[PATCH v7 0/6] iio: proximity: Add interrupt support for RFD77402

[PATCH v7 0/6] iio: proximity: Add interrupt support for RFD77402

[Shrikant Raskar via B4 Relay]

This series improves the RFD77402 ToF driver by cleaning up include
ordering, improving resource lifetime handling, switching to kernel
polling helpers, and adding optional interrupt-driven operation.

Changes in v7:
- Add new patch to align polling timeout with datasheet.
- Rename the polled value variable in rfd77402_wait_for_result().
- Fix read_poll_timeout() condition.
- Update commit message for devm_mutex_init() patch.
- Update commit message for 'Use kernel helper for result polling'
  patch.

Signed-off-by: Shrikant Raskar <raskar.shree97@gmail.com>
---
Changelog:

v5 to v6:
- Convert rfd77402_data comments to proper kernel-doc format.
- Re-order the patch sequence as suggested.
- Add missing header files.
- Refactor code to get rid of the i2c_set_clientdata() and
respective getter calls.
Link to v6:
https://lore.kernel.org/r/20260121-b4-rfd77402_v5-v6-0-5b944d0605dd@gmail.com/

v4 to v5:
- Add precursor patch to reorder includes before functional changes.
- Use devm_mutex_init() for proper lifetime management.
- Address maintainer feedback on polling helper usage.
- Remove dead code from interrupt_handler.
- Add blank line in rfd77402_wait_for_irq.
- Update measurement timeout comment.
- Add helper function for result polling.
- Fix comment format in rfd77402_init.
- Remove 'data->irq_en = false', as it already initialized by kzalloc.
- Improve documentation of private driver data.
Link to v4: https://lore.kernel.org/all/20260101-b4-rfd77402_irq-v4-0-42cd54359e9f@gmail.com/

v3 to v4:
- No code change.
Link to v3: https://lore.kernel.org/all/20251221083902.134098-1-raskar.shree97@gmail.com/

v2 to v3:
- Add 'Reviewed-by' tag to dt-binding patch.
- Update commit message in OF device ID patch.
- Update commit message in the third patch.
- Replace rfd77402_result_polling() with read_poll_timeout().
- Add 'struct rfd77402_data' details in kernel-doc format.
- Arrange includes in order.
- Add comment for completion timeout value.
- Remove blank lines.
- Indent the comments to code.
- Convert mutex_init() to devm_mutex_init().
- Remove 'IRQF_TRIGGER_FALLING' flag from devm_request_threaded_irq().
- Drop the duplicate message.
- Replace 'dev_info' with 'dev_dbg()'.
- Update 'dev_id' to 'pdata' in rfd77402_interrupt_handler().
- Drop 'interrupt mode' comment
- Use 'if(ret)' instead of 'if(ret < 0) for consistency.
- Use 'return i2c_smbus_write_byte_data()' in 'rfd77402_config_irq'.
Link to v2: https://lore.kernel.org/all/20251130153712.6792-1-raskar.shree97@gmail.com/

v1 to v2:
- Fix commit message for dt-binding patch
- Update interrupt description in dt-binding
- Add 'vdd-supply' to 'required' property in dt-binding
- Add patch for moving polling implementation to helper
- Add helper rfd77402_wait_for_irq()
- Code refactoring
- Return failure if request IRQ fail
Link to v1: https://lore.kernel.org/all/20251126031440.30065-1-raskar.shree97@gmail.com/

---
Shrikant Raskar (6):
      iio: proximity: rfd77402: Reorder header includes
      iio: proximity: rfd77402: Align polling timeout with datasheet
      iio: proximity: rfd77402: Use kernel helper for result polling
      iio: proximity: rfd77402: Use devm-managed mutex initialization
      iio: proximity: rfd77402: Document device private data structure
      iio: proximity: rfd77402: Add interrupt handling support

 drivers/iio/proximity/rfd77402.c | 174 +++++++++++++++++++++++++++++++++------
 1 file changed, 147 insertions(+), 27 deletions(-)
---
base-commit: 0f61b1860cc3f52aef9036d7235ed1f017632193
change-id: 20260121-b4-rfd77402_v5-558b8e28c387

Best regards,
-- 
Shrikant Raskar <raskar.shree97@gmail.com>

[PATCH v7 1/6] iio: proximity: rfd77402: Reorder header includes

[Shrikant Raskar via B4 Relay]

