iio: adc: stm32-adc: move self-calibration to prepare routine

Move self-calibration routine to prepare routine.
- This is precursor patch to ease power management handling.
- This also allow to factorize few error cases (error handling).

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index 378411853d7516b1fc3121da560f9e1679583ed4..7980c46fe37c1ed1779214b9508f9de8043f01af 100644 (file)
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -199,11 +199,13 @@ struct stm32_adc_trig_info {
  * @calfact_s: Calibration offset for single ended channels
  * @calfact_d: Calibration offset in differential
  * @lincalfact: Linearity calibration factor
+ * @calibrated: Indicates calibration status
  */
 struct stm32_adc_calib {
        u32                     calfact_s;
        u32                     calfact_d;
        u32                     lincalfact[STM32H7_LINCALFACT_NUM];
+       bool                    calibrated;
 };
 
 /**
@@ -251,7 +253,6 @@ struct stm32_adc;
  * @trigs:             external trigger sources
  * @clk_required:      clock is required
  * @has_vregready:     vregready status flag presence
- * @selfcalib:         optional routine for self-calibration
  * @prepare:           optional prepare routine (power-up, enable)
  * @start_conv:                routine to start conversions
  * @stop_conv:         routine to stop conversions
@@ -264,7 +265,6 @@ struct stm32_adc_cfg {
        struct stm32_adc_trig_info      *trigs;
        bool clk_required;
        bool has_vregready;
-       int (*selfcalib)(struct stm32_adc *);
        int (*prepare)(struct stm32_adc *);
        void (*start_conv)(struct stm32_adc *, bool dma);
        void (*stop_conv)(struct stm32_adc *);
@@ -777,6 +777,7 @@ static void stm32h7_adc_disable(struct stm32_adc *adc)
 /**
  * stm32h7_adc_read_selfcalib() - read calibration shadow regs, save result
  * @adc: stm32 adc instance
+ * Note: Must be called once ADC is enabled, so LINCALRDYW[1..6] are writable
  */
 static int stm32h7_adc_read_selfcalib(struct stm32_adc *adc)
 {
@@ -784,11 +785,6 @@ static int stm32h7_adc_read_selfcalib(struct stm32_adc *adc)
        int i, ret;
        u32 lincalrdyw_mask, val;
 
-       /* Enable adc so LINCALRDYW1..6 bits are writable */
-       ret = stm32h7_adc_enable(adc);
-       if (ret)
-               return ret;
-
        /* Read linearity calibration */
        lincalrdyw_mask = STM32H7_LINCALRDYW6;
        for (i = STM32H7_LINCALFACT_NUM - 1; i >= 0; i--) {
@@ -801,7 +797,7 @@ static int stm32h7_adc_read_selfcalib(struct stm32_adc *adc)
                                                   100, STM32_ADC_TIMEOUT_US);
                if (ret) {
                        dev_err(&indio_dev->dev, "Failed to read calfact\n");
-                       goto disable;
+                       return ret;
                }
 
                val = stm32_adc_readl(adc, STM32H7_ADC_CALFACT2);
@@ -817,11 +813,9 @@ static int stm32h7_adc_read_selfcalib(struct stm32_adc *adc)
        adc->cal.calfact_s >>= STM32H7_CALFACT_S_SHIFT;
        adc->cal.calfact_d = (val & STM32H7_CALFACT_D_MASK);
        adc->cal.calfact_d >>= STM32H7_CALFACT_D_SHIFT;
+       adc->cal.calibrated = true;
 
-disable:
-       stm32h7_adc_disable(adc);
-
-       return ret;
+       return 0;
 }
 
 /**
@@ -898,9 +892,9 @@ static int stm32h7_adc_restore_selfcalib(struct stm32_adc *adc)
 #define STM32H7_ADC_CALIB_TIMEOUT_US           100000
 
