[ARM] S3C64XX: Demux UART interrupts

Add demux handling for the UART interrupts
generated by the VIC into their seperate IRQs
that the serial driver can register.
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

arch/arm/mach-s3c6400/include/mach/map.h

@@ -24,6 +24,14 @@
 #define S3C_PA_UART3		(S3C_PA_UART + 0xC00)
 #define S3C_UART_OFFSET		(0x400)
 
+/* See notes on UART VA mapping in debug-macro.S */
+#define S3C_VA_UARTx(x)	(S3C_VA_UART + (S3C_PA_UART & 0xfffff) + ((x) * S3C_UART_OFFSET))
+
+#define S3C_VA_UART0		S3C_VA_UARTx(0)
+#define S3C_VA_UART1		S3C_VA_UARTx(1)
+#define S3C_VA_UART2		S3C_VA_UARTx(2)
+#define S3C_VA_UART3		S3C_VA_UARTx(3)
+
 #define S3C64XX_PA_SYSCON	(0x7E00F000)
 #define S3C64XX_PA_TIMER	(0x7F006000)
 

arch/arm/plat-s3c64xx/irq.c

@@ -91,9 +91,144 @@ static struct irq_chip s3c_irq_timer = {
 	.ack		= s3c_irq_timer_ack,
 };
 
+struct uart_irq {
+	void __iomem	*regs;
+	unsigned int	 base_irq;
+	unsigned int	 parent_irq;
+};
+
+/* Note, we make use of the fact that the parent IRQs, IRQ_UART[0..3]
+ * are consecutive when looking up the interrupt in the demux routines.
+ */
+static struct uart_irq uart_irqs[] = {
+	[0] = {
+		.regs		= S3C_VA_UART0,
+		.base_irq	= IRQ_S3CUART_BASE0,
+		.parent_irq	= IRQ_UART0,
+	},
+	[1] = {
+		.regs		= S3C_VA_UART1,
+		.base_irq	= IRQ_S3CUART_BASE1,
+		.parent_irq	= IRQ_UART1,
+	},
+	[2] = {
+		.regs		= S3C_VA_UART2,
+		.base_irq	= IRQ_S3CUART_BASE2,
+		.parent_irq	= IRQ_UART2,
+	},
+	[3] = {
+		.regs		= S3C_VA_UART3,
+		.base_irq	= IRQ_S3CUART_BASE3,
+		.parent_irq	= IRQ_UART3,
+	},
+};
+
+static inline void __iomem *s3c_irq_uart_base(unsigned int irq)
+{
+	struct uart_irq *uirq = get_irq_chip_data(irq);
+	return uirq->regs;
+}
+
+static inline unsigned int s3c_irq_uart_bit(unsigned int irq)
+{
+	return irq & 3;
+}
+
+/* UART interrupt registers, not worth adding to seperate include header */
+#define S3C64XX_UINTP	0x30
+#define S3C64XX_UINTSP	0x34
+#define S3C64XX_UINTM	0x38
+
+static void s3c_irq_uart_mask(unsigned int irq)
+{
+	void __iomem *regs = s3c_irq_uart_base(irq);
+	unsigned int bit = s3c_irq_uart_bit(irq);
+	u32 reg;
+
+	reg = __raw_readl(regs + S3C64XX_UINTM);
+	reg |= (1 << bit);
+	__raw_writel(reg, regs + S3C64XX_UINTM);
+}
+
+static void s3c_irq_uart_maskack(unsigned int irq)
+{
+	void __iomem *regs = s3c_irq_uart_base(irq);
+	unsigned int bit = s3c_irq_uart_bit(irq);
+	u32 reg;
+
+	reg = __raw_readl(regs + S3C64XX_UINTM);
+	reg |= (1 << bit);
+	__raw_writel(reg, regs + S3C64XX_UINTM);
+	__raw_writel(1 << bit, regs + S3C64XX_UINTP);
+}
+
+static void s3c_irq_uart_unmask(unsigned int irq)
+{
+	void __iomem *regs = s3c_irq_uart_base(irq);
+	unsigned int bit = s3c_irq_uart_bit(irq);
+	u32 reg;
+
+	reg = __raw_readl(regs + S3C64XX_UINTM);
+	reg &= ~(1 << bit);
+	__raw_writel(reg, regs + S3C64XX_UINTM);
+}
+
+static void s3c_irq_uart_ack(unsigned int irq)
+{
+	void __iomem *regs = s3c_irq_uart_base(irq);
+	unsigned int bit = s3c_irq_uart_bit(irq);
+
+	__raw_writel(1 << bit, regs + S3C64XX_UINTP);
+}
+
+static void s3c_irq_demux_uart(unsigned int irq, struct irq_desc *desc)
+{
+	struct uart_irq *uirq = &uart_irqs[irq - IRQ_UART0];
+	u32 pend = __raw_readl(uirq->regs + S3C64XX_UINTP);
+	int base = uirq->base_irq;
+
+	if (pend & (1 << 0))
+		generic_handle_irq(base);
+	if (pend & (1 << 1))
+		generic_handle_irq(base + 1);
+	if (pend & (1 << 2))
+		generic_handle_irq(base + 2);
+	if (pend & (1 << 3))
+		generic_handle_irq(base + 3);
+}
+
+static struct irq_chip s3c_irq_uart = {
+	.name		= "s3c-uart",
+	.mask		= s3c_irq_uart_mask,
+	.unmask		= s3c_irq_uart_unmask,
+	.mask_ack	= s3c_irq_uart_maskack,
+	.ack		= s3c_irq_uart_ack,
+};
+
+static void __init s3c64xx_uart_irq(struct uart_irq *uirq)
+{
+	void *reg_base = uirq->regs;
+	unsigned int irq;
+	int offs;
+
+	/* mask all interrupts at the start. */
+	__raw_writel(0xf, reg_base + S3C64XX_UINTM);
+
+	for (offs = 0; offs < 3; offs++) {
+		irq = uirq->base_irq + offs;
+
+		set_irq_chip(irq, &s3c_irq_uart);
+		set_irq_chip_data(irq, uirq);
+		set_irq_handler(irq, handle_level_irq);
+		set_irq_flags(irq, IRQF_VALID);
+	}
+
+	set_irq_chained_handler(uirq->parent_irq, s3c_irq_demux_uart);
+}
+
 void __init s3c64xx_init_irq(u32 vic0_valid, u32 vic1_valid)
 {
-	int irq;
+	int uart, irq;
 
 	printk(KERN_INFO "%s: initialising interrupts\n", __func__);
 
@@ -114,6 +249,9 @@ void __init s3c64xx_init_irq(u32 vic0_valid, u32 vic1_valid)
 		set_irq_handler(irq, handle_level_irq);
 		set_irq_flags(irq, IRQF_VALID);
 	}
+
+	for (uart = 0; uart < ARRAY_SIZE(uart_irqs); uart++)
+		s3c64xx_uart_irq(&uart_irqs[uart]);
 }