2 * Custom GPIO-based SPI driver
4 * Copyright (C) 2013 Marco Burato <zmaster.adsl@gmail.com>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
10 * Based on i2c-gpio-custom by:
11 * Copyright (C) 2007-2008 Gabor Juhos <juhosg@openwrt.org>
12 * ---------------------------------------------------------------------------
14 * The behaviour of this driver can be altered by setting some parameters
15 * from the insmod command line.
17 * The following parameters are adjustable:
19 * bus0 These four arguments can be arrays of
20 * bus1 1-8 unsigned integers as follows:
22 * bus3 <id>,<sck>,<mosi>,<miso>,<mode1>,<maxfreq1>,<cs1>,...
26 * <id> ID to used as device_id for the corresponding bus (required)
27 * <sck> GPIO pin ID to be used for bus SCK (required)
28 * <mosi> GPIO pin ID to be used for bus MOSI (required*)
29 * <miso> GPIO pin ID to be used for bus MISO (required*)
30 * <modeX> Mode configuration for slave X in the bus (required)
31 * (see /include/linux/spi/spi.h)
32 * <maxfreqX> Maximum clock frequency in Hz for slave X in the bus (required)
33 * <csX> GPIO pin ID to be used for slave X CS (required**)
36 * * If a signal is not used (for example there is no MISO) you need
37 * to set the GPIO pin ID for that signal to an invalid value.
38 * ** If you only have 1 slave in the bus with no CS, you can omit the
39 * <cs1> param or set it to an invalid GPIO id to disable it. When
40 * you have 2 or more slaves, they must all have a valid CS.
42 * If this driver is built into the kernel, you can use the following kernel
43 * command line parameters, with the same values as the corresponding module
44 * parameters listed above:
46 * spi-gpio-custom.bus0
47 * spi-gpio-custom.bus1
48 * spi-gpio-custom.bus2
49 * spi-gpio-custom.bus3
52 #include <linux/kernel.h>
53 #include <linux/module.h>
54 #include <linux/init.h>
55 #include <linux/platform_device.h>
57 #include <linux/gpio.h>
58 #include <linux/spi/spi.h>
59 #include <linux/spi/spi_gpio.h>
61 #define DRV_NAME "spi-gpio-custom"
62 #define DRV_DESC "Custom GPIO-based SPI driver"
63 #define DRV_VERSION "0.1"
65 #define PFX DRV_NAME ": "
67 #define BUS_PARAM_ID 0
68 #define BUS_PARAM_SCK 1
69 #define BUS_PARAM_MOSI 2
70 #define BUS_PARAM_MISO 3
71 #define BUS_PARAM_MODE1 4
72 #define BUS_PARAM_MAXFREQ1 5
73 #define BUS_PARAM_CS1 6
75 #define BUS_SLAVE_COUNT_MAX 8
76 #define BUS_PARAM_REQUIRED 6
77 #define BUS_PARAM_PER_SLAVE 3
78 #define BUS_PARAM_COUNT (4+BUS_PARAM_PER_SLAVE*BUS_SLAVE_COUNT_MAX)
79 #define BUS_COUNT_MAX 4
81 static unsigned int bus0
[BUS_PARAM_COUNT
] __initdata
;
82 static unsigned int bus1
[BUS_PARAM_COUNT
] __initdata
;
83 static unsigned int bus2
[BUS_PARAM_COUNT
] __initdata
;
84 static unsigned int bus3
[BUS_PARAM_COUNT
] __initdata
;
86 static unsigned int bus_nump
[BUS_COUNT_MAX
] __initdata
;
88 #define BUS_PARM_DESC \
89 " config -> id,sck,mosi,miso,mode1,maxfreq1[,cs1,mode2,maxfreq2,cs2,...]"
91 module_param_array(bus0
, uint
, &bus_nump
[0], 0);
92 MODULE_PARM_DESC(bus0
, "bus0" BUS_PARM_DESC
);
93 module_param_array(bus1
, uint
, &bus_nump
[1], 0);
94 MODULE_PARM_DESC(bus1
, "bus1" BUS_PARM_DESC
);
95 module_param_array(bus2
, uint
, &bus_nump
[2], 0);
96 MODULE_PARM_DESC(bus2
, "bus2" BUS_PARM_DESC
);
97 module_param_array(bus3
, uint
, &bus_nump
[3], 0);
98 MODULE_PARM_DESC(bus3
, "bus3" BUS_PARM_DESC
);
100 static struct platform_device
*devices
[BUS_COUNT_MAX
];
101 static unsigned int nr_devices
;
103 static void spi_gpio_custom_cleanup(void)
107 for (i
= 0; i
< nr_devices
; i
++)
109 platform_device_unregister(devices
[i
]);
112 static int spi_gpio_custom_get_slave_mode(unsigned int id
,
113 unsigned int *params
,
118 param_index
= BUS_PARAM_MODE1
+slave_index
*BUS_PARAM_PER_SLAVE
;
119 if (param_index
>= bus_nump
[id
])
122 return params
[param_index
];
124 static int spi_gpio_custom_get_slave_maxfreq(unsigned int id
,
125 unsigned int *params
,
130 param_index
= BUS_PARAM_MAXFREQ1
+slave_index
*BUS_PARAM_PER_SLAVE
;
131 if (param_index
>= bus_nump
[id
])
134 return params
[param_index
];
136 static int spi_gpio_custom_get_slave_cs(unsigned int id
,
137 unsigned int *params
,
142 param_index
= BUS_PARAM_CS1
+slave_index
*BUS_PARAM_PER_SLAVE
;
