Mailing List Archive

# HG changeset patch
# User Keir Fraser <keir.fraser@citrix.com>
# Date 1270026701 -3600
# Node ID 589d075ba2953123c1b39ecdbc190689ac6f443c
# Parent ebd84be3420a4453b3024d3378d8d84b81f44118
ns16550: enable PCI serial card usage

On some machine, there is no build-in serial port and no LPC
connection. To use serial port, we have to plug in a serial
card. Sometime BIOS doesn't enable the BARs for the PCI devices which
lead to that Xen can't use the add-in serial port for early log
print. This patch try to initialize the serial card and related PCI
bridge to make it usable for xen.

Usage:

Step 1. boot into bare metal Linux, get the information for the PCI
serial ports and the related PCI bridge. On my case:

#lspci -v
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev 90)
(prog-if 01 [Subtractive decode])
Bus: primary=00, secondary=06, subordinate=06, sec-latency=32
I/O behind bridge: 00005000-00005fff

06:02.0 Serial controller: Lava Computer mfg Inc Lava DSerial-PCI Port
A (prog-if 02 [16550])
Region 0: I/O ports at 5000 [size=8]

Step 2. revise the grub.conf to include
'com1=115200,8n1,0xPPPP,0,<port-bdf>,<bridge-bdf> console=com1' for
xen cmdline. The 0xPPPP is the base I/O port address got for the
serial port in bare metal Linux. For my case, it is 0x5000. The 0
after 0xPPPP means enable polling model for the serial port. The
<port-bdf> is the serial port BDF, 06:02.0 in my case; the
<bridge-bdf> is the bridge BDF bebind which the serial card locates,
00:1e.0 for my case.

Signed-off-by: Wei Gang <gang.wei@intel.com>
---
xen/drivers/char/ns16550.c | 53 +++++++++++++++++++++++++++++++++++++++++++--
1 files changed, 51 insertions(+), 2 deletions(-)

diff -r ebd84be3420a -r 589d075ba295 xen/drivers/char/ns16550.c
--- a/xen/drivers/char/ns16550.c Tue Mar 30 18:31:39 2010 +0100
+++ b/xen/drivers/char/ns16550.c Wed Mar 31 10:11:41 2010 +0100
@@ -19,7 +19,7 @@

/*
* Configure serial port with a string:
- * <baud>[/<clock_hz>][,DPS[,<io-base>[,<irq>]]].
+ * <baud>[/<clock_hz>][,DPS[,<io-base>[,<irq>[,<port-bdf>[,<bridge-bdf>]]]]].
* The tail of the string can be omitted if platform defaults are sufficient.
* If the baud rate is pre-configured, perhaps by a bootloader, then 'auto'
* can be specified in place of a numeric baud rate. Polled mode is specified
@@ -39,7 +39,12 @@ static struct ns16550 {
/* UART with no IRQ line: periodically-polled I/O. */
struct timer timer;
unsigned int timeout_ms;
- int probing, intr_works;
+ bool_t probing, intr_works;
+ /* PCI card parameters. */
+ unsigned int pb_bdf[3]; /* pci bridge BDF */
+ unsigned int ps_bdf[3]; /* pci serial port BDF */
+ bool_t pb_bdf_enable; /* if =1, pb-bdf effective, port behind bridge */
+ bool_t ps_bdf_enable; /* if =1, ps_bdf effective, port on pci card */
} ns16550_com[2] = { { 0 } };

/* Register offsets */
@@ -204,11 +209,28 @@ static int ns16550_getc(struct serial_po
return 1;
}

+static void pci_serial_early_init(struct ns16550 *uart)
+{
+ if ( !uart->ps_bdf_enable )
+ return;
+
+ if ( uart->pb_bdf_enable )
+ pci_conf_write16(uart->pb_bdf[0], uart->pb_bdf[1], uart->pb_bdf[2],
+ 0x1c, (uart->io_base & 0xF000) | ((uart->io_base & 0xF000) >> 8));
+
+ pci_conf_write32(uart->ps_bdf[0], uart->ps_bdf[1], uart->ps_bdf[2],
+ 0x10, uart->io_base | 0x1);
+ pci_conf_write16(uart->ps_bdf[0], uart->ps_bdf[1], uart->ps_bdf[2],
+ 0x4, 0x1);
+}
+
static void __devinit ns16550_init_preirq(struct serial_port *port)
{
struct ns16550 *uart = port->uart;
unsigned char lcr;
unsigned int divisor;
+
+ pci_serial_early_init(uart);

/* I/O ports are distinguished by their size (16 bits). */
if ( uart->io_base >= 0x10000 )
@@ -336,6 +358,19 @@ static int __init parse_parity_char(int
return 0;
}

+static void __init parse_pci_bdf(const char **conf, unsigned int bdf[3])
+{
+ bdf[0] = simple_strtoul(*conf, conf, 16);
+ if ( **conf != ':' )
+ return;
+ (*conf)++;
+ bdf[1] = simple_strtoul(*conf, conf, 16);
+ if ( **conf != '.' )
+ return;
+ (*conf)++;
+ bdf[2] = simple_strtoul(*conf, conf, 16);
+}
+
static int __init check_existence(struct ns16550 *uart)
{
unsigned char status, scratch, scratch2, scratch3;
@@ -347,6 +382,8 @@ static int __init check_existence(struct
if ( uart->io_base >= 0x10000 )
return 1;

+ pci_serial_early_init(uart);
+
/*
* Do a simple existence test first; if we fail this,
* there's no point trying anything else.
@@ -428,6 +465,18 @@ static void __init ns16550_parse_port_co
{
conf++;
uart->irq = simple_strtoul(conf, &conf, 10);
+ if ( *conf == ',' )
+ {
+ conf++;
+ uart->ps_bdf_enable = 1;
+ parse_pci_bdf(&conf, &uart->ps_bdf[0]);
+ if ( *conf == ',' )
+ {
+ conf++;
+ uart->pb_bdf_enable = 1;
+ parse_pci_bdf(&conf, &uart->pb_bdf[0]);
+ }
+ }
}
}


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