[no subject]

From: Thomas Bogendoerfer
Date: Sat Nov 24 2007 - 21:10:41 EST

Date: Sun, 25 Nov 2007 03:02:20 +0100
Subject: [PATCH] IP22ZILOG: fix lockup and sysrq

- fix lockup when switching from early console to real console
- make sysrq reliable
- fix panic, if sysrq is issued before console is opened

Signed-off-by: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
---
arch/mips/sgi-ip22/ip22-setup.c | 19 ---
drivers/serial/ip22zilog.c | 247 +++++++++++++++++----------------------
include/linux/serial_core.h | 2 +-
3 files changed, 107 insertions(+), 161 deletions(-)

diff --git a/arch/mips/sgi-ip22/ip22-setup.c b/arch/mips/sgi-ip22/ip22-setup.c
index 174f09e..5f389ee 100644
--- a/arch/mips/sgi-ip22/ip22-setup.c
+++ b/arch/mips/sgi-ip22/ip22-setup.c
@@ -31,25 +31,6 @@
unsigned long sgi_gfxaddr;
EXPORT_SYMBOL_GPL(sgi_gfxaddr);

-/*
- * Stop-A is originally a Sun thing that isn't standard on IP22 so to avoid
- * accidents it's disabled by default on IP22.
- *
- * FIXME: provide a mechanism to change the value of stop_a_enabled.
- */
-int stop_a_enabled;
-
-void ip22_do_break(void)
-{
- if (!stop_a_enabled)
- return;
-
- printk("\n");
- ArcEnterInteractiveMode();
-}
-
-EXPORT_SYMBOL(ip22_do_break);
-
extern void ip22_be_init(void) __init;

void __init plat_mem_setup(void)
diff --git a/drivers/serial/ip22zilog.c b/drivers/serial/ip22zilog.c
index f3257f7..9c95bc0 100644
--- a/drivers/serial/ip22zilog.c
+++ b/drivers/serial/ip22zilog.c
@@ -45,8 +45,6 @@

#include "ip22zilog.h"

-void ip22_do_break(void);
-
/*
* On IP22 we need to delay after register accesses but we do not need to
* flush writes.
@@ -81,12 +79,9 @@ struct uart_ip22zilog_port {
#define IP22ZILOG_FLAG_REGS_HELD 0x00000040
#define IP22ZILOG_FLAG_TX_STOPPED 0x00000080
#define IP22ZILOG_FLAG_TX_ACTIVE 0x00000100
+#define IP22ZILOG_FLAG_RESET_DONE 0x00000200

- unsigned int cflag;
-
- /* L1-A keyboard break state. */
- int kbd_id;
- int l1_down;
+ unsigned int tty_break;

unsigned char parity_mask;
unsigned char prev_status;
@@ -250,13 +245,26 @@ static void ip22zilog_maybe_update_regs(struct uart_ip22zilog_port *up,
}
}

-static void ip22zilog_receive_chars(struct uart_ip22zilog_port *up,
- struct zilog_channel *channel)
+#define Rx_BRK 0x0100 /* BREAK event software flag. */
+#define Rx_SYS 0x0200 /* SysRq event software flag. */
+
+static struct tty_struct *ip22zilog_receive_chars(struct uart_ip22zilog_port *up,
+ struct zilog_channel *channel)
{
- struct tty_struct *tty = up->port.info->tty; /* XXX info==NULL? */
+ struct tty_struct *tty;
+ unsigned char ch, flag;
+ unsigned int r1;
+
+ tty = NULL;
+ if (up->port.info != NULL &&
+ up->port.info->tty != NULL)
+ tty = up->port.info->tty;

- while (1) {
- unsigned char ch, r1, flag;
+ for (;;) {
+ ch = readb(&channel->control);
+ ZSDELAY();
+ if (!(ch & Rx_CH_AV))
+ break;

r1 = read_zsreg(channel, R1);
if (r1 & (PAR_ERR | Rx_OVR | CRC_ERR)) {
@@ -265,43 +273,26 @@ static void ip22zilog_receive_chars(struct uart_ip22zilog_port *up,
ZS_WSYNC(channel);
}

- ch = readb(&channel->control);
- ZSDELAY();
-
- /* This funny hack depends upon BRK_ABRT not interfering
- * with the other bits we care about in R1.
- */
- if (ch & BRK_ABRT)
- r1 |= BRK_ABRT;
-
ch = readb(&channel->data);
ZSDELAY();

ch &= up->parity_mask;

