[PATCH v5 7/8] iio: adc: ad7606: Add iio-backend support

From: Guillaume Stols
Date: Tue Oct 15 2024 - 09:58:26 EST

- Basic support for iio backend.
- Supports IIO_CHAN_INFO_SAMP_FREQ R/W.
- Only hardware mode is available, and that IIO_CHAN_INFO_RAW is not
supported if iio-backend mode is selected.

Signed-off-by: Guillaume Stols <gstols@xxxxxxxxxxxx>
---
drivers/iio/adc/Kconfig | 2 +
drivers/iio/adc/ad7606.c | 154 ++++++++++++++++++++++++++++++++++---------
drivers/iio/adc/ad7606.h | 15 +++++
drivers/iio/adc/ad7606_par.c | 92 +++++++++++++++++++++++++-
4 files changed, 231 insertions(+), 32 deletions(-)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 91873f60322d..a57b5f0bc070 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -224,9 +224,11 @@ config AD7606_IFACE_PARALLEL
tristate "Analog Devices AD7606 ADC driver with parallel interface support"
depends on HAS_IOPORT
select AD7606
+ select IIO_BACKEND
help
Say yes here to build parallel interface support for Analog Devices:
ad7605-4, ad7606, ad7606-6, ad7606-4 analog to digital converters (ADC).
+ It also support iio_backended devices for AD7606B.

To compile this driver as a module, choose M here: the
module will be called ad7606_par.
diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c
index 34d377e9ac79..7871552ce5ac 100644
--- a/drivers/iio/adc/ad7606.c
+++ b/drivers/iio/adc/ad7606.c
@@ -21,6 +21,7 @@
#include <linux/units.h>
#include <linux/util_macros.h>

+#include <linux/iio/backend.h>
#include <linux/iio/buffer.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
@@ -191,6 +192,7 @@ EXPORT_SYMBOL_NS_GPL(ad7606_4_info, IIO_AD7606);

const struct ad7606_chip_info ad7606b_info = {
.channels = ad7606_channels_16bit,
+ .max_samplerate = 800 * KILO,
.name = "ad7606b",
.num_adc_channels = 8,
.num_channels = 9,
@@ -490,6 +492,17 @@ static int ad7606_pwm_set_low(struct ad7606_state *st)
return ret;
}

+static int ad7606_pwm_set_swing(struct ad7606_state *st)
+{
+ struct pwm_state cnvst_pwm_state;
+
+ pwm_get_state(st->cnvst_pwm, &cnvst_pwm_state);
+ cnvst_pwm_state.enabled = true;
+ cnvst_pwm_state.duty_cycle = cnvst_pwm_state.period / 2;
+
+ return pwm_apply_might_sleep(st->cnvst_pwm, &cnvst_pwm_state);
+}
+
static bool ad7606_pwm_is_swinging(struct ad7606_state *st)
{
struct pwm_state cnvst_pwm_state;
@@ -576,11 +589,22 @@ static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch,
if (ret < 0)
return ret;
}
- ret = wait_for_completion_timeout(&st->completion,
- msecs_to_jiffies(1000));
- if (!ret) {
- ret = -ETIMEDOUT;
- goto error_ret;
+
+ /*
+ * If no backend, wait for the interruption on busy pin, otherwise just add
+ * a delay to leave time for the data to be available. For now, the latter
+ * will not happen because IIO_CHAN_INFO_RAW is not supported for the backend.
+ * TODO: Add support for reading a single value when the backend is used.
+ */
+ if (!st->back) {
+ ret = wait_for_completion_timeout(&st->completion,
+ msecs_to_jiffies(1000));
+ if (!ret) {
+ ret = -ETIMEDOUT;
+ goto error_ret;
+ }
+ } else {
+ fsleep(1);
}

ret = ad7606_read_samples(st);
@@ -620,6 +644,7 @@ static int ad7606_read_raw(struct iio_dev *indio_dev,
int ret, ch = 0;
struct ad7606_state *st = iio_priv(indio_dev);
struct ad7606_chan_scale *cs;
+ struct pwm_state cnvst_pwm_state;

