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129 lines
2.9 KiB
129 lines
2.9 KiB
/* |
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* SPI slave handler reporting uptime at reception of previous SPI message |
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* |
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* This SPI slave handler sends the time of reception of the last SPI message |
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* as two 32-bit unsigned integers in binary format and in network byte order, |
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* representing the number of seconds and fractional seconds (in microseconds) |
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* since boot up. |
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* |
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* Copyright (C) 2016-2017 Glider bvba |
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* |
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* This file is subject to the terms and conditions of the GNU General Public |
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* License. See the file "COPYING" in the main directory of this archive |
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* for more details. |
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* |
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* Usage (assuming /dev/spidev2.0 corresponds to the SPI master on the remote |
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* system): |
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* |
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* # spidev_test -D /dev/spidev2.0 -p dummy-8B |
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* spi mode: 0x0 |
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* bits per word: 8 |
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* max speed: 500000 Hz (500 KHz) |
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* RX | 00 00 04 6D 00 09 5B BB ... |
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* ^^^^^ ^^^^^^^^ |
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* seconds microseconds |
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*/ |
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#include <linux/completion.h> |
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#include <linux/module.h> |
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#include <linux/sched/clock.h> |
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#include <linux/spi/spi.h> |
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struct spi_slave_time_priv { |
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struct spi_device *spi; |
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struct completion finished; |
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struct spi_transfer xfer; |
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struct spi_message msg; |
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__be32 buf[2]; |
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}; |
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static int spi_slave_time_submit(struct spi_slave_time_priv *priv); |
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static void spi_slave_time_complete(void *arg) |
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{ |
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struct spi_slave_time_priv *priv = arg; |
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int ret; |
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ret = priv->msg.status; |
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if (ret) |
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goto terminate; |
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ret = spi_slave_time_submit(priv); |
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if (ret) |
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goto terminate; |
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return; |
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terminate: |
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dev_info(&priv->spi->dev, "Terminating\n"); |
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complete(&priv->finished); |
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} |
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static int spi_slave_time_submit(struct spi_slave_time_priv *priv) |
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{ |
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u32 rem_us; |
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int ret; |
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u64 ts; |
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ts = local_clock(); |
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rem_us = do_div(ts, 1000000000) / 1000; |
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priv->buf[0] = cpu_to_be32(ts); |
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priv->buf[1] = cpu_to_be32(rem_us); |
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spi_message_init_with_transfers(&priv->msg, &priv->xfer, 1); |
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priv->msg.complete = spi_slave_time_complete; |
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priv->msg.context = priv; |
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ret = spi_async(priv->spi, &priv->msg); |
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if (ret) |
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dev_err(&priv->spi->dev, "spi_async() failed %d\n", ret); |
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return ret; |
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} |
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static int spi_slave_time_probe(struct spi_device *spi) |
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{ |
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struct spi_slave_time_priv *priv; |
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int ret; |
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priv = devm_kzalloc(&spi->dev, sizeof(*priv), GFP_KERNEL); |
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if (!priv) |
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return -ENOMEM; |
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priv->spi = spi; |
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init_completion(&priv->finished); |
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priv->xfer.tx_buf = priv->buf; |
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priv->xfer.len = sizeof(priv->buf); |
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ret = spi_slave_time_submit(priv); |
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if (ret) |
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return ret; |
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spi_set_drvdata(spi, priv); |
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return 0; |
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} |
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static int spi_slave_time_remove(struct spi_device *spi) |
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{ |
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struct spi_slave_time_priv *priv = spi_get_drvdata(spi); |
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spi_slave_abort(spi); |
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wait_for_completion(&priv->finished); |
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return 0; |
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} |
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static struct spi_driver spi_slave_time_driver = { |
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.driver = { |
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.name = "spi-slave-time", |
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}, |
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.probe = spi_slave_time_probe, |
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.remove = spi_slave_time_remove, |
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}; |
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module_spi_driver(spi_slave_time_driver); |
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MODULE_AUTHOR("Geert Uytterhoeven <[email protected]>"); |
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MODULE_DESCRIPTION("SPI slave reporting uptime at previous SPI message"); |
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MODULE_LICENSE("GPL v2");
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