How can I prevent the contents of "RETRAM" from being erased? (base on linux with m4 rproc)
Hi all.
I want to prevent the contents of "RETRAM" from being erased when I run the firmware with m4 rproc on "OpenSTLinux".
"RETRAM" is powered by the battery through the VBAT pin to maintain data.
To this end, TF-A was also modified to set and maintain the value of "PWR_CR2_RREN" in the "PWR_CR2" registry.
In the "Engineering Mode" where M4 Firmware can be run on its own, "RETRAM" data is well maintained. However, when you boot into "OpenSTLinux" and load the firmware into M4 rproc and debug it, the contents of "RETRAM" are initialized.
The following is the contents of the "RETRAM" related ld file.
MEMORY
{
m_interrupts (RX) : ORIGIN = 0x00000000, LENGTH = 0x00000298
m_retram (RWX) : ORIGIN = 0x00000400, LENGTH = 0x0000FC00
m_text (RX) : ORIGIN = 0x10000000, LENGTH = 0x00030000
m_data (RW) : ORIGIN = 0x10030000, LENGTH = 0x00010000
m_ipc_shm (RW) : ORIGIN = 0x10040000, LENGTH = 0x00008000
}
SECTIONS
{
.retram (NOLOAD) :
{
. = ALIGN(4);
*(.m_retram)
_eretram = .;
} > m_retram
}
The following variables are declared in the "RETRAM" area:
__IO uint8_t G_RETRAM[0xFC00] __attribute ((section(".m_retram")));
The following are the contents of the DTS file related to "RETRAM".
reserved-memory {
#address-cells = <1>;
#size-cells = <1>;
ranges;
retram: retram@0x38000000 {
compatible = "shared-dma-pool";
/*
reg = <0x38000000 0x10000>;
*/
reg = <0x38000000 0x3FF>;
no-map;
};
retram_bat: retram_bat@0x38000400 {
reg = <0x38000400 0xFC00>;
no-map;
};
.........
}
&m4_rproc {
memory-region = <&retram>, <&retram_bat>, <&mcuram>, <&mcuram2>, <&vdev0vring0>,
<&vdev0vring1>, <&vdev0buffer>;
mboxes = <&ipcc 0>, <&ipcc 1>, <&ipcc 2>;
mbox-names = "vq0", "vq1", "shutdown";
interrupt-parent = <&exti>;
interrupts = <68 1>;
interrupt-names = "wdg";
wakeup-source;
recovery;
status = "okay";
};
Please give me a lot of advice.
Thanks.
Regards
Machilus