1 files changed, 27 insertions, 9 deletions

diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
index 6278fe585c05..39b797bc14d6 100644
--- a/arch/arm/mach-omap2/serial.c
+++ b/arch/arm/mach-omap2/serial.c
@@ -33,6 +33,7 @@
 #include "pm.h"
 #include "prm-regbits-34xx.h"
 
+#define UART_OMAP_NO_EMPTY_FIFO_READ_IP_REV     0x52
 #define UART_OMAP_WER           0x17    /* Wake-up enable register */
 
 #define DEFAULT_TIMEOUT (5 * HZ)
@@ -572,6 +573,23 @@ static struct omap_uart_state omap_uart[] = {
 #endif
 };
 
+/*
+ * Override the default 8250 read handler: mem_serial_in()
+ * Empty RX fifo read causes an abort on omap3630 and omap4
+ * This function makes sure that an empty rx fifo is not read on these silicons
+ * (OMAP1/2/3430 are not affected)
+ */
+static unsigned int serial_in_override(struct uart_port *up, int offset)
+{
+        if (UART_RX == offset) {
+                unsigned int lsr;
+                lsr = serial_read_reg(omap_uart[up->line].p, UART_LSR);
+                if (!(lsr & UART_LSR_DR))
+                        return -EPERM;
+        }
+        return serial_read_reg(omap_uart[up->line].p, offset);
+}
+
 void __init omap_serial_early_init(void)
 {
         int i;
@@ -667,15 +685,15 @@ void __init omap_serial_init_port(int port)
                 DEV_CREATE_FILE(dev, &dev_attr_sleep_timeout);
         }
 
-        /* omap44xx: Never read empty UART fifo
-         * omap3xxx: Never read empty UART fifo on UARTs
-         * with IP rev >=0x52
-         */
-        if (cpu_is_omap44xx())
-                uart->p->serial_in = serial_in_override;
-        else if ((serial_read_reg(uart->p, UART_OMAP_MVER) & 0xFF)
-                        >= UART_OMAP_NO_EMPTY_FIFO_READ_IP_REV)
-                uart->p->serial_in = serial_in_override;
+                /* omap44xx: Never read empty UART fifo
+                 * omap3xxx: Never read empty UART fifo on UARTs
+                 * with IP rev >=0x52
+                 */
+                if (cpu_is_omap44xx())
+                        uart->p->serial_in = serial_in_override;
+                else if ((serial_read_reg(uart->p, UART_OMAP_MVER) & 0xFF)
+                                >= UART_OMAP_NO_EMPTY_FIFO_READ_IP_REV)
+                        uart->p->serial_in = serial_in_override;
 }
 
 /**