summaryrefslogtreecommitdiff
path: root/package/kernel/spi-gpio-custom/src/spi-gpio-custom.c
blob: 4c13b56d7930e3481d064814d230df9a14912f84 (plain)
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
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
/*
 *  Custom GPIO-based SPI driver
 *
 *  Copyright (C) 2013 Marco Burato <zmaster.adsl@gmail.com>
 *
 *  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.
 *
 *  Based on i2c-gpio-custom by:
 *  Copyright (C) 2007-2008 Gabor Juhos <juhosg@openwrt.org>
 * ---------------------------------------------------------------------------
 *
 *  The behaviour of this driver can be altered by setting some parameters
 *  from the insmod command line.
 *
 *  The following parameters are adjustable:
 *
 *	bus0	These four arguments can be arrays of
 *	bus1	1-8 unsigned integers as follows:
 *	bus2
 *	bus3	<id>,<sck>,<mosi>,<miso>,<mode1>,<maxfreq1>,<cs1>,...
 *
 *  where:
 *
 *  <id>	ID to used as device_id for the corresponding bus (required)
 *  <sck>	GPIO pin ID to be used for bus SCK (required)
 *  <mosi>	GPIO pin ID to be used for bus MOSI (required*)
 *  <miso>	GPIO pin ID to be used for bus MISO (required*)
 *  <modeX>	Mode configuration for slave X in the bus (required)
 *		(see /include/linux/spi/spi.h)
 *  <maxfreqX>	Maximum clock frequency in Hz for slave X in the bus (required)
 *  <csX>	GPIO pin ID to be used for slave X CS (required**)
 *
 *	Notes:
 *	*	If a signal is not used (for example there is no MISO) you need
 *		to set the GPIO pin ID for that signal to an invalid value.
 *	**	If you only have 1 slave in the bus with no CS, you can omit the
 *		<cs1> param or set it to an invalid GPIO id to disable it. When
 *		you have 2 or more slaves, they must all have a valid CS.
 *
 *  If this driver is built into the kernel, you can use the following kernel
 *  command line parameters, with the same values as the corresponding module
 *  parameters listed above:
 *
 *	spi-gpio-custom.bus0
 *	spi-gpio-custom.bus1
 *	spi-gpio-custom.bus2
 *	spi-gpio-custom.bus3
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/platform_device.h>

#include <linux/gpio.h>
#include <linux/spi/spi.h>
#include <linux/spi/spi_gpio.h>

#define DRV_NAME	"spi-gpio-custom"
#define DRV_DESC	"Custom GPIO-based SPI driver"
#define DRV_VERSION	"0.1"

#define PFX		DRV_NAME ": "

#define BUS_PARAM_ID		0
#define BUS_PARAM_SCK		1
#define BUS_PARAM_MOSI		2
#define BUS_PARAM_MISO		3
#define BUS_PARAM_MODE1		4
#define BUS_PARAM_MAXFREQ1	5
#define BUS_PARAM_CS1		6

#define BUS_SLAVE_COUNT_MAX	8
#define BUS_PARAM_REQUIRED	6
#define BUS_PARAM_PER_SLAVE	3
#define BUS_PARAM_COUNT		(4+BUS_PARAM_PER_SLAVE*BUS_SLAVE_COUNT_MAX)
#define BUS_COUNT_MAX		4

static unsigned int bus0[BUS_PARAM_COUNT] __initdata;
static unsigned int bus1[BUS_PARAM_COUNT] __initdata;
static unsigned int bus2[BUS_PARAM_COUNT] __initdata;
static unsigned int bus3[BUS_PARAM_COUNT] __initdata;

static unsigned int bus_nump[BUS_COUNT_MAX] __initdata;

#define BUS_PARM_DESC \
	" config -> id,sck,mosi,miso,mode1,maxfreq1[,cs1,mode2,maxfreq2,cs2,...]"

