[RFC PATCH v5 2/4] lib: sbi: Implement SBI CPPC extension
Anup Patel
anup at brainfault.org
Thu Apr 6 21:30:51 PDT 2023
On Wed, Mar 29, 2023 at 2:27 PM Sunil V L <sunilvl at ventanamicro.com> wrote:
>
> Implement SBI CPPC extension. This extension is only available when
> OpenSBI platform provides a CPPC device to generic library.
>
> Signed-off-by: Sunil V L <sunilvl at ventanamicro.com>
> Reviewed-by: Andrew Jones <ajones at ventanamicro.com>
Looks good to me.
Reviewed-by: Anup Patel <anup at brainfault.org>
Applied this patch to the riscv/opensbi repo.
Thanks,
Anup
> ---
> include/sbi/sbi_cppc.h | 35 +++++++++++++
> lib/sbi/Kconfig | 4 ++
> lib/sbi/objects.mk | 4 ++
> lib/sbi/sbi_cppc.c | 110 +++++++++++++++++++++++++++++++++++++++
> lib/sbi/sbi_ecall_cppc.c | 63 ++++++++++++++++++++++
> 5 files changed, 216 insertions(+)
> create mode 100644 include/sbi/sbi_cppc.h
> create mode 100644 lib/sbi/sbi_cppc.c
> create mode 100644 lib/sbi/sbi_ecall_cppc.c
>
> diff --git a/include/sbi/sbi_cppc.h b/include/sbi/sbi_cppc.h
> new file mode 100644
> index 0000000..edf73f5
> --- /dev/null
> +++ b/include/sbi/sbi_cppc.h
> @@ -0,0 +1,35 @@
> +/*
> + * SPDX-License-Identifier: BSD-2-Clause
> + *
> + * Copyright (c) 2023 Ventana Micro Systems Inc.
> + *
> + */
> +
> +#ifndef __SBI_CPPC_H__
> +#define __SBI_CPPC_H__
> +
> +#include <sbi/sbi_types.h>
> +
> +/** CPPC device */
> +struct sbi_cppc_device {
> + /** Name of the CPPC device */
> + char name[32];
> +
> + /** probe - returns register width if implemented, 0 otherwise */
> + int (*cppc_probe)(unsigned long reg);
> +
> + /** read the cppc register*/
> + int (*cppc_read)(unsigned long reg, uint64_t *val);
> +
> + /** write to the cppc register*/
> + int (*cppc_write)(unsigned long reg, uint64_t val);
> +};
> +
> +int sbi_cppc_probe(unsigned long reg);
> +int sbi_cppc_read(unsigned long reg, uint64_t *val);
> +int sbi_cppc_write(unsigned long reg, uint64_t val);
> +
> +const struct sbi_cppc_device *sbi_cppc_get_device(void);
> +void sbi_cppc_set_device(const struct sbi_cppc_device *dev);
> +
> +#endif
> diff --git a/lib/sbi/Kconfig b/lib/sbi/Kconfig
> index 7eb3273..477775e 100644
> --- a/lib/sbi/Kconfig
> +++ b/lib/sbi/Kconfig
> @@ -34,6 +34,10 @@ config SBI_ECALL_DBCN
> bool "Debug Console extension"
> default y
>
> +config SBI_ECALL_CPPC
> + bool "CPPC extension"
> + default y
> +
> config SBI_ECALL_LEGACY
> bool "SBI v0.1 legacy extensions"
> default y
> diff --git a/lib/sbi/objects.mk b/lib/sbi/objects.mk
> index 770238b..7d691c6 100644
> --- a/lib/sbi/objects.mk
> +++ b/lib/sbi/objects.mk
> @@ -43,6 +43,9 @@ libsbi-objs-$(CONFIG_SBI_ECALL_PMU) += sbi_ecall_pmu.o
> carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_DBCN) += ecall_dbcn
> libsbi-objs-$(CONFIG_SBI_ECALL_DBCN) += sbi_ecall_dbcn.o
>
> +carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_CPPC) += ecall_cppc
> +libsbi-objs-$(CONFIG_SBI_ECALL_CPPC) += sbi_ecall_cppc.o
> +
> carray-sbi_ecall_exts-$(CONFIG_SBI_ECALL_LEGACY) += ecall_legacy
> libsbi-objs-$(CONFIG_SBI_ECALL_LEGACY) += sbi_ecall_legacy.o
>
> @@ -74,3 +77,4 @@ libsbi-objs-y += sbi_tlb.o
> libsbi-objs-y += sbi_trap.o
> libsbi-objs-y += sbi_unpriv.o
> libsbi-objs-y += sbi_expected_trap.o
> +libsbi-objs-y += sbi_cppc.o
> diff --git a/lib/sbi/sbi_cppc.c b/lib/sbi/sbi_cppc.c
> new file mode 100644
> index 0000000..afb60b3
> --- /dev/null
> +++ b/lib/sbi/sbi_cppc.c
> @@ -0,0 +1,110 @@
> +/*
> + * SPDX-License-Identifier: BSD-2-Clause
> + *
> + * Copyright (c) 2023 Ventana Micro Systems Inc.
