Re: [PATCH v5 1/1] Add Microchip MCP3422/3/4 high resolution ADC

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



> I think this patch is more or less in it's final shape, please review it.

comments inline

> ---
>  drivers/iio/adc/Kconfig   |   10 ++
>  drivers/iio/adc/Makefile  |    1 +
>  drivers/iio/adc/mcp3422.c |  432 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 443 insertions(+)
>  create mode 100644 drivers/iio/adc/mcp3422.c
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index f725b45..e9879e6 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -145,6 +145,16 @@ config MCP320X
>  	  This driver can also be built as a module. If so, the module will be
>  	  called mcp320x.
>  
> +config MCP3422
> +	tristate "Microchip Technology MCP3422/3/4 driver"
> +	depends on I2C
> +	help
> +	  Say yes here to build support for Microchip Technology's MCP3422,
> +	  MCP3423 or MCP3424 analog to digital converters.
> +
> +	  This driver can also be built as a module. If so, the module will be
> +	  called mcp3422.
> +
>  config NAU7802
>  	tristate "Nuvoton NAU7802 ADC driver"
>  	depends on I2C
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 2a4324e..9772e3b 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -16,6 +16,7 @@ obj-$(CONFIG_EXYNOS_ADC) += exynos_adc.o
>  obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
>  obj-$(CONFIG_MAX1363) += max1363.o
>  obj-$(CONFIG_MCP320X) += mcp320x.o
> +obj-$(CONFIG_MCP3422) += mcp3422.o
>  obj-$(CONFIG_NAU7802) += nau7802.o
>  obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
>  obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
> diff --git a/drivers/iio/adc/mcp3422.c b/drivers/iio/adc/mcp3422.c
> new file mode 100644
> index 0000000..eda5d39
> --- /dev/null
> +++ b/drivers/iio/adc/mcp3422.c
> @@ -0,0 +1,432 @@
> +/*
> + * mcp3422.c - driver for the Microchip mcp3422/3/4 chip family
> + *
> + * Copyright (C) 2013, Angelo Compagnucci
> + * Author: Angelo Compagnucci <angelo.compagnucci@xxxxxxxxx>
> + *
> + * Datasheet: http://ww1.microchip.com/downloads/en/devicedoc/22088b.pdf
> + *
> + * This driver exports the value of analog input voltage to sysfs, the
> + * voltage unit is nV.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/module.h>
> +#include <linux/delay.h>
> +#include <linux/sysfs.h>
> +#include <linux/string.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/sysfs.h>
> +
> +/* Masks */
> +#define MCP3422_CHANNEL_MASK	0x60
> +#define MCP3422_PGA_MASK	0x03
> +#define MCP3422_SRATE_MASK	0x0C
> +#define MCP3422_SRATE_240	0x0
> +#define MCP3422_SRATE_60	0x1
> +#define MCP3422_SRATE_15	0x2
> +#define MCP3422_SRATE_3	0x3
> +#define MCP3422_PGA_1	0
> +#define MCP3422_PGA_2	1
> +#define MCP3422_PGA_4	2
> +#define MCP3422_PGA_8	3
> +#define MCP3422_CONT_SAMPLING	0x10
> +
> +#define MCP3422_CHANNEL(config)	((((config) & MCP3422_CHANNEL_MASK) >> 5) + 1)
> +#define MCP3422_PGA(config)	((config) & MCP3422_PGA_MASK)
> +#define MCP3422_SAMPLE_RATE(config)	(((config) & MCP3422_SRATE_MASK) >> 2)
> +
> +#define MCP3422_CHANNEL_VALUE(value) (((value - 1) << 5) & MCP3422_CHANNEL_MASK)
> +#define MCP3422_PGA_VALUE(value) ((value) & MCP3422_PGA_MASK)
> +#define MCP3422_SAMPLE_RATE_VALUE(value) ((value << 2) & MCP3422_SRATE_MASK)
> +
> +#define MCP3422_CHAN(index) \
> +	{ \
> +		.type = IIO_VOLTAGE, \
> +		.indexed = 1, \
> +		.channel = index, \
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) \
> +				| BIT(IIO_CHAN_INFO_SCALE), \
> +	}
> +
> +/* LSB is in nV to eliminate floating point */
> +static const u32 rates_to_lsb[] = {1000000, 250000, 62500, 15625};
> +
> +/* Client data (each client gets its own) */
