1 files changed, 73 insertions, 15 deletions

diff --git a/arch/arm/mach-omap2/serial.c b/arch/arm/mach-omap2/serial.c
index 2e17b57f5b23..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;
@@ -631,24 +649,64 @@ void __init omap_serial_early_init(void)
         }
 }
 
-void __init omap_serial_init(void)
+/**
+ * omap_serial_init_port() - initialize single serial port
+ * @port: serial port number (0-3)
+ *
+ * This function initialies serial driver for given @port only.
+ * Platforms can call this function instead of omap_serial_init()
+ * if they don't plan to use all available UARTs as serial ports.
+ *
+ * Don't mix calls to omap_serial_init_port() and omap_serial_init(),
+ * use only one of the two.
+ */
+void __init omap_serial_init_port(int port)
 {
-        int i;
+        struct omap_uart_state *uart;
+        struct platform_device *pdev;
+        struct device *dev;
 
-        for (i = 0; i < ARRAY_SIZE(omap_uart); i++) {
-                struct omap_uart_state *uart = &omap_uart[i];
-                struct platform_device *pdev = &uart->pdev;
-                struct device *dev = &pdev->dev;
+        BUG_ON(port < 0);
+        BUG_ON(port >= ARRAY_SIZE(omap_uart));
 
-                omap_uart_reset(uart);
-                omap_uart_idle_init(uart);
+        uart = &omap_uart[port];
+        pdev = &uart->pdev;
+        dev = &pdev->dev;
 
-                if (WARN_ON(platform_device_register(pdev)))
-                        continue;
-                if ((cpu_is_omap34xx() && uart->padconf) ||
-                    (uart->wk_en && uart->wk_mask)) {
-                        device_init_wakeup(dev, true);
-                        DEV_CREATE_FILE(dev, &dev_attr_sleep_timeout);
-                }
+        omap_uart_reset(uart);
+        omap_uart_idle_init(uart);
+
+        if (WARN_ON(platform_device_register(pdev)))
+                return;
+
+        if ((cpu_is_omap34xx() && uart->padconf) ||
+            (uart->wk_en && uart->wk_mask)) {
+                device_init_wakeup(dev, true);
+                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;
+}
+
+/**
+ * omap_serial_init() - intialize all supported serial ports
+ *
+ * Initializes all available UARTs as serial ports. Platforms
+ * can call this function when they want to have default behaviour
+ * for serial ports (e.g initialize them all as serial ports).
+ */
+void __init omap_serial_init(void)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(omap_uart); i++)
+                omap_serial_init_port(i);
 }