[PATCH v1 -next 0/3] RISC-V: ACPI: Enable CPPC based cpufreq support

[PATCH v1 -next 0/3] RISC-V: ACPI: Enable CPPC based cpufreq support

[Sunil V L]

This series enables the support for "Collaborative Processor Performance
Control (CPPC) on ACPI based RISC-V platforms. It depends on the
encoding of CPPC registers as defined in RISC-V FFH spec [2].

CPPC is described in the ACPI spec [1]. RISC-V FFH spec required to
enable this, is available at [2].

[1] - https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#collaborative-processor-performance-control
[2] - https://github.com/riscv-non-isa/riscv-acpi-ffh/releases/download/v1.0.0/riscv-ffh.pdf

The series is based on the LPI support series.
Based-on: 20240118062930.245937-1-sunilvl@ventanamicro.com
(https://lore.kernel.org/lkml/20240118062930.245937-1-sunilvl@ventanamicro.com/)

Sunil V L (3):
  ACPI: RISC-V: Add CPPC driver
  cpufreq: Move CPPC configs to common Kconfig and add RISC-V
  RISC-V: defconfig: Enable CONFIG_ACPI_CPPC_CPUFREQ

 arch/riscv/configs/defconfig |   1 +
 drivers/acpi/riscv/Makefile  |   1 +
 drivers/acpi/riscv/cppc.c    | 157 +++++++++++++++++++++++++++++++++++
 drivers/cpufreq/Kconfig      |  29 +++++++
 drivers/cpufreq/Kconfig.arm  |  26 ------
 5 files changed, 188 insertions(+), 26 deletions(-)
 create mode 100644 drivers/acpi/riscv/cppc.c

-- 
2.34.1

[PATCH v1 -next 1/3] ACPI: RISC-V: Add CPPC driver

[Sunil V L]

Add cpufreq driver based on ACPI CPPC for RISC-V. The driver uses either
SBI CPPC interfaces or the CSRs to access the CPPC registers as defined
by the RISC-V FFH spec.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
---
 drivers/acpi/riscv/Makefile |   1 +
 drivers/acpi/riscv/cppc.c   | 157 ++++++++++++++++++++++++++++++++++++
 2 files changed, 158 insertions(+)
 create mode 100644 drivers/acpi/riscv/cppc.c

