intelfb: add vsync interrupt support

[04/05] intelfb: implement FBIO_WAITFORVSYNC ioctl

The (unofficial) FBIO_WAITFORVSYNC ioctl is implemented by sleeping on the appropriate waitqueue, as defined in my earlier patch. Currently, only display 0 (aka pipe A) is supported.
Signed-off-by: Eric Hustvedt <ehustvedt@cecropia.com>

drivers/video/intelfb/intelfb.h

@@ -304,6 +304,10 @@ struct intelfb_info {
 
 #define IS_I9XX(dinfo) (((dinfo)->chipset == INTEL_915G)||(dinfo->chipset == INTEL_915GM)||((dinfo)->chipset == INTEL_945G)||(dinfo->chipset==INTEL_945GM))
 
+#ifndef FBIO_WAITFORVSYNC
+#define FBIO_WAITFORVSYNC	_IOW('F', 0x20, __u32)
+#endif
+
 /*** function prototypes ***/
 
 extern int intelfb_var_to_depth(const struct fb_var_screeninfo *var);

drivers/video/intelfb/intelfbdrv.c

@@ -1473,6 +1473,19 @@ static int
 intelfb_ioctl(struct fb_info *info, unsigned int cmd, unsigned long arg)
 {
 	int retval = 0;
+	struct intelfb_info *dinfo = GET_DINFO(info);
+	u32 pipe = 0;
+
+	switch (cmd) {
+		case FBIO_WAITFORVSYNC:
+			if (get_user(pipe, (__u32 __user *)arg))
+				return -EFAULT;
+
+			retval = intelfbhw_wait_for_vsync(dinfo, pipe);
+			break;
+		default:
+			break;
+	}
 
 	return retval;
 }

drivers/video/intelfb/intelfbhw.c

@@ -2019,3 +2019,36 @@ intelfbhw_disable_irq(struct intelfb_info *dinfo) {
 		free_irq(dinfo->pdev->irq, dinfo);
 	}
 }
+
+int
+intelfbhw_wait_for_vsync(struct intelfb_info *dinfo, u32 pipe) {
+	struct intelfb_vsync *vsync;
+	unsigned int count;
+	int ret;
+
+	switch (pipe) {
+		case 0:
+			vsync = &dinfo->vsync;
+			break;
+		default:
+			return -ENODEV;
+	}
+
+	ret = intelfbhw_enable_irq(dinfo, 0);
+	if (ret) {
+		return ret;
+	}
+
+	count = vsync->count;
+	ret = wait_event_interruptible_timeout(vsync->wait, count != vsync->count, HZ/10);
+	if (ret < 0) {
+		return ret;
+	}
+	if (ret == 0) {
+		intelfbhw_enable_irq(dinfo, 1);
+		DBG_MSG("wait_for_vsync timed out!\n");
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}

drivers/video/intelfb/intelfbhw.h

@@ -563,5 +563,6 @@ extern void intelfbhw_cursor_load(struct intelfb_info *dinfo, int width,
 extern void intelfbhw_cursor_reset(struct intelfb_info *dinfo);
 extern int intelfbhw_enable_irq(struct intelfb_info *dinfo, int reenable);
 extern void intelfbhw_disable_irq(struct intelfb_info *dinfo);
+extern int intelfbhw_wait_for_vsync(struct intelfb_info *dinfo, u32 pipe);
 
 #endif /* _INTELFBHW_H */