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

Guillaume Stols
2024-08-15T12:12:12Z

- 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.

A small correction was added to the driver's file name in the Kconfig
file's description.

Signed-off-by: Guillaume Stols <gstols@baylibre.com>
---
drivers/iio/adc/Kconfig | 3 +-
drivers/iio/adc/ad7606.c | 103 +++++++++++++++++++++++++++++++++++--------
drivers/iio/adc/ad7606.h | 16 +++++++
drivers/iio/adc/ad7606_par.c | 98 +++++++++++++++++++++++++++++++++++++++-
4 files changed, 200 insertions(+), 20 deletions(-)

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 88e8ce2e78b3..01248b6df868 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -227,9 +227,10 @@ config AD7606_IFACE_PARALLEL
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_parallel.
+ module will be called ad7606_par.

config AD7606_IFACE_SPI
tristate "Analog Devices AD7606 ADC driver with spi interface support"
diff --git a/drivers/iio/adc/ad7606.c b/drivers/iio/adc/ad7606.c
index 99d5ca5c2348..a753d5caa9f8 100644
--- a/drivers/iio/adc/ad7606.c
+++ b/drivers/iio/adc/ad7606.c
@@ -21,6 +21,7 @@
#include <linux/util_macros.h>
#include <linux/units.h>

+#include <linux/iio/backend.h>
#include <linux/iio/iio.h>
#include <linux/iio/buffer.h>
#include <linux/iio/sysfs.h>
@@ -148,7 +149,15 @@ static int ad7606_set_sampling_freq(struct ad7606_state *st, unsigned long freq)

static int ad7606_read_samples(struct ad7606_state *st)
{
- unsigned int num = st->chip_info->num_channels - 1;
+ unsigned int num = st->chip_info->num_channels;
+
+ /*
+ * Timestamp channel does not contain sample, and no timestamp channel if
+ * backend is used.
+ */
+ if (!st->back)
+ num--;
+
u16 *data = st->data;
int ret;

@@ -220,11 +229,15 @@ static int ad7606_scan_direct(struct iio_dev *indio_dev, unsigned int ch)
if (!ret)
return ret;
}
- ret = wait_for_completion_timeout(&st->completion,
- msecs_to_jiffies(1000));
- if (!ret) {
- ret = -ETIMEDOUT;
- goto error_ret;
+
+ /* backend manages interruptions by itself.*/
+ if (!st->back) {
+ ret = wait_for_completion_timeout(&st->completion,
+ msecs_to_jiffies(1000));
+ if (!ret) {
+ ret = -ETIMEDOUT;
+ goto error_ret;
+ }
}

ret = ad7606_read_samples(st);
@@ -271,6 +284,12 @@ 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:
+ pwm_get_state_hw(st->cnvst_pwm, &cnvst_pwm_state);
+ /* If the PWM is swinging, return the real frequency, otherwise 0 */
+ *val = ad7606_pwm_is_swinging(st) ?
+ DIV_ROUND_CLOSEST_ULL(NSEC_PER_SEC, cnvst_pwm_state.period) : 0;
+ return IIO_VAL_INT;
}
return -EINVAL;
}
@@ -360,6 +379,8 @@ static int ad7606_write_raw(struct iio_dev *indio_dev,
return ret;

return 0;
+ case IIO_CHAN_INFO_SAMP_FREQ:
+ return ad7606_set_sampling_freq(st, val);
default:
return -EINVAL;
}
@@ -482,7 +503,6 @@ static int ad7606_buffer_postenable(struct iio_dev *indio_dev)
struct ad7606_state *st = iio_priv(indio_dev);

gpiod_set_value(st->gpio_convst, 1);
- ad7606_pwm_set_swing(st);

return 0;
}
@@ -492,19 +512,53 @@ static int ad7606_buffer_predisable(struct iio_dev *indio_dev)
struct ad7606_state *st = iio_priv(indio_dev);

gpiod_set_value(st->gpio_convst, 0);
- ad7606_pwm_set_low(st);

return 0;
}

+static int ad7606_pwm_buffer_postenable(struct iio_dev *indio_dev)
+{
+ struct ad7606_state *st = iio_priv(indio_dev);
+
+ return ad7606_pwm_set_swing(st);
+}
+
+static int ad7606_pwm_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 st->bops->update_scan_mode(indio_dev, scan_mask);
+ else
+ return 0;
+}
+
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_pwm_buffer_ops = {
+ .postenable = &ad7606_pwm_buffer_postenable,
+ .predisable = &ad7606_pwm_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 = {
@@ -512,6 +566,7 @@ 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_os_range_and_debug = {
@@ -520,6 +575,7 @@ static const struct iio_info ad7606_info_os_range_and_debug = {
.debugfs_reg_access = &ad7606_reg_access,
.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_os = {
@@ -527,6 +583,7 @@ 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 = {
@@ -534,6 +591,7 @@ 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 = {
@@ -602,8 +660,6 @@ 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");
@@ -635,7 +691,7 @@ int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
return ret;
}

