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kernel/drivers/iio/adc/mcp3911.c
Marcus Folkesson 3a89b289df iio: adc: add support for mcp3911 
MCP3911 is a dual channel Analog Front End (AFE) containing two
synchronous sampling delta-sigma Analog-to-Digital Converters (ADC).

Co-developed-by: Kent Gustavsson <kent@minoris.se>
Signed-off-by: Kent Gustavsson <kent@minoris.se>
Signed-off-by: Marcus Folkesson <marcus.folkesson@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
2018-08-19 20:02:48 +01:00

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// SPDX-License-Identifier: GPL-2.0
/*
* Driver for Microchip MCP3911, Two-channel Analog Front End
*
* Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@gmail.com>
* Copyright (C) 2018 Kent Gustavsson <kent@minoris.se>
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/iio/iio.h>
#include <linux/module.h>
#include <linux/regulator/consumer.h>
#include <linux/spi/spi.h>
#define MCP3911_REG_CHANNEL0 0x00
#define MCP3911_REG_CHANNEL1 0x03
#define MCP3911_REG_MOD 0x06
#define MCP3911_REG_PHASE 0x07
#define MCP3911_REG_GAIN 0x09
#define MCP3911_REG_STATUSCOM 0x0a
#define MCP3911_STATUSCOM_CH1_24WIDTH BIT(4)
#define MCP3911_STATUSCOM_CH0_24WIDTH BIT(3)
#define MCP3911_STATUSCOM_EN_OFFCAL BIT(2)
#define MCP3911_STATUSCOM_EN_GAINCAL BIT(1)
#define MCP3911_REG_CONFIG 0x0c
#define MCP3911_CONFIG_CLKEXT BIT(1)
#define MCP3911_CONFIG_VREFEXT BIT(2)
#define MCP3911_REG_OFFCAL_CH0 0x0e
#define MCP3911_REG_GAINCAL_CH0 0x11
#define MCP3911_REG_OFFCAL_CH1 0x14
#define MCP3911_REG_GAINCAL_CH1 0x17
#define MCP3911_REG_VREFCAL 0x1a
#define MCP3911_CHANNEL(x) (MCP3911_REG_CHANNEL0 + x * 3)
#define MCP3911_OFFCAL(x) (MCP3911_REG_OFFCAL_CH0 + x * 6)
/* Internal voltage reference in uV */
#define MCP3911_INT_VREF_UV 1200000
#define MCP3911_REG_READ(reg, id) ((((reg) << 1) | ((id) << 5) | (1 << 0)) & 0xff)
#define MCP3911_REG_WRITE(reg, id) ((((reg) << 1) | ((id) << 5) | (0 << 0)) & 0xff)
#define MCP3911_NUM_CHANNELS 2
struct mcp3911 {
struct spi_device *spi;
struct mutex lock;
struct regulator *vref;
struct clk *clki;
u32 dev_addr;
};
static int mcp3911_read(struct mcp3911 *adc, u8 reg, u32 *val, u8 len)
{
int ret;
reg = MCP3911_REG_READ(reg, adc->dev_addr);
ret = spi_write_then_read(adc->spi, &reg, 1, val, len);
if (ret < 0)
return ret;
be32_to_cpus(val);
*val >>= ((4 - len) * 8);
dev_dbg(&adc->spi->dev, "reading 0x%x from register 0x%x\n", *val,
reg >> 1);
return ret;
}
static int mcp3911_write(struct mcp3911 *adc, u8 reg, u32 val, u8 len)
{
dev_dbg(&adc->spi->dev, "writing 0x%x to register 0x%x\n", val, reg);
val <<= (3 - len) * 8;
cpu_to_be32s(&val);
val |= MCP3911_REG_WRITE(reg, adc->dev_addr);
return spi_write(adc->spi, &val, len + 1);
}
static int mcp3911_update(struct mcp3911 *adc, u8 reg, u32 mask,
