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spi: Add a PTP API
For detailed timestamping of operations. -----BEGIN PGP SIGNATURE----- iQFHBAABCgAxFiEEreZoqmdXGLWf4p/qJNaLcl1Uh9AFAl2cu5ATHGJyb29uaWVA a2VybmVsLm9yZwAKCRAk1otyXVSH0HYXB/49vT69JJt0wGHR9HOjThnyUHU8s5D2 dJE6lsAbOY8zmGGE5b8yF78fHSA6NrXUWIK6/bNExSfNjwdwrJuVEcxJoi3HtcZA AWxAvpgR55HETiwudEN5ZxUw6FG5O+XAt0Eh7I4Gd+NaMbKrVDfy/cy3J78NK5Cr tDsOamv/nuaCVmoXxthU/u4wQTctBSvbeHMJWUePC/TOMnhxBmNrbsv6kDaQoE2A dWIYjgeUY4s/518Zv//AAhMUsi11N6V3pDyr3MIZJLTh7DDiDgaxx5OUpn6Xgi6Z vSeq7+elh5C9Ta6yg/DQnk8ZPhrHbFdvUiBps8+u1E/tAo6z70YISfcs =P2Sr -----END PGP SIGNATURE----- Merge tag 'spi-ptp-api' of https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi Pull in a dependency for Vladimir's work on more precise packet time stamping. Mark Brown says: ==================== spi: Add a PTP API For detailed timestamping of operations. ==================== Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
This commit is contained in:
Jakub Kicinski
commit
31d7c17e3f
@ -1171,6 +1171,11 @@ static int spi_transfer_one_message(struct spi_controller *ctlr,
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spi_statistics_add_transfer_stats(statm, xfer, ctlr);
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spi_statistics_add_transfer_stats(stats, xfer, ctlr);
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if (!ctlr->ptp_sts_supported) {
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xfer->ptp_sts_word_pre = 0;
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ptp_read_system_prets(xfer->ptp_sts);
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}
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if (xfer->tx_buf || xfer->rx_buf) {
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reinit_completion(&ctlr->xfer_completion);
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@ -1197,6 +1202,11 @@ static int spi_transfer_one_message(struct spi_controller *ctlr,
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xfer->len);
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}
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if (!ctlr->ptp_sts_supported) {
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ptp_read_system_postts(xfer->ptp_sts);
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xfer->ptp_sts_word_post = xfer->len;
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}
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trace_spi_transfer_stop(msg, xfer);
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if (msg->status != -EINPROGRESS)
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@ -1265,6 +1275,7 @@ EXPORT_SYMBOL_GPL(spi_finalize_current_transfer);
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*/
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static void __spi_pump_messages(struct spi_controller *ctlr, bool in_kthread)
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{
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struct spi_transfer *xfer;
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struct spi_message *msg;
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bool was_busy = false;
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unsigned long flags;
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@ -1391,6 +1402,13 @@ static void __spi_pump_messages(struct spi_controller *ctlr, bool in_kthread)
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goto out;
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}
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if (!ctlr->ptp_sts_supported && !ctlr->transfer_one) {
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list_for_each_entry(xfer, &msg->transfers, transfer_list) {
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xfer->ptp_sts_word_pre = 0;
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ptp_read_system_prets(xfer->ptp_sts);
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}
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}
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ret = ctlr->transfer_one_message(ctlr, msg);
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if (ret) {
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dev_err(&ctlr->dev,
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@ -1418,6 +1436,99 @@ static void spi_pump_messages(struct kthread_work *work)
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__spi_pump_messages(ctlr, true);
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}
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/**
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* spi_take_timestamp_pre - helper for drivers to collect the beginning of the
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* TX timestamp for the requested byte from the SPI
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* transfer. The frequency with which this function
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* must be called (once per word, once for the whole
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* transfer, once per batch of words etc) is arbitrary
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* as long as the @tx buffer offset is greater than or
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* equal to the requested byte at the time of the
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* call. The timestamp is only taken once, at the
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* first such call. It is assumed that the driver
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* advances its @tx buffer pointer monotonically.
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* @ctlr: Pointer to the spi_controller structure of the driver
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* @xfer: Pointer to the transfer being timestamped
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* @tx: Pointer to the current word within the xfer->tx_buf that the driver is
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* preparing to transmit right now.
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* @irqs_off: If true, will disable IRQs and preemption for the duration of the
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* transfer, for less jitter in time measurement. Only compatible
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* with PIO drivers. If true, must follow up with
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* spi_take_timestamp_post or otherwise system will crash.
