On Tue, Mar 01, 2022 at 01:41:10PM +0000, Visa Hankala wrote:
> On Tue, Mar 01, 2022 at 07:08:51AM +0100, Anton Lindqvist wrote:
> > On Sun, Feb 27, 2022 at 05:33:17PM +0100, Mark Kettenis wrote:
> > > > Date: Sun, 27 Feb 2022 16:01:25 +0100
> > > > From: Anton Lindqvist <an...@basename.se>
> > > >
>
> > > > r1p5 is revision 3 with a 32 bytes FIFO. My only concern is that the
> > > > following registers which this diff makes use of are not enumerated in
> > > > the "Base UART Register Set" listing:
> > > >
> > > > 1. UARTPeriphID2 - used to deduce the revision
> > > > 2. UARTIFLS - interrupt FIFO level select register
> > >
> > > Right. So you can't really use those registers, at least not
> > > unconditionally.
> > >
> > > What we could do is add a flag to the softc to indicate that we're
> > > dealing with an SBSA UART instead of a genuine PL011 UART. This would
> > > skip reading the UARTPeriphID2 (assuming r1p5 properties) and skip
> > > touching UARTIFLS (and perhaps some other potentially unimplemented
> > > registers).
> > >
> > > We would set this flag based on the compatible string in pluart_fdt.c
> > > and based on the _HID (or maybe even unconditionally) in
> > > pluart_acpi.c.
> >
> > Here's a first stab at handling such devices. Attaching over ACPI also
> > keeps the FIFO disabled.
> >
> > diff --git sys/dev/fdt/pluart_fdt.c sys/dev/fdt/pluart_fdt.c
> > index 7f17365f1d6..45e31f9872f 100644
> > --- sys/dev/fdt/pluart_fdt.c
> > +++ sys/dev/fdt/pluart_fdt.c
> > @@ -69,6 +69,16 @@ pluart_fdt_attach(struct device *parent, struct device
> > *self, void *aux)
> > return;
> > }
> >
> > + /*
> > + * The SBSA UART is PL011 r1p5 compliant which implies revision 3 with a
> > + * 32 byte FIFO. However, we cannot expect to configure RX/TX interrupt
> > + * levels using the UARTIFLS register making it impossible to make
> > + * assumptions about the number of available bytes in the FIFO.
> > + * Therefore disable FIFO support for such devices.
> > + */
> > + if (!OF_is_compatible(faa->fa_node, "arm,sbsa-uart"))
> > + sc->sc_hwflags |= COM_HW_FIFO;
> > +
>
> Could this piece of code use a dedicated flag, say COM_HW_SBSA (or
> inversely COM_HW_PL011), that tells that the UART is an SBSA UART (or
> true PL011 UART).
>
> To me, this use of the COM_HW_FIFO is a bit obscure; you need to look
> at the comment in pluart_fdt_attach() to understand the logic.
New diff replacing usage of COM_HW_FIFO with COM_HW_SBSA.
> Is worrying about the exact size of the FIFO really worthwhile? As I
> suggested earlier, pluart_start() could check the TXFF flag in the
> Flag Register before feeding each byte to the FIFO. This would allow
> the same transmit code apply to both SBSA and true PL011 UARTs.
>
> The SBSA UART interface does not have the IFLS register. However, it
> looks that the FIFO and the interrupt are usable nevertheless. At least
> Linux appears to enable them.
I did look at Linux as well. They do not initialize the ifls field for
SBSA devices causing 0 to be written to the UARTIFLS register which
implies an interrupt level of 1/8 for both RX and TX. However, it's
still unknown whenever this have any effect or not.