module_param_array(bus0, uint, &bus_nump[0], 0);
MODULE_PARM_DESC(bus0, "bus0" BUS_PARM_DESC);
module_param_array(bus1, uint, &bus_nump[1], 0);
MODULE_PARM_DESC(bus1, "bus1" BUS_PARM_DESC);
module_param_array(bus2, uint, &bus_nump[2], 0);
MODULE_PARM_DESC(bus2, "bus2" BUS_PARM_DESC);
module_param_array(bus3, uint, &bus_nump[3], 0);
MODULE_PARM_DESC(bus3, "bus3" BUS_PARM_DESC);

static struct platform_device *devices[BUS_COUNT_MAX];
static unsigned int nr_devices;

static void spi_gpio_custom_cleanup(void)
{
	int i;

	for (i = 0; i < nr_devices; i++)
		if (devices[i])
			platform_device_unregister(devices[i]);
}

static int __init spi_gpio_custom_get_slave_mode(unsigned int id,
					  unsigned int *params,
					  int slave_index)
{
	int param_index;

	param_index = BUS_PARAM_MODE1+slave_index*BUS_PARAM_PER_SLAVE;
	if (param_index >= bus_nump[id])
		return -1;

	return params[param_index];
}
static int __init spi_gpio_custom_get_slave_maxfreq(unsigned int id,
					     unsigned int *params,
					     int slave_index)
{
	int param_index;

	param_index = BUS_PARAM_MAXFREQ1+slave_index*BUS_PARAM_PER_SLAVE;
	if (param_index >= bus_nump[id])
		return -1;

	return params[param_index];
}
static int __init spi_gpio_custom_get_slave_cs(unsigned int id,
					unsigned int *params,
					int slave_index)
{
	int param_index;

	param_index = BUS_PARAM_CS1+slave_index*BUS_PARAM_PER_SLAVE;
	if (param_index >= bus_nump[id])
		return -1;
	if (!gpio_is_valid(params[param_index]))
		return -1;

	return params[param_index];
}

static int __init spi_gpio_custom_check_params(unsigned int id, unsigned int *params)
{
	int i;
	struct spi_master *master;

	if (bus_nump[id] < BUS_PARAM_REQUIRED) {
		printk(KERN_ERR PFX "not enough values for parameter bus%d\n",
		       id);
		return -EINVAL;
	}

	if (bus_nump[id] > (1+BUS_PARAM_CS1)) {
		/* more than 1 device: check CS GPIOs */
		for (i = 0; i < BUS_SLAVE_COUNT_MAX; i++) {
			/* no more slaves? */
			if (spi_gpio_custom_get_slave_mode(id, params, i) < 0)
				break;

			if (spi_gpio_custom_get_slave_cs(id, params, i) < 0) {
				printk(KERN_ERR PFX "invalid/missing CS gpio for slave %d on bus %d\n",
				       i, params[BUS_PARAM_ID]);
				return -EINVAL;
			}
		}
	}

	if (!gpio_is_valid(params[BUS_PARAM_SCK])) {
		printk(KERN_ERR PFX "invalid SCK gpio for bus %d\n",
		       params[BUS_PARAM_ID]);
		return -EINVAL;
	}

	master = spi_busnum_to_master(params[BUS_PARAM_ID]);
	if (master) {
		spi_master_put(master);
		printk(KERN_ERR PFX "bus %d already exists\n",
		       params[BUS_PARAM_ID]);
		return -EEXIST;
	}

	return 0;
}

static int __init spi_gpio_custom_add_one(unsigned int id, unsigned int *params)
{
	struct platform_device *pdev;
	struct spi_gpio_platform_data pdata;
	int i;
	int num_cs;
	int err;
	struct spi_master *master;
	struct spi_device *slave;
	struct spi_board_info slave_info;
	int mode, maxfreq, cs;


	if (!bus_nump[id])
		return 0;

	err = spi_gpio_custom_check_params(id, params);
	if (err)
		goto err;

