[PATCH 1/3] iio: dac: add support for ltc2688

Nuno Sá
2021-12-14T16:57:00Z

The LTC2688 is a 16 channel, 16 bit, +-15V DAC with an integrated
precision reference. It is guaranteed monotonic and has built in
rail-to-rail output buffers that can source or sink up to 20 mA.

Signed-off-by: Nuno Sá <nuno.sa@analog.com>
---
MAINTAINERS | 7 +
drivers/iio/dac/Kconfig | 11 +
drivers/iio/dac/Makefile | 1 +
drivers/iio/dac/ltc2688.c | 1081 +++++++++++++++++++++++++++++++++++++
4 files changed, 1100 insertions(+)
create mode 100644 drivers/iio/dac/ltc2688.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 57fb0f19ee08..90960e3d778f 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -11162,6 +11162,13 @@ S: Maintained
F: Documentation/devicetree/bindings/iio/dac/lltc,ltc1660.yaml
F: drivers/iio/dac/ltc1660.c

+LTC2688 IIO DAC DRIVER
+M: Nuno Sá <nuno.sa@analog.com>
+L: linux-iio@vger.kernel.org
+S: Supported
+W: http://ez.analog.com/community/linux-device-drivers
+F: drivers/iio/dac/ltc2688.c
+
LTC2947 HARDWARE MONITOR DRIVER
M: Nuno Sá <nuno.sa@analog.com>
L: linux-hwmon@vger.kernel.org
diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
index b95619f18fa5..cf503fa93381 100644
--- a/drivers/iio/dac/Kconfig
+++ b/drivers/iio/dac/Kconfig
@@ -121,6 +121,17 @@ config AD5624R_SPI
Say yes here to build support for Analog Devices AD5624R, AD5644R and
AD5664R converters (DAC). This driver uses the common SPI interface.

+config LTC2688
+ tristate "Analog Devices LTC2688 DAC spi driver"
+ depends on SPI
+ select REGMAP
+ help
+ Say yes here to build support for Analog Devices
+ LTC2688 converters (DAC).
+
+ To compile this driver as a module, choose M here: the
+ module will be called ltc2688.
+
config AD5686
tristate

diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
index 3c17246ee89b..5904edfb8ddc 100644
--- a/drivers/iio/dac/Makefile
+++ b/drivers/iio/dac/Makefile
@@ -34,6 +34,7 @@ obj-$(CONFIG_DS4424) += ds4424.o
obj-$(CONFIG_LPC18XX_DAC) += lpc18xx_dac.o
obj-$(CONFIG_LTC1660) += ltc1660.o
obj-$(CONFIG_LTC2632) += ltc2632.o
+obj-$(CONFIG_LTC2688) += ltc2688.o
obj-$(CONFIG_M62332) += m62332.o
obj-$(CONFIG_MAX517) += max517.o
obj-$(CONFIG_MAX5821) += max5821.o
diff --git a/drivers/iio/dac/ltc2688.c b/drivers/iio/dac/ltc2688.c
new file mode 100644
index 000000000000..895a0dbe35af
--- /dev/null
+++ b/drivers/iio/dac/ltc2688.c
@@ -0,0 +1,1081 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * LTC2688 16 channel, 16 bit Voltage Output SoftSpan DAC driver
+ *
+ * Copyright 2021 Analog Devices Inc.
+ */
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <linux/limits.h>
+#include <linux/iio/iio.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/mutex.h>
+#include <linux/kernel.h>
+#include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
+#include <linux/spi/spi.h>
+
+#define LTC2688_DAC_CHANNELS 16
+
+#define LTC2688_CMD_CH_CODE(x) (0x00 + (x))
+#define LTC2688_CMD_CH_SETTING(x) (0x10 + (x))
+#define LTC2688_CMD_CH_OFFSET(x) (0X20 + (x))
+#define LTC2688_CMD_CH_GAIN(x) (0x30 + (x))
+#define LTC2688_CMD_CH_CODE_UPDATE(x) (0x40 + (x))
+
+#define LTC2688_CMD_CONFIG 0x70
+#define LTC2688_CMD_POWERDOWN 0x71
+#define LTC2688_CMD_A_B_SELECT 0x72
+#define LTC2688_CMD_SW_TOGGLE 0x73
+#define LTC2688_CMD_TOGGLE_DITHER_EN 0x74
+#define LTC2688_CMD_THERMAL_STAT 0x77
+#define LTC2688_CMD_UPDATE_ALL 0x7C
+#define LTC2688_CMD_NOOP 0xFF
+
+#define LTC2688_READ_OPERATION 0x80
+
+/* Channel Settings */
+#define LTC2688_CH_SPAN_MSK GENMASK(2, 0)
+#define LTC2688_CH_OVERRANGE_MSK BIT(3)
+#define LTC2688_CH_TD_SEL_MSK GENMASK(5, 4)
+#define LTC2688_CH_DIT_PER_MSK GENMASK(8, 6)
+#define LTC2688_CH_DIT_PH_MSK GENMASK(10, 9)
+#define LTC2688_CH_MODE_MSK BIT(11)
+
+/* Configuration register */
+#define LTC2688_CONFIG_RST BIT(15)
+#define LTC2688_CONFIG_EXT_REF BIT(1)
+
+#define LTC2688_DITHER_FREQ_AVAIL_N 5
+
+enum {
+ LTC2688_SPAN_RANGE_0V_5V,
+ LTC2688_SPAN_RANGE_0V_10V,
+ LTC2688_SPAN_RANGE_M5V_5V,
+ LTC2688_SPAN_RANGE_M10V_10V,
+ LTC2688_SPAN_RANGE_M15V_15V,
+ LTC2688_SPAN_RANGE_MAX
+};
+
+enum {
+ LTC2688_MODE_DEFAULT,
+ LTC2688_MODE_DITHER_TOGGLE,
+};
+
+struct ltc2688_chan {
+ long dither_frequency[LTC2688_DITHER_FREQ_AVAIL_N];
+ bool overrange;
+ bool toggle_chan;
+ u8 mode;
+};
+
+struct ltc2688_state {
+ struct spi_device *spi;
+ struct regmap *regmap;
+ struct regulator_bulk_data regulators[2];
+ struct ltc2688_chan channels[LTC2688_DAC_CHANNELS];
+ /* lock to protect against multiple access to the device and shared data */
+ struct mutex lock;
+ int vref;
+ /*
+ * DMA (thus cache coherency maintenance) requires the
+ * transfer buffers to live in their own cache lines.
