refactor(st-ddr): move basic tests in a dedicated file

These basic tests are generic and should be used independently of the
driver, depending on the plaftorm characteristics.

Change-Id: I38161b659ef2a23fd30a56e1c9b1bd98461a2fe4
Signed-off-by: Nicolas Le Bayon <nicolas.le.bayon@foss.st.com>

drivers/st/ddr/stm32mp_ddr_test.c

@@ -0,0 +1,147 @@
+/*
+ * Copyright (C) 2022, STMicroelectronics - All Rights Reserved
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <drivers/st/stm32mp_ddr_test.h>
+#include <lib/mmio.h>
+
+#include <platform_def.h>
+
+#define DDR_PATTERN	0xAAAAAAAAU
+#define DDR_ANTIPATTERN	0x55555555U
+
+/*******************************************************************************
+ * This function tests a simple read/write access to the DDR.
+ * Note that the previous content is restored after test.
+ * Returns 0 if success, and address value else.
+ ******************************************************************************/
+uint32_t stm32mp_ddr_test_rw_access(void)
+{
+	uint32_t saved_value = mmio_read_32(STM32MP_DDR_BASE);
+
+	mmio_write_32(STM32MP_DDR_BASE, DDR_PATTERN);
+
+	if (mmio_read_32(STM32MP_DDR_BASE) != DDR_PATTERN) {
+		return (uint32_t)STM32MP_DDR_BASE;
+	}
+
+	mmio_write_32(STM32MP_DDR_BASE, saved_value);
+
+	return 0U;
+}
+
+/*******************************************************************************
+ * This function tests the DDR data bus wiring.
+ * This is inspired from the Data Bus Test algorithm written by Michael Barr
+ * in "Programming Embedded Systems in C and C++" book.
+ * resources.oreilly.com/examples/9781565923546/blob/master/Chapter6/
+ * File: memtest.c - This source code belongs to Public Domain.
+ * Returns 0 if success, and address value else.
+ ******************************************************************************/
+uint32_t stm32mp_ddr_test_data_bus(void)
+{
+	uint32_t pattern;
+
+	for (pattern = 1U; pattern != 0U; pattern <<= 1U) {
+		mmio_write_32(STM32MP_DDR_BASE, pattern);
+
+		if (mmio_read_32(STM32MP_DDR_BASE) != pattern) {
+			return (uint32_t)STM32MP_DDR_BASE;
+		}
+	}
+
+	return 0;
+}
+
+/*******************************************************************************
+ * This function tests the DDR address bus wiring.
+ * This is inspired from the Data Bus Test algorithm written by Michael Barr
+ * in "Programming Embedded Systems in C and C++" book.
+ * resources.oreilly.com/examples/9781565923546/blob/master/Chapter6/
+ * File: memtest.c - This source code belongs to Public Domain.
+ * size: size in bytes of the DDR memory device.
+ * Returns 0 if success, and address value else.
+ ******************************************************************************/
+uint32_t stm32mp_ddr_test_addr_bus(uint64_t size)
+{
+	uint64_t addressmask = size - 1U;
+	uint64_t offset;
+	uint64_t testoffset = 0U;
+
+	/* Write the default pattern at each of the power-of-two offsets. */
+	for (offset = sizeof(uint32_t); (offset & addressmask) != 0U;
+	     offset <<= 1U) {
+		mmio_write_32(STM32MP_DDR_BASE + (uint32_t)offset,
+			      DDR_PATTERN);
+	}
+
+	/* Check for address bits stuck high. */
+	mmio_write_32(STM32MP_DDR_BASE + (uint32_t)testoffset,
+		      DDR_ANTIPATTERN);
+
+	for (offset = sizeof(uint32_t); (offset & addressmask) != 0U;
+	     offset <<= 1U) {
+		if (mmio_read_32(STM32MP_DDR_BASE + (uint32_t)offset) !=
+		    DDR_PATTERN) {
+			return (uint32_t)(STM32MP_DDR_BASE + offset);
+		}
+	}
+
+	mmio_write_32(STM32MP_DDR_BASE + (uint32_t)testoffset, DDR_PATTERN);
+
+	/* Check for address bits stuck low or shorted. */
+	for (testoffset = sizeof(uint32_t); (testoffset & addressmask) != 0U;
+	     testoffset <<= 1U) {
+		mmio_write_32(STM32MP_DDR_BASE + (uint32_t)testoffset,
+			      DDR_ANTIPATTERN);
+
+		if (mmio_read_32(STM32MP_DDR_BASE) != DDR_PATTERN) {
+			return STM32MP_DDR_BASE;
+		}
+
+		for (offset = sizeof(uint32_t); (offset & addressmask) != 0U;
+		     offset <<= 1) {
+			if ((mmio_read_32(STM32MP_DDR_BASE +
+					  (uint32_t)offset) != DDR_PATTERN) &&
+			    (offset != testoffset)) {
+				return (uint32_t)(STM32MP_DDR_BASE + offset);
+			}
+		}
+
+		mmio_write_32(STM32MP_DDR_BASE + (uint32_t)testoffset,
+			      DDR_PATTERN);
+	}
+
+	return 0U;
+}
+
+/*******************************************************************************
+ * This function checks the DDR size. It has to be run with Data Cache off.
+ * This test is run before data have been put in DDR, and is only done for
+ * cold boot. The DDR data can then be overwritten, and it is not useful to
+ * restore its content.
+ * Returns DDR computed size.
+ ******************************************************************************/
+uint32_t stm32mp_ddr_check_size(void)
+{
+	uint32_t offset = sizeof(uint32_t);
+
+	mmio_write_32(STM32MP_DDR_BASE, DDR_PATTERN);
+
+	while (offset < STM32MP_DDR_MAX_SIZE) {
+		mmio_write_32(STM32MP_DDR_BASE + offset, DDR_ANTIPATTERN);
+		dsb();
+
+		if (mmio_read_32(STM32MP_DDR_BASE) != DDR_PATTERN) {
+			break;
+		}
+
+		offset <<= 1U;
+	}
+
+	INFO("Memory size = 0x%x (%u MB)\n", offset, offset / (1024U * 1024U));
+
+	return offset;
+}