tjh.dev
Linux kernel mirror (for testing)
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linux
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");