[PATCH v10] Add Microchip MCP3422/3/4 high resolution ADC

[PATCH v10] Add Microchip MCP3422/3/4 high resolution ADC

[Angelo Compagnucci]

Hi Jonathan,

Kawabonga! It works! Really, but really (no joke here!) thank you
for your precious support and sorry for not being so smart to
understand what you were saying me. Sorry again for being so pedantic!

I'm planning to write a tutorial based on my journey, something like
"Howto write your first IIO LDD", what do you think?

Attached here, there is the latest version of the patch based on jour suggestions.
I think all of your concerns are solved now.

Thank you again!

Signed-off-by: Angelo Compagnucci <angelo.compagnucci@gmail.com>
---
 drivers/iio/adc/Kconfig   |   10 +
 drivers/iio/adc/Makefile  |    1 +
 drivers/iio/adc/mcp3422.c |  409 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 420 insertions(+), 0 deletions(-)
 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..4598a54
--- /dev/null
+++ b/drivers/iio/adc/mcp3422.c
@@ -0,0 +1,409 @@
+/*
+ * mcp3422.c - driver for the Microchip mcp3422/3/4 chip family
+ *
+ * Copyright (C) 2013, Angelo Compagnucci
+ * Author: Angelo Compagnucci <angelo.compagnucci@gmail.com>
+ *
+ * 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/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)
+#define MCP3422_PGA(config)	((config) & MCP3422_PGA_MASK)
+#define MCP3422_SAMPLE_RATE(config)	(((config) & MCP3422_SRATE_MASK) >> 2)
+
+#define MCP3422_CHANNEL_VALUE(value) (((value) << 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), \
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
+	}
+
+/* LSB is in nV to eliminate floating point */
+static const u32 rates_to_lsb[] = {1000000, 250000, 62500, 15625};
+
+/*
+ *  scales calculated as:
+ *  rates_to_lsb[sample_rate] / (1 << pga);
+ *  pga is 1 for 0, 2
+ */
+
+static const int mcp3422_scales[4][4] = {
+	{ 1000000, 250000, 62500, 15625 },
+	{ 500000 , 125000, 31250, 7812 },
+	{ 250000 , 62500 , 15625, 3906 },
+	{ 125000 , 31250 , 7812 , 1953 } };
+
+/* Constant msleep times for data acquisitions */
+static const int mcp3422_read_times[4] = {
+	[MCP3422_SRATE_240] = 1000 / 240,
+	[MCP3422_SRATE_60] = 1000 / 60,
+	[MCP3422_SRATE_15] = 1000 / 15,
+	[MCP3422_SRATE_3] = 1000 / 3 };
+
+/* sample rates to integer conversion table */
+static const int mcp3422_sample_rates[4] = {
+	[MCP3422_SRATE_240] = 240,
+	[MCP3422_SRATE_60] = 60,
+	[MCP3422_SRATE_15] = 15,
+	[MCP3422_SRATE_3] = 3 };
+
+/* sample rates to sign extension table */
+static const int mcp3422_sign_extend[4] = {
+	[MCP3422_SRATE_240] = 12,
+	[MCP3422_SRATE_60] = 14,
+	[MCP3422_SRATE_15] = 16,
+	[MCP3422_SRATE_3] = 18 };
+
+/* 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;
+		ret = 0;
+	}
+
+	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];
+	}
+
+	*value = sign_extend32(temp, mcp3422_sign_extend[sample_rate]);
+
+	return ret;
+}
+
+static int mcp3422_read_channel(struct mcp3422 *adc,
+				struct iio_chan_spec const *channel, int *value)
+{
+	int ret;
+	u8 config;
+	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]);
+		ret = mcp3422_update_config(adc, config);
+		if (ret < 0)
+			return ret;
+		msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(adc->config)]);
+	}
+
+	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;
+
+	u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
+	u8 pga		 = MCP3422_PGA(adc->config);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		err = mcp3422_read_channel(adc, channel, val1);
+		if (err < 0)
+			return -EINVAL;
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+
+		*val1 = 0;
+		*val2 = mcp3422_scales[sample_rate][pga];
+		return IIO_VAL_INT_PLUS_NANO;
+
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		*val1 = mcp3422_sample_rates[MCP3422_SAMPLE_RATE(adc->config)]; 
+		return IIO_VAL_INT;
+
+	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 temp;
+	u8 config = adc->config;
+	u8 req_channel = channel->channel;
+	u8 sample_rate = MCP3422_SAMPLE_RATE(config);
+	u8 i;
+
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		if (val1 != 0)
+			return -EINVAL;
+
+		for (i = 0; i < ARRAY_SIZE(mcp3422_scales[0]); i++) {
+			if (val2 == mcp3422_scales[sample_rate][i]) {
+				adc->pga[req_channel] = i;
+				 
+				config &= ~MCP3422_CHANNEL_MASK;
+				config |= MCP3422_CHANNEL_VALUE(req_channel);
+				config &= ~MCP3422_PGA_MASK;
+				config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
+
+				return mcp3422_update_config(adc, config);
+			} 
+		}
+		return -EINVAL;
+
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		switch (val1) {
+		case 240:
+			temp = MCP3422_SRATE_240;
+			break;
+		case 60:
+			temp = MCP3422_SRATE_60;
+			break;
+		case 15:
+			temp = MCP3422_SRATE_15;
+			break;
+		case 3:
+			temp = MCP3422_SRATE_3;
+			break;
+		default:
+			return -EINVAL;
+		}
+
+		config &= ~MCP3422_CHANNEL_MASK;
+		config |= MCP3422_CHANNEL_VALUE(req_channel);
+		config &= ~MCP3422_SRATE_MASK;
+		config |= MCP3422_SAMPLE_RATE_VALUE(temp);
+
+		return mcp3422_update_config(adc, config);
+
+	default:
+		break;
+	}
+
+	return -EINVAL;
+}
+
+static int mcp3422_write_raw_get_fmt(struct iio_dev *indio_dev,
+		struct iio_chan_spec const *chan, long mask)
+{
+	switch (mask) {
+	case IIO_CHAN_INFO_SCALE:
+		return IIO_VAL_INT_PLUS_NANO;
+	case IIO_CHAN_INFO_SAMP_FREQ:
+		return IIO_VAL_INT_PLUS_MICRO;
+	default:
+		return -EINVAL;
+	}
+}
+
+static ssize_t mcp3422_show_scales(struct device *dev, 
+		struct device_attribute *attr, char *buf)
+{
+	struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));
+	u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
+
+	return sprintf(buf, "0.%09u 0.%09u 0.%09u 0.%09u\n",
+		mcp3422_scales[sample_rate][0],
+		mcp3422_scales[sample_rate][1],
+		mcp3422_scales[sample_rate][2],
+		mcp3422_scales[sample_rate][3]);
+}
+
+static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("240 60 15 3");
+static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO, 
+		mcp3422_show_scales, NULL, 0);
+
+static struct attribute *mcp3422_attributes[] = {
+	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
+	&iio_dev_attr_in_voltage_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(0),
+	MCP3422_CHAN(1),
+};
+
+static const struct iio_chan_spec mcp3424_channels[] = {
+	MCP3422_CHAN(0),
+	MCP3422_CHAN(1),
+	MCP3422_CHAN(2),
+	MCP3422_CHAN(3),
+};
+
+static const struct iio_info mcp3422_info = {
+	.read_raw = mcp3422_read_raw,
+	.write_raw = mcp3422_write_raw,
+	.write_raw_get_fmt = mcp3422_write_raw_get_fmt,
+	.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;
+
+	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;
+	}
+
+	/* 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);
+
+	err = iio_device_register(indio_dev);
+	if (err < 0)
+		return err;
+
+	i2c_set_clientdata(client, indio_dev);
+
+	return 0;
+}
+
+static int mcp3422_remove(struct i2c_client *client)
+{
+	iio_device_unregister(i2c_get_clientdata(client));
+	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@gmail.com>");
+MODULE_DESCRIPTION("Microchip mcp3422/3/4 driver");
+MODULE_LICENSE("GPL v2");
-- 
1.7.5.4