From: Shrikant Raskar <raskar.shree97@gmail.com>

Reorder header includes to follow kernel include
ordering conventions.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Shrikant Raskar <raskar.shree97@gmail.com>
---
 drivers/iio/proximity/rfd77402.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/proximity/rfd77402.c b/drivers/iio/proximity/rfd77402.c
index aff60a3c1a6f..69cc1505b964 100644
--- a/drivers/iio/proximity/rfd77402.c
+++ b/drivers/iio/proximity/rfd77402.c
@@ -10,9 +10,9 @@
  * https://media.digikey.com/pdf/Data%20Sheets/RF%20Digital%20PDFs/RFD77402.pdf
  */
 
-#include <linux/module.h>
-#include <linux/i2c.h>
 #include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
 
 #include <linux/iio/iio.h>
 

-- 
2.43.0

[PATCH v7 2/6] iio: proximity: rfd77402: Align polling timeout with datasheet

[Shrikant Raskar via B4 Relay]

From: Shrikant Raskar <raskar.shree97@gmail.com>

Update the polling delay to use a 100 ms timeout, as specified
in the RFD77402 datasheet.

Signed-off-by: Shrikant Raskar <raskar.shree97@gmail.com>
---
 drivers/iio/proximity/rfd77402.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iio/proximity/rfd77402.c b/drivers/iio/proximity/rfd77402.c
index 69cc1505b964..3e14660a4bb1 100644
--- a/drivers/iio/proximity/rfd77402.c
+++ b/drivers/iio/proximity/rfd77402.c
@@ -132,7 +132,7 @@ static int rfd77402_measure(struct i2c_client *client)
 			goto err;
 		if (ret & RFD77402_ICSR_RESULT)
 			break;
-		msleep(20);
+		msleep(10);
 	}
 
 	if (tries < 0) {

-- 
2.43.0

[PATCH v7 3/6] iio: proximity: rfd77402: Use kernel helper for result polling

[Shrikant Raskar via B4 Relay]

From: Shrikant Raskar <raskar.shree97@gmail.com>

Replace the manually written polling loop with read_poll_timeout(),
the kernel's standard helper for waiting on hardware status.This
makes the code easier to read.

Move the polling logic into a dedicated helper function, as it will
be reused by future updates.

Signed-off-by: Shrikant Raskar <raskar.shree97@gmail.com>
---
 drivers/iio/proximity/rfd77402.c | 38 +++++++++++++++++++++++---------------
 1 file changed, 23 insertions(+), 15 deletions(-)

diff --git a/drivers/iio/proximity/rfd77402.c b/drivers/iio/proximity/rfd77402.c
index 3e14660a4bb1..6b23fb3bfe1d 100644
--- a/drivers/iio/proximity/rfd77402.c
+++ b/drivers/iio/proximity/rfd77402.c
@@ -12,6 +12,7 @@
 
 #include <linux/delay.h>
 #include <linux/i2c.h>
+#include <linux/iopoll.h>
 #include <linux/module.h>
 
 #include <linux/iio/iio.h>
@@ -110,10 +111,27 @@ static int rfd77402_set_state(struct i2c_client *client, u8 state, u16 check)
 	return 0;
 }
 
-static int rfd77402_measure(struct i2c_client *client)
+static int rfd77402_wait_for_result(struct rfd77402_data *data)
 {
+	struct i2c_client *client = data->client;
+	int val, ret;
+
+	ret = read_poll_timeout(i2c_smbus_read_byte_data, val,
+				 (val < 0) || (val & RFD77402_ICSR_RESULT),
+				 10 * USEC_PER_MSEC,
+				 10 * 10 * USEC_PER_MSEC,
+				 false,
+				 client, RFD77402_ICSR);
+	if (val < 0)
+		return val;
+
+	return ret;
+}
+
+static int rfd77402_measure(struct rfd77402_data *data)
+{
+	struct i2c_client *client = data->client;
 	int ret;
-	int tries = 10;
 
 	ret = rfd77402_set_state(client, RFD77402_CMD_MCPU_ON,
 				 RFD77402_STATUS_MCPU_ON);
@@ -126,19 +144,9 @@ static int rfd77402_measure(struct i2c_client *client)
 	if (ret < 0)
 		goto err;
 
