From: Jonathan Cameron <jic23@kernel.org>
To: Nuno Sa <nuno.sa@analog.com>
Cc: <linux-iio@vger.kernel.org>,
Michael Hennerich <Michael.Hennerich@analog.com>,
Lars-Peter Clausen <lars@metafoo.de>
Subject: Re: [PATCH v2] iio: adis16480: support burst read function
Date: Sun, 11 Apr 2021 15:40:02 +0100 [thread overview]
Message-ID: <20210411154002.159c4018@jic23-huawei> (raw)
In-Reply-To: <20210408075643.70183-1-nuno.sa@analog.com>
On Thu, 8 Apr 2021 09:56:43 +0200
Nuno Sa <nuno.sa@analog.com> wrote:
> Some supported devices support burst read function. This provides a method
> for reading a batch of data (status, temperature, gyroscopes,
> accelerometers, time stamp/data counter, and CRC code), which does not
> require a stall time between each 16-bit segment and only requires one
> command on the DIN line to initiate. Devices supporting this mode
> are:
>
> * adis16495-1
> * adis16495-2
> * adis16495-3
> * adis16497-1
> * adis16497-2
> * adis16497-3
>
> Signed-off-by: Nuno Sa <nuno.sa@analog.com>
Small issue with return values in the trigger handler and
some stylistic comments.
Otherwise, looks good to me.
> ---
> Changes in v2:
> * Return right away if offset == 4 (no valid transition found from
> brurst_id to sys_flags)
>
> drivers/iio/imu/adis16480.c | 161 +++++++++++++++++++++++++++++++++---
> 1 file changed, 148 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/iio/imu/adis16480.c b/drivers/iio/imu/adis16480.c
> index f81b86690b76..b782070a27f5 100644
> --- a/drivers/iio/imu/adis16480.c
> +++ b/drivers/iio/imu/adis16480.c
> @@ -5,6 +5,7 @@
> * Copyright 2012 Analog Devices Inc.
> */
>
> +#include <linux/crc32.h>
Hmm. The ordering here is a bit odd so I guess this doesn't
really matter, but seems strange to have something so specific as
crc32.h as the first header included when it's not the first one
alphabetically.
> #include <linux/clk.h>
> #include <linux/bitfield.h>
> #include <linux/of_irq.h>
> @@ -19,11 +20,14 @@
> #include <linux/sysfs.h>
> #include <linux/module.h>
> #include <linux/lcm.h>
> +#include <linux/swab.h>
>
> #include <linux/iio/iio.h>
> #include <linux/iio/sysfs.h>
> #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>
>
> @@ -103,6 +107,12 @@
> * 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
> +/* total number of segments in burst */
> +#define ADIS16495_BURST_MAX_DATA 20
> +/* spi max speed in burst mode */
> +#define ADIS16495_BURST_MAX_SPEED 6000000
>
> #define ADIS16480_REG_SERIAL_NUM ADIS16480_REG(0x04, 0x20)
>
> @@ -163,6 +173,8 @@ struct adis16480 {
> struct clk *ext_clk;
> enum adis16480_clock_mode clk_mode;
> unsigned int clk_freq;
> + /* Alignment needed for the timestamp */
> + __be16 data[ADIS16495_BURST_MAX_DATA] __aligned(8);
> };
>
> static const char * const adis16480_int_pin_names[4] = {
> @@ -863,7 +875,7 @@ static const char * const adis16480_status_error_msgs[] = {
>
> static int adis16480_enable_irq(struct adis *adis, bool enable);
>
> -#define ADIS16480_DATA(_prod_id, _timeouts) \
> +#define ADIS16480_DATA(_prod_id, _timeouts, _burst_len) \
> { \
> .diag_stat_reg = ADIS16480_REG_DIAG_STS, \
> .glob_cmd_reg = ADIS16480_REG_GLOB_CMD, \
> @@ -887,6 +899,8 @@ static int adis16480_enable_irq(struct adis *adis, bool enable);
> BIT(ADIS16480_DIAG_STAT_BARO_FAIL), \
> .enable_irq = adis16480_enable_irq, \
> .timeouts = (_timeouts), \
> + .burst_reg_cmd = ADIS16495_REG_BURST_CMD, \
> + .burst_len = (_burst_len), \
> }
>
> static const struct adis_timeout adis16485_timeouts = {
> @@ -931,7 +945,7 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
> .int_clk = 2460000,
> .max_dec_rate = 2048,
> .filter_freqs = adis16480_def_filter_freqs,
> - .adis_data = ADIS16480_DATA(16375, &adis16485_timeouts),
> + .adis_data = ADIS16480_DATA(16375, &adis16485_timeouts, 0),
> },
> [ADIS16480] = {
> .channels = adis16480_channels,
> @@ -944,7 +958,7 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
> .int_clk = 2460000,
> .max_dec_rate = 2048,
> .filter_freqs = adis16480_def_filter_freqs,
> - .adis_data = ADIS16480_DATA(16480, &adis16480_timeouts),
> + .adis_data = ADIS16480_DATA(16480, &adis16480_timeouts, 0),
> },
> [ADIS16485] = {
> .channels = adis16485_channels,
> @@ -957,7 +971,7 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
> .int_clk = 2460000,
> .max_dec_rate = 2048,
> .filter_freqs = adis16480_def_filter_freqs,
