diff options
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/Kconfig | 6 | ||||
| -rw-r--r-- | drivers/spi/Makefile | 1 | ||||
| -rw-r--r-- | drivers/spi/spi-slave-time.c | 129 |
3 files changed, 136 insertions, 0 deletions
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig index df8ddec24b5d..ade542c5bfd8 100644 --- a/drivers/spi/Kconfig +++ b/drivers/spi/Kconfig @@ -796,6 +796,12 @@ config SPI_SLAVE if SPI_SLAVE +config SPI_SLAVE_TIME + tristate "SPI slave handler reporting boot up time" + help + SPI slave handler responding with the time of reception of the last + SPI message. + endif # SPI_SLAVE endif # SPI diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile index e50852c6fcb8..fb078693dbe4 100644 --- a/drivers/spi/Makefile +++ b/drivers/spi/Makefile @@ -107,3 +107,4 @@ obj-$(CONFIG_SPI_XTENSA_XTFPGA) += spi-xtensa-xtfpga.o obj-$(CONFIG_SPI_ZYNQMP_GQSPI) += spi-zynqmp-gqspi.o # SPI slave protocol handlers +obj-$(CONFIG_SPI_SLAVE_TIME) += spi-slave-time.o diff --git a/drivers/spi/spi-slave-time.c b/drivers/spi/spi-slave-time.c new file mode 100644 index 000000000000..f2e07a392d68 --- /dev/null +++ b/drivers/spi/spi-slave-time.c @@ -0,0 +1,129 @@ +/* + * SPI slave handler reporting uptime at reception of previous SPI message + * + * This SPI slave handler sends the time of reception of the last SPI message + * as two 32-bit unsigned integers in binary format and in network byte order, + * representing the number of seconds and fractional seconds (in microseconds) + * since boot up. + * + * Copyright (C) 2016-2017 Glider bvba + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Usage (assuming /dev/spidev2.0 corresponds to the SPI master on the remote + * system): + * + * # spidev_test -D /dev/spidev2.0 -p dummy-8B + * spi mode: 0x0 + * bits per word: 8 + * max speed: 500000 Hz (500 KHz) + * RX | 00 00 04 6D 00 09 5B BB ... + * ^^^^^ ^^^^^^^^ + * seconds microseconds + */ + +#include <linux/completion.h> +#include <linux/module.h> +#include <linux/sched/clock.h> +#include <linux/spi/spi.h> + + +struct spi_slave_time_priv { + struct spi_device *spi; + struct completion finished; + struct spi_transfer xfer; + struct spi_message msg; + __be32 buf[2]; +}; + +static int spi_slave_time_submit(struct spi_slave_time_priv *priv); + +static void spi_slave_time_complete(void *arg) +{ + struct spi_slave_time_priv *priv = arg; + int ret; + + ret = priv->msg.status; + if (ret) + goto terminate; + + ret = spi_slave_time_submit(priv); + if (ret) + goto terminate; + + return; + +terminate: + dev_info(&priv->spi->dev, "Terminating\n"); + complete(&priv->finished); +} + +static int spi_slave_time_submit(struct spi_slave_time_priv *priv) +{ + u32 rem_us; + int ret; + u64 ts; + + ts = local_clock(); + rem_us = do_div(ts, 1000000000) / 1000; + + priv->buf[0] = cpu_to_be32(ts); + priv->buf[1] = cpu_to_be32(rem_us); + + spi_message_init_with_transfers(&priv->msg, &priv->xfer, 1); + + priv->msg.complete = spi_slave_time_complete; + priv->msg.context = priv; + + ret = spi_async(priv->spi, &priv->msg); + if (ret) + dev_err(&priv->spi->dev, "spi_async() failed %d\n", ret); + + return ret; +} + +static int spi_slave_time_probe(struct spi_device *spi) +{ + struct spi_slave_time_priv *priv; + int ret; + + priv = devm_kzalloc(&spi->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->spi = spi; + init_completion(&priv->finished); + priv->xfer.tx_buf = priv->buf; + priv->xfer.len = sizeof(priv->buf); + + ret = spi_slave_time_submit(priv); + if (ret) + return ret; + + spi_set_drvdata(spi, priv); + return 0; +} + +static int spi_slave_time_remove(struct spi_device *spi) +{ + struct spi_slave_time_priv *priv = spi_get_drvdata(spi); + + spi_slave_abort(spi); + wait_for_completion(&priv->finished); + return 0; +} + +static struct spi_driver spi_slave_time_driver = { + .driver = { + .name = "spi-slave-time", + }, + .probe = spi_slave_time_probe, + .remove = spi_slave_time_remove, +}; +module_spi_driver(spi_slave_time_driver); + +MODULE_AUTHOR("Geert Uytterhoeven <geert+renesas@glider.be>"); +MODULE_DESCRIPTION("SPI slave reporting uptime at previous SPI message"); +MODULE_LICENSE("GPL v2"); |