Re: [PATCH v10] Add Microchip MCP3422/3/4 high resolution ADC

[Jonathan Cameron]

On 09/02/13 15:00, Angelo Compagnucci wrote:
> Hi Jonathan,
> 
> Kawabonga! It works! Really, but really (no joke here!) thank you
> for your precious support and sorry for not being so smart to
> understand what you were saying me. Sorry again for being so pedantic!
> 
> I'm planning to write a tutorial based on my journey, something like
> "Howto write your first IIO LDD", what do you think?

An excellent thing to do.  There has been a fair bit of discussion about how to
get new hobbyist contributors to the kernel as part of the nomination process
for the kernel summit.  One of the things I suggested was that IIO was a good place
for people to get started (beyond the trivial cleanup or fix that gets a lot of people
their first patch).  I suggested that a tutorial such as you describe (perhaps
adding more bells and whistles (as later steps) that we keep up to date with api
changes etc would be an excellent resource.

The tutorial you are suggesting sounds like an excellent first step to such
a (perhaps?) more general resource if you are willing to have it used that way?

> 
> Attached here, there is the latest version of the patch based on jour suggestions.
> I think all of your concerns are solved now.
They are indeed.  Few new trivial bits that I have fixed up in the merge though.

1) Don't have this 'comment' stuff here in the email.  If you put it below the
--- then I don't end up editting it out. Much as I'd like to have kernel logs
with extensive TMHT references probably best not ;)

Also, bodging in my suggestions left some white space mess that I probably introduced
by writing some of those snippets of code in my email client.

Anyhow take a look at the tree and check I didn't mess anything up!
> 
> Thank you again!
> 
> Signed-off-by: Angelo Compagnucci <angelo.compagnucci@gmail.com>
Applied to the togreg branch of iio.git

