iio: adc: Add Maxim MAX11100 driver

Add iio driver for Maxim MAX11100 single-channel ADC.

Signed-off-by: Jacopo Mondi <jacopo+renesas@jmondi.org>
Tested-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 817693a14eb9eee2cc31e65f2caccf1037f83312..a8155221f47029484ec9293dbc0b674e92349293 100644 (file)
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -326,6 +326,15 @@ config MAX1027
          To compile this driver as a module, choose M here: the module will be
          called max1027.
 
+config MAX11100
+       tristate "Maxim max11100 ADC driver"
+       depends on SPI_MASTER
+       help
+         Say yes here to build support for Maxim max11100 SPI ADC
+
+         To compile this driver as a module, choose M here: the module will be
+         called max11100.
+
 config MAX1363
        tristate "Maxim max1363 ADC driver"
        depends on I2C

diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 260d083a2b3fb7c7853ca55700c79e5bd07b80b8..a90cdea61d0263b4324de4e115308715124eac9c 100644 (file)
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -32,6 +32,7 @@ obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
 obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o
 obj-$(CONFIG_LTC2485) += ltc2485.o
 obj-$(CONFIG_MAX1027) += max1027.o
+obj-$(CONFIG_MAX11100) += max11100.o
 obj-$(CONFIG_MAX1363) += max1363.o
 obj-$(CONFIG_MCP320X) += mcp320x.o
 obj-$(CONFIG_MCP3422) += mcp3422.o

diff --git a/drivers/iio/adc/max11100.c b/drivers/iio/adc/max11100.c
new file mode 100644 (file)
index 0000000..b738ecf
--- /dev/null
+++ b/drivers/iio/adc/max11100.c
@@ -0,0 +1,192 @@
+/*
+ * iio/adc/max11100.c
+ * Maxim max11100 ADC Driver with IIO interface
+ *
+ * Copyright (C) 2016-17 Renesas Electronics Corporation
+ * Copyright (C) 2016-17 Jacopo Mondi
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/delay.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#include <linux/iio/iio.h>
+#include <linux/iio/driver.h>
+
+/*
+ * LSB is the ADC single digital step
+ * 1 LSB = (vref_mv / 2 ^ 16)
+ *
+ * LSB is used to calculate analog voltage value
+ * from the number of ADC steps count
+ *
+ * Ain = (count * LSB)
+ */
+#define MAX11100_LSB_DIV               (1 << 16)
+
+struct max11100_state {
+       const struct max11100_chip_desc *desc;
+       struct regulator *vref_reg;
+       struct spi_device *spi;
+
+       /*
+        * DMA (thus cache coherency maintenance) requires the
+        * transfer buffers to live in their own cache lines.
+        */
+       u8 buffer[3] ____cacheline_aligned;
+};
+
+static struct iio_chan_spec max11100_channels[] = {
+       { /* [0] */
+               .type = IIO_VOLTAGE,
+               .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
+                                     BIT(IIO_CHAN_INFO_SCALE),
+       },
+};
+
+static struct max11100_chip_desc {
+       unsigned int num_chan;
+       const struct iio_chan_spec *channels;
+} max11100_desc = {
+       .num_chan = ARRAY_SIZE(max11100_channels),
+       .channels = max11100_channels,
+};
+
+static int max11100_read_single(struct iio_dev *indio_dev, int *val)
+{
+       int ret;
+       struct max11100_state *state = iio_priv(indio_dev);
+
+       ret = spi_read(state->spi, state->buffer, sizeof(state->buffer));
+       if (ret) {
+               dev_err(&indio_dev->dev, "SPI transfer failed\n");
+               return ret;
+       }
+
+       /* the first 8 bits sent out from ADC must be 0s */
+       if (state->buffer[0]) {
+               dev_err(&indio_dev->dev, "Invalid value: buffer[0] != 0\n");
+               return -EINVAL;
+       }
+
+       *val = (state->buffer[1] << 8) | state->buffer[2];
+
+       return 0;
+}
+
+static int max11100_read_raw(struct iio_dev *indio_dev,
+                            struct iio_chan_spec const *chan,
+                            int *val, int *val2, long info)
+{
+       int ret, vref_uv;
+       struct max11100_state *state = iio_priv(indio_dev);
+
+       switch (info) {
+       case IIO_CHAN_INFO_RAW:
+               ret = max11100_read_single(indio_dev, val);
+               if (ret)
+                       return ret;
+
+               return IIO_VAL_INT;
+
+       case IIO_CHAN_INFO_SCALE:
+               vref_uv = regulator_get_voltage(state->vref_reg);
+               if (vref_uv < 0)
+                       /* dummy regulator "get_voltage" returns -EINVAL */
+                       return -EINVAL;
+
+               *val =  vref_uv / 1000;
+               *val2 = MAX11100_LSB_DIV;
+               return IIO_VAL_FRACTIONAL;
+       }
+
+       return -EINVAL;
+}
+
+static const struct iio_info max11100_info = {
+       .driver_module = THIS_MODULE,
+       .read_raw = max11100_read_raw,
+};
+
+static int max11100_probe(struct spi_device *spi)
+{
+       int ret;
+       struct iio_dev *indio_dev;
+       struct max11100_state *state;
+
+       indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
+       if (!indio_dev)
+               return -ENOMEM;
+
+       spi_set_drvdata(spi, indio_dev);
+
+       state = iio_priv(indio_dev);
+       state->spi = spi;
+       state->desc = &max11100_desc;
+
+       indio_dev->dev.parent = &spi->dev;
+       indio_dev->dev.of_node = spi->dev.of_node;
+       indio_dev->name = "max11100";
+       indio_dev->info = &max11100_info;
+       indio_dev->modes = INDIO_DIRECT_MODE;
+       indio_dev->channels = state->desc->channels;
+       indio_dev->num_channels = state->desc->num_chan;
+
+       state->vref_reg = devm_regulator_get(&spi->dev, "vref");
+       if (IS_ERR(state->vref_reg))
+               return PTR_ERR(state->vref_reg);
+
+       ret = regulator_enable(state->vref_reg);
+       if (ret)
+               return ret;
+
+       ret = iio_device_register(indio_dev);
+       if (ret)
+               goto disable_regulator;
+
+       return 0;
+
+disable_regulator:
+       regulator_disable(state->vref_reg);
+
+       return ret;
+}
+
+static int max11100_remove(struct spi_device *spi)
+{
+       struct iio_dev *indio_dev = spi_get_drvdata(spi);
+       struct max11100_state *state = iio_priv(indio_dev);
+
+       regulator_disable(state->vref_reg);
+
+       iio_device_unregister(indio_dev);
+
+       return 0;
+}
+
+static const struct of_device_id max11100_ids[] = {
+       {.compatible = "maxim,max11100"},
+       { },
+};
+MODULE_DEVICE_TABLE(of, max11100_ids);
+
+static struct spi_driver max11100_driver = {
+       .driver = {
+               .name   = "max11100",
+               .owner  = THIS_MODULE,
+               .of_match_table = of_match_ptr(max11100_ids),
+       },
+       .probe          = max11100_probe,
+       .remove         = max11100_remove,
+};
+
+module_spi_driver(max11100_driver);
+
+MODULE_AUTHOR("Jacopo Mondi <jacopo@jmondi.org>");
+MODULE_DESCRIPTION("Maxim max11100 ADC Driver");
+MODULE_LICENSE("GPL v2");