Add Microchip MCP3422/3/4 high resolution ADC
PATCH v9 1/1 Add Microchip MCP3422/3/4 high resolution ADC
I think this patch solves last Jonathan's concerns.
Following a use case from a running chip, just to be sure the driver works like it should:
# cat in_voltage0_* 2047 0.001000000 //this is the scale # echo 3 > in_voltage_sampling_frequency # cat in_voltage0_* 131071 0.000015625 //this is the scale # echo 8 > in_voltage0_scale # cat in_voltage0_* 25 //small voltage value to see the pga in action 0.000001953 //this is the scale
So in the first case, 2047 * 0.001 = 2.047, in the second one 131071 * 0.000015625 = 2.047984375, in the third one 25 * 0.000001953 = 0.000048825, on all three cases I have the expected values.
Is ths correct?
Thank you!
Signed-off-by Angelo Compagnucci <[email protected]>
--- drivers/iio/adc/Kconfig | 10 + drivers/iio/adc/Makefile | 1 + drivers/iio/adc/mcp3422.c | 400 +++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 411 insertions(+), 0 deletions(-) create mode 100644 drivers/iio/adc/mcp3422.c
drivers/iio/adc/Kconfig +10 -0
@@ -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
drivers/iio/adc/Makefile +1 -0
@@ -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
drivers/iio/adc/mcp3422.c new file +400 -0
400 lines not on this page · raw message
Signature · 1 line
1.7.5.4
Jonathan Cameron
maintainerQuoted 2 lines · Angelo Compagnucci
I think this patch solves last Jonathan's concerns.
All but one I think... See below. Also as a brief note, you are are well beyond an RFC now (which is typically used to tag code that the author isn't proposing should be applied, but rather is just a 'request for comment!). Hence drop that tag.
Quoted 11 lines
Following a use case from a running chip, just to be sure the driver works like it should:
# cat in_voltage0_* 2047 0.001000000 //this is the scale # echo 3 > in_voltage_sampling_frequency # cat in_voltage0_* 131071 0.000015625 //this is the scale # echo 8 > in_voltage0_scale
Sorry this is not quite correct. What you write to in_voltage0_scale should be the same as what is read from it. Hence what you want is:
# echo 0.000001953 > in_voltage0_scale # cat in_voltage0_* 25 0.000001953
I've explained roughly how I'd implement this inline. Note of course that my code is badly formatted and probably filled with bugs, but I hope it shows clearly what I mean.
Sorry I wasn't clearer on this. An equivalent of your example would have made this obvious but I didn't provide one!
Give me a shout if anything is unclear.
Jonathan
# cat in_voltage0_*
Quoted 187 lines
25 //small voltage value to see the pga in action
0.000001953 //this is the scaleSo in the first case, 2047 * 0.001 = 2.047, in the second one 131071 * 0.000015625 = 2.047984375, in the third one 25 * 0.000001953 = 0.000048825, on all three cases I have the expected values.
Is ths correct?
Thank you!
Signed-off-by Angelo Compagnucci <[email protected]>--- drivers/iio/adc/Kconfig | 10 + drivers/iio/adc/Makefile | 1 + drivers/iio/adc/mcp3422.c | 400 +++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 411 insertions(+), 0 deletions(-) create mode 100644 drivers/iio/adc/mcp3422.cdrivers/iio/adc/Kconfig +10
-0@@ -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 I2Cdrivers/iio/adc/Makefile +1
-0@@ -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.odrivers/iio/adc/mcp3422.c new file +128
-0@@ -0,0 +1,400 @@ +/* +* mcp3422.c - driver for the Microchip mcp3422/3/4 chip family +* +* Copyright (C) 2013, Angelo Compagnucci +* Author: Angelo Compagnucci <[email protected]> +* +* 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 }; + +/* 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 ]; + } + +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, ret; +u8 config =0 ; +u8 req_channel = channel->channel; +
drivers/iio/adc/mcp3422.c line 138
Quoted 10 lines
drivers/iio/adc/mcp3422.c new file +10
-0+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; +switch (MCP3422_SAMPLE_RATE (config)) {
Just a passing thought. I'd do this as a look up table just above this function:
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 };Then here you simply have
msleep(mcp3422_read_times[MCP3422_SAMPLE_RATE(config)]);
This 'trick' could also be used to shorten a few other functions. Far from critical though if you would rather not!
