Re: [PATCH v3 1/2] iio: Add driver for TLA202x ADCs

From: Jonathan Cameron
Date: Sat Mar 30 2019 - 12:00:39 EST

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In reply to: Jonathan Cameron: "Re: [PATCH v3 2/2] dt-bindings: iio: Add bindings for TI TLA202x ADCs"
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On Tue, 26 Mar 2019 14:56:19 +0100
Ibtsam Ul-Haq <ibtsam.haq.0x01@xxxxxxxxx> wrote:

> Basic driver for Texas Instruments TLA202x series ADCs. Input
> channels are configurable from the device tree. Input scaling
> is supported. Trigger buffer support is not yet implemented.
>
> Signed-off-by: Ibtsam Ul-Haq <ibtsam.haq.0x01@xxxxxxxxx>
Down to the nitpicks on this version so should be good for a v4.

Also probably some minor tweaks needed due to the discussion around
the dt binding.

Jonathan

> ---
> Changes in v3:
> - Added locking when setting SCALE
> - Removed deep-indented goto in read_raw
> - Other minor points mentioned in v2 review
> ---
> Changes in v2:
> - changed commit message
> - Added mutex to protect channel selection
> - Removed redundant mutex around i2c transfers
> - Removed PROCESSED channel output
> - Added SCALE info
> - Removed Continuous Mode since continuous read not supported
> - Removed SAMP_FREQ info since continuous read not supported
> ---
> ---
> drivers/iio/adc/Kconfig | 11 ++
> drivers/iio/adc/Makefile | 1 +
> drivers/iio/adc/ti-tla2024.c | 460 +++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 472 insertions(+)
> create mode 100644 drivers/iio/adc/ti-tla2024.c
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 5762565..8c214c8 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -816,6 +816,17 @@ config TI_AM335X_ADC
> To compile this driver as a module, choose M here: the module will be
> called ti_am335x_adc.
>
> +config TI_TLA2024
> + tristate "Texas Instruments TLA2024/TLA2022/TLA2021 ADC driver"
> + depends on OF
> + depends on I2C
> + help
> + Say yes here to build support for Texas Instruments TLA2024,
> + TLA2022 or TLA2021 I2C Analog to Digital Converters.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called ti-tla2024.
> +
> config TI_TLC4541
> tristate "Texas Instruments TLC4541 ADC driver"
> depends on SPI
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 9874e05..819f35b 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -75,6 +75,7 @@ obj-$(CONFIG_TI_ADS7950) += ti-ads7950.o
> obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
> obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
> obj-$(CONFIG_TI_TLC4541) += ti-tlc4541.o
> +obj-$(CONFIG_TI_TLA2024) += ti-tla2024.o
> obj-$(CONFIG_TWL4030_MADC) += twl4030-madc.o
> obj-$(CONFIG_TWL6030_GPADC) += twl6030-gpadc.o
> obj-$(CONFIG_VF610_ADC) += vf610_adc.o
> diff --git a/drivers/iio/adc/ti-tla2024.c b/drivers/iio/adc/ti-tla2024.c
