xiaoxiang781216 commented on code in PR #16687:
URL: https://github.com/apache/nuttx/pull/16687#discussion_r2191461543
##########
arch/avr/src/avr/Kconfig:
##########
@@ -94,8 +110,76 @@ config AVR_HAS_MEMX_PTR
pointers in arbitrary interaction with the kernel. Not all API
functions have these qualifiers added to their parameters.
+config AVR_HAS_FLMAP
+ bool "Use memory-mapped access to flash"
+ depends on AVR_BOARD_HAS_FLMAP && AVR_CHIP_HAS_FLMAP
+ ---help---
+ Newer AVR chips - namely tinyAVR and AVR families - have (part
of)
+ their program memory (flash) mapped into data memory address
space.
+ The mapping is limited to 32kB window.
+
+ With this option enabled, const variables are kept in the
program
+ memory and no copy to RAM is done. Yet it is still possible to
use
+ such variables in any interaction with the kernel as they are
+ visible in data memory address space.
+
+ Note that this option only triggers some basic configuration
+ in the init function. It is the linker script of the board that
needs
+ to ensure variables are placed correctly.
+
+ Beware that FLMAP bits in NVMCTRL.CTRLB I/O register which
select
+ the segment of program memory to be mapped may not be changed
freely
+ by the application. If the application needs to change the
mapping,
+ it may only do so while observing these rules:
+
+ 1. No kernel function must be called until the original value
+ is restored.
+
+ 2. Interrupts must be disabled for as long as the value is
changed.
+
+endchoice # Const variable placement
+
+config AVR_FLMAP_RODATA_SIZE
+ int "Size of .rodata FLMAP section"
+ depends on AVR_HAS_FLMAP
+ default 4096
+ ---help---
+ Specify size of .rodata memory section, ie. the section that
stores
+ const variables. This will be passed as a parameter to the
linker
+ to be used by the board's linker script.
+
+ Value must be divisible by 512 and no more than 32 kilobytes
+ is possible.
+
+config AVR_FLMAP_RODATA_OFFSET
+ int "Offset of .rodata FLMAP section"
+ depends on AVR_HAS_FLMAP
+ default 0
+ ---help---
+ Specify size of memory block between end of the .rodata section
+ (counting its full size as defined in AVR_FLMAP_RODATA_SIZE)
+ and the end of flash.
+
+ This value is intended to leave the end of the flash unused,
+ presumably for the purpose of placing APPDATA section in there
+ (see the chip documentation for details about subdividing
+ the program flash to BOOT, APPCODE and APPDATA sections.)
+
+ Note that this value is only passed to the linker to be used
+ by the linker script - the script then needs to place
+ the .rodata section accordingly.
+
+ Value must be divisible by 512 and no more than 31 kilobytes
+ is possible. Sum of this value and AVR_FLMAP_RODATA_SIZE must
+ also not exceed 32kB.
config AVR_HAS_RAMPZ
bool
+config AVR_BOARD_HAS_FLMAP
Review Comment:
`AVR_HAVE_BOARD_FLMAP`
##########
arch/avr/src/avrdx/avrdx_head.S:
##########
@@ -492,6 +492,57 @@ __start:
out _SFR_IO_ADDR(SPH), r29
out _SFR_IO_ADDR(SPL), r28
+
+#ifdef AVR_HAS_FLMAP
+
+ /* Configure FLMAP bits in NVMCTRL.CTRLB in case this was software
+ * reset and they are not in default state.
+ *
+ * Don't care if the application actually changes the register. These
+ * bits are not under configuration protection (CCP) and runaway
+ * application can possibly change them.
+ */
+
+ ldi r26, lo8(NVMCTRL_CTRLB)
+ ldi r27, hi8(NVMCTRL_CTRLB)
+ ld r16, X
+
+ /* Default value (on current chips anyway) uses all bits set to one. */
+
+# if !defined(NVMCTRL_FLMAP_1_bm)
+
+ /* Might be there won't be such (supported) device ever. */
+
+# error Chips without FLMAP bit 1 are not supported
+
+# elif !defined(NVMCTRL_FLMAP_2_bm)
+
+ /* Expected case */
+
+ ldi r17, NVMCTRL_FLMAP_0_bm | NVMCTRL_FLMAP_1_bm;
+
+# else
+
+ /* Future device with more than 128kB RAM. The default is expected
+ * to be all bits set to one but it needs to be verified when
+ * support for such chip is added. Issue a warning.
+ */
+
+# warning Support for more than 128kB flash was done blindly here
+
+ ldi r17, NVMCTRL_FLMAP_0_bm | NVMCTRL_FLMAP_1_bm |
NVMCTRL_FLMAP_2_bm;
+
+#endif
Review Comment:
`# endif`
##########
arch/avr/src/avr/Kconfig:
##########
@@ -94,8 +110,76 @@ config AVR_HAS_MEMX_PTR
pointers in arbitrary interaction with the kernel. Not all API
functions have these qualifiers added to their parameters.
+config AVR_HAS_FLMAP
+ bool "Use memory-mapped access to flash"
+ depends on AVR_BOARD_HAS_FLMAP && AVR_CHIP_HAS_FLMAP
+ ---help---
+ Newer AVR chips - namely tinyAVR and AVR families - have (part
of)
+ their program memory (flash) mapped into data memory address
space.
+ The mapping is limited to 32kB window.
+
+ With this option enabled, const variables are kept in the
program
+ memory and no copy to RAM is done. Yet it is still possible to
use
+ such variables in any interaction with the kernel as they are
+ visible in data memory address space.
