Hi Shubhrajyoti, On 02/15/2011 12:47 PM, Shubhrajyoti wrote: > Hi Michael, > >> +static IIO_DEV_ATTR_IN_RAW(6, ad7298_scan, 6); >> +static IIO_DEV_ATTR_IN_RAW(7, ad7298_scan, 7); >> + >> +static ssize_t ad7298_show_temp(struct device *dev, >> + struct device_attribute *attr, >> + char *buf) >> +{ >> + /* Driver currently only support internal vref */ >> + struct iio_dev *dev_info = dev_get_drvdata(dev); >> + struct ad7298_state *st = iio_dev_get_devdata(dev_info); >> + unsigned short tmp; >> + char sign; >> + >> + tmp = cpu_to_be16(AD7298_WRITE | AD7298_TSENSE | >> + AD7298_TAVG | st->ext_ref); >> > didnt understand why you needed the cpu_to_be16 here? > The AD7298, like almost any SPI slave device, uses MSB first. tmp is type unsigned short. SPI uses 8-bit transfers by default. The pointer to tmp is handed to spi_write. So on a little endian machine it would transfer the low byte instead of high byte first. cpu_to_be16() flips the byte order on LE and does nothing on BE. >> + >> + spi_write(st->spi, (u8 *)&tmp, 2); >> + tmp = 0; >> + spi_write(st->spi, (u8 *)&tmp, 2); >> + usleep_range(101, 1000); /* sleep> 100us */ >> + spi_read(st->spi, (u8 *)&tmp, 2); >> + >> + tmp = be16_to_cpu(tmp)& RES_MASK(AD7298_BITS); >> + >> + /* >> + * One LSB of the ADC corresponds to 0.25 deg C. >> + * The temperature reading is in 12-bit twos complement format >> + */ >> + >> + if (tmp& (1<< (AD7298_BITS - 1))) { >> + tmp = (1<< AD7298_BITS) - tmp; >> + sign = '-'; >> + } else { >> + sign = '+'; >> + } >> + >> + return sprintf(buf, "%c%d.%.2d\n", sign, tmp / 4, (tmp& 3) * 25); >> +} >> + >> +static IIO_DEVICE_ATTR(temp, S_IRUGO, ad7298_show_temp, NULL, 0); >> >> > <snip> > >> + >> +static int ad7298_remove(struct spi_device *spi) >> > May consider __devexit > Good catch. >> +{ >> + struct ad7298_state *st = spi_get_drvdata(spi); >> + struct iio_dev *indio_dev = st->indio_dev; >> + >> + iio_ring_buffer_unregister(indio_dev->ring); >> + ad7298_ring_cleanup(indio_dev); >> + iio_device_unregister(indio_dev); >> + if (!IS_ERR(st->reg)) { >> + regulator_disable(st->reg); >> + regulator_put(st->reg); >> + } >> + kfree(st); >> + return 0; >> +} >> + >> +static const struct spi_device_id ad7298_id[] = { >> + {"ad7298", 0}, >> + {} >> +}; >> + >> +static struct spi_driver ad7298_driver = { >> + .driver = { >> + .name = "ad7298", >> + .bus =&spi_bus_type, >> + .owner = THIS_MODULE, >> + }, >> + .probe = ad7298_probe, >> + .remove = __devexit_p(ad7298_remove), >> + .id_table = ad7298_id, >> +}; >> + >> +static int __init ad7298_init(void) >> +{ >> + return spi_register_driver(&ad7298_driver); >> +} >> +module_init(ad7298_init); >> + >> +static void __exit ad7298_exit(void) >> +{ >> + spi_unregister_driver(&ad7298_driver); >> +} >> > <snip> > >> + ret = -ENOMEM; >> + goto error_ret; >> + } >> + ret = ring->access.read_last(ring, (u8 *) ring_data); >> + if (ret) >> + goto error_free_ring_data; >> + >> + ret = be16_to_cpu(ring_data[ch]); >> + >> +error_free_ring_data: >> + kfree(ring_data); >> +error_ret: >> + return ret; >> +} >> + >> +/** >> + * ad7298_ring_preenable() setup the parameters of the ring before enabling >> + * >> + * The complex nature of the setting of the nuber of bytes per datum is due >> > typo number. > Thanks >> + * to this driver currently ensuring that the timestamp is stored at an 8 >> + * byte boundary. >> + **/ >> +static int