> +struct mcp3422 {
> +	struct i2c_client *i2c;
> +	u8 config;
> +	u8 pga[4];
> +	struct mutex lock;
> +};
> +
> +static int mcp3422_update_config(struct mcp3422 *adc, u8 newconfig)
> +{
> +	int ret;
> +
> +	mutex_lock(&adc->lock);
> +
> +	ret = i2c_master_send(adc->i2c, &newconfig, 1);
> +	if (ret > 0)
> +		adc->config = newconfig;
> +
> +	mutex_unlock(&adc->lock);
> +
> +	return ret;
> +}
> +
> +static int mcp3422_read(struct mcp3422 *adc, int *value, u8 *config)
> +{
> +	int ret = 0;
> +	u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
> +	u8 buf[4] = {0, 0, 0, 0};
> +	u32 temp;
> +
> +	if (sample_rate == MCP3422_SRATE_3) {
> +		ret = i2c_master_recv(adc->i2c, buf, 4);
> +		temp = buf[0] << 16 | buf[1] << 8 | buf[2];
> +		*config = buf[3];
> +	} else {
> +		ret = i2c_master_recv(adc->i2c, buf, 3);
> +		temp = buf[0] << 8 | buf[1];
> +		*config = buf[2];
> +	}
> +
> +	switch (sample_rate) {
> +	case MCP3422_SRATE_240:
> +		*value = sign_extend32(temp, 12);
> +		break;
> +	case MCP3422_SRATE_60:
> +		*value = sign_extend32(temp, 14);
> +		break;
> +	case MCP3422_SRATE_15:
> +		*value = sign_extend32(temp, 16);
> +		break;
> +	case MCP3422_SRATE_3:
> +		*value = sign_extend32(temp, 18);
> +		break;
> +	}
> +
> +	return ret;
> +}
> +
> +static int mcp3422_read_channel(struct mcp3422 *adc,
> +				struct iio_chan_spec const *channel, int *value)
> +{
> +	int mtime = 0;
> +	u8 config = 0;
> +	u8 req_channel = channel->channel;
> +
> +	if (req_channel != MCP3422_CHANNEL(adc->config)) {
> +		config = adc->config;
> +		config &= ~MCP3422_CHANNEL_MASK;
> +		config |= MCP3422_CHANNEL_VALUE(req_channel);
> +		config &= ~MCP3422_PGA_MASK;
> +		config |= MCP3422_PGA_VALUE(adc->pga[req_channel-1]);
> +		mcp3422_update_config(adc, config);
> +		switch (MCP3422_SAMPLE_RATE(config)) {
> +		case MCP3422_SRATE_240:
> +			mtime = 1000 / 240;
> +			break;
> +		case MCP3422_SRATE_60:
> +			mtime = 1000 / 60;
> +			break;
> +		case MCP3422_SRATE_15:
> +			mtime = 1000 / 15;
> +			break;
> +		case MCP3422_SRATE_3:
> +			mtime = 1000 / 3;
> +			break;
> +		}
> +		msleep(mtime);
> +	}
> +
> +	return mcp3422_read(adc, value, &config);
> +}
> +
> +static int mcp3422_read_raw(struct iio_dev *iio,
> +			struct iio_chan_spec const *channel, int *val1,
> +			int *val2, long mask)
> +{
> +	struct mcp3422 *adc = iio_priv(iio);
> +	int err, temp = 0;
> +
> +	u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
> +	u8 pga		 = MCP3422_PGA(adc->config);
> +
> +	err = mcp3422_read_channel(adc, channel, &temp);
> +	if (err < 0)
> +		return err;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		*val1 = temp;
> +
> +		return IIO_VAL_INT;
> +
> +	case IIO_CHAN_INFO_SCALE:
> +
> +		temp = (temp * rates_to_lsb[sample_rate])
> +			/ (pga ? 1 << pga : 1);
> +
> +		*val1 = temp / 1000000000;
> +		*val2 = temp % 1000000000;
> +
> +		return IIO_VAL_INT_PLUS_NANO;
> +
> +	default:
> +		break;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int mcp3422_write_raw(struct iio_dev *iio,
> +			struct iio_chan_spec const *channel, int val1,
> +			int val2, long mask)
> +{
> +	struct mcp3422 *adc = iio_priv(iio);
> +	u8 pga, config;
> +	u8 req_channel = channel->channel;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (val1) {
> +		case 1:
> +			pga = MCP3422_PGA_1;
> +			break;
> +		case 2:
> +			pga = MCP3422_PGA_2;
> +			break;
> +		case 4:
> +			pga = MCP3422_PGA_4;
> +			break;
> +		case 8:
> +			pga = MCP3422_PGA_8;
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +		mutex_lock(&adc->lock);
> +
> +		config = adc->config;
> +		adc->pga[req_channel-1] = pga;
> +
> +		mutex_unlock(&adc->lock);

