m5a99x-evo: ugly quirks, but WOOT: ohai seabios :-)
[coreboot.git] / src / devices / hypertransport.c
index 411e7542c0680e82f341e82c886312f5e9a94b82..2a733867e6a38cbada563b1f57f25f52c478aeef 100644 (file)
@@ -1,3 +1,28 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * Copyright (C) 2003-2004 Linux Networx
+ * (Written by Eric Biederman <ebiederman@lnxi.com> for Linux Networx)
+ * Copyright (C) 2004 David Hendricks <sc@flagen.com>
+ * Copyright (C) 2004 Li-Ta Lo <ollie@lanl.gov>
+ * Copyright (C) 2005-2006 Tyan
+ * (Written by Yinghai Lu <yhlu@tyan.com> for Tyan)
+ * Copyright (C) 2005-2006 Stefan Reinauer <stepan@openbios.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
 #include <bitops.h>
 #include <console/console.h>
 #include <device/device.h>
 #include <device/pci.h>
 #include <device/pci_ids.h>
 #include <device/hypertransport.h>
-#include <part/hard_reset.h>
-#include <part/fallback_boot.h>
+
+/*
+ * The hypertransport link is already optimized in pre-RAM code so don't do
+ * it again.
+ */
+#define OPT_HT_LINK 0
+
+#if OPT_HT_LINK == 1
+#include <cpu/amd/model_fxx_rev.h>
+#endif
 
 static device_t ht_scan_get_devs(device_t *old_devices)
 {
        device_t first, last;
+
        first = *old_devices;
        last = first;
-       while(last && last->sibling && 
-               (last->sibling->path.type == DEVICE_PATH_PCI) &&
-               (last->sibling->path.u.pci.devfn > last->path.u.pci.devfn)) {
+
+       /*
+        * Extract the chain of devices to (first through last) for the next
+        * hypertransport device.
+        */
+       while (last && last->sibling &&
+              (last->sibling->path.type == DEVICE_PATH_PCI) &&
+              (last->sibling->path.pci.devfn > last->path.pci.devfn))
+       {
                last = last->sibling;
        }
+
        if (first) {
+               device_t child;
+
+               /* Unlink the chain from the list of old devices. */
                *old_devices = last->sibling;
                last->sibling = 0;
+
+               /* Now add the device to the list of devices on the bus. */
+               /* Find the last child of our parent. */
+               for (child = first->bus->children; child && child->sibling; )
+                       child = child->sibling;
+
+               /* Place the chain on the list of children of their parent. */
+               if (child)
+                       child->sibling = first;
+               else
+                       first->bus->children = first;
        }
        return first;
 }
 
+#if OPT_HT_LINK == 1
 static unsigned ht_read_freq_cap(device_t dev, unsigned pos)
 {
-       /* Handle bugs in valid hypertransport frequency reporting */
+       /* Handle bugs in valid hypertransport frequency reporting. */
        unsigned freq_cap;
 
        freq_cap = pci_read_config16(dev, pos);
-       freq_cap &= ~(1 << HT_FREQ_VENDOR); /* Ignore Vendor HT frequencies */
+       freq_cap &= ~(1 << HT_FREQ_VENDOR); /* Ignore Vendor HT frequencies. */
 
