spi: slave: Add SPI slave handler reporting uptime at previous message (29f9ffa0) · Commits · e / devices / android_kernel_xiaomi_nabu

drivers/spi/Kconfig

+6 −0

Original line number	Diff line number	Diff line
		@@ -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

drivers/spi/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -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

drivers/spi/spi-slave-time.c

0 → 100644

+129 −0

Original line number	Diff line number	Diff line
		/*
		* 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");