u32 val, u8 len)
{
u32 tmp;
int ret;
ret = mcp3911_read(adc, reg, &tmp, len);
if (ret)
return ret;
val &= mask;
val |= tmp & ~mask;
return mcp3911_write(adc, reg, val, len);
}
static int mcp3911_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *channel, int *val,
int *val2, long mask)
{
struct mcp3911 *adc = iio_priv(indio_dev);
int ret = -EINVAL;
mutex_lock(&adc->lock);
switch (mask) {
case IIO_CHAN_INFO_RAW:
ret = mcp3911_read(adc,
MCP3911_CHANNEL(channel->channel), val, 3);
if (ret)
goto out;
ret = IIO_VAL_INT;
break;
case IIO_CHAN_INFO_OFFSET:
ret = mcp3911_read(adc,
MCP3911_OFFCAL(channel->channel), val, 3);
if (ret)
goto out;
ret = IIO_VAL_INT;
break;
case IIO_CHAN_INFO_SCALE:
if (adc->vref) {
ret = regulator_get_voltage(adc->vref);
if (ret < 0) {
dev_err(indio_dev->dev.parent,
"failed to get vref voltage: %d\n",
ret);
goto out;
}
*val = ret / 1000;
} else {
*val = MCP3911_INT_VREF_UV;
}
*val2 = 24;
ret = IIO_VAL_FRACTIONAL_LOG2;
break;
}
out:
mutex_unlock(&adc->lock);
return ret;
}
static int mcp3911_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *channel, int val,
int val2, long mask)
{
struct mcp3911 *adc = iio_priv(indio_dev);
int ret = -EINVAL;
mutex_lock(&adc->lock);
switch (mask) {
case IIO_CHAN_INFO_OFFSET:
if (val2 != 0) {
ret = -EINVAL;
goto out;
}
/* Write offset */
ret = mcp3911_write(adc, MCP3911_OFFCAL(channel->channel), val,
3);
if (ret)
goto out;
/* Enable offset*/
ret = mcp3911_update(adc, MCP3911_REG_STATUSCOM,
MCP3911_STATUSCOM_EN_OFFCAL,
MCP3911_STATUSCOM_EN_OFFCAL, 2);
break;
}
out:
mutex_unlock(&adc->lock);
return ret;
}
#define MCP3911_CHAN(idx) { \
.type = IIO_VOLTAGE, \
.indexed = 1, \
.channel = idx, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | \
BIT(IIO_CHAN_INFO_OFFSET) | \
BIT(IIO_CHAN_INFO_SCALE), \
}
static const struct iio_chan_spec mcp3911_channels[] = {
MCP3911_CHAN(0),
MCP3911_CHAN(1),
};
static const struct iio_info mcp3911_info = {
.read_raw = mcp3911_read_raw,
.write_raw = mcp3911_write_raw,
};
static int mcp3911_config(struct mcp3911 *adc, struct device_node *of_node)
{
u32 configreg;
int ret;
of_property_read_u32(of_node, "device-addr", &adc->dev_addr);
if (adc->dev_addr > 3) {
dev_err(&adc->spi->dev,
"invalid device address (%i). Must be in range 0-3.\n",
adc->dev_addr);
return -EINVAL;
}
dev_dbg(&adc->spi->dev, "use device address %i\n", adc->dev_addr);
ret = mcp3911_read(adc, MCP3911_REG_CONFIG, &configreg, 2);
if (ret)
return ret;
if (adc->vref) {
dev_dbg(&adc->spi->dev, "use external voltage reference\n");
configreg |= MCP3911_CONFIG_VREFEXT;
} else {
dev_dbg(&adc->spi->dev,
"use internal voltage reference (1.2V)\n");
configreg &= ~MCP3911_CONFIG_VREFEXT;
}
if (adc->clki) {
dev_dbg(&adc->spi->dev, "use external clock as clocksource\n");
configreg |= MCP3911_CONFIG_CLKEXT;
