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From:   Alexandru Ardelean <alexandru.ardelean@analog.com>
To:     <linux-iio@vger.kernel.org>,
        <linux-stm32@st-md-mailman.stormreply.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>
CC:     <jic23@kernel.org>, <mcoquelin.stm32@gmail.com>,
        <alexandre.torgue@st.com>, <olivier.moysan@st.com>,
        <fabrice.gasnier@st.com>,
        Alexandru Ardelean <alexandru.ardelean@analog.com>
Subject: [PATCH v3] iio: stm32-adc:  remove usage of iio_priv_to_dev() helper
Date:   Tue, 26 May 2020 16:44:48 +0300
Message-ID: <20200526134448.7328-1-alexandru.ardelean@analog.com>
In-Reply-To: <20200525090720.72696-1-alexandru.ardelean@analog.com>
References: <20200525090720.72696-1-alexandru.ardelean@analog.com>
MIME-Version: 1.0
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

We may want to get rid of the iio_priv_to_dev() helper. The reason is that
we will hide some of the members of the iio_dev structure (to prevent
drivers from accessing them directly), and that will also mean hiding the
implementation of the iio_priv_to_dev() helper inside the IIO core.

Hiding the implementation of iio_priv_to_dev() implies that some fast-paths
may not be fast anymore, so a general idea is to try to get rid of the
iio_priv_to_dev() altogether.
The iio_priv() helper won't be affected by the rework, as the iio_dev
struct will keep a reference to the private information.

For this driver, not using iio_priv_to_dev(), means reworking some paths to
pass the iio device and using iio_priv() to access the private information.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
---

Changelog v2 -> v3:
- update doc-strings; warnings show-up during build with W=1 arg

Changelog v1 -> v2:
- converted to pass reference to IIO device in function hooks (vs
  reference
  to adc private data)

 drivers/iio/adc/stm32-adc.c | 118 +++++++++++++++++++-----------------
 1 file changed, 63 insertions(+), 55 deletions(-)

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index ae622ee6d08c..1dd97ec5571c 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -162,10 +162,10 @@ struct stm32_adc_cfg {
 	struct stm32_adc_trig_info	*trigs;
 	bool clk_required;
 	bool has_vregready;
-	int (*prepare)(struct stm32_adc *);
-	void (*start_conv)(struct stm32_adc *, bool dma);
-	void (*stop_conv)(struct stm32_adc *);
-	void (*unprepare)(struct stm32_adc *);
+	int (*prepare)(struct iio_dev *);
+	void (*start_conv)(struct iio_dev *, bool dma);
+	void (*stop_conv)(struct iio_dev *);
+	void (*unprepare)(struct iio_dev *);
 	const unsigned int *smp_cycles;
 };
 
@@ -538,10 +538,11 @@ static void stm32_adc_set_res(struct stm32_adc *adc)
 
 static int stm32_adc_hw_stop(struct device *dev)
 {
-	struct stm32_adc *adc = dev_get_drvdata(dev);
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct stm32_adc *adc = iio_priv(indio_dev);
 
 	if (adc->cfg->unprepare)
-		adc->cfg->unprepare(adc);
+		adc->cfg->unprepare(indio_dev);
 
 	if (adc->clk)
 		clk_disable_unprepare(adc->clk);
@@ -551,7 +552,8 @@ static int stm32_adc_hw_stop(struct device *dev)
 
 static int stm32_adc_hw_start(struct device *dev)
 {
-	struct stm32_adc *adc = dev_get_drvdata(dev);
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct stm32_adc *adc = iio_priv(indio_dev);
 	int ret;
 
 	if (adc->clk) {
@@ -563,7 +565,7 @@ static int stm32_adc_hw_start(struct device *dev)
 	stm32_adc_set_res(adc);
 
 	if (adc->cfg->prepare) {
-		ret = adc->cfg->prepare(adc);
+		ret = adc->cfg->prepare(indio_dev);
 		if (ret)
 			goto err_clk_dis;
 	}
@@ -579,7 +581,7 @@ static int stm32_adc_hw_start(struct device *dev)
 