- if (ZS_IS_CONS(up) && (r1 & BRK_ABRT)) {
- /* Wait for BREAK to deassert to avoid potentially
- * confusing the PROM.
- */
- while (1) {
- ch = readb(&channel->control);
- ZSDELAY();
- if (!(ch & BRK_ABRT))
- break;
- }
- ip22_do_break();
- return;
- }
+ /* Handle the null char got when BREAK is removed. */
+ if (!ch)
+ r1 |= up->tty_break;

/* A real serial line, record the character and status. */
flag = TTY_NORMAL;
up->port.icount.rx++;
- if (r1 & (BRK_ABRT | PAR_ERR | Rx_OVR | CRC_ERR)) {
- if (r1 & BRK_ABRT) {
- r1 &= ~(PAR_ERR | CRC_ERR);
+ if (r1 & (PAR_ERR | Rx_OVR | CRC_ERR | Rx_SYS | Rx_BRK)) {
+ up->tty_break = 0;
+
+ if (r1 & (Rx_SYS | Rx_BRK)) {
up->port.icount.brk++;
- if (uart_handle_break(&up->port))
- goto next_char;
+ if (r1 & Rx_SYS)
+ continue;
+ r1 &= ~(PAR_ERR | CRC_ERR);
}
else if (r1 & PAR_ERR)
up->port.icount.parity++;
@@ -310,30 +301,21 @@ static void ip22zilog_receive_chars(struct uart_ip22zilog_port *up,
if (r1 & Rx_OVR)
up->port.icount.overrun++;
r1 &= up->port.read_status_mask;
- if (r1 & BRK_ABRT)
+ if (r1 & Rx_BRK)
flag = TTY_BREAK;
else if (r1 & PAR_ERR)
flag = TTY_PARITY;
else if (r1 & CRC_ERR)
flag = TTY_FRAME;
}
- if (uart_handle_sysrq_char(&up->port, ch))
- goto next_char;

- if (up->port.ignore_status_mask == 0xff ||
- (r1 & up->port.ignore_status_mask) == 0)
- tty_insert_flip_char(tty, ch, flag);
+ if (uart_handle_sysrq_char(&up->port, ch))
+ continue;

- if (r1 & Rx_OVR)
- tty_insert_flip_char(tty, 0, TTY_OVERRUN);
- next_char:
- ch = readb(&channel->control);
- ZSDELAY();
- if (!(ch & Rx_CH_AV))
- break;
+ if (tty)
+ uart_insert_char(&up->port, r1, Rx_OVR, ch, flag);
}
-
- tty_flip_buffer_push(tty);
+ return tty;
}

static void ip22zilog_status_handle(struct uart_ip22zilog_port *up,
@@ -348,6 +330,15 @@ static void ip22zilog_status_handle(struct uart_ip22zilog_port *up,
ZSDELAY();
ZS_WSYNC(channel);

+ if (up->curregs[R15] & BRKIE) {
+ if ((status & BRK_ABRT) && !(up->prev_status & BRK_ABRT)) {
+ if (uart_handle_break(&up->port))
+ up->tty_break = Rx_SYS;
+ else
+ up->tty_break = Rx_BRK;
+ }
+ }
+
if (ZS_WANTS_MODEM_STATUS(up)) {
if (status & SYNC)
up->port.icount.dsr++;
@@ -356,10 +347,10 @@ static void ip22zilog_status_handle(struct uart_ip22zilog_port *up,
* But it does not tell us which bit has changed, we have to keep
* track of this ourselves.
*/
- if ((status & DCD) ^ up->prev_status)
+ if ((status ^ up->prev_status) ^ DCD)
uart_handle_dcd_change(&up->port,
(status & DCD));
- if ((status & CTS) ^ up->prev_status)
+ if ((status ^ up->prev_status) ^ CTS)
uart_handle_cts_change(&up->port,
(status & CTS));

@@ -447,19 +438,21 @@ static irqreturn_t ip22zilog_interrupt(int irq, void *dev_id)
while (up) {
struct zilog_channel *channel
= ZILOG_CHANNEL_FROM_PORT(&up->port);
+ struct tty_struct *tty;
unsigned char r3;

spin_lock(&up->port.lock);
r3 = read_zsreg(channel, R3);

/* Channel A */
+ tty = NULL;
if (r3 & (CHAEXT | CHATxIP | CHARxIP)) {
writeb(RES_H_IUS, &channel->control);
ZSDELAY();
ZS_WSYNC(channel);

if (r3 & CHARxIP)
- ip22zilog_receive_chars(up, channel);
+ tty = ip22zilog_receive_chars(up, channel);
if (r3 & CHAEXT)
ip22zilog_status_handle(up, channel);
if (r3 & CHATxIP)
@@ -467,18 +460,22 @@ static irqreturn_t ip22zilog_interrupt(int irq, void *dev_id)
}
spin_unlock(&up->port.lock);

