Date: Tue, 26 May 2015 14:52:05 +0100
From: Lee Jones <lee.jones@linaro.org>
To: Richard Fitzgerald <rf@opensource.wolfsonmicro.com>
Cc: broonie@kernel.org, linux-kernel@vger.kernel.org,
        patches@opensource.wolfsonmicro.com
Subject: Re: [PATCH v6 1/1] mfd: arizona: Export functions to control
 subsystem DVFS
Message-ID: <20150526135205.GL11677@x1>
References: <1432047462-31860-1-git-send-email-rf@opensource.wolfsonmicro.com>
 <1432047462-31860-2-git-send-email-rf@opensource.wolfsonmicro.com>
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On Tue, 19 May 2015, Richard Fitzgerald wrote:

> The WM5102, WM8997, WM8998 and WM1814 codecs have an internal dynamic
> clock booster. When this booster is active, the DCVDD voltage must be
> increased. If all the currently active audio paths can run with the root
> SYSCLK we can disable the booster, allowing us to turn down DCVDD voltage
> to save power.
> 
> Previously this was being done by having the booster enable bit set
> as a side-effect of the LDO1 regulator driver, which is unexpected
> behaviour of a regulator and not compatible with using an external
> regulator.
> 
> This patch exports functions to handle the booster enable and
> DCVDD voltage, with each relevant subsystem flagging whether it can
> currently run without the booster. Note that these subsystems are
> stateless and none of them are nestable, so there's no need for
> reference counting, we only need a simple boolean for each subsystem
> of whether their current condition could require the booster or will
> allow us to turn the codec down to lower operating power.

The Arizona MFD has far too much knowledge for my liking.  It's
starting to look like a dumping ground for functionality you're
struggling to find a suitable home for.

Shouldn't this DVFS dump live in drivers/cpufreq?