> new file mode 100644
> index 0000000..f0eed4a
> --- /dev/null
> +++ b/drivers/iio/adc/ti-tla2024.c
> @@ -0,0 +1,460 @@
> +/* SPDX-License-Identifier: GPL-2.0
> + *
> + * Texas Instruments TLA2021/TLA2022/TLA2024 12-bit ADC driver
> + *
> + * Copyright (C) 2019 Koninklijke Philips N.V.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/iio/iio.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +
> +#define TLA2024_DATA 0x00
> +#define TLA2024_DATA_RES_MASK GENMASK(15, 4)
> +#define TLA2024_DATA_RES_SHIFT 4
> +
> +#define TLA2024_CONF 0x01
> +#define TLA2024_CONF_OS_MASK BIT(15)
> +#define TLA2024_CONF_OS_SHIFT 15
> +#define TLA2024_CONF_MUX_MASK GENMASK(14, 12)
> +#define TLA2024_CONF_MUX_SHIFT 12
> +#define TLA2024_CONF_PGA_MASK GENMASK(11, 9)
> +#define TLA2024_CONF_PGA_SHIFT 9
> +#define TLA2024_CONF_MODE_MASK BIT(8)
> +#define TLA2024_CONF_MODE_SHIFT 8
> +#define TLA2024_CONF_DR_MASK GENMASK(7, 5)
> +#define TLA2024_CONF_DR_SHIFT 5
> +
> +#define TLA2024_CONV_RETRY 10
> +
> +struct tla202x_model {
> + unsigned int mux_available;
> + unsigned int pga_available;
> +};
> +
> +struct tla2024 {
> + struct i2c_client *i2c;
> + struct tla202x_model *model;
> + struct mutex lock;
> + u8 used_mux_channels;
> +};
> +
> +struct tla2024_channel {
> + int ainp;
> + int ainn;
> + const char *datasheet_name;
> + bool differential;
> +};
> +
> +static const struct tla2024_channel tla2024_all_channels[] = {
> + {0, 1, "AIN0-AIN1", 1},
> + {0, 3, "AIN0-AIN3", 1},
> + {1, 3, "AIN1-AIN3", 1},
> + {2, 3, "AIN2-AIN3", 1},
> + {0, -1, "AIN0", 0},
> + {1, -1, "AIN1", 0},
> + {2, -1, "AIN2", 0},
> + {3, -1, "AIN3", 0},
> +};
> +
> +static int tla2024_find_chan_idx(u32 ainp_in, u32 ainn_in, u16 *idx)
> +{
> + u16 i;
> +
> + for (i = 0; i < ARRAY_SIZE(tla2024_all_channels); i++) {
> + if ((tla2024_all_channels[i].ainp == ainp_in) &&
> + (tla2024_all_channels[i].ainn == ainn_in)) {
> + *idx = i;
> + return 0;
> + }
> + }
> +
> + return -EINVAL;
> +}
> +
> +#define TLA202x_MODEL(_mux, _pga) \
> + { \
> + .mux_available = (_mux), \
> + .pga_available = (_pga), \
> + }
> +
> +enum tla2024_model_id {
> + TLA2021 = 0,
> + TLA2022 = 1,
> + TLA2024 = 2,
> +};
> +
> +static struct tla202x_model tla202x_models[] = {
> + [TLA2021] = TLA202x_MODEL(0, 0),
> + [TLA2022] = TLA202x_MODEL(0, 1),
> + [TLA2024] = TLA202x_MODEL(1, 1),
> +};
> +
> +static const int tla2024_scale[] = { /* scale, int plus micro */
> + 3, 0, 2, 0, 1, 0, 0, 500000, 0, 250000, 0, 125000 };
> +
> +static int tla2024_get(struct tla2024 *priv, u8 addr, u16 mask,
> + u16 shift, u16 *val)
> +{
> + int ret;
> + u16 data;
> +
> + ret = i2c_smbus_read_word_swapped(priv->i2c, addr);
> + if (ret < 0)
> + return ret;
> +
> + data = ret;
> + *val = (mask & data) >> shift;
> +
> + return 0;
> +}
> +