 /**
  * stm32f4_adc_start_conv() - Start conversions for regular channels.
- * @adc: stm32 adc instance
+ * @indio_dev: IIO device instance
  * @dma: use dma to transfer conversion result
  *
  * Start conversions for regular channels.
@@ -587,8 +589,10 @@ static int stm32_adc_hw_start(struct device *dev)
  * conversions, in IIO buffer modes. Otherwise, use ADC interrupt with direct
  * DR read instead (e.g. read_raw, or triggered buffer mode without DMA).
  */
-static void stm32f4_adc_start_conv(struct stm32_adc *adc, bool dma)
+static void stm32f4_adc_start_conv(struct iio_dev *indio_dev, bool dma)
 {
+	struct stm32_adc *adc = iio_priv(indio_dev);
+
 	stm32_adc_set_bits(adc, STM32F4_ADC_CR1, STM32F4_SCAN);
 
 	if (dma)
@@ -605,8 +609,10 @@ static void stm32f4_adc_start_conv(struct stm32_adc *adc, bool dma)
 		stm32_adc_set_bits(adc, STM32F4_ADC_CR2, STM32F4_SWSTART);
 }
 
-static void stm32f4_adc_stop_conv(struct stm32_adc *adc)
+static void stm32f4_adc_stop_conv(struct iio_dev *indio_dev)
 {
+	struct stm32_adc *adc = iio_priv(indio_dev);
+
 	stm32_adc_clr_bits(adc, STM32F4_ADC_CR2, STM32F4_EXTEN_MASK);
 	stm32_adc_clr_bits(adc, STM32F4_ADC_SR, STM32F4_STRT);
 
@@ -615,8 +621,9 @@ static void stm32f4_adc_stop_conv(struct stm32_adc *adc)
 			   STM32F4_ADON | STM32F4_DMA | STM32F4_DDS);
 }
 
-static void stm32h7_adc_start_conv(struct stm32_adc *adc, bool dma)
+static void stm32h7_adc_start_conv(struct iio_dev *indio_dev, bool dma)
 {
+	struct stm32_adc *adc = iio_priv(indio_dev);
 	enum stm32h7_adc_dmngt dmngt;
 	unsigned long flags;
 	u32 val;
@@ -635,9 +642,9 @@ static void stm32h7_adc_start_conv(struct stm32_adc *adc, bool dma)
 	stm32_adc_set_bits(adc, STM32H7_ADC_CR, STM32H7_ADSTART);
 }
 
-static void stm32h7_adc_stop_conv(struct stm32_adc *adc)
+static void stm32h7_adc_stop_conv(struct iio_dev *indio_dev)
 {
-	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+	struct stm32_adc *adc = iio_priv(indio_dev);
 	int ret;
 	u32 val;
 
@@ -652,9 +659,9 @@ static void stm32h7_adc_stop_conv(struct stm32_adc *adc)
 	stm32_adc_clr_bits(adc, STM32H7_ADC_CFGR, STM32H7_DMNGT_MASK);
 }
 
-static int stm32h7_adc_exit_pwr_down(struct stm32_adc *adc)
+static int stm32h7_adc_exit_pwr_down(struct iio_dev *indio_dev)
 {
-	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+	struct stm32_adc *adc = iio_priv(indio_dev);
 	int ret;
 	u32 val;
 
@@ -690,9 +697,9 @@ static void stm32h7_adc_enter_pwr_down(struct stm32_adc *adc)
 	stm32_adc_set_bits(adc, STM32H7_ADC_CR, STM32H7_DEEPPWD);
 }
 
-static int stm32h7_adc_enable(struct stm32_adc *adc)
+static int stm32h7_adc_enable(struct iio_dev *indio_dev)
 {
-	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+	struct stm32_adc *adc = iio_priv(indio_dev);
 	int ret;
 	u32 val;
 
@@ -713,9 +720,9 @@ static int stm32h7_adc_enable(struct stm32_adc *adc)
 	return ret;
 }
 
-static void stm32h7_adc_disable(struct stm32_adc *adc)
+static void stm32h7_adc_disable(struct iio_dev *indio_dev)
 {
-	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+	struct stm32_adc *adc = iio_priv(indio_dev);
 	int ret;
 	u32 val;
 
@@ -730,12 +737,12 @@ static void stm32h7_adc_disable(struct stm32_adc *adc)
 
 /**
  * stm32h7_adc_read_selfcalib() - read calibration shadow regs, save result
- * @adc: stm32 adc instance
+ * @indio_dev: IIO device 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)
+static int stm32h7_adc_read_selfcalib(struct iio_dev *indio_dev)
 {
-	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+	struct stm32_adc *adc = iio_priv(indio_dev);
 	int i, ret;
 	u32 lincalrdyw_mask, val;
 
@@ -774,12 +781,12 @@ static int stm32h7_adc_read_selfcalib(struct stm32_adc *adc)
 
