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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spi-xtensa-xtfpga.c (3823B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Xtensa xtfpga SPI controller driver
      4 *
      5 * Copyright (c) 2014 Cadence Design Systems Inc.
      6 */
      7
      8#include <linux/delay.h>
      9#include <linux/io.h>
     10#include <linux/module.h>
     11#include <linux/of.h>
     12#include <linux/platform_device.h>
     13#include <linux/spi/spi.h>
     14#include <linux/spi/spi_bitbang.h>
     15
     16#define XTFPGA_SPI_NAME "xtfpga_spi"
     17
     18#define XTFPGA_SPI_START	0x0
     19#define XTFPGA_SPI_BUSY		0x4
     20#define XTFPGA_SPI_DATA		0x8
     21
     22#define BUSY_WAIT_US		100
     23
     24struct xtfpga_spi {
     25	struct spi_bitbang bitbang;
     26	void __iomem *regs;
     27	u32 data;
     28	unsigned data_sz;
     29};
     30
     31static inline void xtfpga_spi_write32(const struct xtfpga_spi *spi,
     32				      unsigned addr, u32 val)
     33{
     34	__raw_writel(val, spi->regs + addr);
     35}
     36
     37static inline unsigned int xtfpga_spi_read32(const struct xtfpga_spi *spi,
     38					     unsigned addr)
     39{
     40	return __raw_readl(spi->regs + addr);
     41}
     42
     43static inline void xtfpga_spi_wait_busy(struct xtfpga_spi *xspi)
     44{
     45	unsigned i;
     46
     47	for (i = 0; xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY) &&
     48	     i < BUSY_WAIT_US; ++i)
     49		udelay(1);
     50	WARN_ON_ONCE(i == BUSY_WAIT_US);
     51}
     52
     53static u32 xtfpga_spi_txrx_word(struct spi_device *spi, unsigned nsecs,
     54				u32 v, u8 bits, unsigned flags)
     55{
     56	struct xtfpga_spi *xspi = spi_master_get_devdata(spi->master);
     57
     58	xspi->data = (xspi->data << bits) | (v & GENMASK(bits - 1, 0));
     59	xspi->data_sz += bits;
     60	if (xspi->data_sz >= 16) {
     61		xtfpga_spi_write32(xspi, XTFPGA_SPI_DATA,
     62				   xspi->data >> (xspi->data_sz - 16));
     63		xspi->data_sz -= 16;
     64		xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 1);
     65		xtfpga_spi_wait_busy(xspi);
     66		xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0);
     67	}
     68
     69	return 0;
     70}
     71
     72static void xtfpga_spi_chipselect(struct spi_device *spi, int is_on)
     73{
     74	struct xtfpga_spi *xspi = spi_master_get_devdata(spi->master);
     75
     76	WARN_ON(xspi->data_sz != 0);
     77	xspi->data_sz = 0;
     78}
     79
     80static int xtfpga_spi_probe(struct platform_device *pdev)
     81{
     82	struct xtfpga_spi *xspi;
     83	int ret;
     84	struct spi_master *master;
     85
     86	master = spi_alloc_master(&pdev->dev, sizeof(struct xtfpga_spi));
     87	if (!master)
     88		return -ENOMEM;
     89
     90	master->flags = SPI_MASTER_NO_RX;
     91	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16);
     92	master->bus_num = pdev->dev.id;
     93	master->dev.of_node = pdev->dev.of_node;
     94
     95	xspi = spi_master_get_devdata(master);
     96	xspi->bitbang.master = master;
     97	xspi->bitbang.chipselect = xtfpga_spi_chipselect;
     98	xspi->bitbang.txrx_word[SPI_MODE_0] = xtfpga_spi_txrx_word;
     99	xspi->regs = devm_platform_ioremap_resource(pdev, 0);
    100	if (IS_ERR(xspi->regs)) {
    101		ret = PTR_ERR(xspi->regs);
    102		goto err;
    103	}
    104
    105	xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0);
    106	usleep_range(1000, 2000);
    107	if (xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY)) {
    108		dev_err(&pdev->dev, "Device stuck in busy state\n");
    109		ret = -EBUSY;
    110		goto err;
    111	}
    112
    113	ret = spi_bitbang_start(&xspi->bitbang);
    114	if (ret < 0) {
    115		dev_err(&pdev->dev, "spi_bitbang_start failed\n");
    116		goto err;
    117	}
    118
    119	platform_set_drvdata(pdev, master);
    120	return 0;
    121err:
    122	spi_master_put(master);
    123	return ret;
    124}
    125
    126static int xtfpga_spi_remove(struct platform_device *pdev)
    127{
    128	struct spi_master *master = platform_get_drvdata(pdev);
    129	struct xtfpga_spi *xspi = spi_master_get_devdata(master);
    130
    131	spi_bitbang_stop(&xspi->bitbang);
    132	spi_master_put(master);
    133
    134	return 0;
    135}
    136
    137MODULE_ALIAS("platform:" XTFPGA_SPI_NAME);
    138
    139#ifdef CONFIG_OF
    140static const struct of_device_id xtfpga_spi_of_match[] = {
    141	{ .compatible = "cdns,xtfpga-spi", },
    142	{}
    143};
    144MODULE_DEVICE_TABLE(of, xtfpga_spi_of_match);
    145#endif
    146
    147static struct platform_driver xtfpga_spi_driver = {
    148	.probe = xtfpga_spi_probe,
    149	.remove = xtfpga_spi_remove,
    150	.driver = {
    151		.name = XTFPGA_SPI_NAME,
    152		.of_match_table = of_match_ptr(xtfpga_spi_of_match),
    153	},
    154};
    155module_platform_driver(xtfpga_spi_driver);
    156
    157MODULE_AUTHOR("Max Filippov <jcmvbkbc@gmail.com>");
    158MODULE_DESCRIPTION("xtensa xtfpga SPI driver");
    159MODULE_LICENSE("GPL");