spi: add loopback test driver to allow for spi_master regression tests

/*

 *  linux/drivers/spi/spi-test.h

 *

 *  (c) Martin Sperl <kernel@martin.sperl.org>

 *

 *  spi_test definitions

 *

 *  This program is free software; you can redistribute it and/or modify

 *  it under the terms of the GNU General Public License as published by

 *  the Free Software Foundation; either version 2 of the License, or

 *  (at your option) any later version.

 *

 *  This program is distributed in the hope that it will be useful,

 *  but WITHOUT ANY WARRANTY; without even the implied warranty of

 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 *  GNU General Public License for more details.

 */

#include <linux/spi/spi.h>

#define SPI_TEST_MAX_TRANSFERS 4

#define SPI_TEST_MAX_SIZE (32 * PAGE_SIZE)

#define SPI_TEST_MAX_ITERATE 16

/* the "dummy" start addresses used in spi_test

 * these addresses get translated at a later stage

 */

#define RX_START	BIT(30)

#define TX_START	BIT(31)

#define RX(off)		((void *)(RX_START + off))

#define TX(off)		((void *)(TX_START + off))

/* some special defines for offsets */

#define SPI_TEST_MAX_SIZE_HALF	BIT(29)

/* detection pattern for unfinished reads...

 * - 0x00 or 0xff could be valid levels for tx_buf = NULL,

 * so we do not use either of them

 */

#define SPI_TEST_PATTERN_UNWRITTEN 0xAA

#define SPI_TEST_PATTERN_DO_NOT_WRITE 0x55

#define SPI_TEST_CHECK_DO_NOT_WRITE 64

/**

 * struct spi_test - describes a specific (set of) tests to execute

 *

 * @description:      description of the test

 *

 * @msg:              a template @spi_message usedfor the default settings

 * @transfers:        array of @spi_transfers that are part of the

 *                    resulting spi_message. The first transfer with len == 0

 *                    signifies the end of the list

 * @transfer_count:   normally computed number of transfers with len > 0

 *

 * @run_test:         run a specific spi_test - this allows to override

 *                    the default implementation of @spi_test_run_transfer

 *                    either to add some custom filters for a specific test

 *                    or to effectively run some very custom tests...

 * @execute_msg:      run the spi_message for real - this allows to override

 *                    @spi_test_execute_msg to apply final modifications

 *                    on the spi_message

 * @expected_return:  the expected return code - in some cases we want to

 *                    test also for error conditions

 *

 * @iterate_len:      list of length to iterate on (in addition to the

 *                    explicitly set @spi_transfer.len)

 * @iterate_tx_align: change the alignment of @spi_transfer.tx_buf

 *                    for all values in the below range if set.

 *                    the ranges are:

 *                    [0 : @spi_master.dma_alignment[ if set

 *                    [0 : iterate_tx_align[ if unset

 * @iterate_rx_align: change the alignment of @spi_transfer.rx_buf

 *                    see @iterate_tx_align for details

 * @iterate_transfer_mask: the bitmask of transfers to which the iterations

 *                         apply - if 0, then it applies to all transfer

 *

 * @fill_option:      define the way how tx_buf is filled

 * @fill_pattern:     fill pattern to apply to the tx_buf

 *                    (used in some of the @fill_options)

 */

struct spi_test {

	char description[64];

	struct spi_message msg;

	struct spi_transfer transfers[SPI_TEST_MAX_TRANSFERS];

	unsigned int transfer_count;

	int (*run_test)(struct spi_device *spi, struct spi_test *test,

			void *tx, void *rx);

	int (*execute_msg)(struct spi_device *spi, struct spi_test *test,

			   void *tx, void *rx);

	int expected_return;

	/* iterate over all the non-zero values */

	int iterate_len[SPI_TEST_MAX_ITERATE];

	int iterate_tx_align;

	int iterate_rx_align;

	u32 iterate_transfer_mask;

	/* the tx-fill operation */

	u32 fill_option;

#define FILL_MEMSET_8	0	/* just memset with 8 bit */

#define FILL_MEMSET_16	1	/* just memset with 16 bit */

#define FILL_MEMSET_24	2	/* just memset with 24 bit */

#define FILL_MEMSET_32	3	/* just memset with 32 bit */

#define FILL_COUNT_8	4	/* fill with a 8 byte counter */

#define FILL_COUNT_16	5	/* fill with a 16 bit counter */

#define FILL_COUNT_24	6	/* fill with a 24 bit counter */

#define FILL_COUNT_32	7	/* fill with a 32 bit counter */

#define FILL_TRANSFER_BYTE_8  8	/* fill with the transfer byte - 8 bit */

#define FILL_TRANSFER_BYTE_16 9	/* fill with the transfer byte - 16 bit */

#define FILL_TRANSFER_BYTE_24 10 /* fill with the transfer byte - 24 bit */

#define FILL_TRANSFER_BYTE_32 11 /* fill with the transfer byte - 32 bit */

#define FILL_TRANSFER_NUM     16 /* fill with the transfer number */

	u32 fill_pattern;

};

/* default implementation for @spi_test.run_test */

int spi_test_run_test(struct spi_device *spi,

		      const struct spi_test *test,

		      void *tx, void *rx);

/* default implementation for @spi_test.execute_msg */

int spi_test_execute_msg(struct spi_device *spi,

			 struct spi_test *test,

			 void *tx, void *rx);

/* function to execute a set of tests */

int spi_test_run_tests(struct spi_device *spi,

		       struct spi_test *tests);

/* some of the default @spi_transfer.len to test */

#define ITERATE_LEN 16, 32, 64, 128, 256, 1024, PAGE_SIZE, 65536

#define ITERATE_MAX_LEN ITERATE_LEN, SPI_TEST_MAX_SIZE

/* the default alignment to test */

#define ITERATE_ALIGN sizeof(int)