From: Stefan Popa <stefan.popa@xxxxxxxxxx> 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@xxxxxxxxxx> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx> --- 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