[PATCH v5 5/9] iio: adc: mcp3911: add support for buffers

From: Marcus Folkesson
Date: Tue Aug 09 2022 - 03:32:58 EST

Add support for buffers to make the driver fit for more usecases.

Signed-off-by: Marcus Folkesson <marcus.folkesson@xxxxxxxxx>
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
---
drivers/iio/adc/Kconfig | 2 +
drivers/iio/adc/mcp3911.c | 102 +++++++++++++++++++++++++++++++++++---
2 files changed, 97 insertions(+), 7 deletions(-)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 7fe5930891e0..3b5db59f3931 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -718,6 +718,8 @@ config MCP3422
config MCP3911
tristate "Microchip Technology MCP3911 driver"
depends on SPI
+ select IIO_BUFFER
+ select IIO_TRIGGERED_BUFFER
help
Say yes here to build support for Microchip Technology's MCP3911
analog to digital converter.
diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c
index 29d73b847f5f..87ab7e24ab08 100644
--- a/drivers/iio/adc/mcp3911.c
+++ b/drivers/iio/adc/mcp3911.c
@@ -5,16 +5,24 @@
* Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@xxxxxxxxx>
* Copyright (C) 2018 Kent Gustavsson <kent@xxxxxxxxxx>
*/
+#include <linux/bitfield.h>
+#include <linux/bits.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/trigger.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>

+#include <asm/unaligned.h>
+
#define MCP3911_REG_CHANNEL0 0x00
#define MCP3911_REG_CHANNEL1 0x03
#define MCP3911_REG_MOD 0x06
@@ -22,6 +30,7 @@
#define MCP3911_REG_GAIN 0x09

#define MCP3911_REG_STATUSCOM 0x0a
+#define MCP3911_STATUSCOM_READ GENMASK(7, 6)
#define MCP3911_STATUSCOM_CH1_24WIDTH BIT(4)
#define MCP3911_STATUSCOM_CH0_24WIDTH BIT(3)
#define MCP3911_STATUSCOM_EN_OFFCAL BIT(2)
@@ -54,6 +63,13 @@ struct mcp3911 {
struct regulator *vref;
struct clk *clki;
u32 dev_addr;
+ struct {
+ u32 channels[MCP3911_NUM_CHANNELS];
+ s64 ts __aligned(8);
+ } scan;
+
+ u8 tx_buf __aligned(IIO_DMA_MINALIGN);
+ u8 rx_buf[MCP3911_NUM_CHANNELS * 3];
};

static int mcp3911_read(struct mcp3911 *adc, u8 reg, u32 *val, u8 len)
@@ -196,16 +212,68 @@ static int mcp3911_write_raw(struct iio_dev *indio_dev,
.type = IIO_VOLTAGE, \
.indexed = 1, \
.channel = idx, \
+ .scan_index = idx, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
BIT(IIO_CHAN_INFO_OFFSET) | \
BIT(IIO_CHAN_INFO_SCALE), \
+ .scan_type = { \
+ .sign = 's', \
+ .realbits = 24, \
+ .storagebits = 32, \
+ .endianness = IIO_BE, \
+ }, \
}

static const struct iio_chan_spec mcp3911_channels[] = {
MCP3911_CHAN(0),
MCP3911_CHAN(1),
+ IIO_CHAN_SOFT_TIMESTAMP(2),
};