-       /* AMD 8131 Errata 48 */
+       /* AMD 8131 Errata 48. */
        if ((dev->vendor == PCI_VENDOR_ID_AMD) &&
-               (dev->device == PCI_DEVICE_ID_AMD_8131_PCIX)) {
+           (dev->device == PCI_DEVICE_ID_AMD_8131_PCIX)) {
                freq_cap &= ~(1 << HT_FREQ_800Mhz);
        }
-       /* AMD 8151 Errata 23 */
+
+       /* AMD 8151 Errata 23. */
        if ((dev->vendor == PCI_VENDOR_ID_AMD) &&
-               (dev->device == PCI_DEVICE_ID_AMD_8151_SYSCTRL)) {
+           (dev->device == PCI_DEVICE_ID_AMD_8151_SYSCTRL)) {
                freq_cap &= ~(1 << HT_FREQ_800Mhz);
        }
-       /* AMD K8 Unsupported 1Ghz? */
+
+       /* AMD K8 unsupported 1GHz? */
        if ((dev->vendor == PCI_VENDOR_ID_AMD) && (dev->device == 0x1100)) {
+#if CONFIG_K8_HT_FREQ_1G_SUPPORT == 1
+
+#if CONFIG_K8_REV_F_SUPPORT == 0
+               /* Only e0 later suupport 1GHz HT. */
+               if (is_cpu_pre_e0())
+                       freq_cap &= ~(1 << HT_FREQ_1000Mhz);
+#endif
+
+#else
                freq_cap &= ~(1 << HT_FREQ_1000Mhz);
+#endif
        }
+
        return freq_cap;
 }
+#endif
 
-struct prev_link {
+struct ht_link {
        struct device *dev;
        unsigned pos;
-       unsigned char config_off, freq_off, freq_cap_off;
+       unsigned char ctrl_off, config_off, freq_off, freq_cap_off;
 };
 
-static int ht_setup_link(struct prev_link *prev, device_t dev, unsigned pos)
+static int ht_setup_link(struct ht_link *prev, device_t dev, unsigned pos)
 {
-       static const uint8_t link_width_to_pow2[]= { 3, 4, 0, 5, 1, 2, 0, 0 };
-       static const uint8_t pow2_to_link_width[] = { 0x7, 4, 5, 0, 1, 3 };
-       unsigned present_width_cap,    upstream_width_cap;
-       unsigned present_freq_cap,     upstream_freq_cap;
-       unsigned ln_present_width_in,  ln_upstream_width_in; 
+#if OPT_HT_LINK == 1
+       static const u8 link_width_to_pow2[] = { 3, 4, 0, 5, 1, 2, 0, 0 };
+       static const u8 pow2_to_link_width[] = { 7, 4, 5, 0, 1, 3 };
+       unsigned present_width_cap, upstream_width_cap;
+       unsigned present_freq_cap, upstream_freq_cap;
+       unsigned ln_present_width_in, ln_upstream_width_in;
        unsigned ln_present_width_out, ln_upstream_width_out;
        unsigned freq, old_freq;
        unsigned present_width, upstream_width, old_width;
+#endif
+       struct ht_link cur[1];
        int reset_needed;
        int linkb_to_host;
 
-       /* Set the hypertransport link width and frequency */
+       /* Set the hypertransport link width and frequency. */
        reset_needed = 0;
-       linkb_to_host = (pci_read_config16(dev, pos + PCI_CAP_FLAGS) >> 10) & 1;
-
-       /* Read the capabilities */
-       present_freq_cap   = ht_read_freq_cap(dev, pos + (linkb_to_host ? PCI_HT_CAP_SLAVE_FREQ_CAP1: PCI_HT_CAP_SLAVE_FREQ_CAP0));
-       upstream_freq_cap  = ht_read_freq_cap(prev->dev, prev->pos + prev->freq_cap_off);
-       present_width_cap  = pci_read_config8(dev, pos + (linkb_to_host ? PCI_HT_CAP_SLAVE_WIDTH1: PCI_HT_CAP_SLAVE_WIDTH0));
-        upstream_width_cap = pci_read_config8(prev->dev, prev->pos + prev->config_off);
-       
-       /* Calculate the highest useable frequency */
+       /*
+        * See which side of the device our previous write to set the unitid
+        * came from.
+        */
+       cur->dev = dev;
+       cur->pos = pos;
+       linkb_to_host =
+         (pci_read_config16(cur->dev, cur->pos + PCI_CAP_FLAGS) >> 10) & 1;
+
+       if (!linkb_to_host) {
+               cur->ctrl_off     = PCI_HT_CAP_SLAVE_CTRL0;
+               cur->config_off   = PCI_HT_CAP_SLAVE_WIDTH0;
+               cur->freq_off     = PCI_HT_CAP_SLAVE_FREQ0;
+               cur->freq_cap_off = PCI_HT_CAP_SLAVE_FREQ_CAP0;
+       } else {
+               cur->ctrl_off     = PCI_HT_CAP_SLAVE_CTRL1;
+               cur->config_off   = PCI_HT_CAP_SLAVE_WIDTH1;
+               cur->freq_off     = PCI_HT_CAP_SLAVE_FREQ1;
+               cur->freq_cap_off = PCI_HT_CAP_SLAVE_FREQ_CAP1;
+       }
+
+#if OPT_HT_LINK == 1
+       /* Read the capabilities. */
+       present_freq_cap =
+               ht_read_freq_cap(cur->dev, cur->pos + cur->freq_cap_off);
+       upstream_freq_cap =
+               ht_read_freq_cap(prev->dev, prev->pos + prev->freq_cap_off);
+       present_width_cap =
+               pci_read_config8(cur->dev, cur->pos + cur->config_off);
+       upstream_width_cap =
+               pci_read_config8(prev->dev, prev->pos + prev->config_off);
+
+       /* Calculate the highest useable frequency. */
        freq = log2(present_freq_cap & upstream_freq_cap);
 
