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Subject[PATCH v4] iio: adc: New driver for TI ADS7950 chips
Date
This adds a new driver for the TI ADS7950 family of ADC chips. These
communicate using SPI and come in 8/10/12-bit and 4/8/12/16 channel
varieties.

Signed-off-by: David Lechner <david@lechnology.com>
---

v4 changes:
* Change spi_async() back to spi_sync(). (I have learned that this is in a
threaded interrupt handler, so sleeping is OK.)

v3 changes:

* Use spi_async() instead of spi_sync() in ti_ads7950_trigger_handler()
* Fix scaling in ti_ads7950_read_raw()

v2 changes:

* Got rid of XX wildcards - using ADS7950 everywhere
* Fixed some macro parentheses issues
* Added TI_ prefix to macros to match ti_ prefixes used elsewhere
* Added space in rx_buf for holding timestamp
* Use iio_device_claim_direct_mode() and spi_message_init_with_transfers()
helper functions
* Don't use dev_info() at end of probe
* Minor spelling and code style fixes

drivers/iio/adc/Kconfig | 13 ++
drivers/iio/adc/Makefile | 1 +
drivers/iio/adc/ti-ads7950.c | 490 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 504 insertions(+)
create mode 100644 drivers/iio/adc/ti-ads7950.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 6bbee0b..26b32f0 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -527,6 +527,19 @@ config TI_ADS1015
This driver can also be built as a module. If so, the module will be
called ti-ads1015.

+config TI_ADS7950
+ tristate "Texas Instruments ADS7950 ADC driver"
+ depends on SPI
+ select IIO_BUFFER
+ select IIO_TRIGGERED_BUFFER
+ help
+ Say yes here to build support for Texas Instruments ADS7950, ADS7951,
+ ADS7952, ADS7953, ADS7954, ADS7955, ADS7956, ADS7957, ADS7958, ADS7959.
+ ADS7960, ADS7961.
+
+ To compile this driver as a module, choose M here: the
+ module will be called ti-ads7950.
+
config TI_ADS8688
tristate "Texas Instruments ADS8688"
depends on SPI && OF
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index 9391217..1966801 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -49,6 +49,7 @@ obj-$(CONFIG_TI_ADC12138) += ti-adc12138.o
obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
obj-$(CONFIG_TI_ADC161S626) += ti-adc161s626.o
obj-$(CONFIG_TI_ADS1015) += ti-ads1015.o
+obj-$(CONFIG_TI_ADS7950) += ti-ads7950.o
obj-$(CONFIG_TI_ADS8688) += ti-ads8688.o
obj-$(CONFIG_TI_AM335X_ADC) += ti_am335x_adc.o
obj-$(CONFIG_TWL4030_MADC) += twl4030-madc.o
diff --git a/drivers/iio/adc/ti-ads7950.c b/drivers/iio/adc/ti-ads7950.c
new file mode 100644
index 0000000..0330361
--- /dev/null
+++ b/drivers/iio/adc/ti-ads7950.c
@@ -0,0 +1,490 @@
+/*
+ * Texas Instruments ADS7950 SPI ADC driver
+ *
+ * Copyright 2016 David Lechner <david@lechnology.com>
+ *
+ * Based on iio/ad7923.c:
+ * Copyright 2011 Analog Devices Inc
+ * Copyright 2012 CS Systemes d'Information
+ *
+ * And also on hwmon/ads79xx.c
+ * Copyright (C) 2013 Texas Instruments Incorporated - http://www.ti.com/
+ * Nishanth Menon
+ *
+ * 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 version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/bitops.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/regulator/consumer.h>
+#include <linux/slab.h>
+#include <linux/spi/spi.h>
+
+#include <linux/iio/buffer.h>
+#include <linux/iio/iio.h>
+#include <linux/iio/sysfs.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
+
+#define TI_ADS7950_CR_MANUAL BIT(12)
+#define TI_ADS7950_CR_WRITE BIT(11)
+#define TI_ADS7950_CR_CHAN(ch) ((ch) << 7)
+#define TI_ADS7950_CR_RANGE_5V BIT(6)
+
+#define TI_ADS7950_MAX_CHAN 16
+
+#define TI_ADS7950_TIMESTAMP_SIZE (sizeof(int64_t) / sizeof(__be16))
+
+/* val = value, dec = left shift, bits = number of bits of the mask */
+#define TI_ADS7950_EXTRACT(val, dec, bits) \
+ (((val) >> (dec)) & ((1 << (bits)) - 1))
+
+struct ti_ads7950_state {
+ struct spi_device *spi;
+ struct spi_transfer ring_xfer[TI_ADS7950_MAX_CHAN + 2];
+ struct spi_transfer scan_single_xfer[3];
+ struct spi_message ring_msg;
+ struct spi_message scan_single_msg;
+
+ struct regulator *reg;
+
+ unsigned int settings;
+
+ /*
+ * DMA (thus cache coherency maintenance) requires the
+ * transfer buffers to live in their own cache lines.
