Pasting longer lines into the U-Boot console prompt sometimes leads to
characters missing. One problem here is the small 16-byte FIFO of the
legacy NS16550 UART, e.g. on x86 platforms.
This patch now introduces a Kconfig option to enable RX buffer support
for all DM based serial drivers. With this option enabled, I was
able paste really long lines into the U-Boot console, without any
characters missing.
Signed-off-by: Stefan Roese
Cc: Simon Glass
Cc: Bin Meng
Cc: Tom Rini
---
drivers/serial/Kconfig | 15 +
drivers/serial/serial-uclass.c | 48 --
include/serial.h | 10 -
3 files changed, 70 insertions(+), 3 deletions(-)
diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 1c2c5d66e1..aeed538fa4 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -64,6 +64,21 @@ config DM_SERIAL
implements serial_putc() etc. The uclass interface is
defined in include/serial.h.
+config SERIAL_RX_BUFFER
+ bool "Enable RX buffer for serial input"
+ depends on DM_SERIAL
+ help
+ Enable RX buffer support for the serial driver. This enables
+ pasting longer strings, even when the RX FIFO of the UART is
+ not big enough (e.g. 16 bytes on the normal NS16550).
+
+config SERIAL_RX_BUFFER_SIZE
+ int "RX buffer size"
+ depends on SERIAL_RX_BUFFER
+ default 256
+ help
+ The size of the RX buffer (needs to be power of 2)
+
config SPL_DM_SERIAL
bool "Enable Driver Model for serial drivers in SPL"
depends on DM_SERIAL
diff --git a/drivers/serial/serial-uclass.c b/drivers/serial/serial-uclass.c
index 998d372da6..2e5116f7ce 100644
--- a/drivers/serial/serial-uclass.c
+++ b/drivers/serial/serial-uclass.c
@@ -160,7 +160,7 @@ static void _serial_puts(struct udevice *dev, const char
*str)
_serial_putc(dev, *str++);
}
-static int _serial_getc(struct udevice *dev)
+static int __serial_getc(struct udevice *dev)
{
struct dm_serial_ops *ops = serial_get_ops(dev);
int err;
@@ -174,7 +174,7 @@ static int _serial_getc(struct udevice *dev)
return err >= 0 ? err : 0;
}
-static int _serial_tstc(struct udevice *dev)
+static int __serial_tstc(struct udevice *dev)
{
struct dm_serial_ops *ops = serial_get_ops(dev);
@@ -184,6 +184,44 @@ static int _serial_tstc(struct udevice *dev)
return 1;
}
+#if CONFIG_IS_ENABLED(SERIAL_RX_BUFFER)
+static int _serial_tstc(struct udevice *dev)
+{
+ struct serial_dev_priv *upriv = dev_get_uclass_priv(dev);
+
+ /* Read all available chars into the RX buffer */
+ while (__serial_tstc(dev)) {
+ upriv->buf[upriv->wr_ptr++] = __serial_getc(dev);
+ upriv->wr_ptr %= CONFIG_SERIAL_RX_BUFFER_SIZE;
+ }
+
+ return upriv->rd_ptr != upriv->wr_ptr ? 1 : 0;
+}
+
+static int _serial_getc(struct udevice *dev)
+{
+ struct serial_dev_priv *upriv = dev_get_uclass_priv(dev);
+ char val;
+
+ val = upriv->buf[upriv->rd_ptr++];
+ upriv->rd_ptr %= CONFIG_SERIAL_RX_BUFFER_SIZE;
+
+ return val;
+}
+
+#else /* CONFIG_IS_ENABLED(SERIAL_RX_BUFFER) */
+
+static int _serial_getc(struct udevice *dev)
+{
+ return __serial_getc(dev);
+}
+
+static int _serial_tstc(struct udevice *dev)
+{
+ return __serial_tstc(dev);
+}
+#endif /* CONFIG_IS_ENABLED(SERIAL_RX_BUFFER) */
+
void serial_putc(char ch)
{
if (gd->cur_serial_dev)
@@ -359,6 +397,12 @@ static int serial_post_probe(struct udevice *dev)
sdev.puts = serial_stub_puts;
sdev.getc = serial_stub_getc;
sdev.tstc = serial_stub_tstc;
+
+#if CONFIG_IS_ENABLED(SERIAL_RX_BUFFER)
+ /* Allocate the RX buffer */
+ upriv->buf = malloc(CONFIG_SERIAL_RX_BUFFER_SIZE);
+#endif
+
stdio_register_dev(&sdev, &upriv->sdev);
#endif
return 0;
diff --git a/include/serial.h b/include/serial.h
index f4171964ae..d87f01082a 100644
--- a/include/serial.h
+++ b/include/serial.h
@@ -148,10 +148,18 @@ struct dm_serial_ops {
/**
* struct serial_dev_priv - information about a device used by the uclass
*
- * @sdev: stdio device attached to this uart
+ * @sdev: stdio device attached to this uart
+ *
+ * @buf: Pointer to the RX buffer
+ * @rd_ptr:Read pointer in the RX buffer
+ * @wr_ptr:Write pointer in the RX buffer
*/
struct serial_dev_priv {
struct stdio_dev *sdev;
+
+ char *buf;
+ int rd_ptr;
+ int wr_ptr;
};
/* Access the serial operations for a device */
--
2.14.1
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