Re: [PATCH v5] iio: dac: mcp4902/mcp4912/mcp4922 dac driver
From: Jonathan Cameron
Date: Sat Jun 21 2014 - 06:51:18 EST
On 15/06/14 22:17, Michael Welling wrote:
This patch provides an iio device driver for the Microchip
MCP49x2 series DACs.
Normally this lot goes below the --- inorder that it doesn't then lead
to really long commit messages in git. Anyhow, I just dropped this stuff
during the commit. It's enough to have it in the list archives.
v5:
- Removes wildcard naming in filename and variables.
- Switches to using iio_device_register/unregister to avoid race condition.
- Removes --- around help in the Kconfig entry.
- Removes unused variable.
- Adds checking for val2 in write_raw function.
v4:
- Removes use of old IIO_ST macro.
- Moves mosi variable to the state struct.
- Removes default vref of 2.5v.
v3:
- Removes MCP49X2_RES_MASK and uses GENMASK directly.
- Switch from using address to channel in functions.
v2:
- Switched to using GENMASK instead of creating a mask directly.
- Switched from using address to channel.
- Removed unnecessary feilds from channel macro.
- Made SPI buffer cachline aligned.
- Removed some uncessary bounds checking.
- Report -EINVAL when writing a value beyond the range to DAC.
- Switched to devm_iio_device_alloc.
- Created a constant for the number of channels.
- Switched to devm_ioo_device_register.
Signed-off-by: Michael Welling <mwelling@xxxxxxxx>
Applied to the togreg branch of iio.git. Note this is initially pushed
out as testing to allow the autobuilders to do there work before I commit
to not rebasing the tree!
Thanks for your hard work on this. It's a nice little driver!
Jonathan
---
drivers/iio/dac/Kconfig | 10 +++
drivers/iio/dac/Makefile | 1 +
drivers/iio/dac/mcp4922.c | 216 +++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 227 insertions(+)
create mode 100644 drivers/iio/dac/mcp4922.c
diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index f378ca8..f278eff 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -163,4 +163,14 @@ config MCP4725
To compile this driver as a module, choose M here: the module
will be called mcp4725.
+config MCP4922
+ tristate "MCP4902, MCP4912, MCP4922 DAC driver"
+ depends on SPI
+ help
+ Say yes here to build the driver for the Microchip MCP4902
+ MCP4912, and MCP4922 DAC devices.
+
+ To compile this driver as a module, choose M here: the module
+ will be called mcp4922.
+
endmenu
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index bb84ad6..1010764 100644
--- a/drivers/iio/dac/Makefile
+++ b/drivers/iio/dac/Makefile
@@ -18,3 +18,4 @@ obj-$(CONFIG_AD5686) += ad5686.o
obj-$(CONFIG_AD7303) += ad7303.o
obj-$(CONFIG_MAX517) += max517.o
obj-$(CONFIG_MCP4725) += mcp4725.o
+obj-$(CONFIG_MCP4922) += mcp4922.o
diff --git a/drivers/iio/dac/mcp4922.c b/drivers/iio/dac/mcp4922.c
new file mode 100644
index 0000000..92cf4ca
--- /dev/null
+++ b/drivers/iio/dac/mcp4922.c
@@ -0,0 +1,216 @@
+/*
+ * mcp4922.c
+ *
+ * Driver for Microchip Digital to Analog Converters.
+ * Supports MCP4902, MCP4912, and MCP4922.