+ */
+ u8 tx_data[3] ____cacheline_aligned;
+ u8 rx_data[3];
+};
+
+static int ltc2688_spi_read(void *context, const void *reg, size_t reg_size,
+ void *val, size_t val_size)
+{
+ struct ltc2688_state *st = context;
+ struct spi_transfer xfers[] = {
+ {
+ .tx_buf = reg,
+ .bits_per_word = 8,
+ /*
+ * This means that @val will also be part of the
+ * transfer as there's no pad bits. That's fine as these
+ * bits are don't care for the device and we fill
+ * @val with the proper value afterwards. Using regmap
+ * pad bits to get reg_size right would just make the
+ * write part more cumbersome than this...
+ */
+ .len = reg_size + 2,
+ .cs_change = 1,
+ }, {
+ .tx_buf = st->tx_data,
+ .rx_buf = st->rx_data,
+ .bits_per_word = 8,
+ .len = 3,
+ },
+ };
+ int ret;
+
+ ret = spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers));
+ if (ret)
+ return ret;
+
+ memcpy(val, &st->rx_data[1], val_size);
+
+ return 0;
+}
+
+static int ltc2688_spi_write(void *context, const void *data, size_t count)
+{
+ struct ltc2688_state *st = context;
+
+ return spi_write(st->spi, data, count);
+}
+
+static int ltc2688_span_get(const struct ltc2688_state *st, int c)
+{
+ int ret, reg, span;
+
+ ret = regmap_read(st->regmap, LTC2688_CMD_CH_SETTING(c), &reg);
+ if (ret)
+ return ret;
+
+ span = FIELD_GET(LTC2688_CH_SPAN_MSK, reg);
+ /* sanity check to make sure we don't get any weird value from the HW */
+ if (span >= LTC2688_SPAN_RANGE_MAX)
+ return -EIO;
+
+ return span;
+}
+
+static const int ltc2688_span_helper[LTC2688_SPAN_RANGE_MAX][2] = {
+ {0, 5000}, {0, 10000}, {-5000, 5000}, {-10000, 10000}, {-15000, 15000},
+};
+
+static int ltc2688_scale_get(const struct ltc2688_state *st, int c, int *val)
+{
+ const struct ltc2688_chan *chan = &st->channels[c];
+ int span, fs;
+
+ span = ltc2688_span_get(st, c);
+ if (span < 0)
+ return span;
+
+ fs = ltc2688_span_helper[span][1] - ltc2688_span_helper[span][0];
+ if (chan->overrange)
+ fs = mult_frac(fs, 105, 100);
+
+ *val = DIV_ROUND_CLOSEST(fs * st->vref, 4096);
+
+ return IIO_VAL_FRACTIONAL_LOG2;
+}
+
+static int ltc2688_offset_get(const struct ltc2688_state *st, int c, int *val)
+{
+ int span;
+
+ span = ltc2688_span_get(st, c);
+ if (span < 0)
+ return span;
+
+ if (ltc2688_span_helper[span][0] < 0)
+ *val = -32768;
+ else
+ *val = 0;
+
+ return IIO_VAL_INT;
+}
+
+enum {
+ LT2688_INPUT_A,
+ LT2688_INPUT_B,
+};
+
+static int ltc2688_dac_code_write(struct ltc2688_state *st, u32 chan, u32 input,
+ u16 code)
+{
+ struct ltc2688_chan *c = &st->channels[chan];
+ int ret, reg;
+
+ /* 2 LSBs set to 0 if writing dither amplitude */
+ if (!c->toggle_chan && input == LT2688_INPUT_B) {
+ if (code > GENMASK(13, 0))
+ return -EINVAL;
+
+ code <<= 2;
+ }
+
+ mutex_lock(&st->lock);
+ /* select the correct input register to read from */
+ ret = regmap_update_bits(st->regmap, LTC2688_CMD_A_B_SELECT, BIT(chan),
+ input << chan);
+ if (ret)
+ goto unlock;
+
+ /*
+ * If in dither/toggle mode the dac should be updated by an
+ * external signal (or sw toggle) and not here.
