Re: [PATCH v6 3/4] RISC-V: Remove CLINT related code from timer and arch

[Anup Patel <anup@brainfault.org>]

On Sat, Jul 25, 2020 at 10:46 AM Atish Patra <atishp@atishpatra.org> wrote:
>
> On Fri, Jul 24, 2020 at 12:19 AM Anup Patel <anup.patel@wdc.com> wrote:
> >
> > Right now the RISC-V timer driver is convoluted to support:
> > 1. Linux RISC-V S-mode (with MMU) where it will use TIME CSR for
> >    clocksource and SBI timer calls for clockevent device.
> > 2. Linux RISC-V M-mode (without MMU) where it will use CLINT MMIO
> >    counter register for clocksource and CLINT MMIO compare register
> >    for clockevent device.
> >
> > We now have a separate CLINT timer driver which also provide CLINT
> > based IPI operations so let's remove CLINT MMIO related code from
> > arch/riscv directory and RISC-V timer driver.
> >
> > Signed-off-by: Anup Patel <anup.patel@wdc.com>
> > Tested-by: Emil Renner Berhing <kernel@esmil.dk>
> > Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
> > ---
> >  arch/riscv/Kconfig                      |  2 +-
> >  arch/riscv/Kconfig.socs                 |  2 +
> >  arch/riscv/configs/nommu_virt_defconfig |  7 +--
> >  arch/riscv/include/asm/clint.h          | 14 ------
> >  arch/riscv/include/asm/timex.h          | 28 +++--------
> >  arch/riscv/kernel/Makefile              |  2 +-
> >  arch/riscv/kernel/clint.c               | 63 -------------------------
> >  arch/riscv/kernel/setup.c               |  2 -
> >  arch/riscv/kernel/smp.c                 |  1 -
> >  arch/riscv/kernel/smpboot.c             |  1 -
> >  drivers/clocksource/Kconfig             |  3 +-
> >  drivers/clocksource/timer-riscv.c       | 17 +------
> >  12 files changed, 16 insertions(+), 126 deletions(-)
> >  delete mode 100644 arch/riscv/include/asm/clint.h
> >  delete mode 100644 arch/riscv/kernel/clint.c
> >
> > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> > index fedb4a72b29a..57a72ae23d10 100644
> > --- a/arch/riscv/Kconfig
> > +++ b/arch/riscv/Kconfig
> > @@ -74,7 +74,7 @@ config RISCV
> >         select PCI_DOMAINS_GENERIC if PCI
> >         select PCI_MSI if PCI
> >         select RISCV_INTC
> > -       select RISCV_TIMER
> > +       select RISCV_TIMER if RISCV_SBI
> >         select SPARSEMEM_STATIC if 32BIT
> >         select SPARSE_IRQ
> >         select SYSCTL_EXCEPTION_TRACE
> > diff --git a/arch/riscv/Kconfig.socs b/arch/riscv/Kconfig.socs
> > index 6c88148f1b9b..8a55f6156661 100644
> > --- a/arch/riscv/Kconfig.socs
> > +++ b/arch/riscv/Kconfig.socs
> > @@ -12,6 +12,7 @@ config SOC_SIFIVE
> >
> >  config SOC_VIRT
> >         bool "QEMU Virt Machine"
> > +       select CLINT_TIMER if RISCV_M_MODE
> >         select POWER_RESET
> >         select POWER_RESET_SYSCON
> >         select POWER_RESET_SYSCON_POWEROFF
> > @@ -24,6 +25,7 @@ config SOC_VIRT
> >  config SOC_KENDRYTE
> >         bool "Kendryte K210 SoC"
> >         depends on !MMU
> > +       select CLINT_TIMER if RISCV_M_MODE
> >         select SERIAL_SIFIVE if TTY
> >         select SERIAL_SIFIVE_CONSOLE if TTY
> >         select SIFIVE_PLIC
> > diff --git a/arch/riscv/configs/nommu_virt_defconfig b/arch/riscv/configs/nommu_virt_defconfig
> > index cf74e179bf90..cf9388184aa3 100644