diff --git sys/dev/acpi/pluart_acpi.c sys/dev/acpi/pluart_acpi.c
index dc8ea5e9922..08ebe13ffbc 100644
--- sys/dev/acpi/pluart_acpi.c
+++ sys/dev/acpi/pluart_acpi.c
@@ -91,6 +91,8 @@ pluart_acpi_attach(struct device *parent, struct device
*self, void *aux)
return;
}
+ sc->sc.sc_hwflags |= COM_HW_SBSA;
+
pluart_attach_common(&sc->sc, pluart_acpi_is_console(sc));
}
diff --git sys/dev/fdt/pluart_fdt.c sys/dev/fdt/pluart_fdt.c
index 7f17365f1d6..798250593bf 100644
--- sys/dev/fdt/pluart_fdt.c
+++ sys/dev/fdt/pluart_fdt.c
@@ -69,6 +69,9 @@ pluart_fdt_attach(struct device *parent, struct device *self,
void *aux)
return;
}
+ if (OF_is_compatible(faa->fa_node, "arm,sbsa-uart"))
+ sc->sc_hwflags |= COM_HW_SBSA;
+
sc->sc_irq = fdt_intr_establish(faa->fa_node, IPL_TTY, pluart_intr,
sc, sc->sc_dev.dv_xname);
diff --git sys/dev/ic/pluart.c sys/dev/ic/pluart.c
index eaa11b6c44b..61233290e0d 100644
--- sys/dev/ic/pluart.c
+++ sys/dev/ic/pluart.c
@@ -99,6 +99,13 @@
#define UART_CR_CTSE (1 << 14) /* CTS hardware flow control
enable */
#define UART_CR_RTSE (1 << 15) /* RTS hardware flow control
enable */
#define UART_IFLS 0x34 /* Interrupt FIFO level select
register */
+#define UART_IFLS_RX_SHIFT 3 /* RX level in bits [5:3] */
+#define UART_IFLS_TX_SHIFT 0 /* TX level in bits [2:0] */
+#define UART_IFLS_1_8 0 /* FIFO 1/8 full */
+#define UART_IFLS_1_4 1 /* FIFO 1/4 full */
+#define UART_IFLS_1_2 2 /* FIFO 1/2 full */
+#define UART_IFLS_3_4 3 /* FIFO 3/4 full */
+#define UART_IFLS_7_8 4 /* FIFO 7/8 full */
#define UART_IMSC 0x38 /* Interrupt mask set/clear
register */
#define UART_IMSC_RIMIM (1 << 0)
#define UART_IMSC_CTSMIM (1 << 1)
@@ -115,8 +122,16 @@
#define UART_MIS 0x40 /* Masked interrupt status
register */
#define UART_ICR 0x44 /* Interrupt clear register */
#define UART_DMACR 0x48 /* DMA control register */
+#define UART_PID0 0xfe0 /* Peripheral identification
register 0 */
+#define UART_PID1 0xfe4 /* Peripheral identification
register 1 */
+#define UART_PID2 0xfe8 /* Peripheral identification
register 2 */
+#define UART_PID2_REV(x) (((x) & 0xf0) >> 4)
+#define UART_PID3 0xfec /* Peripheral identification
register 3 */
#define UART_SPACE 0x100
+#define UART_FIFO_SIZE 16
+#define UART_FIFO_SIZE_R3 32
+
void pluartcnprobe(struct consdev *cp);
void pluartcninit(struct consdev *cp);
int pluartcngetc(dev_t dev);
@@ -150,7 +165,31 @@ struct cdevsw pluartdev =
void
pluart_attach_common(struct pluart_softc *sc, int console)
{
- int maj;
+ int fifolen, maj;
+ int lcr;
+
+ if ((sc->sc_hwflags & COM_HW_SBSA) == 0) {
+ int rev;
+
+ rev = UART_PID2_REV(bus_space_read_4(sc->sc_iot, sc->sc_ioh,
+ UART_PID2));
+ if (rev < 3)
+ fifolen = UART_FIFO_SIZE;
+ else
+ fifolen = UART_FIFO_SIZE_R3;
+ printf(": rev %d, %d byte fifo\n", rev, fifolen);
+ } else {
+ /*
+ * The SBSA UART is PL011 r1p5 compliant which implies revision
+ * 3 with a 32 byte FIFO. However, we cannot expect to configure
+ * RX/TX interrupt levels using the UARTIFLS register making it
+ * impossible to make assumptions about the number of available
+ * bytes in the FIFO. Therefore disable FIFO support for such
+ * devices.
+ */
+ fifolen = 0;
+ printf("\n");
+ }
if (console) {
/* Locate the major number. */
@@ -159,7 +198,7 @@ pluart_attach_common(struct pluart_softc *sc, int console)
break;
cn_tab->cn_dev = makedev(maj, sc->sc_dev.dv_unit);
- printf(": console");
+ printf("%s: console\n", sc->sc_dev.dv_xname);
SET(sc->sc_hwflags, COM_HW_CONSOLE);
}
@@ -171,13 +210,28 @@ pluart_attach_common(struct pluart_softc *sc, int console)
panic("%s: can't establish soft interrupt.",
sc->sc_dev.dv_xname);
- bus_space_write_4(sc->sc_iot, sc->sc_ioh, UART_IMSC, (UART_IMSC_RXIM |
UART_IMSC_TXIM));
+ if (fifolen > 0) {
+ /*
+ * The transmit FIFO size is set to 3/4 of the actual size as
+ * interrupts can only be triggered when the FIFO is partially
+ * full. Once triggered, we know that 1/4 of the FIFO size is
+ * utilized.