> +static int tla2024_set(struct tla2024 *priv, u8 addr, u16 mask,
> + u16 shift, u16 val)
> +{
> + int ret;
> + u16 data;
> +
> + ret = i2c_smbus_read_word_swapped(priv->i2c, addr);
> + if (ret < 0)
> + return ret;
> +
> + data = ret;
> + data &= ~mask;
> + data |= mask & (val << shift);
> +
> + ret = i2c_smbus_write_word_swapped(priv->i2c, addr, data);
> +
> + return ret;
> +}
> +
> +static int tla2024_read_avail(struct iio_dev *idev,
> + struct iio_chan_spec const *chan,
> + const int **vals, int *type, int *length,
> + long mask)
> +{
> + switch (mask) {
> + case IIO_CHAN_INFO_SCALE:
> +
> + *length = ARRAY_SIZE(tla2024_scale);
> + *vals = tla2024_scale;
> +
> + *type = IIO_VAL_INT_PLUS_MICRO;
> + return IIO_AVAIL_LIST;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static int tla2024_of_find_chan(struct tla2024 *priv, struct device_node *ch)
> +{
> + u16 chan_idx = 0;
> + u32 ainp, ainn;
> + int ret;
> +
> + ret = of_property_read_u32_index(ch, "single-channel", 0, &ainp);
> + if (ret) {
> + ret = of_property_read_u32_index(ch,
> + "diff-channels", 0, &ainp);
> + if (ret)
> + return ret;
> +
> + ret = of_property_read_u32_index(ch,
> + "diff-channels", 1, &ainn);
> + if (ret)
> + return ret;
> +
> + } else {
> + ainn = UINT_MAX;
> + }
> +
> + ret = tla2024_find_chan_idx(ainp, ainn, &chan_idx);
> + if (ret < 0)
> + return ret;
> +
> + /* if model doesn"t have mux then only channel 0 is allowed */
> + if (!priv->model->mux_available && chan_idx)
> + return -EINVAL;
> +
> + /* if already used */
> + if ((priv->used_mux_channels) & (1 << chan_idx))
> + return -EINVAL;
> +
> + return chan_idx;
> +}
> +
> +static int tla2024_init_chan(struct iio_dev *idev, struct device_node *node,
> + struct iio_chan_spec *chan)
> +{
> + struct tla2024 *priv = iio_priv(idev);
> + u16 chan_idx;
> + int ret;
> +
> + ret = tla2024_of_find_chan(priv, node);
> + if (ret < 0)
> + return ret;
> +
> + chan_idx = ret;
> + priv->used_mux_channels |= BIT(chan_idx);
> + chan->type = IIO_VOLTAGE;
> + chan->channel = tla2024_all_channels[chan_idx].ainp;
> + chan->channel2 = tla2024_all_channels[chan_idx].ainn;
> + chan->differential = tla2024_all_channels[chan_idx].differential;
> + chan->datasheet_name = tla2024_all_channels[chan_idx].datasheet_name;
> + chan->indexed = 1;
> + chan->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
> + chan->info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SCALE);
> + chan->info_mask_shared_by_all_available = BIT(IIO_CHAN_INFO_SCALE);
> +
> + return 0;
> +}
> +
> +static int tla2024_wait(struct tla2024 *priv)
> +{
> + int ret;
> + unsigned int retry = TLA2024_CONV_RETRY;
> + u16 status;
> +
> + do {
> + if (!--retry)
> + return -EIO;
> + ret = tla2024_get(priv, TLA2024_CONF, TLA2024_CONF_OS_MASK,
> + TLA2024_CONF_OS_SHIFT, &status);
> + if (ret < 0)
> + return ret;