I don't understand the locking logic?
what should be protected?

> +
> +		config &= ~MCP3422_CHANNEL_MASK;
> +		config |= MCP3422_CHANNEL_VALUE(req_channel);
> +		config &= ~MCP3422_PGA_MASK;
> +		config |= MCP3422_PGA_VALUE(adc->pga[req_channel-1]);
> +		mcp3422_update_config(adc, config);
> +		return 0;
> +	default:
> +		break;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static ssize_t mcp3422_set_sample_rate(struct device *dev,
> +		struct device_attribute *attr,
> +		const char *buf, size_t count)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct iio_dev *iio = i2c_get_clientdata(client);
> +	struct mcp3422 *adc = iio_priv(iio);
> +	u8 value = 0;

no need to init value

> +	u8 config = adc->config;
> +
> +	if (kstrtou8(buf, 10, &value) < 0)
> +		return -EINVAL;
> +
> +	switch (value) {
> +	case 240:
> +		value = MCP3422_SRATE_240;
> +		break;
> +	case 60:
> +		value = MCP3422_SRATE_60;
> +		break;
> +	case 15:
> +		value = MCP3422_SRATE_15;
> +		break;
> +	case 3:
> +		value = MCP3422_SRATE_3;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	config &= ~MCP3422_SRATE_MASK;
> +	config |= MCP3422_SAMPLE_RATE_VALUE(value);
> +
> +	mcp3422_update_config(adc, config);
> +
> +	return count;
> +}
> +
> +static ssize_t mcp3422_get_sample_rate(struct device *dev,
> +		struct device_attribute *attr,
> +		char *buf)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct iio_dev *iio = i2c_get_clientdata(client);
> +	struct mcp3422 *adc = iio_priv(iio);
> +	u8 value = 0;
> +
> +	switch (MCP3422_SAMPLE_RATE(adc->config)) {
> +	case MCP3422_SRATE_240:
> +		value = 240;
> +		break;
> +	case MCP3422_SRATE_60:
> +		value = 60;
> +		break;
> +	case MCP3422_SRATE_15:
> +		value = 15;
> +		break;
> +	case MCP3422_SRATE_3:
> +		value = 3;
> +		break;
> +	}
> +
> +	return sprintf(buf, "%d\n", value);
> +}
> +
> +static IIO_DEV_ATTR_SAMP_FREQ(S_IRUGO | S_IWUSR,
> +			mcp3422_get_sample_rate,
> +			mcp3422_set_sample_rate);
> +static IIO_CONST_ATTR(sampling_frequency_available, "240 60 15 3");

sample rate should be exposed IIO_CHAN_INFO_SAMP_FREQ

> +static IIO_CONST_ATTR(scale_available, "1 2 4 8");
> +
> +static struct attribute *mcp3422_attributes[] = {
> +	&iio_dev_attr_sampling_frequency.dev_attr.attr,
> +	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
> +	&iio_const_attr_scale_available.dev_attr.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group mcp3422_attribute_group = {
> +	.attrs = mcp3422_attributes,
> +};
> +
> +static const struct iio_chan_spec mcp3422_channels[] = {
> +	MCP3422_CHAN(1),