+ if (tty)
+ tty_flip_buffer_push(tty);
+
/* Channel B */
up = up->next;
channel = ZILOG_CHANNEL_FROM_PORT(&up->port);

spin_lock(&up->port.lock);
+ tty = NULL;
if (r3 & (CHBEXT | CHBTxIP | CHBRxIP)) {
writeb(RES_H_IUS, &channel->control);
ZSDELAY();
ZS_WSYNC(channel);

if (r3 & CHBRxIP)
- ip22zilog_receive_chars(up, channel);
+ tty = ip22zilog_receive_chars(up, channel);
if (r3 & CHBEXT)
ip22zilog_status_handle(up, channel);
if (r3 & CHBTxIP)
@@ -486,6 +483,9 @@ static irqreturn_t ip22zilog_interrupt(int irq, void *dev_id)
}
spin_unlock(&up->port.lock);

+ if (tty)
+ tty_flip_buffer_push(tty);
+
up = up->next;
}

@@ -681,11 +681,46 @@ static void ip22zilog_break_ctl(struct uart_port *port, int break_state)
spin_unlock_irqrestore(&port->lock, flags);
}

+static void __ip22zilog_reset(struct uart_ip22zilog_port *up)
+{
+ struct zilog_channel *channel;
+ int i;
+
+ if (up->flags & IP22ZILOG_FLAG_RESET_DONE)
+ return;
+
+ /* Let pending transmits finish. */
+ channel = ZILOG_CHANNEL_FROM_PORT(&up->port);
+ for (i = 0; i < 1000; i++) {
+ unsigned char stat = read_zsreg(channel, R1);
+ if (stat & ALL_SNT)
+ break;
+ udelay(100);
+ }
+
+ if (!ZS_IS_CHANNEL_A(up)) {
+ up++;
+ channel = ZILOG_CHANNEL_FROM_PORT(&up->port);
+ }
+ write_zsreg(channel, R9, FHWRES);
+ ZSDELAY_LONG();
+ (void) read_zsreg(channel, R0);
+
+ up->flags |= IP22ZILOG_FLAG_RESET_DONE;
+ up->next->flags |= IP22ZILOG_FLAG_RESET_DONE;
+}
+
static void __ip22zilog_startup(struct uart_ip22zilog_port *up)
{
struct zilog_channel *channel;

channel = ZILOG_CHANNEL_FROM_PORT(&up->port);
+
+ __ip22zilog_reset(up);
+
+ __load_zsregs(channel, up->curregs);
+ /* set master interrupt enable */
+ write_zsreg(channel, R9, up->curregs[R9]);
up->prev_status = readb(&channel->control);

/* Enable receiver and transmitter. */
@@ -859,8 +894,6 @@ ip22zilog_set_termios(struct uart_port *port, struct ktermios *termios,
else
up->flags &= ~IP22ZILOG_FLAG_MODEM_STATUS;

- up->cflag = termios->c_cflag;
-
ip22zilog_maybe_update_regs(up, ZILOG_CHANNEL_FROM_PORT(port));
uart_update_timeout(port, termios->c_cflag, baud);

@@ -992,74 +1025,29 @@ ip22zilog_console_write(struct console *con, const char *s, unsigned int count)
spin_unlock_irqrestore(&up->port.lock, flags);
}

-void
-ip22serial_console_termios(struct console *con, char *options)
-{
- int baud = 9600, bits = 8, cflag;
- int parity = 'n';
- int flow = 'n';
-
- if (options)
- uart_parse_options(options, &baud, &parity, &bits, &flow);
-
- cflag = CREAD | HUPCL | CLOCAL;
-
- switch (baud) {
- case 150: cflag |= B150; break;
- case 300: cflag |= B300; break;
- case 600: cflag |= B600; break;
- case 1200: cflag |= B1200; break;
- case 2400: cflag |= B2400; break;
- case 4800: cflag |= B4800; break;
- case 9600: cflag |= B9600; break;
- case 19200: cflag |= B19200; break;
- case 38400: cflag |= B38400; break;
- default: baud = 9600; cflag |= B9600; break;
- }
-
- con->cflag = cflag | CS8; /* 8N1 */
-
- uart_update_timeout(&ip22zilog_port_table[con->index].port, cflag, baud);
-}
-
static int __init ip22zilog_console_setup(struct console *con, char *options)
{
struct uart_ip22zilog_port *up = &ip22zilog_port_table[con->index];
unsigned long flags;
- int baud, brg;
-
- printk("Console: ttyS%d (IP22-Zilog)\n", con->index);
+ int baud = 9600, bits = 8;
+ int parity = 'n';
+ int flow = 'n';

