Martin,
We spoke a while back about a pcispeed= command line param to set the PCI
busspeed values (for later querying, if needed). Attached is my patch to
implement the feature we agreed upon. It is against linux-2.4.5.
Below is our previous discussion, as a refresher :). Please let me know if
this is not suitable for general inclusion in the kernel, and I'll try to
make it so.
Tim
(cc: lkml, alan)
Martin Mares wrote:
> > What do you think of my pcispeed=0:33,2:66 idea?
> anything -- the 33/66 MHz values from the PCI specs are only upper limits),
> I'll welcome this option, but otherwise I'd rather like to use the measuring
> code in IDE driver as it requires no user intervention to get the right
> timing.
--
Tim Hockin
Systems Software Engineer
Sun Microsystems, Cobalt Server Appliances
[EMAIL PROTECTED]
diff -ruN dist-2.4.5/drivers/pci/pci.c cobalt-2.4.5/drivers/pci/pci.c
--- dist-2.4.5/drivers/pci/pci.c Sat May 19 17:43:06 2001
+++ cobalt-2.4.5/drivers/pci/pci.c Thu May 31 14:32:33 2001
@@ -20,6 +20,7 @@
#include <linux/ioport.h>
#include <linux/spinlock.h>
#include <linux/pm.h>
+#include <linux/ctype.h>
#include <linux/kmod.h> /* for hotplug_path */
#include <linux/bitops.h>
@@ -37,6 +38,8 @@
LIST_HEAD(pci_root_buses);
LIST_HEAD(pci_devices);
+static int get_bus_speed(struct pci_bus *bus);
+
/**
* pci_find_slot - locate PCI device from a given PCI slot
* @bus: number of PCI bus on which desired PCI device resides
@@ -928,6 +931,7 @@
child->number = child->secondary = busnr;
child->primary = parent->secondary;
child->subordinate = 0xff;
+ child->bus_speed = get_bus_speed(child);
/* Set up default resource pointers.. */
for (i = 0; i < 4; i++)
@@ -1110,8 +1114,19 @@
return NULL;
/* some broken boards return 0 or ~0 if a slot is empty: */
- if (l == 0xffffffff || l == 0x00000000 || l == 0x0000ffff || l == 0xffff0000)
+ if (l == 0xffffffff || l == 0x00000000
+ || l == 0x0000ffff || l == 0xffff0000) {
+ /*
+ * host/pci and pci/pci bridges will set Received Master Abort
+ * (bit 13) on failed configuration access (happens when
+ * searching for devices). To be safe, clear the status
+ * register.
+ */
+ unsigned short st;
+ pci_read_config_word(temp, PCI_STATUS, &st);
+ pci_write_config_word(temp, PCI_STATUS, st);
return NULL;
+ }
dev = kmalloc(sizeof(*dev), GFP_KERNEL);
if (!dev)
@@ -1239,6 +1254,7 @@
list_add_tail(&b->node, &pci_root_buses);
b->number = b->secondary = bus;
+ b->bus_speed = get_bus_speed(b);
b->resource[0] = &ioport_resource;
b->resource[1] = &iomem_resource;
return b;
@@ -1739,7 +1755,66 @@
return 1;
}
+#define MAX_OVERRIDES 256
+static int pci_speed_overrides[MAX_OVERRIDES] __initdata;
+
+static int __init get_bus_speed(struct pci_bus *bus)
+{
+ if (!bus) {
+ return -1;
+ }
+
+ if (pci_speed_overrides[bus->number]) {
+ return pci_speed_overrides[bus->number];
+ } else {
+ /* printk("PCI: assuming 33 MHz for bus %d\n", bus->number); */
+ return 33;
+ }
+}
+
+/* handle pcispeed=0:33,1:66 parameter (speed=0 means unknown) */
+static int __init pci_speed_setup(char *str)
+{
+ while (str) {
+ char *k = strchr(str, ',');
+ if (k) {
+ *k++ = '\0';
+ }
+
+ if (*str) {
+ int bus;
+ int speed;
+ char *endp;
+
+ if (!isdigit(*str)) {
+ printk("PCI: bad bus number for "
+ "pcispeed parameter\n");
+ str = k;
+ continue;
+ }
+ bus = simple_strtoul(str, &endp, 0);
+
+ if (!*endp || !isdigit(*(++endp))) {
+ printk("PCI: bad speed for "
+ "pcispeed parameter\n");
+ str = k;
+ continue;
+ }
+ speed = simple_strtoul(endp, NULL, 0);
+ pci_speed_overrides[bus] = speed;
+ printk("PCI: setting bus %d speed to %d MHz\n",
+ bus, speed);
+
+ str = k;
+ } else {
+ break;
+ }
+ }
+ return 1;
+}
+
__setup("pci=", pci_setup);
+__setup("pcispeed=", pci_speed_setup);
EXPORT_SYMBOL(pci_read_config_byte);
diff -ruN dist-2.4.5/include/linux/pci.h cobalt-2.4.5/include/linux/pci.h
--- dist-2.4.5/include/linux/pci.h Fri May 25 18:02:11 2001
+++ cobalt-2.4.5/include/linux/pci.h Thu May 31 14:33:17 2001
@@ -1,5 +1,5 @@
/*
- * $Id: pci.h,v 1.87 1998/10/11 15:13:12 mj Exp $
+ * $Id: pci.h,v 1.1.1.3 2001/04/04 20:08:09 thockin Exp $
*
* PCI defines and function prototypes
* Copyright 1994, Drew Eckhardt
@@ -413,6 +413,7 @@
unsigned char primary; /* number of primary bridge */
unsigned char secondary; /* number of secondary bridge */
unsigned char subordinate; /* max number of subordinate buses */
+ int bus_speed; /* the speed of this PCI segment */
char name[48];
unsigned short vendor;
