diff options
Diffstat (limited to 'drivers/iio/adc/mcp3911.c')
| -rw-r--r-- | drivers/iio/adc/mcp3911.c | 363 |
1 files changed, 363 insertions, 0 deletions
diff --git a/drivers/iio/adc/mcp3911.c b/drivers/iio/adc/mcp3911.c new file mode 100644 index 000000000000..dd52f08ec82e --- /dev/null +++ b/drivers/iio/adc/mcp3911.c @@ -0,0 +1,363 @@ +// 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, ®, 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"); |