> > --- a/arch/riscv/configs/nommu_virt_defconfig
> > +++ b/arch/riscv/configs/nommu_virt_defconfig
> > @@ -26,6 +26,7 @@ CONFIG_EXPERT=y
> >  CONFIG_SLOB=y
> >  # CONFIG_SLAB_MERGE_DEFAULT is not set
> >  # CONFIG_MMU is not set
> > +CONFIG_SOC_VIRT=y
> >  CONFIG_MAXPHYSMEM_2GB=y
> >  CONFIG_SMP=y
> >  CONFIG_CMDLINE="root=/dev/vda rw earlycon=uart8250,mmio,0x10000000,115200n8 console=ttyS0"
> > @@ -48,7 +49,6 @@ CONFIG_VIRTIO_BLK=y
> >  # CONFIG_SERIO is not set
> >  # CONFIG_LEGACY_PTYS is not set
> >  # CONFIG_LDISC_AUTOLOAD is not set
> > -# CONFIG_DEVMEM is not set
> >  CONFIG_SERIAL_8250=y
> >  # CONFIG_SERIAL_8250_DEPRECATED_OPTIONS is not set
> >  CONFIG_SERIAL_8250_CONSOLE=y
> > @@ -56,16 +56,13 @@ CONFIG_SERIAL_8250_NR_UARTS=1
> >  CONFIG_SERIAL_8250_RUNTIME_UARTS=1
> >  CONFIG_SERIAL_OF_PLATFORM=y
> >  # CONFIG_HW_RANDOM is not set
> > +# CONFIG_DEVMEM is not set
> >  # CONFIG_HWMON is not set
> > -# CONFIG_LCD_CLASS_DEVICE is not set
> > -# CONFIG_BACKLIGHT_CLASS_DEVICE is not set
>
> Why these changes are in the diff ?

These are generated by "make savedefconfig".

To preserve bisectability, I have enabled CONFIG_SOC_VIRT
in nommu_virt_defconfig and I have used "make savedefconfig"
to update nommu_virt_defconfig.

>
> >  # CONFIG_VGA_CONSOLE is not set
> >  # CONFIG_HID is not set
> >  # CONFIG_USB_SUPPORT is not set
> >  CONFIG_VIRTIO_MMIO=y
> >  CONFIG_VIRTIO_MMIO_CMDLINE_DEVICES=y
> > -CONFIG_SIFIVE_PLIC=y
> > -# CONFIG_VALIDATE_FS_PARSER is not set
> >  CONFIG_EXT2_FS=y
> >  # CONFIG_DNOTIFY is not set
> >  # CONFIG_INOTIFY_USER is not set
> > diff --git a/arch/riscv/include/asm/clint.h b/arch/riscv/include/asm/clint.h
> > deleted file mode 100644
> > index adaba98a7d6c..000000000000
> > --- a/arch/riscv/include/asm/clint.h
> > +++ /dev/null
> > @@ -1,14 +0,0 @@
> > -/* SPDX-License-Identifier: GPL-2.0 */
> > -#ifndef _ASM_RISCV_CLINT_H
> > -#define _ASM_RISCV_CLINT_H 1
> > -
> > -#include <linux/io.h>
> > -#include <linux/smp.h>
> > -
> > -#ifdef CONFIG_RISCV_M_MODE
> > -void clint_init_boot_cpu(void);
> > -#else /* CONFIG_RISCV_M_MODE */
> > -#define clint_init_boot_cpu()  do { } while (0)
> > -#endif /* CONFIG_RISCV_M_MODE */
> > -
> > -#endif /* _ASM_RISCV_CLINT_H */
> > diff --git a/arch/riscv/include/asm/timex.h b/arch/riscv/include/asm/timex.h
> > index bad2a7c2cda5..a3fb85d505d4 100644
> > --- a/arch/riscv/include/asm/timex.h
> > +++ b/arch/riscv/include/asm/timex.h
> > @@ -7,41 +7,27 @@
> >  #define _ASM_RISCV_TIMEX_H
> >
> >  #include <asm/csr.h>
> > -#include <asm/mmio.h>
> >
> >  typedef unsigned long cycles_t;
> >
> > -extern u64 __iomem *riscv_time_val;
> > -extern u64 __iomem *riscv_time_cmp;
> > -
> > -#ifdef CONFIG_64BIT
> > -#define mmio_get_cycles()      readq_relaxed(riscv_time_val)
> > -#else
> > -#define mmio_get_cycles()      readl_relaxed(riscv_time_val)
> > -#define mmio_get_cycles_hi()   readl_relaxed(((u32 *)riscv_time_val) + 1)
> > -#endif
> > -
> >  static inline cycles_t get_cycles(void)
> >  {
> > -       if (IS_ENABLED(CONFIG_RISCV_SBI))
> > -               return csr_read(CSR_TIME);
> > -       return mmio_get_cycles();
> > +       return csr_read(CSR_TIME);
> >  }
> >  #define get_cycles get_cycles
