portable device access api based on unix file descriptors

bsp_linux/CMakeLists.txt

@@ -1 +1,3 @@
+add_subdirectory(hardware)
+
 target_sources(${TARGET_NAME} PRIVATE main.c)

bsp_linux/hardware/CMakeLists.txt

@@ -0,0 +1 @@
+target_sources(${TARGET_NAME} PRIVATE hardware.c)

bsp_linux/hardware/hardware.c

@@ -0,0 +1,28 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#include <hardware/interfaces.h>
+
+extern const char *device_root;
+
+int hw_device_open(const char *path, size_t path_len) {
+  int sock;
+  if ((sock = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) {
+    perror(NULL);
+    exit(-1);
+  }
+  struct sockaddr_un address;
+  address.sun_family = AF_UNIX;
+  snprintf(address.sun_path, sizeof(address.sun_path), "%s%.*s", device_root,
+           path_len, path);
+  if (connect(sock, (struct sockaddr *)&address, sizeof(address)) != 0) {
+    perror(NULL);
+    exit(-1);
+  }
+  return sock;
+}

bsp_linux/main.c

@@ -1,27 +1,52 @@
-#include <stdio.h>
+#include <errno.h>
+#include <getopt.h>
 #include <stdint.h>
+#include <stdio.h>
 #include <stdlib.h>
-
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
 #include <unistd.h>
 
+const char *device_root = "./";
+
 void mission(void);
 
-int get_descriptor_rw() {
-  return 1;
-}
+int get_descriptor_rw() { return 1; }
 
 void done() {
   printf("done.\n");
   exit(0);
 }
 
+int test_socket();
+
 // Don't ask me, it makes the linker happy and does not seem
 // to break anything ¯\_(ツ)_/¯
-void rust_eh_personality() {
-    puts("eh_personality");
+void rust_eh_personality() { puts("eh_personality"); }
+
+int main(int argc, char **argv) {
+  static struct option long_options[] = {
+      /*   NAME       ARGUMENT           FLAG  SHORTNAME */
+      {"device-root", required_argument, NULL, 'd'},
+      {"help", no_argument, NULL, 'h'},
+      {NULL, 0, NULL, 0}};
+  int c;
+  int option_index = 0;
+  while ((c = getopt_long(argc, argv, "hd:", long_options, &option_index)) !=
+         -1) {
+    switch (c) {
+    case 'd':
+      if (optarg != NULL) {
+        device_root = optarg;
+        break;
+      default:
+        fprintf(stderr, "Usage: %s -d device-root\n", argv[0]);
+        exit(EXIT_FAILURE);
+      }
+    }
   }
   
-int main(void) {
   mission();
   return 0;
 }

bsp_z7/CMakeLists.txt

@@ -1,5 +1,6 @@
 add_subdirectory(freeRTOS)
 add_subdirectory(ps7_cortexa9_0)
 add_subdirectory(newlib)
+add_subdirectory(hardware)
 
 target_sources(${TARGET_NAME} PRIVATE main.c)

bsp_z7/hardware/CMakeLists.txt

@@ -0,0 +1 @@
+target_sources(${TARGET_NAME} PRIVATE interfaces.c)

bsp_z7/hardware/interface_access.h

@@ -0,0 +1,5 @@
+#pragma once
+
+int hw_interface_write(int fd, const char *ptr, int len);
+
+int hw_interface_read(int fd, char *ptr, int len);

bsp_z7/hardware/interface_fds.h

@@ -0,0 +1,7 @@
+#pragma once
+
+enum InterfaceFileDescriptors {
+    UART_0 = 3,
+    UART_1,
+    INTERFACE_FDS_NEXT
+};

bsp_z7/hardware/interfaces.c

@@ -0,0 +1,70 @@
+#include <hardware/interfaces.h>
+#include <xparameters_ps.h>
+#include <xuartps.h>
+#include <stdint.h>
+
+#include "interface_access.h"
+#include "interface_fds.h"
+
+int compare_string_chars(const char *c_string, const char *chars,
+                         size_t chars_len) {
+  for(int i = 0; i < chars_len; i++) {
+    if (c_string[i] == 0) {
+      return 0;
+    }
+    if (c_string[i] != chars[i]) {;
+      return 0;
+    }
+  }
+  return 1;
+}
+
+int hw_device_open(const char *path, size_t path_len) {
+  if (compare_string_chars("uart0", path, path_len) == 1) {
+    return UART_0;
+  }
+  if (compare_string_chars("uart1", path, path_len) == 1) {
+    return UART_1;
+  }
+
+  return -1;
+}
+
+ssize_t hw_device_transfer(int fd, void *sendbuffer, void *receivebuffer,
+                           size_t buffer_len) {
+  return -1;
+}
+
+// we could implement interrupt based nonblocking sending using a queue
+// like we do receiving (where we need it for the small hw buffer)
+// but in the end, we do not want too many interrupts, so we do it blocking
+void send_uart(uint32_t BaseAddress, const char *data, int data_len) {
+  int todo;
+  for (todo = 0; todo < data_len; todo++) {
+    XUartPs_SendByte(BaseAddress, *data++);
+  }
+}
+
+int hw_interface_write(int fd, const char *ptr, int len) {
+  enum InterfaceFileDescriptors fd_enum = fd;
+  switch (fd) {
+  case UART_0:
+    send_uart(XPS_UART0_BASEADDR, ptr, len);
+    return len;
+  case UART_1:
+    send_uart(XPS_UART1_BASEADDR, ptr, len);
+    return len;
+  }
+  return -1;
+}
+
+int hw_interface_read(int fd, char *ptr, int len) {
+  enum InterfaceFileDescriptors fd_enum = fd;
+  switch (fd) {
+  case UART_0:
+    return 0;
+  case UART_1:
+    return 0;
+  }
+  return -1;
+}

