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-rw-r--r--drivers/serial/8250.c85
-rw-r--r--include/linux/serial_reg.h1
2 files changed, 57 insertions, 29 deletions
diff --git a/drivers/serial/8250.c b/drivers/serial/8250.c
index 301313002f6b..f94109cbb46e 100644
--- a/drivers/serial/8250.c
+++ b/drivers/serial/8250.c
@@ -129,7 +129,16 @@ struct uart_8250_port {
unsigned char mcr;
unsigned char mcr_mask; /* mask of user bits */
unsigned char mcr_force; /* mask of forced bits */
- unsigned char lsr_break_flag;
+
+ /*
+ * Some bits in registers are cleared on a read, so they must
+ * be saved whenever the register is read but the bits will not
+ * be immediately processed.
+ */
+#define LSR_SAVE_FLAGS UART_LSR_BRK_ERROR_BITS
+ unsigned char lsr_saved_flags;
+#define MSR_SAVE_FLAGS UART_MSR_ANY_DELTA
+ unsigned char msr_saved_flags;
/*
* We provide a per-port pm hook.
@@ -1238,6 +1247,7 @@ static void serial8250_start_tx(struct uart_port *port)
if (up->bugs & UART_BUG_TXEN) {
unsigned char lsr, iir;
lsr = serial_in(up, UART_LSR);
+ up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
iir = serial_in(up, UART_IIR) & 0x0f;
if ((up->port.type == PORT_RM9000) ?
(lsr & UART_LSR_THRE &&
@@ -1290,18 +1300,10 @@ receive_chars(struct uart_8250_port *up, unsigned int *status)
flag = TTY_NORMAL;
up->port.icount.rx++;
-#ifdef CONFIG_SERIAL_8250_CONSOLE
- /*
- * Recover the break flag from console xmit
- */
- if (up->port.line == up->port.cons->index) {
- lsr |= up->lsr_break_flag;
- up->lsr_break_flag = 0;
- }
-#endif
+ lsr |= up->lsr_saved_flags;
+ up->lsr_saved_flags = 0;
- if (unlikely(lsr & (UART_LSR_BI | UART_LSR_PE |
- UART_LSR_FE | UART_LSR_OE))) {
+ if (unlikely(lsr & UART_LSR_BRK_ERROR_BITS)) {
/*
* For statistics only
*/
@@ -1392,6 +1394,8 @@ static unsigned int check_modem_status(struct uart_8250_port *up)
{
unsigned int status = serial_in(up, UART_MSR);
+ status |= up->msr_saved_flags;
+ up->msr_saved_flags = 0;
if (status & UART_MSR_ANY_DELTA && up->ier & UART_IER_MSI &&
up->port.info != NULL) {
if (status & UART_MSR_TERI)
@@ -1591,7 +1595,8 @@ static void serial8250_timeout(unsigned long data)
static void serial8250_backup_timeout(unsigned long data)
{
struct uart_8250_port *up = (struct uart_8250_port *)data;
- unsigned int iir, ier = 0;
+ unsigned int iir, ier = 0, lsr;
+ unsigned long flags;
/*
* Must disable interrupts or else we risk racing with the interrupt
@@ -1610,9 +1615,13 @@ static void serial8250_backup_timeout(unsigned long data)
* the "Diva" UART used on the management processor on many HP
* ia64 and parisc boxes.