 /**
  * stm32h7_adc_restore_selfcalib() - Restore saved self-calibration result
- * @adc: stm32 adc instance
+ * @indio_dev: IIO device instance
  * Note: ADC must be enabled, with no on-going conversions.
  */
-static int stm32h7_adc_restore_selfcalib(struct stm32_adc *adc)
+static int stm32h7_adc_restore_selfcalib(struct iio_dev *indio_dev)
 {
-	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+	struct stm32_adc *adc = iio_priv(indio_dev);
 	int i, ret;
 	u32 lincalrdyw_mask, val;
 
@@ -847,12 +854,12 @@ static int stm32h7_adc_restore_selfcalib(struct stm32_adc *adc)
 
 /**
  * stm32h7_adc_selfcalib() - Procedure to calibrate ADC
- * @adc: stm32 adc instance
+ * @indio_dev: IIO device instance
  * Note: Must be called once ADC is out of power down.
  */
-static int stm32h7_adc_selfcalib(struct stm32_adc *adc)
+static int stm32h7_adc_selfcalib(struct iio_dev *indio_dev)
 {
-	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+	struct stm32_adc *adc = iio_priv(indio_dev);
 	int ret;
 	u32 val;
 
@@ -903,7 +910,7 @@ static int stm32h7_adc_selfcalib(struct stm32_adc *adc)
 
 /**
  * stm32h7_adc_prepare() - Leave power down mode to enable ADC.
- * @adc: stm32 adc instance
+ * @indio_dev: IIO device instance
  * Leave power down mode.
  * Configure channels as single ended or differential before enabling ADC.
  * Enable ADC.
@@ -912,30 +919,31 @@ static int stm32h7_adc_selfcalib(struct stm32_adc *adc)
  * - Only one input is selected for single ended (e.g. 'vinp')
  * - Two inputs are selected for differential channels (e.g. 'vinp' & 'vinn')
  */
-static int stm32h7_adc_prepare(struct stm32_adc *adc)
+static int stm32h7_adc_prepare(struct iio_dev *indio_dev)
 {
+	struct stm32_adc *adc = iio_priv(indio_dev);
 	int calib, ret;
 
-	ret = stm32h7_adc_exit_pwr_down(adc);
+	ret = stm32h7_adc_exit_pwr_down(indio_dev);
 	if (ret)
 		return ret;
 
-	ret = stm32h7_adc_selfcalib(adc);
+	ret = stm32h7_adc_selfcalib(indio_dev);
 	if (ret < 0)
 		goto pwr_dwn;
 	calib = ret;
 
 	stm32_adc_writel(adc, STM32H7_ADC_DIFSEL, adc->difsel);
 
-	ret = stm32h7_adc_enable(adc);
+	ret = stm32h7_adc_enable(indio_dev);
 	if (ret)
 		goto pwr_dwn;
 
 	/* Either restore or read calibration result for future reference */
 	if (calib)
-		ret = stm32h7_adc_restore_selfcalib(adc);
+		ret = stm32h7_adc_restore_selfcalib(indio_dev);
 	else
-		ret = stm32h7_adc_read_selfcalib(adc);
+		ret = stm32h7_adc_read_selfcalib(indio_dev);
 	if (ret)
 		goto disable;
 
@@ -944,16 +952,18 @@ static int stm32h7_adc_prepare(struct stm32_adc *adc)
 	return 0;
 
 disable:
-	stm32h7_adc_disable(adc);
+	stm32h7_adc_disable(indio_dev);
 pwr_dwn:
 	stm32h7_adc_enter_pwr_down(adc);
 
 	return ret;
 }
 
-static void stm32h7_adc_unprepare(struct stm32_adc *adc)
+static void stm32h7_adc_unprepare(struct iio_dev *indio_dev)
 {
-	stm32h7_adc_disable(adc);
+	struct stm32_adc *adc = iio_priv(indio_dev);
+
+	stm32h7_adc_disable(indio_dev);
 	stm32h7_adc_enter_pwr_down(adc);
 }
 
@@ -1160,7 +1170,7 @@ static int stm32_adc_single_conv(struct iio_dev *indio_dev,
 
 	stm32_adc_conv_irq_enable(adc);
 
-	adc->cfg->start_conv(adc, false);
+	adc->cfg->start_conv(indio_dev, false);
 
 	timeout = wait_for_completion_interruptible_timeout(
 					&adc->completion, STM32_ADC_TIMEOUT);
@@ -1173,7 +1183,7 @@ static int stm32_adc_single_conv(struct iio_dev *indio_dev,
 		ret = IIO_VAL_INT;
 	}
 