diff --git a/drivers/acpi/riscv/Makefile b/drivers/acpi/riscv/Makefile
index 7309d92dd477..86b0925f612d 100644
--- a/drivers/acpi/riscv/Makefile
+++ b/drivers/acpi/riscv/Makefile
@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
 obj-y					+= rhct.o
 obj-$(CONFIG_ACPI_PROCESSOR_IDLE)	+= cpuidle.o
+obj-$(CONFIG_ACPI_CPPC_LIB)		+= cppc.o
diff --git a/drivers/acpi/riscv/cppc.c b/drivers/acpi/riscv/cppc.c
new file mode 100644
index 000000000000..4cdff387deff
--- /dev/null
+++ b/drivers/acpi/riscv/cppc.c
@@ -0,0 +1,157 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Implement CPPC FFH helper routines for RISC-V.
+ *
+ * Copyright (C) 2024 Ventana Micro Systems Inc.
+ */
+
+#include <acpi/cppc_acpi.h>
+#include <asm/csr.h>
+#include <asm/sbi.h>
+
+#define SBI_EXT_CPPC 0x43505043
+
+/* CPPC interfaces defined in SBI spec */
+#define SBI_CPPC_PROBE			0x0
+#define SBI_CPPC_READ			0x1
+#define SBI_CPPC_READ_HI		0x2
+#define SBI_CPPC_WRITE			0x3
+
+/* RISC-V FFH definitions from RISC-V FFH spec */
+#define FFH_CPPC_TYPE(r)		(((r) & GENMASK_ULL(63, 60)) >> 60)
+#define FFH_CPPC_SBI_REG(r)		((r) & GENMASK(31, 0))
+#define FFH_CPPC_CSR_NUM(r)		((r) & GENMASK(11, 0))
+
+#define FFH_CPPC_SBI			0x1
+#define FFH_CPPC_CSR			0x2
+
+struct sbi_cppc_data {
+	u64 val;
+	u32 reg;
+	struct sbiret ret;
+};
+
+static bool cppc_ext_present;
+
+static int __init sbi_cppc_init(void)
+{
+	if (sbi_spec_version >= sbi_mk_version(2, 0) &&
+	    sbi_probe_extension(SBI_EXT_CPPC) > 0) {
+		pr_info("SBI CPPC extension detected\n");
+		cppc_ext_present = true;
+	} else {
+		pr_info("SBI CPPC extension NOT detected!!\n");
+		cppc_ext_present = false;
+	}
+
+	return 0;
+}
+device_initcall(sbi_cppc_init);
+
+static void sbi_cppc_read(void *read_data)
+{
+	struct sbi_cppc_data *data = (struct sbi_cppc_data *)read_data;
+
+	data->ret = sbi_ecall(SBI_EXT_CPPC, SBI_CPPC_READ,
+			      data->reg, 0, 0, 0, 0, 0);
+}
+
+static void sbi_cppc_write(void *write_data)
+{
+	struct sbi_cppc_data *data = (struct sbi_cppc_data *)write_data;
+
+	data->ret = sbi_ecall(SBI_EXT_CPPC, SBI_CPPC_WRITE,
+			      data->reg, data->val, 0, 0, 0, 0);
+}
+
+static void cppc_ffh_csr_read(void *read_data)
+{
+	struct sbi_cppc_data *data = (struct sbi_cppc_data *)read_data;
+
+	switch (data->reg) {
+	/* Support only TIME CSR for now */
+	case CSR_TIME:
+		data->ret.value = csr_read(CSR_TIME);
+		data->ret.error = 0;
+		break;
+	default:
+		data->ret.error = -EINVAL;
+		break;
+	}
+}
+
+static void cppc_ffh_csr_write(void *write_data)
+{
+	struct sbi_cppc_data *data = (struct sbi_cppc_data *)write_data;
+
+	data->ret.error = -EINVAL;
+}
+
+/*
+ * Refer to drivers/acpi/cppc_acpi.c for the description of the functions
+ * below.
+ */
+bool cpc_ffh_supported(void)
+{
+	return true;
+}
+
+int cpc_read_ffh(int cpu, struct cpc_reg *reg, u64 *val)
+{
+	struct sbi_cppc_data data;
+
+	if (WARN_ON_ONCE(irqs_disabled()))
+		return -EPERM;
+
+	if (FFH_CPPC_TYPE(reg->address) == FFH_CPPC_SBI) {
+		if (!cppc_ext_present)
+			return -EINVAL;
+
+		data.reg = FFH_CPPC_SBI_REG(reg->address);
+
+		smp_call_function_single(cpu, sbi_cppc_read, &data, 1);
+
+		*val = data.ret.value;
+
+		return (data.ret.error) ? sbi_err_map_linux_errno(data.ret.error) : 0;
+	} else if (FFH_CPPC_TYPE(reg->address) == FFH_CPPC_CSR) {
+		data.reg = FFH_CPPC_CSR_NUM(reg->address);
+
+		smp_call_function_single(cpu, cppc_ffh_csr_read, &data, 1);
+
+		*val = data.ret.value;
+
+		return (data.ret.error) ? sbi_err_map_linux_errno(data.ret.error) : 0;
+	}
+
+	return -EINVAL;
+}
+
+int cpc_write_ffh(int cpu, struct cpc_reg *reg, u64 val)
+{
+	struct sbi_cppc_data data;
+
+	if (WARN_ON_ONCE(irqs_disabled()))
+		return -EPERM;
+
+	if (FFH_CPPC_TYPE(reg->address) == FFH_CPPC_SBI) {
+		if (!cppc_ext_present)
+			return -EINVAL;
+
+		data.reg = FFH_CPPC_SBI_REG(reg->address);
+		data.val = val;
+
+		smp_call_function_single(cpu, sbi_cppc_write, &data, 1);
+
+		return (data.ret.error) ? sbi_err_map_linux_errno(data.ret.error) : 0;
+	} else if (FFH_CPPC_TYPE(reg->address) == FFH_CPPC_CSR) {
+		data.reg = FFH_CPPC_CSR_NUM(reg->address);
+		data.val = val;
+
+		smp_call_function_single(cpu, cppc_ffh_csr_write, &data, 1);
+
+		return (data.ret.error) ? sbi_err_map_linux_errno(data.ret.error) : 0;
+	}
+
+	return -EINVAL;
+}
-- 
2.34.1

[PATCH v1 -next 2/3] cpufreq: Move CPPC configs to common Kconfig and add RISC-V

[Sunil V L]

CPPC related config options are currently defined only in ARM specific
file. However, they are required for RISC-V as well. Instead of creating
a new Kconfig.riscv file and duplicating them, move them to the common
Kconfig file and enable RISC-V too.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
---
 drivers/cpufreq/Kconfig     | 29 +++++++++++++++++++++++++++++
 drivers/cpufreq/Kconfig.arm | 26 --------------------------
 2 files changed, 29 insertions(+), 26 deletions(-)

diff --git a/drivers/cpufreq/Kconfig b/drivers/cpufreq/Kconfig
index 35efb53d5492..94e55c40970a 100644
--- a/drivers/cpufreq/Kconfig
+++ b/drivers/cpufreq/Kconfig
@@ -302,4 +302,33 @@ config QORIQ_CPUFREQ
 	  which are capable of changing the CPU's frequency dynamically.
 