+ */
+ sc->sc_fifolen = (fifolen * 3)/4;
+ bus_space_write_4(sc->sc_iot, sc->sc_ioh, UART_IFLS,
+ (UART_IFLS_3_4 << UART_IFLS_RX_SHIFT) |
+ (UART_IFLS_1_4 << UART_IFLS_TX_SHIFT));
+ }
+ sc->sc_imsc = UART_IMSC_RXIM | UART_IMSC_RTIM | UART_IMSC_TXIM;
+ bus_space_write_4(sc->sc_iot, sc->sc_ioh, UART_IMSC, sc->sc_imsc);
bus_space_write_4(sc->sc_iot, sc->sc_ioh, UART_ICR, 0x7ff);
- bus_space_write_4(sc->sc_iot, sc->sc_ioh, UART_LCR_H,
- bus_space_read_4(sc->sc_iot, sc->sc_ioh, UART_LCR_H) &
- ~UART_LCR_H_FEN);
-
- printf("\n");
+ lcr = bus_space_read_4(sc->sc_iot, sc->sc_ioh, UART_LCR_H);
+ if (fifolen > 0) {
+ lcr |= UART_LCR_H_FEN;
+ } else {
+ lcr &= ~UART_LCR_H_FEN;
+ }
+ bus_space_write_4(sc->sc_iot, sc->sc_ioh, UART_LCR_H, lcr);
}
int
@@ -197,19 +251,26 @@ pluart_intr(void *arg)
if (sc->sc_tty == NULL)
return 0;
- if (!ISSET(is, UART_IMSC_RXIM) && !ISSET(is, UART_IMSC_TXIM))
+ if (!ISSET(is, UART_IMSC_RXIM) && !ISSET(is, UART_IMSC_RTIM) &&
+ !ISSET(is, UART_IMSC_TXIM))
return 0;
- if (ISSET(is, UART_IMSC_TXIM) && ISSET(tp->t_state, TS_BUSY)) {
- CLR(tp->t_state, TS_BUSY | TS_FLUSH);
- if (sc->sc_halt > 0)
- wakeup(&tp->t_outq);
- (*linesw[tp->t_line].l_start)(tp);
+ if (ISSET(is, UART_IMSC_TXIM)) {
+ /* Disable transmit interrupt. */
+ bus_space_write_4(sc->sc_iot, sc->sc_ioh, UART_IMSC,
+ sc->sc_imsc & ~UART_IMSC_TXIM);
+
+ if (ISSET(tp->t_state, TS_BUSY)) {
+ CLR(tp->t_state, TS_BUSY | TS_FLUSH);
+ if (sc->sc_halt > 0)
+ wakeup(&tp->t_outq);
+ (*linesw[tp->t_line].l_start)(tp);
+ }
}
p = sc->sc_ibufp;
- while (ISSET(bus_space_read_4(iot, ioh, UART_FR), UART_FR_RXFF)) {
+ while (!ISSET(bus_space_read_4(iot, ioh, UART_FR), UART_FR_RXFE)) {
c = bus_space_read_2(iot, ioh, UART_DR);
if (c & UART_DR_BE) {
#ifdef DDB
@@ -325,7 +386,6 @@ pluart_start(struct tty *tp)
struct pluart_softc *sc = pluart_cd.cd_devs[DEVUNIT(tp->t_dev)];
bus_space_tag_t iot = sc->sc_iot;
bus_space_handle_t ioh = sc->sc_ioh;
- u_int16_t fr;
int s;
s = spltty();
@@ -336,11 +396,26 @@ pluart_start(struct tty *tp)
goto out;
SET(tp->t_state, TS_BUSY);
- fr = bus_space_read_4(iot, ioh, UART_FR);
- while (tp->t_outq.c_cc != 0 && ISSET(fr, UART_FR_TXFE)) {
- bus_space_write_4(iot, ioh, UART_DR, getc(&tp->t_outq));
+ /* Enable transmit interrupt. */
+ bus_space_write_4(sc->sc_iot, sc->sc_ioh, UART_IMSC, sc->sc_imsc);
+
+ if ((sc->sc_hwflags & COM_HW_SBSA) == 0) {
+ char buf[UART_FIFO_SIZE_R3]; /* fifo max size */
+ int i, n;
+
+ n = q_to_b(&tp->t_outq, buf, sc->sc_fifolen);
+ for (i = 0; i < n; i++)
+ bus_space_write_4(iot, ioh, UART_DR, buf[i]);
+ } else {
+ u_int16_t fr;
+
fr = bus_space_read_4(iot, ioh, UART_FR);
+ while (tp->t_outq.c_cc != 0 && ISSET(fr, UART_FR_TXFE)) {
+ bus_space_write_4(iot, ioh, UART_DR, getc(&tp->t_outq));
+ fr = bus_space_read_4(iot, ioh, UART_FR);
+ }
}
+
out:
splx(s);
}
diff --git sys/dev/ic/pluartvar.h sys/dev/ic/pluartvar.h
index 8fcbed14d5c..ba9748286ba 100644
--- sys/dev/ic/pluartvar.h
+++ sys/dev/ic/pluartvar.h
@@ -38,6 +38,7 @@ struct pluart_softc {
#define COM_HW_FIFO 0x02
#define COM_HW_SIR 0x20
#define COM_HW_CONSOLE 0x40
+#define COM_HW_SBSA 0x80
u_int8_t sc_swflags;
#define COM_SW_SOFTCAR 0x01
#define COM_SW_CLOCAL 0x02
@@ -45,6 +46,7 @@ struct pluart_softc {
#define COM_SW_MDMBUF 0x08
#define COM_SW_PPS 0x10
int sc_fifolen;
+ int sc_imsc;
u_int8_t sc_initialize;
u_int8_t sc_cua;