-	while (tries-- > 0) {
-		ret = i2c_smbus_read_byte_data(client, RFD77402_ICSR);
-		if (ret < 0)
-			goto err;
-		if (ret & RFD77402_ICSR_RESULT)
-			break;
-		msleep(10);
-	}
-
-	if (tries < 0) {
-		ret = -ETIMEDOUT;
+	ret = rfd77402_wait_for_result(data);
+	if (ret < 0)
 		goto err;
-	}
 
 	ret = i2c_smbus_read_word_data(client, RFD77402_RESULT_R);
 	if (ret < 0)
@@ -168,7 +176,7 @@ static int rfd77402_read_raw(struct iio_dev *indio_dev,
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		mutex_lock(&data->lock);
-		ret = rfd77402_measure(data->client);
+		ret = rfd77402_measure(data);
 		mutex_unlock(&data->lock);
 		if (ret < 0)
 			return ret;

-- 
2.43.0

[PATCH v7 4/6] iio: proximity: rfd77402: Use devm-managed mutex initialization

[Shrikant Raskar via B4 Relay]

From: Shrikant Raskar <raskar.shree97@gmail.com>

Use devm_mutex_init() to tie the mutex lifetime to the device and
improve debugging when CONFIG_DEBUG_MUTEXES is enabled.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Shrikant Raskar <raskar.shree97@gmail.com>
---
 drivers/iio/proximity/rfd77402.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/proximity/rfd77402.c b/drivers/iio/proximity/rfd77402.c
index 6b23fb3bfe1d..a374a7389c33 100644
--- a/drivers/iio/proximity/rfd77402.c
+++ b/drivers/iio/proximity/rfd77402.c
@@ -283,7 +283,10 @@ static int rfd77402_probe(struct i2c_client *client)
 
 	data = iio_priv(indio_dev);
 	data->client = client;
-	mutex_init(&data->lock);
+
+	ret = devm_mutex_init(&client->dev, &data->lock);
+	if (ret)
+		return ret;
 
 	indio_dev->info = &rfd77402_info;
 	indio_dev->channels = rfd77402_channels;

-- 
2.43.0

[PATCH v7 5/6] iio: proximity: rfd77402: Document device private data structure

[Shrikant Raskar via B4 Relay]

From: Shrikant Raskar <raskar.shree97@gmail.com>

Add kernel-doc style comments for struct rfd77402_data to describe
the purpose of each member.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Shrikant Raskar <raskar.shree97@gmail.com>
---
 drivers/iio/proximity/rfd77402.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/proximity/rfd77402.c b/drivers/iio/proximity/rfd77402.c
index a374a7389c33..c29ae9af4a90 100644
--- a/drivers/iio/proximity/rfd77402.c
+++ b/drivers/iio/proximity/rfd77402.c
@@ -77,9 +77,13 @@ static const struct {
 	{RFD77402_HFCFG_3,	0x45d4},
 };
 
+/**
+ * struct rfd77402_data - device-specific data for the RFD77402 sensor
+ * @client: I2C client handle
+ * @lock: mutex to serialize sensor reads
+ */
 struct rfd77402_data {
 	struct i2c_client *client;
-	/* Serialize reads from the sensor */
 	struct mutex lock;
 };
 

-- 
2.43.0

[PATCH v7 6/6] iio: proximity: rfd77402: Add interrupt handling support

[Shrikant Raskar via B4 Relay]

From: Shrikant Raskar <raskar.shree97@gmail.com>

Add interrupt handling support to enable event-driven data acquisition
instead of continuous polling. This improves responsiveness, reduces
CPU overhead, and supports low-power operation by allowing the system
to remain idle until an interrupt occurs.

Signed-off-by: Shrikant Raskar <raskar.shree97@gmail.com>
---
 drivers/iio/proximity/rfd77402.c | 121 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 113 insertions(+), 8 deletions(-)

diff --git a/drivers/iio/proximity/rfd77402.c b/drivers/iio/proximity/rfd77402.c
index c29ae9af4a90..53dff934d66d 100644
--- a/drivers/iio/proximity/rfd77402.c
+++ b/drivers/iio/proximity/rfd77402.c
@@ -6,20 +6,28 @@
  *
  * 7-bit I2C slave address 0x4c
  *
- * TODO: interrupt
  * https://media.digikey.com/pdf/Data%20Sheets/RF%20Digital%20PDFs/RFD77402.pdf
  */
 
+#include <linux/bits.h>
+#include <linux/completion.h>
 #include <linux/delay.h>
+#include <linux/dev_printk.h>
+#include <linux/errno.h>
 #include <linux/i2c.h>
+#include <linux/interrupt.h>
 #include <linux/iopoll.h>
+#include <linux/jiffies.h>
 #include <linux/module.h>
+#include <linux/types.h>
 