- /* If convst pin is not defined, setup PWM*/
+ /* If convst pin is not defined, setup PWM */
if (!st->gpio_convst) {
st->cnvst_pwm = devm_pwm_get(dev, NULL);
if (IS_ERR(st->cnvst_pwm))
@@ -671,14 +727,25 @@ int ad7606_probe(struct device *dev, int irq, void __iomem *base_address,
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;

+ if (st->bops->iio_backend_config) {
+ st->bops->iio_backend_config(dev, indio_dev);
+ indio_dev->setup_ops = &ad7606_pwm_buffer_ops;
+ } else {
+ /* Reserve the PWM use only for backend (force gpio_convst definition)*/
+ if (!st->gpio_convst)
+ return dev_err_probe(dev, -EINVAL,
+ "Convst pin must be defined when not in backend mode");
+
+ init_completion(&st->completion);
+ ret = devm_request_threaded_irq(dev, irq,
+ NULL,
+ &ad7606_interrupt,
+ IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+ chip_info->name, indio_dev);
+ if (ret)
+ return ret;
+ }
return devm_iio_device_register(dev, indio_dev);
}
EXPORT_SYMBOL_NS_GPL(ad7606_probe, IIO_AD7606);
diff --git a/drivers/iio/adc/ad7606.h b/drivers/iio/adc/ad7606.h
index aab8fefb84be..9a098cd77812 100644
--- a/drivers/iio/adc/ad7606.h
+++ b/drivers/iio/adc/ad7606.h
@@ -34,6 +34,12 @@
BIT(IIO_CHAN_INFO_SCALE), \
BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO))

+#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))
+
#define AD7616_CHANNEL(num) \
AD760X_CHANNEL(num, BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),\
0, BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO))
@@ -61,6 +67,7 @@ enum ad7606_supported_device_ids {
* @os_req_reset some devices require a reset to update oversampling
* @init_delay_ms required delay in miliseconds for initialization
* after a restart
+ * @has_backend defines if a backend is available for the given chip
*/
struct ad7606_chip_info {
enum ad7606_supported_device_ids id;
@@ -71,6 +78,7 @@ struct ad7606_chip_info {
unsigned int oversampling_num;
bool os_req_reset;
unsigned long init_delay_ms;
+ bool has_backend;
};

/**
@@ -116,6 +124,7 @@ struct ad7606_state {
unsigned int num_scales;
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);

@@ -140,16 +149,21 @@ 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);
@@ -160,6 +174,7 @@ 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);
};

@@ -264,6 +279,7 @@ static const struct ad7606_chip_info ad7606b_info = {
.num_channels = 9,
.oversampling_avail = ad7606_oversampling_avail,
.oversampling_num = ARRAY_SIZE(ad7606_oversampling_avail),
+ .has_backend = true,
.name = "ad7606B",
.id = ID_AD7606B,
};
diff --git a/drivers/iio/adc/ad7606_par.c b/drivers/iio/adc/ad7606_par.c
index d83c0edc1e31..5c8a04556e25 100644
--- a/drivers/iio/adc/ad7606_par.c
+++ b/drivers/iio/adc/ad7606_par.c
@@ -3,6 +3,8 @@
* AD7606 Parallel Interface ADC driver
*
* Copyright 2011 Analog Devices Inc.
+ * Copyright 2024 Analog Devices Inc.
+ * Copyright 2024 BayLibre SAS.
*/

#include <linux/mod_devicetable.h>
@@ -11,10 +13,86 @@
#include <linux/types.h>
#include <linux/err.h>
#include <linux/io.h>
+#include <linux/pwm.h>
+#include <linux/gpio.h>
+#include <linux/delay.h>

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

+#ifdef CONFIG_IIO_BACKEND
+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;
+
+ 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 -EINVAL;
+
+ 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;
+
+ struct iio_backend_data_fmt data = {
+ .sign_extend = true,
+ .enable = true,
+ };
+ 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,
+};
+#endif
+
static int ad7606_par16_read_block(struct device *dev,
int count, void *buf)
{
@@ -52,7 +130,20 @@ static int ad7606_par_probe(struct platform_device *pdev)
void __iomem *addr;
resource_size_t remap_size;
int irq;
-
+#ifdef CONFIG_IIO_BACKEND
+ struct iio_backend *back;
+
+ /*For now, only the AD7606B is backend compatible.*/
+ if (chip_info->has_backend) {
+ back = devm_iio_backend_get(&pdev->dev, NULL);
+ if (IS_ERR(back))
+ return PTR_ERR(back);
+
+ return ad7606_probe(&pdev->dev, 0, NULL,
+ chip_info,
+ &ad7606_bi_bops);
+ }
+#endif
irq = platform_get_irq(pdev, 0);
if (irq < 0)
return irq;
@@ -74,6 +165,7 @@ 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);
@@ -83,6 +175,7 @@ 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);
@@ -102,3 +195,6 @@ MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
MODULE_DESCRIPTION("Analog Devices AD7606 ADC");
MODULE_LICENSE("GPL v2");
MODULE_IMPORT_NS(IIO_AD7606);
+#ifdef CONFIG_IIO_BACKEND
+MODULE_IMPORT_NS(IIO_BACKEND);
+#endif

--
2.34.1