channels are indexed starting from 0 generally

> +	MCP3422_CHAN(2),
> +};
> +
> +static const struct iio_chan_spec mcp3424_channels[] = {
> +	MCP3422_CHAN(1),
> +	MCP3422_CHAN(2),
> +	MCP3422_CHAN(3),
> +	MCP3422_CHAN(4),
> +};
> +
> +static const struct iio_info mcp3422_info = {
> +	.read_raw = mcp3422_read_raw,
> +	.write_raw = mcp3422_write_raw,
> +	.attrs = &mcp3422_attribute_group,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +static int mcp3422_probe(struct i2c_client *client,
> +			 const struct i2c_device_id *id)
> +{
> +	struct iio_dev *indio_dev;
> +	struct mcp3422 *adc;
> +	int err;
> +	u8 config;
> +
> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
> +		return -ENODEV;
> +
> +	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*adc));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	adc = iio_priv(indio_dev);
> +	adc->i2c = client;
> +	memset(&adc->pga, 0, 4);

memset() not needed 

> +
> +	mutex_init(&adc->lock);
> +
> +	indio_dev->dev.parent = &client->dev;
> +	indio_dev->name = dev_name(&client->dev);
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->info = &mcp3422_info;
> +
> +	switch ((unsigned int)(id->driver_data)) {
> +	case 2:
> +	case 3:
> +		indio_dev->channels = mcp3422_channels;
> +		indio_dev->num_channels = ARRAY_SIZE(mcp3422_channels);
> +		break;
> +	case 4:
> +		indio_dev->channels = mcp3424_channels;
> +		indio_dev->num_channels = ARRAY_SIZE(mcp3424_channels);
> +		break;
> +	}
> +
> +	err = iio_device_register(indio_dev);
> +	if (err < 0)
> +		return err;
> +
> +	i2c_set_clientdata(client, indio_dev);
> +
> +	/* meaningful default configuration */
> +	config = (MCP3422_CONT_SAMPLING
> +		| MCP3422_CHANNEL_VALUE(1)
> +		| MCP3422_PGA_VALUE(MCP3422_PGA_1)
> +		| MCP3422_SAMPLE_RATE_VALUE(MCP3422_SRATE_240));
> +	mcp3422_update_config(adc, config);

move this before register() to avoid a race window?

> +
> +	return 0;
> +}
> +
> +static int mcp3422_remove(struct i2c_client *client)
> +{
> +	struct iio_dev *iio = i2c_get_clientdata(client);
> +
> +	iio_device_unregister(iio);
> +	iio_device_free(iio);
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id mcp3422_id[] = {
> +	{ "mcp3422", 2 },
> +	{ "mcp3423", 3 },
> +	{ "mcp3424", 4 },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, mcp3422_id);
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id mcp3422_of_match[] = {
> +	{ .compatible = "mcp3422" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, mcp3422_of_match);
> +#endif
> +
> +static struct i2c_driver mcp3422_driver = {
> +	.driver = {
> +		.name = "mcp3422",
> +		.owner = THIS_MODULE,
> +		.of_match_table = of_match_ptr(mcp3422_of_match),
> +	},
> +	.probe = mcp3422_probe,
> +	.remove = mcp3422_remove,
> +	.id_table = mcp3422_id,
> +};
> +module_i2c_driver(mcp3422_driver);
> +
> +MODULE_AUTHOR("Angelo Compagnucci <angelo.compagnucci@xxxxxxxxx>");
> +MODULE_DESCRIPTION("Microchip mcp3422/3/4 driver");
> +MODULE_LICENSE("GPL v2");
> 

-- 

Peter Meerwald
+43-664-2444418 (mobile)
--
To unsubscribe from this list: send the line "unsubscribe linux-iio" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Input]     [Linux Kernel]     [Linux SCSI]     [X.org]

  Powered by Linux