switch (m) {
case IIO_CHAN_INFO_RAW:
@@ -640,6 +665,14 @@ static int ad7606_read_raw(struct iio_dev *indio_dev,
case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
*val = st->oversampling;
return IIO_VAL_INT;
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ /*
+ * TODO: return the real frequency intead of the requested one once
+ * pwm_get_state_hw comes upstream.
+ */
+ pwm_get_state(st->cnvst_pwm, &cnvst_pwm_state);
+ *val = DIV_ROUND_CLOSEST_ULL(NSEC_PER_SEC, cnvst_pwm_state.period);
+ return IIO_VAL_INT;
}
return -EINVAL;
}
@@ -732,6 +765,10 @@ static int ad7606_write_raw(struct iio_dev *indio_dev,
return ret;

return 0;
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ if (val < 0 && val2 != 0)
+ return -EINVAL;
+ return ad7606_set_sampling_freq(st, val);
default:
return -EINVAL;
}
@@ -914,14 +951,50 @@ static int ad7606_read_avail(struct iio_dev *indio_dev,
return -EINVAL;
}

+static int ad7606_backend_buffer_postenable(struct iio_dev *indio_dev)
+{
+ struct ad7606_state *st = iio_priv(indio_dev);
+
+ return ad7606_pwm_set_swing(st);
+}
+
+static int ad7606_backend_buffer_predisable(struct iio_dev *indio_dev)
+{
+ struct ad7606_state *st = iio_priv(indio_dev);
+
+ return ad7606_pwm_set_low(st);
+}
+
+static int ad7606_update_scan_mode(struct iio_dev *indio_dev,
+ const unsigned long *scan_mask)
+{
+ struct ad7606_state *st = iio_priv(indio_dev);
+
+ /*
+ * The update scan mode is only for iio backend compatible drivers.
+ * If the specific update_scan_mode is not defined in the bus ops,
+ * just do nothing and return 0.
+ */
+ if (!st->bops->update_scan_mode)
+ return 0;
+
+ return st->bops->update_scan_mode(indio_dev, scan_mask);
+}
+
static const struct iio_buffer_setup_ops ad7606_buffer_ops = {
.postenable = &ad7606_buffer_postenable,
.predisable = &ad7606_buffer_predisable,
};

+static const struct iio_buffer_setup_ops ad7606_backend_buffer_ops = {
+ .postenable = &ad7606_backend_buffer_postenable,
+ .predisable = &ad7606_backend_buffer_predisable,
+};
+
static const struct iio_info ad7606_info_no_os_or_range = {
.read_raw = &ad7606_read_raw,
.validate_trigger = &ad7606_validate_trigger,
+ .update_scan_mode = &ad7606_update_scan_mode,
};

static const struct iio_info ad7606_info_os_and_range = {
@@ -929,6 +1002,7 @@ static const struct iio_info ad7606_info_os_and_range = {
.write_raw = &ad7606_write_raw,
.attrs = &ad7606_attribute_group_os_and_range,
.validate_trigger = &ad7606_validate_trigger,
+ .update_scan_mode = &ad7606_update_scan_mode,
};

static const struct iio_info ad7606_info_sw_mode = {
@@ -937,6 +1011,7 @@ static const struct iio_info ad7606_info_sw_mode = {
.read_avail = &ad7606_read_avail,
.debugfs_reg_access = &ad7606_reg_access,
.validate_trigger = &ad7606_validate_trigger,
+ .update_scan_mode = &ad7606_update_scan_mode,
};

static const struct iio_info ad7606_info_os = {
@@ -944,6 +1019,7 @@ static const struct iio_info ad7606_info_os = {
.write_raw = &ad7606_write_raw,
.attrs = &ad7606_attribute_group_os,
.validate_trigger = &ad7606_validate_trigger,
+ .update_scan_mode = &ad7606_update_scan_mode,
};

static const struct iio_info ad7606_info_range = {
@@ -951,6 +1027,7 @@ static const struct iio_info ad7606_info_range = {
.write_raw = &ad7606_write_raw,
.attrs = &ad7606_attribute_group_range,
.validate_trigger = &ad7606_validate_trigger,
+ .update_scan_mode = &ad7606_update_scan_mode,
};

static const struct iio_trigger_ops ad7606_trigger_ops = {
@@ -1070,8 +1147,6 @@ int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
indio_dev->channels = st->chip_info->channels;
indio_dev->num_channels = st->chip_info->num_channels;

