Messages in this thread | | | From | Anup Patel <> | Date | Tue, 27 Aug 2019 13:53:23 +0530 | Subject | Re: [RFC PATCH 2/2] RISC-V: Add basic support for SBI v0.2 |
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On Tue, Aug 27, 2019 at 1:28 PM Mike Rapoport <rppt@linux.ibm.com> wrote: > > 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?
The SBI v0.2 has two major changes: 1. New improved calling convention which is backward compatible with SBI v0.1 so older kernels with SBI v0.1 will continue to work as-is. 2. Base set of mandatory SBI v0.2 calls which can be used to detect SBI version, check supported SBI calls and extentions.
Old calling convention in SBI v0.1 was: Parameters: a0 -> arg0 a1 -> arg1 a2 -> arg2 a3 -> arg3 a7 -> function_id Return: a0 -> return value or error code
In SBI v0.2, we have extension and function. Each SBI extension is a set of function. The new calling convention in SBI v0.2 is: Parameters: a0 -> arg0 a1 -> arg1 a2 -> arg2 a3 -> arg3 a6 -> function_id a7 -> extension_id Return: a0 -> error code a1 -> return value (optional)
All legacy SBI v0.1 functions can be thought of as separate extensions. That's how SBI v0.2 will be backward compatible.
Regards, Anup
> > > : "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 > > > > > > _______________________________________________ > > linux-riscv mailing list > > linux-riscv@lists.infradead.org > > http://lists.infradead.org/mailman/listinfo/linux-riscv > > -- > Sincerely yours, > Mike. >
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