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SubjectRe: [PATCH 2/3] iio: adc: stm32-adc: add analog switches supply control
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 =


> + .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?

> + 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,
> };

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