1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
|
/*
* Xtensa xtfpga SPI controller driver
*
* Copyright (c) 2014 Cadence Design Systems Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_bitbang.h>
#define XTFPGA_SPI_NAME "xtfpga_spi"
#define XTFPGA_SPI_START 0x0
#define XTFPGA_SPI_BUSY 0x4
#define XTFPGA_SPI_DATA 0x8
#define BUSY_WAIT_US 100
struct xtfpga_spi {
struct spi_bitbang bitbang;
void __iomem *regs;
u32 data;
unsigned data_sz;
};
static inline void xtfpga_spi_write32(const struct xtfpga_spi *spi,
unsigned addr, u32 val)
{
iowrite32(val, spi->regs + addr);
}
static inline unsigned int xtfpga_spi_read32(const struct xtfpga_spi *spi,
unsigned addr)
{
return ioread32(spi->regs + addr);
}
static inline void xtfpga_spi_wait_busy(struct xtfpga_spi *xspi)
{
unsigned i;
for (i = 0; xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY) &&
i < BUSY_WAIT_US; ++i)
udelay(1);
WARN_ON_ONCE(i == BUSY_WAIT_US);
}
static u32 xtfpga_spi_txrx_word(struct spi_device *spi, unsigned nsecs,
u32 v, u8 bits)
{
struct xtfpga_spi *xspi = spi_master_get_devdata(spi->master);
xspi->data = (xspi->data << bits) | (v & GENMASK(bits - 1, 0));
xspi->data_sz += bits;
if (xspi->data_sz >= 16) {
xtfpga_spi_write32(xspi, XTFPGA_SPI_DATA,
xspi->data >> (xspi->data_sz - 16));
xspi->data_sz -= 16;
xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 1);
xtfpga_spi_wait_busy(xspi);
xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0);
}
return 0;
}
static void xtfpga_spi_chipselect(struct spi_device *spi, int is_on)
{
struct xtfpga_spi *xspi = spi_master_get_devdata(spi->master);
WARN_ON(xspi->data_sz != 0);
xspi->data_sz = 0;
}
static int xtfpga_spi_probe(struct platform_device *pdev)
{
struct xtfpga_spi *xspi;
struct resource *mem;
int ret;
struct spi_master *master;
master = spi_alloc_master(&pdev->dev, sizeof(struct xtfpga_spi));
if (!master)
return -ENOMEM;
master->flags = SPI_MASTER_NO_RX;
master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 16);
master->bus_num = pdev->dev.id;
master->dev.of_node = pdev->dev.of_node;
xspi = spi_master_get_devdata(master);
xspi->bitbang.master = master;
xspi->bitbang.chipselect = xtfpga_spi_chipselect;
xspi->bitbang.txrx_word[SPI_MODE_0] = xtfpga_spi_txrx_word;
mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!mem) {
dev_err(&pdev->dev, "No memory resource\n");
ret = -ENODEV;
goto err;
}
xspi->regs = devm_ioremap_resource(&pdev->dev, mem);
if (IS_ERR(xspi->regs)) {
ret = PTR_ERR(xspi->regs);
goto err;
}
xtfpga_spi_write32(xspi, XTFPGA_SPI_START, 0);
usleep_range(1000, 2000);
if (xtfpga_spi_read32(xspi, XTFPGA_SPI_BUSY)) {
dev_err(&pdev->dev, "Device stuck in busy state\n");
ret = -EBUSY;
goto err;
}
ret = spi_bitbang_start(&xspi->bitbang);
if (ret < 0) {
dev_err(&pdev->dev, "spi_bitbang_start failed\n");
goto err;
}
platform_set_drvdata(pdev, master);
return 0;
err:
spi_master_put(master);
return ret;
}
static int xtfpga_spi_remove(struct platform_device *pdev)
{
struct spi_master *master = platform_get_drvdata(pdev);
struct xtfpga_spi *xspi = spi_master_get_devdata(master);
spi_bitbang_stop(&xspi->bitbang);
spi_master_put(master);
return 0;
}
MODULE_ALIAS("platform:" XTFPGA_SPI_NAME);
#ifdef CONFIG_OF
static const struct of_device_id xtfpga_spi_of_match[] = {
{ .compatible = "cdns,xtfpga-spi", },
{}
};
MODULE_DEVICE_TABLE(of, xtfpga_spi_of_match);
#endif
static struct platform_driver xtfpga_spi_driver = {
.probe = xtfpga_spi_probe,
.remove = xtfpga_spi_remove,
.driver = {
.name = XTFPGA_SPI_NAME,
.owner = THIS_MODULE,
.of_match_table = of_match_ptr(xtfpga_spi_of_match),
},
};
module_platform_driver(xtfpga_spi_driver);
MODULE_AUTHOR("Max Filippov <jcmvbkbc@gmail.com>");
MODULE_DESCRIPTION("xtensa xtfpga SPI driver");
MODULE_LICENSE("GPL");
|
