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Message-ID: <20200804100414.39002-1-alexandru.ardelean@analog.com>
Date: Tue, 4 Aug 2020 13:04:13 +0300
From: Alexandru Ardelean <alexandru.ardelean@...log.com>
To: <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>
CC: <jic23@...nel.org>, Stefan Popa <stefan.popa@...log.com>,
"Alexandru Ardelean" <alexandru.ardelean@...log.com>
Subject: [PATCH 1/2] iio: imu: adis16480: Add support for burst read function
From: Stefan Popa <stefan.popa@...log.com>
The burst read function (BRF) provides a method for reading a batch of
data (status, temperature, gyroscopes, accelerometers, timestamp/data
counter and CRC code), which does not require a stall time between each
16-bit sgment and only requires on command on the DIN line to initiate.
The BRF contains either 19 or 20 different data segments of 16-bits
each. After making the burst request, the response can have one or two
"don't care" 16-bit responses before the BURST_ID. This is why the
received burst sequence needs to be followed until the BURST_ID is
detected, which indicates that the data will be contained in the
following 17 segments of 16-bits each. Temperature is the first data
channel in the sequence.
Currently, the burst function is activated by default for all devices
that support it. A future patch will offer the option to enable/disable
this feature from userspace.
Also, the CRC code is not checked. This will be added in a future patch
as well.
Signed-off-by: Stefan Popa <stefan.popa@...log.com>
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
---
drivers/iio/imu/adis16480.c | 106 +++++++++++++++++++++++++++++++++++-
1 file changed, 105 insertions(+), 1 deletion(-)
diff --git a/drivers/iio/imu/adis16480.c b/drivers/iio/imu/adis16480.c
index 1eb4f98076f1..9b100c8fb744 100644
--- a/drivers/iio/imu/adis16480.c
+++ b/drivers/iio/imu/adis16480.c
@@ -23,6 +23,9 @@
#include <linux/iio/buffer.h>
#include <linux/iio/imu/adis.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
+
#include <linux/debugfs.h>
#define ADIS16480_PAGE_SIZE 0x80
@@ -101,6 +104,9 @@
* Available only for ADIS1649x devices
*/
#define ADIS16495_REG_SYNC_SCALE ADIS16480_REG(0x03, 0x10)
+#define ADIS16495_REG_BURST_CMD ADIS16480_REG(0x00, 0x7C)
+#define ADIS16495_BURST_ID 0xA5A5
+#define ADIS16495_BURST_MAX_DATA 20
#define ADIS16480_REG_SERIAL_NUM ADIS16480_REG(0x04, 0x20)
@@ -138,6 +144,7 @@ struct adis16480_chip_info {
unsigned int max_dec_rate;
const unsigned int *filter_freqs;
bool has_pps_clk_mode;
+ struct adis_burst *burst;
const struct adis_data adis_data;
};
@@ -163,6 +170,20 @@ struct adis16480 {
unsigned int clk_freq;
};
+static struct adis_burst adis16495_burst = {
+ .en = true,
+ .reg_cmd = ADIS16495_REG_BURST_CMD,
+ /*
+ * adis_update_scan_mode_burst() sets the burst length in respect with
+ * the number of channels and allocates 16 bits for each. However, for
+ * adis1649x devices, the data for each channel is composed of a 16-bit
+ * low and 16-bit high part. Besides this, the burst sequence contains
+ * data for BURST_ID, SYS_E_FLAG, TIME_STAMP, CRC_LWR, CRC_UPR, one or
+ * two don't care segments.
