This improves the performance of U-Boot when accepting rapid input,
such as pasting a sequence of commands.
Without this patch, on P4080DS I see a maximum of around 5 mw.l lines can
be pasted. With this patch, it handles around 70 lines before lossage,
long enough for most things you'd paste.
Signed-off-by: Scott Wood <scottwood at freescale.com>
---
README | 8 ++++
drivers/serial/ns16550.c | 96 +++++++++++++++++++++++++++++++++++++++++++--
drivers/serial/serial.c | 4 +-
include/ns16550.h | 4 +-
4 files changed, 103 insertions(+), 9 deletions(-)
diff --git a/README b/README
index bd03523..d21ea9c 100644
--- a/README
+++ b/README
@@ -2682,6 +2682,14 @@ use the "saveenv" command to store a valid environment.
space for already greatly restricted images, including but not
limited to NAND_SPL configurations.
+- CONFIG_NS16550_BUFFER_READS:
+ Instead of reading directly from the receive register
+ every time U-Boot is ready for another byte, keep a
+ buffer and fill it from the hardware fifo every time
+ U-Boot reads a character. This helps U-Boot keep up with
+ a larger amount of rapid input, such as happens when
+ pasting text into the terminal.
+
Low Level (hardware related) configuration options:
---------------------------------------------------
diff --git a/drivers/serial/ns16550.c b/drivers/serial/ns16550.c
index 8eeb48f..ed3428d 100644
--- a/drivers/serial/ns16550.c
+++ b/drivers/serial/ns16550.c
@@ -4,12 +4,15 @@
* modified to use CONFIG_SYS_ISA_MEM and new defines
*/
+#include <common.h>
#include <config.h>
#include <ns16550.h>
#include <watchdog.h>
#include <linux/types.h>
#include <asm/io.h>
+DECLARE_GLOBAL_DATA_PTR;
+
#define UART_LCRVAL UART_LCR_8N1 /* 8 data, 1 stop, no parity */
#define UART_MCRVAL (UART_MCR_DTR | \
UART_MCR_RTS) /* RTS/DTR */
@@ -86,21 +89,104 @@ void NS16550_putc (NS16550_t com_port, char c)
}
#ifndef CONFIG_NS16550_MIN_FUNCTIONS
-char NS16550_getc (NS16550_t com_port)
+
+static char NS16550_raw_getc(NS16550_t regs)
{
- while ((serial_in(&com_port->lsr) & UART_LSR_DR) == 0) {
+ while ((serial_in(®s->lsr) & UART_LSR_DR) == 0) {
#ifdef CONFIG_USB_TTY
extern void usbtty_poll(void);
usbtty_poll();
#endif
WATCHDOG_RESET();
}
- return serial_in(&com_port->rbr);
+ return serial_in(®s->rbr);
+}
+
+static int NS16550_raw_tstc(NS16550_t regs)
+{
+ return ((serial_in(®s->lsr) & UART_LSR_DR) != 0);
+}
+
+
+#ifdef CONFIG_NS16550_BUFFER_READS
+
+#define BUF_SIZE 256
+#define NUM_PORTS 4
+
+struct ns16550_priv {
+ char buf[BUF_SIZE];
+ unsigned int head, tail;
+};
+
+static struct ns16550_priv rxstate[NUM_PORTS];
+
+static void enqueue(unsigned int port, char ch)
+{
+ /* If queue is full, drop the character. */
+ if ((rxstate[port].head - rxstate[port].tail - 1) % BUF_SIZE == 0)
+ return;
+
+ rxstate[port].buf[rxstate[port].tail] = ch;
+ rxstate[port].tail = (rxstate[port].tail + 1) % BUF_SIZE;
+}
+
+static int dequeue(unsigned int port, char *ch)
+{
+ /* Empty queue? */
+ if (rxstate[port].head == rxstate[port].tail)
+ return 0;
+
+ *ch = rxstate[port].buf[rxstate[port].head];
+ rxstate[port].head = (rxstate[port].head + 1) % BUF_SIZE;
+ return 1;
+}
+
+static void fill_rx_buf(NS16550_t regs, unsigned int port)
+{
+ while ((serial_in(®s->lsr) & UART_LSR_DR) != 0)
+ enqueue(port, serial_in(®s->rbr));
+}
+
+char NS16550_getc(NS16550_t regs, unsigned int port)
+{
+ char ch;
+
+ if (port >= NUM_PORTS || !(gd->flags & GD_FLG_RELOC))
+ return NS16550_raw_getc(regs);
+
+ do {
+#ifdef CONFIG_USB_TTY
+ extern void usbtty_poll(void);
+ usbtty_poll();
+#endif
+ fill_rx_buf(regs, port);
+ WATCHDOG_RESET();
+ } while (!dequeue(port, &ch));
+
+ return ch;
+}
+
+int NS16550_tstc(NS16550_t regs, unsigned int port)
+{
+ if (port >= NUM_PORTS || !(gd->flags & GD_FLG_RELOC))
+ return NS16550_raw_tstc(regs);
+
+ fill_rx_buf(regs, port);
+
+ return rxstate[port].head != rxstate[port].tail;
+}
+
+#else /* CONFIG_NS16550_BUFFER_READS */
+
+char NS16550_getc(NS16550_t regs, unsigned int port)
+{
+ return NS16550_raw_getc(regs);
}
-int NS16550_tstc (NS16550_t com_port)
+int NS16550_tstc(NS16550_t regs, unsigned int port)
{
- return ((serial_in(&com_port->lsr) & UART_LSR_DR) != 0);
+ return NS16550_raw_tstc(regs);
}
+#endif /* CONFIG_NS16550_BUFFER_READS */
#endif /* CONFIG_NS16550_MIN_FUNCTIONS */
diff --git a/drivers/serial/serial.c b/drivers/serial/serial.c
index 4032dfd..3fc80b1 100644
--- a/drivers/serial/serial.c
+++ b/drivers/serial/serial.c
@@ -219,13 +219,13 @@ _serial_puts (const char *s,const int port)
int
_serial_getc(const int port)
{
- return NS16550_getc(PORT);
+ return NS16550_getc(PORT, port);
}
int
_serial_tstc(const int port)
{
- return NS16550_tstc(PORT);
+ return NS16550_tstc(PORT, port);
}
void
diff --git a/include/ns16550.h b/include/ns16550.h
index 9ea81e9..fa3e62e 100644
--- a/include/ns16550.h
+++ b/include/ns16550.h
@@ -160,6 +160,6 @@ typedef volatile struct NS16550 *NS16550_t;
void NS16550_init (NS16550_t com_port, int baud_divisor);
void NS16550_putc (NS16550_t com_port, char c);
-char NS16550_getc (NS16550_t com_port);
-int NS16550_tstc (NS16550_t com_port);
+char NS16550_getc (NS16550_t regs, unsigned int port);
+int NS16550_tstc (NS16550_t regs, unsigned int port);
void NS16550_reinit (NS16550_t com_port, int baud_divisor);
--
1.7.1