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SubjectPCI Express support for 2.4 kernel
Please, ignore previous submission with the same subject. Patch file 
attached was wrong one. Now correct patch attached.

Hi,
PCI-Express platforms will soon appear on the market. It is worth to
support it.

Following is patch for 2.4.23 kernel. I tested it on my host, it works
properly.
I did it for i386 only, I have no other architecture to test.

It was patch on the same subject from* Seshadri, Harinarayanan*
(/harinarayanan.seshadri@intel.com/
<mailto:harinarayanan.seshadri@intel.com>)
http://www.cs.helsinki.fi/linux/linux-kernel/2003-17/0247.html
My version differ in several aspects: it is for 2.4 (vs. 2.6); it do not
ioremap/unmap page for each transaction.

How about inclusion in 2.4.24?

I am not subscribed to lkml, thus please CC me
(Vladimir Kondratiev <vladimir.kondratiev@intel.com>) in replies.

Vladimir.

Enable PCI Express access method for configuration space
This path includes:
* access routines itself
* command line argument "pci=exp" to force PCI Express, similar to "conf1" and "conf2"
* full 4k config accessed through /proc/bus/pci/...

How it works:

With PCI-E, config space accessed through memory. Each device gets its own 4k memory mapped config,
total 256M for all devices.

At init time, I map whole region to not spent time for mapping later.

For /proc/bus/pci/..., I changed PCI_CFG_SPACE_SIZE to variable and changed it to 4k for PCI-E.

It is tested on 1 platform.

Author: "Vladimir Kondratiev" <vladimir.kondratiev@intel.com>
diff -bBdur linux-2.4.23/arch/i386/kernel/pci-i386.h linux-2.4.23-pciexp/arch/i386/kernel/pci-i386.h
--- linux-2.4.23/arch/i386/kernel/pci-i386.h 2003-11-28 20:26:19.000000000 +0200
+++ linux-2.4.23-pciexp/arch/i386/kernel/pci-i386.h 2003-12-14 11:08:17.000000000 +0200
@@ -15,6 +15,7 @@
#define PCI_PROBE_BIOS 0x0001
#define PCI_PROBE_CONF1 0x0002
#define PCI_PROBE_CONF2 0x0004
+#define PCI_PROBE_EXP 0x0008
#define PCI_NO_SORT 0x0100
#define PCI_BIOS_SORT 0x0200
#define PCI_NO_CHECKS 0x0400
diff -bBdur linux-2.4.23/arch/i386/kernel/pci-pc.c linux-2.4.23-pciexp/arch/i386/kernel/pci-pc.c
--- linux-2.4.23/arch/i386/kernel/pci-pc.c 2003-11-28 20:26:19.000000000 +0200
+++ linux-2.4.23-pciexp/arch/i386/kernel/pci-pc.c 2003-12-14 21:27:52.000000000 +0200
@@ -20,7 +20,7 @@

#include "pci-i386.h"

-unsigned int pci_probe = PCI_PROBE_BIOS | PCI_PROBE_CONF1 | PCI_PROBE_CONF2;
+unsigned int pci_probe = PCI_PROBE_BIOS | PCI_PROBE_CONF1 | PCI_PROBE_CONF2 | PCI_PROBE_EXP;

int pcibios_last_bus = -1;
struct pci_bus *pci_root_bus = NULL;
@@ -427,6 +427,155 @@
pci_conf2_write_config_dword
};