+ */
+ .extra_len = 12 * sizeof(u16),
+};
+
static const char * const adis16480_int_pin_names[4] = {
[ADIS16480_PIN_DIO1] = "DIO1",
[ADIS16480_PIN_DIO2] = "DIO2",
@@ -953,6 +974,7 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
.max_dec_rate = 4250,
.filter_freqs = adis16495_def_filter_freqs,
.has_pps_clk_mode = true,
+ .burst = &adis16495_burst,
.adis_data = ADIS16480_DATA(16495, &adis16495_1_timeouts),
},
[ADIS16495_2] = {
@@ -967,6 +989,7 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
.max_dec_rate = 4250,
.filter_freqs = adis16495_def_filter_freqs,
.has_pps_clk_mode = true,
+ .burst = &adis16495_burst,
.adis_data = ADIS16480_DATA(16495, &adis16495_1_timeouts),
},
[ADIS16495_3] = {
@@ -981,6 +1004,7 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
.max_dec_rate = 4250,
.filter_freqs = adis16495_def_filter_freqs,
.has_pps_clk_mode = true,
+ .burst = &adis16495_burst,
.adis_data = ADIS16480_DATA(16495, &adis16495_1_timeouts),
},
[ADIS16497_1] = {
@@ -995,6 +1019,7 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
.max_dec_rate = 4250,
.filter_freqs = adis16495_def_filter_freqs,
.has_pps_clk_mode = true,
+ .burst = &adis16495_burst,
.adis_data = ADIS16480_DATA(16497, &adis16495_1_timeouts),
},
[ADIS16497_2] = {
@@ -1009,6 +1034,7 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
.max_dec_rate = 4250,
.filter_freqs = adis16495_def_filter_freqs,
.has_pps_clk_mode = true,
+ .burst = &adis16495_burst,
.adis_data = ADIS16480_DATA(16497, &adis16495_1_timeouts),
},
[ADIS16497_3] = {
@@ -1023,10 +1049,81 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
.max_dec_rate = 4250,
.filter_freqs = adis16495_def_filter_freqs,
.has_pps_clk_mode = true,
+ .burst = &adis16495_burst,
.adis_data = ADIS16480_DATA(16497, &adis16495_1_timeouts),
},
};
+static irqreturn_t adis16480_trigger_handler(int irq, void *p)
+{
+ struct iio_poll_func *pf = p;
+ struct iio_dev *indio_dev = pf->indio_dev;
+ struct adis16480 *st = iio_priv(indio_dev);
+ struct adis *adis = &st->adis;
+ int ret, bit, offset, i = 0;
+ __be16 data[ADIS16495_BURST_MAX_DATA], *buffer, *d;
+
+ if (!adis->buffer)
+ return -ENOMEM;
+
+ mutex_lock(&adis->state_lock);
+ if (adis->current_page != 0) {
+ adis->tx[0] = ADIS_WRITE_REG(ADIS_REG_PAGE_ID);
+ adis->tx[1] = 0;
+ spi_write(adis->spi, adis->tx, 2);
+ }
+
+ ret = spi_sync(adis->spi, &adis->msg);
+ if (ret)
+ dev_err(&adis->spi->dev, "Failed to read data: %d\n", ret);
+
+ adis->current_page = 0;
+ mutex_unlock(&adis->state_lock);
+
+ if (!(adis->burst && adis->burst->en)) {
+ buffer = adis->buffer;
+ goto push_to_buffers;
+ }
+ /*
+ * After making the burst request, the response can have one or two
+ * "don't care" 16-bit responses, before the BURST_ID.
+ */
+ d = (__be16 *)adis->buffer;
+ for (offset = 0; offset < 3; offset++) {
+ if (d[offset] == ADIS16495_BURST_ID) {
+ offset += 2; /* TEMP_OUT */
+ break;
+ }
+ }
+
+ for_each_set_bit(bit, indio_dev->active_scan_mask,
+ indio_dev->masklength) {
+ /*
+ * When burst mode is used, temperature is the first data
+ * channel in the sequence, but the temperature scan index
+ * is 10.
+ */
+ if (bit == ADIS16480_SCAN_TEMP) {
+ data[2 * i] = d[offset];
+ } else {
+ /* The lower register data is sequenced first */
+ data[2 * i] = d[2 * bit + offset + 2];
+ data[2 * i + 1] = d[2 * bit + offset + 1];
+ }
+ i++;
+ }
+
+ buffer = data;
+
+push_to_buffers:
+ iio_push_to_buffers_with_timestamp(indio_dev, buffer,
+ pf->timestamp);
+
+ iio_trigger_notify_done(indio_dev->trig);
+
+ return IRQ_HANDLED;
+}
+
static const struct iio_info adis16480_info = {
.read_raw = &adis16480_read_raw,
.write_raw = &adis16480_write_raw,
@@ -1264,7 +1361,14 @@ static int adis16480_probe(struct spi_device *spi)
st->clk_freq = st->chip_info->int_clk;
}
- ret = adis_setup_buffer_and_trigger(&st->adis, indio_dev, NULL);
+ /* If burst mode is supported, enable it by default */
+ if (st->chip_info->burst) {
+ st->adis.burst = st->chip_info->burst;
+ st->adis.burst_extra_len = st->chip_info->burst->extra_len;
+ }
+
+ ret = adis_setup_buffer_and_trigger(&st->adis, indio_dev,
+ adis16480_trigger_handler);
if (ret)
goto error_clk_disable_unprepare;
--
2.17.1
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