[rtems commit] pc386/console/fb*.c: Use atomics to avoid dependency on pthreads
Joel Sherril
joel at rtems.org
Thu Jun 11 15:11:20 UTC 2015
Module: rtems
Branch: master
Commit: becbedac784793f7701cbdbe2c6b3360e86d0778
Changeset: http://git.rtems.org/rtems/commit/?id=becbedac784793f7701cbdbe2c6b3360e86d0778
Author: Joel Sherrill <joel.sherrill at oarcorp.com>
Date: Tue Jun 9 13:48:22 2015 -0700
pc386/console/fb*.c: Use atomics to avoid dependency on pthreads
closes #2364.
---
c/src/lib/libbsp/i386/pc386/console/fb_cirrus.c | 29 ++++++++++-----------
c/src/lib/libbsp/i386/pc386/console/fb_vesa_rm.c | 32 ++++++++++++------------
c/src/lib/libbsp/i386/pc386/console/fb_vga.c | 28 ++++++++++-----------
3 files changed, 45 insertions(+), 44 deletions(-)
diff --git a/c/src/lib/libbsp/i386/pc386/console/fb_cirrus.c b/c/src/lib/libbsp/i386/pc386/console/fb_cirrus.c
index 1b311a1..15d36a3 100644
--- a/c/src/lib/libbsp/i386/pc386/console/fb_cirrus.c
+++ b/c/src/lib/libbsp/i386/pc386/console/fb_cirrus.c
@@ -27,9 +27,10 @@
#include <rtems/fb.h>
#include <rtems/framebuffer.h>
+#include <rtems/score/atomic.h>
-/* mutex to limit driver to protect against multiple opens */
-static pthread_mutex_t cirrus_mutex = PTHREAD_MUTEX_INITIALIZER;
+/* flag to limit driver to protect against multiple opens */
+static Atomic_Flag driver_mutex;
/* screen information for the VGA driver
* standard structures
@@ -332,6 +333,8 @@ frame_buffer_initialize(
rtems_fatal_error_occurred( status );
}
+ _Atomic_Flag_clear(&driver_mutex, ATOMIC_ORDER_RELEASE);
+
return RTEMS_SUCCESSFUL;
}
}
@@ -591,8 +594,8 @@ frame_buffer_open(
int r;
uint32_t smem_start, regs_start;
- if (pthread_mutex_trylock(&cirrus_mutex)!= 0){
- printk( "FB_CIRRUS could not lock cirrus_mutex\n" );
+ if (_Atomic_Flag_test_and_set(&driver_mutex, ATOMIC_ORDER_ACQUIRE) != 0 ) {
+ printk( "FB_CIRRUS could not lock driver_mutex\n" );
return RTEMS_UNSATISFIED;
}
@@ -662,19 +665,17 @@ frame_buffer_close(
void *arg
)
{
- if (pthread_mutex_unlock(&cirrus_mutex) == 0){
- /* restore previous state. for VGA this means return to text mode.
- * leave out if graphics hardware has been initialized in
- * frame_buffer_initialize() */
+ _Atomic_Flag_clear(&driver_mutex, ATOMIC_ORDER_RELEASE);
- /* VGA text mode */
- fb_cirrus_write_gdc_reg(&cirrus_board_info, 0x06, 0x00);
+ /* restore previous state. for VGA this means return to text mode.
+ * leave out if graphics hardware has been initialized in
+ * frame_buffer_initialize() */
- printk( "FB_CIRRUS: close called.\n" );
- return RTEMS_SUCCESSFUL;
- }
+ /* VGA text mode */
+ fb_cirrus_write_gdc_reg(&cirrus_board_info, 0x06, 0x00);
- return RTEMS_UNSATISFIED;
+ printk( "FB_CIRRUS: close called.\n" );
+ return RTEMS_SUCCESSFUL;
}
/*
diff --git a/c/src/lib/libbsp/i386/pc386/console/fb_vesa_rm.c b/c/src/lib/libbsp/i386/pc386/console/fb_vesa_rm.c
index 33dfc35..b758564 100644
--- a/c/src/lib/libbsp/i386/pc386/console/fb_vesa_rm.c
+++ b/c/src/lib/libbsp/i386/pc386/console/fb_vesa_rm.c
@@ -55,6 +55,8 @@
#include <rtems/fb.h>
#include <rtems/framebuffer.h>
+#include <rtems/score/atomic.h>
+
#include <stdlib.h>
#define FB_VESA_NAME "FB_VESA_RM"
@@ -84,8 +86,8 @@ const char * const rtems_fb_default_mode;
*/
void vesa_realmode_bootup_init(void);
-/* mutex for protection against multiple opens, when called frame_buffer_open */
-static pthread_mutex_t vesa_mutex = PTHREAD_MUTEX_INITIALIZER;
+/* flag to limit driver to protect against multiple opens */
+static Atomic_Flag driver_mutex;
/* screen information for the VGA driver
* standard structures - from RTEMS fb interface
@@ -840,9 +842,9 @@ frame_buffer_initialize(
printk(FB_VESA_NAME " frame buffer -- driver initializing..\n" );
-/*
- * Register the device.
