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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max5487.c (3856B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * max5487.c - Support for MAX5487, MAX5488, MAX5489 digital potentiometers
      4 *
      5 * Copyright (C) 2016 Cristina-Gabriela Moraru <cristina.moraru09@gmail.com>
      6 */
      7#include <linux/module.h>
      8#include <linux/spi/spi.h>
      9#include <linux/acpi.h>
     10
     11#include <linux/iio/sysfs.h>
     12#include <linux/iio/iio.h>
     13
     14#define MAX5487_WRITE_WIPER_A	(0x01 << 8)
     15#define MAX5487_WRITE_WIPER_B	(0x02 << 8)
     16
     17/* copy both wiper regs to NV regs */
     18#define MAX5487_COPY_AB_TO_NV	(0x23 << 8)
     19/* copy both NV regs to wiper regs */
     20#define MAX5487_COPY_NV_TO_AB	(0x33 << 8)
     21
     22#define MAX5487_MAX_POS		255
     23
     24struct max5487_data {
     25	struct spi_device *spi;
     26	int kohms;
     27};
     28
     29#define MAX5487_CHANNEL(ch, addr) {				\
     30	.type = IIO_RESISTANCE,					\
     31	.indexed = 1,						\
     32	.output = 1,						\
     33	.channel = ch,						\
     34	.address = addr,					\
     35	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
     36	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
     37}
     38
     39static const struct iio_chan_spec max5487_channels[] = {
     40	MAX5487_CHANNEL(0, MAX5487_WRITE_WIPER_A),
     41	MAX5487_CHANNEL(1, MAX5487_WRITE_WIPER_B),
     42};
     43
     44static int max5487_write_cmd(struct spi_device *spi, u16 cmd)
     45{
     46	return spi_write(spi, (const void *) &cmd, sizeof(u16));
     47}
     48
     49static int max5487_read_raw(struct iio_dev *indio_dev,
     50			    struct iio_chan_spec const *chan,
     51			    int *val, int *val2, long mask)
     52{
     53	struct max5487_data *data = iio_priv(indio_dev);
     54
     55	if (mask != IIO_CHAN_INFO_SCALE)
     56		return -EINVAL;
     57
     58	*val = 1000 * data->kohms;
     59	*val2 = MAX5487_MAX_POS;
     60
     61	return IIO_VAL_FRACTIONAL;
     62}
     63
     64static int max5487_write_raw(struct iio_dev *indio_dev,
     65			     struct iio_chan_spec const *chan,
     66			     int val, int val2, long mask)
     67{
     68	struct max5487_data *data = iio_priv(indio_dev);
     69
     70	if (mask != IIO_CHAN_INFO_RAW)
     71		return -EINVAL;
     72
     73	if (val < 0 || val > MAX5487_MAX_POS)
     74		return -EINVAL;
     75
     76	return max5487_write_cmd(data->spi, chan->address | val);
     77}
     78
     79static const struct iio_info max5487_info = {
     80	.read_raw = max5487_read_raw,
     81	.write_raw = max5487_write_raw,
     82};
     83
     84static int max5487_spi_probe(struct spi_device *spi)
     85{
     86	struct iio_dev *indio_dev;
     87	struct max5487_data *data;
     88	const struct spi_device_id *id = spi_get_device_id(spi);
     89	int ret;
     90
     91	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data));
     92	if (!indio_dev)
     93		return -ENOMEM;
     94
     95	spi_set_drvdata(spi, indio_dev);
     96	data = iio_priv(indio_dev);
     97
     98	data->spi = spi;
     99	data->kohms = id->driver_data;
    100
    101	indio_dev->info = &max5487_info;
    102	indio_dev->name = id->name;
    103	indio_dev->modes = INDIO_DIRECT_MODE;
    104	indio_dev->channels = max5487_channels;
    105	indio_dev->num_channels = ARRAY_SIZE(max5487_channels);
    106
    107	/* restore both wiper regs from NV regs */
    108	ret = max5487_write_cmd(data->spi, MAX5487_COPY_NV_TO_AB);
    109	if (ret < 0)
    110		return ret;
    111
    112	return iio_device_register(indio_dev);
    113}
    114
    115static void max5487_spi_remove(struct spi_device *spi)
    116{
    117	struct iio_dev *indio_dev = spi_get_drvdata(spi);
    118	int ret;
    119
    120	iio_device_unregister(indio_dev);
    121
    122	/* save both wiper regs to NV regs */
    123	ret = max5487_write_cmd(spi, MAX5487_COPY_AB_TO_NV);
    124	if (ret)
    125		dev_warn(&spi->dev, "Failed to save wiper regs to NV regs\n");
    126}
    127
    128static const struct spi_device_id max5487_id[] = {
    129	{ "MAX5487", 10 },
    130	{ "MAX5488", 50 },
    131	{ "MAX5489", 100 },
    132	{ }
    133};
    134MODULE_DEVICE_TABLE(spi, max5487_id);
    135
    136static const struct acpi_device_id max5487_acpi_match[] = {
    137	{ "MAX5487", 10 },
    138	{ "MAX5488", 50 },
    139	{ "MAX5489", 100 },
    140	{ },
    141};
    142MODULE_DEVICE_TABLE(acpi, max5487_acpi_match);
    143
    144static struct spi_driver max5487_driver = {
    145	.driver = {
    146		.name = "max5487",
    147		.acpi_match_table = ACPI_PTR(max5487_acpi_match),
    148	},
    149	.id_table = max5487_id,
    150	.probe = max5487_spi_probe,
    151	.remove = max5487_spi_remove
    152};
    153module_spi_driver(max5487_driver);
    154
    155MODULE_AUTHOR("Cristina-Gabriela Moraru <cristina.moraru09@gmail.com>");
    156MODULE_DESCRIPTION("max5487 SPI driver");
    157MODULE_LICENSE("GPL v2");