> + *
> + */
> +
> +#include <sbi/sbi_error.h>
> +#include <sbi/sbi_cppc.h>
> +
> +static const struct sbi_cppc_device *cppc_dev = NULL;
> +
> +const struct sbi_cppc_device *sbi_cppc_get_device(void)
> +{
> + return cppc_dev;
> +}
> +
> +void sbi_cppc_set_device(const struct sbi_cppc_device *dev)
> +{
> + if (!dev || cppc_dev)
> + return;
> +
> + cppc_dev = dev;
> +}
> +
> +static bool sbi_cppc_is_reserved(unsigned long reg)
> +{
> + if ((reg > SBI_CPPC_ACPI_LAST && reg < SBI_CPPC_TRANSITION_LATENCY) ||
> + reg > SBI_CPPC_NON_ACPI_LAST)
> + return true;
> +
> + return false;
> +}
> +
> +static bool sbi_cppc_readable(unsigned long reg)
> +{
> + /* there are no write-only cppc registers currently */
> + return true;
> +}
> +
> +static bool sbi_cppc_writable(unsigned long reg)
> +{
> + switch (reg) {
> + case SBI_CPPC_HIGHEST_PERF:
> + case SBI_CPPC_NOMINAL_PERF:
> + case SBI_CPPC_LOW_NON_LINEAR_PERF:
> + case SBI_CPPC_LOWEST_PERF:
> + case SBI_CPPC_GUARANTEED_PERF:
> + case SBI_CPPC_CTR_WRAP_TIME:
> + case SBI_CPPC_REFERENCE_CTR:
> + case SBI_CPPC_DELIVERED_CTR:
> + case SBI_CPPC_REFERENCE_PERF:
> + case SBI_CPPC_LOWEST_FREQ:
> + case SBI_CPPC_NOMINAL_FREQ:
> + case SBI_CPPC_TRANSITION_LATENCY:
> + return false;
> + }
> +
> + return true;
> +}
> +
> +int sbi_cppc_probe(unsigned long reg)
> +{
> + if (!cppc_dev || !cppc_dev->cppc_probe)
> + return SBI_EFAIL;
> +
> + /* Check whether register is reserved */
> + if (sbi_cppc_is_reserved(reg))
> + return SBI_ERR_INVALID_PARAM;
> +
> + return cppc_dev->cppc_probe(reg);
> +}
> +
> +int sbi_cppc_read(unsigned long reg, uint64_t *val)
> +{
> + int ret;
> +
> + if (!cppc_dev || !cppc_dev->cppc_read)
> + return SBI_EFAIL;
> +
> + /* Check whether register is implemented */
> + ret = sbi_cppc_probe(reg);
> + if (ret <= 0)
> + return SBI_ERR_NOT_SUPPORTED;
> +
> + /* Check whether the register is write-only */
> + if (!sbi_cppc_readable(reg))
> + return SBI_ERR_DENIED;
> +
> + return cppc_dev->cppc_read(reg, val);
> +}
> +
> +int sbi_cppc_write(unsigned long reg, uint64_t val)
> +{
> + int ret;
> +
> + if (!cppc_dev || !cppc_dev->cppc_write)
> + return SBI_EFAIL;
> +
> + /* Check whether register is implemented */
> + ret = sbi_cppc_probe(reg);
> + if (ret <= 0)
> + return SBI_ERR_NOT_SUPPORTED;
> +
> + /* Check whether the register is read-only */
> + if (!sbi_cppc_writable(reg))
> + return SBI_ERR_DENIED;
> +
> + return cppc_dev->cppc_write(reg, val);
> +}
> diff --git a/lib/sbi/sbi_ecall_cppc.c b/lib/sbi/sbi_ecall_cppc.c
> new file mode 100644
> index 0000000..91585f3
> --- /dev/null
> +++ b/lib/sbi/sbi_ecall_cppc.c
> @@ -0,0 +1,63 @@
> +/*
> + * SPDX-License-Identifier: BSD-2-Clause
> + *
> + * Copyright (c) 2023 Ventana Micro Systems Inc.
> + *
> + */
> +
> +#include <sbi/sbi_ecall.h>
> +#include <sbi/sbi_ecall_interface.h>
> +#include <sbi/sbi_error.h>
> +#include <sbi/sbi_trap.h>
> +#include <sbi/sbi_cppc.h>
> +
> +static int sbi_ecall_cppc_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_CPPC_READ:
> + ret = sbi_cppc_read(regs->a0, &temp);
> + *out_val = temp;
> + break;
> + case SBI_EXT_CPPC_READ_HI:
> +#if __riscv_xlen == 32
> + ret = sbi_cppc_read(regs->a0, &temp);
> + *out_val = temp >> 32;
> +#else
> + *out_val = 0;
> +#endif
> + break;
> + case SBI_EXT_CPPC_WRITE:
> + ret = sbi_cppc_write(regs->a0, regs->a1);
> + break;
> + case SBI_EXT_CPPC_PROBE:
> + ret = sbi_cppc_probe(regs->a0);
> + if (ret >= 0) {
> + *out_val = ret;
> + ret = 0;
> + }
> + break;
> + default:
> + ret = SBI_ENOTSUPP;
> + }
> +
> + return ret;
> +}
> +
> +static int sbi_ecall_cppc_probe(unsigned long extid, unsigned long *out_val)
> +{
> + *out_val = sbi_cppc_get_device() ? 1 : 0;
> + return 0;
> +}
> +
> +struct sbi_ecall_extension ecall_cppc = {
> + .extid_start = SBI_EXT_CPPC,
> + .extid_end = SBI_EXT_CPPC,
> + .handle = sbi_ecall_cppc_handler,
> + .probe = sbi_ecall_cppc_probe,
> +};
> --
> 2.34.1
>
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