- init_completion(&st->completion);
-
ret = ad7606_reset(st);
if (ret)
dev_warn(st->dev, "failed to RESET: no RESET GPIO specified\n");
@@ -1118,34 +1193,51 @@ int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
if (ret)
return ret;
}
- st->trig = devm_iio_trigger_alloc(dev, "%s-dev%d",
- indio_dev->name,
- iio_device_id(indio_dev));
- if (!st->trig)
- return -ENOMEM;

- st->trig->ops = &ad7606_trigger_ops;
- iio_trigger_set_drvdata(st->trig, indio_dev);
- ret = devm_iio_trigger_register(dev, st->trig);
- if (ret)
- return ret;
+ if (st->bops->iio_backend_config) {
+ /*
+ * If there is a backend, the PWM should not overpass the maximum sampling
+ * frequency the chip supports.
+ */
+ ret = ad7606_set_sampling_freq(st,
+ chip_info->max_samplerate ? : 2 * KILO);
+ if (ret)
+ return ret;
+
+ ret = st->bops->iio_backend_config(dev, indio_dev);
+ if (ret)
+ return ret;

- indio_dev->trig = iio_trigger_get(st->trig);
+ indio_dev->setup_ops = &ad7606_backend_buffer_ops;
+ } else {
+ init_completion(&st->completion);
+ st->trig = devm_iio_trigger_alloc(dev, "%s-dev%d",
+ indio_dev->name,
+ iio_device_id(indio_dev));
+ if (!st->trig)
+ return -ENOMEM;
+
+ st->trig->ops = &ad7606_trigger_ops;
+ iio_trigger_set_drvdata(st->trig, indio_dev);
+ ret = devm_iio_trigger_register(dev, st->trig);
+ if (ret)
+ return ret;

- ret = devm_request_threaded_irq(dev, irq,
- NULL,
- &ad7606_interrupt,
- IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
- chip_info->name, indio_dev);
- if (ret)
- return ret;
+ indio_dev->trig = iio_trigger_get(st->trig);

- ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
- &iio_pollfunc_store_time,
- &ad7606_trigger_handler,
- &ad7606_buffer_ops);
- if (ret)
- return ret;
+ ret = devm_request_threaded_irq(dev, irq, NULL, &ad7606_interrupt,
+ IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+ chip_info->name, indio_dev);
+ if (ret)
+ return ret;
+
+ ret = devm_iio_triggered_buffer_setup(dev, indio_dev,
+ &iio_pollfunc_store_time,
+ &ad7606_trigger_handler,
+ &ad7606_buffer_ops);
+ if (ret)
+ return ret;
+ }

return devm_iio_device_register(dev, indio_dev);
}
diff --git a/drivers/iio/adc/ad7606.h b/drivers/iio/adc/ad7606.h
index b26a11b2eba1..2c629a15cc33 100644
--- a/drivers/iio/adc/ad7606.h
+++ b/drivers/iio/adc/ad7606.h
@@ -61,6 +61,12 @@

#define AD7616_CHANNEL(num) AD7606_SW_CHANNEL(num, 16)

