1 files changed, 166 insertions, 28 deletions

diff --git a/drivers/iio/adc/ad_sigma_delta.c b/drivers/iio/adc/ad_sigma_delta.c
index 3fd200b34161..d5d81581ab34 100644
--- a/drivers/iio/adc/ad_sigma_delta.c
+++ b/drivers/iio/adc/ad_sigma_delta.c
@@ -29,8 +29,11 @@
 #define AD_SD_COMM_CHAN_MASK	0x3
 
 #define AD_SD_REG_COMM		0x00
+#define AD_SD_REG_STATUS	0x00
 #define AD_SD_REG_DATA		0x03
 
+#define AD_SD_REG_STATUS_RDY	0x80
+
 /**
  * ad_sd_set_comm() - Set communications register
  *
@@ -109,7 +112,7 @@ static int ad_sd_read_reg_raw(struct ad_sigma_delta *sigma_delta,
 		}, {
 			.rx_buf = val,
 			.len = size,
-			.cs_change = sigma_delta->bus_locked,
+			.cs_change = sigma_delta->keep_cs_asserted,
 		},
 	};
 	struct spi_message m;
@@ -178,13 +181,12 @@ EXPORT_SYMBOL_NS_GPL(ad_sd_read_reg, "IIO_AD_SIGMA_DELTA");
  * ad_sd_reset() - Reset the serial interface
  *
  * @sigma_delta: The sigma delta device
- * @reset_length: Number of SCLKs with DIN = 1
  *
  * Returns 0 on success, an error code otherwise.
  **/
-int ad_sd_reset(struct ad_sigma_delta *sigma_delta,
-	unsigned int reset_length)
+int ad_sd_reset(struct ad_sigma_delta *sigma_delta)
 {
+	unsigned int reset_length = sigma_delta->info->num_resetclks;
 	uint8_t *buf;
 	unsigned int size;
 	int ret;
@@ -202,6 +204,107 @@ int ad_sd_reset(struct ad_sigma_delta *sigma_delta,
 }
 EXPORT_SYMBOL_NS_GPL(ad_sd_reset, "IIO_AD_SIGMA_DELTA");
 
+static bool ad_sd_disable_irq(struct ad_sigma_delta *sigma_delta)
+{
+	guard(spinlock_irqsave)(&sigma_delta->irq_lock);
+
+	/* It's already off, return false to indicate nothing was changed */
+	if (sigma_delta->irq_dis)
+		return false;
+
+	sigma_delta->irq_dis = true;
+	disable_irq_nosync(sigma_delta->irq_line);
+	return true;
+}
+
+static void ad_sd_enable_irq(struct ad_sigma_delta *sigma_delta)
+{
+	guard(spinlock_irqsave)(&sigma_delta->irq_lock);
+
+	sigma_delta->irq_dis = false;
+	enable_irq(sigma_delta->irq_line);
+}
+
+#define AD_SD_CLEAR_DATA_BUFLEN 9
+
+/* Called with `sigma_delta->bus_locked == true` only. */
+static int ad_sigma_delta_clear_pending_event(struct ad_sigma_delta *sigma_delta)
+{
+	bool pending_event;
+	unsigned int data_read_len = BITS_TO_BYTES(sigma_delta->info->num_resetclks);
+	u8 *data;
+	struct spi_transfer t[] = {
+		{
+			.len = 1,
+		}, {
+			.len = data_read_len,
+		}
+	};
+	struct spi_message m;
+	int ret;
+
+	/*
+	 * Read R̅D̅Y̅ pin (if possible) or status register to check if there is an
+	 * old event.
+	 */
+	if (sigma_delta->rdy_gpiod) {
+		pending_event = gpiod_get_value(sigma_delta->rdy_gpiod);
+	} else {
+		unsigned int status_reg;
+
+		ret = ad_sd_read_reg(sigma_delta, AD_SD_REG_STATUS, 1, &status_reg);
+		if (ret)
+			return ret;
+
+		pending_event = !(status_reg & AD_SD_REG_STATUS_RDY);
+	}
+
+	if (!pending_event)
+		return 0;
+
+	/*
+	 * In general the size of the data register is unknown. It varies from
+	 * device to device, might be one byte longer if CONTROL.DATA_STATUS is
+	 * set and even varies on some devices depending on which input is
+	 * selected. So send one byte to start reading the data register and
+	 * then just clock for some bytes with DIN (aka MOSI) high to not
+	 * confuse the register access state machine after the data register was
+	 * completely read. Note however that the sequence length must be
+	 * shorter than the reset procedure.
+	 */
+
+	data = kzalloc(data_read_len + 1, GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	spi_message_init(&m);
+	if (sigma_delta->info->has_registers) {
+		unsigned int data_reg = sigma_delta->info->data_reg ?: AD_SD_REG_DATA;
+
+		data[0] = data_reg << sigma_delta->info->addr_shift;
+		data[0] |= sigma_delta->info->read_mask;
+		data[0] |= sigma_delta->comm;
+		t[0].tx_buf = data;
+		spi_message_add_tail(&t[0], &m);
+	}
+
+	/*
+	 * The first transferred byte is part of the real data register,
+	 * so this doesn't need to be 0xff. In the remaining
+	 * `data_read_len - 1` bytes are less than $num_resetclks ones.
+	 */
+	t[1].tx_buf = data + 1;
+	data[1] = 0x00;
+	memset(data + 2, 0xff, data_read_len - 1);
+	spi_message_add_tail(&t[1], &m);
+
+	ret = spi_sync_locked(sigma_delta->spi, &m);
+
+	kfree(data);
+
+	return ret;
+}
+
 int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
 	unsigned int mode, unsigned int channel)
 {
@@ -217,16 +320,18 @@ int ad_sd_calibrate(struct ad_sigma_delta *sigma_delta,
 	sigma_delta->keep_cs_asserted = true;
 	reinit_completion(&sigma_delta->completion);
 
