Re: [RFC PATCH 2/2] RISC-V: Add basic support for SBI v0.2

[Mike Rapoport <rppt@linux.ibm.com>]

On Mon, Aug 26, 2019 at 04:32:56PM -0700, Atish Patra wrote:
> The SBI v0.2 introduces a base extension which is backward compatible
> with v0.1. Implement all helper functions and minimum required SBI
> calls from v0.2 for now. All other base extension function will be
> added later as per need.
> 
> Signed-off-by: Atish Patra <atish.patra@wdc.com>
> ---
>  arch/riscv/include/asm/sbi.h | 68 +++++++++++++++++++++++++++++-------
>  arch/riscv/kernel/Makefile   |  1 +
>  arch/riscv/kernel/sbi.c      | 50 ++++++++++++++++++++++++++
>  arch/riscv/kernel/setup.c    |  2 ++
>  4 files changed, 108 insertions(+), 13 deletions(-)
>  create mode 100644 arch/riscv/kernel/sbi.c
> 
> diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> index 7f5ecaaaa0d7..4a4476956693 100644
> --- a/arch/riscv/include/asm/sbi.h
> +++ b/arch/riscv/include/asm/sbi.h
> @@ -8,7 +8,6 @@
>  
>  #include <linux/types.h>
>  
> -
>  #define SBI_EXT_LEGACY_SET_TIMER 0x0
>  #define SBI_EXT_LEGACY_CONSOLE_PUTCHAR 0x1
>  #define SBI_EXT_LEGACY_CONSOLE_GETCHAR 0x2
> @@ -19,28 +18,61 @@
>  #define SBI_EXT_LEGACY_REMOTE_SFENCE_VMA_ASID 0x7
>  #define SBI_EXT_LEGACY_SHUTDOWN 0x8
>  
> -#define SBI_CALL_LEGACY(which, arg0, arg1, arg2, arg3) ({             \
> +#define SBI_EXT_BASE 0x10
> +
> +enum sbi_ext_base_fid {
> +	SBI_EXT_BASE_GET_SPEC_VERSION = 0,
> +	SBI_EXT_BASE_GET_IMP_ID,
> +	SBI_EXT_BASE_GET_IMP_VERSION,
> +	SBI_EXT_BASE_PROBE_EXT,
> +	SBI_EXT_BASE_GET_MVENDORID,
> +	SBI_EXT_BASE_GET_MARCHID,
> +	SBI_EXT_BASE_GET_MIMPID,
> +};
> +
> +#define SBI_CALL_LEGACY(ext, fid, arg0, arg1, arg2, arg3) ({	\
>  	register uintptr_t a0 asm ("a0") = (uintptr_t)(arg0);	\
>  	register uintptr_t a1 asm ("a1") = (uintptr_t)(arg1);	\
>  	register uintptr_t a2 asm ("a2") = (uintptr_t)(arg2);	\
>  	register uintptr_t a3 asm ("a3") = (uintptr_t)(arg3);	\
> -	register uintptr_t a7 asm ("a7") = (uintptr_t)(which);	\
> +	register uintptr_t a6 asm ("a6") = (uintptr_t)(fid);	\
> +	register uintptr_t a7 asm ("a7") = (uintptr_t)(ext);	\
>  	asm volatile ("ecall"					\
> -		      : "+r" (a0)				\
> -		      : "r" (a1), "r" (a2), "r" (a3), "r" (a7)	\
> +		      : "+r" (a0), "+r" (a1)			\
> +		      : "r" (a2), "r" (a3), "r" (a6), "r" (a7) \

Maybe I'm missing something, but how is this supposed to work on systems
with SBI v0.1? Wouldn't this cause a mismatch in the registers?