+ */
+ if (c->mode == LTC2688_MODE_DEFAULT)
+ reg = LTC2688_CMD_CH_CODE_UPDATE(chan);
+ else
+ reg = LTC2688_CMD_CH_CODE(chan);
+
+ ret = regmap_write(st->regmap, reg, code);
+unlock:
+ mutex_unlock(&st->lock);
+ return ret;
+}
+
+static int ltc2688_dac_code_read(struct ltc2688_state *st, u32 chan, u32 input,
+ u32 *code)
+{
+ struct ltc2688_chan *c = &st->channels[chan];
+ int ret;
+
+ mutex_lock(&st->lock);
+ ret = regmap_update_bits(st->regmap, LTC2688_CMD_A_B_SELECT, BIT(chan),
+ input << chan);
+ if (ret)
+ goto unlock;
+
+ ret = regmap_read(st->regmap, LTC2688_CMD_CH_CODE(chan), code);
+unlock:
+ mutex_unlock(&st->lock);
+
+ if (!c->toggle_chan && input == LT2688_INPUT_B)
+ *code >>= 2;
+
+ return ret;
+}
+
+static const int ltc2688_raw_range[] = {0, 1, U16_MAX};
+
+static int ltc2688_read_avail(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ const int **vals, int *type, int *length,
+ long m)
+{
+ switch (m) {
+ case IIO_CHAN_INFO_RAW:
+ *vals = ltc2688_raw_range;
+ *type = IIO_VAL_INT;
+ return IIO_AVAIL_RANGE;
+ default:
+ return -EINVAL;
+ }
+}
+
+static int ltc2688_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan, int *val,
+ int *val2, long m)
+{
+ struct ltc2688_state *st = iio_priv(indio_dev);
+ int ret;
+
+ switch (m) {
+ case IIO_CHAN_INFO_RAW:
+ ret = ltc2688_dac_code_read(st, chan->channel, LT2688_INPUT_A,
+ val);
+ if (ret)
+ return ret;
+
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_OFFSET:
+ return ltc2688_offset_get(st, chan->channel, val);
+ case IIO_CHAN_INFO_SCALE:
+ *val2 = 16;
+ return ltc2688_scale_get(st, chan->channel, val);
+ case IIO_CHAN_INFO_CALIBBIAS:
+ ret = regmap_read(st->regmap,
+ LTC2688_CMD_CH_OFFSET(chan->channel), val);
+ if (ret)
+ return ret;
+
+ /* Just 13 bits used. 2LSB ignored */
+ *val >>= 2;
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_CALIBSCALE:
+ ret = regmap_read(st->regmap,
+ LTC2688_CMD_CH_GAIN(chan->channel), val);
+ if (ret)
+ return ret;
+
+ return IIO_VAL_INT;
+ default:
+ return -EINVAL;
+ }
+}
+
+static int ltc2688_write_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan, int val,
+ int val2, long mask)
+{
+ struct ltc2688_state *st = iio_priv(indio_dev);
+
+ switch (mask) {
+ case IIO_CHAN_INFO_RAW:
+ if (val > U16_MAX || val < 0)
+ return -EINVAL;
+
+ return ltc2688_dac_code_write(st, chan->channel, LT2688_INPUT_A,
+ val);
+ case IIO_CHAN_INFO_CALIBBIAS:
+ if (val > GENMASK(13, 0))
+ return -EINVAL;
+
+ return regmap_write(st->regmap,
+ LTC2688_CMD_CH_OFFSET(chan->channel),
+ val << 2);
+ case IIO_CHAN_INFO_CALIBSCALE:
+ return regmap_write(st->regmap,
+ LTC2688_CMD_CH_GAIN(chan->channel), val);
+ default:
+ return -EINVAL;
+ }
+}
+
+enum {
+ LTC2688_DITHER_TOGGLE_ENABLE,
+ LTC2688_POWERDOWN,
+ LTC2688_INPUT_B,
+ LTC2688_INPUT_B_AVAIL,
+ LTC2688_SW_TOGGLE,
+ LTC2688_DITHER_FREQ,
+ LTC2688_DITHER_FREQ_AVAIL,
+};
+
+static int ltc2688_dither_toggle_set(struct ltc2688_state *st, u32 chan, bool en)
+{
+ struct ltc2688_chan *c = &st->channels[chan];
+ int ret;
+
+ mutex_lock(&st->lock);
+ ret = regmap_update_bits(st->regmap, LTC2688_CMD_TOGGLE_DITHER_EN,
+ BIT(chan), en << chan);
+ if (ret)
+ goto unlock;
+
+ c->mode = en ? LTC2688_MODE_DITHER_TOGGLE : LTC2688_MODE_DEFAULT;
+unlock:
+ mutex_unlock(&st->lock);
+
+ return ret;
