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Date:   Thu, 04 Jun 2020 13:40:18 -0700 (PDT)
Subject:     Re: [PATCH 2/5] RISC-V: Remove CLINT related code
In-Reply-To: <20200521134544.816918-3-anup.patel@wdc.com>
CC:     Paul Walmsley <paul.walmsley@sifive.com>, aou@eecs.berkeley.edu,
        robh+dt@kernel.org, daniel.lezcano@linaro.org, tglx@linutronix.de,
        Damien Le Moal <Damien.LeMoal@wdc.com>,
        Atish Patra <Atish.Patra@wdc.com>,
        Alistair Francis <Alistair.Francis@wdc.com>,
        anup@brainfault.org, linux-riscv@lists.infradead.org,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org,
        Anup Patel <Anup.Patel@wdc.com>
From:   Palmer Dabbelt <palmer@dabbelt.com>
To:     Anup Patel <Anup.Patel@wdc.com>
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On Thu, 21 May 2020 06:45:41 PDT (-0700), Anup Patel wrote:
> We will be having separate CLINT timer driver which will also
> provide CLINT based IPI operations so let's remove CLINT related
> code from arch/riscv directory.

This will leave the system unbootable, which breaks bisecting.

>
> Signed-off-by: Anup Patel <anup.patel@wdc.com>
> ---
>  arch/riscv/include/asm/clint.h | 39 ------------------------------
>  arch/riscv/kernel/Makefile     |  2 +-
>  arch/riscv/kernel/clint.c      | 44 ----------------------------------
>  arch/riscv/kernel/setup.c      |  2 --
>  arch/riscv/kernel/smp.c        |  1 -
>  arch/riscv/kernel/smpboot.c    |  1 -
>  6 files changed, 1 insertion(+), 88 deletions(-)
>  delete mode 100644 arch/riscv/include/asm/clint.h
>  delete mode 100644 arch/riscv/kernel/clint.c
>
> diff --git a/arch/riscv/include/asm/clint.h b/arch/riscv/include/asm/clint.h
> deleted file mode 100644
> index a279b17a6aad..000000000000
> --- a/arch/riscv/include/asm/clint.h
> +++ /dev/null
> @@ -1,39 +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
> -extern u32 __iomem *clint_ipi_base;
> -
> -void clint_init_boot_cpu(void);
> -
> -static inline void clint_send_ipi_single(unsigned long hartid)
> -{
> -	writel(1, clint_ipi_base + hartid);
> -}
> -
> -static inline void clint_send_ipi_mask(const struct cpumask *mask)
> -{
> -	int cpu;
> -
> -	for_each_cpu(cpu, mask)
> -		clint_send_ipi_single(cpuid_to_hartid_map(cpu));
> -}
> -
> -static inline void clint_clear_ipi(unsigned long hartid)
> -{
> -	writel(0, clint_ipi_base + hartid);
> -}
> -#else /* CONFIG_RISCV_M_MODE */
> -#define clint_init_boot_cpu()	do { } while (0)
> -
> -/* stubs to for code is only reachable under IS_ENABLED(CONFIG_RISCV_M_MODE): */
> -void clint_send_ipi_single(unsigned long hartid);
> -void clint_send_ipi_mask(const struct cpumask *hartid_mask);
> -void clint_clear_ipi(unsigned long hartid);
> -#endif /* CONFIG_RISCV_M_MODE */
> -
> -#endif /* _ASM_RISCV_CLINT_H */
> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
> index d8bbd3207100..529cda705cfe 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 3647980d14c3..000000000000
> --- a/arch/riscv/kernel/clint.c
> +++ /dev/null
> @@ -1,44 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0
> -/*
> - * Copyright (c) 2019 Christoph Hellwig.
> - */
> -
> -#include <linux/io.h>
> -#include <linux/of_address.h>
> -#include <linux/types.h>
> -#include <asm/clint.h>
> -#include <asm/csr.h>
> -#include <asm/timex.h>
> -#include <asm/smp.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;
> -
> -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(boot_cpu_hartid);
> -}
> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> index 145128a7e560..b07a583bf53b 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>
> @@ -76,7 +75,6 @@ void __init setup_arch(char **cmdline_p)
>  	setup_bootmem();
>  	paging_init();
>  	unflatten_device_tree();
> -	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 8375cc5970f6..8a23f1eb5400 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>