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* WARNING: for fully predictable results, the CPU frequency must
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* also be under control (governor).
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*/
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void spi_take_timestamp_pre(struct spi_controller *ctlr,
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struct spi_transfer *xfer,
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const void *tx, bool irqs_off)
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{
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u8 bytes_per_word = DIV_ROUND_UP(xfer->bits_per_word, 8);
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if (!xfer->ptp_sts)
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return;
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if (xfer->timestamped_pre)
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return;
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if (tx < (xfer->tx_buf + xfer->ptp_sts_word_pre * bytes_per_word))
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return;
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/* Capture the resolution of the timestamp */
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xfer->ptp_sts_word_pre = (tx - xfer->tx_buf) / bytes_per_word;
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xfer->timestamped_pre = true;
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if (irqs_off) {
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local_irq_save(ctlr->irq_flags);
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preempt_disable();
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}
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ptp_read_system_prets(xfer->ptp_sts);
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}
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EXPORT_SYMBOL_GPL(spi_take_timestamp_pre);
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/**
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* spi_take_timestamp_post - helper for drivers to collect the end of the
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* TX timestamp for the requested byte from the SPI
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* transfer. Can be called with an arbitrary
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* frequency: only the first call where @tx exceeds
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* or is equal to the requested word will be
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* timestamped.
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* @ctlr: Pointer to the spi_controller structure of the driver
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* @xfer: Pointer to the transfer being timestamped
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* @tx: Pointer to the current word within the xfer->tx_buf that the driver has
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* just transmitted.
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* @irqs_off: If true, will re-enable IRQs and preemption for the local CPU.
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*/
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void spi_take_timestamp_post(struct spi_controller *ctlr,
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struct spi_transfer *xfer,
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const void *tx, bool irqs_off)
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{
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u8 bytes_per_word = DIV_ROUND_UP(xfer->bits_per_word, 8);
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if (!xfer->ptp_sts)
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return;
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if (xfer->timestamped_post)
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return;
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if (tx < (xfer->tx_buf + xfer->ptp_sts_word_post * bytes_per_word))
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return;
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ptp_read_system_postts(xfer->ptp_sts);
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if (irqs_off) {
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local_irq_restore(ctlr->irq_flags);
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preempt_enable();
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}
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/* Capture the resolution of the timestamp */
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xfer->ptp_sts_word_post = (tx - xfer->tx_buf) / bytes_per_word;
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xfer->timestamped_post = true;
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}
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EXPORT_SYMBOL_GPL(spi_take_timestamp_post);
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/**
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* spi_set_thread_rt - set the controller to pump at realtime priority
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* @ctlr: controller to boost priority of
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@ -1503,6 +1614,7 @@ EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
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*/
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void spi_finalize_current_message(struct spi_controller *ctlr)
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{
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struct spi_transfer *xfer;
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struct spi_message *mesg;
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unsigned long flags;
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int ret;
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@ -1511,6 +1623,13 @@ void spi_finalize_current_message(struct spi_controller *ctlr)
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mesg = ctlr->cur_msg;
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spin_unlock_irqrestore(&ctlr->queue_lock, flags);
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if (!ctlr->ptp_sts_supported && !ctlr->transfer_one) {
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list_for_each_entry(xfer, &mesg->transfers, transfer_list) {
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ptp_read_system_postts(xfer->ptp_sts);
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xfer->ptp_sts_word_post = xfer->len;
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}
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}
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spi_unmap_msg(ctlr, mesg);
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if (ctlr->cur_msg_prepared && ctlr->unprepare_message) {
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@ -3273,6 +3392,7 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
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static int __spi_async(struct spi_device *spi, struct spi_message *message)
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{
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struct spi_controller *ctlr = spi->controller;
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struct spi_transfer *xfer;
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/*
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* Some controllers do not support doing regular SPI transfers. Return
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@ -3288,6 +3408,13 @@ static int __spi_async(struct spi_device *spi, struct spi_message *message)
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trace_spi_message_submit(message);
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if (!ctlr->ptp_sts_supported) {
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list_for_each_entry(xfer, &message->transfers, transfer_list) {
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xfer->ptp_sts_word_pre = 0;
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ptp_read_system_prets(xfer->ptp_sts);
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}
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}
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return ctlr->transfer(spi, message);
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}
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@ -13,6 +13,7 @@
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#include <linux/completion.h>
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#include <linux/scatterlist.h>
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#include <linux/gpio/consumer.h>
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#include <linux/ptp_clock_kernel.h>
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struct dma_chan;
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struct property_entry;
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@ -409,6 +410,12 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
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* @fw_translate_cs: If the boot firmware uses different numbering scheme
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* what Linux expects, this optional hook can be used to translate
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* between the two.
