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Diffstat (limited to 'sys/dev/uart/uart_dev_ns8250.c')
-rw-r--r--sys/dev/uart/uart_dev_ns8250.c86
1 files changed, 64 insertions, 22 deletions
diff --git a/sys/dev/uart/uart_dev_ns8250.c b/sys/dev/uart/uart_dev_ns8250.c
index 16c3cb2fc5a9..0f19ede6d9df 100644
--- a/sys/dev/uart/uart_dev_ns8250.c
+++ b/sys/dev/uart/uart_dev_ns8250.c
@@ -77,6 +77,11 @@ static int broken_txfifo = 0;
SYSCTL_INT(_hw, OID_AUTO, broken_txfifo, CTLFLAG_RWTUN,
&broken_txfifo, 0, "UART FIFO has QEMU emulation bug");
+static int uart_noise_threshold = 0;
+SYSCTL_INT(_hw, OID_AUTO, uart_noise_threshold, CTLFLAG_RWTUN,
+ &uart_noise_threshold, 0,
+ "Number of UART RX interrupts where TX is not ready, before data is discarded");
+
/*
* To use early printf on x86, add the following to your kernel config:
*
@@ -126,11 +131,11 @@ ns8250_clrint(struct uart_bas *bas)
}
}
-static int
-ns8250_delay(struct uart_bas *bas)
+static uint32_t
+ns8250_get_divisor(struct uart_bas *bas)
{
- int divisor;
- u_char lcr;
+ uint32_t divisor;
+ uint8_t lcr;
lcr = uart_getreg(bas, REG_LCR);
uart_setreg(bas, REG_LCR, lcr | LCR_DLAB);
@@ -140,6 +145,16 @@ ns8250_delay(struct uart_bas *bas)
uart_setreg(bas, REG_LCR, lcr);
uart_barrier(bas);
+ return (divisor);
+}
+
+static int
+ns8250_delay(struct uart_bas *bas)
+{
+ int divisor;
+
+ divisor = ns8250_get_divisor(bas);
+
/* 1/10th the time to transmit 1 character (estimate). */
if (divisor <= 134)
return (16000000 * divisor / bas->rclk);
@@ -187,7 +202,7 @@ ns8250_drain(struct uart_bas *bas, int what)
while ((uart_getreg(bas, REG_LSR) & LSR_TEMT) == 0 && --limit)
DELAY(delay);
if (limit == 0) {
- /* printf("ns8250: transmitter appears stuck... "); */
+ /* printf("uart: ns8250: transmitter appears stuck... "); */
return (EIO);
}
}
@@ -215,7 +230,7 @@ ns8250_drain(struct uart_bas *bas, int what)
DELAY(delay << 2);
}
if (limit == 0) {
- /* printf("ns8250: receiver appears broken... "); */
+ /* printf("uart: ns8250: receiver appears broken... "); */
return (EIO);
}
}
@@ -250,12 +265,12 @@ ns8250_flush(struct uart_bas *bas, int what)
* https://github.com/rust-vmm/vm-superio/issues/83
*/
lsr = uart_getreg(bas, REG_LSR);
- if (((lsr & LSR_TEMT) == 0) && (what & UART_FLUSH_TRANSMITTER))
+ if (((lsr & LSR_THRE) == 0) && (what & UART_FLUSH_TRANSMITTER))
drain |= UART_DRAIN_TRANSMITTER;
if ((lsr & LSR_RXRDY) && (what & UART_FLUSH_RECEIVER))
drain |= UART_DRAIN_RECEIVER;
if (drain != 0) {
- printf("ns8250: UART FCR is broken\n");
+ printf("uart: ns8250: UART FCR is broken (%#x)\n", drain);
ns8250_drain(bas, drain);
}
}
@@ -284,8 +299,8 @@ ns8250_param(struct uart_bas *bas, int baudrate, int databits, int stopbits,
lcr |= LCR_STOPB;
lcr |= parity << 3;
- /* Set baudrate. */
- if (baudrate > 0) {
+ /* Set baudrate if we know a rclk and both are not 0. */
+ if (baudrate > 0 && bas->rclk > 0) {
divisor = ns8250_divisor(bas->rclk, baudrate);
if (divisor == 0)
return (EINVAL);
@@ -349,10 +364,6 @@ ns8250_init(struct uart_bas *bas, int baudrate, int databits, int stopbits,
{
u_char ier;
- if (bas->rclk == 0)
- bas->rclk = DEFAULT_RCLK;
- ns8250_param(bas, baudrate, databits, stopbits, parity);
-
/* Disable all interrupt sources. */
/*
* We use 0xe0 instead of 0xf0 as the mask because the XScale PXA
@@ -363,6 +374,30 @@ ns8250_init(struct uart_bas *bas, int baudrate, int databits, int stopbits,
uart_setreg(bas, REG_IER, ier);
uart_barrier(bas);
+ /*
+ * Loader tells us to infer the rclk when it sets xo to 0 in
+ * hw.uart.console. We know the baudrate was set by the firmware, so
+ * calculate rclk from baudrate and the divisor register. If 'div' is
+ * actually 0, the resulting 0 value will have us fall back to other
+ * rclk methods.
