svn commit: r259753 - stable/9/sys/arm/at91

[Warner Losh]

Author: imp
Date: Sun Dec 22 23:33:27 2013
New Revision: 259753
URL: http://svnweb.freebsd.org/changeset/base/259753

Log:
  Direct Commit of mountroot> prompt fix r259748 (since there's no sane
  branching relationship between that branch and this one and since the
  more general fix in head may be too risky for a stbale branch this
  mature):
  
   Fix mountroot> prompt eating most of the characters by not enabling
   RXRDY interrupts in the attach routine. Instead, defer this until the
   first interrupt we see after the device is opened. Given the console
   use case, we're guaranteed to get a TXRDY interrupt before any reads
   are posted due to boot messages, which makes this work.
  
   The real fix is to use cngrab/cnungrab function pointers to disable
   RXRDY interrupts while grabbed. However, that touches the MI uart
   code, so was disallowed for 10.0 due to the lateness of the hour this
   fix was proposed. It works for mountroot, the most common atmel kernel
   prompt use cases, but wouldn't work for GELI since it prompts later in
   the boot process.

Modified:
  stable/9/sys/arm/at91/uart_dev_at91usart.c

Modified: stable/9/sys/arm/at91/uart_dev_at91usart.c
==============================================================================
--- stable/9/sys/arm/at91/uart_dev_at91usart.c	Sun Dec 22 23:31:04 2013	(r259752)
+++ stable/9/sys/arm/at91/uart_dev_at91usart.c	Sun Dec 22 23:33:27 2013	(r259753)
@@ -63,7 +63,8 @@ struct at91_usart_softc {
 	bus_dma_tag_t tx_tag;
 	bus_dmamap_t tx_map;
 	uint32_t flags;
-#define	HAS_TIMEOUT	1
+#define	HAS_TIMEOUT		0x1
+#define	NEEDS_RXRDY		0x4
 	bus_dma_tag_t rx_tag;
 	struct at91_usart_rx ping_pong[2];
 	struct at91_usart_rx *ping;
@@ -425,7 +426,13 @@ at91_usart_bus_attach(struct uart_softc 
 		WR4(&sc->sc_bas, USART_IER, USART_CSR_TIMEOUT |
 		    USART_CSR_RXBUFF | USART_CSR_ENDRX);
 	} else {
-		WR4(&sc->sc_bas, USART_IER, USART_CSR_RXRDY);
+		/*
+		 * Defer turning on the RXRDY bit until we're opened. This is to make the
+		 * mountroot prompt work before we've opened the console. This is a workaround
+		 * for not being able to change the UART interface for the 10.0 release.
+		 */
+		atsc->flags |= NEEDS_RXRDY;
+		/* WR4(&sc->sc_bas, USART_IER, USART_CSR_RXRDY); */
 	}
 	WR4(&sc->sc_bas, USART_IER, USART_CSR_RXBRK);
 errout:
@@ -530,6 +537,13 @@ at91_usart_bus_ipend(struct uart_softc *
 	ipend = 0;
 	atsc = (struct at91_usart_softc *)sc;
 	uart_lock(sc->sc_hwmtx);
+
+	/* Kludge -- Enable the RXRDY we deferred in attach */
+	if (sc->sc_opened && (atsc->flags & NEEDS_RXRDY)) {
+		WR4(&sc->sc_bas, USART_IER, USART_CSR_RXRDY);
+		atsc->flags &= ~NEEDS_RXRDY;
+	}
+
 	csr = RD4(&sc->sc_bas, USART_CSR);
 	if (csr & USART_CSR_ENDTX) {
 		bus_dmamap_sync(atsc->tx_tag, atsc->tx_map,