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* arch/arm/mach-u300/dummyspichip.c
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* Copyright (C) 2007-2009 ST-Ericsson AB
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* License terms: GNU General Public License (GPL) version 2
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* This is a dummy loopback SPI "chip" used for testing SPI.
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* Author: Linus Walleij <linus.walleij@stericsson.com>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/sysfs.h>
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#include <linux/mutex.h>
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#include <linux/spi/spi.h>
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#include <linux/dma-mapping.h>
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#include <linux/slab.h>
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* WARNING! Do not include this pl022-specific controller header
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* for any generic driver. It is only done in this dummy chip
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* because we alter the chip configuration in order to test some
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* different settings on the loopback device. Normal chip configs
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* shall be STATIC and not altered by the driver!
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#include <linux/amba/pl022.h>
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#define DMA_TEST_SIZE 2048
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/* When we cat /sys/bus/spi/devices/spi0.0/looptest this will be triggered */
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static ssize_t dummy_looptest(struct device *dev,
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struct device_attribute *attr, char *buf)
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struct spi_device *spi = to_spi_device(dev);
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struct dummy *p_dummy = dev_get_drvdata(&spi->dev);
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* WARNING! Do not dereference the chip-specific data in any normal
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* driver for a chip. It is usually STATIC and shall not be read
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* or written to. Your chip driver should NOT depend on fields in this
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* struct, this is just used here to alter the behaviour of the chip
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* in order to perform tests.
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u8 txbuf[14] = {0xDE, 0xAD, 0xBE, 0xEF, 0x2B, 0xAD,
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0xCA, 0xFE, 0xBA, 0xBE, 0xB1, 0x05,
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if (mutex_lock_interruptible(&p_dummy->lock))
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bigtxbuf_virtual = kmalloc(DMA_TEST_SIZE, GFP_KERNEL);
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if (bigtxbuf_virtual == NULL) {
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bigrxbuf_virtual = kmalloc(DMA_TEST_SIZE, GFP_KERNEL);
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/* Fill TXBUF with some happy pattern */
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memset(bigtxbuf_virtual, 0xAA, DMA_TEST_SIZE);
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* Force chip to 8 bit mode
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* WARNING: NEVER DO THIS IN REAL DRIVER CODE, THIS SHOULD BE STATIC!
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spi->bits_per_word = 8;
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/* You should NOT DO THIS EITHER */
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spi->master->setup(spi);
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/* Now run the tests for 8bit mode */
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pr_info("Simple test 1: write 0xAA byte, read back garbage byte "
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status = spi_w8r8(spi, 0xAA);
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pr_warning("Siple test 1: FAILURE: spi_write_then_read "
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"failed with status %d\n", status);
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pr_info("Simple test 1: SUCCESS!\n");
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pr_info("Simple test 2: write 8 bytes, read back 8 bytes garbage "
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"in 8bit mode (full FIFO)\n");
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status = spi_write_then_read(spi, &txbuf[0], 8, &rxbuf[0], 8);
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pr_warning("Simple test 2: FAILURE: spi_write_then_read() "
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"failed with status %d\n", status);
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pr_info("Simple test 2: SUCCESS!\n");
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pr_info("Simple test 3: write 14 bytes, read back 14 bytes garbage "
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"in 8bit mode (see if we overflow FIFO)\n");
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status = spi_write_then_read(spi, &txbuf[0], 14, &rxbuf[0], 14);
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pr_warning("Simple test 3: FAILURE: failed with status %d "
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"(probably FIFO overrun)\n", status);
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pr_info("Simple test 3: SUCCESS!\n");
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pr_info("Simple test 4: write 8 bytes with spi_write(), read 8 "
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"bytes garbage with spi_read() in 8bit mode\n");
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status = spi_write(spi, &txbuf[0], 8);
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pr_warning("Simple test 4 step 1: FAILURE: spi_write() "
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"failed with status %d\n", status);
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pr_info("Simple test 4 step 1: SUCCESS!\n");
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status = spi_read(spi, &rxbuf[0], 8);
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pr_warning("Simple test 4 step 2: FAILURE: spi_read() "
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"failed with status %d\n", status);
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pr_info("Simple test 4 step 2: SUCCESS!\n");
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pr_info("Simple test 5: write 14 bytes with spi_write(), read "
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"14 bytes garbage with spi_read() in 8bit mode\n");
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status = spi_write(spi, &txbuf[0], 14);
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pr_warning("Simple test 5 step 1: FAILURE: spi_write() "
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"failed with status %d (probably FIFO overrun)\n",
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pr_info("Simple test 5 step 1: SUCCESS!\n");
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status = spi_read(spi, &rxbuf[0], 14);
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pr_warning("Simple test 5 step 2: FAILURE: spi_read() "
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"failed with status %d (probably FIFO overrun)\n",
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pr_info("Simple test 5: SUCCESS!\n");
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pr_info("Simple test 6: write %d bytes with spi_write(), "
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"read %d bytes garbage with spi_read() in 8bit mode\n",
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DMA_TEST_SIZE, DMA_TEST_SIZE);
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status = spi_write(spi, &bigtxbuf_virtual[0], DMA_TEST_SIZE);
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pr_warning("Simple test 6 step 1: FAILURE: spi_write() "
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"failed with status %d (probably FIFO overrun)\n",
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pr_info("Simple test 6 step 1: SUCCESS!\n");
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status = spi_read(spi, &bigrxbuf_virtual[0], DMA_TEST_SIZE);
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pr_warning("Simple test 6 step 2: FAILURE: spi_read() "
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"failed with status %d (probably FIFO overrun)\n",
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pr_info("Simple test 6: SUCCESS!\n");
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* Force chip to 16 bit mode
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* WARNING: NEVER DO THIS IN REAL DRIVER CODE, THIS SHOULD BE STATIC!
