Re: [PATCH 2/2] iio: adc: ti-ads1298: Add driver
From: Andy Shevchenko
Date: Wed Dec 13 2023 - 10:27:10 EST
On Wed, Dec 13, 2023 at 10:47:22AM +0100, Mike Looijmans wrote:
> Skeleton driver for the TI ADS1298 medical ADC. This device is
> typically used for ECG and similar measurements. Supports data
> acquisition at configurable scale and sampling frequency.
...
> +config TI_ADS1298
> + tristate "Texas Instruments ADS1298"
> + depends on SPI
> + select IIO_BUFFER
> + default y
Huh?!
> + help
> + If you say yes here you get support for Texas Instruments ADS1298
> + medical ADC chips
> +
> + This driver can also be built as a module. If so, the module will be
> + called ti-ads1298.
...
> +#include <linux/bitfield.h>
> +#include <linux/clk.h>
> +#include <linux/err.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/kernel.h>
Is it used as a proxy? (At least for array_size.h)
Please use real headers in such case.
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +#include <linux/sysfs.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/spi/spi.h>
This is interesting grouping, but okay, I understand the point.
> +#include <linux/iio/iio.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/kfifo_buf.h>
> +#include <linux/iio/sysfs.h>
...
> +#define ADS1298_CLK_RATE 2048000
Units? _HZ ?
...
> +/* Outputs status word and 8 samples of 24 bits each, plus the command byte */
/* Outputs status word and 8 24-bit samples, plus the command byte */
a bit shorter.
> +#define ADS1298_SPI_RDATA_BUFFER_SIZE ((ADS1298_MAX_CHANNELS + 1) * 3 + 1)
...
> +#define ADS1298_CHAN(index) \
> +{ \
> + .type = IIO_VOLTAGE, \
> + .indexed = 1, \
> + .channel = index, \
> + .address = 3 * index + 4, \
Hmm... does this 3 have a distinct definition?
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
> + BIT(IIO_CHAN_INFO_SCALE), \
Can be written as below
.info_mask_separate = \
BIT(IIO_CHAN_INFO_RAW) | \
BIT(IIO_CHAN_INFO_SCALE), \
> + .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
> + BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
.info_mask_shared_by_all = \
BIT(IIO_CHAN_INFO_SAMP_FREQ) | \
BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO), \
> + .scan_index = index, \
> + .scan_type = { \
> + .sign = 's', \
> + .realbits = 24, \
> + .storagebits = 32, \
> + .endianness = IIO_BE, \
> + }, \
> +}
...
> +static int ads1298_write_cmd(struct ads1298_private *priv, u8 command)
> +{
> + struct spi_transfer cmd_xfer = {
> + .tx_buf = priv->cmd_buffer,
> + .rx_buf = priv->cmd_buffer,
> + .len = 1,
sizeof(command) ?
> + .speed_hz = ADS1298_SPI_BUS_SPEED_SLOW,
> + .delay.value = 2,
> + .delay.unit = SPI_DELAY_UNIT_USECS,
.delay = {
.value = ...
.unit = ...
},
> + };
> + priv->cmd_buffer[0] = command;
> +
> + return spi_sync_transfer(priv->spi, &cmd_xfer, 1);
> +}
...
> + /* Cannot take longer than 40ms (250Hz) */
> + ret = wait_for_completion_timeout(&priv->completion,
> + msecs_to_jiffies(50));
One line?
> + if (!ret)
> + return -ETIMEDOUT;
...
> + if (cfg & ADS1298_MASK_CONFIG1_HR)
> + rate >>= 6; /* HR mode */
> + else
> + rate >>= 7; /* LP mode */
Are those magic numbers defined?
...
> + factor = (rate >> 6) / val;
Is it the same 6 semantically as above?
...
> + return IIO_VAL_FRACTIONAL_LOG2;
> +}
> +
> +
One blank line is enough.
> + *val = sign_extend32(get_unaligned_be24(
> + priv->rx_buffer + chan->address), 23);
Strange indentation.
*val = sign_extend32(get_unaligned_be24(priv->rx_buffer + chan->address),
23);
...
> + case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
> + ret = regmap_read(priv->regmap, ADS1298_REG_CONFIG1, val);
> + if (!ret) {
Why not using standard pattern?
if (ret)
return ret;
(see below)
> + ret = IIO_VAL_INT;
> + *val = (16 << (*val & ADS1298_MASK_CONFIG1_DR));
Outer parentheses are redundant.
> + }
> + break;
return IIO_VAL_INT;
> + default:
> + ret = -EINVAL;
> + break;
return directly.
> + }
> + return ret;
It will gone.
...
> +static int ads1298_write_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan, int val,
> + int val2, long mask)
> +{
> + struct ads1298_private *priv = iio_priv(indio_dev);
> + int ret;
No need, just return directly.
