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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, ®, 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->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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