-       /* Calculate the highest width */
+       /* Calculate the highest width. */
        ln_upstream_width_in = link_width_to_pow2[upstream_width_cap & 7];
        ln_present_width_out = link_width_to_pow2[(present_width_cap >> 4) & 7];
-       if (ln_upstream_width_in > ln_present_width_out) {
+       if (ln_upstream_width_in > ln_present_width_out)
                ln_upstream_width_in = ln_present_width_out;
-       }
        upstream_width = pow2_to_link_width[ln_upstream_width_in];
        present_width  = pow2_to_link_width[ln_upstream_width_in] << 4;
 
-       ln_upstream_width_out = link_width_to_pow2[(upstream_width_cap >> 4) & 7];
-       ln_present_width_in   = link_width_to_pow2[present_width_cap & 7];
-       if (ln_upstream_width_out > ln_present_width_in) {
+       ln_upstream_width_out =
+               link_width_to_pow2[(upstream_width_cap >> 4) & 7];
+       ln_present_width_in = link_width_to_pow2[present_width_cap & 7];
+       if (ln_upstream_width_out > ln_present_width_in)
                ln_upstream_width_out = ln_present_width_in;
-       }
        upstream_width |= pow2_to_link_width[ln_upstream_width_out] << 4;
        present_width  |= pow2_to_link_width[ln_upstream_width_out];
 
