V4L/DVB (7006): cx23885: Track the board clock frequency and allow overrides

The cx23885/6/8 all have different clock rates, this patch allows
the core to compensate, and developers to allow vendor specific
overrides. This patches will be used by future analog video
and encoder patches.
Signed-off-by: Steven Toth <stoth@hauppauge.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/cx23885/cx23885-cards.c

@@ -32,6 +32,8 @@
 struct cx23885_board cx23885_boards[] = {
 	[CX23885_BOARD_UNKNOWN] = {
 		.name		= "UNKNOWN/GENERIC",
+		/* Ensure safe default for unknown boards */
+		.clk_freq       = 0,
 		.input          = {{
 			.type   = CX23885_VMUX_COMPOSITE1,
 			.vmux   = 0,

drivers/media/video/cx23885/cx23885-core.c

@@ -759,10 +759,14 @@ static int cx23885_dev_setup(struct cx23885_dev *dev)
 	if(dev->pci->device == 0x8880) {
 		dev->bridge = CX23885_BRIDGE_887;
 		dev->sram_channels = cx23887_sram_channels;
+		/* Apply a sensible clock frequency for the PCIe bridge */
+		dev->clk_freq = 25000000;
 	} else
 	if(dev->pci->device == 0x8852) {
 		dev->bridge = CX23885_BRIDGE_885;
 		dev->sram_channels = cx23885_sram_channels;
+		/* Apply a sensible clock frequency for the PCIe bridge */
+		dev->clk_freq = 28000000;
 	} else
 		BUG();
 
@@ -782,6 +786,10 @@ static int cx23885_dev_setup(struct cx23885_dev *dev)
 		cx23885_card_list(dev);
 	}
 
+	/* If the user specific a clk freq override, apply it */
+	if (cx23885_boards[dev->board].clk_freq > 0)
+		dev->clk_freq = cx23885_boards[dev->board].clk_freq;
+
 	dev->pci_bus  = dev->pci->bus->number;
 	dev->pci_slot = PCI_SLOT(dev->pci->devfn);
 	dev->pci_irqmask = 0x001f00;

drivers/media/video/cx23885/cx23885.h

@@ -100,6 +100,17 @@ typedef enum {
 struct cx23885_board {
 	char                    *name;
 	port_t			portb, portc;
+
+	/* Vendors can and do run the PCIe bridge at different
+	 * clock rates, driven physically by crystals on the PCBs.
+	 * The core has to accomodate this. This allows the user
+	 * to add new boards with new frequencys. The value is
+	 * expressed in Hz.
+	 *
+	 * The core framework will default this value based on
+	 * current designs, but it can vary.
+	 */
+	u32			clk_freq;
 	struct cx23885_input    input[MAX_CX23885_INPUT];
 };
 
@@ -193,6 +204,10 @@ struct cx23885_dev {
 	int                        pci_irqmask;
 	int                        hwrevision;
 
+	/* This valud is board specific and is used to configure the
+	 * AV core so we see nice clean and stable video and audio. */
+	u32                        clk_freq;
+
 	/* I2C adapters: Master 1 & 2 (External) & Master 3 (Internal only) */
 	struct cx23885_i2c         i2c_bus[3];