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driver/mem:add Mem Driver.
Signed-off-by: yangguangcai <[email protected]>
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‎Documentation/components/drivers/special/devmem.rst

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==============
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DEVMEM Drivers
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==============
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The `devmem` driver provides an interface for accessing memory-mapped
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I/O in an embedded system. This driver allows for reading, writing, and
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memory mapping of specific memory regions or device registers.
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``read()``: This function reads data from the memory-mapped I/O address
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space into the buffer provided by the caller. The first byte read
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corresponds to the address specified by the device's "current memory
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address". The addresses for subsequent bytes depend on the auto-increment
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behavior of the specific device.
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``write()``: This function transfers data from the provided data buffer by
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the caller to the memory-mapped I/O address space. The first byte written
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corresponds to the address specified by the device's "current memory address".
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``mmap()``: The `mmap()` function provides a mechanism to map a device's
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memory region into the user space, allowing direct access to device
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registers or memory regions. The mapped region can be accessed using
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normal memory operations.
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The function requires a base address and size for the memory region
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to be mapped. If successful, it returns a pointer to the mapped region.
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If mapping fails, it returns `EINVAL` and `errno` is set appropriately.

‎Documentation/components/drivers/special/index.rst

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audio.rst
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clk.rst
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devicetree.rst
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devmem.rst
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dma.rst
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framebuffer.rst
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i2c.rst

‎drivers/drivers_initialize.c

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@@ -129,6 +129,10 @@ void drivers_initialize(void)
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devzero_register(); /* Standard /dev/zero */
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#endif
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#ifdef CONFIG_DEV_MEM
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devmem_register();
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#endif
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#if defined(CONFIG_DEV_LOOP)
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loop_register(); /* Standard /dev/loop */
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#endif

‎drivers/misc/Kconfig

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@@ -15,6 +15,13 @@ config DEV_ZERO
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bool "Enable /dev/zero"
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default n
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config DEV_MEM
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bool "Enable /dev/mem"
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default n
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---help---
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It is a full image of physical memory and can be used to
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access physical memory.
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config DEV_ASCII
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bool "Enable /dev/ascii"
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default n

‎drivers/misc/Make.defs

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@@ -30,6 +30,10 @@ ifeq ($(CONFIG_DEV_ZERO),y)
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CSRCS += dev_zero.c
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endif
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ifeq ($(CONFIG_DEV_MEM),y)
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CSRCS += dev_mem.c
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endif
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ifeq ($(CONFIG_DEV_ASCII),y)
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CSRCS += dev_ascii.c
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endif