> ---
>  drivers/iio/adc/Kconfig   |   10 +
>  drivers/iio/adc/Makefile  |    1 +
>  drivers/iio/adc/mcp3422.c |  409 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 420 insertions(+), 0 deletions(-)
>  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..4598a54
> --- /dev/null
> +++ b/drivers/iio/adc/mcp3422.c
> @@ -0,0 +1,409 @@
> +/*
> + * mcp3422.c - driver for the Microchip mcp3422/3/4 chip family
> + *
> + * Copyright (C) 2013, Angelo Compagnucci
> + * Author: Angelo Compagnucci <angelo.compagnucci@gmail.com>
> + *
> + * 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/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)
> +#define MCP3422_PGA(config)	((config) & MCP3422_PGA_MASK)
> +#define MCP3422_SAMPLE_RATE(config)	(((config) & MCP3422_SRATE_MASK) >> 2)
> +
> +#define MCP3422_CHANNEL_VALUE(value) (((value) << 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), \
> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SAMP_FREQ), \
> +	}
> +
> +/* LSB is in nV to eliminate floating point */
> +static const u32 rates_to_lsb[] = {1000000, 250000, 62500, 15625};
> +
> +/*
> + *  scales calculated as:
> + *  rates_to_lsb[sample_rate] / (1 << pga);
> + *  pga is 1 for 0, 2
> + */
> +
> +static const int mcp3422_scales[4][4] = {
> +	{ 1000000, 250000, 62500, 15625 },
> +	{ 500000 , 125000, 31250, 7812 },
> +	{ 250000 , 62500 , 15625, 3906 },
> +	{ 125000 , 31250 , 7812 , 1953 } };
> +
> +/* Constant msleep times for data acquisitions */
> +static const int mcp3422_read_times[4] = {
> +	[MCP3422_SRATE_240] = 1000 / 240,
> +	[MCP3422_SRATE_60] = 1000 / 60,
> +	[MCP3422_SRATE_15] = 1000 / 15,
> +	[MCP3422_SRATE_3] = 1000 / 3 };
> +
> +/* sample rates to integer conversion table */
> +static const int mcp3422_sample_rates[4] = {
> +	[MCP3422_SRATE_240] = 240,
> +	[MCP3422_SRATE_60] = 60,
> +	[MCP3422_SRATE_15] = 15,
> +	[MCP3422_SRATE_3] = 3 };
> +
> +/* sample rates to sign extension table */
> +static const int mcp3422_sign_extend[4] = {
> +	[MCP3422_SRATE_240] = 12,
> +	[MCP3422_SRATE_60] = 14,
> +	[MCP3422_SRATE_15] = 16,
> +	[MCP3422_SRATE_3] = 18 };
> +
> +/* 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;
> +		ret = 0;
> +	}
> +
> +	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];
> +	}
> +
> +	*value = sign_extend32(temp, mcp3422_sign_extend[sample_rate]);
> +
> +	return ret;
> +}
> +
> +static int mcp3422_read_channel(struct mcp3422 *adc,
> +				struct iio_chan_spec const *channel, int *value)
> +{
> +	int ret;
> +	u8 config;
> +	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]);
> +		ret = mcp3422_update_config(adc, config);
> +		if (ret < 0)
> +			return ret;
> +		msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(adc->config)]);
> +	}
> +
> +	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;
> +
> +	u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
> +	u8 pga		 = MCP3422_PGA(adc->config);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		err = mcp3422_read_channel(adc, channel, val1);
> +		if (err < 0)
> +			return -EINVAL;
> +		return IIO_VAL_INT;
> +
> +	case IIO_CHAN_INFO_SCALE:
> +
> +		*val1 = 0;
> +		*val2 = mcp3422_scales[sample_rate][pga];
> +		return IIO_VAL_INT_PLUS_NANO;
> +
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		*val1 = mcp3422_sample_rates[MCP3422_SAMPLE_RATE(adc->config)]; 
> +		return IIO_VAL_INT;
> +
> +	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 temp;
> +	u8 config = adc->config;