 endif
+
+config ACPI_CPPC_CPUFREQ
+	tristate "CPUFreq driver based on the ACPI CPPC spec"
+	depends on ACPI_PROCESSOR
+	depends on ARM || ARM64 || RISCV
+	select ACPI_CPPC_LIB
+	help
+	  This adds a CPUFreq driver which uses CPPC methods
+	  as described in the ACPIv5.1 spec. CPPC stands for
+	  Collaborative Processor Performance Controls. It
+	  is based on an abstract continuous scale of CPU
+	  performance values which allows the remote power
+	  processor to flexibly optimize for power and
+	  performance. CPPC relies on power management firmware
+	  support for its operation.
+
+	  If in doubt, say N.
+
+config ACPI_CPPC_CPUFREQ_FIE
+	bool "Frequency Invariance support for CPPC cpufreq driver"
+	depends on ACPI_CPPC_CPUFREQ && GENERIC_ARCH_TOPOLOGY
+	depends on ARM || ARM64 || RISCV
+	default y
+	help
+	  This extends frequency invariance support in the CPPC cpufreq driver,
+	  by using CPPC delivered and reference performance counters.
+
+	  If in doubt, say N.
+
 endmenu
diff --git a/drivers/cpufreq/Kconfig.arm b/drivers/cpufreq/Kconfig.arm
index f911606897b8..987b3d900a89 100644
--- a/drivers/cpufreq/Kconfig.arm
+++ b/drivers/cpufreq/Kconfig.arm
@@ -3,32 +3,6 @@
 # ARM CPU Frequency scaling drivers
 #
 
-config ACPI_CPPC_CPUFREQ
-	tristate "CPUFreq driver based on the ACPI CPPC spec"
-	depends on ACPI_PROCESSOR
-	select ACPI_CPPC_LIB
-	help
-	  This adds a CPUFreq driver which uses CPPC methods
-	  as described in the ACPIv5.1 spec. CPPC stands for
-	  Collaborative Processor Performance Controls. It
-	  is based on an abstract continuous scale of CPU
-	  performance values which allows the remote power
-	  processor to flexibly optimize for power and
-	  performance. CPPC relies on power management firmware
-	  support for its operation.
-
-	  If in doubt, say N.
-
-config ACPI_CPPC_CPUFREQ_FIE
-	bool "Frequency Invariance support for CPPC cpufreq driver"
-	depends on ACPI_CPPC_CPUFREQ && GENERIC_ARCH_TOPOLOGY
-	default y
-	help
-	  This extends frequency invariance support in the CPPC cpufreq driver,
-	  by using CPPC delivered and reference performance counters.
-
-	  If in doubt, say N.
-
 config ARM_ALLWINNER_SUN50I_CPUFREQ_NVMEM
 	tristate "Allwinner nvmem based SUN50I CPUFreq driver"
 	depends on ARCH_SUNXI
-- 
2.34.1

[PATCH v1 -next 3/3] RISC-V: defconfig: Enable CONFIG_ACPI_CPPC_CPUFREQ

[Sunil V L]

CONFIG_ACPI_CPPC_CPUFREQ is required to enable CPPC for RISC-V.

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
---
 arch/riscv/configs/defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/configs/defconfig b/arch/riscv/configs/defconfig
index eaf34e871e30..2988ecd3eb4d 100644
--- a/arch/riscv/configs/defconfig
+++ b/arch/riscv/configs/defconfig
@@ -44,6 +44,7 @@ CONFIG_CPU_FREQ_GOV_USERSPACE=y
 CONFIG_CPU_FREQ_GOV_ONDEMAND=y
 CONFIG_CPU_FREQ_GOV_CONSERVATIVE=m
 CONFIG_CPUFREQ_DT=y
+CONFIG_ACPI_CPPC_CPUFREQ=m
 CONFIG_VIRTUALIZATION=y
 CONFIG_KVM=m
 CONFIG_ACPI=y
-- 
2.34.1

Re: [PATCH v1 -next 0/3] RISC-V: ACPI: Enable CPPC based cpufreq support

[Pierre Gondois]

The code looks good to me, so FWIW:
Reviewed-by: Pierre Gondois <pierre.gondois@arm.com>

