Message-id: <20150422100700.5d00bbff@amdc2363>
Date:	Wed, 22 Apr 2015 10:07:00 +0200
From:	Lukasz Majewski <l.majewski@...sung.com>
To:	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
Cc:	Thomas Abraham <thomas.ab@...sung.com>,
	Sylwester Nawrocki <s.nawrocki@...sung.com>,
	Mike Turquette <mturquette@...aro.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Kukjin Kim <kgene@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Doug Anderson <dianders@...omium.org>,
	Kevin Hilman <khilman@...aro.org>,
	Heiko Stuebner <heiko@...ech.de>, linux-pm@...r.kernel.org,
	Sachin Kamat <sachin.kamat@...aro.org>,
	Tomasz Figa <tomasz.figa@...il.com>,
	linux-kernel@...r.kernel.org, Chanwoo Choi <cw00.choi@...sung.com>,
	linux-samsung-soc@...r.kernel.org,
	Andreas Faerber <afaerber@...e.de>,
	Javier Martinez Canillas <javier.martinez@...labora.co.uk>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 1/8] cpufreq: arm_big_little: add cluster regulator support

Hi Bartlomiej,

> Add cluster regulator support as a preparation to adding
> generic arm_big_little_dt cpufreq_dt driver support for
> ODROID-XU3 board.  This allows arm_big_little[_dt] driver
> to set not only the frequency but also the voltage (which
> is obtained from operating point's voltage value) for CPU
> clusters.
> 
> Cc: Kukjin Kim <kgene.kim@...sung.com>
> Cc: Doug Anderson <dianders@...omium.org>
> Cc: Javier Martinez Canillas <javier.martinez@...labora.co.uk>
> Cc: Andreas Faerber <afaerber@...e.de>
> Cc: Sachin Kamat <sachin.kamat@...aro.org>
> Cc: Thomas Abraham <thomas.ab@...sung.com>
> Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
> ---
>  .../bindings/cpufreq/arm_big_little_dt.txt         |    4 +
>  drivers/cpufreq/arm_big_little.c                   |  153
> +++++++++++++++++--- 2 files changed, 139 insertions(+), 18
> deletions(-)
> 
> diff --git
> a/Documentation/devicetree/bindings/cpufreq/arm_big_little_dt.txt
> b/Documentation/devicetree/bindings/cpufreq/arm_big_little_dt.txt
> index 0715695..8ca4a12 100644 ---
> a/Documentation/devicetree/bindings/cpufreq/arm_big_little_dt.txt +++
> b/Documentation/devicetree/bindings/cpufreq/arm_big_little_dt.txt @@
> -18,6 +18,10 @@ Required properties: Optional properties:
>  - clock-latency: Specify the possible maximum transition latency for
> clock, in unit of nanoseconds.
> +- cpu-cluster.0-supply: Provides the regulator node supplying
> voltage to CPU
> +  cluster 0.
> +- cpu-cluster.1-supply: Provides the regulator node supplying
> voltage to CPU
> +  cluster 1.
>  
>  Examples:
>  
> diff --git a/drivers/cpufreq/arm_big_little.c
> b/drivers/cpufreq/arm_big_little.c index e1a6ba6..edb461b 100644
> --- a/drivers/cpufreq/arm_big_little.c
> +++ b/drivers/cpufreq/arm_big_little.c
> @@ -31,6 +31,7 @@
>  #include <linux/slab.h>
>  #include <linux/topology.h>
>  #include <linux/types.h>
> +#include <linux/regulator/consumer.h>
>  #include <asm/bL_switcher.h>
>  
>  #include "arm_big_little.h"
> @@ -54,6 +55,9 @@ static bool bL_switching_enabled;
>  
>  static struct cpufreq_arm_bL_ops *arm_bL_ops;
>  static struct clk *clk[MAX_CLUSTERS];
> +static struct regulator *reg[MAX_CLUSTERS];
> +static struct device *cpu_devs[MAX_CLUSTERS];
> +static int transition_latencies[MAX_CLUSTERS];
>  static struct cpufreq_frequency_table *freq_table[MAX_CLUSTERS + 1];
>  static atomic_t cluster_usage[MAX_CLUSTERS + 1];
>  
> @@ -122,7 +126,76 @@ static unsigned int bL_cpufreq_get_rate(unsigned
> int cpu) }
>  }
>  
> -static unsigned int
> +static int
