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dummyspichip.c
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1 /*
2  * arch/arm/mach-u300/dummyspichip.c
3  *
4  * Copyright (C) 2007-2009 ST-Ericsson AB
5  * License terms: GNU General Public License (GPL) version 2
6  * This is a dummy loopback SPI "chip" used for testing SPI.
7  * Author: Linus Walleij <[email protected]>
8  */
9 #include <linux/init.h>
10 #include <linux/module.h>
11 #include <linux/kernel.h>
12 #include <linux/device.h>
13 #include <linux/err.h>
14 #include <linux/sysfs.h>
15 #include <linux/mutex.h>
16 #include <linux/spi/spi.h>
17 #include <linux/dma-mapping.h>
18 #include <linux/slab.h>
19 /*
20  * WARNING! Do not include this pl022-specific controller header
21  * for any generic driver. It is only done in this dummy chip
22  * because we alter the chip configuration in order to test some
23  * different settings on the loopback device. Normal chip configs
24  * shall be STATIC and not altered by the driver!
25  */
26 #include <linux/amba/pl022.h>
27 
28 struct dummy {
29  struct device *dev;
30  struct mutex lock;
31 };
32 
33 #define DMA_TEST_SIZE 2048
34 
35 /* When we cat /sys/bus/spi/devices/spi0.0/looptest this will be triggered */
36 static ssize_t dummy_looptest(struct device *dev,
37  struct device_attribute *attr, char *buf)
38 {
39  struct spi_device *spi = to_spi_device(dev);
40  struct dummy *p_dummy = dev_get_drvdata(&spi->dev);
41 
42  /*
43  * WARNING! Do not dereference the chip-specific data in any normal
44  * driver for a chip. It is usually STATIC and shall not be read
45  * or written to. Your chip driver should NOT depend on fields in this
46  * struct, this is just used here to alter the behaviour of the chip
47  * in order to perform tests.
48  */
49  int status;
50  u8 txbuf[14] = {0xDE, 0xAD, 0xBE, 0xEF, 0x2B, 0xAD,
51  0xCA, 0xFE, 0xBA, 0xBE, 0xB1, 0x05,
52  0xF0, 0x0D};
53  u8 rxbuf[14];
54  u8 *bigtxbuf_virtual;
55  u8 *bigrxbuf_virtual;
56 
57  if (mutex_lock_interruptible(&p_dummy->lock))
58  return -ERESTARTSYS;
59 
60  bigtxbuf_virtual = kmalloc(DMA_TEST_SIZE, GFP_KERNEL);
61  if (bigtxbuf_virtual == NULL) {
62  status = -ENOMEM;
63  goto out;
64  }
65  bigrxbuf_virtual = kmalloc(DMA_TEST_SIZE, GFP_KERNEL);
66 
67  /* Fill TXBUF with some happy pattern */
68  memset(bigtxbuf_virtual, 0xAA, DMA_TEST_SIZE);
69 
70  /*
71  * Force chip to 8 bit mode
72  * WARNING: NEVER DO THIS IN REAL DRIVER CODE, THIS SHOULD BE STATIC!
