rt_device_write/read return data type as rt_ssize_t

rt_ssize_t can give negative error code, which follows the unix style correctly

1 files changed, 2 insertions, 2 deletions

diff --git a/libcpu/xilinx/microblaze/serial.c b/libcpu/xilinx/microblaze/serial.c
index 1902f11710..ea0070fb23 100755
--- a/libcpu/xilinx/microblaze/serial.c
+++ b/libcpu/xilinx/microblaze/serial.c
@@ -144,7 +144,7 @@ static rt_err_t rt_serial_close(rt_device_t dev)
     return RT_EOK;
 }
 
-static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     struct rt_mb_uart_lite *serial = (struct rt_mb_uart_lite*)dev;
@@ -212,7 +212,7 @@ static rt_size_t rt_serial_read (rt_device_t dev, rt_off_t pos, void* buffer, rt
     return 0;
 }
 
-static rt_size_t rt_serial_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
+static rt_ssize_t rt_serial_write (rt_device_t dev, rt_off_t pos, const void* buffer, rt_size_t size)
 {
     rt_uint8_t* ptr;
     struct rt_mb_uart_lite *serial = (struct rt_mb_uart_lite*)dev;