bsp_z7/main.c

@@ -47,6 +47,10 @@ XScuGic xInterruptController;
 
 extern SemaphoreHandle_t malloc_mutex;
 
+int get_descriptor_rw() {
+  return 1;
+}
+
 /*-----------------------------------------------------------*/
 void mission(void);
 

bsp_z7/newlib/CMakeLists.txt

@@ -1 +1 @@
-target_sources(${TARGET_NAME} PRIVATE write.c)
+target_sources(${TARGET_NAME} PRIVATE close.c read.c write.c)

bsp_z7/newlib/read.c

@@ -0,0 +1,5 @@
+
+
+int _read(int file, char *ptr, int len) {
+  return 0;
+}

bsp_z7/newlib/write.c

@@ -1,11 +1,29 @@
 #include "xil_printf.h"
 #include "xparameters.h"
 
-int write(int file, char *ptr, int len) {
+#include "../hardware/interface_access.h"
+#include "../hardware/interface_fds.h"
+
+
+// newlib offers a (weak) write implementation which
+// is reentrant by calling _write_r which in turn
+// relies on _write which we implement here.
+// This way, we get a global, reentrant write implementation
+// NOTE: This might be architecture dependent, so check your
+// newlib implementation!
+int _write(int fd, const char *ptr, int len) {
   if (ptr == NULL) {
     return 0;
   }
-  // TODO file descriptors
+  
+  // 0 is stdin, do not write to it
+  if (fd < 1) {
+    return -1; // TODO error
+  }
+  // we only support a single debug UART, so
+  // stdout and stderr are the same and go to the xiling stdout UART
+  // TODO switch to a hw_interface_write() instead?
+  if (fd < 3) {
     int todo;
 
     for (todo = 0; todo < len; todo++) {
@@ -13,3 +31,11 @@ int write(int file, char *ptr, int len) {
     }
     return len;
   }
+
+  if (fd < INTERFACE_FDS_NEXT) {
+    return hw_interface_write(fd, ptr, len);
+  }
+
+  // we do not have dynamic fds, so fd is invalid
+  return -1;
+}

common/CMakeLists.txt

@@ -1,3 +1 @@
-target_sources(
-  ${TARGET_NAME} PRIVATE
-  printChar.c)
+target_include_directories(${TARGET_NAME} PRIVATE include)

common/include/hardware/interfaces.h

@@ -0,0 +1,37 @@
+#pragma once
+
+#include <stddef.h>
+#include <sys/types.h>
+
+/**
+ * Access to hardware interfaces local to the machine the code is running on.
+ * 
+ * The file descriptor returned by hw_decvice_open() is to be used by the standard
+ * read/write calls and to be closed by close().
+ * 
+ * For some specific hardware interfaces specific transactional calls are provided here
+ * to increase realtime performance.
+ * 
+ * So far the only example is an SPI interface, which performs synchronous transfers of
+ * n bytes in, n bytes out. If a write call is performed on such an interface, the number
+ * of bytes transfered equals the size of the hardware send buffer. For a read() call, the
+ * bytes contained in the hardware's receive buffer are returned.
+ */
+
+/**
+ * open a hardware device
+ * 
+ * if successful, returns a file descriptor to be used with read/write/transfer/close calls
+ * otherwise returns -1
+ */
+int hw_device_open(const char * path, size_t path_len);
+
+/**
+ * Perform a transfer of buffer_len bytes in and out.
+ * 
+ * sendbuffer and receivebuffer may be equal, where received bytes overwrite
+ * send bytes.
+ * 
+ * returns actual number of bytes transfered
+ */
+ssize_t hw_device_transfer(int fd, void* sendbuffer, void* receivebuffer, size_t buffer_len);

common/printChar.c

@@ -1,10 +0,0 @@
-#include <stdbool.h>
-#include <stdio.h>
-
-void printChar(const char* character, bool errStream) {
-  if (errStream) {
-    fprintf(stderr, "%c", *character);
-  } else {
-    printf("%c", *character);
-  }
-}