+#define AD7606_BI_CHANNEL(num) \
+ AD760X_CHANNEL(num, 0, \
+ BIT(IIO_CHAN_INFO_SCALE), \
+ BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
+ BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), 16)
+
struct ad7606_state;

typedef int (*ad7606_scale_setup_cb_t)(struct ad7606_state *st,
@@ -69,6 +75,7 @@ typedef int (*ad7606_scale_setup_cb_t)(struct ad7606_state *st,
/**
* struct ad7606_chip_info - chip specific information
* @channels: channel specification
+ * @max_samplerate: maximum supported samplerate
* @name device name
* @num_channels: number of channels
* @num_adc_channels the number of channels the ADC actually inputs.
@@ -82,6 +89,7 @@ typedef int (*ad7606_scale_setup_cb_t)(struct ad7606_state *st,
*/
struct ad7606_chip_info {
const struct iio_chan_spec *channels;
+ unsigned int max_samplerate;
const char *name;
unsigned int num_adc_channels;
unsigned int num_channels;
@@ -152,6 +160,7 @@ struct ad7606_state {
bool sw_mode_en;
const unsigned int *oversampling_avail;
unsigned int num_os_ratios;
+ struct iio_backend *back;
int (*write_scale)(struct iio_dev *indio_dev, int ch, int val);
int (*write_os)(struct iio_dev *indio_dev, int val);

@@ -180,16 +189,21 @@ struct ad7606_state {

/**
* struct ad7606_bus_ops - driver bus operations
+ * @iio_backend_config function pointer for configuring the iio_backend for
+ * the compatibles that use it
* @read_block function pointer for reading blocks of data
* @sw_mode_config: pointer to a function which configured the device
* for software mode
* @reg_read function pointer for reading spi register
* @reg_write function pointer for writing spi register
* @write_mask function pointer for write spi register with mask
+ * @update_scan_mode function pointer for handling the calls to iio_info's update_scan
+ * mode when enabling/disabling channels.
* @rd_wr_cmd pointer to the function which calculates the spi address
*/
struct ad7606_bus_ops {
/* more methods added in future? */
+ int (*iio_backend_config)(struct device *dev, struct iio_dev *indio_dev);
int (*read_block)(struct device *dev, int num, void *data);
int (*sw_mode_config)(struct iio_dev *indio_dev);
int (*reg_read)(struct ad7606_state *st, unsigned int addr);
@@ -200,6 +214,7 @@ struct ad7606_bus_ops {
unsigned int addr,
unsigned long mask,
unsigned int val);
+ int (*update_scan_mode)(struct iio_dev *indio_dev, const unsigned long *scan_mask);
u16 (*rd_wr_cmd)(int addr, char isWriteOp);
};

diff --git a/drivers/iio/adc/ad7606_par.c b/drivers/iio/adc/ad7606_par.c
index b87be2f1ca04..6946ff00e4cb 100644
--- a/drivers/iio/adc/ad7606_par.c
+++ b/drivers/iio/adc/ad7606_par.c
@@ -2,7 +2,8 @@
/*
* AD7606 Parallel Interface ADC driver
*
- * Copyright 2011 Analog Devices Inc.
+ * Copyright 2011 - 2024 Analog Devices Inc.
+ * Copyright 2024 BayLibre SAS.
*/

#include <linux/err.h>
@@ -14,9 +15,82 @@
#include <linux/property.h>
#include <linux/types.h>

+#include <linux/iio/backend.h>
#include <linux/iio/iio.h>
+
#include "ad7606.h"

