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Subject: Re: [PATCH 2/3] iio: adc: stm32-adc: add analog switches supply
 control
To:     Jonathan Cameron <jic23@kernel.org>
CC:     <robh+dt@kernel.org>, <alexandre.torgue@st.com>,
        <mark.rutland@arm.com>, <mcoquelin.stm32@gmail.com>,
        <lars@metafoo.de>, <knaack.h@gmx.de>, <pmeerw@pmeerw.net>,
        <linux-iio@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>
References: <1560324276-681-1-git-send-email-fabrice.gasnier@st.com>
 <1560324276-681-3-git-send-email-fabrice.gasnier@st.com>
 <20190616160732.124a1eb9@archlinux>
 <f1d4b47a-5910-53fe-5d63-d51da429dacd@st.com>
 <5ea9f65d-2feb-1ec5-1ca1-0cfd2964f160@st.com>
 <20190622120510.2215e8cc@archlinux>
From:   Fabrice Gasnier <fabrice.gasnier@st.com>
Message-ID: <d541c501-2995-95e3-4ed1-d919287aa2f2@st.com>
Date:   Fri, 28 Jun 2019 10:17:36 +0200
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On 6/22/19 1:05 PM, Jonathan Cameron wrote:
> On Wed, 19 Jun 2019 14:38:42 +0200
> Fabrice Gasnier <fabrice.gasnier@st.com> wrote:
> 
>> On 6/17/19 2:43 PM, Fabrice Gasnier wrote:
>>> On 6/16/19 5:07 PM, Jonathan Cameron wrote:  
>>>> On Wed, 12 Jun 2019 09:24:35 +0200
>>>> Fabrice Gasnier <fabrice.gasnier@st.com> wrote:
>>>>  
>>>>> On stm32h7 and stm32mp1, the ADC inputs are multiplexed with analog
>>>>> switches which have reduced performances when their supply is below 2.7V
>>>>> (vdda by default):
>>>>> - vdd supply can be selected if above 2.7V by setting ANASWVDD syscfg bit
>>>>>   (STM32MP1 only).
>>>>> - Voltage booster can be used, to get full ADC performances by setting
>>>>>   BOOSTE/EN_BOOSTER syscfg bit (increases power consumption).
>>>>>
>>>>> Make this optional, since this is a trade-off between analog performance
>>>>> and power consumption.
>>>>>
>>>>> Note: STM32H7 syscfg has a set and clear register for "BOOSTE" control.
>>>>> STM32MP1 has separate set and clear registers pair to control EN_BOOSTER
>>>>> and ANASWVDD bits.
>>>>>
>>>>> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>  
>>>>
>>>> A few minor bits inline, but mostly seems fine to me.
>>>>
>>>> Jonathan
>>>>  
>>>>> ---
>>>>>  drivers/iio/adc/stm32-adc-core.c | 232 ++++++++++++++++++++++++++++++++++++++-
>>>>>  1 file changed, 230 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/drivers/iio/adc/stm32-adc-core.c b/drivers/iio/adc/stm32-adc-core.c
>>>>> index 2327ec1..9d41b16 100644
>>>>> --- a/drivers/iio/adc/stm32-adc-core.c
>>>>> +++ b/drivers/iio/adc/stm32-adc-core.c
>>>>> @@ -14,9 +14,11 @@
>>>>>  #include <linux/irqchip/chained_irq.h>
>>>>>  #include <linux/irqdesc.h>
>>>>>  #include <linux/irqdomain.h>
>>>>> +#include <linux/mfd/syscon.h>
>>>>>  #include <linux/module.h>
>>>>>  #include <linux/of_device.h>