+
+ Note that this option only triggers some basic configuration
+ in the init function. It is the linker script of the board that
needs
+ to ensure variables are placed correctly.
+
+ Beware that FLMAP bits in NVMCTRL.CTRLB I/O register which
select
+ the segment of program memory to be mapped may not be changed
freely
+ by the application. If the application needs to change the
mapping,
+ it may only do so while observing these rules:
+
+ 1. No kernel function must be called until the original value
+ is restored.
+
+ 2. Interrupts must be disabled for as long as the value is
changed.
+
+endchoice # Const variable placement
+
+config AVR_FLMAP_RODATA_SIZE
+ int "Size of .rodata FLMAP section"
+ depends on AVR_HAS_FLMAP
+ default 4096
+ ---help---
+ Specify size of .rodata memory section, ie. the section that
stores
+ const variables. This will be passed as a parameter to the
linker
+ to be used by the board's linker script.
+
+ Value must be divisible by 512 and no more than 32 kilobytes
+ is possible.
+
+config AVR_FLMAP_RODATA_OFFSET
+ int "Offset of .rodata FLMAP section"
+ depends on AVR_HAS_FLMAP
+ default 0
+ ---help---
+ Specify size of memory block between end of the .rodata section
+ (counting its full size as defined in AVR_FLMAP_RODATA_SIZE)
+ and the end of flash.
+
+ This value is intended to leave the end of the flash unused,
+ presumably for the purpose of placing APPDATA section in there
+ (see the chip documentation for details about subdividing
+ the program flash to BOOT, APPCODE and APPDATA sections.)
+
+ Note that this value is only passed to the linker to be used
+ by the linker script - the script then needs to place
+ the .rodata section accordingly.
+
+ Value must be divisible by 512 and no more than 31 kilobytes
+ is possible. Sum of this value and AVR_FLMAP_RODATA_SIZE must
+ also not exceed 32kB.
config AVR_HAS_RAMPZ
Review Comment:
may be we need create a new patch to rename _HAS_ to _HAVE_ to align with
ARCH_HAVE_xxx option
##########
arch/avr/src/avr/Kconfig:
##########
@@ -94,8 +110,76 @@ config AVR_HAS_MEMX_PTR
pointers in arbitrary interaction with the kernel. Not all API
functions have these qualifiers added to their parameters.
+config AVR_HAS_FLMAP
+ bool "Use memory-mapped access to flash"
+ depends on AVR_BOARD_HAS_FLMAP && AVR_CHIP_HAS_FLMAP
+ ---help---
+ Newer AVR chips - namely tinyAVR and AVR families - have (part
of)
+ their program memory (flash) mapped into data memory address
space.
+ The mapping is limited to 32kB window.
+
+ With this option enabled, const variables are kept in the
program
+ memory and no copy to RAM is done. Yet it is still possible to
use
+ such variables in any interaction with the kernel as they are
+ visible in data memory address space.
+
+ Note that this option only triggers some basic configuration
+ in the init function. It is the linker script of the board that
needs
+ to ensure variables are placed correctly.
+
+ Beware that FLMAP bits in NVMCTRL.CTRLB I/O register which
select
+ the segment of program memory to be mapped may not be changed
freely
+ by the application. If the application needs to change the
mapping,
+ it may only do so while observing these rules:
+
+ 1. No kernel function must be called until the original value
+ is restored.
+
+ 2. Interrupts must be disabled for as long as the value is
changed.
+
+endchoice # Const variable placement
+
+config AVR_FLMAP_RODATA_SIZE
+ int "Size of .rodata FLMAP section"
+ depends on AVR_HAS_FLMAP
+ default 4096
+ ---help---
+ Specify size of .rodata memory section, ie. the section that
stores
+ const variables. This will be passed as a parameter to the
linker
+ to be used by the board's linker script.
+
+ Value must be divisible by 512 and no more than 32 kilobytes
+ is possible.
+
+config AVR_FLMAP_RODATA_OFFSET
+ int "Offset of .rodata FLMAP section"
+ depends on AVR_HAS_FLMAP
+ default 0
+ ---help---
+ Specify size of memory block between end of the .rodata section
+ (counting its full size as defined in AVR_FLMAP_RODATA_SIZE)
+ and the end of flash.
+
+ This value is intended to leave the end of the flash unused,
+ presumably for the purpose of placing APPDATA section in there
+ (see the chip documentation for details about subdividing
+ the program flash to BOOT, APPCODE and APPDATA sections.)
+
+ Note that this value is only passed to the linker to be used
+ by the linker script - the script then needs to place
+ the .rodata section accordingly.
+
+ Value must be divisible by 512 and no more than 31 kilobytes
+ is possible. Sum of this value and AVR_FLMAP_RODATA_SIZE must
+ also not exceed 32kB.
config AVR_HAS_RAMPZ
bool
+config AVR_BOARD_HAS_FLMAP
+ bool
+
+config AVR_CHIP_HAS_FLMAP
Review Comment:
AVR_HAVE_FLMAP
##########
boards/Kconfig:
##########
@@ -94,6 +94,7 @@ config ARCH_BOARD_AVRDX_BREADXAVR
select ARCH_HAVE_LEDS
select ARCH_HAVE_BUTTONS
select ARCH_HAVE_IRQBUTTONS
+ select AVR_BOARD_HAS_FLMAP
Review Comment:
but this flag is AVR specific should contain AVR term in the config to avoid
the confusion.
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