+Sudeep as this touches cppc/arm in case he didn't see the patches

On 2/8/24 04:44, Sunil V L wrote:
> This series enables the support for "Collaborative Processor Performance
> Control (CPPC) on ACPI based RISC-V platforms. It depends on the
> encoding of CPPC registers as defined in RISC-V FFH spec [2].
> 
> CPPC is described in the ACPI spec [1]. RISC-V FFH spec required to
> enable this, is available at [2].
> 
> [1] - https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#collaborative-processor-performance-control
> [2] - https://github.com/riscv-non-isa/riscv-acpi-ffh/releases/download/v1.0.0/riscv-ffh.pdf
> 
> The series is based on the LPI support series.
> Based-on: 20240118062930.245937-1-sunilvl@ventanamicro.com
> (https://lore.kernel.org/lkml/20240118062930.245937-1-sunilvl@ventanamicro.com/)
> 
> Sunil V L (3):
>    ACPI: RISC-V: Add CPPC driver
>    cpufreq: Move CPPC configs to common Kconfig and add RISC-V
>    RISC-V: defconfig: Enable CONFIG_ACPI_CPPC_CPUFREQ
> 
>   arch/riscv/configs/defconfig |   1 +
>   drivers/acpi/riscv/Makefile  |   1 +
>   drivers/acpi/riscv/cppc.c    | 157 +++++++++++++++++++++++++++++++++++
>   drivers/cpufreq/Kconfig      |  29 +++++++
>   drivers/cpufreq/Kconfig.arm  |  26 ------
>   5 files changed, 188 insertions(+), 26 deletions(-)
>   create mode 100644 drivers/acpi/riscv/cppc.c
> 

Re: [PATCH v1 -next 0/3] RISC-V: ACPI: Enable CPPC based cpufreq support

[Rafael J. Wysocki]

On Thu, Feb 8, 2024 at 4:44 AM Sunil V L <sunilvl@ventanamicro.com> wrote:
>
> This series enables the support for "Collaborative Processor Performance
> Control (CPPC) on ACPI based RISC-V platforms. It depends on the
> encoding of CPPC registers as defined in RISC-V FFH spec [2].
>
> CPPC is described in the ACPI spec [1]. RISC-V FFH spec required to
> enable this, is available at [2].
>
> [1] - https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#collaborative-processor-performance-control
> [2] - https://github.com/riscv-non-isa/riscv-acpi-ffh/releases/download/v1.0.0/riscv-ffh.pdf
>
> The series is based on the LPI support series.
> Based-on: 20240118062930.245937-1-sunilvl@ventanamicro.com
> (https://lore.kernel.org/lkml/20240118062930.245937-1-sunilvl@ventanamicro.com/)
>
> Sunil V L (3):
>   ACPI: RISC-V: Add CPPC driver
>   cpufreq: Move CPPC configs to common Kconfig and add RISC-V
>   RISC-V: defconfig: Enable CONFIG_ACPI_CPPC_CPUFREQ
>
>  arch/riscv/configs/defconfig |   1 +
>  drivers/acpi/riscv/Makefile  |   1 +
>  drivers/acpi/riscv/cppc.c    | 157 +++++++++++++++++++++++++++++++++++
>  drivers/cpufreq/Kconfig      |  29 +++++++
>  drivers/cpufreq/Kconfig.arm  |  26 ------
>  5 files changed, 188 insertions(+), 26 deletions(-)
>  create mode 100644 drivers/acpi/riscv/cppc.c
>
> --

This is fine with me, so

Acked-by: Rafael J. Wysocki <rafael@kernel.org>

and it would be good to ask Viresh (who maintains the CPPC cpufreq
driver) for an ACK.

Thanks!

Re: [PATCH v1 -next 2/3] cpufreq: Move CPPC configs to common Kconfig and add RISC-V

[Viresh Kumar]

On 08-02-24, 09:14, Sunil V L wrote:
> CPPC related config options are currently defined only in ARM specific
> file. However, they are required for RISC-V as well. Instead of creating
> a new Kconfig.riscv file and duplicating them, move them to the common
> Kconfig file and enable RISC-V too.
> 
> Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
> ---
>  drivers/cpufreq/Kconfig     | 29 +++++++++++++++++++++++++++++
>  drivers/cpufreq/Kconfig.arm | 26 --------------------------
>  2 files changed, 29 insertions(+), 26 deletions(-)

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

-- 
viresh

Re: [PATCH v1 -next 0/3] RISC-V: ACPI: Enable CPPC based cpufreq support

[Viresh Kumar]

On 12-02-24, 16:24, Rafael J. Wysocki wrote:
> On Thu, Feb 8, 2024 at 4:44 AM Sunil V L <sunilvl@ventanamicro.com> wrote:
> >
> > This series enables the support for "Collaborative Processor Performance
> > Control (CPPC) on ACPI based RISC-V platforms. It depends on the
> > encoding of CPPC registers as defined in RISC-V FFH spec [2].
> >
> > CPPC is described in the ACPI spec [1]. RISC-V FFH spec required to
> > enable this, is available at [2].
> >
> > [1] - https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#collaborative-processor-performance-control
> > [2] - https://github.com/riscv-non-isa/riscv-acpi-ffh/releases/download/v1.0.0/riscv-ffh.pdf
> >
> > The series is based on the LPI support series.
> > Based-on: 20240118062930.245937-1-sunilvl@ventanamicro.com
> > (https://lore.kernel.org/lkml/20240118062930.245937-1-sunilvl@ventanamicro.com/)
> >
> > Sunil V L (3):
> >   ACPI: RISC-V: Add CPPC driver
> >   cpufreq: Move CPPC configs to common Kconfig and add RISC-V
> >   RISC-V: defconfig: Enable CONFIG_ACPI_CPPC_CPUFREQ
> >
> >  arch/riscv/configs/defconfig |   1 +
> >  drivers/acpi/riscv/Makefile  |   1 +
> >  drivers/acpi/riscv/cppc.c    | 157 +++++++++++++++++++++++++++++++++++
> >  drivers/cpufreq/Kconfig      |  29 +++++++
> >  drivers/cpufreq/Kconfig.arm  |  26 ------
> >  5 files changed, 188 insertions(+), 26 deletions(-)
> >  create mode 100644 drivers/acpi/riscv/cppc.c
> >
> > --
> 
> This is fine with me, so
> 
> Acked-by: Rafael J. Wysocki <rafael@kernel.org>
> 
> and it would be good to ask Viresh (who maintains the CPPC cpufreq
> driver) for an ACK.

