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 <linus.walleij@stericsson.com>
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 */
dummy_looptest(struct device * dev,struct device_attribute * attr,char * buf)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 
pl022_dummy_probe(struct spi_device * spi)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 
pl022_dummy_remove(struct spi_device * spi)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 
pl022_init_dummy(void)275 static int __init pl022_init_dummy(void)
276 {
277 	return spi_register_driver(&pl022_dummy_driver);
278 }
279 
pl022_exit_dummy(void)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 <linus.walleij@stericsson.com>");
289 MODULE_DESCRIPTION("PL022 SSP/SPI DUMMY Linux driver");
290 MODULE_LICENSE("GPL");
291