> >
> > +static inline u32 get_cycles_hi(void)
> > +{
> > +       return csr_read(CSR_TIMEH);
> > +}
> > +#define get_cycles_hi get_cycles_hi
> > +
> >  #ifdef CONFIG_64BIT
> >  static inline u64 get_cycles64(void)
> >  {
> >         return get_cycles();
> >  }
> >  #else /* CONFIG_64BIT */
> > -static inline u32 get_cycles_hi(void)
> > -{
> > -       if (IS_ENABLED(CONFIG_RISCV_SBI))
> > -               return csr_read(CSR_TIMEH);
> > -       return mmio_get_cycles_hi();
> > -}
> > -
> >  static inline u64 get_cycles64(void)
> >  {
> >         u32 hi, lo;
> > diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
> > index b355cf485671..7edf15643146 100644
> > --- a/arch/riscv/kernel/Makefile
> > +++ b/arch/riscv/kernel/Makefile
> > @@ -31,7 +31,7 @@ obj-y += cacheinfo.o
> >  obj-y  += patch.o
> >  obj-$(CONFIG_MMU) += vdso.o vdso/
> >
> > -obj-$(CONFIG_RISCV_M_MODE)     += clint.o traps_misaligned.o
> > +obj-$(CONFIG_RISCV_M_MODE)     += traps_misaligned.o
> >  obj-$(CONFIG_FPU)              += fpu.o
> >  obj-$(CONFIG_SMP)              += smpboot.o
> >  obj-$(CONFIG_SMP)              += smp.o
> > diff --git a/arch/riscv/kernel/clint.c b/arch/riscv/kernel/clint.c
> > deleted file mode 100644
> > index a9845ee023e2..000000000000
> > --- a/arch/riscv/kernel/clint.c
> > +++ /dev/null
> > @@ -1,63 +0,0 @@
> > -// SPDX-License-Identifier: GPL-2.0
> > -/*
> > - * Copyright (c) 2019 Christoph Hellwig.
> > - */
> > -
> > -#include <linux/io.h>
> > -#include <linux/of_address.h>
> > -#include <linux/smp.h>
> > -#include <linux/types.h>
> > -#include <asm/clint.h>
> > -#include <asm/csr.h>
> > -#include <asm/timex.h>
> > -
> > -/*
> > - * This is the layout used by the SiFive clint, which is also shared by the qemu
> > - * virt platform, and the Kendryte KD210 at least.
> > - */
> > -#define CLINT_IPI_OFF          0
> > -#define CLINT_TIME_CMP_OFF     0x4000
> > -#define CLINT_TIME_VAL_OFF     0xbff8
> > -
> > -u32 __iomem *clint_ipi_base;
> > -
> > -static void clint_send_ipi(const struct cpumask *target)
> > -{
> > -       unsigned int cpu;
> > -
> > -       for_each_cpu(cpu, target)
> > -               writel(1, clint_ipi_base + cpuid_to_hartid_map(cpu));
> > -}
> > -
> > -static void clint_clear_ipi(void)
> > -{
> > -       writel(0, clint_ipi_base + cpuid_to_hartid_map(smp_processor_id()));
> > -}
> > -
> > -static struct riscv_ipi_ops clint_ipi_ops = {
> > -       .ipi_inject = clint_send_ipi,
> > -       .ipi_clear = clint_clear_ipi,
> > -};
> > -
> > -void clint_init_boot_cpu(void)
> > -{
> > -       struct device_node *np;
> > -       void __iomem *base;
> > -
> > -       np = of_find_compatible_node(NULL, NULL, "riscv,clint0");
> > -       if (!np) {
> > -               panic("clint not found");
> > -               return;
> > -       }
> > -
> > -       base = of_iomap(np, 0);
> > -       if (!base)
> > -               panic("could not map CLINT");
> > -
> > -       clint_ipi_base = base + CLINT_IPI_OFF;
> > -       riscv_time_cmp = base + CLINT_TIME_CMP_OFF;
> > -       riscv_time_val = base + CLINT_TIME_VAL_OFF;
> > -
> > -       clint_clear_ipi();
> > -       riscv_set_ipi_ops(&clint_ipi_ops);
> > -}
> > diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> > index f04373be54a6..2c6dd329312b 100644
> > --- a/arch/riscv/kernel/setup.c
> > +++ b/arch/riscv/kernel/setup.c
> > @@ -18,7 +18,6 @@
> >  #include <linux/swiotlb.h>
> >  #include <linux/smp.h>
> >
> > -#include <asm/clint.h>
> >  #include <asm/cpu_ops.h>
> >  #include <asm/setup.h>
> >  #include <asm/sections.h>
> > @@ -79,7 +78,6 @@ void __init setup_arch(char **cmdline_p)
> >  #else
> >         unflatten_device_tree();
> >  #endif
> > -       clint_init_boot_cpu();
> >
> >  #ifdef CONFIG_SWIOTLB
> >         swiotlb_init(1);
> > diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c
> > index 8b85683ce203..07626be78c23 100644
> > --- a/arch/riscv/kernel/smp.c
> > +++ b/arch/riscv/kernel/smp.c
> > @@ -17,7 +17,6 @@
> >  #include <linux/seq_file.h>
> >  #include <linux/delay.h>
> >
> > -#include <asm/clint.h>
> >  #include <asm/sbi.h>
> >  #include <asm/tlbflush.h>
> >  #include <asm/cacheflush.h>
> > diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
> > index 5fe849791bf0..a6cfa9842d4b 100644
> > --- a/arch/riscv/kernel/smpboot.c
> > +++ b/arch/riscv/kernel/smpboot.c
> > @@ -24,7 +24,6 @@
> >  #include <linux/of.h>
> >  #include <linux/sched/task_stack.h>
> >  #include <linux/sched/mm.h>
> > -#include <asm/clint.h>
> >  #include <asm/cpu_ops.h>
> >  #include <asm/irq.h>
> >  #include <asm/mmu_context.h>
> > diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> > index 41f1c147c178..b24449da3022 100644
> > --- a/drivers/clocksource/Kconfig
> > +++ b/drivers/clocksource/Kconfig
> > @@ -648,9 +648,8 @@ config ATCPIT100_TIMER
> >           This option enables support for the Andestech ATCPIT100 timers.
> >
> >  config RISCV_TIMER
> > -       bool "Timer for the RISC-V platform"
> > +       bool "Timer for the RISC-V platform" if COMPILE_TEST
> >         depends on GENERIC_SCHED_CLOCK && RISCV
> > -       default y
> >         select TIMER_PROBE
> >         select TIMER_OF
> >         help
> > diff --git a/drivers/clocksource/timer-riscv.c b/drivers/clocksource/timer-riscv.c
> > index 9de1dabfb126..c51c5ed15aa7 100644
> > --- a/drivers/clocksource/timer-riscv.c
> > +++ b/drivers/clocksource/timer-riscv.c
> > @@ -19,26 +19,13 @@
> >  #include <linux/of_irq.h>
> >  #include <asm/smp.h>
> >  #include <asm/sbi.h>
> > -
> > -u64 __iomem *riscv_time_cmp;
> > -u64 __iomem *riscv_time_val;
> > -
> > -static inline void mmio_set_timer(u64 val)
> > -{
> > -       void __iomem *r;
> > -
> > -       r = riscv_time_cmp + cpuid_to_hartid_map(smp_processor_id());
> > -       writeq_relaxed(val, r);
> > -}
> > +#include <asm/timex.h>
> >
> >  static int riscv_clock_next_event(unsigned long delta,
> >                 struct clock_event_device *ce)
> >  {
> >         csr_set(CSR_IE, IE_TIE);
> > -       if (IS_ENABLED(CONFIG_RISCV_SBI))
> > -               sbi_set_timer(get_cycles64() + delta);
> > -       else
> > -               mmio_set_timer(get_cycles64() + delta);
> > +       sbi_set_timer(get_cycles64() + delta);
> >         return 0;
> >  }
> >
> > --
> > 2.25.1
> >
> >
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
>
> Otherwise, looks good.
>
> Reviewed-by: Atish Patra <atish.patra@wdc.com>
>
> --
> Regards,
> Atish

Regards,
Anup