+static const struct iio_chan_spec ad7606b_bi_channels[] = {
+ AD7606_BI_CHANNEL(0),
+ AD7606_BI_CHANNEL(1),
+ AD7606_BI_CHANNEL(2),
+ AD7606_BI_CHANNEL(3),
+ AD7606_BI_CHANNEL(4),
+ AD7606_BI_CHANNEL(5),
+ AD7606_BI_CHANNEL(6),
+ AD7606_BI_CHANNEL(7),
+};
+
+static int ad7606_bi_update_scan_mode(struct iio_dev *indio_dev, const unsigned long *scan_mask)
+{
+ struct ad7606_state *st = iio_priv(indio_dev);
+ unsigned int c, ret;
+
+ for (c = 0; c < indio_dev->num_channels; c++) {
+ if (test_bit(c, scan_mask))
+ ret = iio_backend_chan_enable(st->back, c);
+ else
+ ret = iio_backend_chan_disable(st->back, c);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int ad7606_bi_setup_iio_backend(struct device *dev, struct iio_dev *indio_dev)
+{
+ struct ad7606_state *st = iio_priv(indio_dev);
+ unsigned int ret, c;
+ struct iio_backend_data_fmt data = {
+ .sign_extend = true,
+ .enable = true,
+ };
+
+ st->back = devm_iio_backend_get(dev, NULL);
+ if (IS_ERR(st->back))
+ return PTR_ERR(st->back);
+
+ /* If the device is iio_backend powered the PWM is mandatory */
+ if (!st->cnvst_pwm)
+ return dev_err_probe(st->dev, -EINVAL,
+ "A PWM is mandatory when using backend.\n");
+
+ ret = devm_iio_backend_request_buffer(dev, st->back, indio_dev);
+ if (ret)
+ return ret;
+
+ ret = devm_iio_backend_enable(dev, st->back);
+ if (ret)
+ return ret;
+
+ for (c = 0; c < indio_dev->num_channels; c++) {
+ ret = iio_backend_data_format_set(st->back, c, &data);
+ if (ret)
+ return ret;
+ }
+
+ indio_dev->channels = ad7606b_bi_channels;
+ indio_dev->num_channels = 8;
+
+ return 0;
+}
+
+static const struct ad7606_bus_ops ad7606_bi_bops = {
+ .iio_backend_config = ad7606_bi_setup_iio_backend,
+ .update_scan_mode = ad7606_bi_update_scan_mode,
+};
+
static int ad7606_par16_read_block(struct device *dev,
int count, void *buf)
{
@@ -96,9 +170,22 @@ static int ad7606_par_probe(struct platform_device *pdev)
void __iomem *addr;
resource_size_t remap_size;
int irq;
+ struct iio_backend *back;

+ /*
+ * If a firmware node is available (ACPI or DT), platform_device_id is null
+ * and we must use get_match_data.
+ */
if (dev_fwnode(&pdev->dev)) {
chip_info = device_get_match_data(&pdev->dev);
+ if (device_property_present(&pdev->dev, "io-backends"))
+ /*
+ * If a backend is available ,call the core probe with backend
+ * bops, otherwise use the former bops.
+ */
+ return ad7606_probe(&pdev->dev, 0, NULL,
+ chip_info,
+ &ad7606_bi_bops);
} else {
id = platform_get_device_id(pdev);
chip_info = (const struct ad7606_chip_info *)id->driver_data;
@@ -124,6 +211,7 @@ static const struct platform_device_id ad7606_driver_ids[] = {
{ .name = "ad7606-4", .driver_data = (kernel_ulong_t)&ad7606_4_info, },
{ .name = "ad7606-6", .driver_data = (kernel_ulong_t)&ad7606_6_info, },
{ .name = "ad7606-8", .driver_data = (kernel_ulong_t)&ad7606_8_info, },
+ { .name = "ad7606b", .driver_data = (kernel_ulong_t)&ad7606b_info, },
{ }
};
MODULE_DEVICE_TABLE(platform, ad7606_driver_ids);
@@ -133,6 +221,7 @@ static const struct of_device_id ad7606_of_match[] = {
{ .compatible = "adi,ad7606-4", .data = &ad7606_4_info },
{ .compatible = "adi,ad7606-6", .data = &ad7606_6_info },
{ .compatible = "adi,ad7606-8", .data = &ad7606_8_info },
+ { .compatible = "adi,ad7606b", .data = &ad7606b_info },
{ }
};
MODULE_DEVICE_TABLE(of, ad7606_of_match);
@@ -152,3 +241,4 @@ MODULE_AUTHOR("Michael Hennerich <michael.hennerich@xxxxxxxxxx>");
MODULE_DESCRIPTION("Analog Devices AD7606 ADC");
MODULE_LICENSE("GPL v2");
MODULE_IMPORT_NS(IIO_AD7606);
+MODULE_IMPORT_NS(IIO_BACKEND);

--
2.34.1