intelfb: add vsync interrupt support

[03/05] intelfb: Implement basic interrupt handling

Functions have been added to enable and disable interrupts using the MMIO registers. Currently only pipe A vsync interrupts are enabled.
A generalized vsync accounting struct is defined, with the intent that it can encapsulate per-pipe vsync related info in the future. Currently a single instance is hard-coded.
The interrupt service routine currently only looks for vsync interrupts on pipe A, and increments a counter and wakes up anyone waiting on it.

This implementation is heavily influenced by similar implementations in the atyfb and matroxfb drivers.

Signed-off-by: Eric Hustvedt <ehustvedt@cecropia.com>

drivers/video/intelfb/intelfb.h

@@ -208,6 +208,11 @@ struct intelfb_heap_data {
 	u32 size;    // in bytes
 };
 
+struct intelfb_vsync {
+	wait_queue_head_t wait;
+	unsigned int count;
+};
+
 struct intelfb_info {
 	struct fb_info *info;
 	struct fb_ops  *fbops;
@@ -271,6 +276,12 @@ struct intelfb_info {
 	int fixed_mode;
 	int ring_active;
 	int flag;
+	unsigned long irq_flags;
+	int open;
+
+	/* vsync */
+	struct intelfb_vsync vsync;
+	spinlock_t int_lock;
 
 	/* hw cursor */
 	int cursor_on;

drivers/video/intelfb/intelfbdrv.c

@@ -137,6 +137,8 @@
 static void __devinit get_initial_mode(struct intelfb_info *dinfo);
 static void update_dinfo(struct intelfb_info *dinfo,
 			 struct fb_var_screeninfo *var);
+static int intelfb_open(struct fb_info *info, int user);
+static int intelfb_release(struct fb_info *info, int user);
 static int intelfb_check_var(struct fb_var_screeninfo *var,
 			     struct fb_info *info);
 static int intelfb_set_par(struct fb_info *info);
@@ -195,6 +197,8 @@ static int num_registered = 0;
 /* fb ops */
 static struct fb_ops intel_fb_ops = {
 	.owner =		THIS_MODULE,
+	.fb_open =              intelfb_open,
+	.fb_release =           intelfb_release,
 	.fb_check_var =         intelfb_check_var,
 	.fb_set_par =           intelfb_set_par,
 	.fb_setcolreg =		intelfb_setcolreg,
@@ -447,6 +451,8 @@ cleanup(struct intelfb_info *dinfo)
 	if (!dinfo)
 		return;
 
+	intelfbhw_disable_irq(dinfo);
+
 	fb_dealloc_cmap(&dinfo->info->cmap);
 	kfree(dinfo->info->pixmap.addr);
 
@@ -889,6 +895,11 @@ intelfb_pci_register(struct pci_dev *pdev, const struct pci_device_id *ent)
 	}
 
 	dinfo->registered = 1;
+	dinfo->open = 0;
+
+	init_waitqueue_head(&dinfo->vsync.wait);
+	spin_lock_init(&dinfo->int_lock);
+	dinfo->irq_flags = 0;
 
 	return 0;
 
@@ -1188,6 +1199,34 @@ update_dinfo(struct intelfb_info *dinfo, struct fb_var_screeninfo *var)
  *                       fbdev interface                       *
  ***************************************************************/
 
+static int
+intelfb_open(struct fb_info *info, int user)
+{
+	struct intelfb_info *dinfo = GET_DINFO(info);
+
+	if (user) {
+		dinfo->open++;
+	}
+
+	return 0;
+}
+
+static int
+intelfb_release(struct fb_info *info, int user)
+{
+	struct intelfb_info *dinfo = GET_DINFO(info);
+
+	if (user) {
+		dinfo->open--;
+		msleep(1);
+		if (!dinfo->open) {
+			intelfbhw_disable_irq(dinfo);
+		}
+	}
+
+	return 0;
+}
+
 static int
 intelfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
 {

drivers/video/intelfb/intelfbhw.c

@@ -34,6 +34,7 @@
 #include <linux/pci.h>
 #include <linux/vmalloc.h>
 #include <linux/pagemap.h>
+#include <linux/interrupt.h>
 
 #include <asm/io.h>
 
@@ -1943,3 +1944,78 @@ intelfbhw_cursor_reset(struct intelfb_info *dinfo) {
 		addr += 16;
 	}
 }
+
+static irqreturn_t
+intelfbhw_irq(int irq, void *dev_id, struct pt_regs *fp) {
+	int handled = 0;
+	u16 tmp;
+	struct intelfb_info *dinfo = (struct intelfb_info *)dev_id;
+
+	spin_lock(&dinfo->int_lock);
+
+	tmp = INREG16(IIR);
+	tmp &= VSYNC_PIPE_A_INTERRUPT;
+
+	if (tmp == 0) {
+		spin_unlock(&dinfo->int_lock);
+		return IRQ_RETVAL(handled);
+	}
+
+	OUTREG16(IIR, tmp);
+
+	if (tmp & VSYNC_PIPE_A_INTERRUPT) {
+		dinfo->vsync.count++;
+		wake_up_interruptible(&dinfo->vsync.wait);
+		handled = 1;
+	}
+
+	spin_unlock(&dinfo->int_lock);
+
+	return IRQ_RETVAL(handled);
+}
+
+int
+intelfbhw_enable_irq(struct intelfb_info *dinfo, int reenable) {
+
+	if (!test_and_set_bit(0, &dinfo->irq_flags)) {
+		if (request_irq(dinfo->pdev->irq, intelfbhw_irq, SA_SHIRQ, "intelfb", dinfo)) {
+			clear_bit(0, &dinfo->irq_flags);
+			return -EINVAL;
+		}
+
+		spin_lock_irq(&dinfo->int_lock);
+		OUTREG16(HWSTAM, 0xfffe);
+		OUTREG16(IMR, 0x0);
+		OUTREG16(IER, VSYNC_PIPE_A_INTERRUPT);
+		spin_unlock_irq(&dinfo->int_lock);
+	} else if (reenable) {
+		u16 ier;
+
+		spin_lock_irq(&dinfo->int_lock);
+		ier = INREG16(IER);
+		if ((ier & VSYNC_PIPE_A_INTERRUPT)) {
+			DBG_MSG("someone disabled the IRQ [%08X]\n", ier);
+			OUTREG(IER, VSYNC_PIPE_A_INTERRUPT);
+		}
+		spin_unlock_irq(&dinfo->int_lock);
+	}
+	return 0;
+}
+
+void
+intelfbhw_disable_irq(struct intelfb_info *dinfo) {
+	u16 tmp;
+
+	if (test_and_clear_bit(0, &dinfo->irq_flags)) {
+		spin_lock_irq(&dinfo->int_lock);
+		OUTREG16(HWSTAM, 0xffff);
+		OUTREG16(IMR, 0xffff);
+		OUTREG16(IER, 0x0);
+
+		tmp = INREG16(IIR);
+		OUTREG16(IIR, tmp);
+		spin_unlock_irq(&dinfo->int_lock);
+
+		free_irq(dinfo->pdev->irq, dinfo);
+	}
+}

drivers/video/intelfb/intelfbhw.h

@@ -561,5 +561,7 @@ extern void intelfbhw_cursor_setcolor(struct intelfb_info *dinfo, u32 bg,
 extern void intelfbhw_cursor_load(struct intelfb_info *dinfo, int width,
 				  int height, u8 *data);
 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);
 
 #endif /* _INTELFBHW_H */