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>

1 files changed, 22 insertions, 5 deletions

diff --git a/drivers/char/moxa.c b/drivers/char/moxa.c
index d8bcbed6d28d..474d936d3b31 100644
--- 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;