eren-terzioglu opened a new pull request, #18959:
URL: https://github.com/apache/nuttx/pull/18959
## Summary
The HP core can exchange data with a running ULP LP-Core application in two
ways:
* **Global symbols** — read and write ULP variables exported to shared
memory through ``/dev/ulp``.
* **LP Mailbox** — send and receive messages through the hardware mailbox
using ``/dev/lp_mailbox``.
Global symbols already implemented, this PR implements LP Mailbox.
#### LP Mailbox
The ESP32-P4 LP Mailbox provides inter-core communication between the LP and
HP cores.
It exposes sixteen 32-bit message registers that both cores can read and
write.
LP Mailbox is exposed as ``/dev/lp_mailbox`` and uses ``read()`` and
``write()`` to exchange byte-sized messages or ``ioctl(fd, FIOC_NOTIFY,
handler)``
for interrupt callback when a message arrives to communicate with the LP
core.
<!-- This field should contain a summary of the changes. It will be
pre-filled with the commit's message and descriptions. Adjust it accordingly -->
* Docs/platforms/esp32p4: Add LP Mailbox docs
Add LP Mailbox docs for esp32p4
* boards/risc-v/esp32p4: Add LP Mailbox board support
Add LP Mailbox board support for esp32p4
* arch/risc-v/espressif: Add LP Mailbox support for esp32p4
Add LP Mailbox support for esp32p4
## Impact
<!-- Please fill the following sections with YES/NO and provide a brief
explanation -->
Impact on user: Yes, LP Mailbox supported for esp32p4
<!-- Does it impact user's applications? How? -->
Impact on build: No
<!-- Does it impact on building NuttX? How? (please describe the required
changes on the build system) -->
Impact on hardware: Yes, LP Mailbox support added for esp32p4
<!-- Does it impact a specific hardware supported by NuttX? -->
Impact on documentation: Yes, related docs added
<!-- Does it impact the existing documentation? Please provide additional
documentation to reflect that -->
Impact on security: No
<!-- Does it impact NuttX's security? -->
Impact on compatibility: No
<!-- Does it impact compatibility between previous and current versions? Is
this a breaking change? -->
## Testing
<!-- Please provide all the testing procedure. Consider that upstream
reviewers should be able to reproduce the same testing performed internally -->
`esp32p4-function-ev-board:ulp` config used with these options:
```
CONFIG_ESPRESSIF_LP_MAILBOX=y
```
### Building
<!-- Provide how to build the test for each SoC being tested -->
Command to build:
```
make -j distclean && ./tools/configure.sh esp32p4-function-ev-board:ulp &&
kconfig-tweak -e CONFIG_ESPRESSIF_LP_MAILBOX && make olddefconfig -s -j && make
-j && make flash ESPTOOL_PORT=/dev/ttyUSB0
```
### Running
<!-- Provide how to run the test for each SoC being tested -->
Custom app used to test:
- Tree view:
```
nuttxspace/
├── nuttx/
└── apps/
└── ulp_mailbox/
└── Makefile
└── Kconfig
└── ulp_mailbox.c // HP Application
└── ulp/
└── Makefile // LP Core Makefile
└── ulp_main.c // LP Core Application
```
- Contents in Makefile:
```
include $(APPDIR)/Make.defs
PROGNAME = $(CONFIG_EXAMPLES_ULP_MAILBOX_PROGNAME)
PRIORITY = $(CONFIG_EXAMPLES_ULP_MAILBOX_PRIORITY)
STACKSIZE = $(CONFIG_EXAMPLES_ULP_MAILBOX_STACKSIZE)
MODULE = $(CONFIG_EXAMPLES_ULP_MAILBOX)
MAINSRC = ulp_mailbox.c
include $(APPDIR)/Application.mk
include ulp/Makefile
```
- Contents in Kconfig:
```
config EXAMPLES_ULP_MAILBOX
bool "ULP Mailbox Example"
default n
```
- Contents in ulp_mailbox.c:
```
#include <nuttx/config.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <stdio.h>
#include <unistd.h>
#include <nuttx/fs/ioctl.h>
#include <sys/ioctl.h>
#include "ulp/ulp/ulp_main.h"
#include "ulp/ulp/ulp_code.h"
int main(int argc, char *argv[])
{
int fd;
int mailbox;
uint8_t data = 0;
int ret = OK;
int prev_data;
fd = open("/dev/ulp", O_WRONLY);
if (fd < 0)
{
printf("Failed to open ULP: %d\n", errno);
return -1;
}
write(fd, ulp_mailbox_bin, ulp_mailbox_bin_len);
mailbox = open("/dev/lp_mailbox", O_RDWR);
if (mailbox < 0)
{
printf("Failed to open LP Mailbox: %d\n", errno);
return -1;
}
/* Waiting for a while to let ULP start to run */
sleep(3);
for (int i = 0; i < 2; i++)
{
ret = write(mailbox, &data, 1);
if (ret != 1)
{
printf("Failed to send data\n");
return ERROR;
}
prev_data = data;
ret = read(mailbox, &data, 1);
if (ret != 1 || (prev_data + 1 != data))
{
printf("Failed to read data\n");
return ERROR;
}
else
{
printf("Read data: %d\n", data);
}
sleep(1);
}
printf("All done.\n");
return OK;
}
```
- Contents in ulp/Makefile:
```
ULP_APP_NAME = ulp_mailbox
ULP_APP_FOLDER = $(APPDIR)$(DELIM)ulp_mailbox$(DELIM)ulp
ULP_APP_C_SRCS = ulp_main.c
include
$(TOPDIR)$(DELIM)arch$(DELIM)$(CONFIG_ARCH)$(DELIM)src$(DELIM)common$(DELIM)espressif$(DELIM)ulp_makefile.mk
```
- Contents in ulp/ulp_main.c:
```
#include <stdint.h>
#include "nuttx/config.h"
#include <stdbool.h>
#include <stdint.h>
#include "ulp_lp_core_utils.h"
#include "ulp_lp_core_mailbox.h"
#define nop() __asm__ __volatile__ ("nop")
static lp_mailbox_t mailbox;
int main(void)
{
lp_core_mailbox_init(&mailbox, NULL);
lp_message_t message;
esp_err_t ret;
while (1)
{
ret = lp_core_mailbox_receive(mailbox, &message, UINT32_MAX);
if (ret == ESP_OK)
{
message = message + 1;
ret = lp_core_mailbox_send(mailbox, message, UINT32_MAX);
}
for (int i = 0; i < 100; i++)
{
nop();
}
}
return 0;
}
```
### Results
<!-- Provide tests' results and runtime logs -->
Output should look like this:
```
nsh> ls /dev
/dev:
...
lp_mailbox
...
nsh> custom_app
Read data: 1
Read data: 2
All done.
nsh>
```
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