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Message-Id: <20260121-b4-rfd77402_v5-v6-5-5b944d0605dd@gmail.com>
Date: Wed, 21 Jan 2026 02:05:45 +0530
From: Shrikant Raskar via B4 Relay <devnull+raskar.shree97.gmail.com@...nel.org>
To: Jonathan Cameron <jic23@...nel.org>,
David Lechner <dlechner@...libre.com>,
Nuno Sá <nuno.sa@...log.com>,
Andy Shevchenko <andy@...nel.org>
Cc: skhan@...uxfoundation.org, david.hunter.linux@...il.com,
raskar.shree97@...il.com, linux-iio@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v6 5/5] iio: proximity: rfd77402: Add interrupt handling
support
From: Shrikant Raskar <raskar.shree97@...il.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@...il.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 dd57156a7859..7de6faad2b22 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 ret;
+ if (data->irq_en) {
+ reinit_completion(&data->completion);
+ return rfd77402_wait_for_irq(data);
+ }
+
return read_poll_timeout(i2c_smbus_read_byte_data, ret,
ret & RFD77402_ICSR_RESULT,
10 * USEC_PER_MSEC,
@@ -196,8 +254,20 @@ 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,
@@ -205,10 +275,26 @@ 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 */
@@ -288,13 +374,29 @@ 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;
@@ -312,7 +414,10 @@ 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
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