linux-kernel - [PATCH 04/10] iio: adc: stm32: add optional support for exti gpios

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Message-ID: <1477412722-24061-5-git-send-email-fabrice.gasnier@st.com>
Date:   Tue, 25 Oct 2016 18:25:16 +0200
From:   Fabrice Gasnier <fabrice.gasnier@...com>
To:     <linux-iio@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC:     <jic23@...nel.org>, <linux@...linux.org.uk>, <robh+dt@...nel.org>,
        <mark.rutland@....com>, <mcoquelin.stm32@...il.com>,
        <alexandre.torgue@...com>, <lars@...afoo.de>, <knaack.h@....de>,
        <pmeerw@...erw.net>, <fabrice.gasnier@...com>
Subject: [PATCH 04/10] iio: adc: stm32: add optional support for exti gpios

STM32 ADC may use EXTi signals routed internally as trigger source
for conversions. Configure them as interrupt to configure this path
in HW to adc.
Note: interrupt handler isn't required here, and corresponding interrupt
can be kept masked at exti controller level.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@...com>
---
 drivers/iio/adc/stm32/stm32-adc.c | 45 +++++++++++++++++++++++++++++++++++++++
 drivers/iio/adc/stm32/stm32-adc.h |  3 +++
 2 files changed, 48 insertions(+)

diff --git a/drivers/iio/adc/stm32/stm32-adc.c b/drivers/iio/adc/stm32/stm32-adc.c
index 25d0307..1a13450 100644
--- a/drivers/iio/adc/stm32/stm32-adc.c
+++ b/drivers/iio/adc/stm32/stm32-adc.c
@@ -482,6 +482,12 @@ static irqreturn_t stm32_adc_common_isr(int irq, void *data)
 	return ret;
 }
 
+static irqreturn_t stm32_adc_exti_handler(int irq, void *data)
+{
+	/* Exti handler should not be invoqued, and is not used */
+	return IRQ_HANDLED;
+}
+
 /**
  * stm32_adc_validate_trigger() - validate trigger for stm32 adc
  * @indio_dev: IIO device
@@ -1051,6 +1057,41 @@ static void stm32_adc_unregister(struct stm32_adc *adc)
 	}
 }
 
+static int stm32_adc_exti_probe(struct stm32_adc_common *common)
+{
+	int i, irq, ret;
+
+	common->gpios = devm_gpiod_get_array_optional(common->dev, NULL,
+						      GPIOD_IN);
+	if (!common->gpios)
+		return 0;
+
+	for (i = 0; i < common->gpios->ndescs; i++) {
+		irq = gpiod_to_irq(common->gpios->desc[i]);
+		if (irq < 0) {
+			dev_err(common->dev, "gpio %d to irq failed\n", i);
+			return irq;
+		}
+
+		ret = devm_request_irq(common->dev, irq, stm32_adc_exti_handler,
+				       0, dev_name(common->dev), common);
+		if (ret) {
+			dev_err(common->dev, "request IRQ %d failed\n", irq);
+			return ret;
+		}
+
+		/*
+		 * gpios are configured as interrupts, so exti trigger path is
+		 * configured in HW. But getting interrupts when starting
+		 * conversions is unused here, so mask it in on exti
+		 * controller by default.
+		 */
+		disable_irq(irq);
+	}
+
+	return 0;
+}
+
 int stm32_adc_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node, *child;
@@ -1131,6 +1172,10 @@ int stm32_adc_probe(struct platform_device *pdev)
 		goto err_clk_disable;
 	}
 
+	ret = stm32_adc_exti_probe(common);
+	if (ret)
+		goto err_clk_disable;
+
 	/* Parse adc child nodes to retrieve master/slave instances data */
 	for_each_available_child_of_node(np, child) {
 		ret = stm32_adc_register(common, child);
diff --git a/drivers/iio/adc/stm32/stm32-adc.h b/drivers/iio/adc/stm32/stm32-adc.h
index 01a0dda..fe3568b 100644
--- a/drivers/iio/adc/stm32/stm32-adc.h
+++ b/drivers/iio/adc/stm32/stm32-adc.h
@@ -23,6 +23,7 @@
 #define __STM32_ADC_H
 
 #include <linux/dmaengine.h>
+#include <linux/gpio/consumer.h>
 #include <linux/irq_work.h>
 
 /*
@@ -323,6 +324,7 @@ struct stm32_adc {
  * @aclk:		common clock for the analog circuitry
  * @vref:		regulator reference
  * @vref_mv:		vref voltage (mv)
+ * @gpio_descs:		gpio descriptor used to configure EXTi triggers
  * @lock:		mutex
  */
 struct stm32_adc_common {
@@ -335,6 +337,7 @@ struct stm32_adc_common {
 	struct clk			*aclk;
 	struct regulator		*vref;
 	int				vref_mv;
+	struct gpio_descs		*gpios;
 	struct mutex			lock;	/* read_raw lock */
 };
 
-- 
1.9.1