>>>>>  #include <linux/pm_runtime.h>
>>>>> +#include <linux/regmap.h>
>>>>>  #include <linux/regulator/consumer.h>
>>>>>  #include <linux/slab.h>
>>>>>  
>>>>> @@ -51,6 +53,20 @@
>>>>>  
>>>>>  #define STM32_ADC_CORE_SLEEP_DELAY_MS	2000
>>>>>  
>>>>> +/* SYSCFG registers */
>>>>> +#define STM32H7_SYSCFG_PMCR		0x04
>>>>> +#define STM32MP1_SYSCFG_PMCSETR		0x04
>>>>> +#define STM32MP1_SYSCFG_PMCCLRR		0x44
>>>>> +
>>>>> +/* SYSCFG bit fields */
>>>>> +#define STM32H7_SYSCFG_BOOSTE_MASK	BIT(8)
>>>>> +#define STM32MP1_SYSCFG_ANASWVDD_MASK	BIT(9)
>>>>> +
>>>>> +/* SYSCFG capability flags */
>>>>> +#define HAS_VBOOSTER		BIT(0)
>>>>> +#define HAS_ANASWVDD		BIT(1)
>>>>> +#define HAS_CLEAR_REG		BIT(2)
>>>>> +
>>>>>  /**
>>>>>   * stm32_adc_common_regs - stm32 common registers, compatible dependent data
>>>>>   * @csr:	common status register offset
>>>>> @@ -58,6 +74,11 @@
>>>>>   * @eoc1:	adc1 end of conversion flag in @csr
>>>>>   * @eoc2:	adc2 end of conversion flag in @csr
>>>>>   * @eoc3:	adc3 end of conversion flag in @csr
>>>>> + * @has_syscfg: SYSCFG capability flags
>>>>> + * @pmcr:	SYSCFG_PMCSETR/SYSCFG_PMCR register offset
>>>>> + * @pmcc:	SYSCFG_PMCCLRR clear register offset
>>>>> + * @booste_msk:	SYSCFG BOOSTE / EN_BOOSTER bitmask in PMCR & PMCCLRR
>>>>> + * @anaswvdd_msk: SYSCFG ANASWVDD bitmask in PMCR & PMCCLRR
>>>>>   */
>>>>>  struct stm32_adc_common_regs {
>>>>>  	u32 csr;
>>>>> @@ -65,6 +86,11 @@ struct stm32_adc_common_regs {
>>>>>  	u32 eoc1_msk;
>>>>>  	u32 eoc2_msk;
>>>>>  	u32 eoc3_msk;
>>>>> +	unsigned int has_syscfg;
>>>>> +	u32 pmcr;
>>>>> +	u32 pmcc;
>>>>> +	u32 booste_msk;
>>>>> +	u32 anaswvdd_msk;
>>>>>  };
>>>>>  
>>>>>  struct stm32_adc_priv;
>>>>> @@ -87,20 +113,26 @@ struct stm32_adc_priv_cfg {
>>>>>   * @domain:		irq domain reference
>>>>>   * @aclk:		clock reference for the analog circuitry
>>>>>   * @bclk:		bus clock common for all ADCs, depends on part used
>>>>> + * @vdd:		vdd supply reference
>>>>> + * @vdda:		vdda supply reference
>>>>>   * @vref:		regulator reference
>>>>>   * @cfg:		compatible configuration data
>>>>>   * @common:		common data for all ADC instances
>>>>>   * @ccr_bak:		backup CCR in low power mode
>>>>> + * @syscfg:		reference to syscon, system control registers
>>>>>   */
>>>>>  struct stm32_adc_priv {
>>>>>  	int				irq[STM32_ADC_MAX_ADCS];
>>>>>  	struct irq_domain		*domain;
>>>>>  	struct clk			*aclk;
>>>>>  	struct clk			*bclk;
>>>>> +	struct regulator		*vdd;
>>>>> +	struct regulator		*vdda;
>>>>>  	struct regulator		*vref;
>>>>>  	const struct stm32_adc_priv_cfg	*cfg;
>>>>>  	struct stm32_adc_common		common;
>>>>>  	u32				ccr_bak;
>>>>> +	struct regmap			*syscfg;
>>>>>  };
>>>>>  
>>>>>  static struct stm32_adc_priv *to_stm32_adc_priv(struct stm32_adc_common *com)
