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Date:   Thu, 12 Jan 2023 23:52:26 -0600
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Subject: Re: [PATCH v2 2/6] acpi: cppc: Add auto select register read/write
 support
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To:     Wyes Karny <wyes.karny@amd.com>,
        Rafael J Wysocki <rafael@kernel.org>,
        Huang Rui <ray.huang@amd.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Viresh Kumar <viresh.kumar@linaro.org>, Perry.Yuan@amd.com,
        Ananth Narayan <ananth.narayan@amd.com>, gautham.shenoy@amd.com
Cc:     linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-pm@vger.kernel.org, Bagas Sanjaya <bagasdotme@gmail.com>,
        santosh.shukla@amd.com
References: <20230113052141.2874296-1-wyes.karny@amd.com>
 <20230113052141.2874296-3-wyes.karny@amd.com>
From:   Mario Limonciello <mario.limonciello@amd.com>
In-Reply-To: <20230113052141.2874296-3-wyes.karny@amd.com>
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On 1/12/23 23:21, Wyes Karny wrote:
> For some shared memory based systems, the autonomous selection bit

For some "AMD" shared memory systems.

> needed to be set explicitly. Add autonomous selection register related
> APIs to acpi driver, which amd_pstate driver uses later.
> 
> Signed-off-by: Wyes Karny <wyes.karny@amd.com>

Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>

> ---
>   drivers/acpi/cppc_acpi.c | 97 ++++++++++++++++++++++++++++++++++++++++
>   include/acpi/cppc_acpi.h | 11 +++++
>   2 files changed, 108 insertions(+)
> 
> diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> index c936ff503965..e47b2cfe022e 100644
> --- a/drivers/acpi/cppc_acpi.c
> +++ b/drivers/acpi/cppc_acpi.c
> @@ -1432,6 +1432,103 @@ int cppc_set_epp_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls, bool enable)
>   }
>   EXPORT_SYMBOL_GPL(cppc_set_epp_perf);
>   
> +/*
> + * cppc_get_auto_sel_caps - Read autonomous selection register.
> + * @cpunum : CPU from which to read register.
> + * @perf_caps : struct where autonomous selection register value is updated.
> + */
> +int cppc_get_auto_sel_caps(int cpunum, struct cppc_perf_caps *perf_caps)
> +{
> +	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum);
> +	struct cpc_register_resource *auto_sel_reg;
> +	u64  auto_sel;
> +
> +	if (!cpc_desc) {
> +		pr_debug("No CPC descriptor for CPU:%d\n", cpunum);
> +		return -ENODEV;
> +	}
> +
> +	auto_sel_reg = &cpc_desc->cpc_regs[AUTO_SEL_ENABLE];
> +
> +	if (!CPC_SUPPORTED(auto_sel_reg))
> +		pr_warn_once("Autonomous mode is not unsupported!\n");
> +
> +	if (CPC_IN_PCC(auto_sel_reg)) {
> +		int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpunum);
> +		struct cppc_pcc_data *pcc_ss_data = NULL;
> +		int ret = 0;
> +
> +		if (pcc_ss_id < 0)
> +			return -ENODEV;
> +
> +		pcc_ss_data = pcc_data[pcc_ss_id];
> +
> +		down_write(&pcc_ss_data->pcc_lock);
> +
> +		if (send_pcc_cmd(pcc_ss_id, CMD_READ) >= 0) {
> +			cpc_read(cpunum, auto_sel_reg, &auto_sel);
> +			perf_caps->auto_sel = (bool)auto_sel;
> +		} else {
> +			ret = -EIO;
> +		}
> +
> +		up_write(&pcc_ss_data->pcc_lock);
> +
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(cppc_get_auto_sel_caps);
> +
> +/*
> + * cppc_set_auto_sel - Write autonomous selection register.
> + * @cpunum : CPU to which to write register.
> + * @enable : the desired value of autonomous selection resiter to be updated.
> + */
> +int cppc_set_auto_sel(int cpu, bool enable)
> +{
> +	int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
> +	struct cpc_register_resource *auto_sel_reg;
> +	struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
> +	struct cppc_pcc_data *pcc_ss_data = NULL;
> +	int ret = -EINVAL;
> +
> +	if (!cpc_desc) {
> +		pr_debug("No CPC descriptor for CPU:%d\n", cpu);
> +		return -ENODEV;
> +	}
> +
> +	auto_sel_reg = &cpc_desc->cpc_regs[AUTO_SEL_ENABLE];
> +
> +	if (CPC_IN_PCC(auto_sel_reg)) {
> +		if (pcc_ss_id < 0) {
> +			pr_debug("Invalid pcc_ss_id\n");
> +			return -ENODEV;
> +		}
> +
> +		if (CPC_SUPPORTED(auto_sel_reg)) {
> +			ret = cpc_write(cpu, auto_sel_reg, enable);
> +			if (ret)
> +				return ret;
> +		}
> +
> +		pcc_ss_data = pcc_data[pcc_ss_id];
> +
> +		down_write(&pcc_ss_data->pcc_lock);
> +		/* after writing CPC, transfer the ownership of PCC to platform */
> +		ret = send_pcc_cmd(pcc_ss_id, CMD_WRITE);
> +		up_write(&pcc_ss_data->pcc_lock);
> +	} else {
> +		ret = -ENOTSUPP;
> +		pr_debug("_CPC in PCC is not supported\n");
> +	}
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(cppc_set_auto_sel);
> +
> +
>   /**
>    * cppc_set_enable - Set to enable CPPC on the processor by writing the
>    * Continuous Performance Control package EnableRegister field.
> diff --git a/include/acpi/cppc_acpi.h b/include/acpi/cppc_acpi.h
> index 6b487a5bd638..6126c977ece0 100644
> --- a/include/acpi/cppc_acpi.h
> +++ b/include/acpi/cppc_acpi.h
> @@ -109,6 +109,7 @@ struct cppc_perf_caps {
>   	u32 lowest_freq;
>   	u32 nominal_freq;
>   	u32 energy_perf;
> +	bool auto_sel;
>   };
>   
>   struct cppc_perf_ctrls {
> @@ -153,6 +154,8 @@ extern int cpc_read_ffh(int cpunum, struct cpc_reg *reg, u64 *val);
>   extern int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val);
>   extern int cppc_get_epp_perf(int cpunum, u64 *epp_perf);
>   extern int cppc_set_epp_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls, bool enable);
> +extern int cppc_get_auto_sel_caps(int cpunum, struct cppc_perf_caps *perf_caps);
> +extern int cppc_set_auto_sel(int cpu, bool enable);
>   #else /* !CONFIG_ACPI_CPPC_LIB */
>   static inline int cppc_get_desired_perf(int cpunum, u64 *desired_perf)
>   {
> @@ -214,6 +217,14 @@ static inline int cppc_get_epp_perf(int cpunum, u64 *epp_perf)
>   {
>   	return -ENOTSUPP;
>   }
> +static inline int cppc_set_auto_sel(int cpu, bool enable)
> +{
> +	return -ENOTSUPP;
> +}
> +static inline int cppc_get_auto_sel_caps(int cpunum, struct cppc_perf_caps *perf_caps)
> +{
> +	return -ENOTSUPP;
> +}
>   #endif /* !CONFIG_ACPI_CPPC_LIB */
>   
>   #endif /* _CPPC_ACPI_H*/