73  */
74  spi->bits_per_word = 8;
75  /* You should NOT DO THIS EITHER */
76  spi->master->setup(spi);
77 
78  /* Now run the tests for 8bit mode */
79  pr_info("Simple test 1: write 0xAA byte, read back garbage byte "
80  "in 8bit mode\n");
81  status = spi_w8r8(spi, 0xAA);
82  if (status < 0)
83  pr_warning("Siple test 1: FAILURE: spi_write_then_read "
84  "failed with status %d\n", status);
85  else
86  pr_info("Simple test 1: SUCCESS!\n");
87 
88  pr_info("Simple test 2: write 8 bytes, read back 8 bytes garbage "
89  "in 8bit mode (full FIFO)\n");
90  status = spi_write_then_read(spi, &txbuf[0], 8, &rxbuf[0], 8);
91  if (status < 0)
92  pr_warning("Simple test 2: FAILURE: spi_write_then_read() "
93  "failed with status %d\n", status);
94  else
95  pr_info("Simple test 2: SUCCESS!\n");
96 
97  pr_info("Simple test 3: write 14 bytes, read back 14 bytes garbage "
98  "in 8bit mode (see if we overflow FIFO)\n");
99  status = spi_write_then_read(spi, &txbuf[0], 14, &rxbuf[0], 14);
100  if (status < 0)
101  pr_warning("Simple test 3: FAILURE: failed with status %d "
102  "(probably FIFO overrun)\n", status);
103  else
104  pr_info("Simple test 3: SUCCESS!\n");
105 
106  pr_info("Simple test 4: write 8 bytes with spi_write(), read 8 "
107  "bytes garbage with spi_read() in 8bit mode\n");
108  status = spi_write(spi, &txbuf[0], 8);
109  if (status < 0)
110  pr_warning("Simple test 4 step 1: FAILURE: spi_write() "
111  "failed with status %d\n", status);
112  else
113  pr_info("Simple test 4 step 1: SUCCESS!\n");
114  status = spi_read(spi, &rxbuf[0], 8);
115  if (status < 0)
116  pr_warning("Simple test 4 step 2: FAILURE: spi_read() "
117  "failed with status %d\n", status);
118  else
119  pr_info("Simple test 4 step 2: SUCCESS!\n");
120 
121  pr_info("Simple test 5: write 14 bytes with spi_write(), read "
122  "14 bytes garbage with spi_read() in 8bit mode\n");
123  status = spi_write(spi, &txbuf[0], 14);
124  if (status < 0)
125  pr_warning("Simple test 5 step 1: FAILURE: spi_write() "
126  "failed with status %d (probably FIFO overrun)\n",
127  status);
128  else
129  pr_info("Simple test 5 step 1: SUCCESS!\n");
130  status = spi_read(spi, &rxbuf[0], 14);
131  if (status < 0)
132  pr_warning("Simple test 5 step 2: FAILURE: spi_read() "
133  "failed with status %d (probably FIFO overrun)\n",
134  status);
135  else
136  pr_info("Simple test 5: SUCCESS!\n");
137 
138  pr_info("Simple test 6: write %d bytes with spi_write(), "
139  "read %d bytes garbage with spi_read() in 8bit mode\n",
140  DMA_TEST_SIZE, DMA_TEST_SIZE);
141  status = spi_write(spi, &bigtxbuf_virtual[0], DMA_TEST_SIZE);
142  if (status < 0)
143  pr_warning("Simple test 6 step 1: FAILURE: spi_write() "
144  "failed with status %d (probably FIFO overrun)\n",
145  status);
146  else
147  pr_info("Simple test 6 step 1: SUCCESS!\n");
148  status = spi_read(spi, &bigrxbuf_virtual[0], DMA_TEST_SIZE);
149  if (status < 0)
150  pr_warning("Simple test 6 step 2: FAILURE: spi_read() "
151  "failed with status %d (probably FIFO overrun)\n",
152  status);
153  else
154  pr_info("Simple test 6: SUCCESS!\n");
155 
156 
157  /*
158  * Force chip to 16 bit mode
159  * WARNING: NEVER DO THIS IN REAL DRIVER CODE, THIS SHOULD BE STATIC!
