arm64/imx9: Add DMA memory allocator

Add a simple allocator for DMA safe memory. It will provide contiguous
blocks of memory with D-Cache line size alignment.

NOTE: The optimal granule size is the D-Cache line size (64), but due
to restrictions in the granule allocator this would result in a maximum
block size of 2K only, thus use 256B granules instead givin 8K max block
size.

Once the granule allocator is fixed this limitation can be removed.

arch/arm64/src/imx9/Kconfig

@@ -24,6 +24,24 @@ endchoice # i.MX9 Chip Selection
 
 endmenu # "i.MX9 Chip Selection"
 
+config IMX9_DMA_ALLOC
+	bool "Enable DMA capable memory allocator"
+	depends on GRAN
+	default y if CONFIG_FAT_DMAMEMORY
+
+menu "DMA Allocator Configuration"
+	depends on IMX9_DMA_ALLOC
+
+config IMX9_DMA_ALLOC_POOL_SIZE
+	int "DMA allocator memory pool size in bytes"
+	default 4096
+
+config IMX9_DMA_ALLOC_SECT
+	string "Section for DMA allocator memory pool, default is .bss"
+	default ".bss"
+
+endmenu # DMA Allocator Configuration
+
 config IMX9_FLEXIO_PWM
 	bool
 	select PWM_MULTICHAN

arch/arm64/src/imx9/Make.defs

@@ -55,3 +55,7 @@ endif
 ifeq ($(CONFIG_IMX9_EDMA), y)
   CHIP_CSRCS += imx9_edma.c
 endif
+
+ifeq ($(CONFIG_IMX9_DMA_ALLOC),y)
+  CHIP_CSRCS += imx9_dma_alloc.c
+endif

arch/arm64/src/imx9/imx9_dma_alloc.c

@@ -0,0 +1,145 @@
+/****************************************************************************
+ * arch/arm64/src/imx9/imx9_dma_alloc.c
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <syslog.h>
+#include <stdint.h>
+#include <errno.h>
+
+#include <nuttx/mm/gran.h>
+
+#include <chip.h>
+
+#if defined(CONFIG_IMX9_DMA_ALLOC)
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/* DMA buffers must be aligned with the D-Cache line boundaries to facilitate
+ * cache operations on the DMA buffers when the D-Cache is enabled.
+ */
+
+#define DMA_ALIGN       ARMV8A_DCACHE_LINESIZE
+#define DMA_ALIGN_MASK  (DMA_ALIGN - 1)
+#define DMA_ALIGN_UP(n) (((n) + DMA_ALIGN_MASK) & ~DMA_ALIGN_MASK)
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+static GRAN_HANDLE dma_allocator;
+
+/* The DMA heap size constrains the total number of things that can be
+ * ready to do DMA at a time.
+ *
+ * For example, FAT DMA depends on one sector-sized buffer per filesystem
+ * plus one sector-sized buffer per file.
+ *
+ * We use a fundamental alignment / granule size of 64B; it fulfills the
+ * requirement for any DMA engine.
+ */
+
+static uint8_t g_dma_heap[CONFIG_IMX9_DMA_ALLOC_POOL_SIZE]
+aligned_data(DMA_ALIGN) locate_data(CONFIG_IMX9_DMA_ALLOC_SECT);
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: imx9_dma_alloc_init
+ *
+ * Description:
+ *   Initialize the DMA memory allocator.
+ *
+ * Returned Value:
+ *   Zero (OK) is returned on success; a negated errno value is returned
+ *   on failure.
+ *
+ ****************************************************************************/
+
+int imx9_dma_alloc_init(void)
+{
+  /* Allocate 64B granules with 64B alignment */
+
+  /* REVISIT: Use 256B granule size to get 8K maximum allocation. This is a
+   * limitation in the granule allocator itself.
+   */
+
+  dma_allocator = gran_initialize(g_dma_heap, sizeof(g_dma_heap), 8, 6);
+
+  if (dma_allocator == NULL)
+    {
+      return -ENOMEM;
+    }
+
+  return OK;
+}
+
+/****************************************************************************
+ * Name: imx9_dma_alloc
+ *
+ * Description:
+ *   Allocate a contiguous block of physical memory for DMA.
+ *
+ * Input Parameters:
+ *   size - Size of the requested block in bytes.
+ *
+ * Returned Value:
+ *   Physical address of the first page on success; NULL on failure.
+ *
+ ****************************************************************************/
+
+void *imx9_dma_alloc(size_t size)
+{
+  return gran_alloc(dma_allocator, size);
+}
+
+/****************************************************************************
+ * Name: imx9_dma_free
+ *
+ * Description:
+ *   Free a previously allocated DMA memory block.
+ *
+ * Input Parameters:
+ *   memory - Physical address of the first page of DMA memory.
+ *   size   - Size of the allocated block in bytes.
+ *
+ * Returned Value:
+ *   None.
+ *
+ ****************************************************************************/
+
+void imx9_dma_free(void *memory, size_t size)
+{
+  gran_free(dma_allocator, memory, size);
+}
+
+#endif /* CONFIG_IMX9_DMA_ALLOC */

