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	struct resource *mem;
 84	int ret;
 85	struct spi_master *master;
 86
 87	master = spi_alloc_master(&pdev->dev, sizeof(struct xtfpga_spi));
 88	if (!master)
 89		return -ENOMEM;
 90
 91	master->flags = SPI_MASTER_NO_RX;
 92	master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16);
 93	master->bus_num = pdev->dev.id;
 94	master->dev.of_node = pdev->dev.of_node;
 95
 96	xspi = spi_master_get_devdata(master);
 97	xspi->bitbang.master = master;
 98	xspi->bitbang.chipselect = xtfpga_spi_chipselect;
 99	xspi->bitbang.txrx_word[SPI_MODE_0] = xtfpga_spi_txrx_word;
100
101	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
102	if (!mem) {
103		dev_err(&pdev->dev, "No memory resource\n");
104		ret = -ENODEV;
105		goto err;
106	}
107	xspi->regs = devm_ioremap_resource(&pdev->dev, mem);
108	if (IS_ERR(xspi->regs)) {
109		ret = PTR_ERR(xspi->regs);
110		goto err;
111	}
112
113	xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0);
114	usleep_range(1000, 2000);
115	if (xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY)) {
116		dev_err(&pdev->dev, "Device stuck in busy state\n");
117		ret = -EBUSY;
118		goto err;
119	}
120
121	ret = spi_bitbang_start(&xspi->bitbang);
122	if (ret < 0) {
123		dev_err(&pdev->dev, "spi_bitbang_start failed\n");
124		goto err;
125	}
126
127	platform_set_drvdata(pdev, master);
128	return 0;
129err:
130	spi_master_put(master);
131	return ret;
132}
133
134static int xtfpga_spi_remove(struct platform_device *pdev)
135{
136	struct spi_master *master = platform_get_drvdata(pdev);
137	struct xtfpga_spi *xspi = spi_master_get_devdata(master);
138
139	spi_bitbang_stop(&xspi->bitbang);
140	spi_master_put(master);
141
142	return 0;
143}
144
145MODULE_ALIAS("platform:" XTFPGA_SPI_NAME);
146
147#ifdef CONFIG_OF
148static const struct of_device_id xtfpga_spi_of_match[] = {
149	{ .compatible = "cdns,xtfpga-spi", },
150	{}
151};
152MODULE_DEVICE_TABLE(of, xtfpga_spi_of_match);
153#endif
154
155static struct platform_driver xtfpga_spi_driver = {
156	.probe = xtfpga_spi_probe,
157	.remove = xtfpga_spi_remove,
158	.driver = {
159		.name = XTFPGA_SPI_NAME,
160		.of_match_table = of_match_ptr(xtfpga_spi_of_match),
161	},
162};
163module_platform_driver(xtfpga_spi_driver);
164
165MODULE_AUTHOR("Max Filippov <jcmvbkbc@gmail.com>");
166MODULE_DESCRIPTION("xtensa xtfpga SPI driver");
167MODULE_LICENSE("GPL");