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.
Finally, good luck to you.
Signed-off-by: Wei Gang <gang.wei@intel.com>
diff -r 0475c567c708 xen/drivers/char/ns16550.c
--- a/xen/drivers/char/ns16550.c Tue Mar 23 09:37:59 2010 +0000
+++ b/xen/drivers/char/ns16550.c Wed Mar 24 17:03:58 2010 +0800
@@ -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
@@ -40,6 +40,11 @@ static struct ns16550 {
struct timer timer;
unsigned int timeout_ms;
int probing, intr_works;
+ /* on pci card */
+ unsigned int pb_bdf[3]; /* pci bridge BDF */
+ unsigned int ps_bdf[3]; /* pci serial port BDF */
+ int pb_bdf_enable:1; /* if =1, pb-bdf effective, port behind bridge */
+ int ps_bdf_enable:1; /* 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]);
+ }
+ }
}
}
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xensource.com
http://lists.xensource.com/xen-devel