 #include <linux/iio/iio.h>
 
 #define RFD77402_DRV_NAME "rfd77402"
 
 #define RFD77402_ICSR		0x00 /* Interrupt Control Status Register */
+#define RFD77402_ICSR_CLR_CFG   BIT(0)
+#define RFD77402_ICSR_CLR_TYPE  BIT(1)
 #define RFD77402_ICSR_INT_MODE	BIT(2)
 #define RFD77402_ICSR_INT_POL	BIT(3)
 #define RFD77402_ICSR_RESULT	BIT(4)
@@ -27,6 +35,12 @@
 #define RFD77402_ICSR_H2M_MSG	BIT(6)
 #define RFD77402_ICSR_RESET	BIT(7)
 
+#define RFD77402_IER		0x02
+#define RFD77402_IER_RESULT	BIT(0)
+#define RFD77402_IER_M2H_MSG	BIT(1)
+#define RFD77402_IER_H2M_MSG	BIT(2)
+#define RFD77402_IER_RESET	BIT(3)
+
 #define RFD77402_CMD_R		0x04
 #define RFD77402_CMD_SINGLE	0x01
 #define RFD77402_CMD_STANDBY	0x10
@@ -81,10 +95,14 @@ static const struct {
  * struct rfd77402_data - device-specific data for the RFD77402 sensor
  * @client: I2C client handle
  * @lock: mutex to serialize sensor reads
+ * @completion: completion used for interrupt-driven measurements
+ * @irq_en: indicates whether interrupt mode is enabled
  */
 struct rfd77402_data {
 	struct i2c_client *client;
 	struct mutex lock;
+	struct completion completion;
+	bool irq_en;
 };
 
 static const struct iio_chan_spec rfd77402_channels[] = {
@@ -95,6 +113,41 @@ static const struct iio_chan_spec rfd77402_channels[] = {
 	},
 };
 
+static irqreturn_t rfd77402_interrupt_handler(int irq, void *pdata)
+{
+	struct rfd77402_data *data = pdata;
+	int ret;
+
+	ret = i2c_smbus_read_byte_data(data->client, RFD77402_ICSR);
+	if (ret < 0)
+		return IRQ_NONE;
+
+	/* Check if the interrupt is from our device */
+	if (!(ret & RFD77402_ICSR_RESULT))
+		return IRQ_NONE;
+
+	/* Signal completion of measurement */
+	complete(&data->completion);
+	return IRQ_HANDLED;
+}
+
+static int rfd77402_wait_for_irq(struct rfd77402_data *data)
+{
+	int ret;
+
+	/*
+	 * According to RFD77402 Datasheet v1.8,
+	 * Section 3.1.1 "Single Measure" (Figure: Single Measure Flow Chart),
+	 * the suggested timeout for single measure is 100 ms.
+	 */
+	ret = wait_for_completion_timeout(&data->completion,
+					  msecs_to_jiffies(100));
+	if (ret == 0)
+		return -ETIMEDOUT;
+
+	return 0;
+}
+
 static int rfd77402_set_state(struct i2c_client *client, u8 state, u16 check)
 {
 	int ret;
@@ -120,6 +173,11 @@ static int rfd77402_wait_for_result(struct rfd77402_data *data)
 	struct i2c_client *client = data->client;
 	int val, ret;
 
+	if (data->irq_en) {
+		reinit_completion(&data->completion);
+		return rfd77402_wait_for_irq(data);
+	}
+
 	ret = read_poll_timeout(i2c_smbus_read_byte_data, val,
 				 (val < 0) || (val & RFD77402_ICSR_RESULT),
 				 10 * USEC_PER_MSEC,
@@ -200,8 +258,20 @@ static const struct iio_info rfd77402_info = {
 	.read_raw = rfd77402_read_raw,
 };
 
-static int rfd77402_init(struct i2c_client *client)
+static int rfd77402_config_irq(struct i2c_client *client, u8 csr, u8 ier)
 {
+	int ret;
+
+	ret = i2c_smbus_write_byte_data(client, RFD77402_ICSR, csr);
+	if (ret)
+		return ret;
+
+	return i2c_smbus_write_byte_data(client, RFD77402_IER, ier);
+}
+
+static int rfd77402_init(struct rfd77402_data *data)
+{
+	struct i2c_client *client = data->client;
 	int ret, i;
 
 	ret = rfd77402_set_state(client, RFD77402_CMD_STANDBY,
@@ -209,10 +279,26 @@ static int rfd77402_init(struct i2c_client *client)
 	if (ret < 0)
 		return ret;
 
