[PATCH 4.5 69/87] serial: 8250_mid: recognize interrupt source in handler

Greg Kroah-Hartman
2016-05-30T21:00:38Z

From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

commit c42850f1ae7e70056f852e67bb9dddf927853b47 upstream.

There is a special register that shows interrupt status by source. In
particular case the source can be a combination of DMA Tx, DMA Rx, and UART.

Read the register and call the handlers only for sources that request an
interrupt.

Fixes: 6ede6dcd87aa ("serial: 8250_mid: add support for DMA engine handling from UART MMIO")
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/tty/serial/8250/8250_mid.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

--- a/drivers/tty/serial/8250/8250_mid.c
+++ b/drivers/tty/serial/8250/8250_mid.c
@@ -25,6 +25,7 @@
#define PCI_DEVICE_ID_INTEL_DNV_UART 0x19d8

/* Intel MID Specific registers */
+#define INTEL_MID_UART_DNV_FISR 0x08
#define INTEL_MID_UART_PS 0x30
#define INTEL_MID_UART_MUL 0x34
#define INTEL_MID_UART_DIV 0x38
@@ -90,16 +91,16 @@ static int tng_setup(struct mid8250 *mid
static int dnv_handle_irq(struct uart_port *p)
{
struct mid8250 *mid = p->private_data;
- int ret;
+ unsigned int fisr = serial_port_in(p, INTEL_MID_UART_DNV_FISR);
+ int ret = IRQ_NONE;

- ret = hsu_dma_irq(&mid->dma_chip, 0);
- ret |= hsu_dma_irq(&mid->dma_chip, 1);
-
- /* For now, letting the HW generate separate interrupt for the UART */
- if (ret)
- return ret;
-
- return serial8250_handle_irq(p, serial_port_in(p, UART_IIR));
+ if (fisr & BIT(2))
+ ret |= hsu_dma_irq(&mid->dma_chip, 1);
+ if (fisr & BIT(1))
+ ret |= hsu_dma_irq(&mid->dma_chip, 0);
+ if (fisr & BIT(0))
+ ret |= serial8250_handle_irq(p, serial_port_in(p, UART_IIR));
+ return ret;
}

#define DNV_DMA_CHAN_OFFSET 0x80