ad7298_ring_preenable(struct iio_dev *indio_dev) >> +{ >> + struct ad7298_state *st = indio_dev->dev_data; >> + struct iio_ring_buffer *ring = indio_dev->ring; >> + size_t d_size; >> + int i, m; >> + unsigned short command; >> + >> + d_size = ring->scan_count * >> + (AD7298_STORAGE_BITS / 8) + sizeof(s64); >> + >> + if (d_size % sizeof(s64)) >> + d_size += sizeof(s64) - (d_size % sizeof(s64)); >> + >> + if (ring->access.set_bytes_per_datum) >> + ring->access.set_bytes_per_datum(ring, d_size); >> + >> + st->d_size = d_size; >> + >> + command = AD7298_WRITE | st->ext_ref; >> + >> + for (i = 0, m = AD7298_CH0; i< AD7298_MAX_CHAN; i++, m>>= 1) >> + if (ring->scan_mask& (1<< i)) >> + command |= m; >> + >> + st->tx_buf[0] = cpu_to_be16(command); >> + >> + /* build spi ring message */ >> + st->ring_xfer[0].tx_buf =&st->tx_buf[0]; >> + st->ring_xfer[0].len = 2; >> + st->ring_xfer[0].cs_change = 1; >> + st->ring_xfer[1].tx_buf =&st->tx_buf[1]; >> + st->ring_xfer[1].len = 2; >> + st->ring_xfer[1].cs_change = 1; >> + >> + spi_message_init(&st->ring_msg); >> + spi_message_add_tail(&st->ring_xfer[0],&st->ring_msg); >> + spi_message_add_tail(&st->ring_xfer[1],&st->ring_msg); >> + >> + for (i = 0; i< ring->scan_count; i++) { >> + st->ring_xfer[i + 2].rx_buf =&st->rx_buf[i]; >> + st->ring_xfer[i + 2].len = 2; >> + st->ring_xfer[i + 2].cs_change = 1; >> + spi_message_add_tail(&st->ring_xfer[i + 2],&st->ring_msg); >> + } >> + /* make sure last transfer cs_change is not set */ >> + st->ring_xfer[i + 1].cs_change = 0; >> + >> + return 0; >> +} >> + >> +/** >> + * ad7298_poll_func_th() th of trigger launched polling to ring buffer >> + * >> + * As sampling only occurs on spi comms occuring, leave timestamping until >> + * then. Some triggers will generate their own time stamp. Currently >> + * there is no way of notifying them when no one cares. >> + **/ >> +static void ad7298_poll_func_th(struct iio_dev *indio_dev, s64 time) >> +{ >> + struct ad7298_state *st = indio_dev->dev_data; >> + >> + schedule_work(&st->poll_work); >> + return; >> +} >> +/** >> + * ad7298_poll_bh_to_ring() bh of trigger launched polling to ring buffer >> + * @work_s: the work struct through which this was scheduled >> + * >> + * Currently there is no option in this driver to disable the saving of >> + * timestamps within the ring. >> + * I think the one copy of this at a time was to avoid problems if the >> + * trigger was set far too high and the reads then locked up the computer. >> + **/ >> +static void ad7298_poll_bh_to_ring(struct work_struct *work_s) >> +{ >> + struct ad7298_state *st = container_of(work_s, struct ad7298_state, >> + poll_work); >> + struct iio_dev *indio_dev = st->indio_dev; >> + struct iio_sw_ring_buffer *sw_ring = iio_to_sw_ring(indio_dev->ring); >> + struct iio_ring_buffer *ring = indio_dev->ring; >> + s64 time_ns; >> + __u16 buf[16]; >> > Any reason for using __u16 > No >> + int b_sent, i; >> + >> + /* Ensure only one copy of this function running at a time */ >> + if (atomic_inc_return(&st->protect_ring)> 1) >> + return; >> + >> + b_sent = spi_sync(st->spi,&st->ring_msg); >> > -- Greetings, Michael -- Analog Devices GmbH Wilhelm-Wagenfeld-Str. 6 80807 Muenchen Sitz der Gesellschaft: Muenchen; Registergericht: Muenchen HRB 40368; Geschaeftsfuehrer:Dr.Carsten Suckrow, Thomas Wessel, William A. 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