> +bL_cpufreq_set_rate_cluster(u32 cpu, u32 cluster, u32 new_rate)
> +{
> +	unsigned long volt = 0, volt_old = 0;
> +	long freq_Hz;
> +	u32 old_rate;
> +	int ret;
> +
> +	freq_Hz = new_rate * 1000;
> +	old_rate = clk_get_rate(clk[cluster]) / 1000;
> +
> +	if (!IS_ERR(reg[cluster])) {
> +		struct dev_pm_opp *opp;
> +		unsigned long opp_freq;
> +
> +		rcu_read_lock();
> +		opp = dev_pm_opp_find_freq_ceil(cpu_devs[cluster],
> &freq_Hz);
> +		if (IS_ERR(opp)) {
> +			rcu_read_unlock();
> +			pr_err("%s: cpu %d, cluster: %d, failed to
> find OPP for %ld\n",
> +				__func__, cpu, cluster, freq_Hz);
> +			return PTR_ERR(opp);
> +		}
> +		volt = dev_pm_opp_get_voltage(opp);
> +		opp_freq = dev_pm_opp_get_freq(opp);
> +		rcu_read_unlock();
> +		volt_old = regulator_get_voltage(reg[cluster]);
> +		pr_debug("%s: cpu %d, cluster: %d, Found OPP: %ld
> kHz, %ld uV\n",
> +			__func__, cpu, cluster, opp_freq / 1000,
> volt);
> +	}
> +
> +	pr_debug("%s: cpu %d, cluster: %d, %u MHz, %ld mV --> %u
> MHz, %ld mV\n",
> +		__func__, cpu, cluster,
> +		old_rate / 1000, (volt_old > 0) ? volt_old / 1000 :
> -1,
> +		new_rate / 1000, volt ? volt / 1000 : -1);
> +
> +	/* scaling up? scale voltage before frequency */
> +	if (!IS_ERR(reg[cluster]) && new_rate > old_rate) {
> +		ret = regulator_set_voltage_tol(reg[cluster], volt,
> 0);
> +		if (ret) {
> +			pr_err("%s: cpu: %d, cluster: %d, failed to
> scale voltage up: %d\n",
> +				__func__, cpu, cluster, ret);
> +			return ret;
> +		}
> +	}
> +
> +	ret = clk_set_rate(clk[cluster], new_rate * 1000);
> +	if (WARN_ON(ret)) {
> +		pr_err("%s: clk_set_rate failed: %d, cluster: %d\n",
> +			__func__, cluster, ret);
> +		if (!IS_ERR(reg[cluster]) && volt_old > 0)
> +			regulator_set_voltage_tol(reg[cluster],
> volt_old, 0);
> +		return ret;
> +	}
> +
> +	/* scaling down? scale voltage after frequency */
> +	if (!IS_ERR(reg[cluster]) && new_rate < old_rate) {
> +		ret = regulator_set_voltage_tol(reg[cluster], volt,
> 0);
> +		if (ret) {
> +			pr_err("%s: cpu: %d, cluster: %d, failed to
> scale voltage down: %d\n",
> +				__func__, cpu, cluster, ret);
> +			clk_set_rate(clk[cluster], old_rate * 1000);
> +			return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int
>  bL_cpufreq_set_rate(u32 cpu, u32 old_cluster, u32 new_cluster, u32
> rate) {
>  	u32 new_rate, prev_rate;
> @@ -145,22 +218,17 @@ bL_cpufreq_set_rate(u32 cpu, u32 old_cluster,
> u32 new_cluster, u32 rate) pr_debug("%s: cpu: %d, old cluster: %d,
> new cluster: %d, freq: %d\n", __func__, cpu, old_cluster,
> new_cluster, new_rate); 
> -	ret = clk_set_rate(clk[new_cluster], new_rate * 1000);
> -	if (WARN_ON(ret)) {
> -		pr_err("clk_set_rate failed: %d, new cluster: %d\n",
> ret,
> -				new_cluster);
> -		if (bLs) {
> -			per_cpu(cpu_last_req_freq, cpu) = prev_rate;
> -			per_cpu(physical_cluster, cpu) = old_cluster;
> -		}
> -
> -		mutex_unlock(&cluster_lock[new_cluster]);
> -
> -		return ret;
> +	ret = bL_cpufreq_set_rate_cluster(cpu, new_cluster,
> new_rate);
> +	if (ret && bLs) {
> +		per_cpu(cpu_last_req_freq, cpu) = prev_rate;
> +		per_cpu(physical_cluster, cpu) = old_cluster;
>  	}
>  
>  	mutex_unlock(&cluster_lock[new_cluster]);
>  
> +	if (ret)
> +		return ret;
> +
>  	/* Recalc freq for old cluster when switching clusters */
>  	if (old_cluster != new_cluster) {
>  		pr_debug("%s: cpu: %d, old cluster: %d, new cluster:
> %d\n", @@ -174,14 +242,11 @@ bL_cpufreq_set_rate(u32 cpu, u32
> old_cluster, u32 new_cluster, u32 rate) /* Set freq of old cluster if
> there are cpus left on it */ new_rate =
> find_cluster_maxfreq(old_cluster); new_rate =
