Hi,
This allows the pluart baud rate to be changed. There's one potential
pitfall with this change as users will have the wrong baud rate in their
/etc/ttys if not installed after revision 1.11 of dev/ic/pluart.c which
landed today. This will make the serial console unusable until the
expected baud rate in /etc/ttys is changed to 115200.
Comments? OK?
diff --git sys/dev/fdt/pluart_fdt.c sys/dev/fdt/pluart_fdt.c
index 969018eccdc..ac2467bdf47 100644
--- sys/dev/fdt/pluart_fdt.c
+++ sys/dev/fdt/pluart_fdt.c
@@ -27,6 +27,7 @@
#include <dev/ofw/fdt.h>
#include <dev/ofw/openfirm.h>
+#include <dev/ofw/ofw_clock.h>
#include <dev/ofw/ofw_pinctrl.h>
int pluart_fdt_match(struct device *, void *, void *);
@@ -70,8 +71,12 @@ pluart_fdt_attach(struct device *parent, struct device
*self, void *aux)
return;
}
- if (OF_is_compatible(faa->fa_node, "arm,sbsa-uart"))
+ if (OF_is_compatible(faa->fa_node, "arm,sbsa-uart")) {
sc->sc_hwflags |= COM_HW_SBSA;
+ } else {
+ clock_enable_all(faa->fa_node);
+ sc->sc_clkfreq = clock_get_frequency(faa->fa_node, "uartclk");
+ }
periphid = OF_getpropint(faa->fa_node, "arm,primecell-periphid", 0);
if (periphid != 0)
diff --git sys/dev/ic/pluart.c sys/dev/ic/pluart.c
index 40e2b1976fb..aa4301e8fb0 100644
--- sys/dev/ic/pluart.c
+++ sys/dev/ic/pluart.c
@@ -71,9 +71,9 @@
#define UART_ILPR 0x20 /* IrDA low-power counter
register */
#define UART_ILPR_ILPDVSR ((x) & 0xf) /* IrDA low-power divisor */
#define UART_IBRD 0x24 /* Integer baud rate register */
-#define UART_IBRD_DIVINT ((x) & 0xff) /* Integer baud rate divisor */
+#define UART_IBRD_DIVINT(x) ((x) & 0xff) /* Integer baud rate divisor */
#define UART_FBRD 0x28 /* Fractional baud rate
register */
-#define UART_FBRD_DIVFRAC ((x) & 0x3f) /* Fractional baud rate divisor
*/
+#define UART_FBRD_DIVFRAC(x) ((x) & 0x3f) /* Fractional baud rate divisor
*/
#define UART_LCR_H 0x2c /* Line control register */
#define UART_LCR_H_BRK (1 << 0) /* Send break */
#define UART_LCR_H_PEN (1 << 1) /* Parity enable */
@@ -338,7 +338,9 @@ pluart_param(struct tty *tp, struct termios *t)
/* lower dtr */
}
- if (ospeed != 0) {
+ if (ospeed != 0 && sc->sc_clkfreq != 0 && tp->t_ospeed != ospeed) {
+ int div, lcr;
+
while (ISSET(tp->t_state, TS_BUSY)) {
++sc->sc_halt;
error = ttysleep(tp, &tp->t_outq,
@@ -349,7 +351,40 @@ pluart_param(struct tty *tp, struct termios *t)
return (error);
}
}
- /* set speed */
+
+ /*
+ * Writes to IBRD and FBRD are made effective first when LCR_H
+ * is written.
+ */
+ lcr = bus_space_read_4(sc->sc_iot, sc->sc_ioh, UART_LCR_H);
+
+ /* The UART must be disabled while changing the baud rate. */
+ bus_space_write_4(sc->sc_iot, sc->sc_ioh, UART_CR, 0);
+
+ /*
+ * The baud rate divisor is expressed relative to the UART clock
+ * frequency where IBRD represents the quotient using 16 bits
+ * and FBRD the remainder using 6 bits. The PL011 specification
+ * provides the following formula:
+ *
+ * uartclk/(16 * baudrate)
+ *
+ * The formula can be estimated by scaling it with the
+ * precision 64 (2^6) and letting the resulting upper 16 bits
+ * represents the quotient and the lower 6 bits the remainder:
+ *
+ * 64 * uartclk/(16 * baudrate) = 4 * uartclk/baudrate
+ */
+ div = 4 * sc->sc_clkfreq / ospeed;
+ bus_space_write_4(sc->sc_iot, sc->sc_ioh, UART_IBRD,
+ UART_IBRD_DIVINT(div >> 6));
+ bus_space_write_4(sc->sc_iot, sc->sc_ioh, UART_FBRD,
+ UART_FBRD_DIVFRAC(div));
+ /* Commit baud rate change. */
+ bus_space_write_4(sc->sc_iot, sc->sc_ioh, UART_LCR_H, lcr);
+ /* Enable UART. */
+ bus_space_write_4(sc->sc_iot, sc->sc_ioh,
+ UART_CR, UART_CR_UARTEN | UART_CR_TXE | UART_CR_RXE);
}
/* setup fifo */
@@ -594,13 +629,6 @@ pluartopen(dev_t dev, int flag, int mode, struct proc *p)
5 << IMXUART_FCR_RFDIV_SH |
1 << IMXUART_FCR_RXTL_SH);
- bus_space_write_4(iot, ioh, IMXUART_UBIR,
- (pluartdefaultrate / 100) - 1);
-
- /* formula: clk / (rfdiv * 1600) */
- bus_space_write_4(iot, ioh, IMXUART_UBMR,
- (clk_get_rate(sc->sc_clk) * 1000) / 1600);
-
SET(sc->sc_ucr1, IMXUART_CR1_EN|IMXUART_CR1_RRDYEN);
SET(sc->sc_ucr2, IMXUART_CR2_TXEN|IMXUART_CR2_RXEN);
bus_space_write_4(iot, ioh, IMXUART_UCR1, sc->sc_ucr1);
diff --git sys/dev/ic/pluartvar.h sys/dev/ic/pluartvar.h
index 492c2a60b2c..47c64b9cc88 100644
--- sys/dev/ic/pluartvar.h
+++ sys/dev/ic/pluartvar.h
@@ -48,6 +48,7 @@ struct pluart_softc {
#define COM_SW_PPS 0x10
int sc_fifolen;
int sc_imsc;
+ int sc_clkfreq;
u_int8_t sc_initialize;
u_int8_t sc_cua;