> - .adis_data = ADIS16480_DATA(16485, &adis16485_timeouts),
> + .adis_data = ADIS16480_DATA(16485, &adis16485_timeouts, 0),
> },
> [ADIS16488] = {
> .channels = adis16480_channels,
> @@ -970,7 +984,7 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
> .int_clk = 2460000,
> .max_dec_rate = 2048,
> .filter_freqs = adis16480_def_filter_freqs,
> - .adis_data = ADIS16480_DATA(16488, &adis16485_timeouts),
> + .adis_data = ADIS16480_DATA(16488, &adis16485_timeouts, 0),
> },
> [ADIS16490] = {
> .channels = adis16485_channels,
> @@ -984,7 +998,7 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
> .max_dec_rate = 4250,
> .filter_freqs = adis16495_def_filter_freqs,
> .has_pps_clk_mode = true,
> - .adis_data = ADIS16480_DATA(16490, &adis16495_timeouts),
> + .adis_data = ADIS16480_DATA(16490, &adis16495_timeouts, 0),
> },
> [ADIS16495_1] = {
> .channels = adis16485_channels,
> @@ -998,7 +1012,9 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
> .max_dec_rate = 4250,
> .filter_freqs = adis16495_def_filter_freqs,
> .has_pps_clk_mode = true,
> - .adis_data = ADIS16480_DATA(16495, &adis16495_1_timeouts),
> + /* 20 elements of 16bits */
> + .adis_data = ADIS16480_DATA(16495, &adis16495_1_timeouts,
> + ADIS16495_BURST_MAX_DATA * 2),
> },
> [ADIS16495_2] = {
> .channels = adis16485_channels,
> @@ -1012,7 +1028,9 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
> .max_dec_rate = 4250,
> .filter_freqs = adis16495_def_filter_freqs,
> .has_pps_clk_mode = true,
> - .adis_data = ADIS16480_DATA(16495, &adis16495_1_timeouts),
> + /* 20 elements of 16bits */
> + .adis_data = ADIS16480_DATA(16495, &adis16495_1_timeouts,
> + ADIS16495_BURST_MAX_DATA * 2),
> },
> [ADIS16495_3] = {
> .channels = adis16485_channels,
> @@ -1026,7 +1044,9 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
> .max_dec_rate = 4250,
> .filter_freqs = adis16495_def_filter_freqs,
> .has_pps_clk_mode = true,
> - .adis_data = ADIS16480_DATA(16495, &adis16495_1_timeouts),
> + /* 20 elements of 16bits */
> + .adis_data = ADIS16480_DATA(16495, &adis16495_1_timeouts,
> + ADIS16495_BURST_MAX_DATA * 2),
> },
> [ADIS16497_1] = {
> .channels = adis16485_channels,
> @@ -1040,7 +1060,9 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
> .max_dec_rate = 4250,
> .filter_freqs = adis16495_def_filter_freqs,
> .has_pps_clk_mode = true,
> - .adis_data = ADIS16480_DATA(16497, &adis16495_1_timeouts),
> + /* 20 elements of 16bits */
> + .adis_data = ADIS16480_DATA(16497, &adis16495_1_timeouts,
> + ADIS16495_BURST_MAX_DATA * 2),
> },
> [ADIS16497_2] = {
> .channels = adis16485_channels,
> @@ -1054,7 +1076,9 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
> .max_dec_rate = 4250,
> .filter_freqs = adis16495_def_filter_freqs,
> .has_pps_clk_mode = true,
> - .adis_data = ADIS16480_DATA(16497, &adis16495_1_timeouts),
> + /* 20 elements of 16bits */
> + .adis_data = ADIS16480_DATA(16497, &adis16495_1_timeouts,
> + ADIS16495_BURST_MAX_DATA * 2),
> },
> [ADIS16497_3] = {
> .channels = adis16485_channels,
> @@ -1068,10 +1092,121 @@ static const struct adis16480_chip_info adis16480_chip_info[] = {
> .max_dec_rate = 4250,
> .filter_freqs = adis16495_def_filter_freqs,
> .has_pps_clk_mode = true,
> - .adis_data = ADIS16480_DATA(16497, &adis16495_1_timeouts),
> + /* 20 elements of 16bits */
> + .adis_data = ADIS16480_DATA(16497, &adis16495_1_timeouts,
> + ADIS16495_BURST_MAX_DATA * 2),
> },
> };
>
> +static bool adis16480_validate_crc(const u16 *buf, const u8 n_elem, const u32 crc)
> +{
> + u32 crc_calc;
> + u16 crc_buf[15];
> + int j;
> +
> + for (j = 0; j < n_elem; j++)
> + crc_buf[j] = swab16(buf[j]);
> +
> + crc_calc = crc32(~0, crc_buf, n_elem * 2);
> + crc_calc ^= ~0;
> +
> + return (crc == crc_calc);
> +}
> +
> +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 *buffer;
> + u32 crc;
> + bool valid;
> + const u32 cached_spi_speed_hz = adis->spi->max_speed_hz;
> +
> + adis_dev_lock(adis);
> + if (adis->current_page != 0) {
> + adis->tx[0] = ADIS_WRITE_REG(ADIS_REG_PAGE_ID);
> + adis->tx[1] = 0;
> + ret = spi_write(adis->spi, adis->tx, 2);
> + if (ret) {
> + dev_err(&adis->spi->dev, "Failed to change device page: %d\n", ret);
> + adis_dev_unlock(adis);
> + return ret;
This is an interrupt handler, you should be careful what you return
as they will be treated as irqreturn_t not ints.