arch/arm64/src/imx9/imx9_dma_alloc.h

@@ -0,0 +1,88 @@
+/****************************************************************************
+ * arch/arm64/src/imx9/imx9_dma_alloc.h
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+#ifndef __ARCH_ARM64_SRC_IMX9_IMX9_DMA_ALLOC_H
+#define __ARCH_ARM64_SRC_IMX9_IMX9_DMA_ALLOC_H
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdint.h>
+
+/****************************************************************************
+ * Public Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: imx9_dma_alloc_init
+ *
+ * Description:
+ *   Initialize the DMA memory allocator.
+ *
+ * Returned Value:
+ *   Zero (OK) is returned on success; a negated errno value is returned
+ *   on failure.
+ *
+ ****************************************************************************/
+
+int imx9_dma_alloc_init(void);
+
+/****************************************************************************
+ * Name: imx9_dma_alloc
+ *
+ * Description:
+ *   Allocate a contiguous block of physical memory for DMA.
+ *
+ * Input Parameters:
+ *   size - Size of the requested block in bytes.
+ *
+ * Returned Value:
+ *   Physical address of the first page on success; NULL on failure.
+ *
+ ****************************************************************************/
+
+void *imx9_dma_alloc(size_t size);
+
+/****************************************************************************
+ * Name: imx9_dma_free
+ *
+ * Description:
+ *   Free a previously allocated DMA memory block.
+ *
+ * Input Parameters:
+ *   memory - Physical address of the first page of DMA memory.
+ *   size   - Size of the allocated block in bytes.
+ *
+ * Returned Value:
+ *   None.
+ *
+ ****************************************************************************/
+
+void imx9_dma_free(void *memory, size_t size);
+
+#ifdef CONFIG_FAT_DMAMEMORY
+#  define fat_dma_alloc(s)  imx9_dma_alloc(s)
+#  define fat_dma_free(m,s) imx9_dma_free(m,s)
+#endif
+
+#endif /* __ARCH_ARM64_SRC_IMX9_IMX9_DMA_ALLOC_H */

boards/arm64/imx9/imx93-evk/configs/nsh/defconfig

@@ -26,11 +26,15 @@ CONFIG_EXAMPLES_HELLO=y
 CONFIG_EXPERIMENTAL=y
 CONFIG_FS_PROCFS=y
 CONFIG_FS_ROMFS=y
+CONFIG_GRAN=y
 CONFIG_HAVE_CXX=y
 CONFIG_HAVE_CXXINITIALIZE=y
 CONFIG_I2C=y
 CONFIG_I2C_RESET=y
 CONFIG_IDLETHREAD_STACKSIZE=8192
+CONFIG_IMX9_DMA_ALLOC=y
+CONFIG_IMX9_DMA_ALLOC_POOL_SIZE=81920
+CONFIG_IMX9_DMA_ALLOC_SECT=".bss"
 CONFIG_IMX9_EDMA=y
 CONFIG_IMX9_FLEXIO1_PWM=y
 CONFIG_IMX9_GPIO_IRQ=y

boards/arm64/imx9/imx93-evk/src/imx9_bringup.c

@@ -29,6 +29,8 @@
 
 #include <nuttx/fs/fs.h>
 
+#include "imx9_dma_alloc.h"
+
 #include "imx93-evk.h"
 
 /****************************************************************************
@@ -57,6 +59,16 @@ int imx9_bringup(void)
     }
 #endif
 
+#ifdef CONFIG_IMX9_DMA_ALLOC
+  /* Initialize the DMA memory allocator */
+
+  ret = imx9_dma_alloc_init();
+  if (ret < 0)
+    {
+      syslog(LOG_ERR, "ERROR: Failed initialize DMA allocator: %d\n", ret);
+    }
+#endif
+
 #ifdef CONFIG_PWM
   /* Configure PWM outputs */