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4 office 1 /*
2 * Custom GPIO-based SPI driver
3 *
4 * Copyright (C) 2013 Marco Burato <zmaster.adsl@gmail.com>
5 *
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.
9 *
10 * Based on i2c-gpio-custom by:
11 * Copyright (C) 2007-2008 Gabor Juhos <juhosg@openwrt.org>
12 * ---------------------------------------------------------------------------
13 *
14 * The behaviour of this driver can be altered by setting some parameters
15 * from the insmod command line.
16 *
17 * The following parameters are adjustable:
18 *
19 * bus0 These four arguments can be arrays of
20 * bus1 1-8 unsigned integers as follows:
21 * bus2
22 * bus3 <id>,<sck>,<mosi>,<miso>,<mode1>,<maxfreq1>,<cs1>,...
23 *
24 * where:
25 *
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**)
34 *
35 * Notes:
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.
41 *
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:
45 *
46 * spi-gpio-custom.bus0
47 * spi-gpio-custom.bus1
48 * spi-gpio-custom.bus2
49 * spi-gpio-custom.bus3
50 */
51  
52 #include <linux/kernel.h>
53 #include <linux/module.h>
54 #include <linux/init.h>
55 #include <linux/platform_device.h>
56  
57 #include <linux/gpio.h>
58 #include <linux/spi/spi.h>
59 #include <linux/spi/spi_gpio.h>
60  
61 #define DRV_NAME "spi-gpio-custom"
62 #define DRV_DESC "Custom GPIO-based SPI driver"
63 #define DRV_VERSION "0.1"
64  
65 #define PFX DRV_NAME ": "
66  
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
74  
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
80  
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;
85  
86 static unsigned int bus_nump[BUS_COUNT_MAX] __initdata;
87  
88 #define BUS_PARM_DESC \
89 " config -> id,sck,mosi,miso,mode1,maxfreq1[,cs1,mode2,maxfreq2,cs2,...]"
90  
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);
99  
100 static struct platform_device *devices[BUS_COUNT_MAX];
101 static unsigned int nr_devices;
102  
103 static void spi_gpio_custom_cleanup(void)
104 {
105 int i;
106  
107 for (i = 0; i < nr_devices; i++)
108 if (devices[i])
109 platform_device_unregister(devices[i]);
110 }
111  
112 static int __init spi_gpio_custom_get_slave_mode(unsigned int id,
113 unsigned int *params,
114 int slave_index)
115 {
116 int param_index;
117  
118 param_index = BUS_PARAM_MODE1+slave_index*BUS_PARAM_PER_SLAVE;
119 if (param_index >= bus_nump[id])
120 return -1;
121  
122 return params[param_index];
123 }
124 static int __init spi_gpio_custom_get_slave_maxfreq(unsigned int id,
125 unsigned int *params,
126 int slave_index)
127 {
128 int param_index;
129  
130 param_index = BUS_PARAM_MAXFREQ1+slave_index*BUS_PARAM_PER_SLAVE;
131 if (param_index >= bus_nump[id])
132 return -1;
133  
134 return params[param_index];
135 }
136 static int __init spi_gpio_custom_get_slave_cs(unsigned int id,
137 unsigned int *params,
138 int slave_index)
139 {
140 int param_index;
141  
142 param_index = BUS_PARAM_CS1+slave_index*BUS_PARAM_PER_SLAVE;
143 if (param_index >= bus_nump[id])
144 return -1;
145 if (!gpio_is_valid(params[param_index]))
146 return -1;
147  
148 return params[param_index];
149 }
150  
151 static int __init spi_gpio_custom_check_params(unsigned int id, unsigned int *params)
152 {
153 int i;
154 struct spi_master *master;
155  
156 if (bus_nump[id] < BUS_PARAM_REQUIRED) {
157 printk(KERN_ERR PFX "not enough values for parameter bus%d\n",
158 id);
159 return -EINVAL;
160 }
161  
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)
167 break;
168  
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]);
172 return -EINVAL;
173 }
174 }
175 }
176  
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]);
180 return -EINVAL;
181 }
182  
183 master = spi_busnum_to_master(params[BUS_PARAM_ID]);
184 if (master) {
185 spi_master_put(master);
