viafb: Add a simple interrupt management infrastructure

The viafb device shares a single interrupt control register among several
distinct subunits.  This adds a simple layer for management of that
register.

Cc: ScottFang@viatech.com.cn
Cc: JosephChan@via.com.tw
Cc: Harald Welte <laforge@gnumonks.org>
Acked-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

drivers/video/via/via-core.c

@@ -34,6 +34,65 @@ static struct via_port_cfg adap_configs[] = {
 static struct viafb_dev global_dev;
 
 
+/*
+ * Basic register access; spinlock required.
+ */
+static inline void viafb_mmio_write(int reg, u32 v)
+{
+	iowrite32(v, global_dev.engine_mmio + reg);
+}
+
+static inline int viafb_mmio_read(int reg)
+{
+	return ioread32(global_dev.engine_mmio + reg);
+}
+
+/* ---------------------------------------------------------------------- */
+/*
+ * Interrupt management.  We have a single IRQ line for a lot of
+ * different functions, so we need to share it.  The design here
+ * is that we don't want to reimplement the shared IRQ code here;
+ * we also want to avoid having contention for a single handler thread.
+ * So each subdev driver which needs interrupts just requests
+ * them directly from the kernel.  We just have what's needed for
+ * overall access to the interrupt control register.
+ */
+
+/*
+ * Which interrupts are enabled now?
+ */
+static u32 viafb_enabled_ints;
+
+static void viafb_int_init(void)
+{
+	viafb_enabled_ints = 0;
+
+	viafb_mmio_write(VDE_INTERRUPT, 0);
+}
+
+/*
+ * Allow subdevs to ask for specific interrupts to be enabled.  These
+ * functions must be called with reg_lock held
+ */
+void viafb_irq_enable(u32 mask)
+{
+	viafb_enabled_ints |= mask;
+	viafb_mmio_write(VDE_INTERRUPT, viafb_enabled_ints | VDE_I_ENABLE);
+}
+EXPORT_SYMBOL_GPL(viafb_irq_enable);
+
+void viafb_irq_disable(u32 mask)
+{
+	viafb_enabled_ints &= ~mask;
+	if (viafb_enabled_ints == 0)
+		viafb_mmio_write(VDE_INTERRUPT, 0);  /* Disable entirely */
+	else
+		viafb_mmio_write(VDE_INTERRUPT,
+				viafb_enabled_ints | VDE_I_ENABLE);
+}
+EXPORT_SYMBOL_GPL(viafb_irq_disable);
+
+
 /*
  * Figure out how big our framebuffer memory is.  Kind of ugly,
  * but evidently we can't trust the information found in the
@@ -275,8 +334,10 @@ static int __devinit via_pci_probe(struct pci_dev *pdev,
 	if (ret)
 		goto out_disable;
 	/*
-	 * Create our subdevices.  Continue even if some things fail.
+	 * Set up interrupts and create our subdevices.  Continue even if
+	 * some things fail.
 	 */
+	viafb_int_init();
 	via_setup_subdevs(&global_dev);
 	/*
 	 * Set up the framebuffer.
@@ -284,6 +345,7 @@ static int __devinit via_pci_probe(struct pci_dev *pdev,
 	ret = via_fb_pci_probe(&global_dev);
 	if (ret)
 		goto out_subdevs;
+
 	return 0;
 
 out_subdevs:

drivers/video/via/via-core.h

@@ -87,4 +87,48 @@ struct viafb_dev {
 
 };
 
+/*
+ * Interrupt management.
+ */
+
+void viafb_irq_enable(u32 mask);
+void viafb_irq_disable(u32 mask);
+
+/*
+ * The global interrupt control register and its bits.
+ */
+#define VDE_INTERRUPT	0x200	/* Video interrupt flags/masks */
+#define   VDE_I_DVISENSE  0x00000001  /* DVI sense int status */
+#define   VDE_I_VBLANK    0x00000002  /* Vertical blank status */
+#define   VDE_I_MCCFI	  0x00000004  /* MCE compl. frame int status */
+#define   VDE_I_VSYNC	  0x00000008  /* VGA VSYNC int status */
+#define   VDE_I_DMA0DDONE 0x00000010  /* DMA 0 descr done */
+#define   VDE_I_DMA0TDONE 0x00000020  /* DMA 0 transfer done */
+#define   VDE_I_DMA1DDONE 0x00000040  /* DMA 1 descr done */
+#define   VDE_I_DMA1TDONE 0x00000080  /* DMA 1 transfer done */
+#define   VDE_I_C1AV      0x00000100  /* Cap Eng 1 act vid end */
+#define   VDE_I_HQV0	  0x00000200  /* First HQV engine */
+#define   VDE_I_HQV1      0x00000400  /* Second HQV engine */
+#define   VDE_I_HQV1EN	  0x00000800  /* Second HQV engine enable */
+#define   VDE_I_C0AV      0x00001000  /* Cap Eng 0 act vid end */
+#define   VDE_I_C0VBI     0x00002000  /* Cap Eng 0 VBI end */
+#define   VDE_I_C1VBI     0x00004000  /* Cap Eng 1 VBI end */
+#define   VDE_I_VSYNC2    0x00008000  /* Sec. Disp. VSYNC */
+#define   VDE_I_DVISNSEN  0x00010000  /* DVI sense enable */
+#define   VDE_I_VSYNC2EN  0x00020000  /* Sec Disp VSYNC enable */
+#define   VDE_I_MCCFIEN	  0x00040000  /* MC comp frame int mask enable */
+#define   VDE_I_VSYNCEN   0x00080000  /* VSYNC enable */
+#define   VDE_I_DMA0DDEN  0x00100000  /* DMA 0 descr done enable */
+#define   VDE_I_DMA0TDEN  0x00200000  /* DMA 0 trans done enable */
+#define   VDE_I_DMA1DDEN  0x00400000  /* DMA 1 descr done enable */
+#define   VDE_I_DMA1TDEN  0x00800000  /* DMA 1 trans done enable */
+#define   VDE_I_C1AVEN    0x01000000  /* cap 1 act vid end enable */
+#define   VDE_I_HQV0EN	  0x02000000  /* First hqv engine enable */
+#define   VDE_I_C1VBIEN	  0x04000000  /* Cap 1 VBI end enable */
+#define   VDE_I_LVDSSI    0x08000000  /* LVDS sense interrupt */
+#define   VDE_I_C0AVEN    0x10000000  /* Cap 0 act vid end enable */
+#define   VDE_I_C0VBIEN   0x20000000  /* Cap 0 VBI end enable */
+#define   VDE_I_LVDSSIEN  0x40000000  /* LVDS Sense enable */
+#define   VDE_I_ENABLE	  0x80000000  /* Global interrupt enable */
+
 #endif /* __VIA_CORE_H__ */