mission/mission.c

@@ -25,7 +25,14 @@ void init_task(void *) {
   vTaskDelete(NULL);
 }
 
+#include <unistd.h>
+#include <hardware/interfaces.h>
+
 void mission(void) {
+  int fd0 = hw_device_open("uart0", 5);
+  write(fd0, "uart0\n", 6);
+  int fd1 = hw_device_open("uart1", 5);
+  write(fd1, "uart1\n", 6);
 
   int taskParameters = 0;
 

mission_rust/Cargo.lock

@@ -2,40 +2,6 @@
 # It is not intended for manual editing.
 version = 3
 
-[[package]]
-name = "descriptor_procmac"
-version = "0.1.0"
-dependencies = [
- "quote",
-]
-
 [[package]]
 name = "mission_rust"
 version = "0.1.0"
-dependencies = [
- "descriptor_procmac",
-]
-
-[[package]]
-name = "proc-macro2"
-version = "1.0.86"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5e719e8df665df0d1c8fbfd238015744736151d4445ec0836b8e628aae103b77"
-dependencies = [
- "unicode-ident",
-]
-
-[[package]]
-name = "quote"
-version = "1.0.36"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0fa76aaf39101c457836aec0ce2316dbdc3ab723cdda1c6bd4e6ad4208acaca7"
-dependencies = [
- "proc-macro2",
-]
-
-[[package]]
-name = "unicode-ident"
-version = "1.0.12"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3354b9ac3fae1ff6755cb6db53683adb661634f67557942dea4facebec0fee4b"

mission_rust/Cargo.toml

@@ -11,6 +11,3 @@ panic = 'abort'
 
 [profile.release]
 panic = 'abort'
-
-[dependencies]
-descriptor_procmac = { path = "./descriptor_procmac" }

mission_rust/descriptor_procmac/Cargo.toml

@@ -1,10 +0,0 @@
-[package]
-name = "descriptor_procmac"
-version = "0.1.0"
-edition = "2021"
-
-[lib]
-proc-macro = true
-
-[dependencies]
-quote = "1.0"

mission_rust/descriptor_procmac/src/lib.rs

@@ -1,41 +0,0 @@
-#![crate_type = "proc-macro"]
-extern crate proc_macro;
-use proc_macro::TokenStream;
-
-#[proc_macro]
-pub fn Device_Descriptor(input: TokenStream) -> TokenStream {
-    let first_token = input.into_iter().next().unwrap(); // Do proper error handling!
-    let raw_string = first_token.to_string();
-    let raw_string_len = raw_string.len();
-    let identifier = &first_token.to_string()[1..raw_string_len-1];
-    println!("first: {}", identifier);
-    // let value = match first_token {
-    //     Literal { symbol, kind: Str, ..} => {println!("yes: {}", symbol); "12"},
-    //     _ => "13",
-    // };
-    // let string_value = match litrs::StringLit::try_from(first_token) {
-    //     Ok(string_lit) => string_lit,
-    //     Err(e) => return e.to_compile_error(),
-    // };
-    let getter_name = quote::format_ident!("get_descriptor_{}", identifier);
-    let struct_name = quote::format_ident!("Descriptor_{}", identifier);
-    let tokens = quote::quote!(
-        extern "C" {
-            pub fn #getter_name() -> core::ffi::c_int;
-            pub fn write(fd: core::ffi::c_int, buffer: *const core::ffi::c_void, count: usize) -> core::ffi::c_int;
-        }
-
-        struct #struct_name {}
-
-        impl Hardware_Write for #struct_name {
-            fn write(&mut self, buf: &[u8]) -> Result<core::ffi::c_int,()>{
-                unsafe {
-                    let fd = #getter_name( );
-                    let written = write(fd, buf.as_ptr() as *const core::ffi::c_void, buf.len());
-                    Ok(written)
-                }
-            }
-        }
-    );
-    tokens.into()
-}

mission_rust/src/lib.rs

@@ -11,14 +11,6 @@ use core::panic::PanicInfo;
 use fsrc::objectmanager::SystemObjectIF;
 use fsrc::*;
 
-use descriptor_procmac::Device_Descriptor;
-
-trait Hardware_Write {
-    fn write(&mut self, buf: &[u8]) -> Result<core::ffi::c_int,()>;
-}
-
-Device_Descriptor!("rw");
-
 extern "C" {
     fn done();
 }
@@ -78,9 +70,6 @@ extern "C" fn rust_alloc_failed(){
 #[no_mangle]
 extern "C" fn rust_main() {
     sifln!("Rust startup 🚀");
-    let mut rw = Descriptor_rw{};
-    let data: &[u8] = &[0x30,0x31,10];
-    _ = rw.write(data);
     mission();
     sifln!("Mission done");
 }