+/**
+ * PCI Express routines
+ * "Vladimir Kondratiev" <vladimir.kondratiev@intel.com>
+ */
+/**
+ * RRBAR (memory base for PCI-E config space) resides here.
+ * Initialized to default address. Actually, it is platform specific, and
+ * value may vary.
+ * I don't know how to detect it properly, it is chipset specific.
+ */
+static u32 rrbar_phys=0xe0000000UL;
+/**
+ * RRBAR is always 256M
+ */
+static u32 rrbar_size=0x10000000UL;
+/**
+ * Virtual address for RRBAR
+ */
+static void* rrbar_virt=NULL;
+/**
+ * It used to be #define, but I am going to change it.
+ */
+extern int PCI_CFG_SPACE_SIZE;
+
+/**
+ * Initializes PCI Express method for config space access.
+ *
+ * There is no standard method to recognize presence of PCI Express,
+ * thus we will assume it is PCI-E, and rely on sanity check to
+ * deassert PCI-E presense. If PCI-E not present,
+ * there is no physical RAM on RRBAR address, and we should read
+ * something like 0xff.
+ *
+ * Creates mapping for whole 256M area.
+ *
+ * @return 1 if OK, 0 if error
+ */
+static int pci_express_init(void)
+{
+ /* TODO: check PCI-Ex presense */
+ rrbar_virt=ioremap(rrbar_phys,rrbar_size);
+ if (!rrbar_virt) return 0;
+ return 1;
+}
+
+/**
+ * Shuts down PCI-E resources.
+ */
+static void pci_express_fini(void)
+{
+ if (rrbar_virt) {
+ iounmap(rrbar_virt);
+ }
+}
+
+static int pci_exp_read (int seg, int bus, int dev, int fn, int reg, int len, u32 *value)
+{
+ void* addr=rrbar_virt+(bus << 20)+(dev << 15)+(fn << 12)+reg;
+ if ((bus > 255 || dev > 31 || fn > 7 || reg > 4095))
+ return -EINVAL;
+ switch (len) {
+ case 1:
+ *value=readb(addr);
+ break;
+ case 2:
+ if (reg&1) return -EINVAL;
+ *value=readw(addr);
+ break;
+ case 4:
+ if (reg&3) return -EINVAL;
+ *value=readl(addr);
+ break;
+ }
+ return 0;
+}
+
+static int pci_exp_write (int seg, int bus, int dev, int fn, int reg, int len, u32 value)
+{
+ void* addr=rrbar_virt+(bus << 20)+(dev << 15)+(fn << 12)+reg;
+ if ((bus > 255 || dev > 31 || fn > 7 || reg > 4095))
+ return -EINVAL;
+ switch (len) {
+ case 1:
+ writeb(value,addr);
+ break;
+ case 2:
+ if (reg&1) return -EINVAL;
+ writew(value,addr);
+ break;
+ case 4:
+ if (reg&3) return -EINVAL;
+ writel(value,addr);
+ break;
+ }
+ return 0;
+}
+
+static int pci_exp_read_config_byte(struct pci_dev *dev, int where, u8 *value)
+{
+ int result;
+ u32 data;
+ result = pci_exp_read(0, dev->bus->number, PCI_SLOT(dev->devfn),
+ PCI_FUNC(dev->devfn), where, 1, &data);
+ *value = (u8)data;
+ return result;
+}
+
+static int pci_exp_read_config_word(struct pci_dev *dev, int where, u16 *value)
+{
+ int result;
+ u32 data;
+ result = pci_exp_read(0, dev->bus->number, PCI_SLOT(dev->devfn),
+ PCI_FUNC(dev->devfn), where, 2, &data);
+ *value = (u16)data;
+ return result;
+}
+
+static int pci_exp_read_config_dword(struct pci_dev *dev, int where, u32 *value)
+{
+ return pci_exp_read(0, dev->bus->number, PCI_SLOT(dev->devfn),
+ PCI_FUNC(dev->devfn), where, 4, value);
+}
+
+static int pci_exp_write_config_byte(struct pci_dev *dev, int where, u8 value)
+{
+ return pci_exp_write(0, dev->bus->number, PCI_SLOT(dev->devfn),
+ PCI_FUNC(dev->devfn), where, 1, value);
+}
+
+static int pci_exp_write_config_word(struct pci_dev *dev, int where, u16 value)
+{
+ return pci_exp_write(0, dev->bus->number, PCI_SLOT(dev->devfn),
+ PCI_FUNC(dev->devfn), where, 2, value);
+}
+
+static int pci_exp_write_config_dword(struct pci_dev *dev, int where, u32 value)
+{
+ return pci_exp_write(0, dev->bus->number, PCI_SLOT(dev->devfn),
+ PCI_FUNC(dev->devfn), where, 4, value);
+}
+
+static struct pci_ops pci_express_conf = {
+ pci_exp_read_config_byte,
+ pci_exp_read_config_word,
+ pci_exp_read_config_dword,
+ pci_exp_write_config_byte,
+ pci_exp_write_config_word,
+ pci_exp_write_config_dword
+};

/*
* Before we decide to use direct hardware access mechanisms, we try to do some
@@ -465,6 +614,21 @@

__save_flags(flags); __cli();

+ /**
+ * Check if PCI-express access work
+ */
+ if (pci_express_init()) {
+ if (pci_sanity_check(&pci_express_conf)) {
+ PCI_CFG_SPACE_SIZE=4096;
+ __restore_flags(flags);
+ printk(KERN_INFO "PCI: Using configuration type PCI Express\n");
+ request_mem_region(rrbar_phys, rrbar_size, "PCI-Express config space");
+ return &pci_express_conf;
+ } else {
+ pci_express_fini();
+ }
+ }
+
/*
* Check if configuration type 1 works.
*/
@@ -1398,16 +1562,18 @@
#endif

#ifdef CONFIG_PCI_DIRECT
- if ((pci_probe & (PCI_PROBE_CONF1 | PCI_PROBE_CONF2))
+ if ((pci_probe & (PCI_PROBE_CONF1 | PCI_PROBE_CONF2 | PCI_PROBE_EXP))
&& (tmp = pci_check_direct())) {
pci_root_ops = tmp;
if (pci_root_ops == &pci_direct_conf1) {
pci_config_read = pci_conf1_read;
pci_config_write = pci_conf1_write;
- }
- else {
+ } else if (pci_root_ops == &pci_direct_conf2) {
pci_config_read = pci_conf2_read;
pci_config_write = pci_conf2_write;
+ } else if (pci_root_ops == &pci_express_conf) {
+ pci_config_read = pci_exp_read;
+ pci_config_write = pci_exp_write;
}
}
#endif
@@ -1489,6 +1655,10 @@
pci_probe = PCI_PROBE_CONF2 | PCI_NO_CHECKS;
return NULL;
}
+ else if (!strcmp(str, "exp")) {
+ pci_probe = PCI_PROBE_EXP | PCI_NO_CHECKS;
+ return NULL;
+ }
#endif
else if (!strcmp(str, "rom")) {
pci_probe |= PCI_ASSIGN_ROMS;
diff -bBdur linux-2.4.23/drivers/pci/proc.c linux-2.4.23-pciexp/drivers/pci/proc.c
--- linux-2.4.23/drivers/pci/proc.c 2002-11-29 01:53:14.000000000 +0200
+++ linux-2.4.23-pciexp/drivers/pci/proc.c 2003-12-14 14:18:58.000000000 +0200
@@ -16,7 +16,7 @@
#include <asm/uaccess.h>
#include <asm/byteorder.h>

-#define PCI_CFG_SPACE_SIZE 256
+int PCI_CFG_SPACE_SIZE=256;

static loff_t
proc_bus_pci_lseek(struct file *file, loff_t off, int whence)
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