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>

4 files changed, 128 insertions, 0 deletions

diff --git a/drivers/video/intelfb/intelfb.h b/drivers/video/intelfb/intelfb.h
index cb016fe4d48..dab1f2d764d 100644
--- a/drivers/video/intelfb/intelfb.h
+++ b/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;
diff --git a/drivers/video/intelfb/intelfbdrv.c b/drivers/video/intelfb/intelfbdrv.c
index 0a0a8b199ec..068c56d4e65 100644
--- a/drivers/video/intelfb/intelfbdrv.c
+++ b/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;
 
@@ -1189,6 +1200,34 @@ update_dinfo(struct intelfb_info *dinfo, struct fb_var_screeninfo *var)
  ***************************************************************/
 
 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)
 {
         int change_var = 0;
diff --git a/drivers/video/intelfb/intelfbhw.c b/drivers/video/intelfb/intelfbhw.c
index 05aded669cd..1a698a7230e 100644
--- a/drivers/video/intelfb/intelfbhw.c
+++ b/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);
+        }
+}
diff --git a/drivers/video/intelfb/intelfbhw.h b/drivers/video/intelfb/intelfbhw.h
index 8d2e36972fc..aa0c139a230 100644
--- a/drivers/video/intelfb/intelfbhw.h
+++ b/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 */