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-mc33880.c (3494B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * MC33880 high-side/low-side switch GPIO driver
      4 * Copyright (c) 2009 Intel Corporation
      5 */
      6
      7/* Supports:
      8 * Freescale MC33880 high-side/low-side switch
      9 */
     10
     11#include <linux/init.h>
     12#include <linux/mutex.h>
     13#include <linux/spi/spi.h>
     14#include <linux/spi/mc33880.h>
     15#include <linux/gpio/driver.h>
     16#include <linux/slab.h>
     17#include <linux/module.h>
     18
     19#define DRIVER_NAME "mc33880"
     20
     21/*
     22 * Pin configurations, see MAX7301 datasheet page 6
     23 */
     24#define PIN_CONFIG_MASK 0x03
     25#define PIN_CONFIG_IN_PULLUP 0x03
     26#define PIN_CONFIG_IN_WO_PULLUP 0x02
     27#define PIN_CONFIG_OUT 0x01
     28
     29#define PIN_NUMBER 8
     30
     31
     32/*
     33 * Some registers must be read back to modify.
     34 * To save time we cache them here in memory
     35 */
     36struct mc33880 {
     37	struct mutex	lock;	/* protect from simultaneous accesses */
     38	u8		port_config;
     39	struct gpio_chip chip;
     40	struct spi_device *spi;
     41};
     42
     43static int mc33880_write_config(struct mc33880 *mc)
     44{
     45	return spi_write(mc->spi, &mc->port_config, sizeof(mc->port_config));
     46}
     47
     48
     49static int __mc33880_set(struct mc33880 *mc, unsigned offset, int value)
     50{
     51	if (value)
     52		mc->port_config |= 1 << offset;
     53	else
     54		mc->port_config &= ~(1 << offset);
     55
     56	return mc33880_write_config(mc);
     57}
     58
     59
     60static void mc33880_set(struct gpio_chip *chip, unsigned offset, int value)
     61{
     62	struct mc33880 *mc = gpiochip_get_data(chip);
     63
     64	mutex_lock(&mc->lock);
     65
     66	__mc33880_set(mc, offset, value);
     67
     68	mutex_unlock(&mc->lock);
     69}
     70
     71static int mc33880_probe(struct spi_device *spi)
     72{
     73	struct mc33880 *mc;
     74	struct mc33880_platform_data *pdata;
     75	int ret;
     76
     77	pdata = dev_get_platdata(&spi->dev);
     78	if (!pdata || !pdata->base) {
     79		dev_dbg(&spi->dev, "incorrect or missing platform data\n");
     80		return -EINVAL;
     81	}
     82
     83	/*
     84	 * bits_per_word cannot be configured in platform data
     85	 */
     86	spi->bits_per_word = 8;
     87
     88	ret = spi_setup(spi);
     89	if (ret < 0)
     90		return ret;
     91
     92	mc = devm_kzalloc(&spi->dev, sizeof(struct mc33880), GFP_KERNEL);
     93	if (!mc)
     94		return -ENOMEM;
     95
     96	mutex_init(&mc->lock);
     97
     98	spi_set_drvdata(spi, mc);
     99
    100	mc->spi = spi;
    101
    102	mc->chip.label = DRIVER_NAME,
    103	mc->chip.set = mc33880_set;
    104	mc->chip.base = pdata->base;
    105	mc->chip.ngpio = PIN_NUMBER;
    106	mc->chip.can_sleep = true;
    107	mc->chip.parent = &spi->dev;
    108	mc->chip.owner = THIS_MODULE;
    109
    110	mc->port_config = 0x00;
    111	/* write twice, because during initialisation the first setting
    112	 * is just for testing SPI communication, and the second is the
    113	 * "real" configuration
    114	 */
    115	ret = mc33880_write_config(mc);
    116	mc->port_config = 0x00;
    117	if (!ret)
    118		ret = mc33880_write_config(mc);
    119
    120	if (ret) {
    121		dev_err(&spi->dev, "Failed writing to " DRIVER_NAME ": %d\n",
    122			ret);
    123		goto exit_destroy;
    124	}
    125
    126	ret = gpiochip_add_data(&mc->chip, mc);
    127	if (ret)
    128		goto exit_destroy;
    129
    130	return ret;
    131
    132exit_destroy:
    133	mutex_destroy(&mc->lock);
    134	return ret;
    135}
    136
    137static void mc33880_remove(struct spi_device *spi)
    138{
    139	struct mc33880 *mc;
    140
    141	mc = spi_get_drvdata(spi);
    142
    143	gpiochip_remove(&mc->chip);
    144	mutex_destroy(&mc->lock);
    145}
    146
    147static struct spi_driver mc33880_driver = {
    148	.driver = {
    149		.name		= DRIVER_NAME,
    150	},
    151	.probe		= mc33880_probe,
    152	.remove		= mc33880_remove,
    153};
    154
    155static int __init mc33880_init(void)
    156{
    157	return spi_register_driver(&mc33880_driver);
    158}
    159/* register after spi postcore initcall and before
    160 * subsys initcalls that may rely on these GPIOs
    161 */
    162subsys_initcall(mc33880_init);
    163
    164static void __exit mc33880_exit(void)
    165{
    166	spi_unregister_driver(&mc33880_driver);
    167}
    168module_exit(mc33880_exit);
    169
    170MODULE_AUTHOR("Mocean Laboratories <info@mocean-labs.com>");
    171MODULE_LICENSE("GPL v2");
    172