> +	u8 req_channel = channel->channel;
> +	u8 sample_rate = MCP3422_SAMPLE_RATE(config);
> +	u8 i;
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SCALE:
> +		if (val1 != 0)
> +			return -EINVAL;
> +
> +		for (i = 0; i < ARRAY_SIZE(mcp3422_scales[0]); i++) {
> +			if (val2 == mcp3422_scales[sample_rate][i]) {
> +				adc->pga[req_channel] = i;
> +				 
> +				config &= ~MCP3422_CHANNEL_MASK;
> +				config |= MCP3422_CHANNEL_VALUE(req_channel);
> +				config &= ~MCP3422_PGA_MASK;
> +				config |= MCP3422_PGA_VALUE(adc->pga[req_channel]);
> +
> +				return mcp3422_update_config(adc, config);
> +			} 
> +		}
> +		return -EINVAL;
> +
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		switch (val1) {
> +		case 240:
> +			temp = MCP3422_SRATE_240;
> +			break;
> +		case 60:
> +			temp = MCP3422_SRATE_60;
> +			break;
> +		case 15:
> +			temp = MCP3422_SRATE_15;
> +			break;
> +		case 3:
> +			temp = MCP3422_SRATE_3;
> +			break;
> +		default:
> +			return -EINVAL;
> +		}
> +
> +		config &= ~MCP3422_CHANNEL_MASK;
> +		config |= MCP3422_CHANNEL_VALUE(req_channel);
> +		config &= ~MCP3422_SRATE_MASK;
> +		config |= MCP3422_SAMPLE_RATE_VALUE(temp);
> +
> +		return mcp3422_update_config(adc, config);
> +
> +	default:
> +		break;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static int mcp3422_write_raw_get_fmt(struct iio_dev *indio_dev,
> +		struct iio_chan_spec const *chan, long mask)
> +{
> +	switch (mask) {
> +	case IIO_CHAN_INFO_SCALE:
> +		return IIO_VAL_INT_PLUS_NANO;
> +	case IIO_CHAN_INFO_SAMP_FREQ:
> +		return IIO_VAL_INT_PLUS_MICRO;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static ssize_t mcp3422_show_scales(struct device *dev, 
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct mcp3422 *adc = iio_priv(dev_to_iio_dev(dev));
> +	u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
> +
> +	return sprintf(buf, "0.%09u 0.%09u 0.%09u 0.%09u\n",
> +		mcp3422_scales[sample_rate][0],
> +		mcp3422_scales[sample_rate][1],
> +		mcp3422_scales[sample_rate][2],
> +		mcp3422_scales[sample_rate][3]);
> +}
> +
> +static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("240 60 15 3");
> +static IIO_DEVICE_ATTR(in_voltage_scale_available, S_IRUGO, 
> +		mcp3422_show_scales, NULL, 0);
> +
> +static struct attribute *mcp3422_attributes[] = {
> +	&iio_const_attr_sampling_frequency_available.dev_attr.attr,
> +	&iio_dev_attr_in_voltage_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(0),
> +	MCP3422_CHAN(1),
> +};
> +
> +static const struct iio_chan_spec mcp3424_channels[] = {
> +	MCP3422_CHAN(0),
> +	MCP3422_CHAN(1),
> +	MCP3422_CHAN(2),
> +	MCP3422_CHAN(3),
> +};
> +
> +static const struct iio_info mcp3422_info = {
> +	.read_raw = mcp3422_read_raw,
> +	.write_raw = mcp3422_write_raw,
> +	.write_raw_get_fmt = mcp3422_write_raw_get_fmt,
> +	.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;
> +
> +	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;
> +	}
> +
> +	/* 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);
> +
> +	err = iio_device_register(indio_dev);
> +	if (err < 0)
> +		return err;
> +
> +	i2c_set_clientdata(client, indio_dev);
> +
> +	return 0;
> +}
> +
> +static int mcp3422_remove(struct i2c_client *client)
> +{
> +	iio_device_unregister(i2c_get_clientdata(client));
> +	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@gmail.com>");
> +MODULE_DESCRIPTION("Microchip mcp3422/3/4 driver");
> +MODULE_LICENSE("GPL v2");
> 