Quoted 9 lines
drivers/iio/adc/mcp3422.c new file +9
-0+case MCP3422_SRATE_240 : + mtime =1000 /240 ; +break ; +case MCP3422_SRATE_60 : + mtime =1000 /60 ; +break ; +case MCP3422_SRATE_15 : + mtime =1000 /15 ; +break ;
drivers/iio/adc/mcp3422.c line 157
Quoted 10 lines
drivers/iio/adc/mcp3422.c new file +10
-0+case MCP3422_SRATE_3 : + mtime =1000 /3 ; +break ; + } +msleep (mtime); + } + +return mcp3422_read (adc, value, &config); +} +
/*
* scales calculated as:
* rates_to_lsb[sample_rate] / (1 << pga);
* pga is 1 for 0, 2
*/
static const mcp3422_scales[4][4] = {
{ 0001000000, 0000250000, 000062500, 00000015625 },
{ 0000500000, 0000125000, 000031250, 00000007812 },
{ 0000250000, 0000062500, 000015625, 00000003906 },
{ 0000125000, 0000031250, 000007812, 00000001953 } };Quoted 51 lines
drivers/iio/adc/mcp3422.c new file +50
-0+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 = rates_to_lsb[sample_rate] / (pga ?1 << pga :1 ); + + *val1 =0 ; + *val2 = mcp3422_scales[sample_rate][pga]; +return IIO_VAL_INT_PLUS_NANO ; + +case IIO_CHAN_INFO_SAMP_FREQ : +switch (MCP3422_SAMPLE_RATE (adc->config)) { +case MCP3422_SRATE_240 : + *val1 =240 ; +break ; +case MCP3422_SRATE_60 : + *val1 =60 ; +break ; +case MCP3422_SRATE_15 : + *val1 =15 ; +break ; +case MCP3422_SRATE_3 : + *val1 =3 ; +break ; + } +return IIO_VAL_INT ; + +default : +break ; + } + +return -EINVAL ;
drivers/iio/adc/mcp3422.c line 217
Quoted 10 lines
drivers/iio/adc/mcp3422.c new file +10
-0+} + +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;
int i; u8 sample_rate = MCP3422_SAMPLE_RATE(adc->config);
drivers/iio/adc/mcp3422.c line 178
Quoted 3 lines
drivers/iio/adc/mcp3422.c new file +3
-0+ +switch (mask) { +case IIO_CHAN_INFO_SCALE :
if (val1 != 0)
return -EINVAL; /* Pass only the row of the table that corresponds to current sampling freq */ for (i = 0; i < ARRAY_SIZE(mcp3422_scales[0]); i++) if (val2 == mcp3422_scales[samplerate][i]) break;
//Now obligingly the value i is I believe what you want to put in here already, // if not a small conversion static const array is in order...
adc->pga[req_channel] = i;
/* snip
Quoted 9 lines
drivers/iio/adc/mcp3422.c new file +9
-0+switch (val1) { +case 1 : + temp =MCP3422_PGA_1 ; +break ; +case 2 : + temp =MCP3422_PGA_2 ; +break ; +case 4 : + temp =MCP3422_PGA_4 ;
drivers/iio/adc/mcp3422.c line 239
Quoted 10 lines
drivers/iio/adc/mcp3422.c new file +10
-0+break ; +case 8 : + temp =MCP3422_PGA_8 ; +break ; +default : +return -EINVAL ; + } + + adc->pga[req_channel] = temp; +
*/
Quoted 28 lines
drivers/iio/adc/mcp3422.c new file +28
-0+ 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); + +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 ;
drivers/iio/adc/mcp3422.c line 277
Quoted 10 lines
drivers/iio/adc/mcp3422.c new file +10
-0+ config |=MCP3422_SAMPLE_RATE_VALUE (temp); + +return mcp3422_update_config (adc, config); + +default : +break ; + } + +return -EINVAL ; +}
One other gotcha here unfortunately. Write_raw is assumed to take an int + micro but you have int + nano so we'll need the get format callback. Pinching the code from ad7793 and addint the two cases:
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;
}
}drivers/iio/adc/mcp3422.c line 281
Quoted 4 lines
drivers/iio/adc/mcp3422.c new file +4
-0+ +static IIO_CONST_ATTR_SAMP_FREQ_AVAIL("240 60 15 3"); +static IIO_CONST_ATTR(in_voltage_scale_available, "1 2 4 8"); +
Unfortunately you can't do this as the available scales are dependent on the sampling frequency. Hence you'll need a little function to do it for you. I'll probably get something wrong but along the lines of:
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",
mcp4322_scales[sample_rate][0],
mcp4322_scales[sample_rate][1],
mcp4322_scales[sample_rate][2],
mcp4322_scales[sample_rate][3]);}
static IIO_DEV_ATTR(in_voltage_scale_available, S_IRUGO,
mcp3422_show_scales, NULL);
Quoted 15 lines
drivers/iio/adc/mcp3422.c new file +15
-0+static struct attribute *mcp3422_attributes[] = { + &iio_const_attr_sampling_frequency_available.dev_attr.attr, + &iio_const_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 ), +}; +
drivers/iio/adc/mcp3422.c line 306
Quoted 10 lines
drivers/iio/adc/mcp3422.c new file +10
-0+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 = &mcp4322_write_raw_get_fmt,
Quoted 95 lines
drivers/iio/adc/mcp3422.c new file +94
-0+ .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 <[email protected]>" ); +MODULE_DESCRIPTION ("Microchip mcp3422/3/4 driver" ); +MODULE_LICENSE ("GPL v2" );