[PATCH v2 12/15] lib: sbi: Implement SBI PMU extension

[Anup Patel]

> -----Original Message-----
> From: Atish Patra <atish.patra at wdc.com>
> Sent: 27 May 2021 06:01
> To: opensbi at lists.infradead.org
> Cc: Atish Patra <Atish.Patra at wdc.com>; Anup Patel <Anup.Patel at wdc.com>
> Subject: [PATCH v2 12/15] lib: sbi: Implement SBI PMU extension
> 
> RISC-V SBI specfication 0.3 defines a PMU extension that allows supervisor
> mode to start/stop/configure pmu related events. This patch implements all
> of the functionality defined in the specification.
> 
> Signed-off-by: Atish Patra <atish.patra at wdc.com>
> ---
>  include/sbi/sbi_ecall.h |  1 +
>  lib/sbi/objects.mk      |  1 +
>  lib/sbi/sbi_ecall.c     |  9 +++++
>  lib/sbi/sbi_ecall_pmu.c | 78
> +++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 89 insertions(+)
>  create mode 100644 lib/sbi/sbi_ecall_pmu.c
> 
> diff --git a/include/sbi/sbi_ecall.h b/include/sbi/sbi_ecall.h index
> 63ef866ba2d4..9500d0430429 100644
> --- a/include/sbi/sbi_ecall.h
> +++ b/include/sbi/sbi_ecall.h
> @@ -39,6 +39,7 @@ extern struct sbi_ecall_extension ecall_ipi;  extern struct
> sbi_ecall_extension ecall_vendor;  extern struct sbi_ecall_extension
> ecall_hsm;  extern struct sbi_ecall_extension ecall_srst;
> +extern struct sbi_ecall_extension ecall_pmu;
> 
>  u16 sbi_ecall_version_major(void);
> 
> diff --git a/lib/sbi/objects.mk b/lib/sbi/objects.mk index
> d9068b707854..7096f245ae0c 100644
> --- a/lib/sbi/objects.mk
> +++ b/lib/sbi/objects.mk
> @@ -20,6 +20,7 @@ libsbi-objs-y += sbi_ecall.o  libsbi-objs-y +=
> sbi_ecall_base.o  libsbi-objs-y += sbi_ecall_hsm.o  libsbi-objs-y +=
> sbi_ecall_legacy.o
> +libsbi-objs-y += sbi_ecall_pmu.o
>  libsbi-objs-y += sbi_ecall_replace.o
>  libsbi-objs-y += sbi_ecall_vendor.o
>  libsbi-objs-y += sbi_emulate_csr.o
> diff --git a/lib/sbi/sbi_ecall.c b/lib/sbi/sbi_ecall.c index
> e92a53930460..a87bb7ad1c8d 100644
> --- a/lib/sbi/sbi_ecall.c
> +++ b/lib/sbi/sbi_ecall.c
> @@ -11,6 +11,8 @@
>  #include <sbi/sbi_ecall.h>
>  #include <sbi/sbi_ecall_interface.h>
>  #include <sbi/sbi_error.h>
> +#include <sbi/sbi_hart.h>
> +#include <sbi/sbi_scratch.h>
>  #include <sbi/sbi_trap.h>
> 
>  u16 sbi_ecall_version_major(void)
> @@ -144,6 +146,7 @@ int sbi_ecall_handler(struct sbi_trap_regs *regs)  int
> sbi_ecall_init(void)  {
>  	int ret;
> +	struct sbi_scratch *scratch = sbi_scratch_thishart_ptr();
> 
>  	/* The order of below registrations is performance optimized */
>  	ret = sbi_ecall_register_extension(&ecall_time);
> @@ -164,6 +167,12 @@ int sbi_ecall_init(void)
>  	ret = sbi_ecall_register_extension(&ecall_srst);
>  	if (ret)
>  		return ret;
> +	/* SBI PMU extension is useless without mcount inhibit features */
> +	if (sbi_hart_has_feature(scratch, SBI_HART_HAS_MCOUNTINHIBIT)) {
> +		ret = sbi_ecall_register_extension(&ecall_pmu);
> +		if (ret)
> +			return ret;
> +	}

Instead of this, I would suggest to implement probe() callback of extension
just like SBI SRST extension.