Re: [PATCH v10] Add Microchip MCP3422/3/4 high resolution ADC

[Jonathan Cameron]

On 09/07/13 22:20, Jonathan Cameron wrote:
> On 09/02/13 15:00, Angelo Compagnucci wrote:
>> Hi Jonathan,
>>
>> Kawabonga! It works! Really, but really (no joke here!) thank you
>> for your precious support and sorry for not being so smart to
>> understand what you were saying me. Sorry again for being so pedantic!
>>
>> I'm planning to write a tutorial based on my journey, something like
>> "Howto write your first IIO LDD", what do you think?
> 
> An excellent thing to do.  There has been a fair bit of discussion about how to
> get new hobbyist contributors to the kernel as part of the nomination process
> for the kernel summit.  One of the things I suggested was that IIO was a good place
> for people to get started (beyond the trivial cleanup or fix that gets a lot of people
> their first patch).  I suggested that a tutorial such as you describe (perhaps
> adding more bells and whistles (as later steps) that we keep up to date with api
> changes etc would be an excellent resource.
> 
> The tutorial you are suggesting sounds like an excellent first step to such
> a (perhaps?) more general resource if you are willing to have it used that way?
> 
>>
>> Attached here, there is the latest version of the patch based on jour suggestions.
>> I think all of your concerns are solved now.
> They are indeed.  Few new trivial bits that I have fixed up in the merge though.
> 
> 1) Don't have this 'comment' stuff here in the email.  If you put it below the
> --- then I don't end up editting it out. Much as I'd like to have kernel logs
> with extensive TMHT references probably best not ;)
> 
> Also, bodging in my suggestions left some white space mess that I probably introduced
> by writing some of those snippets of code in my email client.
> 
I forgot to mention that every corner of the kernel has it's own unique patch title scheme
so you always need to take a look at other recent patches in the relevant area and copy the
form.  In the case of IIO I pinched it from somewhere else (can't remember where ;) and
went with
'iio: adc: New driver for... ' for the initial patch introducing the driver.
'iio: adc: mcp3422 ....' for follow up patches.

