8250: add support for ASIX devices with a FIFO bug

Information and a different patch provided by <donald@asix.com.tw>. We do
it a little differently to keep the modularity and to avoid playing with
RLSI.

We add a new uart bug for the parity flaw and set it in the pci matches.
If parity check is enabled then we drop the FIFO trigger to 1 as per the
Asix reference code.

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

3 files changed, 28 insertions, 5 deletions

diff --git a/drivers/tty/serial/8250/8250.c b/drivers/tty/serial/8250/8250.c
index ca42d16e5a12..44f52c6f15b9 100644
--- a/drivers/tty/serial/8250/8250.c
+++ b/drivers/tty/serial/8250/8250.c
@@ -2202,6 +2202,7 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
         unsigned char cval, fcr = 0;
         unsigned long flags;
         unsigned int baud, quot;
+        int fifo_bug = 0;
 
         switch (termios->c_cflag & CSIZE) {
         case CS5:
@@ -2221,8 +2222,11 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
 
         if (termios->c_cflag & CSTOPB)
                 cval |= UART_LCR_STOP;
-        if (termios->c_cflag & PARENB)
+        if (termios->c_cflag & PARENB) {
                 cval |= UART_LCR_PARITY;
+                if (up->bugs & UART_BUG_PARITY)
+                        fifo_bug = 1;
+        }
         if (!(termios->c_cflag & PARODD))
                 cval |= UART_LCR_EPAR;
 #ifdef CMSPAR
@@ -2246,7 +2250,7 @@ serial8250_do_set_termios(struct uart_port *port, struct ktermios *termios,
 
         if (up->capabilities & UART_CAP_FIFO && port->fifosize > 1) {
                 fcr = uart_config[port->type].fcr;
-                if (baud < 2400) {
+                if (baud < 2400 || fifo_bug) {
                         fcr &= ~UART_FCR_TRIGGER_MASK;
                         fcr |= UART_FCR_TRIGGER_1;
                 }
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index f9719d167c8d..c335b2b23a5f 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -78,6 +78,7 @@ struct serial8250_config {
 #define UART_BUG_TXEN   (1 << 1)        /* UART has buggy TX IIR status */
 #define UART_BUG_NOMSR  (1 << 2)        /* UART has buggy MSR status bits (Au1x00) */
 #define UART_BUG_THRE   (1 << 3)        /* UART has buggy THRE reassertion */
+#define UART_BUG_PARITY (1 << 4)        /* UART mishandles parity if FIFO enabled */
 
 #define PROBE_RSA       (1 << 0)
 #define PROBE_ANY       (~0)
diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index 2ef9a075eec5..62e10fe747a8 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -1032,8 +1032,15 @@ static int pci_oxsemi_tornado_init(struct pci_dev *dev)
         return number_uarts;
 }
 
-static int
-pci_default_setup(struct serial_private *priv,
+static int pci_asix_setup(struct serial_private *priv,
+                  const struct pciserial_board *board,
+                  struct uart_8250_port *port, int idx)
+{
+        port->bugs |= UART_BUG_PARITY;
+        return pci_default_setup(priv, board, port, idx);
+}
+
+static int pci_default_setup(struct serial_private *priv,
                   const struct pciserial_board *board,
                   struct uart_8250_port *port, int idx)
 {
@@ -1187,6 +1194,7 @@ pci_xr17c154_setup(struct serial_private *priv,
 #define PCIE_DEVICE_ID_NEO_2_OX_IBM     0x00F6
 #define PCI_DEVICE_ID_PLX_CRONYX_OMEGA  0xc001
 #define PCI_DEVICE_ID_INTEL_PATSBURG_KT 0x1d3d
+#define PCI_VENDOR_ID_ASIX              0x9710
 
 /* Unknown vendors/cards - this should not be in linux/pci_ids.h */
 #define PCI_SUBDEVICE_ID_UNKNOWN_0x1584 0x1584
@@ -1726,7 +1734,17 @@ static struct pci_serial_quirk pci_serial_quirks[] __refdata = {
                 .subvendor      = PCI_ANY_ID,
                 .subdevice      = PCI_ANY_ID,
                 .setup          = pci_omegapci_setup,
-         },
+        },
+        /*
+         * ASIX devices with FIFO bug
+         */
+        {
+                .vendor         = PCI_VENDOR_ID_ASIX,
+                .device         = PCI_ANY_ID,
+                .subvendor      = PCI_ANY_ID,
+                .subdevice      = PCI_ANY_ID,
+                .setup          = pci_asix_setup,
+        },
         /*
          * Default "match everything" terminator entry
          */