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
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
|
/*
* SPI controller driver for the Mikrotik RB4xx boards
*
* Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org>
* Copyright (C) 2015 Bert Vermeulen <bert@biot.com>
*
* This file was based on the patches for Linux 2.6.27.39 published by
* MikroTik for their RouterBoard 4xx series devices.
*
* 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/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/spi/spi.h>
#include <asm/mach-ath79/ar71xx_regs.h>
struct rb4xx_spi {
void __iomem *base;
struct clk *clk;
};
static inline u32 rb4xx_read(struct rb4xx_spi *rbspi, u32 reg)
{
return __raw_readl(rbspi->base + reg);
}
static inline void rb4xx_write(struct rb4xx_spi *rbspi, u32 reg, u32 value)
{
__raw_writel(value, rbspi->base + reg);
}
static inline void do_spi_clk(struct rb4xx_spi *rbspi, u32 spi_ioc, int value)
{
u32 regval;
regval = spi_ioc;
if (value & BIT(0))
regval |= AR71XX_SPI_IOC_DO;
rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval);
rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval | AR71XX_SPI_IOC_CLK);
}
static void do_spi_byte(struct rb4xx_spi *rbspi, u32 spi_ioc, u8 byte)
{
int i;
for (i = 7; i >= 0; i--)
do_spi_clk(rbspi, spi_ioc, byte >> i);
}
/* The CS2 pin is used to clock in a second bit per clock cycle. */
static inline void do_spi_clk_two(struct rb4xx_spi *rbspi, u32 spi_ioc,
u8 value)
{
u32 regval;
regval = spi_ioc;
if (value & BIT(1))
regval |= AR71XX_SPI_IOC_DO;
if (value & BIT(0))
regval |= AR71XX_SPI_IOC_CS2;
rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval);
rb4xx_write(rbspi, AR71XX_SPI_REG_IOC, regval | AR71XX_SPI_IOC_CLK);
}
/* Two bits at a time, msb first */
static void do_spi_byte_two(struct rb4xx_spi *rbspi, u32 spi_ioc, u8 byte)
{
do_spi_clk_two(rbspi, spi_ioc, byte >> 6);
do_spi_clk_two(rbspi, spi_ioc, byte >> 4);
do_spi_clk_two(rbspi, spi_ioc, byte >> 2);
do_spi_clk_two(rbspi, spi_ioc, byte >> 0);
}
static void rb4xx_set_cs(struct spi_device *spi, bool enable)
{
struct rb4xx_spi *rbspi = spi_master_get_devdata(spi->master);
/*
* Setting CS is done along with bitbanging the actual values,
* since it's all on the same hardware register. However the
* CPLD needs CS deselected after every command.
*/
if (!enable)
rb4xx_write(rbspi, AR71XX_SPI_REG_IOC,
AR71XX_SPI_IOC_CS0 | AR71XX_SPI_IOC_CS1);
}
static int rb4xx_transfer_one(struct spi_master *master,
struct spi_device *spi, struct spi_transfer *t)
{
struct rb4xx_spi *rbspi = spi_master_get_devdata(master);
int i;
u32 spi_ioc;
u8 *rx_buf;
const u8 *tx_buf;
/*
* Prime the SPI register with the SPI device selected. The m25p80 boot
* flash and CPLD share the CS0 pin. This works because the CPLD's
* command set was designed to almost not clash with that of the
* boot flash.
*/
if (spi->chip_select == 2)
/* MMC */
spi_ioc = AR71XX_SPI_IOC_CS0;
else
/* Boot flash and CPLD */
spi_ioc = AR71XX_SPI_IOC_CS1;
tx_buf = t->tx_buf;
rx_buf = t->rx_buf;
for (i = 0; i < t->len; ++i) {
if (t->tx_nbits == SPI_NBITS_DUAL)
/* CPLD can use two-wire transfers */
do_spi_byte_two(rbspi, spi_ioc, tx_buf[i]);
else
do_spi_byte(rbspi, spi_ioc, tx_buf[i]);
if (!rx_buf)
continue;
rx_buf[i] = rb4xx_read(rbspi, AR71XX_SPI_REG_RDS);
}
spi_finalize_current_transfer(master);
return 0;
}
static int rb4xx_spi_probe(struct platform_device *pdev)
{
struct spi_master *master;
struct clk *ahb_clk;
struct rb4xx_spi *rbspi;
struct resource *r;
int err;
void __iomem *spi_base;
r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
spi_base = devm_ioremap_resource(&pdev->dev, r);
if (!spi_base)
return PTR_ERR(spi_base);
master = spi_alloc_master(&pdev->dev, sizeof(*rbspi));
if (!master)
return -ENOMEM;
ahb_clk = devm_clk_get(&pdev->dev, "ahb");
if (IS_ERR(ahb_clk))
return PTR_ERR(ahb_clk);
master->bus_num = 0;
master->num_chipselect = 3;
master->mode_bits = SPI_TX_DUAL;
master->bits_per_word_mask = BIT(7);
master->flags = SPI_MASTER_MUST_TX;
master->transfer_one = rb4xx_transfer_one;
master->set_cs = rb4xx_set_cs;
err = devm_spi_register_master(&pdev->dev, master);
if (err) {
dev_err(&pdev->dev, "failed to register SPI master\n");
return err;
}
err = clk_prepare_enable(ahb_clk);
if (err)
return err;
rbspi = spi_master_get_devdata(master);
rbspi->base = spi_base;
rbspi->clk = ahb_clk;
platform_set_drvdata(pdev, rbspi);
/* Enable SPI */
rb4xx_write(rbspi, AR71XX_SPI_REG_FS, AR71XX_SPI_FS_GPIO);
return 0;
}
static int rb4xx_spi_remove(struct platform_device *pdev)
{
struct rb4xx_spi *rbspi = platform_get_drvdata(pdev);
clk_disable_unprepare(rbspi->clk);
return 0;
}
static struct platform_driver rb4xx_spi_drv = {
.probe = rb4xx_spi_probe,
.remove = rb4xx_spi_remove,
.driver = {
.name = "rb4xx-spi",
},
};
module_platform_driver(rb4xx_spi_drv);
MODULE_DESCRIPTION("Mikrotik RB4xx SPI controller driver");
MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
MODULE_AUTHOR("Bert Vermeulen <bert@biot.com>");
MODULE_LICENSE("GPL v2");
|