 /**
- * stm32h7_adc_selfcalib() - Procedure to calibrate ADC (from power down)
+ * stm32h7_adc_selfcalib() - Procedure to calibrate ADC
  * @adc: stm32 adc instance
- * Exit from power down, calibrate ADC, then return to power down.
+ * Note: Must be called once ADC is out of power down.
  */
 static int stm32h7_adc_selfcalib(struct stm32_adc *adc)
 {
@@ -908,9 +902,8 @@ static int stm32h7_adc_selfcalib(struct stm32_adc *adc)
        int ret;
        u32 val;
 
-       ret = stm32h7_adc_exit_pwr_down(adc);
-       if (ret)
-               return ret;
+       if (adc->cal.calibrated)
+               return true;
 
        /*
         * Select calibration mode:
@@ -927,7 +920,7 @@ static int stm32h7_adc_selfcalib(struct stm32_adc *adc)
                                           STM32H7_ADC_CALIB_TIMEOUT_US);
        if (ret) {
                dev_err(&indio_dev->dev, "calibration failed\n");
-               goto pwr_dwn;
+               goto out;
        }
 
        /*
@@ -944,18 +937,13 @@ static int stm32h7_adc_selfcalib(struct stm32_adc *adc)
                                           STM32H7_ADC_CALIB_TIMEOUT_US);
        if (ret) {
                dev_err(&indio_dev->dev, "calibration failed\n");
-               goto pwr_dwn;
+               goto out;
        }
 
+out:
        stm32_adc_clr_bits(adc, STM32H7_ADC_CR,
                           STM32H7_ADCALDIF | STM32H7_ADCALLIN);
 
-       /* Read calibration result for future reference */
-       ret = stm32h7_adc_read_selfcalib(adc);
-
-pwr_dwn:
-       stm32h7_adc_enter_pwr_down(adc);
-
        return ret;
 }
 
@@ -972,19 +960,28 @@ pwr_dwn:
  */
 static int stm32h7_adc_prepare(struct stm32_adc *adc)
 {
-       int ret;
+       int calib, ret;
 
        ret = stm32h7_adc_exit_pwr_down(adc);
        if (ret)
                return ret;
 
+       ret = stm32h7_adc_selfcalib(adc);
+       if (ret < 0)
+               goto pwr_dwn;
+       calib = ret;
+
        stm32_adc_writel(adc, STM32H7_ADC_DIFSEL, adc->difsel);
 
        ret = stm32h7_adc_enable(adc);
        if (ret)
                goto pwr_dwn;
 
-       ret = stm32h7_adc_restore_selfcalib(adc);
+       /* Either restore or read calibration result for future reference */
+       if (calib)
+               ret = stm32h7_adc_restore_selfcalib(adc);
+       else
+               ret = stm32h7_adc_read_selfcalib(adc);
        if (ret)
                goto disable;
 
@@ -1880,12 +1877,6 @@ static int stm32_adc_probe(struct platform_device *pdev)
                goto err_clk_disable;
        stm32_adc_set_res(adc);
 
-       if (adc->cfg->selfcalib) {
-               ret = adc->cfg->selfcalib(adc);
-               if (ret)
-                       goto err_clk_disable;
-       }
-
        ret = stm32_adc_chan_of_init(indio_dev);
        if (ret < 0)
                goto err_clk_disable;
@@ -1961,7 +1952,6 @@ static const struct stm32_adc_cfg stm32h7_adc_cfg = {
        .regs = &stm32h7_adc_regspec,
        .adc_info = &stm32h7_adc_info,
        .trigs = stm32h7_adc_trigs,
-       .selfcalib = stm32h7_adc_selfcalib,
        .start_conv = stm32h7_adc_start_conv,
        .stop_conv = stm32h7_adc_stop_conv,
        .prepare = stm32h7_adc_prepare,
@@ -1974,7 +1964,6 @@ static const struct stm32_adc_cfg stm32mp1_adc_cfg = {
        .adc_info = &stm32h7_adc_info,
        .trigs = stm32h7_adc_trigs,
        .has_vregready = true,
-       .selfcalib = stm32h7_adc_selfcalib,
        .start_conv = stm32h7_adc_start_conv,
        .stop_conv = stm32h7_adc_stop_conv,
        .prepare = stm32h7_adc_prepare,