dz: handle special conditions on reception correctly

Handle the read and ignore status masks correctly.  Handle the BREAK condition
as expected: a framing error with a null character is a BREAK, any other
framing error is a framing error indeed.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 46 insertions, 38 deletions

diff --git a/drivers/serial/dz.c b/drivers/serial/dz.c
index 656c342a80f8..ae3203b20134 100644
--- a/drivers/serial/dz.c
+++ b/drivers/serial/dz.c
@@ -166,6 +166,7 @@ static void dz_enable_ms(struct uart_port *port)
  */
 static inline void dz_receive_chars(struct dz_port *dport_in)
 {
+        struct uart_port *uport;
         struct dz_port *dport;
         struct tty_struct *tty = NULL;
         struct uart_icount *icount;
@@ -176,57 +177,56 @@ static inline void dz_receive_chars(struct dz_port *dport_in)
 
         while ((status = dz_in(dport_in, DZ_RBUF)) & DZ_DVAL) {
                 dport = &dz_ports[LINE(status)];
-                tty = dport->port.info->tty;    /* point to the proper dev */
+                uport = &dport->port;
+                tty = uport->info->tty;         /* point to the proper dev */
 
                 ch = UCHAR(status);             /* grab the char */
+                flag = TTY_NORMAL;
 
-                icount = &dport->port.icount;
+                icount = &uport->icount;
                 icount->rx++;
 
-                flag = TTY_NORMAL;
-                if (status & DZ_FERR) {         /* frame error */
+                if (unlikely(status & (DZ_OERR | DZ_FERR | DZ_PERR))) {
+
                         /*
-                         * There is no separate BREAK status bit, so
-                         * treat framing errors as BREAKs for Magic SysRq
-                         * and SAK; normally, otherwise.
+                         * There is no separate BREAK status bit, so treat
+                         * null characters with framing errors as BREAKs;
+                         * normally, otherwise.  For this move the Framing
+                         * Error bit to a simulated BREAK bit.
                          */
-                        if (uart_handle_break(&dport->port))
-                                continue;
-                        if (dport->port.flags & UPF_SAK)
+                        if (!ch) {
+                                status |= (status & DZ_FERR) >>
+                                          (ffs(DZ_FERR) - ffs(DZ_BREAK));
+                                status &= ~DZ_FERR;
+                        }
+
+                        /* Handle SysRq/SAK & keep track of the statistics. */
+                        if (status & DZ_BREAK) {
+                                icount->brk++;
+                                if (uart_handle_break(uport))
+                                        continue;
+                        } else if (status & DZ_FERR)
+                                icount->frame++;
+                        else if (status & DZ_PERR)
+                                icount->parity++;
+                        if (status & DZ_OERR)
+                                icount->overrun++;
+
+                        status &= uport->read_status_mask;
+                        if (status & DZ_BREAK)
                                 flag = TTY_BREAK;
-                        else
+                        else if (status & DZ_FERR)
                                 flag = TTY_FRAME;
-                } else if (status & DZ_OERR)    /* overrun error */
-                        flag = TTY_OVERRUN;
-                else if (status & DZ_PERR)      /* parity error */
-                        flag = TTY_PARITY;
-
-                /* keep track of the statistics */
-                switch (flag) {
-                case TTY_FRAME:
-                        icount->frame++;
-                        break;
-                case TTY_PARITY:
-                        icount->parity++;
-                        break;
-                case TTY_OVERRUN:
-                        icount->overrun++;
-                        break;
-                case TTY_BREAK:
-                        icount->brk++;
-                        break;
-                default:
-                        break;
+                        else if (status & DZ_PERR)
+                                flag = TTY_PARITY;
+
                 }
 
-                if (uart_handle_sysrq_char(&dport->port, ch))
+                if (uart_handle_sysrq_char(uport, ch))
                         continue;
 
-                if ((status & dport->port.ignore_status_mask) == 0) {
-                        uart_insert_char(&dport->port,
-                                         status, DZ_OERR, ch, flag);
-                        lines_rx[LINE(status)] = 1;
-                }
+                uart_insert_char(uport, status, DZ_OERR, ch, flag);
+                lines_rx[LINE(status)] = 1;
         }
         for (i = 0; i < DZ_NB_PORT; i++)
                 if (lines_rx[i])
@@ -556,11 +556,17 @@ static void dz_set_termios(struct uart_port *uport, struct ktermios *termios,
         dport->port.read_status_mask = DZ_OERR;
         if (termios->c_iflag & INPCK)
                 dport->port.read_status_mask |= DZ_FERR | DZ_PERR;
+        if (termios->c_iflag & (BRKINT | PARMRK))
+                dport->port.read_status_mask |= DZ_BREAK;
 
         /* characters to ignore */
         uport->ignore_status_mask = 0;
+        if ((termios->c_iflag & (IGNPAR | IGNBRK)) == (IGNPAR | IGNBRK))
+                dport->port.ignore_status_mask |= DZ_OERR;
         if (termios->c_iflag & IGNPAR)
                 dport->port.ignore_status_mask |= DZ_FERR | DZ_PERR;
+        if (termios->c_iflag & IGNBRK)
+                dport->port.ignore_status_mask |= DZ_BREAK;
 
         spin_unlock_irqrestore(&dport->port.lock, flags);
 }
diff --git a/drivers/serial/dz.h b/drivers/serial/dz.h
index 6b34d50bf42d..1e836c3411d4 100644
--- a/drivers/serial/dz.h
+++ b/drivers/serial/dz.h
@@ -33,6 +33,8 @@
 #define DZ_FERR        0x2000                 /* Frame error indicator */
 #define DZ_PERR        0x1000                 /* Parity error indicator */
 
+#define DZ_BREAK       0x0800                 /* BREAK event software flag */
+
 #define LINE(x) ((x & DZ_LINE_MASK) >> 8)     /* Get the line number
                                                  from the input buffer */
 #define UCHAR(x) ((unsigned char)(x & DZ_RBUF_MASK))