+static irqreturn_t mcp3911_trigger_handler(int irq, void *p)
+{
+ struct iio_poll_func *pf = p;
+ struct iio_dev *indio_dev = pf->indio_dev;
+ struct mcp3911 *adc = iio_priv(indio_dev);
+ struct spi_transfer xfer[] = {
+ {
+ .tx_buf = &adc->tx_buf,
+ .len = 1,
+ }, {
+ .rx_buf = adc->rx_buf,
+ .len = sizeof(adc->rx_buf),
+ },
+ };
+
+ int scan_index;
+ int i = 0;
+ int ret;
+
+ mutex_lock(&adc->lock);
+ adc->tx_buf = MCP3911_REG_READ(MCP3911_CHANNEL(0), adc->dev_addr);
+ ret = spi_sync_transfer(adc->spi, xfer, ARRAY_SIZE(xfer));
+ if (ret < 0) {
+ dev_warn(&adc->spi->dev,
+ "failed to get conversion data\n");
+ goto out;
+ }
+
+ for_each_set_bit(scan_index, indio_dev->active_scan_mask,
+ indio_dev->masklength) {
+ const struct iio_chan_spec *scan_chan = &indio_dev->channels[scan_index];
+
+ adc->scan.channels[i] = get_unaligned_be24(&adc->rx_buf[scan_chan->channel * 3]);
+ i++;
+ }
+ iio_push_to_buffers_with_timestamp(indio_dev, &adc->scan,
+ iio_get_time_ns(indio_dev));
+out:
+ mutex_unlock(&adc->lock);
+ iio_trigger_notify_done(indio_dev->trig);
+
+ return IRQ_HANDLED;
+}
+
static const struct iio_info mcp3911_info = {
.read_raw = mcp3911_read_raw,
.write_raw = mcp3911_write_raw,
@@ -214,7 +282,7 @@ static const struct iio_info mcp3911_info = {
static int mcp3911_config(struct mcp3911 *adc)
{
struct device *dev = &adc->spi->dev;
- u32 configreg;
+ u32 regval;
int ret;

ret = device_property_read_u32(dev, "microchip,device-addr", &adc->dev_addr);
@@ -233,29 +301,43 @@ static int mcp3911_config(struct mcp3911 *adc)
}
dev_dbg(&adc->spi->dev, "use device address %i\n", adc->dev_addr);

- ret = mcp3911_read(adc, MCP3911_REG_CONFIG, &configreg, 2);
+ ret = mcp3911_read(adc, MCP3911_REG_CONFIG, &regval, 2);
if (ret)
return ret;

+ regval &= ~MCP3911_CONFIG_VREFEXT;
if (adc->vref) {
dev_dbg(&adc->spi->dev, "use external voltage reference\n");
- configreg |= MCP3911_CONFIG_VREFEXT;
+ regval |= FIELD_PREP(MCP3911_CONFIG_VREFEXT, 1);
} else {
dev_dbg(&adc->spi->dev,
"use internal voltage reference (1.2V)\n");
- configreg &= ~MCP3911_CONFIG_VREFEXT;
+ regval |= FIELD_PREP(MCP3911_CONFIG_VREFEXT, 0);
}

+ regval &= ~MCP3911_CONFIG_CLKEXT;
if (adc->clki) {
dev_dbg(&adc->spi->dev, "use external clock as clocksource\n");
- configreg |= MCP3911_CONFIG_CLKEXT;
+ regval |= FIELD_PREP(MCP3911_CONFIG_CLKEXT, 1);
} else {
dev_dbg(&adc->spi->dev,
"use crystal oscillator as clocksource\n");
- configreg &= ~MCP3911_CONFIG_CLKEXT;
+ regval |= FIELD_PREP(MCP3911_CONFIG_CLKEXT, 0);
}

- return mcp3911_write(adc, MCP3911_REG_CONFIG, configreg, 2);
+ ret = mcp3911_write(adc, MCP3911_REG_CONFIG, regval, 2);
+ if (ret)
+ return ret;
+
+ ret = mcp3911_read(adc, MCP3911_REG_STATUSCOM, &regval, 2);
+ if (ret)
+ return ret;
+
+ /* Address counter incremented, cycle through register types */
+ regval &= ~MCP3911_STATUSCOM_READ;
+ regval |= FIELD_PREP(MCP3911_STATUSCOM_READ, 0x02);
+
+ return mcp3911_write(adc, MCP3911_REG_STATUSCOM, regval, 2);
}

static void mcp3911_cleanup_clock(void *_adc)
@@ -343,6 +425,12 @@ static int mcp3911_probe(struct spi_device *spi)

mutex_init(&adc->lock);

+ ret = devm_iio_triggered_buffer_setup(&spi->dev, indio_dev,
+ NULL,
+ mcp3911_trigger_handler, NULL);
+ if (ret)
+ return ret;
+
return devm_iio_device_register(&adc->spi->dev, indio_dev);
}

--
2.37.1