dma test driver

/*
 * Test SPI DMA
 *
 * Copyright (C) 2020 Cirrus Logic, Inc. and
 *                    Cirrus Logic International Semiconductor Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/err.h>
#include <linux/spi/spi.h>
#include <linux/regmap.h>

#define TEST_SIZE 20428

static struct regmap_config test_spi_regmap = {
	.name = "test_spi",
	.reg_bits = 32,
	.pad_bits = 32,
	.val_bits = 32,
	.reg_stride = 4,

	.max_register = 0xFFFFFFFF,
	.cache_type = REGCACHE_NONE,
};

static int test_spi_probe(struct spi_device *spi)
{
	int i, ret = 0;
	struct regmap *regmap;
	char *buffer;
	char *buffer2;

	pr_info("%s",__func__);

	regmap = devm_regmap_init_spi(spi, &test_spi_regmap);
	if (IS_ERR(regmap)) {
		ret = PTR_ERR(regmap);
		dev_err(&spi->dev, "Failed to allocate register map: %d\n", ret);
	}

	buffer = vmalloc(TEST_SIZE);
	buffer2 = kmalloc(TEST_SIZE, GFP_KERNEL);
	for (i = 0; i < TEST_SIZE; i++){
		buffer[i] = i % 0xff;
		buffer2[i] = i % 0xff;
	}

	regmap_raw_write(regmap, 0, buffer, TEST_SIZE);

	mdelay(50);

	regmap_raw_write(regmap, 0, buffer2, TEST_SIZE);

	kfree(buffer);

	return ret;
}

static const struct of_device_id test_spi_match[] = {
	{ .compatible = "spi-dma-test", },
	{},
};
MODULE_DEVICE_TABLE(of, test_spi_match);

static struct spi_driver test_spi_driver = {
	.driver = {
		.name = "spi-dma-test",
		.of_match_table = test_spi_match,
	},
	.probe = &test_spi_probe,
};

module_spi_driver(test_spi_driver);

MODULE_DESCRIPTION("Test RPI4 SPI BUG");
MODULE_AUTHOR("Lucas Tanure <[email protected]>");
MODULE_LICENSE("GPL v2");



###################################################################################################
Device tree

/dts-v1/;
/plugin/;

/ {
	compatible = "brcm,bcm2835";

	fragment@0 {
		target = <&spi0>;
		__overlay__ {
			#address-cells = <1>;
			#size-cells = <0>;
			status = "okay";

			spidev@1{
				status = "disabled";
			};

			spi_test@1{
				spi-max-frequency = <12500000>;
				reg = <1>;
				compatible = "spi-dma-test";
			};
		};
	};
};