+}
+
+static ssize_t ltc2688_reg_bool_get(const struct ltc2688_state *st, u32 chan,
+ u32 reg, char *buf)
+{
+ int ret;
+ u32 val;
+
+ ret = regmap_read(st->regmap, reg, &val);
+ if (ret)
+ return ret;
+
+ return sysfs_emit(buf, "%u\n", !!(val & BIT(chan)));
+}
+
+static ssize_t ltc2688_reg_bool_set(const struct ltc2688_state *st, u32 chan,
+ u32 reg, const char *buf)
+{
+ int ret;
+ bool en;
+
+ ret = kstrtobool(buf, &en);
+ if (ret)
+ return ret;
+
+ return regmap_update_bits(st->regmap, reg, BIT(chan), en << chan);
+}
+
+static ssize_t ltc2688_dither_freq_avail(const struct ltc2688_state *st,
+ u32 chan, char *buf)
+{
+ const struct ltc2688_chan *c = &st->channels[chan];
+ int sz = 0;
+ u32 f;
+
+ for (f = 0; f < ARRAY_SIZE(c->dither_frequency); f++)
+ sz += sysfs_emit_at(buf, sz, "%ld ", c->dither_frequency[f]);
+
+ buf[sz - 1] = '\n';
+
+ return sz;
+}
+
+static ssize_t ltc2688_dither_freq_get(const struct ltc2688_state *st, u32 chan,
+ char *buf)
+{
+ const struct ltc2688_chan *c = &st->channels[chan];
+ u32 reg, freq;
+ int ret;
+
+ ret = regmap_read(st->regmap, LTC2688_CMD_CH_SETTING(chan), &reg);
+ if (ret)
+ return ret;
+
+ freq = FIELD_GET(LTC2688_CH_DIT_PER_MSK, reg);
+ if (freq >= ARRAY_SIZE(c->dither_frequency))
+ return -EIO;
+
+ return sysfs_emit(buf, "%ld\n", c->dither_frequency[freq]);
+}
+
+static int ltc2688_dither_freq_set(const struct ltc2688_state *st, u32 chan,
+ const char *buf)
+{
+ const struct ltc2688_chan *c = &st->channels[chan];
+ long val;
+ u32 freq;
+ int ret;
+
+ ret = kstrtol(buf, 10, &val);
+ if (ret)
+ return ret;
+
+ for (freq = 0; freq < ARRAY_SIZE(c->dither_frequency); freq++) {
+ if (val == c->dither_frequency[freq])
+ break;
+ }
+
+ if (freq == ARRAY_SIZE(c->dither_frequency))
+ return -EINVAL;
+
+ return regmap_update_bits(st->regmap,
+ LTC2688_CMD_CH_SETTING(chan),
+ LTC2688_CH_DIT_PER_MSK,
+ FIELD_PREP(LTC2688_CH_DIT_PER_MSK, freq));
+}
+
+static ssize_t ltc2688_read_ext(struct iio_dev *indio_dev,
+ uintptr_t private,
+ const struct iio_chan_spec *chan,
+ char *buf)
+{
+ struct ltc2688_state *st = iio_priv(indio_dev);
+ u32 val;
+ int ret;
+
+ switch (private) {
+ case LTC2688_DITHER_TOGGLE_ENABLE:
+ return ltc2688_reg_bool_get(st, chan->channel,
+ LTC2688_CMD_TOGGLE_DITHER_EN, buf);
+ case LTC2688_POWERDOWN:
+ return ltc2688_reg_bool_get(st, chan->channel,
+ LTC2688_CMD_POWERDOWN, buf);
+ case LTC2688_INPUT_B:
+ ret = ltc2688_dac_code_read(st, chan->channel, LT2688_INPUT_B,
+ &val);
+ if (ret)
+ return ret;
+
+ return sysfs_emit(buf, "%u\n", val);
+ case LTC2688_INPUT_B_AVAIL:
+ /* dither amplitude has 1/4 of the span */
+ return sysfs_emit(buf, "[%u %u %u]\n", ltc2688_raw_range[0],
+ ltc2688_raw_range[1],
+ ltc2688_raw_range[2] / 4);
+ case LTC2688_SW_TOGGLE:
+ return ltc2688_reg_bool_get(st, chan->channel,
+ LTC2688_CMD_SW_TOGGLE, buf);
+ case LTC2688_DITHER_FREQ:
+ return ltc2688_dither_freq_get(st, chan->channel, buf);
+ case LTC2688_DITHER_FREQ_AVAIL:
+ return ltc2688_dither_freq_avail(st, chan->channel, buf);
+ default:
+ return -EINVAL;
+ }
+}
+
+static ssize_t ltc2688_write_ext(struct iio_dev *indio_dev,
+ uintptr_t private,
+ const struct iio_chan_spec *chan,
+ const char *buf, size_t len)
+{
+ struct ltc2688_state *st = iio_priv(indio_dev);
+ u16 val;