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spi->bits_per_word = 16;
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/* You should NOT DO THIS EITHER */
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spi->master->setup(spi);
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pr_info("Simple test 7: write 0xAA byte, read back garbage byte "
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"in 16bit bus mode\n");
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status = spi_w8r8(spi, 0xAA);
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pr_info("Simple test 7: SUCCESS! (expected failure with "
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pr_warning("Siple test 7: FAILURE: spi_write_then_read "
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"failed with status %d\n", status);
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pr_warning("Siple test 7: FAILURE: spi_write_then_read "
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"succeeded but it was expected to fail!\n");
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pr_info("Simple test 8: write 8 bytes, read back 8 bytes garbage "
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"in 16bit mode (full FIFO)\n");
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status = spi_write_then_read(spi, &txbuf[0], 8, &rxbuf[0], 8);
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pr_warning("Simple test 8: FAILURE: spi_write_then_read() "
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"failed with status %d\n", status);
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pr_info("Simple test 8: SUCCESS!\n");
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pr_info("Simple test 9: write 14 bytes, read back 14 bytes garbage "
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"in 16bit mode (see if we overflow FIFO)\n");
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status = spi_write_then_read(spi, &txbuf[0], 14, &rxbuf[0], 14);
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pr_warning("Simple test 9: FAILURE: failed with status %d "
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"(probably FIFO overrun)\n", status);
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pr_info("Simple test 9: SUCCESS!\n");
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pr_info("Simple test 10: write %d bytes with spi_write(), "
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"read %d bytes garbage with spi_read() in 16bit mode\n",
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DMA_TEST_SIZE, DMA_TEST_SIZE);
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status = spi_write(spi, &bigtxbuf_virtual[0], DMA_TEST_SIZE);
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pr_warning("Simple test 10 step 1: FAILURE: spi_write() "
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"failed with status %d (probably FIFO overrun)\n",
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pr_info("Simple test 10 step 1: SUCCESS!\n");
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status = spi_read(spi, &bigrxbuf_virtual[0], DMA_TEST_SIZE);
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pr_warning("Simple test 10 step 2: FAILURE: spi_read() "
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"failed with status %d (probably FIFO overrun)\n",
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pr_info("Simple test 10: SUCCESS!\n");
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status = sprintf(buf, "loop test complete\n");
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kfree(bigrxbuf_virtual);
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kfree(bigtxbuf_virtual);
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mutex_unlock(&p_dummy->lock);
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static DEVICE_ATTR(looptest, S_IRUGO, dummy_looptest, NULL);
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static int __devinit pl022_dummy_probe(struct spi_device *spi)
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struct dummy *p_dummy;
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dev_info(&spi->dev, "probing dummy SPI device\n");
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p_dummy = kzalloc(sizeof *p_dummy, GFP_KERNEL);
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dev_set_drvdata(&spi->dev, p_dummy);
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mutex_init(&p_dummy->lock);
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status = device_create_file(&spi->dev, &dev_attr_looptest);
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dev_dbg(&spi->dev, "device_create_file looptest failure.\n");
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goto out_dev_create_looptest_failed;
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out_dev_create_looptest_failed:
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dev_set_drvdata(&spi->dev, NULL);
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static int __devexit pl022_dummy_remove(struct spi_device *spi)
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struct dummy *p_dummy = dev_get_drvdata(&spi->dev);
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dev_info(&spi->dev, "removing dummy SPI device\n");
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device_remove_file(&spi->dev, &dev_attr_looptest);
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dev_set_drvdata(&spi->dev, NULL);
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static struct spi_driver pl022_dummy_driver = {
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.owner = THIS_MODULE,
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.probe = pl022_dummy_probe,
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.remove = __devexit_p(pl022_dummy_remove),
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static int __init pl022_init_dummy(void)
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return spi_register_driver(&pl022_dummy_driver);
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static void __exit pl022_exit_dummy(void)
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spi_unregister_driver(&pl022_dummy_driver);
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module_init(pl022_init_dummy);
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module_exit(pl022_exit_dummy);
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MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
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MODULE_DESCRIPTION("PL022 SSP/SPI DUMMY Linux driver");
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MODULE_LICENSE("GPL");