pcmcia: honor saved flags in yenta_socket's I365_CSCINT register

Instead of overwriting the I365_CSCINT register, save the old value and
merely change the bits we care about.

Part 1 of a series to allow the ISA irq to be used for Cardbus devices
if the socket's PCI irq is unusable.

[[e-mail]: split up the original patch, commit message]

Signed-off-by: Jens Kuenzer <[e-mail]>
Signed-off-by: Dominik Brodowski <[e-mail]>

drivers/pcmcia/i82365.h

···
 #define I365_CSC_DETECT	0x08
 #define I365_CSC_ANY	0x0F
 #define I365_CSC_GPI	0x10
+#define I365_CSC_IRQ_MASK	0xF0
 
 /* Flags for I365_ADDRWIN */
 #define I365_ENA_IO(map)	(0x40 << (map))

drivers/pcmcia/yenta_socket.c

···
 			exca_writeb(socket, I365_POWER, reg);
 
 		/* CSC interrupt: no ISA irq for CSC */
-		reg = I365_CSC_DETECT;
+		reg = exca_readb(socket, I365_CSCINT);
+		reg &= I365_CSC_IRQ_MASK;
+		reg |= I365_CSC_DETECT;
 		if (state->flags & SS_IOCARD) {
 			if (state->csc_mask & SS_STSCHG)
 				reg |= I365_CSC_STSCHG;
···
 	int i;
 	unsigned long val;
 	u32 mask;
+	u8 reg;
 
 	/*
 	 * Probe for usable interrupts using the force
···
 	 */
 	cb_writel(socket, CB_SOCKET_EVENT, -1);
 	cb_writel(socket, CB_SOCKET_MASK, CB_CSTSMASK);
+	reg = exca_readb(socket, I365_CSCINT);
 	exca_writeb(socket, I365_CSCINT, 0);
 	val = probe_irq_on() & isa_irq_mask;
 	for (i = 1; i < 16; i++) {
···
 		cb_writel(socket, CB_SOCKET_EVENT, -1);
 	}
 	cb_writel(socket, CB_SOCKET_MASK, 0);
-	exca_writeb(socket, I365_CSCINT, 0);
+	exca_writeb(socket, I365_CSCINT, reg);
 
 	mask = probe_irq_mask(val) & 0xffff;
 
···
 /* probes the PCI interrupt, use only on override functions */
 static int yenta_probe_cb_irq(struct yenta_socket *socket)
 {
+	u8 reg;
+
 	if (!socket->cb_irq)
 		return -1;
 
···
 	}
 
 	/* generate interrupt, wait */
-	exca_writeb(socket, I365_CSCINT, I365_CSC_STSCHG);
+	reg = exca_readb(socket, I365_CSCINT);
+	exca_writeb(socket, I365_CSCINT, reg | I365_CSC_STSCHG);
 	cb_writel(socket, CB_SOCKET_EVENT, -1);
 	cb_writel(socket, CB_SOCKET_MASK, CB_CSTSMASK);
 	cb_writel(socket, CB_SOCKET_FORCE, CB_FCARDSTS);
···
 
 	/* disable interrupts */
 	cb_writel(socket, CB_SOCKET_MASK, 0);
-	exca_writeb(socket, I365_CSCINT, 0);
+	exca_writeb(socket, I365_CSCINT, reg);
 	cb_writel(socket, CB_SOCKET_EVENT, -1);
 	exca_readb(socket, I365_CSC);