+ int ret;
+ bool en;
+
+ switch (private) {
+ case LTC2688_DITHER_TOGGLE_ENABLE:
+ ret = kstrtobool(buf, &en);
+ if (ret)
+ return ret;
+
+ ret = ltc2688_dither_toggle_set(st, chan->channel, en);
+ if (ret)
+ return ret;
+
+ return len;
+ case LTC2688_POWERDOWN:
+ ret = ltc2688_reg_bool_set(st, chan->channel,
+ LTC2688_CMD_POWERDOWN, buf);
+ if (ret)
+ return ret;
+
+ return len;
+ case LTC2688_INPUT_B:
+ ret = kstrtou16(buf, 10, &val);
+ if (ret)
+ return ret;
+
+ ret = ltc2688_dac_code_write(st, chan->channel, LT2688_INPUT_B,
+ val);
+ if (ret)
+ return ret;
+
+ return len;
+ case LTC2688_SW_TOGGLE:
+ ret = ltc2688_reg_bool_set(st, chan->channel,
+ LTC2688_CMD_SW_TOGGLE, buf);
+ if (ret)
+ return ret;
+
+ return len;
+ case LTC2688_DITHER_FREQ:
+ ret = ltc2688_dither_freq_set(st, chan->channel, buf);
+ if (ret)
+ return ret;
+
+ return len;
+ default:
+ return -EINVAL;
+ }
+}
+
+static int ltc2688_get_dither_phase(struct iio_dev *dev,
+ const struct iio_chan_spec *chan)
+{
+ struct ltc2688_state *st = iio_priv(dev);
+ int ret, regval;
+
+ ret = regmap_read(st->regmap, LTC2688_CMD_CH_SETTING(chan->channel),
+ &regval);
+ if (ret)
+ return ret;
+
+ return FIELD_GET(LTC2688_CH_DIT_PH_MSK, regval);
+}
+
+static int ltc2688_set_dither_phase(struct iio_dev *dev,
+ const struct iio_chan_spec *chan,
+ unsigned int phase)
+{
+ struct ltc2688_state *st = iio_priv(dev);
+
+ return regmap_update_bits(st->regmap,
+ LTC2688_CMD_CH_SETTING(chan->channel),
+ LTC2688_CH_DIT_PH_MSK,
+ FIELD_PREP(LTC2688_CH_DIT_PH_MSK, phase));
+}
+
+static int ltc2688_reg_access(struct iio_dev *indio_dev,
+ unsigned int reg,
+ unsigned int writeval,
+ unsigned int *readval)
+{
+ struct ltc2688_state *st = iio_priv(indio_dev);
+
+ if (readval)
+ return regmap_read(st->regmap, reg, readval);
+ else
+ return regmap_write(st->regmap, reg, writeval);
+}
+
+static const char * const ltc2688_dither_phase[] = {
+ "0", "90", "180", "270",
+};
+
+static const struct iio_enum ltc2688_dither_phase_enum = {
+ .items = ltc2688_dither_phase,
+ .num_items = ARRAY_SIZE(ltc2688_dither_phase),
+ .set = ltc2688_set_dither_phase,
+ .get = ltc2688_get_dither_phase,
+};
+
+#define LTC2688_CHAN_EXT_INFO(_name, _what, _shared) { \
+ .name = _name, \
+ .read = ltc2688_read_ext, \
+ .write = ltc2688_write_ext, \
+ .private = (_what), \
+ .shared = (_shared), \
+}
+
+/*
+ * For toggle mode we only expose the symbol attr (sw_toggle) in case a TGPx is
+ * not provided in dts.
+ */
+#define LTC2688_CHAN_TOGGLE(t, name) ({ \
+ static const struct iio_chan_spec_ext_info t ## _ext_info[] = { \
+ LTC2688_CHAN_EXT_INFO("raw1", LTC2688_INPUT_B, IIO_SEPARATE), \
+ LTC2688_CHAN_EXT_INFO("toggle_en", LTC2688_DITHER_TOGGLE_ENABLE, \
+ IIO_SEPARATE), \
+ LTC2688_CHAN_EXT_INFO("powerdown", LTC2688_POWERDOWN, IIO_SEPARATE), \
+ LTC2688_CHAN_EXT_INFO(name, LTC2688_SW_TOGGLE, IIO_SEPARATE), \
+ {} \
+ }; \
+ t ## _ext_info; \
+})
+
+static struct iio_chan_spec_ext_info ltc2688_dither_ext_info[] = {
+ LTC2688_CHAN_EXT_INFO("dither_raw", LTC2688_INPUT_B, IIO_SEPARATE),
+ LTC2688_CHAN_EXT_INFO("dither_raw_available", LTC2688_INPUT_B_AVAIL,
+ IIO_SEPARATE),
+ /*
+ * Not IIO_ENUM because the available freq needs to be computed at
+ * probe. We could still use it, but it didn't felt much right.