+ */
+ __be16 rx_buf[TI_ADS7950_MAX_CHAN + TI_ADS7950_TIMESTAMP_SIZE]
+ ____cacheline_aligned;
+ __be16 tx_buf[TI_ADS7950_MAX_CHAN];
+};
+
+struct ti_ads7950_chip_info {
+ const struct iio_chan_spec *channels;
+ unsigned int num_channels;
+};
+
+enum ti_ads7950_id {
+ TI_ADS7950,
+ TI_ADS7951,
+ TI_ADS7952,
+ TI_ADS7953,
+ TI_ADS7954,
+ TI_ADS7955,
+ TI_ADS7956,
+ TI_ADS7957,
+ TI_ADS7958,
+ TI_ADS7959,
+ TI_ADS7960,
+ TI_ADS7961,
+};
+
+#define TI_ADS7950_V_CHAN(index, bits) \
+{ \
+ .type = IIO_VOLTAGE, \
+ .indexed = 1, \
+ .channel = index, \
+ .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
+ .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
+ .address = index, \
+ .datasheet_name = "CH##index", \
+ .scan_index = index, \
+ .scan_type = { \
+ .sign = 'u', \
+ .realbits = bits, \
+ .storagebits = 16, \
+ .shift = 12 - (bits), \
+ .endianness = IIO_BE, \
+ }, \
+}
+
+#define DECLARE_TI_ADS7950_4_CHANNELS(name, bits) \
+const struct iio_chan_spec name ## _channels[] = { \
+ TI_ADS7950_V_CHAN(0, bits), \
+ TI_ADS7950_V_CHAN(1, bits), \
+ TI_ADS7950_V_CHAN(2, bits), \
+ TI_ADS7950_V_CHAN(3, bits), \
+ IIO_CHAN_SOFT_TIMESTAMP(4), \
+}
+
+#define DECLARE_TI_ADS7950_8_CHANNELS(name, bits) \
+const struct iio_chan_spec name ## _channels[] = { \
+ TI_ADS7950_V_CHAN(0, bits), \
+ TI_ADS7950_V_CHAN(1, bits), \
+ TI_ADS7950_V_CHAN(2, bits), \
+ TI_ADS7950_V_CHAN(3, bits), \
+ TI_ADS7950_V_CHAN(4, bits), \
+ TI_ADS7950_V_CHAN(5, bits), \
+ TI_ADS7950_V_CHAN(6, bits), \
+ TI_ADS7950_V_CHAN(7, bits), \
+ IIO_CHAN_SOFT_TIMESTAMP(8), \
+}
+
+#define DECLARE_TI_ADS7950_12_CHANNELS(name, bits) \
+const struct iio_chan_spec name ## _channels[] = { \
+ TI_ADS7950_V_CHAN(0, bits), \
+ TI_ADS7950_V_CHAN(1, bits), \
+ TI_ADS7950_V_CHAN(2, bits), \
+ TI_ADS7950_V_CHAN(3, bits), \
+ TI_ADS7950_V_CHAN(4, bits), \
+ TI_ADS7950_V_CHAN(5, bits), \
+ TI_ADS7950_V_CHAN(6, bits), \
+ TI_ADS7950_V_CHAN(7, bits), \
+ TI_ADS7950_V_CHAN(8, bits), \
+ TI_ADS7950_V_CHAN(9, bits), \
+ TI_ADS7950_V_CHAN(10, bits), \
+ TI_ADS7950_V_CHAN(11, bits), \
+ IIO_CHAN_SOFT_TIMESTAMP(12), \
+}
+
+#define DECLARE_TI_ADS7950_16_CHANNELS(name, bits) \
+const struct iio_chan_spec name ## _channels[] = { \
+ TI_ADS7950_V_CHAN(0, bits), \
+ TI_ADS7950_V_CHAN(1, bits), \
+ TI_ADS7950_V_CHAN(2, bits), \
+ TI_ADS7950_V_CHAN(3, bits), \
+ TI_ADS7950_V_CHAN(4, bits), \
+ TI_ADS7950_V_CHAN(5, bits), \
+ TI_ADS7950_V_CHAN(6, bits), \
+ TI_ADS7950_V_CHAN(7, bits), \
+ TI_ADS7950_V_CHAN(8, bits), \
+ TI_ADS7950_V_CHAN(9, bits), \
+ TI_ADS7950_V_CHAN(10, bits), \
+ TI_ADS7950_V_CHAN(11, bits), \
+ TI_ADS7950_V_CHAN(12, bits), \
+ TI_ADS7950_V_CHAN(13, bits), \
+ TI_ADS7950_V_CHAN(14, bits), \
+ TI_ADS7950_V_CHAN(15, bits), \
+ IIO_CHAN_SOFT_TIMESTAMP(16), \
+}
+
+static DECLARE_TI_ADS7950_4_CHANNELS(ti_ads7950, 12);
+static DECLARE_TI_ADS7950_8_CHANNELS(ti_ads7951, 12);
+static DECLARE_TI_ADS7950_12_CHANNELS(ti_ads7952, 12);
+static DECLARE_TI_ADS7950_16_CHANNELS(ti_ads7953, 12);
