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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bma400_spi.c (3033B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * SPI IIO driver for Bosch BMA400 triaxial acceleration sensor.
      4 *
      5 * Copyright 2020 Dan Robertson <dan@dlrobertson.com>
      6 *
      7 */
      8#include <linux/bits.h>
      9#include <linux/init.h>
     10#include <linux/mod_devicetable.h>
     11#include <linux/module.h>
     12#include <linux/regmap.h>
     13#include <linux/spi/spi.h>
     14
     15#include "bma400.h"
     16
     17#define BMA400_MAX_SPI_READ 2
     18#define BMA400_SPI_READ_BUFFER_SIZE (BMA400_MAX_SPI_READ + 1)
     19
     20static int bma400_regmap_spi_read(void *context,
     21				  const void *reg, size_t reg_size,
     22				  void *val, size_t val_size)
     23{
     24	struct device *dev = context;
     25	struct spi_device *spi = to_spi_device(dev);
     26	u8 result[BMA400_SPI_READ_BUFFER_SIZE];
     27	ssize_t status;
     28
     29	if (val_size > BMA400_MAX_SPI_READ)
     30		return -EINVAL;
     31
     32	status = spi_write_then_read(spi, reg, 1, result, val_size + 1);
     33	if (status)
     34		return status;
     35
     36	/*
     37	 * From the BMA400 datasheet:
     38	 *
     39	 * > For a basic read operation two bytes have to be read and the first
     40	 * > has to be dropped and the second byte must be interpreted.
     41	 */
     42	memcpy(val, result + 1, val_size);
     43
     44	return 0;
     45}
     46
     47static int bma400_regmap_spi_write(void *context, const void *data,
     48				   size_t count)
     49{
     50	struct device *dev = context;
     51	struct spi_device *spi = to_spi_device(dev);
     52
     53	return spi_write(spi, data, count);
     54}
     55
     56static struct regmap_bus bma400_regmap_bus = {
     57	.read = bma400_regmap_spi_read,
     58	.write = bma400_regmap_spi_write,
     59	.read_flag_mask = BIT(7),
     60	.max_raw_read = BMA400_MAX_SPI_READ,
     61};
     62
     63static int bma400_spi_probe(struct spi_device *spi)
     64{
     65	const struct spi_device_id *id = spi_get_device_id(spi);
     66	struct regmap *regmap;
     67	unsigned int val;
     68	int ret;
     69
     70	regmap = devm_regmap_init(&spi->dev, &bma400_regmap_bus,
     71				  &spi->dev, &bma400_regmap_config);
     72	if (IS_ERR(regmap)) {
     73		dev_err(&spi->dev, "failed to create regmap\n");
     74		return PTR_ERR(regmap);
     75	}
     76
     77	/*
     78	 * Per the bma400 datasheet, the first SPI read may
     79	 * return garbage. As the datasheet recommends, the
     80	 * chip ID register will be read here and checked
     81	 * again in the following probe.
     82	 */
     83	ret = regmap_read(regmap, BMA400_CHIP_ID_REG, &val);
     84	if (ret)
     85		dev_err(&spi->dev, "Failed to read chip id register\n");
     86
     87	return bma400_probe(&spi->dev, regmap, id->name);
     88}
     89
     90static void bma400_spi_remove(struct spi_device *spi)
     91{
     92	bma400_remove(&spi->dev);
     93}
     94
     95static const struct spi_device_id bma400_spi_ids[] = {
     96	{ "bma400", 0 },
     97	{ }
     98};
     99MODULE_DEVICE_TABLE(spi, bma400_spi_ids);
    100
    101static const struct of_device_id bma400_of_spi_match[] = {
    102	{ .compatible = "bosch,bma400" },
    103	{ }
    104};
    105MODULE_DEVICE_TABLE(of, bma400_of_spi_match);
    106
    107static struct spi_driver bma400_spi_driver = {
    108	.driver = {
    109		.name = "bma400",
    110		.of_match_table = bma400_of_spi_match,
    111	},
    112	.probe    = bma400_spi_probe,
    113	.remove   = bma400_spi_remove,
    114	.id_table = bma400_spi_ids,
    115};
    116
    117module_spi_driver(bma400_spi_driver);
    118MODULE_AUTHOR("Dan Robertson <dan@dlrobertson.com>");
    119MODULE_DESCRIPTION("Bosch BMA400 triaxial acceleration sensor (SPI)");
    120MODULE_LICENSE("GPL");
    121MODULE_IMPORT_NS(IIO_BMA400);