>>>>> @@ -284,6 +316,22 @@ static const struct stm32_adc_common_regs stm32h7_adc_common_regs = {
>>>>>  	.ccr = STM32H7_ADC_CCR,
>>>>>  	.eoc1_msk = STM32H7_EOC_MST,
>>>>>  	.eoc2_msk = STM32H7_EOC_SLV,
>>>>> +	.has_syscfg = HAS_VBOOSTER,
>>>>> +	.pmcr = STM32H7_SYSCFG_PMCR,
>>>>> +	.booste_msk = STM32H7_SYSCFG_BOOSTE_MASK,
>>>>> +};
>>>>> +
>>>>> +/* STM32MP1 common registers definitions */
>>>>> +static const struct stm32_adc_common_regs stm32mp1_adc_common_regs = {
>>>>> +	.csr = STM32H7_ADC_CSR,
>>>>> +	.ccr = STM32H7_ADC_CCR,
>>>>> +	.eoc1_msk = STM32H7_EOC_MST,
>>>>> +	.eoc2_msk = STM32H7_EOC_SLV,
>>>>> +	.has_syscfg =  HAS_VBOOSTER | HAS_ANASWVDD | HAS_CLEAR_REG,  
>>>>
>>>> Extra space after =  
>>>
>>> Hi Jonathan,
>>>
>>> Oops, I'll fix it in v2.
>>>   
>>>>
>>>>  
>>>>> +	.pmcr = STM32MP1_SYSCFG_PMCSETR,
>>>>> +	.pmcc = STM32MP1_SYSCFG_PMCCLRR,
>>>>> +	.booste_msk = STM32H7_SYSCFG_BOOSTE_MASK,
>>>>> +	.anaswvdd_msk = STM32MP1_SYSCFG_ANASWVDD_MASK,
>>>>>  };
>>>>>  
>>>>>  /* ADC common interrupt for all instances */
>>>>> @@ -388,16 +436,145 @@ static void stm32_adc_irq_remove(struct platform_device *pdev,
>>>>>  	}
>>>>>  }
>>>>>  
>>>>> +static int stm32_adc_core_switches_supply_en(struct device *dev)
>>>>> +{
>>>>> +	struct stm32_adc_common *common = dev_get_drvdata(dev);
>>>>> +	struct stm32_adc_priv *priv = to_stm32_adc_priv(common);
>>>>> +	const struct stm32_adc_common_regs *regs = priv->cfg->regs;
>>>>> +	int ret, vdda, vdd = 0;
>>>>> +	u32 mask, clrmask, setmask = 0;
>>>>> +
>>>>> +	/*
>>>>> +	 * On STM32H7 and STM32MP1, the ADC inputs are multiplexed with analog
>>>>> +	 * switches (via PCSEL) which have reduced performances when their
>>>>> +	 * supply is below 2.7V (vdda by default):
>>>>> +	 * - Voltage booster can be used, to get full ADC performances
>>>>> +	 *   (increases power consumption).
>>>>> +	 * - Vdd can be used to supply them, if above 2.7V (STM32MP1 only).
>>>>> +	 *
>>>>> +	 * This is optional, as this is a trade-off between analog performance
>>>>> +	 * and power consumption.
>>>>> +	 */
>>>>> +	if (!regs->has_syscfg || !priv->vdda || !priv->syscfg) {
>>>>> +		dev_dbg(dev, "Not configuring analog switches\n");
>>>>> +		return 0;
>>>>> +	}
>>>>> +
>>>>> +	ret = regulator_enable(priv->vdda);
>>>>> +	if (ret < 0) {
>>>>> +		dev_err(dev, "vdda enable failed %d\n", ret);
>>>>> +		return ret;
>>>>> +	}
>>>>> +
>>>>> +	ret = regulator_get_voltage(priv->vdda);
>>>>> +	if (ret < 0) {
>>>>> +		dev_err(dev, "vdda get voltage failed %d\n", ret);
>>>>> +		goto vdda_dis;
>>>>> +	}
>>>>> +	vdda = ret;
>>>>> +  
>>>> We only need to do the following block if vdaa is too low.  Should probably
>>>> not turn on vdd if there is not chance we are going to use it?  