+ *
+ * Copyright (c) 2014 EMAC Inc.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/spi/spi.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/regulator/consumer.h>
+#include <linux/bitops.h>
+
+#define MCP4922_NUM_CHANNELS 2
+
+enum mcp4922_supported_device_ids {
+ ID_MCP4902,
+ ID_MCP4912,
+ ID_MCP4922,
+};
+
+struct mcp4922_state {
+ struct spi_device *spi;
+ unsigned int value[MCP4922_NUM_CHANNELS];
+ unsigned int vref_mv;
+ struct regulator *vref_reg;
+ u8 mosi[2] ____cacheline_aligned;
+};
+
+#define MCP4922_CHAN(chan, bits) { \
+ .type = IIO_VOLTAGE, \
+ .output = 1, \
+ .indexed = 1, \
+ .channel = chan, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+ .scan_type = { \
+ .sign = 'u', \
+ .realbits = (bits), \
+ .storagebits = 16, \
+ .shift = 12 - (bits), \
+ }, \
+}
+
+static int mcp4922_spi_write(struct mcp4922_state *state, u8 addr, u32 val)
+{
+ state->mosi[1] = val & 0xff;
+ state->mosi[0] = (addr == 0) ? 0x00 : 0x80;
+ state->mosi[0] |= 0x30 | ((val >> 8) & 0x0f);
+
+ return spi_write(state->spi, state->mosi, 2);
+}
+
+static int mcp4922_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val,
+ int *val2,
+ long mask)
+{
+ struct mcp4922_state *state = iio_priv(indio_dev);
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ *val = state->value[chan->channel];
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_SCALE:
+ *val = state->vref_mv;
+ *val2 = chan->scan_type.realbits;
+ return IIO_VAL_FRACTIONAL_LOG2;
+ default:
+ return -EINVAL;
+ }
+}
+
+static int mcp4922_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int val,
+ int val2,
+ long mask)
+{
+ struct mcp4922_state *state = iio_priv(indio_dev);
+
+ if (val2 != 0)
+ return -EINVAL;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ if (val > GENMASK(chan->scan_type.realbits-1, 0))
+ return -EINVAL;
+ val <<= chan->scan_type.shift;
+ state->value[chan->channel] = val;
+ return mcp4922_spi_write(state, chan->channel, val);
+ default:
+ return -EINVAL;
+ }
+}
+
+static const struct iio_chan_spec mcp4922_channels[3][MCP4922_NUM_CHANNELS] = {
+ [ID_MCP4902] = { MCP4922_CHAN(0, 8), MCP4922_CHAN(1, 8) },
+ [ID_MCP4912] = { MCP4922_CHAN(0, 10), MCP4922_CHAN(1, 10) },
+ [ID_MCP4922] = { MCP4922_CHAN(0, 12), MCP4922_CHAN(1, 12) },
+};
+
+static const struct iio_info mcp4922_info = {
+ .read_raw = &mcp4922_read_raw,
+ .write_raw = &mcp4922_write_raw,
+ .driver_module = THIS_MODULE,
+};
+
+static int mcp4922_probe(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev;
+ struct mcp4922_state *state;
+ const struct spi_device_id *id;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state));
+ if (indio_dev == NULL)
+ return -ENOMEM;
+
+ state = iio_priv(indio_dev);
+ state->spi = spi;
+ state->vref_reg = devm_regulator_get(&spi->dev, "vref");
+ if (IS_ERR(state->vref_reg)) {
+ dev_err(&spi->dev, "Vref regulator not specified\n");
+ return PTR_ERR(state->vref_reg);
+ }
+
+ ret = regulator_enable(state->vref_reg);
+ if (ret) {
+ dev_err(&spi->dev, "Failed to enable vref regulator: %d\n",
+ ret);
+ return ret;
+ }
+
+ ret = regulator_get_voltage(state->vref_reg);
+ if (ret < 0) {
+ dev_err(&spi->dev, "Failed to read vref regulator: %d\n",
+ ret);
+ goto error_disable_reg;
+ }
+ state->vref_mv = ret / 1000;
+
+ spi_set_drvdata(spi, indio_dev);
+ id = spi_get_device_id(spi);
+ indio_dev->dev.parent = &spi->dev;
+ indio_dev->info = &mcp4922_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->channels = mcp4922_channels[id->driver_data];
+ indio_dev->num_channels = MCP4922_NUM_CHANNELS;
+ indio_dev->name = id->name;
+
+ ret = iio_device_register(indio_dev);
+ if (ret) {
+ dev_err(&spi->dev, "Failed to register iio device: %d\n",
+ ret);
+ goto error_disable_reg;
+ }
+
+ return 0;
+
+error_disable_reg:
+ regulator_disable(state->vref_reg);
+
+ return ret;
+}
+
+static int mcp4922_remove(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev = spi_get_drvdata(spi);
+ struct mcp4922_state *state;
+
+ iio_device_unregister(indio_dev);
+ state = iio_priv(indio_dev);
+ regulator_disable(state->vref_reg);
+
+ return 0;
+}
+
+static const struct spi_device_id mcp4922_id[] = {
+ {"mcp4902", ID_MCP4902},
+ {"mcp4912", ID_MCP4912},
+ {"mcp4922", ID_MCP4922},
+ {}
+};
+MODULE_DEVICE_TABLE(spi, mcp4922_id);
+
+static struct spi_driver mcp4922_driver = {
+ .driver = {
+ .name = "mcp4922",
+ .owner = THIS_MODULE,
+ },
+ .probe = mcp4922_probe,
+ .remove = mcp4922_remove,
+ .id_table = mcp4922_id,
+};
+module_spi_driver(mcp4922_driver);
+
+MODULE_AUTHOR("Michael Welling <mwelling@xxxxxxxx>");
+MODULE_DESCRIPTION("Microchip MCP4902, MCP4912, MCP4922 DAC");
+MODULE_LICENSE("GPL v2");
--
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