Commit 31d7c17e authored by Jakub Kicinski's avatar Jakub Kicinski

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: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
parents bacb7e18 79591b7d
......@@ -1171,6 +1171,11 @@ static int spi_transfer_one_message(struct spi_controller *ctlr,
spi_statistics_add_transfer_stats(statm, xfer, ctlr);
spi_statistics_add_transfer_stats(stats, xfer, ctlr);
if (!ctlr->ptp_sts_supported) {
xfer->ptp_sts_word_pre = 0;
ptp_read_system_prets(xfer->ptp_sts);
}
if (xfer->tx_buf || xfer->rx_buf) {
reinit_completion(&ctlr->xfer_completion);
......@@ -1197,6 +1202,11 @@ static int spi_transfer_one_message(struct spi_controller *ctlr,
xfer->len);
}
if (!ctlr->ptp_sts_supported) {
ptp_read_system_postts(xfer->ptp_sts);
xfer->ptp_sts_word_post = xfer->len;
}
trace_spi_transfer_stop(msg, xfer);
if (msg->status != -EINPROGRESS)
......@@ -1265,6 +1275,7 @@ EXPORT_SYMBOL_GPL(spi_finalize_current_transfer);
*/
static void __spi_pump_messages(struct spi_controller *ctlr, bool in_kthread)
{
struct spi_transfer *xfer;
struct spi_message *msg;
bool was_busy = false;
unsigned long flags;
......@@ -1391,6 +1402,13 @@ static void __spi_pump_messages(struct spi_controller *ctlr, bool in_kthread)
goto out;
}
if (!ctlr->ptp_sts_supported && !ctlr->transfer_one) {
list_for_each_entry(xfer, &msg->transfers, transfer_list) {
xfer->ptp_sts_word_pre = 0;
ptp_read_system_prets(xfer->ptp_sts);
}
}
ret = ctlr->transfer_one_message(ctlr, msg);
if (ret) {
dev_err(&ctlr->dev,
......@@ -1418,6 +1436,99 @@ static void spi_pump_messages(struct kthread_work *work)
__spi_pump_messages(ctlr, true);
}
/**
* spi_take_timestamp_pre - helper for drivers to collect the beginning of the
* TX timestamp for the requested byte from the SPI
* transfer. The frequency with which this function
* must be called (once per word, once for the whole
* transfer, once per batch of words etc) is arbitrary
* as long as the @tx buffer offset is greater than or
* equal to the requested byte at the time of the
* call. The timestamp is only taken once, at the
* first such call. It is assumed that the driver
* advances its @tx buffer pointer monotonically.
* @ctlr: Pointer to the spi_controller structure of the driver
* @xfer: Pointer to the transfer being timestamped
* @tx: Pointer to the current word within the xfer->tx_buf that the driver is
* preparing to transmit right now.
* @irqs_off: If true, will disable IRQs and preemption for the duration of the
* transfer, for less jitter in time measurement. Only compatible
* with PIO drivers. If true, must follow up with
* spi_take_timestamp_post or otherwise system will crash.
* WARNING: for fully predictable results, the CPU frequency must
* also be under control (governor).
*/
void spi_take_timestamp_pre(struct spi_controller *ctlr,
struct spi_transfer *xfer,
const void *tx, bool irqs_off)
{
u8 bytes_per_word = DIV_ROUND_UP(xfer->bits_per_word, 8);
if (!xfer->ptp_sts)
return;
if (xfer->timestamped_pre)
return;
if (tx < (xfer->tx_buf + xfer->ptp_sts_word_pre * bytes_per_word))
return;
/* Capture the resolution of the timestamp */
xfer->ptp_sts_word_pre = (tx - xfer->tx_buf) / bytes_per_word;
xfer->timestamped_pre = true;
if (irqs_off) {
local_irq_save(ctlr->irq_flags);
preempt_disable();
}
ptp_read_system_prets(xfer->ptp_sts);
}
EXPORT_SYMBOL_GPL(spi_take_timestamp_pre);
/**
* spi_take_timestamp_post - helper for drivers to collect the end of the
* TX timestamp for the requested byte from the SPI
* transfer. Can be called with an arbitrary
* frequency: only the first call where @tx exceeds
* or is equal to the requested word will be
* timestamped.