+static DECLARE_TI_ADS7950_4_CHANNELS(ti_ads7954, 10);
+static DECLARE_TI_ADS7950_8_CHANNELS(ti_ads7955, 10);
+static DECLARE_TI_ADS7950_12_CHANNELS(ti_ads7956, 10);
+static DECLARE_TI_ADS7950_16_CHANNELS(ti_ads7957, 10);
+static DECLARE_TI_ADS7950_4_CHANNELS(ti_ads7958, 8);
+static DECLARE_TI_ADS7950_8_CHANNELS(ti_ads7959, 8);
+static DECLARE_TI_ADS7950_12_CHANNELS(ti_ads7960, 8);
+static DECLARE_TI_ADS7950_16_CHANNELS(ti_ads7961, 8);
+
+static const struct ti_ads7950_chip_info ti_ads7950_chip_info[] = {
+ [TI_ADS7950] = {
+ .channels = ti_ads7950_channels,
+ .num_channels = ARRAY_SIZE(ti_ads7950_channels),
+ },
+ [TI_ADS7951] = {
+ .channels = ti_ads7951_channels,
+ .num_channels = ARRAY_SIZE(ti_ads7951_channels),
+ },
+ [TI_ADS7952] = {
+ .channels = ti_ads7952_channels,
+ .num_channels = ARRAY_SIZE(ti_ads7952_channels),
+ },
+ [TI_ADS7953] = {
+ .channels = ti_ads7953_channels,
+ .num_channels = ARRAY_SIZE(ti_ads7953_channels),
+ },
+ [TI_ADS7954] = {
+ .channels = ti_ads7954_channels,
+ .num_channels = ARRAY_SIZE(ti_ads7954_channels),
+ },
+ [TI_ADS7955] = {
+ .channels = ti_ads7955_channels,
+ .num_channels = ARRAY_SIZE(ti_ads7955_channels),
+ },
+ [TI_ADS7956] = {
+ .channels = ti_ads7956_channels,
+ .num_channels = ARRAY_SIZE(ti_ads7956_channels),
+ },
+ [TI_ADS7957] = {
+ .channels = ti_ads7957_channels,
+ .num_channels = ARRAY_SIZE(ti_ads7957_channels),
+ },
+ [TI_ADS7958] = {
+ .channels = ti_ads7958_channels,
+ .num_channels = ARRAY_SIZE(ti_ads7958_channels),
+ },
+ [TI_ADS7959] = {
+ .channels = ti_ads7959_channels,
+ .num_channels = ARRAY_SIZE(ti_ads7959_channels),
+ },
+ [TI_ADS7960] = {
+ .channels = ti_ads7960_channels,
+ .num_channels = ARRAY_SIZE(ti_ads7960_channels),
+ },
+ [TI_ADS7961] = {
+ .channels = ti_ads7961_channels,
+ .num_channels = ARRAY_SIZE(ti_ads7961_channels),
+ },
+};
+
+/*
+ * ti_ads7950_update_scan_mode() setup the spi transfer buffer for the new
+ * scan mask
+ */
+static int ti_ads7950_update_scan_mode(struct iio_dev *indio_dev,
+ const unsigned long *active_scan_mask)
+{
+ struct ti_ads7950_state *st = iio_priv(indio_dev);
+ int i, cmd, len;
+
+ len = 0;
+ for_each_set_bit(i, active_scan_mask, indio_dev->num_channels) {
+ cmd = TI_ADS7950_CR_WRITE | TI_ADS7950_CR_CHAN(i) | st->settings;
+ st->tx_buf[len++] = cpu_to_be16(cmd);
+ }
+
+ /* Data for the 1st channel is not returned until the 3rd transfer */
+ len += 2;
+ for (i = 0; i < len; i++) {
+ if ((i + 2) < len)
+ st->ring_xfer[i].tx_buf = &st->tx_buf[i];
+ if (i >= 2)
+ st->ring_xfer[i].rx_buf = &st->rx_buf[i - 2];
+ st->ring_xfer[i].len = 2;
+ st->ring_xfer[i].cs_change = 1;
+ }
+ /* make sure last transfer's cs_change is not set */
+ st->ring_xfer[len - 1].cs_change = 0;
+
+ spi_message_init_with_transfers(&st->ring_msg, st->ring_xfer, len);
+
+ return 0;
+}
+
+static irqreturn_t ti_ads7950_trigger_handler(int irq, void *p)
+{
+ struct iio_poll_func *pf = p;
+ struct iio_dev *indio_dev = pf->indio_dev;
+ struct ti_ads7950_state *st = iio_priv(indio_dev);
+ int ret;
+
