ESP32: add support for mounting/umounting storage

Allow to mount and umount external storage such as SD/MMC or internal
flash using `esp:mount/4` and `esp:umount/1`.
Right now only `fat` filesystem is supported.

Their semantic and parameters resembles unix mount and umount syscalls.

Signed-off-by: Davide Bettio <davide@uninstall.it>

CHANGELOG.md

@@ -36,6 +36,8 @@ also non string parameters (e.g. `Enum.join([1, 2], ",")`
 - Support for `binary:copy/1,2`
 - Support for directory listing using POSIX APIs: (`atomvm:posix_opendir/1`,
 `atomvm:posix_readdir/1`, `atomvm:posix_closedir/1`).
+- Support for mounting/unmounting storage on ESP32 (such as SD or internal flash) using
+`esp:mount/4` and `esp:umount/1`
 
 ### Changed
 

libs/eavmlib/src/esp.erl

@@ -38,6 +38,8 @@
     sleep_enable_ulp_wakeup/0,
     deep_sleep/0,
     deep_sleep/1,
+    mount/4,
+    umount/1,
     nvs_fetch_binary/2,
     nvs_get_binary/1, nvs_get_binary/2, nvs_get_binary/3,
     nvs_set_binary/2, nvs_set_binary/3,
@@ -279,6 +281,34 @@ deep_sleep() ->
 deep_sleep(_SleepMS) ->
     erlang:nif_error(undefined).
 
+%%-----------------------------------------------------------------------------
+%% @param   Source the device that will be mounted
+%% @param   Target the path where the filesystem will be mounted
+%% @param   FS the filesystem, only fat is supported now
+%% @param   Opts
+%% @returns ok in case of success, otherwise an error
+%% @doc     Mount a filesystem
+%% @end
+%%-----------------------------------------------------------------------------
+-spec mount(
+    Source :: unicode:chardata(),
+    Target :: unicode:chardata(),
+    FS :: fat,
+    Opts :: proplists:proplist() | #{atom() => term()}
+) -> ok.
+mount(_Source, _Target, _FS, _Opts) ->
+    erlang:nif_error(undefined).
+
+%%-----------------------------------------------------------------------------
+%% @param   Target the path of the mounted filesystem that should be unmounted
+%% @returns ok
+%% @doc     Unmounts filesystem located at given path
+%% @end
+%%-----------------------------------------------------------------------------
+-spec umount(Target :: unicode:chardata()) -> ok.
+umount(_Target) ->
+    erlang:nif_error(undefined).
+
 %%-----------------------------------------------------------------------------
 %% @param   Namespace NVS namespace
 %% @param   Key NVS key

src/platforms/esp32/components/avm_builtins/CMakeLists.txt

@@ -27,6 +27,7 @@ set(AVM_BUILTIN_COMPONENT_SRCS
     "rtc_slow_nif.c"
     "socket_driver.c"
     "spi_driver.c"
+    "storage_nif.c"
     "uart_driver.c"
     "otp_crypto_platform.c"
     "otp_net_platform.c"
@@ -55,7 +56,7 @@ endif()
 idf_component_register(
     SRCS ${AVM_BUILTIN_COMPONENT_SRCS}
     INCLUDE_DIRS "include"
-    PRIV_REQUIRES "libatomvm" "avm_sys" "nvs_flash" "driver" "esp_event" "esp_wifi" ${ADDITIONAL_PRIV_REQUIRES}
+    PRIV_REQUIRES "libatomvm" "avm_sys" "nvs_flash" "driver" "esp_event" "esp_wifi" "fatfs" ${ADDITIONAL_PRIV_REQUIRES}
     ${OPTIONAL_WHOLE_ARCHIVE}
 )
 

src/platforms/esp32/components/avm_builtins/Kconfig

@@ -45,6 +45,10 @@ config AVM_RTC_SLOW_MAX_SIZE
     # 4KB is a reasonable default
     default 4096
 
+config AVM_ENABLE_STORAGE_NIFS
+    bool "Enable Storage NIFs"
+    default y
+
 config AVM_ENABLE_GPIO_PORT_DRIVER
     bool "Enable GPIO port driver"
     default y