Don't worry about SBI extension look-up performance for now, we will
optimize this separately in sbi_ecall.c

Regards,
Anup

>  	ret = sbi_ecall_register_extension(&ecall_legacy);
>  	if (ret)
>  		return ret;
> diff --git a/lib/sbi/sbi_ecall_pmu.c b/lib/sbi/sbi_ecall_pmu.c new file mode
> 100644 index 000000000000..938bf31b907e
> --- /dev/null
> +++ b/lib/sbi/sbi_ecall_pmu.c
> @@ -0,0 +1,78 @@
> +/*
> + * SPDX-License-Identifier: BSD-2-Clause
> + *
> + * Copyright (c) 2021 Western Digital Corporation or its affiliates.
> + *
> + * Authors:
> + *   Atish Patra <atish.patra at wdc.com>
> + */
> +
> +#include <sbi/sbi_ecall.h>
> +#include <sbi/sbi_ecall_interface.h>
> +#include <sbi/sbi_error.h>
> +#include <sbi/sbi_trap.h>
> +#include <sbi/sbi_version.h>
> +#include <sbi/sbi_pmu.h>
> +#include <sbi/sbi_scratch.h>
> +#include <sbi/riscv_asm.h>
> +
> +static int sbi_ecall_pmu_handler(unsigned long extid, unsigned long funcid,
> +				 const struct sbi_trap_regs *regs,
> +				 unsigned long *out_val,
> +				 struct sbi_trap_info *out_trap)
> +{
> +	int ret = 0;
> +	uint64_t temp;
> +
> +	switch (funcid) {
> +	case SBI_EXT_PMU_NUM_COUNTERS:
> +		ret = sbi_pmu_num_ctr();
> +		if (ret >= 0) {
> +			*out_val = ret;
> +			ret = 0;
> +		}
> +		break;
> +	case SBI_EXT_PMU_COUNTER_GET_INFO:
> +		ret = sbi_pmu_ctr_get_info(regs->a0, out_val);
> +		break;
> +	case SBI_EXT_PMU_COUNTER_CFG_MATCH:
> +#if __riscv_xlen == 32
> +		temp = ((uint64_t)regs->a5 << 32) | regs->a4; #else
> +		temp = regs->a4;
> +#endif
> +		ret = sbi_pmu_ctr_cfg_match(regs->a0, regs->a1, regs->a2,
> +					    regs->a3, temp);
> +		if (ret >= 0) {
> +			*out_val = ret;
> +			ret = 0;
> +		}
> +
> +		break;
> +	case SBI_EXT_PMU_COUNTER_FW_READ:
> +		ret = sbi_pmu_ctr_read(regs->a0, out_val);
> +		break;
> +	case SBI_EXT_PMU_COUNTER_START:
> +
> +#if __riscv_xlen == 32
> +		temp = ((uint64_t)regs->a4 << 32) | regs->a3; #else
> +		temp = regs->a3;
> +#endif
> +		ret = sbi_pmu_ctr_start(regs->a0, regs->a1, regs->a2, temp);
> +		break;
> +	case SBI_EXT_PMU_COUNTER_STOP:
> +		ret = sbi_pmu_ctr_stop(regs->a0, regs->a1, regs->a2);
> +		break;
> +	default:
> +		ret = SBI_ENOTSUPP;
> +	};
> +
> +	return ret;
> +}
> +
> +struct sbi_ecall_extension ecall_pmu = {
> +	.extid_start = SBI_EXT_PMU,
> +	.extid_end = SBI_EXT_PMU,
> +	.handle = sbi_ecall_pmu_handler,
> +};
> --
> 2.25.1