+ ret = spi_sync(st->spi, &st->ring_msg);
+ if (ret < 0)
+ goto out;
+
+ iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
+ iio_get_time_ns(indio_dev));
+
+out:
+ iio_trigger_notify_done(indio_dev->trig);
+
+ return IRQ_HANDLED;
+}
+
+static int ti_ads7950_scan_direct(struct ti_ads7950_state *st, unsigned int ch)
+{
+ int ret, cmd;
+
+ cmd = TI_ADS7950_CR_WRITE | TI_ADS7950_CR_CHAN(ch) | st->settings;
+ st->tx_buf[0] = cpu_to_be16(cmd);
+
+ ret = spi_sync(st->spi, &st->scan_single_msg);
+ if (ret)
+ return ret;
+
+ return be16_to_cpu(st->rx_buf[0]);
+}
+
+static int ti_ads7950_get_range(struct ti_ads7950_state *st)
+{
+ int vref;
+
+ vref = regulator_get_voltage(st->reg);
+ if (vref < 0)
+ return vref;
+
+ vref /= 1000;
+
+ if (st->settings & TI_ADS7950_CR_RANGE_5V)
+ vref *= 2;
+
+ return vref;
+}
+
+static int ti_ads7950_read_raw(struct iio_dev *indio_dev,
+ struct iio_chan_spec const *chan,
+ int *val, int *val2, long m)
+{
+ struct ti_ads7950_state *st = iio_priv(indio_dev);
+ int ret;
+
+ switch (m) {
+ case IIO_CHAN_INFO_RAW:
+
+ ret = iio_device_claim_direct_mode(indio_dev);
+ if (ret < 0)
+ return ret;
+
+ ret = ti_ads7950_scan_direct(st, chan->address);
+ iio_device_release_direct_mode(indio_dev);
+ if (ret < 0)
+ return ret;
+
+ if (chan->address != TI_ADS7950_EXTRACT(ret, 12, 4))
+ return -EIO;
+
+ *val = TI_ADS7950_EXTRACT(ret, chan->scan_type.shift,
+ chan->scan_type.realbits);
+
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_SCALE:
+ ret = ti_ads7950_get_range(st);
+ if (ret < 0)
+ return ret;
+
+ *val = ret;
+ *val2 = (1 << chan->scan_type.realbits) - 1;
+
+ return IIO_VAL_FRACTIONAL;
+ }
+
+ return -EINVAL;
+}
+
+static const struct iio_info ti_ads7950_info = {
+ .read_raw = &ti_ads7950_read_raw,
+ .update_scan_mode = ti_ads7950_update_scan_mode,
+ .driver_module = THIS_MODULE,
+};
+
+static int ti_ads7950_probe(struct spi_device *spi)
+{
+ struct ti_ads7950_state *st;
+ struct iio_dev *indio_dev;
+ const struct ti_ads7950_chip_info *info;
+ int ret;
+
+ indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
+ if (!indio_dev)
+ return -ENOMEM;
+
+ st = iio_priv(indio_dev);
+
+ spi_set_drvdata(spi, indio_dev);
+
+ st->spi = spi;
+ st->settings = TI_ADS7950_CR_MANUAL | TI_ADS7950_CR_RANGE_5V;
+
+ info = &ti_ads7950_chip_info[spi_get_device_id(spi)->driver_data];
+
+ indio_dev->name = spi_get_device_id(spi)->name;
+ indio_dev->dev.parent = &spi->dev;
+ indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->channels = info->channels;
+ indio_dev->num_channels = info->num_channels;
+ indio_dev->info = &ti_ads7950_info;
+
+ /*
+ * Setup default message. The sample is read at the end of the first
+ * transfer, then it takes one full cycle to convert the sample and one
+ * more cycle to send the value. The conversion process is driven by
+ * the SPI clock, which is why we have 3 transfers. The middle one is
+ * just dummy data sent while the chip is converting the sample that
+ * was read at the end of the first transfer.