I have provided my Ack over the cpufreq patch. Thanks.

-- 
viresh

Re: [PATCH v1 -next 0/3] RISC-V: ACPI: Enable CPPC based cpufreq support

[Sudeep Holla]

On Fri, Feb 09, 2024 at 12:11:11PM +0100, Pierre Gondois wrote:
> The code looks good to me, so FWIW:
> Reviewed-by: Pierre Gondois <pierre.gondois@arm.com>
> 
> +Sudeep as this touches cppc/arm in case he didn't see the patches
>

Thanks!

> On 2/8/24 04:44, Sunil V L wrote:
> > This series enables the support for "Collaborative Processor Performance
> > Control (CPPC) on ACPI based RISC-V platforms. It depends on the
> > encoding of CPPC registers as defined in RISC-V FFH spec [2].
> > 
> > CPPC is described in the ACPI spec [1]. RISC-V FFH spec required to
> > enable this, is available at [2].
> > 
> > [1] - https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#collaborative-processor-performance-control
> > [2] - https://github.com/riscv-non-isa/riscv-acpi-ffh/releases/download/v1.0.0/riscv-ffh.pdf
> > 
> > The series is based on the LPI support series.
> > Based-on: 20240118062930.245937-1-sunilvl@ventanamicro.com
> > (https://lore.kernel.org/lkml/20240118062930.245937-1-sunilvl@ventanamicro.com/)
> > 
> > Sunil V L (3):
> >    ACPI: RISC-V: Add CPPC driver
> >    cpufreq: Move CPPC configs to common Kconfig and add RISC-V
> >    RISC-V: defconfig: Enable CONFIG_ACPI_CPPC_CPUFREQ
> >

Looks good to me.

Acked-by: Sudeep Holla <sudeep.holla@arm.com>

--
Regards,
Sudeep

Re: [PATCH v1 -next 0/3] RISC-V: ACPI: Enable CPPC based cpufreq support

[Drew Fustini]

On Thu, Feb 08, 2024 at 09:14:11AM +0530, Sunil V L wrote:
> This series enables the support for "Collaborative Processor Performance
> Control (CPPC) on ACPI based RISC-V platforms. It depends on the
> encoding of CPPC registers as defined in RISC-V FFH spec [2].
> 
> CPPC is described in the ACPI spec [1]. RISC-V FFH spec required to
> enable this, is available at [2].
> 
> [1] - https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#collaborative-processor-performance-control
> [2] - https://github.com/riscv-non-isa/riscv-acpi-ffh/releases/download/v1.0.0/riscv-ffh.pdf
> 
> The series is based on the LPI support series.
> Based-on: 20240118062930.245937-1-sunilvl@ventanamicro.com
> (https://lore.kernel.org/lkml/20240118062930.245937-1-sunilvl@ventanamicro.com/)

Should the https://github.com/vlsunil/qemu/tree/lpi_exp branch also be
used for this CPPC series too?

Thanks,
Drew

Re: [PATCH v1 -next 0/3] RISC-V: ACPI: Enable CPPC based cpufreq support

[Drew Fustini]

On Mon, Mar 18, 2024 at 11:40:34AM -0700, Drew Fustini wrote:
> On Thu, Feb 08, 2024 at 09:14:11AM +0530, Sunil V L wrote:
> > This series enables the support for "Collaborative Processor Performance
> > Control (CPPC) on ACPI based RISC-V platforms. It depends on the
> > encoding of CPPC registers as defined in RISC-V FFH spec [2].
> > 
> > CPPC is described in the ACPI spec [1]. RISC-V FFH spec required to
> > enable this, is available at [2].
> > 
> > [1] - https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#collaborative-processor-performance-control
> > [2] - https://github.com/riscv-non-isa/riscv-acpi-ffh/releases/download/v1.0.0/riscv-ffh.pdf
> > 
> > The series is based on the LPI support series.
> > Based-on: 20240118062930.245937-1-sunilvl@ventanamicro.com
> > (https://lore.kernel.org/lkml/20240118062930.245937-1-sunilvl@ventanamicro.com/)
> 
> Should the https://github.com/vlsunil/qemu/tree/lpi_exp branch also be
> used for this CPPC series too?