return IRQ_HANDLED even in error paths.
> + }
> + }
> +
> + adis->spi->max_speed_hz = ADIS16495_BURST_MAX_SPEED;
> +
> + ret = spi_sync(adis->spi, &adis->msg);
> + if (ret) {
> + dev_err(&adis->spi->dev, "Failed to read data: %d\n", ret);
> + adis_dev_unlock(adis);
> + return ret;
> + }
> +
> + adis->spi->max_speed_hz = cached_spi_speed_hz;
> + adis->current_page = 0;
Does it make more sense to move this to just after we changed the page?
If something more complex is going on, perhaps a comment here?
> + adis_dev_unlock(adis);
> +
> + /*
> + * After making the burst request, the response can have one or two
> + * 16-bit responses containing the BURST_ID depending on the sclk. If
> + * clk > 3.6MHz, then we will have two BURST_ID in a row. If clk < 3MHZ,
> + * we have only one. To manage that variation, we use the transition from the
> + * BURST_ID to the SYS_E_FLAG register, which will not be equal to 0xA5A5. If
> + * we not find this variation in the first 4 segments, then the data should
> + * not be valid.
> + */
> + buffer = adis->buffer;
> + for (offset = 0; offset < 4; offset++) {
> + u16 curr = be16_to_cpu(buffer[offset]);
> + u16 next = be16_to_cpu(buffer[offset + 1]);
> +
> + if (curr == ADIS16495_BURST_ID && next != ADIS16495_BURST_ID) {
> + offset++;
> + break;
> + }
> + }
> +
> + if (offset == 4) {
> + dev_err(&adis->spi->dev, "Invalid burst data\n");
> + goto irq_done;
> + }
> +
> + crc = be16_to_cpu(buffer[offset + 16]) << 16 | be16_to_cpu(buffer[offset + 15]);
> + valid = adis16480_validate_crc((u16 *)&buffer[offset], 15, crc);
> + if (!valid) {
> + dev_err(&adis->spi->dev, "Invalid crc\n");
> + goto irq_done;
> + }
> +
> + 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.
> + */
> + switch (bit) {
> + case ADIS16480_SCAN_TEMP:
> + st->data[i++] = buffer[offset + 1];
> + break;
> + case ADIS16480_SCAN_GYRO_X ... ADIS16480_SCAN_ACCEL_Z:
> + /* The lower register data is sequenced first */
> + st->data[i++] = buffer[2 * bit + offset + 3];
> + st->data[i++] = buffer[2 * bit + offset + 2];
> + break;
> + }
> + }
> +
> + iio_push_to_buffers_with_timestamp(indio_dev, st->data, pf->timestamp);
> +irq_done:
> + 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,
> @@ -1341,7 +1476,7 @@ static int adis16480_probe(struct spi_device *spi)
> st->clk_freq = st->chip_info->int_clk;
> }
>
> - ret = devm_adis_setup_buffer_and_trigger(&st->adis, indio_dev, NULL);
> + ret = devm_adis_setup_buffer_and_trigger(&st->adis, indio_dev, adis16480_trigger_handler);
Whilst 100 chars is fine, it's preferred to stay under 80 when it doesn't hurt readability
so I'd like to see this on two lines.
> if (ret)
> return ret;
>
next prev parent reply other threads:[~2021-04-11 14:39 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-08 7:56 [PATCH v2] iio: adis16480: support burst read function Nuno Sa
2021-04-09 6:52 ` Lars-Peter Clausen
2021-04-11 14:40 ` Jonathan Cameron [this message]
2021-04-12 7:33 ` Sa, Nuno
2021-04-12 10:18 ` Jonathan Cameron
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210411154002.159c4018@jic23-huawei \
--to=jic23@kernel.org \
--cc=Michael.Hennerich@analog.com \
--cc=lars@metafoo.de \
--cc=linux-iio@vger.kernel.org \
--cc=nuno.sa@analog.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox