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Date: Tue, 08 Jan 2013 11:27:26 +0100
From: Lars-Peter Clausen <lars@...afoo.de>
To: Christophe Leroy <christophe.leroy@....fr>
CC: Jonathan Cameron <jic23@....ac.uk>, linux-kernel@...r.kernel.org,
linux-iio@...r.kernel.org, patrick.vasseur@....fr
Subject: Re: [PATCH] IIO ADC support for AD7923
On 01/08/2013 09:42 AM, Christophe Leroy wrote:
> This patch adds support for Analog Devices AD7923 ADC in the IIO Subsystem.
>
> Signed-off-by: Patrick Vasseur <patrick.vasseur@....fr>
> Signed-off-by: Christophe Leroy <christophe.leroy@....fr>
Hi,
Thanks for the driver, looks pretty good. Some comments inline.
- Lars
>
> diff -uN linux-3.7.1/drivers/staging/iio/adc/Kconfig linux/drivers/staging/iio/adc/Kconfig
> --- linux-3.7.1/drivers/staging/iio/adc/Kconfig 2012-12-17 20:14:54.000000000 +0100
> +++ linux/drivers/staging/iio/adc/Kconfig 2012-12-13 19:52:10.000000000 +0100
New IIO drivers should not be added to staging, unless there is a very good
reason. Since this driver does not have any major issues it should directly go
into drivers/iio/
[...]
> diff -uN linux-3.7.1/drivers/staging/iio/adc/ad7923.h linux/drivers/staging/iio/adc/ad7923.h
> --- linux-3.7.1/drivers/staging/iio/adc/ad7923.h 1970-01-01 01:00:00.000000000 +0100
> +++ linux/drivers/staging/iio/adc/ad7923.h 2013-01-05 17:53:53.000000000 +0100
> @@ -0,0 +1,72 @@
> +/*
> + * AD7923 SPI ADC driver
> + *
> + * Copyright 2011 Analog Devices Inc (from AD7298 Driver)
> + * Copyright 2012 CS Systemes d'Information
> + *
> + * Licensed under the GPL-2 or later.
> + */
> +#ifndef IIO_ADC_AD7923_H_
> +#define IIO_ADC_AD7923_H_
> +
> +#define AD7923_WRITE_CR (1 << 11) /* write control register */
> +#define AD7923_RANGE (1 << 1) /* range to REFin */
> +#define AD7923_CODING (1 << 0) /* coding is straight binary */
> +#define AD7923_PM_MODE_AS (1) /* auto shutdown */
> +#define AD7923_PM_MODE_FS (2) /* full shutdown */
> +#define AD7923_PM_MODE_OPS (3) /* normal operation */
> +#define AD7923_CHANNEL_0 (0) /* analog input 0 */
> +#define AD7923_CHANNEL_1 (1) /* analog input 1 */
> +#define AD7923_CHANNEL_2 (2) /* analog input 2 */
> +#define AD7923_CHANNEL_3 (3) /* analog input 3 */
> +#define AD7923_SEQUENCE_OFF (0) /* no sequence fonction */
> +#define AD7923_SEQUENCE_PROTECT (2) /* no interrupt write cycle */
> +#define AD7923_SEQUENCE_ON (3) /* continuous sequence */
> +
> +#define AD7923_MAX_CHAN 4
> +
> +#define AD7923_PM_MODE_WRITE(mode) (mode << 4) /* write mode */
> +#define AD7923_CHANNEL_WRITE(channel) (channel << 6) /* write channel */
> +#define AD7923_SEQUENCE_WRITE(sequence) (((sequence & 1) << 3) \
> + + ((sequence & 2) << 9))
> + /* write sequence fonction */
> +/* left shift for CR : bit 11 transmit in first */
> +#define AD7923_SHIFT_REGISTER 4
> +
> +/* val = value, dec = left shift, bits = number of bits of the mask */
> +#define EXTRACT(val, dec, bits) ((val >> dec) & ((1 << bits) - 1))
> +/* val = value, bits = number of bits of the original value */
> +#define EXTRACT_PERCENT(val, bits) (((val + 1) * 100) >> bits)
> +
> +struct ad7923_state {
> + struct spi_device *spi;
> + struct regulator *reg;
> + struct spi_transfer ring_xfer[6];
> + struct spi_transfer scan_single_xfer[2];
> + struct spi_message ring_msg;
> + struct spi_message scan_single_msg;
> + /*
> + * DMA (thus cache coherency maintenance) requires the
> + * transfer buffers to live in their own cache lines.
> + */
> + unsigned short rx_buf[4] ____cacheline_aligned;
> + unsigned short tx_buf[2];
both buffers should of type __be16
> +};
> +
> +#ifdef CONFIG_IIO_BUFFER
> +int ad7923_register_ring_funcs_and_init(struct iio_dev *indio_dev);
> +void ad7923_ring_cleanup(struct iio_dev *indio_dev);
> +int ad7923_update_scan_mode(struct iio_dev *indio_dev,
> + const unsigned long *active_scan_mask);
> +#else /* CONFIG_IIO_BUFFER */
> +static inline int
> +ad7923_register_ring_funcs_and_init(struct iio_dev *indio_dev)
> +{
> + return 0;
> +}
> +static inline void ad7923_ring_cleanup(struct iio_dev *indio_dev)
> +{
> +}
> +#define ad7923_update_scan_mode NULL
> +#endif /* CONFIG_IIO_BUFFER */
> +#endif /* IIO_ADC_AD7923_H_ */
> diff -uN linux-3.7.1/drivers/staging/iio/adc/ad7923_core.c linux/drivers/staging/iio/adc/ad7923_core.c
> --- linux-3.7.1/drivers/staging/iio/adc/ad7923_core.c 1970-01-01 01:00:00.000000000 +0100
> +++ linux/drivers/staging/iio/adc/ad7923_core.c 2013-01-05 17:54:11.000000000 +0100
> @@ -0,0 +1,202 @@
> +/*
> + * AD7923 SPI ADC driver
> + *
> + * Copyright 2011 Analog Devices Inc (from AD7298 Driver)
> + * Copyright 2012 CS Systemes d'Information
> + *
> + * Licensed under the GPL-2.
> + */
> +
> +#include <linux/device.h>
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/sysfs.h>
> +#include <linux/spi/spi.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/err.h>
> +#include <linux/module.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +#include <linux/iio/buffer.h>
> +
> +#include "ad7923.h"
> +
> +#define AD7923_V_CHAN(index) \
> + { \
> + .type = IIO_VOLTAGE, \
> + .indexed = 1, \
> + .channel = index, \
> + .info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT | \
> + IIO_CHAN_INFO_SCALE_SHARED_BIT, \
> + .address = index, \
> + .scan_index = index, \
> + .scan_type = { \
> + .sign = 'u', \
> + .realbits = 12, \
> + .storagebits = 16, \
> + }, \
> + }
> +
> +static struct iio_chan_spec ad7923_channels[] = {
static const struct
> + AD7923_V_CHAN(0),
> + AD7923_V_CHAN(1),
> + AD7923_V_CHAN(2),
> + AD7923_V_CHAN(3),
> + IIO_CHAN_SOFT_TIMESTAMP(4),
> +};
> +
[...]
> +
> +static int ad7923_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val,
> + int *val2,
> + long m)
> +{
> + int ret;
> + struct ad7923_state *st = iio_priv(indio_dev);
> +
> + switch (m) {
> + case IIO_CHAN_INFO_RAW:
> + mutex_lock(&indio_dev->mlock);
> + if (iio_buffer_enabled(indio_dev))
> + ret = -EBUSY;
> + else
> + ret = ad7923_scan_direct(st, chan->address);
> + mutex_unlock(&indio_dev->mlock);
> +
> + if (ret < 0)
> + return ret;
> + if (chan->address == EXTRACT(ret, 12, 4)) {
> + *val = EXTRACT(ret, 0, 12);
> + *val2 = EXTRACT_PERCENT(*val, 12);
val2 is never used in the upper layers in this case.
> + }
If the address does not match you should probably return an error
> + return IIO_VAL_INT;
> + }
How about also reporting the scale attribute?
> + return -EINVAL;
> +}
> +
> +static const struct iio_info ad7923_info = {
> + .read_raw = &ad7923_read_raw,
> + .update_scan_mode = ad7923_update_scan_mode,
> + .driver_module = THIS_MODULE,
> +};
> +
> +static int __devinit ad7923_probe(struct spi_device *spi)
__devinit/__devexit is being phased out in upstream, it should not be used in
new drivers anymore.