+ *
+ */
+ LTC2688_CHAN_EXT_INFO("dither_frequency", LTC2688_DITHER_FREQ,
+ IIO_SEPARATE),
+ LTC2688_CHAN_EXT_INFO("dither_frequency_available",
+ LTC2688_DITHER_FREQ_AVAIL, IIO_SEPARATE),
+ IIO_ENUM("dither_phase", IIO_SEPARATE, &ltc2688_dither_phase_enum),
+ IIO_ENUM_AVAILABLE("dither_phase", IIO_SEPARATE,
+ &ltc2688_dither_phase_enum),
+ LTC2688_CHAN_EXT_INFO("dither_en", LTC2688_DITHER_TOGGLE_ENABLE,
+ IIO_SEPARATE),
+ LTC2688_CHAN_EXT_INFO("powerdown", LTC2688_POWERDOWN, IIO_SEPARATE),
+ {}
+};
+
+static const struct iio_chan_spec_ext_info ltc2688_ext_info[] = {
+ LTC2688_CHAN_EXT_INFO("powerdown", LTC2688_POWERDOWN, IIO_SEPARATE),
+ {}
+};
+
+#define LTC2688_CHANNEL(_chan) { \
+ .type = IIO_VOLTAGE, \
+ .indexed = 1, \
+ .output = 1, \
+ .channel = (_chan), \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_CALIBSCALE) | \
+ BIT(IIO_CHAN_INFO_SCALE) | BIT(IIO_CHAN_INFO_OFFSET) | \
+ BIT(IIO_CHAN_INFO_CALIBBIAS) | BIT(IIO_CHAN_INFO_RAW), \
+ .info_mask_separate_available = BIT(IIO_CHAN_INFO_RAW), \
+ .ext_info = ltc2688_ext_info \
+}
+
+struct iio_chan_spec ltc2688_channels[] = {
+ LTC2688_CHANNEL(0),
+ LTC2688_CHANNEL(1),
+ LTC2688_CHANNEL(2),
+ LTC2688_CHANNEL(3),
+ LTC2688_CHANNEL(4),
+ LTC2688_CHANNEL(5),
+ LTC2688_CHANNEL(6),
+ LTC2688_CHANNEL(7),
+ LTC2688_CHANNEL(8),
+ LTC2688_CHANNEL(9),
+ LTC2688_CHANNEL(10),
+ LTC2688_CHANNEL(11),
+ LTC2688_CHANNEL(12),
+ LTC2688_CHANNEL(13),
+ LTC2688_CHANNEL(14),
+ LTC2688_CHANNEL(15),
+};
+
+enum {
+ LTC2688_CHAN_TD_TGP1,
+ LTC2688_CHAN_TD_TGP2,
+ LTC2688_CHAN_TD_TGP3,
+ LTC2688_CHAN_TD_MAX
+};
+
+static void ltc2688_clk_disable(void *clk)
+{
+ clk_disable_unprepare(clk);
+}
+
+/* Helper struct to deal with dither channels binded to TGPx pins */
+struct ltc2688_dither_helper {
+ u8 chan[LTC2688_DAC_CHANNELS];
+ u8 n_chans;
+};
+
+static const char * const ltc2688_clk_names[LTC2688_CHAN_TD_MAX] = {
+ "TGP1", "TGP2", "TGP3",
+};
+
+static const int ltc2688_period[LTC2688_DITHER_FREQ_AVAIL] = {
+ 4, 8, 16, 32, 64,
+};
+
+static void ltc2688_dither_compute_freq_avail(struct ltc2688_state *st,
+ const struct ltc2688_dither_helper *tgp,
+ unsigned long rate)
+{
+ u32 e;
+
+ for (e = 0; e < tgp->n_chans; e++) {
+ int c = tgp->chan[e];
+ struct ltc2688_chan *chan = &st->channels[c];
+ u32 f;
+
+ for (f = 0; f < ARRAY_SIZE(chan->dither_frequency); f++)
+ chan->dither_frequency[f] = DIV_ROUND_CLOSEST(rate, ltc2688_period[f]);
+ }
+}
+
+static int ltc2688_tgp_setup(struct ltc2688_state *st, long clk_mask,
+ const struct ltc2688_dither_helper *tgp)
+{
+ int ret, bit;
+
+ for_each_set_bit(bit, &clk_mask, LTC2688_CHAN_TD_MAX) {
+ struct clk *clk;
+ unsigned long rate;
+
+ clk = devm_clk_get(&st->spi->dev, ltc2688_clk_names[bit]);
+ if (IS_ERR(clk))
+ return dev_err_probe(&st->spi->dev, PTR_ERR(clk),
+ "failed to get clk: %s\n",
+ ltc2688_clk_names[bit]);
+
+ ret = clk_prepare_enable(clk);
+ if (ret)
+ return dev_err_probe(&st->spi->dev, ret,
+ "failed to enable clk: %s\n",
+ ltc2688_clk_names[bit]);
+
+ ret = devm_add_action_or_reset(&st->spi->dev,
+ ltc2688_clk_disable, clk);
+ if (ret)
+ return ret;
+
+ /* this will only be non zero for dither channels */
+ if (!tgp[bit].n_chans)
+ continue;
+
+ rate = clk_get_rate(clk);
+ ltc2688_dither_compute_freq_avail(st, &tgp[bit], rate);
+ }
+
+ return 0;
+}
+
+static int ltc2688_span_lookup(const struct ltc2688_state *st, int min, int max)
+{
+ u32 span;
+
+ for (span = 0; span < ARRAY_SIZE(ltc2688_span_helper); span++) {
