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");
160