I noticed the ventanamicro qemu repo has a dev-upstream branch [1] which
contains 4bb6ba4d0fb9 ("riscv/virt: acpi: Enable CPPC - _CPC and _PSD").
I've built that but I still see 'SBI CPPC extension NOT detected!!' in
the Linux boot log.

I'm using upstream opensbi. It seems that sbi_cppc_probe() fails because
cppc_dev is not set. Nothing in the upstream opensbi repo seems to call
sbi_cppc_set_device(), so I am uncertain how it is possible for it to
work. Is there an opensbi branch I should be using?

Thanks,
Drew

[1] https://github.com/ventanamicro/qemu/tree/dev-upstream

Re: [PATCH v1 -next 0/3] RISC-V: ACPI: Enable CPPC based cpufreq support

[Sunil V L]

On Mon, Mar 18, 2024 at 07:27:34PM -0700, Drew Fustini wrote:
> On Mon, Mar 18, 2024 at 11:40:34AM -0700, Drew Fustini wrote:
> > On Thu, Feb 08, 2024 at 09:14:11AM +0530, Sunil V L wrote:
> > > This series enables the support for "Collaborative Processor Performance
> > > Control (CPPC) on ACPI based RISC-V platforms. It depends on the
> > > encoding of CPPC registers as defined in RISC-V FFH spec [2].
> > > 
> > > CPPC is described in the ACPI spec [1]. RISC-V FFH spec required to
> > > enable this, is available at [2].
> > > 
> > > [1] - https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#collaborative-processor-performance-control
> > > [2] - https://github.com/riscv-non-isa/riscv-acpi-ffh/releases/download/v1.0.0/riscv-ffh.pdf
> > > 
> > > The series is based on the LPI support series.
> > > Based-on: 20240118062930.245937-1-sunilvl@ventanamicro.com
> > > (https://lore.kernel.org/lkml/20240118062930.245937-1-sunilvl@ventanamicro.com/)
> > 
> > Should the https://github.com/vlsunil/qemu/tree/lpi_exp branch also be
> > used for this CPPC series too?
> 
> I noticed the ventanamicro qemu repo has a dev-upstream branch [1] which
> contains 4bb6ba4d0fb9 ("riscv/virt: acpi: Enable CPPC - _CPC and _PSD").
> I've built that but I still see 'SBI CPPC extension NOT detected!!' in
> the Linux boot log.
> 
> I'm using upstream opensbi. It seems that sbi_cppc_probe() fails because
> cppc_dev is not set. Nothing in the upstream opensbi repo seems to call
> sbi_cppc_set_device(), so I am uncertain how it is possible for it to
> work. Is there an opensbi branch I should be using?
> 
> Thanks,
> Drew
> 
> [1] https://github.com/ventanamicro/qemu/tree/dev-upstream

Please use below branches for qemu and opensbi. These are just dummy
objects/interfaces added to test the kernel change which are otherwise
platform specific features.

https://github.com/vlsunil/qemu/tree/lpi_cppc_exp
https://github.com/vlsunil/opensbi/tree/cppc_exp

Regards
Sunil

Re: [PATCH v1 -next 0/3] RISC-V: ACPI: Enable CPPC based cpufreq support

[Drew Fustini]

On Tue, Mar 19, 2024 at 03:50:21PM +0530, Sunil V L wrote:
> On Mon, Mar 18, 2024 at 07:27:34PM -0700, Drew Fustini wrote:
> > On Mon, Mar 18, 2024 at 11:40:34AM -0700, Drew Fustini wrote:
> > > On Thu, Feb 08, 2024 at 09:14:11AM +0530, Sunil V L wrote:
> > > > This series enables the support for "Collaborative Processor Performance
> > > > Control (CPPC) on ACPI based RISC-V platforms. It depends on the
> > > > encoding of CPPC registers as defined in RISC-V FFH spec [2].
> > > > 
> > > > CPPC is described in the ACPI spec [1]. RISC-V FFH spec required to
> > > > enable this, is available at [2].
> > > > 
> > > > [1] - https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#collaborative-processor-performance-control
> > > > [2] - https://github.com/riscv-non-isa/riscv-acpi-ffh/releases/download/v1.0.0/riscv-ffh.pdf
> > > > 
> > > > The series is based on the LPI support series.
> > > > Based-on: 20240118062930.245937-1-sunilvl@ventanamicro.com
> > > > (https://lore.kernel.org/lkml/20240118062930.245937-1-sunilvl@ventanamicro.com/)
> > > 
> > > Should the https://github.com/vlsunil/qemu/tree/lpi_exp branch also be
> > > used for this CPPC series too?
> > 
> > I noticed the ventanamicro qemu repo has a dev-upstream branch [1] which
> > contains 4bb6ba4d0fb9 ("riscv/virt: acpi: Enable CPPC - _CPC and _PSD").
> > I've built that but I still see 'SBI CPPC extension NOT detected!!' in
> > the Linux boot log.
> > 
> > I'm using upstream opensbi. It seems that sbi_cppc_probe() fails because
> > cppc_dev is not set. Nothing in the upstream opensbi repo seems to call
> > sbi_cppc_set_device(), so I am uncertain how it is possible for it to
> > work. Is there an opensbi branch I should be using?
> > 
> > Thanks,
> > Drew
> > 
> > [1] https://github.com/ventanamicro/qemu/tree/dev-upstream
> 
> Please use below branches for qemu and opensbi. These are just dummy
> objects/interfaces added to test the kernel change which are otherwise
> platform specific features.
> 
> https://github.com/vlsunil/qemu/tree/lpi_cppc_exp
> https://github.com/vlsunil/opensbi/tree/cppc_exp