‎drivers/misc/dev_mem.c

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/****************************************************************************
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* drivers/misc/dev_mem.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/drivers/drivers.h>
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#include <nuttx/kmalloc.h>
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#include <nuttx/memoryregion.h>
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#include <sys/param.h>
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#include <sys/mman.h>
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/****************************************************************************
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* Pre-processor Definitions
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****************************************************************************/
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#define DEVMEM_REGION 8
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/****************************************************************************
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* Public Data
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****************************************************************************/
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extern uint8_t _stext[]; /* Start of .text */
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extern uint8_t _etext[]; /* End_1 of .text + .rodata */
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extern uint8_t _sdata[]; /* Start of .data */
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extern uint8_t _edata[]; /* End+1 of .data */
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extern uint8_t _sbss[]; /* Start of .bss */
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extern uint8_t _ebss[]; /* End+1 of .bss */
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/****************************************************************************
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* Private Function Prototypes
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****************************************************************************/
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/* Character driver methods */
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static ssize_t devmem_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen);
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static ssize_t devmem_write(FAR struct file *filep, FAR const char *buffer,
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size_t buflen);
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static int devmem_mmap(FAR struct file *filep,
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FAR struct mm_map_entry_s *map);
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/****************************************************************************
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* Private Data
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****************************************************************************/
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static const struct file_operations g_devmem_fops =
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{
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NULL, /* open */
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NULL, /* close */
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devmem_read, /* read */
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devmem_write, /* write */
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NULL, /* seek */
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NULL, /* ioctl */
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devmem_mmap, /* mmap */
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};
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/****************************************************************************
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* Private Functions
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****************************************************************************/
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/****************************************************************************
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* Name: devmem_read
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****************************************************************************/
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static ssize_t devmem_read(FAR struct file *filep, FAR char *buffer,
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size_t buflen)
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{
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FAR struct memory_region_s *region = filep->f_inode->i_private;
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uintptr_t src = filep->f_pos;
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uintptr_t start;
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uintptr_t end;
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ssize_t len;
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int i;
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DEBUGASSERT(region && src);
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for (i = 0; i < DEVMEM_REGION; i++)
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{
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if (region[i].start == 0 && region[i].end == 0)
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{
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break;
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}
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start = MAX(src, region[i].start);
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end = MIN(src + buflen, region[i].end);
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len = end - start;
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if (len > 0 && (region[i].flags & PROT_READ))
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{
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memcpy(buffer, (FAR const void *)start, len);
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return len;
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}
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}
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return -EINVAL;
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}
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/****************************************************************************
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* Name: devmem_write
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****************************************************************************/
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static ssize_t devmem_write(FAR struct file *filep, FAR const char *buffer,
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size_t buflen)
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{
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FAR struct memory_region_s *region = filep->f_inode->i_private;
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uintptr_t dest = filep->f_pos;
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uintptr_t start;
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uintptr_t end;
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ssize_t len;
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int i;
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DEBUGASSERT(region && dest);
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for (i = 0; i < DEVMEM_REGION; i++)
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{
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if (region[i].start == 0 && region[i].end == 0)
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{
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break;
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}
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start = MAX(dest, region[i].start);
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end = MIN(dest + buflen, region[i].end);
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len = end - start;
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if (len > 0 && (region[i].flags & PROT_WRITE))
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{
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memcpy((FAR void *)start, buffer, len);
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return len;
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}
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}
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return -EINVAL;
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}
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/****************************************************************************
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* Name: devmem_mmap
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****************************************************************************/
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static int devmem_mmap(FAR struct file *filep,
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FAR struct mm_map_entry_s *map)
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{
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FAR struct memory_region_s *region = filep->f_inode->i_private;
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uintptr_t start;
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uintptr_t end;
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int i;
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DEBUGASSERT(region);
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if (map->offset < 0)
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{
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return -EINVAL;
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}
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start = map->offset;
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end = start + map->length;
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for (i = 0; i < DEVMEM_REGION; i++)
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{
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if (region[i].start == 0 && region[i].end == 0)
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{
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break;
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}
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if (start >= region[i].start && end <= region[i].end)
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{
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map->vaddr = (FAR void *)start;
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return 0;
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}
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}
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return -EINVAL;
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}
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: devmem_register
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*
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* Description:
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* Create an MEM driver.
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*
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* Returned Value:
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* Zero (OK) on success; A negated errno value on failure.
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*
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****************************************************************************/
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int devmem_register(void)
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{
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FAR struct memory_region_s *region;
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bool merge = (_edata == _sbss);
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ssize_t len = 0;
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int ret;
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region = kmm_calloc(DEVMEM_REGION, sizeof(*region));
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if (region == NULL)
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{
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return -ENOMEM;
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}
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#ifdef CONFIG_BOARD_MEMORY_RANGE
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len = parse_memory_region(CONFIG_BOARD_MEMORY_RANGE, region,
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DEVMEM_REGION - 1);
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if (len < 0)
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{
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kmm_free(region);
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return len;
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}
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#endif
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if (len + (4 - merge) > DEVMEM_REGION)
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{
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len = DEVMEM_REGION - (4 - merge);
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}
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region[len].flags = PROT_EXEC | PROT_READ;
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region[len].start = (uintptr_t)_stext;
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region[len++].end = (uintptr_t)_etext;
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region[len].flags = PROT_WRITE | PROT_READ;
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region[len].start = (uintptr_t)_sdata;
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region[len++].end = (uintptr_t)_edata;
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if (merge)
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{
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region[len - 1].end = (uintptr_t)_ebss;
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}
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else
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{
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region[len].flags = PROT_WRITE | PROT_READ;
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region[len].start = (uintptr_t)_sbss;
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region[len++].end = (uintptr_t)_ebss;
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}
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/* register the new MEM driver */
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ret = register_driver("/dev/mem", &g_devmem_fops, 0666, region);
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if (ret < 0)
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{
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kmm_free(region);
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return -ENOMEM;
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}
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return ret;
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}

‎include/nuttx/drivers/drivers.h

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void devcrypto_register(void);
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/****************************************************************************
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* Name: devmem_register
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*
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* Description:
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* Register devmem driver
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*
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****************************************************************************/
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#ifdef CONFIG_DEV_MEM
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int devmem_register(void);
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#endif
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/****************************************************************************
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* Name: devzero_register
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*

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