Re: [PATCH 09/17] clocksource/timer-riscv: New RISC-V Clocksource

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



CC clocksource folks

On Wed, Jun 7, 2017 at 12:59 AM, Palmer Dabbelt <palmer@xxxxxxxxxxx> wrote:
> The RISC-V ISA defines a single RTC as well as an SBI oneshot timer.
> This timer is present on all RISC-V systems.
>
> Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxx>
> ---
>  drivers/clocksource/Kconfig       |   8 +++
>  drivers/clocksource/Makefile      |   1 +
>  drivers/clocksource/timer-riscv.c | 118 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 127 insertions(+)
>  create mode 100644 drivers/clocksource/timer-riscv.c
>
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index 545d541ae20e..1c2c6e7c7fab 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -612,4 +612,12 @@ config CLKSRC_ST_LPC
>           Enable this option to use the Low Power controller timer
>           as clocksource.
>
> +config CLKSRC_RISCV
> +       #bool "Clocksource for the RISC-V platform"
> +       def_bool y if RISCV
> +       depends on RISCV
> +       help
> +         This enables a clocksource based on the RISC-V SBI timer, which is
> +         built in to all RISC-V systems.
> +
>  endmenu
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index 2b5b56a6f00f..408ed9d314dc 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -73,3 +73,4 @@ obj-$(CONFIG_H8300_TMR16)             += h8300_timer16.o
>  obj-$(CONFIG_H8300_TPU)                        += h8300_tpu.o
>  obj-$(CONFIG_CLKSRC_ST_LPC)            += clksrc_st_lpc.o
>  obj-$(CONFIG_X86_NUMACHIP)             += numachip.o
> +obj-$(CONFIG_CLKSRC_RISCV)             += timer-riscv.o
> diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c
> new file mode 100644
> index 000000000000..04ef7b9130b3
> --- /dev/null
> +++ b/drivers/clocksource/timer-riscv.c
> @@ -0,0 +1,118 @@
> +/*
> + * Copyright (C) 2012 Regents of the University of California
> + * Copyright (C) 2017 SiFive
> + *
> + *   This program is free software; you can redistribute it and/or
> + *   modify it under the terms of the GNU General Public License
> + *   as published by the Free Software Foundation, version 2.
> + *
> + *   This program is distributed in the hope that it will be useful,
> + *   but WITHOUT ANY WARRANTY; without even the implied warranty of
> + *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + *   GNU General Public License for more details.
> + */
> +
> +#include <linux/clocksource.h>
> +#include <linux/clockchips.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/delay.h>
> +#include <linux/of.h>
> +
> +#include <asm/irq.h>
> +#include <asm/csr.h>
> +#include <asm/sbi.h>
> +#include <asm/delay.h>
> +
> +unsigned long riscv_timebase;
> +
> +static DEFINE_PER_CPU(struct clock_event_device, clock_event);
> +
> +static int riscv_timer_set_next_event(unsigned long delta,
> +       struct clock_event_device *evdev)
> +{
> +       sbi_set_timer(get_cycles() + delta);
> +       return 0;
> +}
> +
> +static int riscv_timer_set_oneshot(struct clock_event_device *evt)
> +{
> +       /* no-op; only one mode */
> +       return 0;
> +}
> +
> +static int riscv_timer_set_shutdown(struct clock_event_device *evt)
> +{
> +       /* can't stop the clock! */
> +       return 0;
> +}
> +
> +static u64 riscv_rdtime(struct clocksource *cs)
> +{
> +       return get_cycles();
> +}
> +
> +static struct clocksource riscv_clocksource = {
> +       .name = "riscv_clocksource",
> +       .rating = 300,
> +       .read = riscv_rdtime,
> +#ifdef CONFIG_64BITS
> +       .mask = CLOCKSOURCE_MASK(64),
> +#else
> +       .mask = CLOCKSOURCE_MASK(32),
> +#endif /* CONFIG_64BITS */
> +       .flags = CLOCK_SOURCE_IS_CONTINUOUS,
> +};
> +
> +void riscv_timer_interrupt(void)
> +{
> +       int cpu = smp_processor_id();
> +       struct clock_event_device *evdev = &per_cpu(clock_event, cpu);
> +
> +       evdev->event_handler(evdev);
> +}
> +
> +void __init init_clockevent(void)
> +{
> +       int cpu = smp_processor_id();
> +       struct clock_event_device *ce = &per_cpu(clock_event, cpu);
> +
> +       *ce = (struct clock_event_device){
> +               .name = "riscv_timer_clockevent",
> +               .features = CLOCK_EVT_FEAT_ONESHOT,
> +               .rating = 300,
> +               .cpumask = cpumask_of(cpu),
> +               .set_next_event = riscv_timer_set_next_event,
> +               .set_state_oneshot  = riscv_timer_set_oneshot,
> +               .set_state_shutdown = riscv_timer_set_shutdown,
> +       };
> +
> +       /* Enable timer interrupts */
> +       csr_set(sie, SIE_STIE);
> +
> +       clockevents_config_and_register(ce, riscv_timebase, 100, 0x7fffffff);
> +}
> +
> +static unsigned long __init of_timebase(void)
> +{
> +       struct device_node *cpu;
> +       const __be32 *prop;
> +
> +       cpu = of_find_node_by_path("/cpus");
> +       if (cpu) {
> +               prop = of_get_property(cpu, "timebase-frequency", NULL);
> +               if (prop)
> +                       return be32_to_cpu(*prop);
> +       }
> +
> +       return 10000000;
> +}
> +
> +void __init time_init(void)
> +{
> +       riscv_timebase = of_timebase();
> +       lpj_fine = riscv_timebase / HZ;
> +
> +       clocksource_register_hz(&riscv_clocksource, riscv_timebase);
> +       init_clockevent();
> +}
> --
> 2.13.0



[Index of Archives]     [Linux Kernel]     [Kernel Newbies]     [x86 Platform Driver]     [Netdev]     [Linux Wireless]     [Netfilter]     [Bugtraq]     [Linux Filesystems]     [Yosemite Discussion]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Device Mapper]

  Powered by Linux