143 if (param_index
>= bus_nump
[id
])
145 if (!gpio_is_valid(params
[param_index
]))
148 return params
[param_index
];
151 static int spi_gpio_custom_check_params(unsigned int id
, unsigned int *params
)
154 struct spi_master
*master
;
156 if (bus_nump
[id
] < BUS_PARAM_REQUIRED
) {
157 printk(KERN_ERR PFX
"not enough values for parameter bus%d\n",
162 if (bus_nump
[id
] > (1+BUS_PARAM_CS1
)) {
163 /* more than 1 device: check CS GPIOs */
164 for (i
= 0; i
< BUS_SLAVE_COUNT_MAX
; i
++) {
165 /* no more slaves? */
166 if (spi_gpio_custom_get_slave_mode(id
, params
, i
) < 0)
169 if (spi_gpio_custom_get_slave_cs(id
, params
, i
) < 0) {
170 printk(KERN_ERR PFX
"invalid/missing CS gpio for slave %d on bus %d\n",
171 i
, params
[BUS_PARAM_ID
]);
177 if (!gpio_is_valid(params
[BUS_PARAM_SCK
])) {
178 printk(KERN_ERR PFX
"invalid SCK gpio for bus %d\n",
179 params
[BUS_PARAM_ID
]);
183 master
= spi_busnum_to_master(params
[BUS_PARAM_ID
]);
185 spi_master_put(master
);
186 printk(KERN_ERR PFX
"bus %d already exists\n",
187 params
[BUS_PARAM_ID
]);
194 static int __init
spi_gpio_custom_add_one(unsigned int id
, unsigned int *params
)
196 struct platform_device
*pdev
;
197 struct spi_gpio_platform_data pdata
;
201 struct spi_master
*master
;
202 struct spi_device
*slave
;
203 struct spi_board_info slave_info
;
204 int mode
, maxfreq
, cs
;
210 err
= spi_gpio_custom_check_params(id
, params
);
214 /* Create BUS device node */
216 pdev
= platform_device_alloc("spi_gpio", params
[BUS_PARAM_ID
]);
223 for (i
= 0; i
< BUS_SLAVE_COUNT_MAX
; i
++) {
224 /* no more slaves? */
225 if (spi_gpio_custom_get_slave_mode(id
, params
, i
) < 0)
228 if (spi_gpio_custom_get_slave_cs(id
, params
, i
) >= 0)
233 * Even if no CS is used, spi modules expect
234 * at least 1 (unused)
239 pdata
.sck
= params
[BUS_PARAM_SCK
];
240 pdata
.mosi
= gpio_is_valid(params
[BUS_PARAM_MOSI
])
241 ? params
[BUS_PARAM_MOSI
]
243 pdata
.miso
= gpio_is_valid(params
[BUS_PARAM_MISO
])
244 ? params
[BUS_PARAM_MISO
]
246 pdata
.num_chipselect
= num_cs
;
248 err
= platform_device_add_data(pdev
, &pdata
, sizeof(pdata
));
250 platform_device_put(pdev
);
254 err
= platform_device_add(pdev
);
256 printk(KERN_ERR PFX
"platform_device_add failed with return code %d\n",
258 platform_device_put(pdev
);
262 /* Register SLAVE devices */
264 for (i
= 0; i
< BUS_SLAVE_COUNT_MAX
; i
++) {
265 mode
= spi_gpio_custom_get_slave_mode(id
, params
, i
);
266 maxfreq
= spi_gpio_custom_get_slave_maxfreq(id
, params
, i
);
267 cs
= spi_gpio_custom_get_slave_cs(id
, params
, i
);
269 /* no more slaves? */
273 memset(&slave_info
, 0, sizeof(slave_info
));
274 strcpy(slave_info
.modalias
, "spidev");
275 slave_info
.controller_data
= (void *)((cs
>= 0)
277 : SPI_GPIO_NO_CHIPSELECT
);
278 slave_info
.max_speed_hz
= maxfreq
;
279 slave_info
.bus_num
= params
[BUS_PARAM_ID
];
280 slave_info
.chip_select
= i
;
281 slave_info
.mode
= mode
;
283 master
= spi_busnum_to_master(params
[BUS_PARAM_ID
]);
285 printk(KERN_ERR PFX
"unable to get master for bus %d\n",
286 params
[BUS_PARAM_ID
]);
290 slave
= spi_new_device(master
, &slave_info
);
291 spi_master_put(master
);
293 printk(KERN_ERR PFX
"unable to create slave %d for bus %d\n",
294 i
, params
[BUS_PARAM_ID
]);
295 /* Will most likely fail due to unsupported mode bits */
301 devices
[nr_devices
++] = pdev
;
306 platform_device_unregister(pdev
);
311 static int __init
spi_gpio_custom_probe(void)
315 printk(KERN_INFO DRV_DESC
" version " DRV_VERSION
"\n");
317 err
= spi_gpio_custom_add_one(0, bus0
);
321 err
= spi_gpio_custom_add_one(1, bus1
);
325 err
= spi_gpio_custom_add_one(2, bus2
);
329 err
= spi_gpio_custom_add_one(3, bus3
);
334 printk(KERN_ERR PFX
"no bus parameter(s) specified\n");
342 spi_gpio_custom_cleanup();
347 static int __init
spi_gpio_custom_init(void)
349 return spi_gpio_custom_probe();
351 module_init(spi_gpio_custom_init
);
353 static void __exit
spi_gpio_custom_exit(void)
355 spi_gpio_custom_cleanup();
357 module_exit(spi_gpio_custom_exit
);
359 subsys_initcall(spi_gpio_custom_probe
);
362 MODULE_LICENSE("GPL v2");
363 MODULE_AUTHOR("Marco Burato <zmaster.adsl@gmail.com>");
364 MODULE_DESCRIPTION(DRV_DESC
);
365 MODULE_VERSION(DRV_VERSION
);