> +{
> + struct ad7923_state *st;
> + struct device *dev = &spi->dev;
> + int ret;
> + struct iio_dev *indio_dev = iio_device_alloc(sizeof(*st));
> +
> + if (indio_dev == NULL)
> + return -ENOMEM;
> +
> + st = iio_priv(indio_dev);
> +
> + st->reg = regulator_get(&spi->dev, "vcc");
> + if (!IS_ERR(st->reg)) {
If the regulator could not be requested return an error.
> + ret = regulator_enable(st->reg);
> + if (ret)
> + goto error_put_reg;
> + }
> +
> + spi_set_drvdata(spi, indio_dev);
> +
> + st->spi = spi;
> +
> + indio_dev->name = spi_get_device_id(spi)->name;
> + indio_dev->dev.parent = &spi->dev;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->channels = ad7923_channels;
> + indio_dev->num_channels = ARRAY_SIZE(ad7923_channels);
> + indio_dev->info = &ad7923_info;
> +
> + /* Setup default message */
> + st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
> + st->scan_single_xfer[0].len = 2;
> + st->scan_single_xfer[0].cs_change = 1;
> + st->scan_single_xfer[1].rx_buf = &st->rx_buf[0];
> + st->scan_single_xfer[1].len = 2;
> +
> + spi_message_init(&st->scan_single_msg);
> + spi_message_add_tail(&st->scan_single_xfer[0], &st->scan_single_msg);
> + spi_message_add_tail(&st->scan_single_xfer[1], &st->scan_single_msg);
> +
> + ret = ad7923_register_ring_funcs_and_init(indio_dev);
> + if (ret)
> + goto error_disable_reg;
> +
> + ret = iio_device_register(indio_dev);
> + if (ret)
> + goto error_cleanup_ring;
> +
> + dev_info(dev, "Driver AD7923 is added.\n");
This line is just noise, please remove it.
> +
> + return 0;
> +
> +error_cleanup_ring:
> + ad7923_ring_cleanup(indio_dev);
> +error_disable_reg:
> + if (!IS_ERR(st->reg))
> + regulator_disable(st->reg);
> +error_put_reg:
> + if (!IS_ERR(st->reg))
> + regulator_put(st->reg);
> + iio_device_free(indio_dev);
> +
> + return ret;
> +}
> +
> +static int __devexit ad7923_remove(struct spi_device *spi)
> +{
> + struct iio_dev *indio_dev = spi_get_drvdata(spi);
> + struct ad7923_state *st = iio_priv(indio_dev);
> +
> + iio_device_unregister(indio_dev);
> + ad7923_ring_cleanup(indio_dev);
> + if (!IS_ERR(st->reg)) {
> + regulator_disable(st->reg);
> + regulator_put(st->reg);
> + }
> + iio_device_free(indio_dev);
> +
> + return 0;
> +}
> +
> +static const struct spi_device_id ad7923_id[] = {
> + {"ad7923", 0},
> + {}
> +};
> +MODULE_DEVICE_TABLE(spi, ad7923_id);
> +
> +static struct spi_driver ad7923_driver = {
> + .driver = {
> + .name = "ad7923",
> + .owner = THIS_MODULE,
> + },
> + .probe = ad7923_probe,
> + .remove = __devexit_p(ad7923_remove),
> + .id_table = ad7923_id,
> +};
> +module_spi_driver(ad7923_driver);
> +
> +MODULE_AUTHOR("Patrick Vasseur <patrick.vasseur@....fr>");
> +MODULE_DESCRIPTION("Analog Devices AD7923 ADC");
> +MODULE_LICENSE("GPL v2");
> diff -uN linux-3.7.1/drivers/staging/iio/adc/ad7923_ring.c linux/drivers/staging/iio/adc/ad7923_ring.c
> --- linux-3.7.1/drivers/staging/iio/adc/ad7923_ring.c 1970-01-01 01:00:00.000000000 +0100
> +++ linux/drivers/staging/iio/adc/ad7923_ring.c 2013-01-05 17:51:47.000000000 +0100
Considering the overall size of the driver I think it makes sense to put it all
in just one file.
> @@ -0,0 +1,113 @@
> +/*
> + * AD7923 SPI ADC driver
> + *
> + * Copyright 2011 Analog Devices Inc (from AD7298 Driver)
> + * Copyright 2012 CS Systemes d'Information
> + *
> + * Licensed under the GPL-2.
