[linux.git] / drivers / spi / spi-slave-time.c

/*
 * 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 <[email protected]>");
MODULE_DESCRIPTION("SPI slave reporting uptime at previous SPI message");
MODULE_LICENSE("GPL v2");
Commit	Line	Data
29f9ffa0 GU	1	/*
	2	* SPI slave handler reporting uptime at reception of previous SPI message
	3	*
	4	* This SPI slave handler sends the time of reception of the last SPI message
	5	* as two 32-bit unsigned integers in binary format and in network byte order,
	6	* representing the number of seconds and fractional seconds (in microseconds)
	7	* since boot up.
	8	*
	9	* Copyright (C) 2016-2017 Glider bvba
	10	*
	11	* This file is subject to the terms and conditions of the GNU General Public
	12	* License. See the file "COPYING" in the main directory of this archive
	13	* for more details.
	14	*
	15	* Usage (assuming /dev/spidev2.0 corresponds to the SPI master on the remote
	16	* system):
	17	*
	18	* # spidev_test -D /dev/spidev2.0 -p dummy-8B
	19	* spi mode: 0x0
	20	* bits per word: 8
	21	* max speed: 500000 Hz (500 KHz)
	22	* RX \| 00 00 04 6D 00 09 5B BB ...
	23	* ^^^^^ ^^^^^^^^
	24	* seconds microseconds
	25	*/
	26
	27	#include <linux/completion.h>
	28	#include <linux/module.h>
	29	#include <linux/sched/clock.h>
	30	#include <linux/spi/spi.h>
	31
	32
	33	struct spi_slave_time_priv {
	34	struct spi_device *spi;
	35	struct completion finished;
	36	struct spi_transfer xfer;
	37	struct spi_message msg;
	38	__be32 buf[2];
	39	};
	40
	41	static int spi_slave_time_submit(struct spi_slave_time_priv *priv);
	42
	43	static void spi_slave_time_complete(void *arg)
	44	{
	45	struct spi_slave_time_priv *priv = arg;
	46	int ret;
	47
	48	ret = priv->msg.status;
	49	if (ret)
	50	goto terminate;
	51
	52	ret = spi_slave_time_submit(priv);
	53	if (ret)
	54	goto terminate;
	55
	56	return;
	57
	58	terminate:
	59	dev_info(&priv->spi->dev, "Terminating\n");
	60	complete(&priv->finished);
	61	}
	62
	63	static int spi_slave_time_submit(struct spi_slave_time_priv *priv)
	64	{
65	u32 rem_us;
66	int ret;
67	u64 ts;
68
69	ts = local_clock();
70	rem_us = do_div(ts, 1000000000) / 1000;
71
72	priv->buf[0] = cpu_to_be32(ts);
73	priv->buf[1] = cpu_to_be32(rem_us);
74
75	spi_message_init_with_transfers(&priv->msg, &priv->xfer, 1);
76
77	priv->msg.complete = spi_slave_time_complete;
78	priv->msg.context = priv;
79
80	ret = spi_async(priv->spi, &priv->msg);
81	if (ret)
82	dev_err(&priv->spi->dev, "spi_async() failed %d\n", ret);
83
84	return ret;
85	}
86
87	static int spi_slave_time_probe(struct spi_device *spi)
88	{
89	struct spi_slave_time_priv *priv;
90	int ret;
91
92	priv = devm_kzalloc(&spi->dev, sizeof(*priv), GFP_KERNEL);
93	if (!priv)
94	return -ENOMEM;
95
96	priv->spi = spi;
97	init_completion(&priv->finished);
98	priv->xfer.tx_buf = priv->buf;
99	priv->xfer.len = sizeof(priv->buf);
100
101	ret = spi_slave_time_submit(priv);
102	if (ret)
103	return ret;
104
105	spi_set_drvdata(spi, priv);
106	return 0;
107	}
108
109	static int spi_slave_time_remove(struct spi_device *spi)
110	{
111	struct spi_slave_time_priv *priv = spi_get_drvdata(spi);
112
113	spi_slave_abort(spi);
114	wait_for_completion(&priv->finished);
115	return 0;
116	}
117
118	static struct spi_driver spi_slave_time_driver = {
119	.driver = {
120	.name = "spi-slave-time",
121	},
122	.probe = spi_slave_time_probe,
123	.remove = spi_slave_time_remove,
124	};
125	module_spi_driver(spi_slave_time_driver);
126
127	MODULE_AUTHOR("Geert Uytterhoeven <[email protected]>");
128	MODULE_DESCRIPTION("SPI slave reporting uptime at previous SPI message");
129	MODULE_LICENSE("GPL v2");