+ if (min == ltc2688_span_helper[span][0] &&
+ max == ltc2688_span_helper[span][1])
+ return span;
+ }
+
+ return -EINVAL;
+}
+
+static int ltc2688_channel_config(struct ltc2688_state *st)
+{
+ struct fwnode_handle *fwnode = dev_fwnode(&st->spi->dev), *child;
+ struct ltc2688_dither_helper tgp[LTC2688_CHAN_TD_MAX] = {0};
+ u32 reg, clk_input, val, mask, tmp[2];
+ unsigned long clk_msk = 0;
+ int ret, span;
+
+ fwnode_for_each_available_child_node(fwnode, child) {
+ struct ltc2688_chan *chan;
+
+ ret = fwnode_property_read_u32(child, "reg", &reg);
+ if (ret) {
+ fwnode_handle_put(child);
+ return dev_err_probe(&st->spi->dev, ret,
+ "Failed to get reg property\n");
+ }
+
+ if (reg >= LTC2688_DAC_CHANNELS) {
+ fwnode_handle_put(child);
+ return dev_err_probe(&st->spi->dev, -EINVAL,
+ "reg bigger than: %d\n",
+ LTC2688_DAC_CHANNELS);
+ }
+
+ chan = &st->channels[reg];
+ if (fwnode_property_read_bool(child, "adi,toggle-mode")) {
+ chan->toggle_chan = true;
+ /* assume sw toggle ABI */
+ ltc2688_channels[reg].ext_info = LTC2688_CHAN_TOGGLE(__s, "symbol");
+ }
+
+ ret = fwnode_property_read_u32_array(child, "adi,output-range-millivolt",
+ tmp, ARRAY_SIZE(tmp));
+ if (!ret) {
+ span = ltc2688_span_lookup(st, tmp[0], tmp[1]);
+ if (span < 0)
+ return dev_err_probe(&st->spi->dev, -EINVAL,
+ "output range not valid:[%d %d]\n",
+ tmp[0], tmp[1]);
+
+ mask |= LTC2688_CH_SPAN_MSK;
+ val |= FIELD_PREP(LTC2688_CH_SPAN_MSK, span);
+ }
+
+ ret = fwnode_property_read_u32(child, "adi,toggle-dither-input",
+ &clk_input);
+ if (!ret) {
+ int cur_chan = tgp[clk_input].n_chans;
+
+ if (clk_input > LTC2688_CHAN_TD_TGP3) {
+ fwnode_handle_put(child);
+ return dev_err_probe(&st->spi->dev, -EINVAL,
+ "toggle-dither-input inv value(%d)\n",
+ clk_input);
+ }
+
+ mask |= LTC2688_CH_TD_SEL_MSK;
+ /*
+ * 0 means software toggle which is the default mode.
+ * Hence the +1.
+ */
+ val |= FIELD_PREP(LTC2688_CH_TD_SEL_MSK, clk_input + 1);
+ clk_msk |= BIT(clk_input);
+ /*
+ * If a TGPx is given, we automatically assume a dither
+ * capable channel (unless toggle is already enabled).
+ * Hence, we prepar our TGPx <-> channel map to make it
+ * easier to handle the clocks and available frequency
+ * calculations... On top of this we just set here the
+ * dither bit in the channel settings. It won't have any
+ * effect until the global toggle/dither bit is enabled.
+ */
+ if (!chan->toggle_chan) {
+ tgp[clk_input].chan[cur_chan] = reg;
+ tgp[clk_input].n_chans++;
+ mask |= LTC2688_CH_MODE_MSK;
+ val |= FIELD_PREP(LTC2688_CH_MODE_MSK, 1);
+ ltc2688_channels[reg].ext_info = ltc2688_dither_ext_info;
+ } else {
+ /* wait, no sw toggle after all */
+ ltc2688_channels[reg].ext_info = LTC2688_CHAN_TOGGLE(__no_s, NULL);
+ }
+ }
+
+ if (fwnode_property_read_bool(child, "adi,overrange")) {
+ chan->overrange = true;
+ val |= LTC2688_CH_OVERRANGE_MSK;
+ mask |= BIT(3);
+ }
+
+ if (!mask)
+ continue;
+
+ ret = regmap_update_bits(st->regmap,
+ LTC2688_CMD_CH_SETTING(reg), mask,
+ val);
+ if (ret) {
+ fwnode_handle_put(child);
+ return dev_err_probe(&st->spi->dev, -EINVAL,
+ "failed to set chan settings\n");
+ }
+
+ mask = 0;
+ val = 0;
+ }
+
+ return ltc2688_tgp_setup(st, clk_msk, tgp);
+}
+
+static int ltc2688_setup(struct ltc2688_state *st, struct regulator *vref)
+{
+ struct gpio_desc *gpio;
+ int ret;
+
+ /*
+ * If we have a reset pin, use that to reset the board, If not, use
+ * the reset bit.