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* @ptp_sts_supported: If the driver sets this to true, it must provide a
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* time snapshot in @spi_transfer->ptp_sts as close as possible to the
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* moment in time when @spi_transfer->ptp_sts_word_pre and
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* @spi_transfer->ptp_sts_word_post were transmitted.
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* If the driver does not set this, the SPI core takes the snapshot as
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* close to the driver hand-over as possible.
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*
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* Each SPI controller can communicate with one or more @spi_device
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* children. These make a small bus, sharing MOSI, MISO and SCK signals
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@ -604,6 +611,15 @@ struct spi_controller {
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void *dummy_tx;
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int (*fw_translate_cs)(struct spi_controller *ctlr, unsigned cs);
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/*
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* Driver sets this field to indicate it is able to snapshot SPI
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* transfers (needed e.g. for reading the time of POSIX clocks)
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*/
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bool ptp_sts_supported;
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/* Interrupt enable state during PTP system timestamping */
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unsigned long irq_flags;
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};
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static inline void *spi_controller_get_devdata(struct spi_controller *ctlr)
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@ -644,6 +660,14 @@ extern struct spi_message *spi_get_next_queued_message(struct spi_controller *ct
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extern void spi_finalize_current_message(struct spi_controller *ctlr);
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extern void spi_finalize_current_transfer(struct spi_controller *ctlr);
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/* Helper calls for driver to timestamp transfer */
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void spi_take_timestamp_pre(struct spi_controller *ctlr,
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struct spi_transfer *xfer,
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const void *tx, bool irqs_off);
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void spi_take_timestamp_post(struct spi_controller *ctlr,
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struct spi_transfer *xfer,
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const void *tx, bool irqs_off);
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/* the spi driver core manages memory for the spi_controller classdev */
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extern struct spi_controller *__spi_alloc_controller(struct device *host,
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unsigned int size, bool slave);
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@ -753,6 +777,35 @@ extern void spi_res_release(struct spi_controller *ctlr,
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* @transfer_list: transfers are sequenced through @spi_message.transfers
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* @tx_sg: Scatterlist for transmit, currently not for client use
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* @rx_sg: Scatterlist for receive, currently not for client use
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* @ptp_sts_word_pre: The word (subject to bits_per_word semantics) offset
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* within @tx_buf for which the SPI device is requesting that the time
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* snapshot for this transfer begins. Upon completing the SPI transfer,
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* this value may have changed compared to what was requested, depending
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* on the available snapshotting resolution (DMA transfer,
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* @ptp_sts_supported is false, etc).
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* @ptp_sts_word_post: See @ptp_sts_word_post. The two can be equal (meaning
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* that a single byte should be snapshotted).
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* If the core takes care of the timestamp (if @ptp_sts_supported is false
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* for this controller), it will set @ptp_sts_word_pre to 0, and
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* @ptp_sts_word_post to the length of the transfer. This is done
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* purposefully (instead of setting to spi_transfer->len - 1) to denote
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* that a transfer-level snapshot taken from within the driver may still
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* be of higher quality.
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* @ptp_sts: Pointer to a memory location held by the SPI slave device where a
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* PTP system timestamp structure may lie. If drivers use PIO or their
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* hardware has some sort of assist for retrieving exact transfer timing,
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* they can (and should) assert @ptp_sts_supported and populate this
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* structure using the ptp_read_system_*ts helper functions.
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* The timestamp must represent the time at which the SPI slave device has
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* processed the word, i.e. the "pre" timestamp should be taken before
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* transmitting the "pre" word, and the "post" timestamp after receiving
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* transmit confirmation from the controller for the "post" word.
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* @timestamped_pre: Set by the SPI controller driver to denote it has acted
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* upon the @ptp_sts request. Not set when the SPI core has taken care of
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* the task. SPI device drivers are free to print a warning if this comes
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* back unset and they need the better resolution.
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* @timestamped_post: See above. The reason why both exist is that these
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* booleans are also used to keep state in the core SPI logic.
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*
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* SPI transfers always write the same number of bytes as they read.
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* Protocol drivers should always provide @rx_buf and/or @tx_buf.
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@ -842,6 +895,14 @@ struct spi_transfer {
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u32 effective_speed_hz;
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unsigned int ptp_sts_word_pre;
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unsigned int ptp_sts_word_post;
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struct ptp_system_timestamp *ptp_sts;
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bool timestamped_pre;
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bool timestamped_post;
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struct list_head transfer_list;
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};
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