Thank you for providing those branches.

The CPPC extension is now detected okay during boot but I see the
following in the boot log [1]:

[    1.094707] cpufreq: cpufreq_online: ->get() failed

Have you seen that too?

This appears to be from the following in drivers/cpufreq/cpufreq.c

1500         if (cpufreq_driver->get && has_target()) {
1501                 policy->cur = cpufreq_driver->get(policy->cpu);
1502                 if (!policy->cur) {
1503                         ret = -EIO;
1504                         pr_err("%s: ->get() failed\n", __func__);
1505                         goto out_destroy_policy;
1506                 }
1507         }

I'm not very familiar with the cpufreq code yet. My first thought is
that maybe the get() function pointer isn't set correctly?

thanks,
drew

[1] https://gist.github.com/pdp7/00ab047509d25871f87b3dc1b2445eaa

Re: [PATCH v1 -next 0/3] RISC-V: ACPI: Enable CPPC based cpufreq support

[patchwork-bot+linux-riscv]

Hello:

This series was applied to riscv/linux.git (for-next)
by Palmer Dabbelt <palmer@rivosinc.com>:

On Thu,  8 Feb 2024 09:14:11 +0530 you wrote:
> This series enables the support for "Collaborative Processor Performance
> Control (CPPC) on ACPI based RISC-V platforms. It depends on the
> encoding of CPPC registers as defined in RISC-V FFH spec [2].
> 
> CPPC is described in the ACPI spec [1]. RISC-V FFH spec required to
> enable this, is available at [2].
> 
> [...]

Here is the summary with links:
  - [v1,-next,1/3] ACPI: RISC-V: Add CPPC driver
    https://git.kernel.org/riscv/c/30f3ffbee86b
  - [v1,-next,2/3] cpufreq: Move CPPC configs to common Kconfig and add RISC-V
    https://git.kernel.org/riscv/c/7ee1378736f0
  - [v1,-next,3/3] RISC-V: defconfig: Enable CONFIG_ACPI_CPPC_CPUFREQ
    https://git.kernel.org/riscv/c/282b9df4e960

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [PATCH v1 -next 0/3] RISC-V: ACPI: Enable CPPC based cpufreq support

[Drew Fustini]

On Tue, Mar 19, 2024 at 03:50:21PM +0530, Sunil V L wrote:
> On Mon, Mar 18, 2024 at 07:27:34PM -0700, Drew Fustini wrote:
> > On Mon, Mar 18, 2024 at 11:40:34AM -0700, Drew Fustini wrote:
> > > On Thu, Feb 08, 2024 at 09:14:11AM +0530, Sunil V L wrote:
> > > > This series enables the support for "Collaborative Processor Performance
> > > > Control (CPPC) on ACPI based RISC-V platforms. It depends on the
> > > > encoding of CPPC registers as defined in RISC-V FFH spec [2].
> > > > 
> > > > CPPC is described in the ACPI spec [1]. RISC-V FFH spec required to
> > > > enable this, is available at [2].
> > > > 
> > > > [1] - https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#collaborative-processor-performance-control
> > > > [2] - https://github.com/riscv-non-isa/riscv-acpi-ffh/releases/download/v1.0.0/riscv-ffh.pdf
> > > > 
> > > > The series is based on the LPI support series.
> > > > Based-on: 20240118062930.245937-1-sunilvl@ventanamicro.com
> > > > (https://lore.kernel.org/lkml/20240118062930.245937-1-sunilvl@ventanamicro.com/)
> > > 
> > > Should the https://github.com/vlsunil/qemu/tree/lpi_exp branch also be
> > > used for this CPPC series too?
> > 
> > I noticed the ventanamicro qemu repo has a dev-upstream branch [1] which
> > contains 4bb6ba4d0fb9 ("riscv/virt: acpi: Enable CPPC - _CPC and _PSD").
> > I've built that but I still see 'SBI CPPC extension NOT detected!!' in
> > the Linux boot log.
> > 
> > I'm using upstream opensbi. It seems that sbi_cppc_probe() fails because
> > cppc_dev is not set. Nothing in the upstream opensbi repo seems to call
> > sbi_cppc_set_device(), so I am uncertain how it is possible for it to
> > work. Is there an opensbi branch I should be using?
> > 
> > Thanks,
> > Drew
> > 
> > [1] https://github.com/ventanamicro/qemu/tree/dev-upstream
> 
> Please use below branches for qemu and opensbi. These are just dummy
> objects/interfaces added to test the kernel change which are otherwise
> platform specific features.
> 
> https://github.com/vlsunil/qemu/tree/lpi_cppc_exp
> https://github.com/vlsunil/opensbi/tree/cppc_exp