+ */
+ gpio = devm_gpiod_get_optional(&st->spi->dev, "reset", GPIOD_OUT_HIGH);
+ if (IS_ERR(gpio))
+ return dev_err_probe(&st->spi->dev, PTR_ERR(gpio),
+ "Failed to get reset gpio");
+ if (gpio) {
+ usleep_range(1000, 1200);
+ /* bring device out of reset */
+ gpiod_set_value_cansleep(gpio, 0);
+ } else {
+ ret = regmap_update_bits(st->regmap, LTC2688_CMD_CONFIG,
+ LTC2688_CONFIG_RST,
+ LTC2688_CONFIG_RST);
+ if (ret < 0)
+ return ret;
+ }
+
+ usleep_range(10000, 12000);
+
+ ret = ltc2688_channel_config(st);
+ if (ret)
+ return ret;
+
+ if (!vref)
+ return 0;
+
+ return regmap_update_bits(st->regmap, LTC2688_CMD_CONFIG,
+ LTC2688_CONFIG_EXT_REF, BIT(1));
+}
+
+static void ltc2688_bulk_disable(void *data)
+{
+ struct ltc2688_state *st = data;
+
+ regulator_bulk_disable(ARRAY_SIZE(st->regulators), st->regulators);
+}
+
+static void ltc2688_disable_regulator(void *regulator)
+{
+ regulator_disable(regulator);
+}
+
+static bool ltc2688_reg_readable(struct device *dev, unsigned int reg)
+{
+ switch (reg) {
+ case LTC2688_CMD_CH_CODE(0) ... LTC2688_CMD_CH_GAIN(15):
+ return true;
+ case LTC2688_CMD_CONFIG ... LTC2688_CMD_THERMAL_STAT:
+ return true;
+ default:
+ return false;
+ }
+}
+
+static bool ltc2688_reg_writable(struct device *dev, unsigned int reg)
+{
+ if (reg <= LTC2688_CMD_UPDATE_ALL && reg != LTC2688_CMD_THERMAL_STAT)
+ return true;
+
+ return false;
+}
+
+struct regmap_bus ltc2688_regmap_bus = {
+ .read = ltc2688_spi_read,
+ .write = ltc2688_spi_write,
+ .read_flag_mask = LTC2688_READ_OPERATION,
+ .reg_format_endian_default = REGMAP_ENDIAN_BIG,
+ .val_format_endian_default = REGMAP_ENDIAN_BIG
+};
+
+static const struct regmap_config ltc2688_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 16,
+ .readable_reg = ltc2688_reg_readable,
+ .writeable_reg = ltc2688_reg_writable,
+ /* ignoring the no op command */
+ .max_register = LTC2688_CMD_UPDATE_ALL
+};
+
+static const struct iio_info ltc2688_info = {
+ .write_raw = ltc2688_write_raw,
+ .read_raw = ltc2688_read_raw,
+ .read_avail = ltc2688_read_avail,
+ .debugfs_reg_access = ltc2688_reg_access,
+};
+
+static int ltc2688_probe(struct spi_device *spi)
+{
+ struct ltc2688_state *st;
+ struct iio_dev *indio_dev;
+ struct regulator *vref_reg;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ st = iio_priv(indio_dev);
+ st->spi = spi;
+ /* Just this once. No need to di it in every regmap read */
+ st->tx_data[0] = LTC2688_CMD_NOOP;
+ mutex_init(&st->lock);
+
+ st->regmap = devm_regmap_init(&spi->dev, &ltc2688_regmap_bus, st,
+ &ltc2688_regmap_config);
+ if (IS_ERR(st->regmap))
+ return dev_err_probe(&spi->dev, PTR_ERR(st->regmap),
+ "Failed to init regmap");
+
+ st->regulators[0].supply = "vcc";
+ st->regulators[1].supply = "iovcc";
+ ret = devm_regulator_bulk_get(&spi->dev, ARRAY_SIZE(st->regulators),
+ st->regulators);
+ if (ret)
+ return dev_err_probe(&spi->dev, ret, "Failed to get regulators\n");
+
+ ret = regulator_bulk_enable(ARRAY_SIZE(st->regulators), st->regulators);
+ if (ret)
+ return dev_err_probe(&spi->dev, ret,
+ "Failed to enable regulators\n");
+
+ ret = devm_add_action_or_reset(&spi->dev, ltc2688_bulk_disable, st);
+ if (ret)
+ return ret;
+
+ vref_reg = devm_regulator_get_optional(&spi->dev, "vref");
+ if (!IS_ERR(vref_reg)) {
+ ret = regulator_enable(vref_reg);
+ if (ret)
+ return dev_err_probe(&spi->dev, ret,
+ "Failed to enable vref regulators\n");
+
+ ret = devm_add_action_or_reset(&spi->dev,
+ ltc2688_disable_regulator,
+ vref_reg);
+ if (ret)
+ return ret;
+
+ ret = regulator_get_voltage(vref_reg);
+ if (ret < 0)
+ return dev_err_probe(&spi->dev, ret,
+ "Failed to get vref\n");
+
+ st->vref = ret / 1000;
+ } else {
+ if (PTR_ERR(vref_reg) != -ENODEV)
+ return dev_err_probe(&spi->dev, PTR_ERR(vref_reg),
+ "Failed to get vref regulator");
+
+ vref_reg = NULL;
+ /* internal reference */
+ st->vref = 4096;
+ }
+
+ indio_dev->name = "ltc2688";
+ indio_dev->info = &ltc2688_info;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->channels = ltc2688_channels;
+ indio_dev->num_channels = ARRAY_SIZE(ltc2688_channels);
+
+ ret = ltc2688_setup(st, vref_reg);
+ if (ret < 0)
+ return ret;
+
+ return devm_iio_device_register(&st->spi->dev, indio_dev);
+}
+
+static const struct of_device_id ltc2688_of_id[] = {
+ { .compatible = "adi,ltc2688" },
+ {}
+};
+MODULE_DEVICE_TABLE(of, ltc2688_of_id);
+
+static const struct spi_device_id ltc2688_id[] = {
+ { "ltc2688" },
+ {}
+};
+MODULE_DEVICE_TABLE(spi, ltc2688_id);
+
+static struct spi_driver ltc2688_driver = {
+ .driver = {
+ .name = "ltc2688",
+ .of_match_table = ltc2688_of_id,
+ },
+ .probe = ltc2688_probe,
+ .id_table = ltc2688_id,
+};
+module_spi_driver(ltc2688_driver);
+
+MODULE_AUTHOR("Nuno Sá <nuno.sa@analog.com>");
+MODULE_DESCRIPTION("Analog Devices LTC2688 DAC");
+MODULE_LICENSE("GPL");
--
2.17.1