cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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gpio-max7301.c (2392B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Copyright (C) 2006 Juergen Beisert, Pengutronix
      4 * Copyright (C) 2008 Guennadi Liakhovetski, Pengutronix
      5 * Copyright (C) 2009 Wolfram Sang, Pengutronix
      6 *
      7 * Check max730x.c for further details.
      8 */
      9
     10#include <linux/module.h>
     11#include <linux/init.h>
     12#include <linux/platform_device.h>
     13#include <linux/mutex.h>
     14#include <linux/slab.h>
     15#include <linux/spi/spi.h>
     16#include <linux/spi/max7301.h>
     17
     18/* A write to the MAX7301 means one message with one transfer */
     19static int max7301_spi_write(struct device *dev, unsigned int reg,
     20				unsigned int val)
     21{
     22	struct spi_device *spi = to_spi_device(dev);
     23	u16 word = ((reg & 0x7F) << 8) | (val & 0xFF);
     24
     25	return spi_write_then_read(spi, &word, sizeof(word), NULL, 0);
     26}
     27
     28/* A read from the MAX7301 means two transfers; here, one message each */
     29
     30static int max7301_spi_read(struct device *dev, unsigned int reg)
     31{
     32	int ret;
     33	u16 word;
     34	struct spi_device *spi = to_spi_device(dev);
     35
     36	word = 0x8000 | (reg << 8);
     37	ret = spi_write_then_read(spi, &word, sizeof(word), &word,
     38				  sizeof(word));
     39	if (ret)
     40		return ret;
     41	return word & 0xff;
     42}
     43
     44static int max7301_probe(struct spi_device *spi)
     45{
     46	struct max7301 *ts;
     47	int ret;
     48
     49	/* bits_per_word cannot be configured in platform data */
     50	spi->bits_per_word = 16;
     51	ret = spi_setup(spi);
     52	if (ret < 0)
     53		return ret;
     54
     55	ts = devm_kzalloc(&spi->dev, sizeof(struct max7301), GFP_KERNEL);
     56	if (!ts)
     57		return -ENOMEM;
     58
     59	ts->read = max7301_spi_read;
     60	ts->write = max7301_spi_write;
     61	ts->dev = &spi->dev;
     62
     63	ret = __max730x_probe(ts);
     64	return ret;
     65}
     66
     67static void max7301_remove(struct spi_device *spi)
     68{
     69	__max730x_remove(&spi->dev);
     70}
     71
     72static const struct spi_device_id max7301_id[] = {
     73	{ "max7301", 0 },
     74	{ }
     75};
     76MODULE_DEVICE_TABLE(spi, max7301_id);
     77
     78static struct spi_driver max7301_driver = {
     79	.driver = {
     80		.name = "max7301",
     81	},
     82	.probe = max7301_probe,
     83	.remove = max7301_remove,
     84	.id_table = max7301_id,
     85};
     86
     87static int __init max7301_init(void)
     88{
     89	return spi_register_driver(&max7301_driver);
     90}
     91/* register after spi postcore initcall and before
     92 * subsys initcalls that may rely on these GPIOs
     93 */
     94subsys_initcall(max7301_init);
     95
     96static void __exit max7301_exit(void)
     97{
     98	spi_unregister_driver(&max7301_driver);
     99}
    100module_exit(max7301_exit);
    101
    102MODULE_AUTHOR("Juergen Beisert, Wolfram Sang");
    103MODULE_LICENSE("GPL v2");
    104MODULE_DESCRIPTION("MAX7301 GPIO-Expander");