The TI DAC8554 is a quad-channel Digital-to-Analog Converter with an SPI
interface.
Changes in v2:
* Use DMA-safe buffer for SPI transfer
* Normalize powerdown_mode name "hi-z" to "three_state" as per
ABI/testing/sysfs-bus-iio
* Register device late in probe function
* Avoid powerdown broadcast update, which touches all DAC on the bus
Signed-off-by: Nikolaus Schulz <nikolaus.sch...@avionic-design.de>
---
drivers/iio/dac/Kconfig | 10 ++
drivers/iio/dac/Makefile | 1 +
drivers/iio/dac/ti-dac8554.c | 374 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 385 insertions(+)
create mode 100644 drivers/iio/dac/ti-dac8554.c
diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index 2236ea2..1689260 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -181,4 +181,14 @@ config MCP4922
To compile this driver as a module, choose M here: the module
will be called mcp4922.
+config TI_DAC8554
+ tristate "TI DAC8554 driver"
+ depends on SPI
+ depends on OF
+ help
+ Say yes here to build the driver for the TI DAC8554.
+
+ To compile this driver as a module, choose M here: the module
+ will be called ti-dac8554.
+
endmenu
diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index 52be7e1..b98d79a 100644
--- a/drivers/iio/dac/Makefile
+++ b/drivers/iio/dac/Makefile
@@ -20,3 +20,4 @@ obj-$(CONFIG_MAX517) += max517.o
obj-$(CONFIG_MAX5821) += max5821.o
obj-$(CONFIG_MCP4725) += mcp4725.o
obj-$(CONFIG_MCP4922) += mcp4922.o
+obj-$(CONFIG_TI_DAC8554) += ti-dac8554.o
diff --git a/drivers/iio/dac/ti-dac8554.c b/drivers/iio/dac/ti-dac8554.c
new file mode 100644
index 0000000..fca751f
--- /dev/null
+++ b/drivers/iio/dac/ti-dac8554.c
@@ -0,0 +1,374 @@
+/*
+ * TI DAC8554 Digital to Analog Converter SPI driver
+ *
+ * Copyright (C) 2014 Avionic Design GmbH
+ *
+ * Based on ad5446r_spi.c
+ * Copyright (C) 2010,2011 Analog Devices Inc.
+ *
+ * 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/spi/spi.h>
+#include <linux/regulator/consumer.h>
+#include <linux/module.h>
+#include <linux/iio/iio.h>
+#include <linux/of.h>
+
+#define DAC8554_DRIVERNAME "ti-dac8554"
+#define DAC8554_DAC_CHANNELS 4
+
+/* Load commands */
+#define DAC8554_CMD_STORE_DAC_N 0x0
+#define DAC8554_CMD_UPDATE_DAC_N 0x1
+#define DAC8554_CMD_STORE_DAC_N_UPDATE_ALL 0x2
+#define DAC8554_CMD_UPDATE_BROADCAST 0x3
+
+#define DAC8554_BROADCAST_USE_SRDATA 0x2
+/* Powerdown modes (ORed PD1|PD2 bits) */
+#define DAC8554_PWRDN_HIZ 0x0
+#define DAC8554_PWRDN_1K 0x1
+#define DAC8554_PWRDN_100K 0x2
+
+#define DAC8554_PWRDN_TO_SR(mode) (BIT(16) | (mode) << 14)
+
+/**
+ * struct dac8554_state - driver instance specific data
+ * @spi: spi_device
+ * @reg: supply regulator
+ * @addr: two-bit chip address
+ * @vref_mv: reference voltage in millivolt
+ * @val DAC/channel data
+ * @powerdown channel powerdown flag
+ * @powerdown_mode channel powerdown mode
+ * @xfer SPI transfer buffer
+ */
+struct dac8554_state {
+ struct spi_device *spi;
+ struct regulator *reg;
+ unsigned addr;
+ unsigned vref_mv;
+ u16 val[DAC8554_DAC_CHANNELS];
+ bool powerdown[DAC8554_DAC_CHANNELS];
+ u8 powerdown_mode[DAC8554_DAC_CHANNELS];
+
+ /*
+ * DMA (thus cache coherency maintenance) requires the
+ * transfer buffers to live in their own cache lines.
+ */
+ u8 xfer[3] ____cacheline_aligned;
+};
+
+static int dac8554_spi_write(struct dac8554_state *st,
+ unsigned cmd,
+ unsigned chan_addr,
+ unsigned val)
+{
+ u32 data;
+
+ /*
+ * The input shift register is 24 bits wide. The 8 MSB are
+ * control bits, followed by 16 data bits.
+ * The first two bits A1 and A0 address a DAC8554 chip.