+ */
+
+ st->scan_single_xfer[0].tx_buf = &st->tx_buf[0];
+ st->scan_single_xfer[0].len = 2;
+ st->scan_single_xfer[0].cs_change = 1;
+ st->scan_single_xfer[1].tx_buf = &st->tx_buf[0];
+ st->scan_single_xfer[1].len = 2;
+ st->scan_single_xfer[1].cs_change = 1;
+ st->scan_single_xfer[2].rx_buf = &st->rx_buf[0];
+ st->scan_single_xfer[2].len = 2;
+
+ spi_message_init_with_transfers(&st->scan_single_msg,
+ st->scan_single_xfer, 3);
+
+ st->reg = devm_regulator_get(&spi->dev, "refin");
+ if (IS_ERR(st->reg)) {
+ dev_err(&spi->dev, "Failed get get regulator \"refin\"\n");
+ return PTR_ERR(st->reg);
+ }
+
+ ret = regulator_enable(st->reg);
+ if (ret) {
+ dev_err(&spi->dev, "Failed to enable regulator \"refin\"\n");
+ return ret;
+ }
+
+ ret = iio_triggered_buffer_setup(indio_dev, NULL,
+ &ti_ads7950_trigger_handler, NULL);
+ if (ret) {
+ dev_err(&spi->dev, "Failed to setup triggered buffer\n");
+ goto error_disable_reg;
+ }
+
+ ret = iio_device_register(indio_dev);
+ if (ret) {
+ dev_err(&spi->dev, "Failed to register iio device\n");
+ goto error_cleanup_ring;
+ }
+
+ return 0;
+
+error_cleanup_ring:
+ iio_triggered_buffer_cleanup(indio_dev);
+error_disable_reg:
+ regulator_disable(st->reg);
+
+ return ret;
+}
+
+static int ti_ads7950_remove(struct spi_device *spi)
+{
+ struct iio_dev *indio_dev = spi_get_drvdata(spi);
+ struct ti_ads7950_state *st = iio_priv(indio_dev);
+
+ iio_device_unregister(indio_dev);
+ iio_triggered_buffer_cleanup(indio_dev);
+ regulator_disable(st->reg);
+
+ return 0;
+}
+
+static const struct spi_device_id ti_ads7950_id[] = {
+ {"ti-ads7950", TI_ADS7950},
+ {"ti-ads7951", TI_ADS7951},
+ {"ti-ads7952", TI_ADS7952},
+ {"ti-ads7953", TI_ADS7953},
+ {"ti-ads7954", TI_ADS7954},
+ {"ti-ads7955", TI_ADS7955},
+ {"ti-ads7956", TI_ADS7956},
+ {"ti-ads7957", TI_ADS7957},
+ {"ti-ads7958", TI_ADS7958},
+ {"ti-ads7959", TI_ADS7959},
+ {"ti-ads7960", TI_ADS7960},
+ {"ti-ads7961", TI_ADS7961},
+ { }
+};
+MODULE_DEVICE_TABLE(spi, ti_ads7950_id);
+
+static struct spi_driver ti_ads7950_driver = {
+ .driver = {
+ .name = "ti-ads7950",
+ },
+ .probe = ti_ads7950_probe,
+ .remove = ti_ads7950_remove,
+ .id_table = ti_ads7950_id,
+};
+module_spi_driver(ti_ads7950_driver);
+
+MODULE_AUTHOR("David Lechner <david@lechnology.com>");
+MODULE_DESCRIPTION("TI TI_ADS7950 ADC");
+MODULE_LICENSE("GPL v2");
--
2.7.4
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