tty: moxa: rework the locking a bit

Introduce a lock for moxafunc() to protect the cases where were get collisions
between two function requests at the same time.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/drivers/char/moxa.c b/drivers/char/moxa.c
index d8bcbed6d28ddf213ed2d8d87cb4040083a10f01..474d936d3b31935f44fca52262e93a1e3db3f32f 100644 (file)
--- a/drivers/char/moxa.c
+++ b/drivers/char/moxa.c
@@ -248,9 +248,25 @@ static void moxa_wait_finish(void __iomem *ofsAddr)
 
 static void moxafunc(void __iomem *ofsAddr, u16 cmd, u16 arg)
 {
+        unsigned long flags;
+        spin_lock_irqsave(&moxafunc_lock, flags);
        writew(arg, ofsAddr + FuncArg);
        writew(cmd, ofsAddr + FuncCode);
        moxa_wait_finish(ofsAddr);
+       spin_unlock_irqrestore(&moxafunc_lock, flags);
+}
+
+static int moxafuncret(void __iomem *ofsAddr, u16 cmd, u16 arg)
+{
+        unsigned long flags;
+        u16 ret;
+        spin_lock_irqsave(&moxafunc_lock, flags);
+       writew(arg, ofsAddr + FuncArg);
+       writew(cmd, ofsAddr + FuncCode);
+       moxa_wait_finish(ofsAddr);
+       ret = readw(ofsAddr + FuncArg);
+       spin_unlock_irqrestore(&moxafunc_lock, flags);
+       return ret;
 }
 
 static void moxa_low_water_check(void __iomem *ofsAddr)
@@ -417,6 +433,7 @@ static const struct tty_port_operations moxa_port_ops = {
 static struct tty_driver *moxaDriver;
 static DEFINE_TIMER(moxaTimer, moxa_poll, 0, 0);
 static DEFINE_SPINLOCK(moxa_lock);
+static DEFINE_SPINLOCK(moxafunc_lock);
 
 /*
  * HW init
@@ -1823,10 +1840,12 @@ static int MoxaPortSetTermio(struct moxa_port *port, struct ktermios *termio,
        baud = MoxaPortSetBaud(port, baud);
 
        if (termio->c_iflag & (IXON | IXOFF | IXANY)) {
+               spin_lock_irq(&moxafunc_lock);
                writeb(termio->c_cc[VSTART], ofsAddr + FuncArg);
                writeb(termio->c_cc[VSTOP], ofsAddr + FuncArg1);
                writeb(FC_SetXonXoff, ofsAddr + FuncCode);
                moxa_wait_finish(ofsAddr);
+               spin_unlock_irqrestore(&moxafunc_lock);
 
        }
        return baud;
@@ -1879,12 +1898,10 @@ static int MoxaPortLineStatus(struct moxa_port *port)
        int val;
 
        ofsAddr = port->tableAddr;
-       if (MOXA_IS_320(port->board)) {
-               moxafunc(ofsAddr, FC_LineStatus, 0);
-               val = readw(ofsAddr + FuncArg);
-       } else {
+       if (MOXA_IS_320(port->board))
+               val = moxafuncret(ofsAddr, FC_LineStatus, 0);
+       else
                val = readw(ofsAddr + FlagStat) >> 4;
-       }
        val &= 0x0B;
        if (val & 8)
                val |= 4;