From 133b335bae86bcbc9ef02eaea8caeeb624320751 Mon Sep 17 00:00:00 2001
From: Chris Johns <chrisj@rtems.org>
Date: Tue, 12 Nov 2024 16:53:33 +1100
Subject: [PATCH] cpukit/libmisc/rtems-fdt: Add shell read and write handler
 support

The handlers allow indirect access to FDT resources registered with the
shell.

Closes #5152
---
 cpukit/include/rtems/rtems-fdt-shell.h     | 22 ++++++++++++
 cpukit/libmisc/rtems-fdt/rtems-fdt-shell.c | 42 ++++++++++++++++++++--
 2 files changed, 62 insertions(+), 2 deletions(-)

diff --git a/cpukit/include/rtems/rtems-fdt-shell.h b/cpukit/include/rtems/rtems-fdt-shell.h
index a4c87552b0..32fa738c4a 100644
--- a/cpukit/include/rtems/rtems-fdt-shell.h
+++ b/cpukit/include/rtems/rtems-fdt-shell.h
@@ -54,6 +54,28 @@ void rtems_fdt_add_shell_command (void);
  */
 rtems_fdt_handle* rtems_fdt_get_shell_handle (void);
 
+/**
+ * Write handler call to write from the address property.
+ */
+typedef void (*rtems_fdt_write_handler)(uintptr_t address, uint32_t value);
+
+/**
+ * Read handler call to read from the address property.
+ */
+typedef uint32_t (*rtems_fdt_read_handler)(uintptr_t address);
+
+/**
+ * Set the write handler returning the current handler.
+ */
+rtems_fdt_write_handler
+rtems_fdt_set_shell_write_handler (rtems_fdt_write_handler handler);
+
+/**
+ * Set the read handler returning the current handler.
+ */
+rtems_fdt_read_handler
+rtems_fdt_set_shell_read_handler (rtems_fdt_read_handler handler);
+
 #ifdef __cplusplus
 }
 #endif /* __cplusplus */
diff --git a/cpukit/libmisc/rtems-fdt/rtems-fdt-shell.c b/cpukit/libmisc/rtems-fdt/rtems-fdt-shell.c
index 0bf6c84208..1ee2e357b8 100644
--- a/cpukit/libmisc/rtems-fdt/rtems-fdt-shell.c
+++ b/cpukit/libmisc/rtems-fdt/rtems-fdt-shell.c
@@ -70,20 +70,42 @@ static long rtems_fdt_test_timeout = 5;
  */
 static rtems_fdt_handle cmd_fdt_handle;
 
+/**
+ * The write and read handlers.
+ */
+static void rtems_fdt_default_write (uintptr_t address, uint32_t value);
+static uint32_t rtems_fdt_default_read (uintptr_t address);
+
+static rtems_fdt_write_handler write_handler = rtems_fdt_default_write;;
+static rtems_fdt_read_handler read_handler = rtems_fdt_default_read;
+
 static void
-rtems_fdt_write (uintptr_t address, uint32_t value)
+rtems_fdt_default_write (uintptr_t address, uint32_t value)
 {
   volatile uint32_t* ap = (uint32_t*) address;
   *ap = value;
 }
 
 static uint32_t
-rtems_fdt_read (uintptr_t address)
+rtems_fdt_default_read (uintptr_t address)
 {
   volatile uint32_t* ap = (uint32_t*) address;
   return *ap;
 }
 
+
+static void
+rtems_fdt_write (uintptr_t address, uint32_t value)
+{
+  write_handler (address, value);
+}
+
+static uint32_t
+rtems_fdt_read (uintptr_t address)
+{
+  return read_handler (address);
+}
+
 static int
 rtems_fdt_wrong_number_of_args (void)
 {
@@ -785,3 +807,19 @@ rtems_fdt_get_shell_handle (void)
 {
   return &cmd_fdt_handle;
 }
+
+rtems_fdt_write_handler
+rtems_fdt_set_shell_write_handler (rtems_fdt_write_handler handler)
+{
+  rtems_fdt_write_handler tmp = write_handler;
+  write_handler = handler;
+  return tmp;
+}
+
+rtems_fdt_read_handler
+rtems_fdt_set_shell_read_handler (rtems_fdt_read_handler handler)
+{
+  rtems_fdt_read_handler tmp = read_handler;
+  read_handler = handler;
+  return tmp;
+}