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_controller_get_devdata(spi->controller);
 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_controller_get_devdata(spi->controller);
 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_controller *host;
 85
 86	host = devm_spi_alloc_host(&pdev->dev, sizeof(struct xtfpga_spi));
 87	if (!host)
 88		return -ENOMEM;
 89
 90	host->flags = SPI_CONTROLLER_NO_RX;
 91	host->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16);
 92	host->bus_num = pdev->dev.id;
 93	host->dev.of_node = pdev->dev.of_node;
 94
 95	xspi = spi_controller_get_devdata(host);
 96	xspi->bitbang.ctlr = host;
 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		return PTR_ERR(xspi->regs);
102
103	xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0);
104	usleep_range(1000, 2000);
105	if (xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY)) {
106		dev_err(&pdev->dev, "Device stuck in busy state\n");
107		return -EBUSY;
108	}
109
110	ret = spi_bitbang_start(&xspi->bitbang);
111	if (ret < 0) {
112		dev_err(&pdev->dev, "spi_bitbang_start failed\n");
113		return ret;
114	}
115
116	platform_set_drvdata(pdev, host);
117	return 0;
118}
119
120static void xtfpga_spi_remove(struct platform_device *pdev)
121{
122	struct spi_controller *host = platform_get_drvdata(pdev);
123	struct xtfpga_spi *xspi = spi_controller_get_devdata(host);
124
125	spi_bitbang_stop(&xspi->bitbang);
126	spi_controller_put(host);
127}
128
129MODULE_ALIAS("platform:" XTFPGA_SPI_NAME);
130
131#ifdef CONFIG_OF
132static const struct of_device_id xtfpga_spi_of_match[] = {
133	{ .compatible = "cdns,xtfpga-spi", },
134	{}
135};
136MODULE_DEVICE_TABLE(of, xtfpga_spi_of_match);
137#endif
138
139static struct platform_driver xtfpga_spi_driver = {
140	.probe = xtfpga_spi_probe,
141	.remove_new = xtfpga_spi_remove,
142	.driver = {
143		.name = XTFPGA_SPI_NAME,
144		.of_match_table = of_match_ptr(xtfpga_spi_of_match),
145	},
146};
147module_platform_driver(xtfpga_spi_driver);
148
149MODULE_AUTHOR("Max Filippov <jcmvbkbc@gmail.com>");
150MODULE_DESCRIPTION("xtensa xtfpga SPI driver");
151MODULE_LICENSE("GPL");