* @ctlr: Pointer to the spi_controller structure of the driver
* @xfer: Pointer to the transfer being timestamped
* @tx: Pointer to the current word within the xfer->tx_buf that the driver has
* just transmitted.
* @irqs_off: If true, will re-enable IRQs and preemption for the local CPU.
*/
void spi_take_timestamp_post(struct spi_controller *ctlr,
struct spi_transfer *xfer,
const void *tx, bool irqs_off)
{
u8 bytes_per_word = DIV_ROUND_UP(xfer->bits_per_word, 8);
if (!xfer->ptp_sts)
return;
if (xfer->timestamped_post)
return;
if (tx < (xfer->tx_buf + xfer->ptp_sts_word_post * bytes_per_word))
return;
ptp_read_system_postts(xfer->ptp_sts);
if (irqs_off) {
local_irq_restore(ctlr->irq_flags);
preempt_enable();
}
/* Capture the resolution of the timestamp */
xfer->ptp_sts_word_post = (tx - xfer->tx_buf) / bytes_per_word;
xfer->timestamped_post = true;
}
EXPORT_SYMBOL_GPL(spi_take_timestamp_post);
/**
* spi_set_thread_rt - set the controller to pump at realtime priority
* @ctlr: controller to boost priority of
......@@ -1503,6 +1614,7 @@ EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
*/
void spi_finalize_current_message(struct spi_controller *ctlr)
{
struct spi_transfer *xfer;
struct spi_message *mesg;
unsigned long flags;
int ret;
......@@ -1511,6 +1623,13 @@ void spi_finalize_current_message(struct spi_controller *ctlr)
mesg = ctlr->cur_msg;
spin_unlock_irqrestore(&ctlr->queue_lock, flags);
if (!ctlr->ptp_sts_supported && !ctlr->transfer_one) {
list_for_each_entry(xfer, &mesg->transfers, transfer_list) {
ptp_read_system_postts(xfer->ptp_sts);
xfer->ptp_sts_word_post = xfer->len;
}
}
spi_unmap_msg(ctlr, mesg);
if (ctlr->cur_msg_prepared && ctlr->unprepare_message) {
......@@ -3273,6 +3392,7 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
static int __spi_async(struct spi_device *spi, struct spi_message *message)
{
struct spi_controller *ctlr = spi->controller;
struct spi_transfer *xfer;
/*
* Some controllers do not support doing regular SPI transfers. Return
......@@ -3288,6 +3408,13 @@ static int __spi_async(struct spi_device *spi, struct spi_message *message)
trace_spi_message_submit(message);
if (!ctlr->ptp_sts_supported) {
list_for_each_entry(xfer, &message->transfers, transfer_list) {
xfer->ptp_sts_word_pre = 0;
ptp_read_system_prets(xfer->ptp_sts);
}
}
return ctlr->transfer(spi, message);
}
......
......@@ -13,6 +13,7 @@
#include <linux/completion.h>
#include <linux/scatterlist.h>
#include <linux/gpio/consumer.h>
#include <linux/ptp_clock_kernel.h>
struct dma_chan;
struct property_entry;
......@@ -409,6 +410,12 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
* @fw_translate_cs: If the boot firmware uses different numbering scheme
* what Linux expects, this optional hook can be used to translate
* between the two.
* @ptp_sts_supported: If the driver sets this to true, it must provide a
* time snapshot in @spi_transfer->ptp_sts as close as possible to the
* moment in time when @spi_transfer->ptp_sts_word_pre and
* @spi_transfer->ptp_sts_word_post were transmitted.
* If the driver does not set this, the SPI core takes the snapshot as
* close to the driver hand-over as possible.