>>>
>>> You're right, then I probably need to move the regulator_get_voltage()
>>> call at probe time, to avoid enabling it for nothing at runtime. (e.g.
>>> to figure out it's not going to be used).
>>> In fact, vdd is used also for other things on the platform (I/Os, other
>>> supplies...), and is marked "always-on" in the device tree. But I
>>> understand your point.
>>>
>>> I'll rework this and send a v2.  
>>
>> Hi Jonathan,
>>
>> When reworking this part, I figured out the vdda should be described as
>> required supply for the STM32 ADC. So I pushed out a fix series to
>> address this "Add missing vdda-supply to STM32 ADC". I'll resume v2 of
>> this series that has some dependencies on the fix series .
> 
> Cool. Given timing  I'm taking fixes and new stuff through the togreg
> branch anyway at the moment so dependencies on fixes are easier than
> normal for the next week or so ;)

Hi Jonathan

I did some additional changes at my end. Just for reference, you can see
"regulator: add support for the STM32 ADC booster" series here:
https://lkml.org/lkml/2019/6/28/188

I think the proper way to handle the booster is to have it fully
described as a regulator (that's one). This will also simplify handling
it here.

I'll resume this series once the regulator series has been discussed.

Many thanks,
Best regards,
Fabrice

> 
> Jonathan
> 
>>
>> Thanks
>> Best Regards,
>> Fabrice
>>
>>>
>>> Thanks,
>>> Fabrice
>>>   
>>>>  
>>>>> +	if (priv->vdd && regs->has_syscfg & HAS_ANASWVDD) {
>>>>> +		ret = regulator_enable(priv->vdd);
>>>>> +		if (ret < 0) {
>>>>> +			dev_err(dev, "vdd enable failed %d\n", ret);
>>>>> +			goto vdda_dis;
>>>>> +		}
>>>>> +
>>>>> +		ret = regulator_get_voltage(priv->vdd);
>>>>> +		if (ret < 0) {
>>>>> +			dev_err(dev, "vdd get voltage failed %d\n", ret);
>>>>> +			goto vdd_dis;
>>>>> +		}
>>>>> +		vdd = ret;
>>>>> +	}
>>>>> +
>>>>> +	/*
>>>>> +	 * Recommended settings for ANASWVDD and EN_BOOSTER:
>>>>> +	 * - vdda < 2.7V but vdd > 2.7V: ANASWVDD = 1, EN_BOOSTER = 0 (stm32mp1)
>>>>> +	 * - vdda < 2.7V and vdd < 2.7V: ANASWVDD = 0, EN_BOOSTER = 1
>>>>> +	 * - vdda >= 2.7V:               ANASWVDD = 0, EN_BOOSTER = 0 (default)
>>>>> +	 */
>>>>> +	if (vdda < 2700000) {
>>>>> +		if (vdd > 2700000) {
>>>>> +			dev_dbg(dev, "analog switches supplied by vdd\n");
>>>>> +			setmask = regs->anaswvdd_msk;
>>>>> +			clrmask = regs->booste_msk;
>>>>> +		} else {
>>>>> +			dev_dbg(dev, "Enabling voltage booster\n");
>>>>> +			setmask = regs->booste_msk;
>>>>> +			clrmask = regs->anaswvdd_msk;
>>>>> +		}
>>>>> +	} else {
>>>>> +		dev_dbg(dev, "analog switches supplied by vdda\n");