} else {
dev_dbg(&adc->spi->dev,
"use crystal oscillator as clocksource\n");
configreg &= ~MCP3911_CONFIG_CLKEXT;
}
return mcp3911_write(adc, MCP3911_REG_CONFIG, configreg, 2);
}
static int mcp3911_probe(struct spi_device *spi)
{
struct iio_dev *indio_dev;
struct mcp3911 *adc;
int ret;
indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*adc));
if (!indio_dev)
return -ENOMEM;
adc = iio_priv(indio_dev);
adc->spi = spi;
adc->vref = devm_regulator_get_optional(&adc->spi->dev, "vref");
if (IS_ERR(adc->vref)) {
if (PTR_ERR(adc->vref) == -ENODEV) {
adc->vref = NULL;
} else {
dev_err(&adc->spi->dev,
"failed to get regulator (%ld)\n",
PTR_ERR(adc->vref));
return PTR_ERR(adc->vref);
}
} else {
ret = regulator_enable(adc->vref);
if (ret)
return ret;
}
adc->clki = devm_clk_get(&adc->spi->dev, NULL);
if (IS_ERR(adc->clki)) {
if (PTR_ERR(adc->clki) == -ENOENT) {
adc->clki = NULL;
} else {
dev_err(&adc->spi->dev,
"failed to get adc clk (%ld)\n",
PTR_ERR(adc->clki));
ret = PTR_ERR(adc->clki);
goto reg_disable;
}
} else {
ret = clk_prepare_enable(adc->clki);
if (ret < 0) {
dev_err(&adc->spi->dev,
"Failed to enable clki: %d\n", ret);
goto reg_disable;
}
}
ret = mcp3911_config(adc, spi->dev.of_node);
if (ret)
goto clk_disable;
indio_dev->dev.parent = &spi->dev;
indio_dev->dev.of_node = spi->dev.of_node;
indio_dev->name = spi_get_device_id(spi)->name;
indio_dev->modes = INDIO_DIRECT_MODE;
indio_dev->info = &mcp3911_info;
spi_set_drvdata(spi, indio_dev);
indio_dev->channels = mcp3911_channels;
indio_dev->num_channels = ARRAY_SIZE(mcp3911_channels);
mutex_init(&adc->lock);
ret = iio_device_register(indio_dev);
if (ret)
goto clk_disable;
return ret;
clk_disable:
clk_disable_unprepare(adc->clki);
reg_disable:
if (adc->vref)
regulator_disable(adc->vref);
return ret;
}
static int mcp3911_remove(struct spi_device *spi)
{
struct iio_dev *indio_dev = spi_get_drvdata(spi);
struct mcp3911 *adc = iio_priv(indio_dev);
iio_device_unregister(indio_dev);
clk_disable_unprepare(adc->clki);
if (adc->vref)
regulator_disable(adc->vref);
return 0;
}
static const struct of_device_id mcp3911_dt_ids[] = {
{ .compatible = "microchip,mcp3911" },
{ }
};
MODULE_DEVICE_TABLE(of, mcp3911_dt_ids);
static const struct spi_device_id mcp3911_id[] = {
{ "mcp3911", 0 },
{ }
};
MODULE_DEVICE_TABLE(spi, mcp3911_id);
static struct spi_driver mcp3911_driver = {
.driver = {
.name = "mcp3911",
.of_match_table = mcp3911_dt_ids,
},
.probe = mcp3911_probe,
.remove = mcp3911_remove,
.id_table = mcp3911_id,
};
module_spi_driver(mcp3911_driver);
MODULE_AUTHOR("Marcus Folkesson <marcus.folkesson@gmail.com>");
MODULE_AUTHOR("Kent Gustavsson <kent@minoris.se>");
MODULE_DESCRIPTION("Microchip Technology MCP3911");
MODULE_LICENSE("GPL v2");
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