+	ret = ad_sigma_delta_clear_pending_event(sigma_delta);
+	if (ret)
+		goto out;
+
 	ret = ad_sigma_delta_set_mode(sigma_delta, mode);
 	if (ret < 0)
 		goto out;
 
-	sigma_delta->irq_dis = false;
-	enable_irq(sigma_delta->irq_line);
+	ad_sd_enable_irq(sigma_delta);
 	time_left = wait_for_completion_timeout(&sigma_delta->completion, 2 * HZ);
 	if (time_left == 0) {
-		sigma_delta->irq_dis = true;
-		disable_irq_nosync(sigma_delta->irq_line);
+		ad_sd_disable_irq(sigma_delta);
 		ret = -EIO;
 	} else {
 		ret = 0;
@@ -292,10 +397,13 @@ int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
 	sigma_delta->keep_cs_asserted = true;
 	reinit_completion(&sigma_delta->completion);
 
+	ret = ad_sigma_delta_clear_pending_event(sigma_delta);
+	if (ret)
+		goto out_unlock;
+
 	ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_SINGLE);
 
-	sigma_delta->irq_dis = false;
-	enable_irq(sigma_delta->irq_line);
+	ad_sd_enable_irq(sigma_delta);
 	ret = wait_for_completion_interruptible_timeout(
 			&sigma_delta->completion, HZ);
 
@@ -314,14 +422,13 @@ int ad_sigma_delta_single_conversion(struct iio_dev *indio_dev,
 		&raw_sample);
 
 out:
-	if (!sigma_delta->irq_dis) {
-		disable_irq_nosync(sigma_delta->irq_line);
-		sigma_delta->irq_dis = true;
-	}
+	ad_sd_disable_irq(sigma_delta);
 
-	sigma_delta->keep_cs_asserted = false;
 	ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);
 	ad_sigma_delta_disable_one(sigma_delta, chan->address);
+
+out_unlock:
+	sigma_delta->keep_cs_asserted = false;
 	sigma_delta->bus_locked = false;
 	spi_bus_unlock(sigma_delta->spi->controller);
 	iio_device_release_direct_mode(indio_dev);
@@ -392,12 +499,15 @@ static int ad_sd_buffer_postenable(struct iio_dev *indio_dev)
 	sigma_delta->bus_locked = true;
 	sigma_delta->keep_cs_asserted = true;
 