>>>>> +		clrmask = regs->booste_msk | regs->anaswvdd_msk;
>>>>> +	}
>>>>> +
>>>>> +	mask = regs->booste_msk | regs->anaswvdd_msk;
>>>>> +	if (regs->has_syscfg & HAS_CLEAR_REG) {
>>>>> +		ret = regmap_write(priv->syscfg, regs->pmcc, clrmask);
>>>>> +		if (ret) {
>>>>> +			dev_err(dev, "syscfg clear failed, %d\n", ret);
>>>>> +			goto vdd_dis;
>>>>> +		}
>>>>> +		mask = setmask;
>>>>> +	}
>>>>> +
>>>>> +	ret = regmap_update_bits(priv->syscfg, regs->pmcr, mask, setmask);
>>>>> +	if (ret) {
>>>>> +		dev_err(dev, "syscfg update failed, %d\n", ret);
>>>>> +		goto vdd_dis;
>>>>> +	}
>>>>> +
>>>>> +	/* Booster voltage can take up to 50 us to stabilize */
>>>>> +	if (setmask & regs->booste_msk)
>>>>> +		usleep_range(50, 100);
>>>>> +
>>>>> +	return ret;
>>>>> +
>>>>> +vdd_dis:
>>>>> +	if (priv->vdd && (regs->has_syscfg & HAS_ANASWVDD))
>>>>> +		regulator_disable(priv->vdd);
>>>>> +vdda_dis:
>>>>> +	regulator_disable(priv->vdda);
>>>>> +
>>>>> +	return ret;
>>>>> +}
>>>>> +
>>>>> +static void stm32_adc_core_switches_supply_dis(struct device *dev)
>>>>> +{
>>>>> +	struct stm32_adc_common *common = dev_get_drvdata(dev);
>>>>> +	struct stm32_adc_priv *priv = to_stm32_adc_priv(common);
>>>>> +	const struct stm32_adc_common_regs *regs = priv->cfg->regs;
>>>>> +	u32 mask = regs->booste_msk | regs->anaswvdd_msk;
>>>>> +
>>>>> +	if (!regs->has_syscfg || !priv->vdda || !priv->syscfg)
>>>>> +		return;
>>>>> +
>>>>> +	if (regs->has_syscfg & HAS_CLEAR_REG)
>>>>> +		regmap_write(priv->syscfg, regs->pmcc, mask);
>>>>> +	else
>>>>> +		regmap_update_bits(priv->syscfg, regs->pmcr, mask, 0);
>>>>> +
>>>>> +	if (priv->vdd && (regs->has_syscfg & HAS_ANASWVDD))
>>>>> +		regulator_disable(priv->vdd);
>>>>> +
>>>>> +	regulator_disable(priv->vdda);
>>>>> +}
>>>>> +
>>>>>  static int stm32_adc_core_hw_start(struct device *dev)
>>>>>  {
>>>>>  	struct stm32_adc_common *common = dev_get_drvdata(dev);
>>>>>  	struct stm32_adc_priv *priv = to_stm32_adc_priv(common);
>>>>>  	int ret;
>>>>>  
>>>>> +	ret = stm32_adc_core_switches_supply_en(dev);
>>>>> +	if (ret < 0)
>>>>> +		return ret;
>>>>> +
>>>>>  	ret = regulator_enable(priv->vref);
>>>>>  	if (ret < 0) {
>>>>>  		dev_err(dev, "vref enable failed\n");
>>>>> -		return ret;
>>>>> +		goto err_switches_disable;
>>>>>  	}
>>>>>  
>>>>>  	if (priv->bclk) {
>>>>> @@ -425,6 +602,8 @@ static int stm32_adc_core_hw_start(struct device *dev)
>>>>>  		clk_disable_unprepare(priv->bclk);
>>>>>  err_regulator_disable:
>>>>>  	regulator_disable(priv->vref);
>>>>> +err_switches_disable:
>>>>> +	stm32_adc_core_switches_supply_dis(dev);
>>>>>  
>>>>>  	return ret;
>>>>>  }