> ACTUAL_FREQ(old_cluster, new_rate); -
>  		if (new_rate) {
>  			pr_debug("%s: Updating rate of old cluster:
> %d, to freq: %d\n", __func__, old_cluster, new_rate);
>  
> -			if (clk_set_rate(clk[old_cluster], new_rate
> * 1000))
> -				pr_err("%s: clk_set_rate failed: %d,
> old cluster: %d\n",
> -						__func__, ret,
> old_cluster);
> +			bL_cpufreq_set_rate_cluster(cpu,
> old_cluster, new_rate); }
>  		mutex_unlock(&cluster_lock[old_cluster]);
>  	}
> @@ -288,6 +353,8 @@ static void
> _put_cluster_clk_and_freq_table(struct device *cpu_dev) return;
>  
>  	clk_put(clk[cluster]);
> +	if (!IS_ERR(reg[cluster]))
> +		regulator_put(reg[cluster]);
>  	dev_pm_opp_free_cpufreq_table(cpu_dev, &freq_table[cluster]);
>  	if (arm_bL_ops->free_opp_table)
>  		arm_bL_ops->free_opp_table(cpu_dev);
> @@ -321,6 +388,7 @@ static void put_cluster_clk_and_freq_table(struct
> device *cpu_dev) 
>  static int _get_cluster_clk_and_freq_table(struct device *cpu_dev)
>  {
> +	unsigned long min_uV = ~0, max_uV = 0;
>  	u32 cluster = raw_cpu_to_cluster(cpu_dev->id);
>  	char name[14] = "cpu-cluster.";
>  	int ret;
> @@ -335,6 +403,51 @@ static int
> _get_cluster_clk_and_freq_table(struct device *cpu_dev) goto out;
>  	}
>  
> +	name[12] = cluster + '0';
> +	reg[cluster] = regulator_get_optional(cpu_dev, name);
> +	if (!IS_ERR(reg[cluster])) {
> +		unsigned long opp_freq = 0;
> +
> +		dev_dbg(cpu_dev, "%s: reg: %p, cluster: %d\n",
> +			__func__, reg[cluster], cluster);
> +		cpu_devs[cluster] = cpu_dev;
> +
> +		/*
> +		 * Disable any OPPs where the connected regulator
> isn't able to
> +		 * provide the specified voltage and record minimum
> and maximum
> +		 * voltage levels.
> +		 */
> +		while (1) {
> +			struct dev_pm_opp *opp;
> +			unsigned long opp_uV;
> +
> +			rcu_read_lock();
> +			opp = dev_pm_opp_find_freq_ceil(cpu_dev,
> &opp_freq);
> +			if (IS_ERR(opp)) {
> +				rcu_read_unlock();
> +				break;
> +			}
> +			opp_uV = dev_pm_opp_get_voltage(opp);
> +			rcu_read_unlock();
> +
> +			if
> (regulator_is_supported_voltage(reg[cluster], opp_uV,
> +							   opp_uV)) {
> +				if (opp_uV < min_uV)
> +					min_uV = opp_uV;
> +				if (opp_uV > max_uV)
> +					max_uV = opp_uV;
> +			} else {
> +				dev_pm_opp_disable(cpu_dev,
> opp_freq);
> +			}
> +
> +			opp_freq++;
> +		}
> +
> +		ret = regulator_set_voltage_time(reg[cluster],
> min_uV, max_uV);
> +		if (ret > 0)
> +			transition_latencies[cluster] = ret * 1000;
> +	}
> +
>  	ret = dev_pm_opp_init_cpufreq_table(cpu_dev,
> &freq_table[cluster]); if (ret) {
>  		dev_err(cpu_dev, "%s: failed to init cpufreq table,
> cpu: %d, err: %d\n", @@ -342,7 +455,6 @@ static int
> _get_cluster_clk_and_freq_table(struct device *cpu_dev) goto
> free_opp_table; }
>  
> -	name[12] = cluster + '0';
>  	clk[cluster] = clk_get(cpu_dev, name);
>  	if (!IS_ERR(clk[cluster])) {
>  		dev_dbg(cpu_dev, "%s: clk: %p & freq table: %p,
> cluster: %d\n", @@ -469,6 +581,11 @@ static int
> bL_cpufreq_init(struct cpufreq_policy *policy) else
>  		policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
>  
> +	if (cur_cluster < MAX_CLUSTERS &&
> +	    policy->cpuinfo.transition_latency != CPUFREQ_ETERNAL)
> +		policy->cpuinfo.transition_latency
> +			+= transition_latencies[cur_cluster];
> +
>  	if (is_bL_switching_enabled())
>  		per_cpu(cpu_last_req_freq, policy->cpu) =
> clk_get_cpu_rate(policy->cpu); 

Reviewed-by: Lukasz Majewski <l.majewski@...sung.com>

-- 
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group
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