> + switch (mask) {
> + case IIO_CHAN_INFO_SAMP_FREQ:
> + ret = ads1298_set_samp_freq(priv, val);
> + break;
> + default:
> + ret = -EINVAL;
> + break;
> + }
> +
> + return ret;
> +}
...
> +static int ads1298_reg_access(struct iio_dev *indio_dev, unsigned int reg,
> + unsigned int writeval, unsigned int *readval)
> +{
> + struct ads1298_private *priv = iio_priv(indio_dev);
> + if (!readval)
Perhaps positive conditional?
if (readval)
return readval;
return writeval;
> + return regmap_write(priv->regmap, reg, writeval);
> +
> + return regmap_read(priv->regmap, reg, readval);
> +}
...
> + /* Power down channels that aren't in use */
> + for (i = 0; i < ADS1298_MAX_CHANNELS; i++) {
> + regmap_update_bits(priv->regmap, ADS1298_REG_CHnSET(i),
> + ADS1298_MASK_CH_PD,
> + test_bit(i, scan_mask) ?
> + 0 : ADS1298_MASK_CH_PD);
Broken indentation.
> + }
...
> +static void ads1298_rdata_unmark_busy(struct ads1298_private *priv)
> +{
> + unsigned long flags;
> +
> + /* Notify we're no longer waiting for the SPI transfer to complete */
> + spin_lock_irqsave(&priv->irq_busy_lock, flags);
> + priv->rdata_xfer_busy = false;
> + spin_unlock_irqrestore(&priv->irq_busy_lock, flags);
Perhaps switch to use guard()?
(And scoped_guard() where it makes sense.)
> +}
> + /* Transfer 24-bit value into 32-bit array */
> + memcpy(bounce + 1, data, 3);
Hmm... Wouldn't get_unaligned_..24() work here better?
> + bounce += 4;
If so, you can iterate over u32 members directly without this += 4.
...
> +static const char *ads1298_family_name(unsigned int id)
> +{
> + switch (id & 0xe0) {
GENMASK() ?
> + case 0x80:
> + return "ADS129x";
> + case 0xc0:
> + return "ADS129xR";
Can we have these all magics be defined?
> + default:
> + return "(unknown)";
> + }
> +}
...
> + if ((val & 0x18) == 0x10) {
Ditto.
> + dev_info(dev, "Found %s, %d channels\n",
> + ads1298_family_name(val),
> + 4 + 2 * (val & 0x07));
Ditto for 0x07.
> + } else {
> + dev_err(dev, "Unknown ID: 0x%x\n", val);
> + return -ENODEV;
> + }
...
> + indio_dev = devm_iio_device_alloc(dev, sizeof(*priv));
> + if (indio_dev == NULL)
We do !indio_dev in this case.
> + return -ENOMEM;
...
> + ret = devm_add_action_or_reset(dev, ads1298_reg_disable,
> + priv->reg_vref);
One line?
> + if (ret)
> + return ret;
...
> + return dev_err_probe(dev, PTR_ERR(priv->clk),
> + "Failed to get clk\n");
Ditto.
...
> + return dev_err_probe(dev, ret,
> + "Failed to enable avdd regulator\n");
Ditto.
...
> + ret = devm_add_action_or_reset(dev, ads1298_reg_disable,
> + priv->reg_avdd);
Ditto.
...
> + priv->regmap = devm_regmap_init(dev, NULL, priv,
> + &ads1298_regmap_config);
Ditto.
...
> + /* Avoid giving all the same name, iio scope doesn't handle that well */
IIO
> + indio_dev->name = devm_kasprintf(dev, GFP_KERNEL, "%s@%s",
> + spi_get_device_id(spi)->name,
> + dev_name(dev));
No error check?
> + if (reset_gpio) {
> + udelay(1); /* Minimum pulse width is 2 clocks at 2MHz */
How do you know it's 2MHz? Is it always the same on all platforms / setups?
> + gpiod_set_value(reset_gpio, 0);
> + } else {
> + ret = ads1298_write_cmd(priv, ADS1298_CMD_RESET);
> + if (ret)
> + return dev_err_probe(dev, ret, "RESET failed\n");
> + }
> + /* Wait 18 clock cycles for reset command to complete */
Ditto.
> + udelay(9);
...
> + ret = devm_request_irq(&spi->dev, spi->irq, &ads1298_interrupt,
&spi->dev is different to dev?
> + IRQF_TRIGGER_FALLING, indio_dev->name,
> + indio_dev);
...
> + ret = devm_iio_kfifo_buffer_setup(&spi->dev, indio_dev,
> + &ads1298_setup_ops);
Ditto.
...
> +static const struct spi_device_id ads1298_id[] = {
> + { "ads1298", },
Inner comma is not needed.
> + { }
> +};
...
> +static const struct of_device_id ads1298_of_table[] = {
> + { .compatible = "ti,ads1298" },
> + { },
Drop the comma in terminator entry.
> +};
--
With Best Regards,
Andy Shevchenko