@@ -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
+ * (OMAP1/2/3 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;
@@ -650,5 +668,16 @@ void __init omap_serial_init(void)
device_init_wakeup(dev, true);
DEV_CREATE_FILE(dev, &dev_attr_sleep_timeout);
}
+
+#ifdef CONFIG_ARCH_OMAP4
+ /* Never read empty UART fifo on omap4 */
+ p->serial_in = serial_in_override;
+#else
+ /* OMAP2/3 */
+ /* Never read empty UART fifo on UARTs with IP rev >=0x52 */
+ 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;
+#endif
}
}