>  		      : "memory");				\
>  	a0;							\
>  })
>  
>  /* Lazy implementations until SBI is finalized */
> -#define SBI_CALL_LEGACY_0(which) SBI_CALL_LEGACY(which, 0, 0, 0, 0)
> -#define SBI_CALL_LEGACY_1(which, arg0) SBI_CALL_LEGACY(which, arg0, 0, 0, 0)
> -#define SBI_CALL_LEGACY_2(which, arg0, arg1) \
> -		SBI_CALL_LEGACY(which, arg0, arg1, 0, 0)
> -#define SBI_CALL_LEGACY_3(which, arg0, arg1, arg2) \
> -		SBI_CALL_LEGACY(which, arg0, arg1, arg2, 0)
> -#define SBI_CALL_LEGACY_4(which, arg0, arg1, arg2, arg3) \
> -		SBI_CALL_LEGACY(which, arg0, arg1, arg2, arg3)
> +#define SBI_CALL_LEGACY_0(ext) SBI_CALL_LEGACY(ext, 0, 0, 0, 0, 0)
> +#define SBI_CALL_LEGACY_1(ext, arg0) SBI_CALL_LEGACY(ext, 0, arg0, 0, 0, 0)
> +#define SBI_CALL_LEGACY_2(ext, arg0, arg1) \
> +		SBI_CALL_LEGACY(ext, 0, arg0, arg1, 0, 0)
> +#define SBI_CALL_LEGACY_3(ext, arg0, arg1, arg2) \
> +		SBI_CALL_LEGACY(ext, 0, arg0, arg1, arg2, 0)
> +#define SBI_CALL_LEGACY_4(ext, arg0, arg1, arg2, arg3) \
> +		SBI_CALL_LEGACY(ext, 0, arg0, arg1, arg2, arg3)
> +
> +extern unsigned long sbi_firmware_version;
> +struct sbiret {
> +	long error;
> +	long value;
> +};
> +
> +void riscv_sbi_init(void);
> +struct sbiret riscv_sbi_ecall(int ext, int fid, int arg0, int arg1,
> +			       int arg2, int arg3);
> +
> +#define SBI_CALL_0(ext, fid) riscv_sbi_ecall(ext, fid, 0, 0, 0, 0)
> +#define SBI_CALL_1(ext, fid, arg0) riscv_sbi_ecall(ext, fid, arg0, 0, 0, 0)
> +#define SBI_CALL_2(ext, fid, arg0, arg1) \
> +		riscv_sbi_ecall(ext, fid, arg0, arg1, 0, 0)
> +#define SBI_CALL_3(ext, fid, arg0, arg1, arg2) \
> +		riscv_sbi_ecall(ext, fid, arg0, arg1, arg2, 0)
> +#define SBI_CALL_4(ext, fid, arg0, arg1, arg2, arg3) \
> +		riscv_sbi_ecall(ext, fid, arg0, arg1, arg2, arg3)
> +
>  
>  static inline void sbi_console_putchar(int ch)
>  {
> @@ -99,4 +131,14 @@ static inline void sbi_remote_sfence_vma_asid(const unsigned long *hart_mask,
>  			  start, size, asid);
>  }
>  
> +static inline unsigned long riscv_sbi_major_version(void)
> +{
> +	return (sbi_firmware_version >> 24) & 0x7f;
> +}
> +
> +static inline unsigned long riscv_sbi_minor_version(void)
> +{
> +	return sbi_firmware_version & 0xffffff;
> +}
> +
>  #endif
> diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
> index 2420d37d96de..faf862d26924 100644
> --- a/arch/riscv/kernel/Makefile
> +++ b/arch/riscv/kernel/Makefile
> @@ -17,6 +17,7 @@ obj-y	+= irq.o
>  obj-y	+= process.o
>  obj-y	+= ptrace.o
>  obj-y	+= reset.o
> +obj-y	+= sbi.o
>  obj-y	+= setup.o
>  obj-y	+= signal.o
>  obj-y	+= syscall_table.o
> diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
> new file mode 100644
> index 000000000000..457b8cc0e9d9
> --- /dev/null
> +++ b/arch/riscv/kernel/sbi.c
> @@ -0,0 +1,50 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * SBI initialilization and base extension implementation.
> + *
> + * Copyright (c) 2019 Western Digital Corporation or its affiliates.
> + */
> +
> +#include <asm/sbi.h>
> +#include <linux/sched.h>
> +
> +unsigned long sbi_firmware_version;
> +
> +struct sbiret riscv_sbi_ecall(int ext, int fid, int arg0, int arg1,
> +			     int arg2, int arg3)
> +{
> +	struct sbiret ret;
> +
> +	register uintptr_t a0 asm ("a0") = (uintptr_t)(arg0);
> +	register uintptr_t a1 asm ("a1") = (uintptr_t)(arg1);
> +	register uintptr_t a2 asm ("a2") = (uintptr_t)(arg2);
> +	register uintptr_t a3 asm ("a3") = (uintptr_t)(arg3);
> +	register uintptr_t a6 asm ("a6") = (uintptr_t)(fid);
> +	register uintptr_t a7 asm ("a7") = (uintptr_t)(ext);
> +	asm volatile ("ecall"
> +		      : "+r" (a0), "+r" (a1)
> +		      : "r" (a2), "r" (a3), "r" (a6), "r" (a7)
> +		      : "memory");
> +	ret.error = a0;
> +	ret.value = a1;
> +
> +	return ret;
> +}
> +
> +static struct sbiret sbi_get_spec_version(void)
> +{
> +	return SBI_CALL_0(SBI_EXT_BASE, SBI_EXT_BASE_GET_SPEC_VERSION);
> +}
> +
> +void riscv_sbi_init(void)
> +{
> +	struct sbiret ret;
> +
> +	/* legacy SBI version*/
> +	sbi_firmware_version = 0x1;
> +	ret = sbi_get_spec_version();
> +	if (!ret.error)
> +		sbi_firmware_version = ret.value;
> +	pr_info("SBI version implemented in firmware [%lu:%lu]\n",
> +		riscv_sbi_major_version(), riscv_sbi_minor_version());
> +}
> diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
> index a990a6cb184f..4c324fd398c8 100644
> --- a/arch/riscv/kernel/setup.c
> +++ b/arch/riscv/kernel/setup.c
> @@ -21,6 +21,7 @@
>  #include <asm/sections.h>
>  #include <asm/pgtable.h>
>  #include <asm/smp.h>
> +#include <asm/sbi.h>
>  #include <asm/tlbflush.h>
>  #include <asm/thread_info.h>
>  
> @@ -70,6 +71,7 @@ void __init setup_arch(char **cmdline_p)
>  	swiotlb_init(1);
>  #endif
>  
> +	riscv_sbi_init();
>  #ifdef CONFIG_SMP
>  	setup_smp();
>  #endif
> -- 
> 2.21.0
> 
> 
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-- 
Sincerely yours,
Mike.


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