>>>>> @@ -441,6 +620,24 @@ static void stm32_adc_core_hw_stop(struct device *dev)
>>>>>  	if (priv->bclk)
>>>>>  		clk_disable_unprepare(priv->bclk);
>>>>>  	regulator_disable(priv->vref);
>>>>> +	stm32_adc_core_switches_supply_dis(dev);
>>>>> +}
>>>>> +
>>>>> +static int stm32_adc_core_syscfg_probe(struct device_node *np,
>>>>> +				       struct stm32_adc_priv *priv)
>>>>> +{
>>>>> +	if (!priv->cfg->regs->has_syscfg)
>>>>> +		return 0;
>>>>> +
>>>>> +	priv->syscfg = syscon_regmap_lookup_by_phandle(np, "st,syscfg");
>>>>> +	if (IS_ERR(priv->syscfg)) {
>>>>> +		/* Optional */
>>>>> +		if (PTR_ERR(priv->syscfg) != -ENODEV)
>>>>> +			return PTR_ERR(priv->syscfg);
>>>>> +		priv->syscfg = NULL;
>>>>> +	}
>>>>> +
>>>>> +	return 0;
>>>>>  }
>>>>>  
>>>>>  static int stm32_adc_probe(struct platform_device *pdev)
>>>>> @@ -475,6 +672,30 @@ static int stm32_adc_probe(struct platform_device *pdev)
>>>>>  		return ret;
>>>>>  	}
>>>>>  
>>>>> +	priv->vdda = devm_regulator_get_optional(&pdev->dev, "vdda");
>>>>> +	if (IS_ERR(priv->vdda)) {
>>>>> +		ret = PTR_ERR(priv->vdda);
>>>>> +		if (ret != -ENODEV) {
>>>>> +			if (ret != -EPROBE_DEFER)
>>>>> +				dev_err(&pdev->dev, "vdda get failed, %d\n",
>>>>> +					ret);
>>>>> +			return ret;
>>>>> +		}
>>>>> +		priv->vdda = NULL;
>>>>> +	}
>>>>> +
>>>>> +	priv->vdd = devm_regulator_get_optional(&pdev->dev, "vdd");
>>>>> +	if (IS_ERR(priv->vdd)) {
>>>>> +		ret = PTR_ERR(priv->vdd);
>>>>> +		if (ret != -ENODEV) {
>>>>> +			if (ret != -EPROBE_DEFER)
>>>>> +				dev_err(&pdev->dev, "vdd get failed, %d\n",
>>>>> +					ret);
>>>>> +			return ret;
>>>>> +		}
>>>>> +		priv->vdd = NULL;
>>>>> +	}
>>>>> +
>>>>>  	priv->aclk = devm_clk_get(&pdev->dev, "adc");
>>>>>  	if (IS_ERR(priv->aclk)) {
>>>>>  		ret = PTR_ERR(priv->aclk);
>>>>> @@ -495,6 +716,13 @@ static int stm32_adc_probe(struct platform_device *pdev)
>>>>>  		priv->bclk = NULL;
>>>>>  	}
>>>>>  
>>>>> +	ret = stm32_adc_core_syscfg_probe(np, priv);
>>>>> +	if (ret) {
>>>>> +		if (ret != -EPROBE_DEFER)
>>>>> +			dev_err(&pdev->dev, "Can't probe syscfg: %d\n", ret);
>>>>> +		return ret;
>>>>> +	}
>>>>> +
>>>>>  	pm_runtime_get_noresume(dev);
>>>>>  	pm_runtime_set_active(dev);
>>>>>  	pm_runtime_set_autosuspend_delay(dev, STM32_ADC_CORE_SLEEP_DELAY_MS);
>>>>> @@ -595,7 +823,7 @@ static const struct stm32_adc_priv_cfg stm32h7_adc_priv_cfg = {
>>>>>  };
>>>>>  
>>>>>  static const struct stm32_adc_priv_cfg stm32mp1_adc_priv_cfg = {
>>>>> -	.regs = &stm32h7_adc_common_regs,
>>>>> +	.regs = &stm32mp1_adc_common_regs,
>>>>>  	.clk_sel = stm32h7_adc_clk_sel,
>>>>>  	.max_clk_rate_hz = 40000000,
>>>>>  };  
>>>>  
>