linux-kernel - Re: [TEGRA194_CPUFREQ Patch 1/3] firmware: tegra: adding function to get BPMP data

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Date:   Wed, 4 Dec 2019 10:45:24 +0200
From:   Mikko Perttunen <cyndis@...si.fi>
To:     Thierry Reding <thierry.reding@...il.com>,
        Sumit Gupta <sumitg@...dia.com>
Cc:     rjw@...ysocki.net, viresh.kumar@...aro.org,
        catalin.marinas@....com, will@...nel.org, jonathanh@...dia.com,
        talho@...dia.com, linux-pm@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, bbasu@...dia.com,
        mperttunen@...dia.com
Subject: Re: [TEGRA194_CPUFREQ Patch 1/3] firmware: tegra: adding function to
 get BPMP data

The difference here is that whereas on Tegra186 the frequency is managed 
through a specific memory-mapped device, on Tegra194 the frequency is 
managed through a CPU MSR leaving no "specific" node for this property 
apart from the cpu nodes itself.

Now, my original patchset (which this series is based on) did add 
nvidia,bpmp properties on the CPU DT nodes itself and query BPMP based 
on that. A change is still required for that since tegra_bpmp_get() 
currently takes a 'struct device *' which we don't have for a CPU DT node.

Mikko

On 3.12.2019 19.42, Thierry Reding wrote:
> On Tue, Dec 03, 2019 at 11:02:26PM +0530, Sumit Gupta wrote:
>> Adding new function of_tegra_bpmp_get() to get BPMP data.
>> This function can be used by other drivers like cpufreq to
>> get BPMP data without adding any property in respective
>> drivers DT node.
> 
> What's wrong with adding the property in the DT node? We already do that
> for Tegra186's CPU frequency driver, so it makes sense to continue that
> for Tegra194.
> 
> Thierry
> 
>> Signed-off-by: Sumit Gupta <sumitg@...dia.com>
>> ---
>>   drivers/firmware/tegra/bpmp.c | 38 ++++++++++++++++++++++++++++++++++++++
>>   include/soc/tegra/bpmp.h      |  5 +++++
>>   2 files changed, 43 insertions(+)
>>
>> diff --git a/drivers/firmware/tegra/bpmp.c b/drivers/firmware/tegra/bpmp.c
>> index 6741fcd..9c3d7f1 100644
>> --- a/drivers/firmware/tegra/bpmp.c
>> +++ b/drivers/firmware/tegra/bpmp.c
>> @@ -38,6 +38,44 @@ channel_to_ops(struct tegra_bpmp_channel *channel)
>>   	return bpmp->soc->ops;
>>   }
>>   
>> +struct tegra_bpmp *of_tegra_bpmp_get(void)
>> +{
>> +	struct platform_device *pdev;
>> +	struct device_node *bpmp_dev;
>> +	struct tegra_bpmp *bpmp;
>> +
>> +	/* Check for bpmp device status in DT */
>> +	bpmp_dev = of_find_compatible_node(NULL, NULL, "nvidia,tegra186-bpmp");
>> +	if (!bpmp_dev) {
>> +		bpmp = ERR_PTR(-ENODEV);
>> +		goto err_out;
>> +	}
>> +	if (!of_device_is_available(bpmp_dev)) {
>> +		bpmp = ERR_PTR(-ENODEV);
>> +		goto err_put;
>> +	}
>> +
>> +	pdev = of_find_device_by_node(bpmp_dev);
>> +	if (!pdev) {
>> +		bpmp = ERR_PTR(-ENODEV);
>> +		goto err_put;
>> +	}
>> +
>> +	bpmp = platform_get_drvdata(pdev);
>> +	if (!bpmp) {
>> +		bpmp = ERR_PTR(-EPROBE_DEFER);
>> +		put_device(&pdev->dev);
>> +		goto err_put;
>> +	}
>> +
>> +	return bpmp;
>> +err_put:
>> +	of_node_put(bpmp_dev);
>> +err_out:
>> +	return bpmp;
>> +}
>> +EXPORT_SYMBOL_GPL(of_tegra_bpmp_get);
>> +
>>   struct tegra_bpmp *tegra_bpmp_get(struct device *dev)
>>   {
>>   	struct platform_device *pdev;
>> diff --git a/include/soc/tegra/bpmp.h b/include/soc/tegra/bpmp.h
>> index f2604e9..21402d9 100644
>> --- a/include/soc/tegra/bpmp.h
>> +++ b/include/soc/tegra/bpmp.h
>> @@ -107,6 +107,7 @@ struct tegra_bpmp_message {
>>   };
>>   
>>   #if IS_ENABLED(CONFIG_TEGRA_BPMP)
>> +struct tegra_bpmp *of_tegra_bpmp_get(void);
>>   struct tegra_bpmp *tegra_bpmp_get(struct device *dev);
>>   void tegra_bpmp_put(struct tegra_bpmp *bpmp);
>>   int tegra_bpmp_transfer_atomic(struct tegra_bpmp *bpmp,
>> @@ -122,6 +123,10 @@ void tegra_bpmp_free_mrq(struct tegra_bpmp *bpmp, unsigned int mrq,
>>   			 void *data);
>>   bool tegra_bpmp_mrq_is_supported(struct tegra_bpmp *bpmp, unsigned int mrq);
>>   #else
>> +static inline struct tegra_bpmp *of_tegra_bpmp_get(void)
>> +{
>> +	return ERR_PTR(-ENOTSUPP);
>> +}
>>   static inline struct tegra_bpmp *tegra_bpmp_get(struct device *dev)
>>   {
>>   	return ERR_PTR(-ENOTSUPP);
>> -- 
>> 2.7.4
>>