*
* Each SPI controller can communicate with one or more @spi_device
* children. These make a small bus, sharing MOSI, MISO and SCK signals
......@@ -604,6 +611,15 @@ struct spi_controller {
void *dummy_tx;
int (*fw_translate_cs)(struct spi_controller *ctlr, unsigned cs);
/*
* Driver sets this field to indicate it is able to snapshot SPI
* transfers (needed e.g. for reading the time of POSIX clocks)
*/
bool ptp_sts_supported;
/* Interrupt enable state during PTP system timestamping */
unsigned long irq_flags;
};
static inline void *spi_controller_get_devdata(struct spi_controller *ctlr)
......@@ -644,6 +660,14 @@ extern struct spi_message *spi_get_next_queued_message(struct spi_controller *ct
extern void spi_finalize_current_message(struct spi_controller *ctlr);
extern void spi_finalize_current_transfer(struct spi_controller *ctlr);
/* Helper calls for driver to timestamp transfer */
void spi_take_timestamp_pre(struct spi_controller *ctlr,
struct spi_transfer *xfer,
const void *tx, bool irqs_off);
void spi_take_timestamp_post(struct spi_controller *ctlr,
struct spi_transfer *xfer,
const void *tx, bool irqs_off);
/* the spi driver core manages memory for the spi_controller classdev */
extern struct spi_controller *__spi_alloc_controller(struct device *host,
unsigned int size, bool slave);
......@@ -753,6 +777,35 @@ extern void spi_res_release(struct spi_controller *ctlr,
* @transfer_list: transfers are sequenced through @spi_message.transfers
* @tx_sg: Scatterlist for transmit, currently not for client use
* @rx_sg: Scatterlist for receive, currently not for client use
* @ptp_sts_word_pre: The word (subject to bits_per_word semantics) offset
* within @tx_buf for which the SPI device is requesting that the time
* snapshot for this transfer begins. Upon completing the SPI transfer,
* this value may have changed compared to what was requested, depending
* on the available snapshotting resolution (DMA transfer,
* @ptp_sts_supported is false, etc).
* @ptp_sts_word_post: See @ptp_sts_word_post. The two can be equal (meaning
* that a single byte should be snapshotted).
* If the core takes care of the timestamp (if @ptp_sts_supported is false
* for this controller), it will set @ptp_sts_word_pre to 0, and
* @ptp_sts_word_post to the length of the transfer. This is done
* purposefully (instead of setting to spi_transfer->len - 1) to denote
* that a transfer-level snapshot taken from within the driver may still
* be of higher quality.
* @ptp_sts: Pointer to a memory location held by the SPI slave device where a
* PTP system timestamp structure may lie. If drivers use PIO or their
* hardware has some sort of assist for retrieving exact transfer timing,
* they can (and should) assert @ptp_sts_supported and populate this
* structure using the ptp_read_system_*ts helper functions.
* The timestamp must represent the time at which the SPI slave device has
* processed the word, i.e. the "pre" timestamp should be taken before
* transmitting the "pre" word, and the "post" timestamp after receiving
* transmit confirmation from the controller for the "post" word.
* @timestamped_pre: Set by the SPI controller driver to denote it has acted
* upon the @ptp_sts request. Not set when the SPI core has taken care of
* the task. SPI device drivers are free to print a warning if this comes
* back unset and they need the better resolution.
* @timestamped_post: See above. The reason why both exist is that these
* booleans are also used to keep state in the core SPI logic.
*
* SPI transfers always write the same number of bytes as they read.
* Protocol drivers should always provide @rx_buf and/or @tx_buf.
......@@ -842,6 +895,14 @@ struct spi_transfer {
u32 effective_speed_hz;
unsigned int ptp_sts_word_pre;
unsigned int ptp_sts_word_post;
struct ptp_system_timestamp *ptp_sts;
bool timestamped_pre;
bool timestamped_post;
struct list_head transfer_list;
};
......
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