I know the opensbi branch is just for the purpose of testing the kernel
driver. However, I am new to ACPI and I am trying to understand how a
real system might work.

The _CPC register address encoding in the RISC-V FFH spec enables the
SBI CPPC register ID to be specified. But how would SBI firmware know
what physical address corresponds to the CPPC register?

If sbi_cppc_test_write() [1] was implemented for a real system, then how
would it know what physical address to write to for a CPPC register like
SBI_CPPC_DESIRED_PERF?

Thanks,
Drew

[1] https://github.com/vlsunil/opensbi/commit/e23cda47158626f96e5992db00efaaac5dab31b0

Re: [PATCH v1 -next 0/3] RISC-V: ACPI: Enable CPPC based cpufreq support

[Sunil V L]

On Wed, Mar 20, 2024 at 09:12:11PM -0700, Drew Fustini wrote:
> On Tue, Mar 19, 2024 at 03:50:21PM +0530, Sunil V L wrote:
> > On Mon, Mar 18, 2024 at 07:27:34PM -0700, Drew Fustini wrote:
> > > On Mon, Mar 18, 2024 at 11:40:34AM -0700, Drew Fustini wrote:
> > > > On Thu, Feb 08, 2024 at 09:14:11AM +0530, Sunil V L wrote:
> > > > > This series enables the support for "Collaborative Processor Performance
> > > > > Control (CPPC) on ACPI based RISC-V platforms. It depends on the
> > > > > encoding of CPPC registers as defined in RISC-V FFH spec [2].
> > > > > 
> > > > > CPPC is described in the ACPI spec [1]. RISC-V FFH spec required to
> > > > > enable this, is available at [2].
> > > > > 
> > > > > [1] - https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#collaborative-processor-performance-control
> > > > > [2] - https://github.com/riscv-non-isa/riscv-acpi-ffh/releases/download/v1.0.0/riscv-ffh.pdf
> > > > > 
> > > > > The series is based on the LPI support series.
> > > > > Based-on: 20240118062930.245937-1-sunilvl@ventanamicro.com
> > > > > (https://lore.kernel.org/lkml/20240118062930.245937-1-sunilvl@ventanamicro.com/)
> > > > 
> > > > Should the https://github.com/vlsunil/qemu/tree/lpi_exp branch also be
> > > > used for this CPPC series too?
> > > 
> > > I noticed the ventanamicro qemu repo has a dev-upstream branch [1] which
> > > contains 4bb6ba4d0fb9 ("riscv/virt: acpi: Enable CPPC - _CPC and _PSD").
> > > I've built that but I still see 'SBI CPPC extension NOT detected!!' in
> > > the Linux boot log.
> > > 
> > > I'm using upstream opensbi. It seems that sbi_cppc_probe() fails because
> > > cppc_dev is not set. Nothing in the upstream opensbi repo seems to call
> > > sbi_cppc_set_device(), so I am uncertain how it is possible for it to
> > > work. Is there an opensbi branch I should be using?
> > > 
> > > Thanks,
> > > Drew
> > > 
> > > [1] https://github.com/ventanamicro/qemu/tree/dev-upstream
> > 
> > Please use below branches for qemu and opensbi. These are just dummy
> > objects/interfaces added to test the kernel change which are otherwise
> > platform specific features.
> > 
> > https://github.com/vlsunil/qemu/tree/lpi_cppc_exp
> > https://github.com/vlsunil/opensbi/tree/cppc_exp
> 
> I know the opensbi branch is just for the purpose of testing the kernel
> driver. However, I am new to ACPI and I am trying to understand how a
> real system might work.
> 
> The _CPC register address encoding in the RISC-V FFH spec enables the
> SBI CPPC register ID to be specified. But how would SBI firmware know
> what physical address corresponds to the CPPC register?
> 
> If sbi_cppc_test_write() [1] was implemented for a real system, then how
> would it know what physical address to write to for a CPPC register like
> SBI_CPPC_DESIRED_PERF?
> 
The SBI extension provides an abstraction to access the CPPC registers.
SBI implementation for the platform should be aware of how to access a
particular register in the back end when it supports the extension.

Regards,
Sunil