+	ret = ad_sigma_delta_clear_pending_event(sigma_delta);
+	if (ret)
+		goto err_unlock;
+
 	ret = ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_CONTINUOUS);
 	if (ret)
 		goto err_unlock;
 
-	sigma_delta->irq_dis = false;
-	enable_irq(sigma_delta->irq_line);
+	ad_sd_enable_irq(sigma_delta);
 
 	return 0;
 
@@ -414,10 +524,7 @@ static int ad_sd_buffer_postdisable(struct iio_dev *indio_dev)
 	reinit_completion(&sigma_delta->completion);
 	wait_for_completion_timeout(&sigma_delta->completion, HZ);
 
-	if (!sigma_delta->irq_dis) {
-		disable_irq_nosync(sigma_delta->irq_line);
-		sigma_delta->irq_dis = true;
-	}
+	ad_sd_disable_irq(sigma_delta);
 
 	sigma_delta->keep_cs_asserted = false;
 	ad_sigma_delta_set_mode(sigma_delta, AD_SD_MODE_IDLE);
@@ -516,8 +623,7 @@ static irqreturn_t ad_sd_trigger_handler(int irq, void *p)
 
 irq_handled:
 	iio_trigger_notify_done(indio_dev->trig);
-	sigma_delta->irq_dis = false;
-	enable_irq(sigma_delta->irq_line);
+	ad_sd_enable_irq(sigma_delta);
 
 	return IRQ_HANDLED;
 }
@@ -539,12 +645,31 @@ static irqreturn_t ad_sd_data_rdy_trig_poll(int irq, void *private)
 {
 	struct ad_sigma_delta *sigma_delta = private;
 
-	complete(&sigma_delta->completion);
-	disable_irq_nosync(irq);
-	sigma_delta->irq_dis = true;
-	iio_trigger_poll(sigma_delta->trig);
+	/*
+	 * AD7124 and a few others use the same physical line for interrupt
+	 * reporting (R̅D̅Y̅) and MISO.
+	 * As MISO toggles when reading a register, this likely results in a
+	 * pending interrupt. This has two consequences: a) The irq might
+	 * trigger immediately after it's enabled even though the conversion
+	 * isn't done yet; and b) checking the STATUS register's R̅D̅Y̅ flag is
+	 * off-limits as reading that would trigger another irq event.
+	 *
+	 * So read the MOSI line as GPIO (if available) and only trigger the irq
+	 * if the line is active. Without such a GPIO assume this is a valid
+	 * interrupt.
+	 *
+	 * Also as disable_irq_nosync() is used to disable the irq, only act if
+	 * the irq wasn't disabled before.
+	 */
+	if ((!sigma_delta->rdy_gpiod || gpiod_get_value(sigma_delta->rdy_gpiod)) &&
+	    ad_sd_disable_irq(sigma_delta)) {
+		complete(&sigma_delta->completion);
+		iio_trigger_poll(sigma_delta->trig);
 
-	return IRQ_HANDLED;
+		return IRQ_HANDLED;
+	}
+
+	return IRQ_NONE;
 }
 
 /**
@@ -674,11 +799,24 @@ int ad_sd_init(struct ad_sigma_delta *sigma_delta, struct iio_dev *indio_dev,
 		}
 	}
 
+	spin_lock_init(&sigma_delta->irq_lock);
+
 	if (info->irq_line)
 		sigma_delta->irq_line = info->irq_line;
 	else
 		sigma_delta->irq_line = spi->irq;
 
+	sigma_delta->rdy_gpiod = devm_gpiod_get_optional(&spi->dev, "rdy", GPIOD_IN);
+	if (IS_ERR(sigma_delta->rdy_gpiod))
+		return dev_err_probe(&spi->dev, PTR_ERR(sigma_delta->rdy_gpiod),
+				     "Failed to find rdy gpio\n");
+
+	if (sigma_delta->rdy_gpiod && !sigma_delta->irq_line) {
+		sigma_delta->irq_line = gpiod_to_irq(sigma_delta->rdy_gpiod);
+		if (sigma_delta->irq_line < 0)
+			return sigma_delta->irq_line;
+	}
+
 	iio_device_set_drvdata(indio_dev, sigma_delta);
 
 	return 0;