-	adc->cfg->stop_conv(adc);
+	adc->cfg->stop_conv(indio_dev);
 
 	stm32_adc_conv_irq_disable(adc);
 
@@ -1227,8 +1237,8 @@ static int stm32_adc_read_raw(struct iio_dev *indio_dev,
 
 static irqreturn_t stm32_adc_threaded_isr(int irq, void *data)
 {
-	struct stm32_adc *adc = data;
-	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+	struct iio_dev *indio_dev = data;
+	struct stm32_adc *adc = iio_priv(indio_dev);
 	const struct stm32_adc_regspec *regs = adc->cfg->regs;
 	u32 status = stm32_adc_readl(adc, regs->isr_eoc.reg);
 
@@ -1240,8 +1250,8 @@ static irqreturn_t stm32_adc_threaded_isr(int irq, void *data)
 
 static irqreturn_t stm32_adc_isr(int irq, void *data)
 {
-	struct stm32_adc *adc = data;
-	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+	struct iio_dev *indio_dev = data;
+	struct stm32_adc *adc = iio_priv(indio_dev);
 	const struct stm32_adc_regspec *regs = adc->cfg->regs;
 	u32 status = stm32_adc_readl(adc, regs->isr_eoc.reg);
 
@@ -1514,7 +1524,7 @@ static int __stm32_adc_buffer_postenable(struct iio_dev *indio_dev)
 	if (!adc->dma_chan)
 		stm32_adc_conv_irq_enable(adc);
 
-	adc->cfg->start_conv(adc, !!adc->dma_chan);
+	adc->cfg->start_conv(indio_dev, !!adc->dma_chan);
 
 	return 0;
 
@@ -1547,7 +1557,7 @@ static void __stm32_adc_buffer_predisable(struct iio_dev *indio_dev)
 	struct stm32_adc *adc = iio_priv(indio_dev);
 	struct device *dev = indio_dev->dev.parent;
 
-	adc->cfg->stop_conv(adc);
+	adc->cfg->stop_conv(indio_dev);
 	if (!adc->dma_chan)
 		stm32_adc_conv_irq_disable(adc);
 
@@ -1891,7 +1901,7 @@ static int stm32_adc_probe(struct platform_device *pdev)
 	indio_dev->info = &stm32_adc_iio_info;
 	indio_dev->modes = INDIO_DIRECT_MODE | INDIO_HARDWARE_TRIGGERED;
 
-	platform_set_drvdata(pdev, adc);
+	platform_set_drvdata(pdev, indio_dev);
 
 	ret = of_property_read_u32(pdev->dev.of_node, "reg", &adc->offset);
 	if (ret != 0) {
@@ -1905,7 +1915,7 @@ static int stm32_adc_probe(struct platform_device *pdev)
 
 	ret = devm_request_threaded_irq(&pdev->dev, adc->irq, stm32_adc_isr,
 					stm32_adc_threaded_isr,
-					0, pdev->name, adc);
+					0, pdev->name, indio_dev);
 	if (ret) {
 		dev_err(&pdev->dev, "failed to request IRQ\n");
 		return ret;
@@ -1989,8 +1999,8 @@ static int stm32_adc_probe(struct platform_device *pdev)
 
 static int stm32_adc_remove(struct platform_device *pdev)
 {
-	struct stm32_adc *adc = platform_get_drvdata(pdev);
-	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct stm32_adc *adc = iio_priv(indio_dev);
 
 	pm_runtime_get_sync(&pdev->dev);
 	iio_device_unregister(indio_dev);
@@ -2012,8 +2022,7 @@ static int stm32_adc_remove(struct platform_device *pdev)
 #if defined(CONFIG_PM_SLEEP)
 static int stm32_adc_suspend(struct device *dev)
 {
-	struct stm32_adc *adc = dev_get_drvdata(dev);
-	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 
 	if (iio_buffer_enabled(indio_dev))
 		__stm32_adc_buffer_predisable(indio_dev);
@@ -2023,8 +2032,7 @@ static int stm32_adc_suspend(struct device *dev)
 
 static int stm32_adc_resume(struct device *dev)
 {
-	struct stm32_adc *adc = dev_get_drvdata(dev);
-	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
 	int ret;
 
 	ret = pm_runtime_force_resume(dev);
-- 
2.17.1