> + if (!status)
> + usleep_range(25, 1000);
> + } while (!status);
> +
> + return ret;

return 0; It can't be anything else and get here (I think!)

> +}
> +
> +static int tla2024_singleshot_conv(struct tla2024 *priv,
> + struct iio_chan_spec const *chan, int *val)
> +{
> + int ret;
> + u32 ainp = chan->channel;
> + u32 ainn = chan->channel2;

Are these local variables worthwhile as value only used in one place?

> + u16 chan_id, data;
> + s16 tmp;
> +
> + ret = tla2024_set(priv, TLA2024_CONF, TLA2024_CONF_MODE_MASK,
> + TLA2024_CONF_MODE_SHIFT, 1);
> + if (ret < 0)
> + return ret;
> +
> + ret = tla2024_find_chan_idx(ainp, ainn, &chan_id);
> + if (ret < 0)
> + return ret;
> +
> + ret = tla2024_set(priv, TLA2024_CONF, TLA2024_CONF_MUX_MASK,
> + TLA2024_CONF_MUX_SHIFT, chan_id);
> + if (ret < 0)
> + return ret;
> +
> + ret = tla2024_set(priv, TLA2024_CONF, TLA2024_CONF_OS_MASK,
> + TLA2024_CONF_OS_SHIFT, 1);
> + if (ret < 0)
> + return ret;
> +
> + ret = tla2024_wait(priv);
> + if (ret < 0)
> + return ret;
> +
> + ret = tla2024_get(priv, TLA2024_DATA, TLA2024_DATA_RES_MASK,
> + TLA2024_DATA_RES_SHIFT, &data);
> + if (ret < 0)
> + return ret;
> +
> + tmp = (s16)(data << TLA2024_DATA_RES_SHIFT);
> + *val = tmp >> TLA2024_DATA_RES_SHIFT;
> + return IIO_VAL_INT;
> +}
> +
> +static int tla2024_set_scale(struct tla2024 *priv, int val, int val2)
> +{
> + int i;
> +
> + if (!(priv->model->pga_available))
> + return -EINVAL; /* scale can't be changed if no pga */
> +
> + for (i = 0; i < ARRAY_SIZE(tla2024_scale); i = i + 2) {
> + if ((tla2024_scale[i] == val) &&
> + (tla2024_scale[i + 1] == val2))
> + break;
> + }
> +
> + if (i == ARRAY_SIZE(tla2024_scale))
> + return -EINVAL;
> +
> + return tla2024_set(priv, TLA2024_CONF, TLA2024_CONF_PGA_MASK,
> + TLA2024_CONF_PGA_SHIFT, i >> 1);
> +}
> +
> +static int tla2024_get_scale(struct tla2024 *priv, int *val, int *val2)
> +{
> + u16 data;
> + int ret;
> +
> + if (!(priv->model->pga_available)) {
> + *val = 1; /* Scale always 1 mV when no PGA */
> + return IIO_VAL_INT;
> + }
> + ret = tla2024_get(priv, TLA2024_CONF, TLA2024_CONF_PGA_MASK,
> + TLA2024_CONF_PGA_SHIFT, &data);
> + if (ret < 0)
> + return ret;
> +
> + /* gain for the 3bit pga values 6 and 7 is same as at 5 */
> + if (data >= (ARRAY_SIZE(tla2024_scale) >> 1))
> + data = (ARRAY_SIZE(tla2024_scale) >> 1) - 1;
> +
> + *val = tla2024_scale[data << 1];
> + *val2 = tla2024_scale[(data << 1) + 1];

When doing indexes like this it's probably more readable to just use * 2
rather than the shift. The compiler should figure it out anyway.
Also / 2 is fine when can be evaluated at compile time as above.

> + return IIO_VAL_INT_PLUS_MICRO;
> +}
> +
> +static int tla2024_read_raw(struct iio_dev *idev,
> + struct iio_chan_spec const *channel, int *val,
> + int *val2, long mask)
> +{
> + struct tla2024 *priv = iio_priv(idev);
> + int ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_RAW:
> + mutex_lock(&priv->lock);
> + ret = tla2024_singleshot_conv(priv, channel, val);
> + mutex_unlock(&priv->lock);
> + return ret;
> +
> + case IIO_CHAN_INFO_SCALE:
> + return tla2024_get_scale(priv, val, val2);
> +
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static int tla2024_write_raw(struct iio_dev *idev,
> + struct iio_chan_spec const *chan,
> + int val, int val2, long mask)
> +{
> + struct tla2024 *priv = iio_priv(idev);
> + int ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_SCALE:
> + mutex_lock(&priv->lock);
> + ret = tla2024_set_scale(priv, val, val2);
> + mutex_unlock(&priv->lock);
> + return ret;
> + }
> +
> + return -EINVAL;
> +}
> +

The ordering of functions in here seems a little strange. I would
bring this together with the individual channel init code above
and not have it between the callbacks and the definition of the
struct iio_info below.