-	/* configure INT pad as push-pull, active low */
-	ret = i2c_smbus_write_byte_data(client, RFD77402_ICSR,
-					RFD77402_ICSR_INT_MODE);
-	if (ret < 0)
+	if (data->irq_en) {
+		/*
+		 * Enable interrupt mode:
+		 * - Configure ICSR for auto-clear on read and
+		 *   push-pull output
+		 * - Enable "result ready" interrupt in IER
+		 */
+		ret = rfd77402_config_irq(client,
+					  RFD77402_ICSR_CLR_CFG |
+					  RFD77402_ICSR_INT_MODE,
+					  RFD77402_IER_RESULT);
+	} else {
+		/*
+		 * Disable all interrupts:
+		 * - Clear ICSR configuration
+		 * - Disable all interrupts in IER
+		 */
+		ret = rfd77402_config_irq(client, 0, 0);
+	}
+	if (ret)
 		return ret;
 
 	/* I2C configuration */
@@ -292,13 +378,29 @@ static int rfd77402_probe(struct i2c_client *client)
 	if (ret)
 		return ret;
 
+	init_completion(&data->completion);
+
+	if (client->irq > 0) {
+		ret = devm_request_threaded_irq(&client->dev, client->irq,
+						NULL, rfd77402_interrupt_handler,
+						IRQF_ONESHOT,
+						"rfd77402", data);
+		if (ret)
+			return ret;
+
+		data->irq_en = true;
+		dev_dbg(&client->dev, "Using interrupt mode\n");
+	} else {
+		dev_dbg(&client->dev, "Using polling mode\n");
+	}
+
 	indio_dev->info = &rfd77402_info;
 	indio_dev->channels = rfd77402_channels;
 	indio_dev->num_channels = ARRAY_SIZE(rfd77402_channels);
 	indio_dev->name = RFD77402_DRV_NAME;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 
-	ret = rfd77402_init(client);
+	ret = rfd77402_init(data);
 	if (ret < 0)
 		return ret;
 
@@ -316,7 +418,10 @@ static int rfd77402_suspend(struct device *dev)
 
 static int rfd77402_resume(struct device *dev)
 {
-	return rfd77402_init(to_i2c_client(dev));
+	struct iio_dev *indio_dev = dev_get_drvdata(dev);
+	struct rfd77402_data *data = iio_priv(indio_dev);
+
+	return rfd77402_init(data);
 }
 
 static DEFINE_SIMPLE_DEV_PM_OPS(rfd77402_pm_ops, rfd77402_suspend,

-- 
2.43.0

Re: [PATCH v7 2/6] iio: proximity: rfd77402: Align polling timeout with datasheet

[Andy Shevchenko]

On Tue, Jan 27, 2026 at 01:02:16AM +0530, Shrikant Raskar via B4 Relay wrote:

> Update the polling delay to use a 100 ms timeout, as specified
> in the RFD77402 datasheet.

Please, refer at least in the code what is the section and/or table specifies
that...

...

>  		if (ret & RFD77402_ICSR_RESULT)
>  			break;

...here.

Note, it's a requirement to comment all long sleeps (~1ms is considered long),
and some other short sleeps depending on the context.

> -		msleep(20);
> +		msleep(10);
>  	}

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v7 3/6] iio: proximity: rfd77402: Use kernel helper for result polling

[Andy Shevchenko]

On Tue, Jan 27, 2026 at 01:02:17AM +0530, Shrikant Raskar via B4 Relay wrote:

> Replace the manually written polling loop with read_poll_timeout(),
> the kernel's standard helper for waiting on hardware status.This
> makes the code easier to read.
> 
> Move the polling logic into a dedicated helper function, as it will
> be reused by future updates.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v7 6/6] iio: proximity: rfd77402: Add interrupt handling support

[Andy Shevchenko]

On Tue, Jan 27, 2026 at 01:02:20AM +0530, Shrikant Raskar via B4 Relay wrote:

> Add interrupt handling support to enable event-driven data acquisition
> instead of continuous polling. This improves responsiveness, reduces
> CPU overhead, and supports low-power operation by allowing the system
> to remain idle until an interrupt occurs.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
assuming the below is getting be addressed.
...

> +#define RFD77402_ICSR_CLR_CFG   BIT(0)
> +#define RFD77402_ICSR_CLR_TYPE  BIT(1)

You should use tabs for indenting the values. It's inconsistent with the rest.

-- 
With Best Regards,
Andy Shevchenko