> + */
> +
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/spi/spi.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/iio/triggered_buffer.h>
> +
> +#include "ad7923.h"
> +
> +/**
> + * ad7923_update_scan_mode() setup the spi transfer buffer for the new scan mask
> + **/
> +int ad7923_update_scan_mode(struct iio_dev *indio_dev,
> + const unsigned long *active_scan_mask)
> +{
> + struct ad7923_state *st = iio_priv(indio_dev);
> + int i, cmd, channel;
> + int scan_count;
> +
> + /* Now compute overall size */
> + for (i = 0, channel = 0; i < AD7923_MAX_CHAN; i++)
> + if (test_bit(i, active_scan_mask))
> + channel = i;
> +
> + cmd = AD7923_WRITE_CR | AD7923_CODING | AD7923_RANGE |
> + AD7923_PM_MODE_WRITE(AD7923_PM_MODE_OPS) |
> + AD7923_SEQUENCE_WRITE(AD7923_SEQUENCE_ON) |
> + AD7923_CHANNEL_WRITE(channel);
Hm, ok this looks a bit strange. You lookup the first channel which is selected
and then also sample all channels which come before it. E.g. if only channel 2
is selected you sample channel 0, 1 and 2. In the trigger handler you push the
buffer to the IIO core. But in your buffer you have the result of channel 0 in
the position where IIO would expect channel 2.
I think it is better if you send a cmd for each channel that needs to be
samples. E.g.:
if (for_each_set_bit(i, active_scan_mask, AD7923_MAX_CHAN)) {
cmd = AD7923_WRITE_CR | AD7923_CODING | AD7923_RANGE |
AD7923_PM_MODE_WRITE(AD7923_PM_MODE_OPS) |
AD7923_SEQUENCE_WRITE(AD7923_SEQUENCE_OFF) |
AD7923_CHANNEL_WRITE(i);
cmd <<= AD7923_SHIFT_REGISTER;
st->tx_buf[j++] = cpu_to_be16(cmd);
}
> + cmd <<= AD7923_SHIFT_REGISTER;
> + st->tx_buf[0] = cpu_to_be16(cmd);
> +
> + /* build spi ring message */
> + st->ring_xfer[0].tx_buf = &st->tx_buf[0];
> + st->ring_xfer[0].len = 2;
> + st->ring_xfer[0].cs_change = 1;
> +
> + spi_message_init(&st->ring_msg);
> + spi_message_add_tail(&st->ring_xfer[0], &st->ring_msg);
> +
> + for (i = 0; i < (channel + 1); i++) {
> + st->ring_xfer[i + 1].rx_buf = &st->rx_buf[i];
> + st->ring_xfer[i + 1].len = 2;
> + st->ring_xfer[i + 1].cs_change = 1;
> + spi_message_add_tail(&st->ring_xfer[i + 1], &st->ring_msg);
> + }
> + /* make sure last transfer cs_change is not set */
> + st->ring_xfer[i + 1].cs_change = 0;
> +
> + return 0;
> +}
> +
> +/**
> + * ad7923_trigger_handler() bh of trigger launched polling to ring buffer
> + *
> + * Currently there is no option in this driver to disable the saving of
> + * timestamps within the ring.
> + **/
> +static irqreturn_t ad7923_trigger_handler(int irq, void *p)
> +{
> + struct iio_poll_func *pf = p;
> + struct iio_dev *indio_dev = pf->indio_dev;
> + struct ad7923_state *st = iio_priv(indio_dev);
> + s64 time_ns = 0;
> + __u16 buf[16];
> + int b_sent, i, channel;
> +
> + b_sent = spi_sync(st->spi, &st->ring_msg);
> + if (b_sent)
> + goto done;
> +
> + if (indio_dev->scan_timestamp) {
> + time_ns = iio_get_time_ns();
> + memcpy((u8 *)buf + indio_dev->scan_bytes - sizeof(s64),
> + &time_ns, sizeof(time_ns));
> + }
> +
> + for (i = 0, channel = 0; i < AD7923_MAX_CHAN; i++)
> + if (test_bit(i, indio_dev->active_scan_mask))
> + channel = i;
> +
> + for (i = 0; i < (channel + 1); i++)
> + buf[i] = be16_to_cpu(st->rx_buf[i]);
No need to perform the endianness conversion here. Just mark the channel as IIO_BE.
> +
> + iio_push_to_buffer(indio_dev->buffer, (u8 *)buf);
> +
> +done:
> + iio_trigger_notify_done(indio_dev->trig);
> +
> + return IRQ_HANDLED;
> +}
> +
[...]
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