+ * The next two are the command bits, LD1 and LD0.
+ * After a don't-care-bit, the next two bits select the channel.
+ * The final control bit PD0 is a flag signalling if the data
+ * bits encode a powerdown mode. We merge PD0 with the adjacent
+ * data bits.
+ */
+
+ if (cmd > 3 || chan_addr > 3 ||
+ (val > 0xffff && (val & ~DAC8554_PWRDN_TO_SR(3))))
+ return -EINVAL;
+
+ data = (st->addr << 22) | (cmd << 20) | (chan_addr << 17) | val;
+ st->xfer[0] = data >> 16;
+ st->xfer[1] = data >> 8;
+ st->xfer[2] = data;
+
+ return spi_write(st->spi, st->xfer, sizeof(st->xfer));
+}
+
+static int dac8554_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val,
+ int *val2,
+ long m)
+{
+ struct dac8554_state *st = iio_priv(indio_dev);
+
+ switch (m) {
+ case IIO_CHAN_INFO_RAW:
+ *val = st->val[chan->address];
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_SCALE:
+ *val = st->vref_mv;
+ *val2 = 16;
+ return IIO_VAL_FRACTIONAL_LOG2;
+ }
+ return -EINVAL;
+}
+
+static int dac8554_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int val,
+ int val2,
+ long mask)
+{
+ struct dac8554_state *st = iio_priv(indio_dev);
+ int err;
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ if (val > 0xffff || val < 0)
+ return -EINVAL;
+
+ err = dac8554_spi_write(st, DAC8554_CMD_UPDATE_DAC_N,
+ chan->address, val);
+ if (err)
+ return err;
+
+ st->val[chan->address] = val;
+
+ /* By hw design, DAC updates automatically trigger powerup. */
+ st->powerdown[chan->address] = false;
+
+ return 0;
+
+ default:
+ return -EINVAL;
+ }
+}
+
+static int dac8554_get_powerdown_mode(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan)
+{
+ struct dac8554_state *st = iio_priv(indio_dev);
+
+ return st->powerdown_mode[chan->address];
+}
+
+static int dac8554_set_powerdown_mode(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan,
+ unsigned int mode)
+{
+ struct dac8554_state *st = iio_priv(indio_dev);
+
+ st->powerdown_mode[chan->address] = mode;
+
+ return 0;
+}
+
+static ssize_t dac8554_read_dac_powerdown(struct iio_dev *indio_dev,
+ uintptr_t private,
+ const struct iio_chan_spec *chan,
+ char *buf)
+{
+ struct dac8554_state *st = iio_priv(indio_dev);
+
+ return sprintf(buf, "%d\n", st->powerdown[chan->address]);
+}
+
+static ssize_t dac8554_write_dac_powerdown(struct iio_dev *indio_dev,
+ uintptr_t private,
+ const struct iio_chan_spec *chan,
+ const char *buf,
+ size_t len)
+{
+ bool powerdown;
+ int ret;
+ struct dac8554_state *st = iio_priv(indio_dev);
+ u8 powerdown_mode;
+
+ ret = strtobool(buf, &powerdown);
+ if (ret)
+ return ret;
+
+ st->powerdown[chan->address] = powerdown;
+
+ if (powerdown) {
+ powerdown_mode = st->powerdown_mode[chan->address];
+ ret = dac8554_spi_write(st,
+ DAC8554_CMD_UPDATE_DAC_N,
+ chan->address,
+ DAC8554_PWRDN_TO_SR(powerdown_mode));
+ } else {
+ /* Load DAC with cached value. This triggers a powerup. */
+ ret = dac8554_spi_write(st,
+ DAC8554_CMD_UPDATE_DAC_N,
+ chan->address,
+ st->val[chan->address]);
+ }
+
+ if (ret)
+ return ret;
+
+ return len;
+}
+
+static int dac8554_powerdown(struct dac8554_state *st,
+ u8 powerdown_mode)
+{
+ int chan, cmd, ret;
+
+ for (chan = DAC8554_DAC_CHANNELS-1; chan >= 0; --chan) {
+ cmd = chan ? DAC8554_CMD_STORE_DAC_N
+ : DAC8554_CMD_STORE_DAC_N_UPDATE_ALL;
+ ret = dac8554_spi_write(st, cmd, chan,
+ DAC8554_PWRDN_TO_SR(powerdown_mode));
+ if (ret)
+ return ret;
+ }
+
+ memset(st->powerdown_mode, powerdown_mode, sizeof(st->powerdown_mode));
+ memset(st->powerdown, true, sizeof(st->powerdown));
+
+ return 0;