- */
+ /*
+ * Register the device.
+ */
status = rtems_io_register_name(FRAMEBUFFER_DEVICE_0_NAME, major, 0);
if (status != RTEMS_SUCCESSFUL)
{
@@ -851,6 +853,8 @@ frame_buffer_initialize(
rtems_fatal_error_occurred( status );
}
+ _Atomic_Flag_clear(&driver_mutex, ATOMIC_ORDER_RELEASE);
+
return RTEMS_SUCCESSFUL;
}
@@ -866,7 +870,7 @@ frame_buffer_open(
{
printk( FB_VESA_NAME " open device\n" );
- if (pthread_mutex_trylock(&vesa_mutex) != 0)
+ if (_Atomic_Flag_test_and_set(&driver_mutex, ATOMIC_ORDER_ACQUIRE) != 0 )
{
printk( FB_VESA_NAME " could not lock vesa_mutex\n" );
@@ -888,17 +892,13 @@ frame_buffer_close(
)
{
printk( FB_VESA_NAME " close device\n" );
- if (pthread_mutex_unlock(&vesa_mutex) == 0)
- {
- /* restore previous state. for VGA this means return to text mode.
- * leave out if graphics hardware has been initialized in
- * frame_buffer_initialize() */
-
- printk(FB_VESA_NAME ": close called.\n" );
- return RTEMS_SUCCESSFUL;
- }
+ _Atomic_Flag_clear(&driver_mutex, ATOMIC_ORDER_RELEASE);
+ /* restore previous state. for VGA this means return to text mode.
+ * leave out if graphics hardware has been initialized in
+ * frame_buffer_initialize() */
- return RTEMS_UNSATISFIED;
+ printk(FB_VESA_NAME ": close called.\n" );
+ return RTEMS_SUCCESSFUL;
}
/*
diff --git a/c/src/lib/libbsp/i386/pc386/console/fb_vga.c b/c/src/lib/libbsp/i386/pc386/console/fb_vga.c
index 444f44d..75ad56e 100644
--- a/c/src/lib/libbsp/i386/pc386/console/fb_vga.c
+++ b/c/src/lib/libbsp/i386/pc386/console/fb_vga.c
@@ -20,12 +20,14 @@
#include <rtems/fb.h>
#include <rtems/framebuffer.h>
+#include <rtems/score/atomic.h>
+
/* these routines are defined in vgainit.c.*/
extern void ega_hwinit( void );
extern void ega_hwterm( void );
-/* mutex attribure */
-pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
+/* flag to limit driver to protect against multiple opens */
+static Atomic_Flag driver_mutex;
/* screen information for the VGA driver */
static struct fb_var_screeninfo fb_var =
@@ -87,6 +89,8 @@ rtems_device_driver frame_buffer_initialize(
rtems_fatal_error_occurred( status );
}
+ _Atomic_Flag_clear(&driver_mutex, ATOMIC_ORDER_RELEASE);
+
return RTEMS_SUCCESSFUL;
}
@@ -99,7 +103,7 @@ rtems_device_driver frame_buffer_open(
void *arg
)
{
- if (pthread_mutex_trylock(&mutex)== 0){
+ if (_Atomic_Flag_test_and_set(&driver_mutex, ATOMIC_ORDER_ACQUIRE) != 0 ) {
/* restore previous state. for VGA this means return to text mode.
* leave out if graphics hardware has been initialized in
* frame_buffer_initialize()
@@ -121,17 +125,13 @@ rtems_device_driver frame_buffer_close(
void *arg
)
{
- if (pthread_mutex_unlock(&mutex) == 0){
- /* restore previous state. for VGA this means return to text mode.
- * leave out if graphics hardware has been initialized in
- * frame_buffer_initialize() */
- ega_hwterm();
- printk( "FBVGA close called.\n" );
- return RTEMS_SUCCESSFUL;
- }
-
- return RTEMS_UNSATISFIED;
-}
+ _Atomic_Flag_clear(&driver_mutex, ATOMIC_ORDER_RELEASE);
+ /* restore previous state. for VGA this means return to text mode.
+ * leave out if graphics hardware has been initialized in
+ * frame_buffer_initialize() */
+ ega_hwterm();
+ printk( "FBVGA close called.\n" );
+ return RTEMS_SUCCESSFUL;
/*
* fbvga device driver READ entry point.
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