	/* Create BUS device node */

	pdev = platform_device_alloc("spi_gpio", params[BUS_PARAM_ID]);
	if (!pdev) {
		err = -ENOMEM;
		goto err;
	}

	num_cs = 0;
	for (i = 0; i < BUS_SLAVE_COUNT_MAX; i++) {
		/* no more slaves? */
		if (spi_gpio_custom_get_slave_mode(id, params, i) < 0)
			break;

		if (spi_gpio_custom_get_slave_cs(id, params, i) >= 0)
			num_cs++;
	}
	if (num_cs == 0) {
		/*
		 * Even if no CS is used, spi modules expect
		 * at least 1 (unused)
		 */
		num_cs = 1;
	}

	pdata.sck = params[BUS_PARAM_SCK];
	pdata.mosi = gpio_is_valid(params[BUS_PARAM_MOSI])
		? params[BUS_PARAM_MOSI]
		: SPI_GPIO_NO_MOSI;
	pdata.miso = gpio_is_valid(params[BUS_PARAM_MISO])
		? params[BUS_PARAM_MISO]
		: SPI_GPIO_NO_MISO;
	pdata.num_chipselect = num_cs;

	err = platform_device_add_data(pdev, &pdata, sizeof(pdata));
	if (err) {
		platform_device_put(pdev);
		goto err;
	}

	err = platform_device_add(pdev);
	if (err) {
		printk(KERN_ERR PFX "platform_device_add failed with return code %d\n",
		       err);
		platform_device_put(pdev);
		goto err;
	}

	/* Register SLAVE devices */

	for (i = 0; i < BUS_SLAVE_COUNT_MAX; i++) {
		mode = spi_gpio_custom_get_slave_mode(id, params, i);
		maxfreq = spi_gpio_custom_get_slave_maxfreq(id, params, i);
		cs = spi_gpio_custom_get_slave_cs(id, params, i);

		/* no more slaves? */
		if (mode < 0)
			break;

		memset(&slave_info, 0, sizeof(slave_info));
		strcpy(slave_info.modalias, "spidev");
		slave_info.controller_data = (void *)((cs >= 0)
			? cs
			: SPI_GPIO_NO_CHIPSELECT);
		slave_info.max_speed_hz = maxfreq;
		slave_info.bus_num = params[BUS_PARAM_ID];
		slave_info.chip_select = i;
		slave_info.mode = mode;

		master = spi_busnum_to_master(params[BUS_PARAM_ID]);
		if (!master) {
			printk(KERN_ERR PFX "unable to get master for bus %d\n",
			       params[BUS_PARAM_ID]);
			err = -EINVAL;
			goto err_unregister;
		}
		slave = spi_new_device(master, &slave_info);
		spi_master_put(master);
		if (!slave) {
			printk(KERN_ERR PFX "unable to create slave %d for bus %d\n",
			       i, params[BUS_PARAM_ID]);
			/* Will most likely fail due to unsupported mode bits */
			err = -EINVAL;
			goto err_unregister;
		}
	}

	devices[nr_devices++] = pdev;

	return 0;

err_unregister:
	platform_device_unregister(pdev);
err:
	return err;
}

static int __init spi_gpio_custom_probe(void)
{
	int err;

	printk(KERN_INFO DRV_DESC " version " DRV_VERSION "\n");

	err = spi_gpio_custom_add_one(0, bus0);
	if (err)
		goto err;

	err = spi_gpio_custom_add_one(1, bus1);
	if (err)
		goto err;

	err = spi_gpio_custom_add_one(2, bus2);
	if (err)
		goto err;

	err = spi_gpio_custom_add_one(3, bus3);
	if (err)
		goto err;

	if (!nr_devices) {
		printk(KERN_ERR PFX "no bus parameter(s) specified\n");
		err = -ENODEV;
		goto err;
	}

	return 0;

err:
	spi_gpio_custom_cleanup();
	return err;
}

#ifdef MODULE
static int __init spi_gpio_custom_init(void)
{
	return spi_gpio_custom_probe();
}
module_init(spi_gpio_custom_init);

static void __exit spi_gpio_custom_exit(void)
{
	spi_gpio_custom_cleanup();
}
module_exit(spi_gpio_custom_exit);
#else
subsys_initcall(spi_gpio_custom_probe);
#endif /* MODULE*/

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Marco Burato <zmaster.adsl@gmail.com>");
MODULE_DESCRIPTION(DRV_DESC);
MODULE_VERSION(DRV_VERSION);