| Message ID | 1495458705-11692-6-git-send-email-geert+renesas@glider.be (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 29f9ffa0e1f9a17c866c04a01acfc9976d78f29a |
| Headers | show |
On Mon, May 22, 2017 at 4:11 PM, Geert Uytterhoeven <geert+renesas@glider.be> wrote: > Add an example SPI slave handler responding with the uptime at the time > of reception of the last SPI message. > > This can be used by an external microcontroller as a dead man's switch. > FWIW: Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> > --- > v5: > - Add usage documentation to file header, > - Replace pr_*() by dev_*(), stop printing __func__, > - Rename rem_ns to rem_us, as the remainder is in microseconds, > - Remove spi_setup() call to configure 8 bits per word, as that's the > default, > > v4: > - No changes, > > v3: > - Add #include <linux/sched/clock.h>, > > v2: > - Resolve semantic differences in patch description, file header, and > module description, > - Use spi_async() instead of spi_read(), > - Submit the next transfer from the previous transfer's completion > callback, removing the need for a thread, > - Let .remove() call spi_slave_abort() to cancel the current ongoing > transfer, and wait for the completion to terminate, > - Remove FIXME about hanging kthread_stop(). > --- > drivers/spi/Kconfig | 6 ++ > drivers/spi/Makefile | 1 + > drivers/spi/spi-slave-time.c | 129 +++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 136 insertions(+) > create mode 100644 drivers/spi/spi-slave-time.c > > diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig > index f21499b1f71ab7c3..9972ee2a8454a2fc 100644 > --- a/drivers/spi/Kconfig > +++ b/drivers/spi/Kconfig > @@ -797,6 +797,12 @@ 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 e50852c6fcb87d8b..fb078693dbe40da4 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 0000000000000000..f2e07a392d6863ea > --- /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"); > -- > 2.7.4 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-spi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig index f21499b1f71ab7c3..9972ee2a8454a2fc 100644 --- a/drivers/spi/Kconfig +++ b/drivers/spi/Kconfig @@ -797,6 +797,12 @@ 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 e50852c6fcb87d8b..fb078693dbe40da4 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 0000000000000000..f2e07a392d6863ea --- /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");
Add an example SPI slave handler responding with the uptime at the time of reception of the last SPI message. This can be used by an external microcontroller as a dead man's switch. Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> --- v5: - Add usage documentation to file header, - Replace pr_*() by dev_*(), stop printing __func__, - Rename rem_ns to rem_us, as the remainder is in microseconds, - Remove spi_setup() call to configure 8 bits per word, as that's the default, v4: - No changes, v3: - Add #include <linux/sched/clock.h>, v2: - Resolve semantic differences in patch description, file header, and module description, - Use spi_async() instead of spi_read(), - Submit the next transfer from the previous transfer's completion callback, removing the need for a thread, - Let .remove() call spi_slave_abort() to cancel the current ongoing transfer, and wait for the completion to terminate, - Remove FIXME about hanging kthread_stop(). --- drivers/spi/Kconfig | 6 ++ drivers/spi/Makefile | 1 + drivers/spi/spi-slave-time.c | 129 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 136 insertions(+) create mode 100644 drivers/spi/spi-slave-time.c