> +static int tla2024_of_chan_init(struct iio_dev *idev)
> +{
> + struct device_node *node = idev->dev.of_node;
> + struct device_node *child;
> + struct iio_chan_spec *channels;
> + int ret, i, num_channels;
> +
> + num_channels = of_get_available_child_count(node);
> + if (!num_channels) {
> + dev_err(&idev->dev, "no channels configured\n");
> + return -ENODEV;
> + }
> +
> + channels = devm_kcalloc(&idev->dev, num_channels,
> + sizeof(struct iio_chan_spec), GFP_KERNEL);
> + if (!channels)
> + return -ENOMEM;
> +
> + i = 0;
> + for_each_available_child_of_node(node, child) {
> + ret = tla2024_init_chan(idev, child, &channels[i]);
> + if (ret) {
> + of_node_put(child);
> + return ret;
> + }
> + i++;
> + }
> +
> + idev->channels = channels;
> + idev->num_channels = num_channels;
> +
> + return 0;
> +}
> +
> +static const struct iio_info tla2024_info = {
> + .read_raw = tla2024_read_raw,
> + .write_raw = tla2024_write_raw,
> + .read_avail = tla2024_read_avail,
> +};
> +
> +static int tla2024_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct iio_dev *iio;
> + struct tla2024 *priv;
> + int ret;
> +
> + if (!i2c_check_functionality(client->adapter,
> + I2C_FUNC_SMBUS_WORD_DATA))
> + return -EOPNOTSUPP;
> +
> + iio = devm_iio_device_alloc(&client->dev, sizeof(*priv));
> + if (!iio)
> + return -ENOMEM;
> +
> + priv = iio_priv(iio);
> + priv->i2c = client;
> + priv->model = &tla202x_models[id->driver_data];
> + mutex_init(&priv->lock);
> +
> + iio->dev.parent = &client->dev;
> + iio->dev.of_node = client->dev.of_node;
> + iio->name = client->name;
> + iio->modes = INDIO_DIRECT_MODE;
> + iio->info = &tla2024_info;
> +
> + ret = tla2024_of_chan_init(iio);
> + if (ret < 0)
> + return ret;
> +
> + return devm_iio_device_register(&client->dev, iio);
> +}
> +
> +static const struct i2c_device_id tla2024_id[] = {
> + { "tla2024", TLA2024 },
> + { "tla2022", TLA2022 },
> + { "tla2021", TLA2021 },
> + { }
> +};
> +MODULE_DEVICE_TABLE(i2c, tla2024_id);
> +
> +static const struct of_device_id tla2024_of_match[] = {
> + { .compatible = "ti,tla2024" },
> + { .compatible = "ti,tla2022" },
> + { .compatible = "ti,tla2021" },
> + { }
> +};
> +MODULE_DEVICE_TABLE(of, tla2024_of_match);
> +
> +static struct i2c_driver tla2024_driver = {
> + .driver = {
> + .name = "tla2024",
> + .of_match_table = of_match_ptr(tla2024_of_match),
> + },
> + .probe = tla2024_probe,
> + .id_table = tla2024_id,
> +};
> +module_i2c_driver(tla2024_driver);
> +
> +MODULE_AUTHOR("Ibtsam Haq <ibtsam.haq@xxxxxxxxxxx>");
> +MODULE_DESCRIPTION("Texas Instruments TLA2021/TLA2022/TLA2024 ADC driver");
> +MODULE_LICENSE("GPL v2");

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In reply to: Jonathan Cameron: "Re: [PATCH v3 2/2] dt-bindings: iio: Add bindings for TI TLA202x ADCs"
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