serial: sh-sci: SCIFA/B RX FIFO software timeout

Implements support for FIFO fill thresholds greater than one with software
timeout.

This mechanism is not possible (or at least not useful) on SCIF family
hardware other than SCIFA and SCIFB because they do not support turning off
the DR hardware timeout interrupt separately from the RI interrupt.

Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 520e344a811df2c4f3bf109ccf8cd78390b468c7..4a165ed1bc3fb88860924bd075071f92846ec848 100644 (file)
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -148,7 +148,10 @@ struct sci_port {
        struct timer_list               rx_timer;
        unsigned int                    rx_timeout;
 #endif
+       unsigned int                    rx_frame;
        int                             rx_trigger;
+       struct timer_list               rx_fifo_timer;
+       int                             rx_fifo_timeout;
 
        bool has_rtscts;
        bool autorts;
@@ -1034,6 +1037,24 @@ static int scif_set_rtrg(struct uart_port *port, int rx_trig)
        return rx_trig;
 }
 
+static int scif_rtrg_enabled(struct uart_port *port)
+{
+       if (sci_getreg(port, HSRTRGR)->size)
+               return serial_port_in(port, HSRTRGR) != 0;
+       else
+               return (serial_port_in(port, SCFCR) &
+                       (SCFCR_RTRG0 | SCFCR_RTRG1)) != 0;
+}
+
+static void rx_fifo_timer_fn(unsigned long arg)
+{
+       struct sci_port *s = (struct sci_port *)arg;
+       struct uart_port *port = &s->port;
+
+       dev_dbg(port->dev, "Rx timed out\n");
+       scif_set_rtrg(port, 1);
+}
+
 #ifdef CONFIG_SERIAL_SH_SCI_DMA
 static void sci_dma_tx_complete(void *arg)
 {
@@ -1473,10 +1494,10 @@ static inline void sci_free_dma(struct uart_port *port)
 
 static irqreturn_t sci_rx_interrupt(int irq, void *ptr)
 {
-#ifdef CONFIG_SERIAL_SH_SCI_DMA
        struct uart_port *port = ptr;
        struct sci_port *s = to_sci_port(port);
 
+#ifdef CONFIG_SERIAL_SH_SCI_DMA
        if (s->chan_rx) {
                u16 scr = serial_port_in(port, SCSCR);
                u16 ssr = serial_port_in(port, SCxSR);
@@ -1501,6 +1522,14 @@ static irqreturn_t sci_rx_interrupt(int irq, void *ptr)
        }
 #endif
 
+       if (s->rx_trigger > 1 && s->rx_fifo_timeout > 0) {
+               if (!scif_rtrg_enabled(port))
+                       scif_set_rtrg(port, s->rx_trigger);
+
+               mod_timer(&s->rx_fifo_timer, jiffies + DIV_ROUND_UP(
+                         s->rx_frame * s->rx_fifo_timeout, 1000));
+       }
+
        /* I think sci_receive_chars has to be called irrespective
         * of whether the I_IXOFF is set, otherwise, how is the interrupt
         * to be disabled?
@@ -2084,14 +2113,21 @@ static void sci_reset(struct uart_port *port)
                serial_port_out(port, SCLSR, status);
        }
 
-       if (s->rx_trigger > 1)
-               scif_set_rtrg(port, s->rx_trigger);
+       if (s->rx_trigger > 1) {
+               if (s->rx_fifo_timeout) {
+                       scif_set_rtrg(port, 1);
+                       setup_timer(&s->rx_fifo_timer, rx_fifo_timer_fn,
+                                   (unsigned long)s);
+               } else {
+                       scif_set_rtrg(port, s->rx_trigger);
+               }
+       }
 }
 
 static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
                            struct ktermios *old)
 {
-       unsigned int baud, smr_val = SCSMR_ASYNC, scr_val = 0, i;
+       unsigned int baud, smr_val = SCSMR_ASYNC, scr_val = 0, i, bits;
        unsigned int brr = 255, cks = 0, srr = 15, dl = 0, sccks = 0;
        unsigned int brr1 = 255, cks1 = 0, srr1 = 15, dl1 = 0;
        struct sci_port *s = to_sci_port(port);
@@ -2287,7 +2323,6 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
                udelay(DIV_ROUND_UP(10 * 1000000, baud));
        }
 
-#ifdef CONFIG_SERIAL_SH_SCI_DMA
        /*
         * Calculate delay for 2 DMA buffers (4 FIFO).
         * See serial_core.c::uart_update_timeout().
@@ -2298,36 +2333,34 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
         * value obtained by this formula is too small. Therefore, if the value
         * is smaller than 20ms, use 20ms as the timeout value for DMA.
         */
-       if (s->chan_rx) {
-               unsigned int bits;
+       /* byte size and parity */
+       switch (termios->c_cflag & CSIZE) {
+       case CS5:
+               bits = 7;
+               break;
+       case CS6:
+               bits = 8;
+               break;
+       case CS7:
+               bits = 9;
+               break;
+       default:
+               bits = 10;
+               break;
+       }
 
-               /* byte size and parity */
-               switch (termios->c_cflag & CSIZE) {
-               case CS5:
-                       bits = 7;
-                       break;
-               case CS6:
-                       bits = 8;
-                       break;
-               case CS7:
-                       bits = 9;
-                       break;
-               default:
-                       bits = 10;
-                       break;
-               }
+       if (termios->c_cflag & CSTOPB)
+               bits++;
+       if (termios->c_cflag & PARENB)
+               bits++;
 
-               if (termios->c_cflag & CSTOPB)
-                       bits++;
-               if (termios->c_cflag & PARENB)
-                       bits++;
-               s->rx_timeout = DIV_ROUND_UP((s->buf_len_rx * 2 * bits * HZ) /
-                                            (baud / 10), 10);
-               dev_dbg(port->dev, "DMA Rx t-out %ums, tty t-out %u jiffies\n",
-                       s->rx_timeout * 1000 / HZ, port->timeout);
-               if (s->rx_timeout < msecs_to_jiffies(20))
-                       s->rx_timeout = msecs_to_jiffies(20);
-       }
+       s->rx_frame = (100 * bits * HZ) / (baud / 10);
+#ifdef CONFIG_SERIAL_SH_SCI_DMA
+       s->rx_timeout = DIV_ROUND_UP(s->buf_len_rx * 2 * s->rx_frame, 1000);
+       dev_dbg(port->dev, "DMA Rx t-out %ums, tty t-out %u jiffies\n",
+               s->rx_timeout * 1000 / HZ, port->timeout);
+       if (s->rx_timeout < msecs_to_jiffies(20))
+               s->rx_timeout = msecs_to_jiffies(20);
 #endif
 
        if ((termios->c_cflag & CREAD) != 0)
@@ -2642,6 +2675,8 @@ static int sci_init_single(struct platform_device *dev,
                break;
        }
 
+       sci_port->rx_fifo_timeout = 0;
+
        /* SCIFA on sh7723 and sh7724 need a custom sampling rate that doesn't
         * match the SoC datasheet, this should be investigated. Let platform
         * data override the sampling rate for now.