On 11/20/2016 12:28 PM, David Lechner wrote:
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@xxxxxxxxxxxxxx>
---
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 | 488 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 502 insertions(+)
create mode 100644 drivers/iio/adc/ti-ads7950.c
...
diff --git a/drivers/iio/adc/ti-ads7950.c b/drivers/iio/adc/ti-ads7950.c
new file mode 100644
index 0000000..d0b76bd
--- /dev/null
+++ b/drivers/iio/adc/ti-ads7950.c
...
+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 b_sent;
+
+ b_sent = spi_sync(st->spi, &st->ring_msg);
hmm, I copied this from another driver, but spi_sync() in IRQ handler
does not sound like a good idea (spi_sync() can sleep). I will replace
it with spi_async().
+ if (b_sent)
+ goto done;
+
+ iio_push_to_buffers_with_timestamp(indio_dev, st->rx_buf,
+ iio_get_time_ns(indio_dev));
+
+done:
+ iio_trigger_notify_done(indio_dev->trig);
+
+ return IRQ_HANDLED;
+}
...
+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, 0, 12);
I'm not sure if I am doing this right. There are 8- 10- and 12-bit
versions of this chip. The 8- and 10-bit versions still return a 12-bit
number where the last 4 or 2 bits are always 0. Should I be shifting the
12-bit value here based on the chip being used so that *val is 0-255 for
8-bit and 0-1023 for 10-bit? Or should this be *really* raw and not even
use TI_ADS7950_EXTRACT() to mask the channel address bits?
+
+ return IIO_VAL_INT;
+ case IIO_CHAN_INFO_SCALE:
+ ret = ti_ads7950_get_range(st);
+ if (ret < 0)
+ return ret;
+
+ *val = ret;
+ *val2 = chan->scan_type.realbits;
+
+ return IIO_VAL_FRACTIONAL_LOG2;
+ }
+
+ return -EINVAL;
+}
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