[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>

1 files changed, 139 insertions, 1 deletions

diff --git a/arch/arm/plat-s3c64xx/irq.c b/arch/arm/plat-s3c64xx/irq.c
index 1e6fa5c828c..99df9dbefa6 100644
--- a/arch/arm/plat-s3c64xx/irq.c
+++ b/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]);
 }