160  */
161  spi->bits_per_word = 16;
162  /* You should NOT DO THIS EITHER */
163  spi->master->setup(spi);
164 
165  pr_info("Simple test 7: write 0xAA byte, read back garbage byte "
166  "in 16bit bus mode\n");
167  status = spi_w8r8(spi, 0xAA);
168  if (status == -EIO)
169  pr_info("Simple test 7: SUCCESS! (expected failure with "
170  "status EIO)\n");
171  else if (status < 0)
172  pr_warning("Siple test 7: FAILURE: spi_write_then_read "
173  "failed with status %d\n", status);
174  else
175  pr_warning("Siple test 7: FAILURE: spi_write_then_read "
176  "succeeded but it was expected to fail!\n");
177 
178  pr_info("Simple test 8: write 8 bytes, read back 8 bytes garbage "
179  "in 16bit mode (full FIFO)\n");
180  status = spi_write_then_read(spi, &txbuf[0], 8, &rxbuf[0], 8);
181  if (status < 0)
182  pr_warning("Simple test 8: FAILURE: spi_write_then_read() "
183  "failed with status %d\n", status);
184  else
185  pr_info("Simple test 8: SUCCESS!\n");
186 
187  pr_info("Simple test 9: write 14 bytes, read back 14 bytes garbage "
188  "in 16bit mode (see if we overflow FIFO)\n");
189  status = spi_write_then_read(spi, &txbuf[0], 14, &rxbuf[0], 14);
190  if (status < 0)
191  pr_warning("Simple test 9: FAILURE: failed with status %d "
192  "(probably FIFO overrun)\n", status);
193  else
194  pr_info("Simple test 9: SUCCESS!\n");
195 
196  pr_info("Simple test 10: write %d bytes with spi_write(), "
197  "read %d bytes garbage with spi_read() in 16bit mode\n",
198  DMA_TEST_SIZE, DMA_TEST_SIZE);
199  status = spi_write(spi, &bigtxbuf_virtual[0], DMA_TEST_SIZE);
200  if (status < 0)
201  pr_warning("Simple test 10 step 1: FAILURE: spi_write() "
202  "failed with status %d (probably FIFO overrun)\n",
203  status);
204  else
205  pr_info("Simple test 10 step 1: SUCCESS!\n");
206 
207  status = spi_read(spi, &bigrxbuf_virtual[0], DMA_TEST_SIZE);
208  if (status < 0)
209  pr_warning("Simple test 10 step 2: FAILURE: spi_read() "
210  "failed with status %d (probably FIFO overrun)\n",
211  status);
212  else
213  pr_info("Simple test 10: SUCCESS!\n");
214 
215  status = sprintf(buf, "loop test complete\n");
216  kfree(bigrxbuf_virtual);
217  kfree(bigtxbuf_virtual);
218  out:
219  mutex_unlock(&p_dummy->lock);
220  return status;
221 }
222 
223 static DEVICE_ATTR(looptest, S_IRUGO, dummy_looptest, NULL);
224 
225 static int __devinit pl022_dummy_probe(struct spi_device *spi)
226 {
227  struct dummy *p_dummy;
228  int status;
229 
230  dev_info(&spi->dev, "probing dummy SPI device\n");
231 
232  p_dummy = kzalloc(sizeof *p_dummy, GFP_KERNEL);
233  if (!p_dummy)
234  return -ENOMEM;
235 
236  dev_set_drvdata(&spi->dev, p_dummy);
237  mutex_init(&p_dummy->lock);
238 
239  /* sysfs hook */
240  status = device_create_file(&spi->dev, &dev_attr_looptest);
241  if (status) {
242  dev_dbg(&spi->dev, "device_create_file looptest failure.\n");
243  goto out_dev_create_looptest_failed;
244  }
245 
246  return 0;
247 
248 out_dev_create_looptest_failed:
249  dev_set_drvdata(&spi->dev, NULL);
250  kfree(p_dummy);
251  return status;
252 }
253 
254 static int __devexit pl022_dummy_remove(struct spi_device *spi)
255 {
256  struct dummy *p_dummy = dev_get_drvdata(&spi->dev);
257 
258  dev_info(&spi->dev, "removing dummy SPI device\n");
259  device_remove_file(&spi->dev, &dev_attr_looptest);
260  dev_set_drvdata(&spi->dev, NULL);
261  kfree(p_dummy);
262 
263  return 0;
264 }
265 
266 static struct spi_driver pl022_dummy_driver = {
267  .driver = {
268  .name = "spi-dummy",
269  .owner = THIS_MODULE,
270  },
271  .probe = pl022_dummy_probe,
272  .remove = __devexit_p(pl022_dummy_remove),
273 };
274 
275 static int __init pl022_init_dummy(void)
276 {
277  return spi_register_driver(&pl022_dummy_driver);
278 }
279 
280 static void __exit pl022_exit_dummy(void)
281 {
282  spi_unregister_driver(&pl022_dummy_driver);
283 }
284 
285 module_init(pl022_init_dummy);
286 module_exit(pl022_exit_dummy);
287 
288 MODULE_AUTHOR("Linus Walleij <[email protected]>");
289 MODULE_DESCRIPTION("PL022 SSP/SPI DUMMY Linux driver");
290 MODULE_LICENSE("GPL");
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