_pit_local_init, NULL); + + return 0; +} + +CLOCKSOURCE_OF_DECLARE(jcore_pit, "jcore,pit", jcore_pit_init); |