[PATCH v2 7/7] hw/arm/exynos4210: Connect serial port DMA busy signals with pl330

[Guenter Roeck <linux@roeck-us.net>]

The Exynos4210 serial driver uses an interrupt line to signal if receive
data is available. Connect that interrupt with the DMA controller's
'peripheral busy' gpio pin to stop the DMA if there is no more receive
data available. Without this patch, receive DMA runs wild and fills the
entire receive DMA buffer with invalid data. 

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v2: Context changes; improved description
    This patch has an outstanding review comment, suggesting that
    uart and pl330 device states should be kept in Exynos4210State.
    I did not address this comment for a number of reasons.
    It looks like the problem is hypothetical, the problem may
    apply to all devices created in exynos4210_realize(), and I am
    not sure I understand what would need to be done to fix
    the problem for good (ie for all devices created in the same
    function which have the same problem). Overall, I think that
    handling this situation would be better left for a separate patch.

 hw/arm/exynos4210.c | 42 +++++++++++++++++++++++++++++-------------
 1 file changed, 29 insertions(+), 13 deletions(-)

diff --git a/hw/arm/exynos4210.c b/hw/arm/exynos4210.c
index 76c0e2a3e8..6b050bb5c9 100644
--- a/hw/arm/exynos4210.c
+++ b/hw/arm/exynos4210.c
@@ -166,8 +166,8 @@ static uint64_t exynos4210_calc_affinity(int cpu)
     return (0x9 << ARM_AFF1_SHIFT) | cpu;
 }
 
-static void pl330_create(uint32_t base, qemu_or_irq *orgate, qemu_irq irq,
-                         int nreq, int nevents, int width)
+static DeviceState *pl330_create(uint32_t base, qemu_or_irq *orgate,
+                                 qemu_irq irq, int nreq, int nevents, int width)
 {
     SysBusDevice *busdev;
     DeviceState *dev;
@@ -196,6 +196,7 @@ static void pl330_create(uint32_t base, qemu_or_irq *orgate, qemu_irq irq,
         sysbus_connect_irq(busdev, i, qdev_get_gpio_in(DEVICE(orgate), i));
     }
     qdev_connect_gpio_out(DEVICE(orgate), 0, irq);
+    return dev;
 }
 
 static void exynos4210_realize(DeviceState *socdev, Error **errp)
@@ -204,7 +205,7 @@ static void exynos4210_realize(DeviceState *socdev, Error **errp)
     MemoryRegion *system_mem = get_system_memory();
     qemu_irq gate_irq[EXYNOS4210_NCPUS][EXYNOS4210_IRQ_GATE_NINPUTS];
     SysBusDevice *busdev;
-    DeviceState *dev;
+    DeviceState *dev, *uart[4], *pl330[3];
     int i, n;
 
     for (n = 0; n < EXYNOS4210_NCPUS; n++) {
@@ -390,19 +391,19 @@ static void exynos4210_realize(DeviceState *socdev, Error **errp)
 
 
     /*** UARTs ***/
-    exynos4210_uart_create(EXYNOS4210_UART0_BASE_ADDR,
+    uart[0] = exynos4210_uart_create(EXYNOS4210_UART0_BASE_ADDR,
                            EXYNOS4210_UART0_FIFO_SIZE, 0, serial_hd(0),
                   s->irq_table[exynos4210_get_irq(EXYNOS4210_UART_INT_GRP, 0)]);
 
-    exynos4210_uart_create(EXYNOS4210_UART1_BASE_ADDR,
+    uart[1] = exynos4210_uart_create(EXYNOS4210_UART1_BASE_ADDR,
                            EXYNOS4210_UART1_FIFO_SIZE, 1, serial_hd(1),
                   s->irq_table[exynos4210_get_irq(EXYNOS4210_UART_INT_GRP, 1)]);
 
-    exynos4210_uart_create(EXYNOS4210_UART2_BASE_ADDR,
+    uart[2] = exynos4210_uart_create(EXYNOS4210_UART2_BASE_ADDR,
                            EXYNOS4210_UART2_FIFO_SIZE, 2, serial_hd(2),
                   s->irq_table[exynos4210_get_irq(EXYNOS4210_UART_INT_GRP, 2)]);
 
-    exynos4210_uart_create(EXYNOS4210_UART3_BASE_ADDR,
+    uart[3] = exynos4210_uart_create(EXYNOS4210_UART3_BASE_ADDR,
                            EXYNOS4210_UART3_FIFO_SIZE, 3, serial_hd(3),
                   s->irq_table[exynos4210_get_irq(EXYNOS4210_UART_INT_GRP, 3)]);
 
@@ -450,12 +451,27 @@ static void exynos4210_realize(DeviceState *socdev, Error **errp)
             s->irq_table[exynos4210_get_irq(28, 3)]);
 
     /*** DMA controllers ***/
-    pl330_create(EXYNOS4210_PL330_BASE0_ADDR, &s->pl330_irq_orgate[0],
-                 s->irq_table[exynos4210_get_irq(21, 0)], 32, 30, 32);
-    pl330_create(EXYNOS4210_PL330_BASE1_ADDR, &s->pl330_irq_orgate[1],
-                 s->irq_table[exynos4210_get_irq(21, 1)], 32, 30, 32);
-    pl330_create(EXYNOS4210_PL330_BASE2_ADDR, &s->pl330_irq_orgate[2],
-                 s->irq_table[exynos4210_get_irq(20, 1)], 1, 30, 64);
+    pl330[0] = pl330_create(EXYNOS4210_PL330_BASE0_ADDR,
+                            &s->pl330_irq_orgate[0],
+                            s->irq_table[exynos4210_get_irq(21, 0)],
+                            32, 30, 32);
+    pl330[1] = pl330_create(EXYNOS4210_PL330_BASE1_ADDR,
+                            &s->pl330_irq_orgate[1],
+                            s->irq_table[exynos4210_get_irq(21, 1)],
+                            32, 30, 32);
+    pl330[2] = pl330_create(EXYNOS4210_PL330_BASE2_ADDR,
+                            &s->pl330_irq_orgate[2],
+                            s->irq_table[exynos4210_get_irq(20, 1)],
+                            1, 30, 64);
+
+    sysbus_connect_irq(SYS_BUS_DEVICE(uart[0]), 1,
+                       qdev_get_gpio_in(pl330[0], 15));
+    sysbus_connect_irq(SYS_BUS_DEVICE(uart[1]), 1,
+                       qdev_get_gpio_in(pl330[1], 15));
+    sysbus_connect_irq(SYS_BUS_DEVICE(uart[2]), 1,
+                       qdev_get_gpio_in(pl330[0], 17));
+    sysbus_connect_irq(SYS_BUS_DEVICE(uart[3]), 1,
+                       qdev_get_gpio_in(pl330[1], 17));
 }
 
 static void exynos4210_init(Object *obj)
-- 
2.17.1