> Signed-off-by: Richard Fitzgerald <rf@opensource.wolfsonmicro.com>
> ---
>  drivers/mfd/arizona-core.c       |  188 +++++++++++++++++++++++++++++++++++++-
>  include/linux/mfd/arizona/core.h |   13 +++
>  2 files changed, 198 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mfd/arizona-core.c b/drivers/mfd/arizona-core.c
> index 16828cc..2679d33 100644
> --- a/drivers/mfd/arizona-core.c
> +++ b/drivers/mfd/arizona-core.c
> @@ -94,6 +94,122 @@ int arizona_clk32k_disable(struct arizona *arizona)
>  }
>  EXPORT_SYMBOL_GPL(arizona_clk32k_disable);
>  
> +static int arizona_dvfs_apply_boost(struct arizona *arizona)
> +{
> +	int ret;
> +
> +	ret = regulator_set_voltage(arizona->dcvdd, 1800000, 1800000);
> +	if (ret != 0) {
> +		dev_err(arizona->dev,
> +			"Failed to boost DCVDD: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = regmap_update_bits(arizona->regmap,
> +				ARIZONA_DYNAMIC_FREQUENCY_SCALING_1,
> +				ARIZONA_SUBSYS_MAX_FREQ, 1);
> +	if (ret != 0) {
> +		dev_err(arizona->dev,
> +			"Failed to enable subsys max: %d\n", ret);
> +
> +		regulator_set_voltage(arizona->dcvdd, 1200000, 1800000);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +static int arizona_dvfs_remove_boost(struct arizona *arizona)
> +{
> +	int ret;
> +
> +	ret = regmap_update_bits(arizona->regmap,
> +				ARIZONA_DYNAMIC_FREQUENCY_SCALING_1,
> +				ARIZONA_SUBSYS_MAX_FREQ, 0);
> +	if (ret != 0) {
> +		dev_err(arizona->dev,
> +			"Failed to disable subsys max: %d\n", ret);
> +		return ret;
> +	}
> +
> +	ret = regulator_set_voltage(arizona->dcvdd, 1200000, 1800000);
> +	if (ret != 0) {
> +		dev_err(arizona->dev,
> +			"Failed to unboost DCVDD : %d\n", ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +int arizona_dvfs_up(struct arizona *arizona, unsigned int flags)
> +{
> +	unsigned int old_flags;
> +	int ret = 0;
> +
> +	switch (arizona->type) {
> +	case WM5102:
> +	case WM8997:
> +	case WM8998:
> +	case WM1814:
> +		break;
> +	default:
> +		return 0;
> +	}
> +
> +	mutex_lock(&arizona->subsys_max_lock);
> +
> +	old_flags = arizona->subsys_max_rq;
> +	arizona->subsys_max_rq |= flags;
> +
> +	/* If currently caching the change will be applied in runtime resume */
> +	if (arizona->subsys_max_cached) {
> +		dev_dbg(arizona->dev, "subsys_max_cached (dvfs up)\n");
> +		goto out;
> +	}
> +
> +	if ((old_flags == 0) && (arizona->subsys_max_rq != 0))
> +		ret = arizona_dvfs_apply_boost(arizona);
> +out:
> +	mutex_unlock(&arizona->subsys_max_lock);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(arizona_dvfs_up);
> +
> +int arizona_dvfs_down(struct arizona *arizona, unsigned int flags)
> +{
> +	unsigned int old_flags;
> +	int ret = 0;
> +
> +	switch (arizona->type) {
> +	case WM5102:
> +	case WM8997:
> +	case WM8998:
> +	case WM1814:
> +		break;
> +	default:
> +		return 0;
> +	}
> +
> +	mutex_lock(&arizona->subsys_max_lock);
> +
> +	old_flags = arizona->subsys_max_rq;
> +	arizona->subsys_max_rq &= ~flags;
> +
> +	/* If currently caching the change will be applied in runtime resume */
> +	if (arizona->subsys_max_cached) {
> +		dev_dbg(arizona->dev, "subsys_max_cached (dvfs down)\n");
> +		goto out;
> +	}
> +
> +	if ((old_flags != 0) && (arizona->subsys_max_rq == 0))
> +		ret = arizona_dvfs_remove_boost(arizona);
> +out:
> +	mutex_unlock(&arizona->subsys_max_lock);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(arizona_dvfs_down);
> +
>  static irqreturn_t arizona_clkgen_err(int irq, void *data)
>  {
>  	struct arizona *arizona = data;
> @@ -462,6 +578,54 @@ static int wm5102_clear_write_sequencer(struct arizona *arizona)
>  }
>  
>  #ifdef CONFIG_PM
> +static int arizona_restore_dvfs(struct arizona *arizona)
> +{
> +	int ret;
> +
> +	switch (arizona->type) {
> +	case WM5102:
> +	case WM8997:
> +	case WM8998:
> +	case WM1814:
> +		ret = 0;
> +		mutex_lock(&arizona->subsys_max_lock);
> +		if (arizona->subsys_max_rq != 0) {
> +			dev_dbg(arizona->dev, "Restore subsys_max boost\n");
> +			ret = arizona_dvfs_apply_boost(arizona);
