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_warn("Simple test 1: FAILURE: spi_write_then_read failed with status %d\n",
84 			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_warn("Simple test 2: FAILURE: spi_write_then_read() failed with status %d\n",
93 			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_warn("Simple test 3: FAILURE: failed with status %d (probably FIFO overrun)\n",
102 			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_warn("Simple test 4 step 1: FAILURE: spi_write() failed with status %d\n",
111 			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_warn("Simple test 4 step 2: FAILURE: spi_read() failed with status %d\n",
117 			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_warn("Simple test 5 step 1: FAILURE: spi_write() failed with status %d (probably FIFO overrun)\n",
126 			status);
127 	else
128 		pr_info("Simple test 5 step 1: SUCCESS!\n");
129 	status = spi_read(spi, &rxbuf[0], 14);
130 	if (status < 0)
131 		pr_warn("Simple test 5 step 2: FAILURE: spi_read() failed with status %d (probably FIFO overrun)\n",
132 			status);
133 	else
134 		pr_info("Simple test 5: SUCCESS!\n");
135 
136 	pr_info("Simple test 6: write %d bytes with spi_write(), "
137 		"read %d bytes garbage with spi_read() in 8bit mode\n",
138 		DMA_TEST_SIZE, DMA_TEST_SIZE);
139 	status = spi_write(spi, &bigtxbuf_virtual[0], DMA_TEST_SIZE);
140 	if (status < 0)
141 		pr_warn("Simple test 6 step 1: FAILURE: spi_write() failed with status %d (probably FIFO overrun)\n",
142 			status);
143 	else
144 		pr_info("Simple test 6 step 1: SUCCESS!\n");
145 	status = spi_read(spi, &bigrxbuf_virtual[0], DMA_TEST_SIZE);
146 	if (status < 0)
147 		pr_warn("Simple test 6 step 2: FAILURE: spi_read() failed with status %d (probably FIFO overrun)\n",
148 			status);
149 	else
150 		pr_info("Simple test 6: SUCCESS!\n");
151 
152 
153 	/*
154 	 * Force chip to 16 bit mode
155 	 * WARNING: NEVER DO THIS IN REAL DRIVER CODE, THIS SHOULD BE STATIC!
156 	 */
157 	spi->bits_per_word = 16;
158 	/* You should NOT DO THIS EITHER */
159 	spi->master->setup(spi);
160 
161 	pr_info("Simple test 7: write 0xAA byte, read back garbage byte "
162 		"in 16bit bus mode\n");
163 	status = spi_w8r8(spi, 0xAA);
164 	if (status == -EIO)
165 		pr_info("Simple test 7: SUCCESS! (expected failure with "
166 			"status EIO)\n");
167 	else if (status < 0)
168 		pr_warn("Simple test 7: FAILURE: spi_write_then_read failed with status %d\n",
169 			status);
170 	else
171 		pr_warn("Simple test 7: FAILURE: spi_write_then_read succeeded but it was expected to fail!\n");
172 
173 	pr_info("Simple test 8: write 8 bytes, read back 8 bytes garbage "
174 		"in 16bit mode (full FIFO)\n");
175 	status = spi_write_then_read(spi, &txbuf[0], 8, &rxbuf[0], 8);
176 	if (status < 0)
177 		pr_warn("Simple test 8: FAILURE: spi_write_then_read() failed with status %d\n",
178 			status);
179 	else
180 		pr_info("Simple test 8: SUCCESS!\n");
181 
182 	pr_info("Simple test 9: write 14 bytes, read back 14 bytes garbage "
183 		"in 16bit mode (see if we overflow FIFO)\n");
184 	status = spi_write_then_read(spi, &txbuf[0], 14, &rxbuf[0], 14);
185 	if (status < 0)
186 		pr_warn("Simple test 9: FAILURE: failed with status %d (probably FIFO overrun)\n",
187 			status);
188 	else
189 		pr_info("Simple test 9: SUCCESS!\n");
190 
191 	pr_info("Simple test 10: write %d bytes with spi_write(), "
192 	       "read %d bytes garbage with spi_read() in 16bit mode\n",
193 	       DMA_TEST_SIZE, DMA_TEST_SIZE);
194 	status = spi_write(spi, &bigtxbuf_virtual[0], DMA_TEST_SIZE);
195 	if (status < 0)
196 		pr_warn("Simple test 10 step 1: FAILURE: spi_write() failed with status %d (probably FIFO overrun)\n",
197 			status);
198 	else
199 		pr_info("Simple test 10 step 1: SUCCESS!\n");
200 
201 	status = spi_read(spi, &bigrxbuf_virtual[0], DMA_TEST_SIZE);
202 	if (status < 0)
203 		pr_warn("Simple test 10 step 2: FAILURE: spi_read() failed with status %d (probably FIFO overrun)\n",
204 			status);
205 	else
206 		pr_info("Simple test 10: SUCCESS!\n");
207 
208 	status = sprintf(buf, "loop test complete\n");
209 	kfree(bigrxbuf_virtual);
210 	kfree(bigtxbuf_virtual);
211  out:
212 	mutex_unlock(&p_dummy->lock);
213 	return status;
214 }
215 
216 static DEVICE_ATTR(looptest, S_IRUGO, dummy_looptest, NULL);
217 
pl022_dummy_probe(struct spi_device * spi)218 static int pl022_dummy_probe(struct spi_device *spi)
219 {
220 	struct dummy *p_dummy;
221 	int status;
222 
223 	dev_info(&spi->dev, "probing dummy SPI device\n");
224 
225 	p_dummy = kzalloc(sizeof *p_dummy, GFP_KERNEL);
226 	if (!p_dummy)
227 		return -ENOMEM;
228 
229 	dev_set_drvdata(&spi->dev, p_dummy);
230 	mutex_init(&p_dummy->lock);
231 
232 	/* sysfs hook */
233 	status = device_create_file(&spi->dev, &dev_attr_looptest);
234 	if (status) {
235 		dev_dbg(&spi->dev, "device_create_file looptest failure.\n");
236 		goto out_dev_create_looptest_failed;
237 	}
238 
239 	return 0;
240 
241 out_dev_create_looptest_failed:
242 	dev_set_drvdata(&spi->dev, NULL);
243 	kfree(p_dummy);
244 	return status;
245 }
246 
pl022_dummy_remove(struct spi_device * spi)247 static int pl022_dummy_remove(struct spi_device *spi)
248 {
249 	struct dummy *p_dummy = dev_get_drvdata(&spi->dev);
250 
251 	dev_info(&spi->dev, "removing dummy SPI device\n");
252 	device_remove_file(&spi->dev, &dev_attr_looptest);
253 	dev_set_drvdata(&spi->dev, NULL);
254 	kfree(p_dummy);
255 
256 	return 0;
257 }
258 
259 static const struct of_device_id pl022_dummy_dt_match[] = {
260 	{ .compatible = "arm,pl022-dummy" },
261 	{},
262 };
263 
264 static struct spi_driver pl022_dummy_driver = {
265 	.driver = {
266 		.name	= "spi-dummy",
267 		.of_match_table = pl022_dummy_dt_match,
268 	},
269 	.probe	= pl022_dummy_probe,
270 	.remove	= pl022_dummy_remove,
271 };
272 
273 module_spi_driver(pl022_dummy_driver);
274 MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
275 MODULE_DESCRIPTION("PL022 SSP/SPI DUMMY Linux driver");
276 MODULE_LICENSE("GPL");
277