+ */
+ if (bas->rclk_guess && bas->rclk == 0 && baudrate != 0) {
+ uint32_t div;
+
+ div = ns8250_get_divisor(bas);
+ bas->rclk = baudrate * div * 16;
+ }
+
+ /*
+ * Pick a default because we just don't know. This likely needs future
+ * refinement, but that's hard outside of consoles to know what to use.
+ * But defer as long as possible if there's no defined baud rate.
+ */
+ if (bas->rclk == 0 && baudrate != 0)
+ bas->rclk = DEFAULT_RCLK;
+
+ ns8250_param(bas, baudrate, databits, stopbits, parity);
+
/* Disable the FIFO (if present). */
uart_setreg(bas, REG_FCR, 0);
uart_barrier(bas);
@@ -460,9 +495,11 @@ UART_CLASS(uart_ns8250_class);
static struct acpi_uart_compat_data acpi_compat_data[] = {
{"AMD0020", &uart_ns8250_class, 0, 2, 0, 48000000, UART_F_BUSY_DETECT, "AMD / Synopsys Designware UART"},
{"AMDI0020", &uart_ns8250_class, 0, 2, 0, 48000000, UART_F_BUSY_DETECT, "AMD / Synopsys Designware UART"},
+ {"APMC0D08", &uart_ns8250_class, ACPI_DBG2_16550_COMPATIBLE, 2, 4, 0, 0, "APM compatible UART"},
{"MRVL0001", &uart_ns8250_class, ACPI_DBG2_16550_SUBSET, 2, 0, 200000000, UART_F_BUSY_DETECT, "Marvell / Synopsys Designware UART"},
{"SCX0006", &uart_ns8250_class, 0, 2, 0, 62500000, UART_F_BUSY_DETECT, "SynQuacer / Synopsys Designware UART"},
{"HISI0031", &uart_ns8250_class, 0, 2, 0, 200000000, UART_F_BUSY_DETECT, "HiSilicon / Synopsys Designware UART"},
+ {"INTC1006", &uart_ns8250_class, 0, 2, 0, 25000000, 0, "Intel ARM64 UART"},
{"NXP0018", &uart_ns8250_class, 0, 0, 0, 350000000, UART_F_BUSY_DETECT, "NXP / Synopsys Designware UART"},
{"PNP0500", &uart_ns8250_class, 0, 0, 0, 0, 0, "Standard PC COM port"},
{"PNP0501", &uart_ns8250_class, 0, 0, 0, 0, 0, "16550A-compatible COM port"},
@@ -725,14 +762,7 @@ ns8250_bus_ioctl(struct uart_softc *sc, int request, intptr_t data)
uart_barrier(bas);
break;
case UART_IOCTL_BAUD:
- lcr = uart_getreg(bas, REG_LCR);
- uart_setreg(bas, REG_LCR, lcr | LCR_DLAB);
- uart_barrier(bas);
- divisor = uart_getreg(bas, REG_DLL) |
- (uart_getreg(bas, REG_DLH) << 8);
- uart_barrier(bas);
- uart_setreg(bas, REG_LCR, lcr);
- uart_barrier(bas);
+ divisor = ns8250_get_divisor(bas);
baudrate = (divisor > 0) ? bas->rclk / divisor / 16 : 0;
if (baudrate > 0)
*(int*)data = baudrate;
@@ -987,6 +1017,7 @@ int
ns8250_bus_receive(struct uart_softc *sc)
{
struct uart_bas *bas;
+ struct ns8250_softc *ns8250 = (struct ns8250_softc *)sc;
int xc;
uint8_t lsr;
@@ -998,6 +1029,17 @@ ns8250_bus_receive(struct uart_softc *sc)
sc->sc_rxbuf[sc->sc_rxput] = UART_STAT_OVERRUN;
break;
}
+ /* Filter out possible noise on the line.
+ * Expect that the device should be able to transmit as well as
+ * receive, so if we receive too many characters before transmit
+ * is ready, it's probably noise.
+ */
+ if ((lsr & (LSR_TXRDY | LSR_TEMT)) == 0 &&
+ uart_noise_threshold > 0) {
+ if (++ns8250->noise_count >= uart_noise_threshold)
+ break;
+ } else
+ ns8250->noise_count = 0;
xc = uart_getreg(bas, REG_DATA);
if (lsr & LSR_FE)
xc |= UART_STAT_FRAMERR;
generated by cgit v1.2.3 (git 2.25.1) at 2025-07-06 07:19:34 +0000