186 printk(KERN_ERR PFX "bus %d already exists\n",
187 params[BUS_PARAM_ID]);
188 return -EEXIST;
189 }
190  
191 return 0;
192 }
193  
194 static int __init spi_gpio_custom_add_one(unsigned int id, unsigned int *params)
195 {
196 struct platform_device *pdev;
197 struct spi_gpio_platform_data pdata;
198 int i;
199 int num_cs;
200 int err;
201 struct spi_master *master;
202 struct spi_device *slave;
203 struct spi_board_info slave_info;
204 int mode, maxfreq, cs;
205  
206  
207 if (!bus_nump[id])
208 return 0;
209  
210 err = spi_gpio_custom_check_params(id, params);
211 if (err)
212 goto err;
213  
214 /* Create BUS device node */
215  
216 pdev = platform_device_alloc("spi_gpio", params[BUS_PARAM_ID]);
217 if (!pdev) {
218 err = -ENOMEM;
219 goto err;
220 }
221  
222 num_cs = 0;
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)
226 break;
227  
228 if (spi_gpio_custom_get_slave_cs(id, params, i) >= 0)
229 num_cs++;
230 }
231 if (num_cs == 0) {
232 /*
233 * Even if no CS is used, spi modules expect
234 * at least 1 (unused)
235 */
236 num_cs = 1;
237 }
238  
239 pdata.sck = params[BUS_PARAM_SCK];
240 pdata.mosi = gpio_is_valid(params[BUS_PARAM_MOSI])
241 ? params[BUS_PARAM_MOSI]
242 : SPI_GPIO_NO_MOSI;
243 pdata.miso = gpio_is_valid(params[BUS_PARAM_MISO])
244 ? params[BUS_PARAM_MISO]
245 : SPI_GPIO_NO_MISO;
246 pdata.num_chipselect = num_cs;
247  
248 err = platform_device_add_data(pdev, &pdata, sizeof(pdata));
249 if (err) {
250 platform_device_put(pdev);
251 goto err;
252 }
253  
254 err = platform_device_add(pdev);
255 if (err) {
256 printk(KERN_ERR PFX "platform_device_add failed with return code %d\n",
257 err);
258 platform_device_put(pdev);
259 goto err;
260 }
261  
262 /* Register SLAVE devices */
263  
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);
268  
269 /* no more slaves? */
270 if (mode < 0)
271 break;
272  
273 memset(&slave_info, 0, sizeof(slave_info));
274 strcpy(slave_info.modalias, "spidev");
275 slave_info.controller_data = (void *)((cs >= 0)
276 ? cs
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;
282  
283 master = spi_busnum_to_master(params[BUS_PARAM_ID]);
284 if (!master) {
285 printk(KERN_ERR PFX "unable to get master for bus %d\n",
286 params[BUS_PARAM_ID]);
287 err = -EINVAL;
288 goto err_unregister;
289 }
290 slave = spi_new_device(master, &slave_info);
291 spi_master_put(master);
292 if (!slave) {
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 */
296 err = -EINVAL;
297 goto err_unregister;
298 }
299 }
300  
301 devices[nr_devices++] = pdev;
302  
303 return 0;
304  
305 err_unregister:
306 platform_device_unregister(pdev);
307 err:
308 return err;
309 }
310  
311 static int __init spi_gpio_custom_probe(void)
312 {
313 int err;
314  
315 printk(KERN_INFO DRV_DESC " version " DRV_VERSION "\n");
316  
317 err = spi_gpio_custom_add_one(0, bus0);
318 if (err)
319 goto err;
320  
321 err = spi_gpio_custom_add_one(1, bus1);
322 if (err)
323 goto err;
324  
325 err = spi_gpio_custom_add_one(2, bus2);
326 if (err)
327 goto err;
328  
329 err = spi_gpio_custom_add_one(3, bus3);
330 if (err)
331 goto err;
332  
333 if (!nr_devices) {
334 printk(KERN_ERR PFX "no bus parameter(s) specified\n");
335 err = -ENODEV;
336 goto err;
337 }
338  
339 return 0;
340  
341 err:
342 spi_gpio_custom_cleanup();
343 return err;
344 }
345  
346 #ifdef MODULE
347 static int __init spi_gpio_custom_init(void)
348 {
349 return spi_gpio_custom_probe();
350 }
351 module_init(spi_gpio_custom_init);
352  
353 static void __exit spi_gpio_custom_exit(void)
354 {
355 spi_gpio_custom_cleanup();
356 }
357 module_exit(spi_gpio_custom_exit);
358 #else
359 subsys_initcall(spi_gpio_custom_probe);
360 #endif /* MODULE*/
361  
362 MODULE_LICENSE("GPL v2");
363 MODULE_AUTHOR("Marco Burato <zmaster.adsl@gmail.com>");
364 MODULE_DESCRIPTION(DRV_DESC);
365 MODULE_VERSION(DRV_VERSION);