+}
+
+static const struct iio_info dac8554_info = {
+ .write_raw = dac8554_write_raw,
+ .read_raw = dac8554_read_raw,
+ .driver_module = THIS_MODULE,
+};
+
+static const char * const dac8554_powerdown_modes[] = {
+ "three_state",
+ "1kohm_to_gnd",
+ "100kohm_to_gnd"
+};
+
+static const struct iio_enum dac8854_powerdown_mode_enum = {
+ .items = dac8554_powerdown_modes,
+ .num_items = ARRAY_SIZE(dac8554_powerdown_modes),
+ .get = dac8554_get_powerdown_mode,
+ .set = dac8554_set_powerdown_mode,
+};
+
+static const struct iio_chan_spec_ext_info dac8554_ext_info[] = {
+ {
+ .name = "powerdown",
+ .read = dac8554_read_dac_powerdown,
+ .write = dac8554_write_dac_powerdown,
+ .shared = IIO_SEPARATE,
+ },
+ IIO_ENUM("powerdown_mode", IIO_SEPARATE,
+ &dac8854_powerdown_mode_enum),
+ IIO_ENUM_AVAILABLE("powerdown_mode", &dac8854_powerdown_mode_enum),
+ { },
+};
+
+#define DAC8554_CHANNEL(chan) { \
+ .type = IIO_VOLTAGE, \
+ .indexed = 1, \
+ .output = 1, \
+ .channel = (chan), \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+ .address = (chan), \
+ .ext_info = dac8554_ext_info, \
+}
+const struct iio_chan_spec dac8554_channels[] = {
+ DAC8554_CHANNEL(0),
+ DAC8554_CHANNEL(1),
+ DAC8554_CHANNEL(2),
+ DAC8554_CHANNEL(3),
+};
+#undef DAC8554_CHANNEL
+
+static int dac8554_probe(struct spi_device *spi)
+{
+ struct dac8554_state *st;
+ struct iio_dev *indio_dev;
+ int ret, voltage_uv;
+ u32 addr;
+
+ indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ indio_dev->dev.parent = &spi->dev;
+ indio_dev->name = DAC8554_DRIVERNAME;
+ indio_dev->info = &dac8554_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->channels = dac8554_channels;
+ indio_dev->num_channels = ARRAY_SIZE(dac8554_channels);
+
+ spi_set_drvdata(spi, indio_dev);
+
+ st = iio_priv(indio_dev);
+
+ if (!spi->dev.of_node) {
+ dev_err(&spi->dev, "missing OF node");
+ return -ENODEV;
+ }
+ ret = of_property_read_u32(spi->dev.of_node, "address", &addr);
+ if (ret || addr < 0 || addr > 2) {
+ dev_err(&spi->dev, "no or invalid chip address");
+ return -ENODEV;
+ }
+
+ st->spi = spi;
+ st->addr = addr;
+
+ st->reg = devm_regulator_get(&spi->dev, "vref");
+ if (IS_ERR(st->reg))
+ return PTR_ERR(st->reg);
+
+ ret = regulator_enable(st->reg);
+ if (ret)
+ return ret;
+
+ voltage_uv = regulator_get_voltage(st->reg);
+ if (voltage_uv < 0)
+ goto error_disable_reg;
+ st->vref_mv = voltage_uv / 1000;
+
+ ret = dac8554_powerdown(st, DAC8554_PWRDN_100K);
+ if (ret)
+ goto error_disable_reg;
+
+ ret = iio_device_register(indio_dev);
+ if (ret)
+ goto error_disable_reg;
+
+ return 0;
+
+error_disable_reg:
+ regulator_disable(st->reg);
+ return ret;
+}
+
+static int dac8554_remove(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev = spi_get_drvdata(spi);
+ struct dac8554_state *st = iio_priv(indio_dev);
+
+ iio_device_unregister(indio_dev);
+ regulator_disable(st->reg);
+
+ return 0;
+}
+
+static const struct of_device_id dac8554_of_match[] = {
+ { .compatible = "ti,dac8554" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, dac8554_of_match);
+
+static struct spi_driver dac8554_driver = {
+ .driver = {
+ .name = DAC8554_DRIVERNAME,
+ .owner = THIS_MODULE,
+ .of_match_table = dac8554_of_match,
+ },
+ .probe = dac8554_probe,
+ .remove = dac8554_remove,
+};
+module_spi_driver(dac8554_driver);
+
+MODULE_AUTHOR("Nikolaus Schulz <nikolaus.sch...@avionic-design.de>");
+MODULE_DESCRIPTION("Texas Instruments DAC8554 SPI driver");
+MODULE_LICENSE("GPL v2");
--
2.1.3
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