> +		}
> +
> +		if (ret == 0)
> +			arizona->subsys_max_cached = false;
> +
> +		mutex_unlock(&arizona->subsys_max_lock);
> +		return ret;
> +	default:
> +		return 0;	/* no DVFS */
> +	}
> +}
> +
> +static int arizona_suspend_dvfs(struct arizona *arizona)
> +{
> +	int ret;
> +
> +	switch (arizona->type) {
> +	case WM5102:
> +	case WM8997:
> +	case WM8998:
> +	case WM1814:
> +		mutex_lock(&arizona->subsys_max_lock);
> +		ret = arizona_dvfs_remove_boost(arizona);
> +
> +		if (ret == 0)
> +			arizona->subsys_max_cached = true;
> +
> +		mutex_unlock(&arizona->subsys_max_lock);
> +		break;
> +	default:
> +		return 0;
> +	}
> +}
> +
>  static int arizona_runtime_resume(struct device *dev)
>  {
>  	struct arizona *arizona = dev_get_drvdata(dev);
> @@ -590,6 +754,12 @@ static int arizona_runtime_resume(struct device *dev)
>  		goto err;
>  	}
>  
> +	ret = arizona_restore_dvfs(arizona);
> +	if (ret) {
> +		dev_err(arizona->dev, "Failed to restore DVFS: %d\n", ret);
> +		goto err;
> +	}
> +
>  	return 0;
>  
>  err:
> @@ -612,6 +782,13 @@ static int arizona_runtime_suspend(struct device *dev)
>  		return ret;
>  	}
>  
> +	/* Must disable DVFS boost before powering down DCVDD */
> +	ret = arizona_suspend_dvfs(arizona);
> +	if (ret) {
> +		dev_err(dev, "Failed to suspend DVFS: %d\n", ret);
> +		return ret;
> +	}
> +
>  	if (arizona->external_dcvdd) {
>  		ret = regmap_update_bits(arizona->regmap,
>  					 ARIZONA_ISOLATION_CONTROL,
> @@ -620,7 +797,7 @@ static int arizona_runtime_suspend(struct device *dev)
>  		if (ret != 0) {
>  			dev_err(arizona->dev, "Failed to isolate DCVDD: %d\n",
>  				ret);
> -			return ret;
> +			goto err;
>  		}
>  	}
>  
> @@ -639,7 +816,7 @@ static int arizona_runtime_suspend(struct device *dev)
>  		if (ret < 0) {
>  			dev_err(arizona->dev,
>  				"Failed to set suspend voltage: %d\n", ret);
> -			return ret;
> +			goto err;
>  		}
>  		break;
>  	case WM5102:
> @@ -650,7 +827,7 @@ static int arizona_runtime_suspend(struct device *dev)
>  				dev_err(arizona->dev,
>  					"Failed to clear write sequencer: %d\n",
>  					ret);
> -				return ret;
> +				goto err;
>  			}
>  		}
>  		break;
> @@ -675,6 +852,10 @@ static int arizona_runtime_suspend(struct device *dev)
>  	}
>  
>  	return 0;
> +
> +err:
> +	arizona_restore_dvfs(arizona);
> +	return ret;
>  }
>  #endif
>  
> @@ -933,6 +1114,7 @@ int arizona_dev_init(struct arizona *arizona)
>  
>  	dev_set_drvdata(arizona->dev, arizona);
>  	mutex_init(&arizona->clk_lock);
> +	mutex_init(&arizona->subsys_max_lock);
>  
>  	if (dev_get_platdata(arizona->dev))
>  		memcpy(&arizona->pdata, dev_get_platdata(arizona->dev),
> diff --git a/include/linux/mfd/arizona/core.h b/include/linux/mfd/arizona/core.h
> index b34a625..f18e4ca 100644
> --- a/include/linux/mfd/arizona/core.h
> +++ b/include/linux/mfd/arizona/core.h
> @@ -136,6 +136,10 @@ struct arizona {
>  	struct mutex clk_lock;
>  	int clk32k_ref;
>  
> +	struct mutex subsys_max_lock;
> +	unsigned int subsys_max_rq;
> +	bool subsys_max_cached;
> +
>  	bool ctrlif_error;
>  
>  	struct snd_soc_dapm_context *dapm;
> @@ -148,8 +152,17 @@ struct arizona {
>  	struct mutex dac_comp_lock;
>  };
>  
> +#define ARIZONA_DVFS_SR1_RQ          0x00000001
> +#define ARIZONA_DVFS_SR2_RQ          0x00000002
> +#define ARIZONA_DVFS_SR3_RQ          0x00000004
> +#define ARIZONA_DVFS_ASR1_RQ         0x00000010
> +#define ARIZONA_DVFS_ASR2_RQ         0x00000020
> +#define ARIZONA_DVFS_ADSP1_RQ        0x00010000
> +
>  int arizona_clk32k_enable(struct arizona *arizona);
>  int arizona_clk32k_disable(struct arizona *arizona);
> +int arizona_dvfs_up(struct arizona *arizona, unsigned int mask);
> +int arizona_dvfs_down(struct arizona *arizona, unsigned int mask);
>  
>  int arizona_request_irq(struct arizona *arizona, int irq, char *name,
>  			irq_handler_t handler, void *data);

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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