Few more points for the end of any tutorial!


> Anyhow take a look at the tree and check I didn't mess anything up!
>>
>> Thank you again!
>>
>> Signed-off-by: Angelo Compagnucci <angelo.compagnucci@gmail.com>
> Applied to the togreg branch of iio.git
> 

Re: [PATCH v10] Add Microchip MCP3422/3/4 high resolution ADC

[Otavio Salvador]

On Mon, Sep 2, 2013 at 11:00 AM, Angelo Compagnucci
<angelo.compagnucci@gmail.com> wrote:
> Kawabonga! It works! Really, but really (no joke here!) thank you
> for your precious support and sorry for not being so smart to
> understand what you were saying me. Sorry again for being so pedantic!
>
> I'm planning to write a tutorial based on my journey, something like
> "Howto write your first IIO LDD", what do you think?
>
> Attached here, there is the latest version of the patch based on jour suggestions.
> I think all of your concerns are solved now.
>
> Thank you again!
>
> Signed-off-by: Angelo Compagnucci <angelo.compagnucci@gmail.com>
...
> +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" },
> +       { }

Shouldn't this be mcp,mcp3422?

Another question, are you aware of need changes to use with mcp3428?
Otherwise I will look at this.

-- 
Otavio Salvador                             O.S. Systems
http://www.ossystems.com.br        http://code.ossystems.com.br
Mobile: +55 (53) 9981-7854            Mobile: +1 (347) 903-9750

Re: [PATCH v10] Add Microchip MCP3422/3/4 high resolution ADC

[Angelo Compagnucci]

Hi Otavio,

MCP3426/7/8 Are different beast, not so much different from
mcp3422/3/4. Actually I'm building a board to test out the code I'm
writing for MCP3426/7/8, and it should be ready in a few days.

After finalizing the code and the necessary QA, I will publish it on this ML.

Sincerly Angelo.


2013/11/20 Otavio Salvador <otavio@ossystems.com.br>:
> On Mon, Sep 2, 2013 at 11:00 AM, Angelo Compagnucci
> <angelo.compagnucci@gmail.com> wrote:
>> Kawabonga! It works! Really, but really (no joke here!) thank you
>> for your precious support and sorry for not being so smart to
>> understand what you were saying me. Sorry again for being so pedantic!
>>
>> I'm planning to write a tutorial based on my journey, something like
>> "Howto write your first IIO LDD", what do you think?
>>
>> Attached here, there is the latest version of the patch based on jour suggestions.
>> I think all of your concerns are solved now.
>>
>> Thank you again!
>>
>> Signed-off-by: Angelo Compagnucci <angelo.compagnucci@gmail.com>
> ...
>> +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" },
>> +       { }
>
> Shouldn't this be mcp,mcp3422?
>
> Another question, are you aware of need changes to use with mcp3428?
> Otherwise I will look at this.
>
> --
> Otavio Salvador                             O.S. Systems
> http://www.ossystems.com.br        http://code.ossystems.com.br
> Mobile: +55 (53) 9981-7854            Mobile: +1 (347) 903-9750



-- 
Profile: http://it.linkedin.com/in/compagnucciangelo

Re: [PATCH v10] Add Microchip MCP3422/3/4 high resolution ADC

[Otavio Salvador]

On Wed, Nov 20, 2013 at 8:24 AM, Angelo Compagnucci
<angelo.compagnucci@gmail.com> wrote:
> MCP3426/7/8 Are different beast, not so much different from
> mcp3422/3/4. Actually I'm building a board to test out the code I'm
> writing for MCP3426/7/8, and it should be ready in a few days.
>
> After finalizing the code and the necessary QA, I will publish it on this ML.

I have a board with it, so if you want I can give it a try.

-- 
Otavio Salvador                             O.S. Systems
http://www.ossystems.com.br        http://code.ossystems.com.br
Mobile: +55 (53) 9981-7854            Mobile: +1 (347) 903-9750