114 lines
2.6 KiB
C
114 lines
2.6 KiB
C
/*
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* Copyright (C) 2006 Juergen Beisert, Pengutronix
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* Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
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* Copyright (C) 2009 Wolfram Sang, Pengutronix
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* Check max730x.c for further details.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/platform_device.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/spi/spi.h>
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#include <linux/spi/max7301.h>
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/* A write to the MAX7301 means one message with one transfer */
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static int max7301_spi_write(struct device *dev, unsigned int reg,
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unsigned int val)
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{
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struct spi_device *spi = to_spi_device(dev);
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u16 word = ((reg & 0x7F) << 8) | (val & 0xFF);
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return spi_write(spi, (const u8 *)&word, sizeof(word));
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}
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/* A read from the MAX7301 means two transfers; here, one message each */
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static int max7301_spi_read(struct device *dev, unsigned int reg)
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{
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int ret;
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u16 word;
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struct spi_device *spi = to_spi_device(dev);
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word = 0x8000 | (reg << 8);
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ret = spi_write(spi, (const u8 *)&word, sizeof(word));
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if (ret)
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return ret;
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/*
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* This relies on the fact, that a transfer with NULL tx_buf shifts out
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* zero bytes (=NOOP for MAX7301)
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*/
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ret = spi_read(spi, (u8 *)&word, sizeof(word));
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if (ret)
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return ret;
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return word & 0xff;
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}
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static int max7301_probe(struct spi_device *spi)
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{
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struct max7301 *ts;
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int ret;
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/* bits_per_word cannot be configured in platform data */
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spi->bits_per_word = 16;
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ret = spi_setup(spi);
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if (ret < 0)
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return ret;
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ts = devm_kzalloc(&spi->dev, sizeof(struct max7301), GFP_KERNEL);
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if (!ts)
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return -ENOMEM;
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ts->read = max7301_spi_read;
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ts->write = max7301_spi_write;
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ts->dev = &spi->dev;
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ret = __max730x_probe(ts);
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return ret;
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}
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static int max7301_remove(struct spi_device *spi)
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{
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return __max730x_remove(&spi->dev);
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}
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static const struct spi_device_id max7301_id[] = {
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{ "max7301", 0 },
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{ }
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};
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MODULE_DEVICE_TABLE(spi, max7301_id);
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static struct spi_driver max7301_driver = {
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.driver = {
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.name = "max7301",
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},
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.probe = max7301_probe,
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.remove = max7301_remove,
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.id_table = max7301_id,
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};
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static int __init max7301_init(void)
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{
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return spi_register_driver(&max7301_driver);
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}
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/* register after spi postcore initcall and before
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* subsys initcalls that may rely on these GPIOs
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*/
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subsys_initcall(max7301_init);
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static void __exit max7301_exit(void)
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{
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spi_unregister_driver(&max7301_driver);
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}
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module_exit(max7301_exit);
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MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
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MODULE_LICENSE("GPL v2");
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MODULE_DESCRIPTION("MAX7301 GPIO-Expander");
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