*/
+ spin_lock_irqsave(&up->port.lock, flags);
+ lsr = serial_in(up, UART_LSR);
+ up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
+ spin_unlock_irqrestore(&up->port.lock, flags);
if ((iir & UART_IIR_NO_INT) && (up->ier & UART_IER_THRI) &&
(!uart_circ_empty(&up->port.info->xmit) || up->port.x_char) &&
- (serial_in(up, UART_LSR) & UART_LSR_THRE)) {
+ (lsr & UART_LSR_THRE)) {
iir &= ~(UART_IIR_ID | UART_IIR_NO_INT);
iir |= UART_IIR_THRI;
}
@@ -1631,13 +1640,14 @@ static unsigned int serial8250_tx_empty(struct uart_port *port)
{
struct uart_8250_port *up = (struct uart_8250_port *)port;
unsigned long flags;
- unsigned int ret;
+ unsigned int lsr;
spin_lock_irqsave(&up->port.lock, flags);
- ret = serial_in(up, UART_LSR) & UART_LSR_TEMT ? TIOCSER_TEMT : 0;
+ lsr = serial_in(up, UART_LSR);
+ up->lsr_saved_flags |= lsr & LSR_SAVE_FLAGS;
spin_unlock_irqrestore(&up->port.lock, flags);
- return ret;
+ return lsr & UART_LSR_TEMT ? TIOCSER_TEMT : 0;
}
static unsigned int serial8250_get_mctrl(struct uart_port *port)
@@ -1708,8 +1718,7 @@ static inline void wait_for_xmitr(struct uart_8250_port *up, int bits)
do {
status = serial_in(up, UART_LSR);
- if (status & UART_LSR_BI)
- up->lsr_break_flag = UART_LSR_BI;
+ up->lsr_saved_flags |= status & LSR_SAVE_FLAGS;
if (--tmout == 0)
break;
@@ -1718,8 +1727,12 @@ static inline void wait_for_xmitr(struct uart_8250_port *up, int bits)
/* Wait up to 1s for flow control if necessary */
if (up->port.flags & UPF_CONS_FLOW) {
- tmout = 1000000;
- while (!(serial_in(up, UART_MSR) & UART_MSR_CTS) && --tmout) {
+ unsigned int tmout;
+ for (tmout = 1000000; tmout; tmout--) {
+ unsigned int msr = serial_in(up, UART_MSR);
+ up->msr_saved_flags |= msr & MSR_SAVE_FLAGS;
+ if (msr & UART_MSR_CTS)
+ break;
udelay(1);
touch_nmi_watchdog();
}
@@ -1889,6 +1902,18 @@ static int serial8250_startup(struct uart_port *port)
spin_unlock_irqrestore(&up->port.lock, flags);
/*
+ * Clear the interrupt registers again for luck, and clear the
+ * saved flags to avoid getting false values from polling
+ * routines or the previous session.
+ */
+ serial_inp(up, UART_LSR);
+ serial_inp(up, UART_RX);
+ serial_inp(up, UART_IIR);
+ serial_inp(up, UART_MSR);
+ up->lsr_saved_flags = 0;
+ up->msr_saved_flags = 0;
+
+ /*
* Finally, enable interrupts. Note: Modem status interrupts
* are set via set_termios(), which will be occurring imminently
* anyway, so we don't enable them here.
@@ -1906,14 +1931,6 @@ static int serial8250_startup(struct uart_port *port)
(void) inb_p(icp);
}
- /*
- * And clear the interrupt registers again for luck.
- */
- (void) serial_inp(up, UART_LSR);
- (void) serial_inp(up, UART_RX);
- (void) serial_inp(up, UART_IIR);
- (void) serial_inp(up, UART_MSR);
-
return 0;
}
@@ -2484,6 +2501,16 @@ serial8250_console_write(struct console *co, const char *s, unsigned int count)
wait_for_xmitr(up, BOTH_EMPTY);
serial_out(up, UART_IER, ier);
+ /*
+ * The receive handling will happen properly because the
+ * receive ready bit will still be set; it is not cleared
+ * on read. However, modem control will not, we must
+ * call it if we have saved something in the saved flags
+ * while processing with interrupts off.
+ */
+ if (up->msr_saved_flags)
+ check_modem_status(up);
+
if (locked)
spin_unlock(&up->port.lock);
local_irq_restore(flags);
diff --git a/include/linux/serial_reg.h b/include/linux/serial_reg.h
index 1c5ed7d92b0f..96c0d93fc2ca 100644
--- a/include/linux/serial_reg.h
+++ b/include/linux/serial_reg.h
@@ -118,6 +118,7 @@
#define UART_LSR_PE 0x04 /* Parity error indicator */
#define UART_LSR_OE 0x02 /* Overrun error indicator */
#define UART_LSR_DR 0x01 /* Receiver data ready */
+#define UART_LSR_BRK_ERROR_BITS 0x1E /* BI, FE, PE, OE bits */
#define UART_MSR 6 /* In: Modem Status Register */
#define UART_MSR_DCD 0x80 /* Data Carrier Detect */
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-15 00:58:04 +0000