- /* Get firmware console settings. */
- ip22serial_console_termios(con, options);
+ up->flags |= IP22ZILOG_FLAG_IS_CONS;

- /* Firmware console speed is limited to 150-->38400 baud so
- * this hackish cflag thing is OK.
- */
- switch (con->cflag & CBAUD) {
- case B150: baud = 150; break;
- case B300: baud = 300; break;
- case B600: baud = 600; break;
- case B1200: baud = 1200; break;
- case B2400: baud = 2400; break;
- case B4800: baud = 4800; break;
- default: case B9600: baud = 9600; break;
- case B19200: baud = 19200; break;
- case B38400: baud = 38400; break;
- };
-
- brg = BPS_TO_BRG(baud, ZS_CLOCK / ZS_CLOCK_DIVISOR);
+ printk(KERN_INFO "Console: ttyS%d (IP22-Zilog)\n", con->index);

spin_lock_irqsave(&up->port.lock, flags);

- up->curregs[R15] = BRKIE;
- ip22zilog_convert_to_zs(up, con->cflag, 0, brg);
+ up->curregs[R15] |= BRKIE;

__ip22zilog_startup(up);

spin_unlock_irqrestore(&up->port.lock, flags);

- return 0;
+ if (options)
+ uart_parse_options(options, &baud, &parity, &bits, &flow);
+ return uart_set_options(&up->port, con, baud, parity, bits, flow);
}

static struct uart_driver ip22zilog_reg;
@@ -1140,25 +1128,10 @@ static void __init ip22zilog_prepare(void)
up[(chip * 2) + 1].port.line = (chip * 2) + 1;
up[(chip * 2) + 1].flags |= IP22ZILOG_FLAG_IS_CHANNEL_A;
}
-}
-
-static void __init ip22zilog_init_hw(void)
-{
- int i;
-
- for (i = 0; i < NUM_CHANNELS; i++) {
- struct uart_ip22zilog_port *up = &ip22zilog_port_table[i];
- struct zilog_channel *channel = ZILOG_CHANNEL_FROM_PORT(&up->port);
- unsigned long flags;
- int baud, brg;

- spin_lock_irqsave(&up->port.lock, flags);
-
- if (ZS_IS_CHANNEL_A(up)) {
- write_zsreg(channel, R9, FHWRES);
- ZSDELAY_LONG();
- (void) read_zsreg(channel, R0);
- }
+ for (channel = 0; channel < NUM_CHANNELS; channel++) {
+ struct uart_ip22zilog_port *up = &ip22zilog_port_table[channel];
+ int brg;

/* Normal serial TTY. */
up->parity_mask = 0xff;
@@ -1169,16 +1142,10 @@ static void __init ip22zilog_init_hw(void)
up->curregs[R9] = NV | MIE;
up->curregs[R10] = NRZ;
up->curregs[R11] = TCBR | RCBR;
- baud = 9600;
- brg = BPS_TO_BRG(baud, ZS_CLOCK / ZS_CLOCK_DIVISOR);
+ brg = BPS_TO_BRG(9600, ZS_CLOCK / ZS_CLOCK_DIVISOR);
up->curregs[R12] = (brg & 0xff);
up->curregs[R13] = (brg >> 8) & 0xff;
up->curregs[R14] = BRENAB;
- __load_zsregs(channel, up->curregs);
- /* set master interrupt enable */
- write_zsreg(channel, R9, up->curregs[R9]);
-
- spin_unlock_irqrestore(&up->port.lock, flags);
}
}

@@ -1195,8 +1162,6 @@ static int __init ip22zilog_ports_init(void)
panic("IP22-Zilog: Unable to register zs interrupt handler.\n");
}

- ip22zilog_init_hw();
-
ret = uart_register_driver(&ip22zilog_reg);
if (ret == 0) {
int i;
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 6a5203f..9963f81 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -437,7 +437,7 @@ uart_handle_sysrq_char(struct uart_port *port, unsigned int ch)
#ifdef SUPPORT_SYSRQ
if (port->sysrq) {
if (ch && time_before(jiffies, port->sysrq)) {
- handle_sysrq(ch, port->info->tty);
+ handle_sysrq(ch, port->info ? port->info->tty : NULL);
port->sysrq = 0;
return 1;
}
--
1.4.4.4

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