-       /* Set the current device */
-       old_freq = pci_read_config8(dev, pos + (linkb_to_host ? PCI_HT_CAP_SLAVE_FREQ1:PCI_HT_CAP_SLAVE_FREQ0));
+       /* Set the current device. */
+       old_freq = pci_read_config8(cur->dev, cur->pos + cur->freq_off);
+       old_freq &= 0x0f;
        if (freq != old_freq) {
-               pci_write_config8(dev, pos + (linkb_to_host ? PCI_HT_CAP_SLAVE_FREQ1:PCI_HT_CAP_SLAVE_FREQ0), freq);
+               unsigned new_freq;
+               pci_write_config8(cur->dev, cur->pos + cur->freq_off, freq);
                reset_needed = 1;
-               printk_spew("HyperT FreqP old %x new %x\n",old_freq,freq);
+               printk(BIOS_SPEW, "HyperT FreqP old %x new %x\n",old_freq,freq);
+               new_freq = pci_read_config8(cur->dev, cur->pos + cur->freq_off);
+               new_freq &= 0x0f;
+               if (new_freq != freq) {
+                       printk(BIOS_ERR, "%s Hypertransport frequency would "
+                              "not set. Wanted: %x, got: %x\n",
+                              dev_path(dev), freq, new_freq);
+               }
        }
-       old_width = pci_read_config8(dev, pos + (linkb_to_host ? PCI_HT_CAP_SLAVE_WIDTH1: PCI_HT_CAP_SLAVE_WIDTH0) + 1);
+       old_width = pci_read_config8(cur->dev, cur->pos + cur->config_off + 1);
        if (present_width != old_width) {
-               pci_write_config8(dev, pos + (linkb_to_host ? PCI_HT_CAP_SLAVE_WIDTH1: PCI_HT_CAP_SLAVE_WIDTH0) + 1, present_width);
+               unsigned new_width;
+               pci_write_config8(cur->dev, cur->pos + cur->config_off + 1,
+                                 present_width);
                reset_needed = 1;
-               printk_spew("HyperT widthP old %x new %x\n",old_width, present_width);
+               printk(BIOS_SPEW, "HyperT widthP old %x new %x\n",
+                      old_width, present_width);
+               new_width = pci_read_config8(cur->dev,
+                                            cur->pos + cur->config_off + 1);
+               if (new_width != present_width) {
+                       printk(BIOS_ERR, "%s Hypertransport width would not "
+                              "set. Wanted: %x, got: %x\n",
+                              dev_path(dev), present_width, new_width);
+               }
        }
 
-       /* Set the upstream device */
+       /* Set the upstream device. */
        old_freq = pci_read_config8(prev->dev, prev->pos + prev->freq_off);
        old_freq &= 0x0f;
        if (freq != old_freq) {
+               unsigned new_freq;
                pci_write_config8(prev->dev, prev->pos + prev->freq_off, freq);
                reset_needed = 1;
-               printk_spew("HyperT freqU old %x new %x\n", old_freq, freq);
+               printk(BIOS_SPEW, "HyperT freqU old %x new %x\n",
+                      old_freq, freq);
+               new_freq =
+                 pci_read_config8(prev->dev, prev->pos + prev->freq_off);
+               new_freq &= 0x0f;
+               if (new_freq != freq) {
+                       printk(BIOS_ERR, "%s Hypertransport frequency would "
+                              "not set. Wanted: %x, got: %x\n",
+                              dev_path(prev->dev), freq, new_freq);
+               }
        }
-       old_width = pci_read_config8(prev->dev, prev->pos + prev->config_off + 1);
+       old_width =
+               pci_read_config8(prev->dev, prev->pos + prev->config_off + 1);
        if (upstream_width != old_width) {
-               pci_write_config8(prev->dev, prev->pos + prev->config_off + 1, upstream_width);
+               unsigned new_width;
+               pci_write_config8(prev->dev, prev->pos + prev->config_off + 1,
+                                 upstream_width);
                reset_needed = 1;
-               printk_spew("HyperT widthU old %x new %x\n", old_width, upstream_width);
+               printk(BIOS_SPEW, "HyperT widthU old %x new %x\n", old_width,
+                      upstream_width);
+               new_width = pci_read_config8(prev->dev,
+                                            prev->pos + prev->config_off + 1);
+               if (new_width != upstream_width) {
+                       printk(BIOS_ERR, "%s Hypertransport width would not "
+                              "set. Wanted: %x, got: %x\n",
+                              dev_path(prev->dev), upstream_width, new_width);
+               }
+       }
+#endif
+
+       /*
+        * Remember the current link as the previous link, but look at the
+        * other offsets.
+        */
+       prev->dev = cur->dev;
+       prev->pos = cur->pos;
+       if (cur->ctrl_off == PCI_HT_CAP_SLAVE_CTRL0) {
+               prev->ctrl_off     = PCI_HT_CAP_SLAVE_CTRL1;
+               prev->config_off   = PCI_HT_CAP_SLAVE_WIDTH1;
+               prev->freq_off     = PCI_HT_CAP_SLAVE_FREQ1;
+               prev->freq_cap_off = PCI_HT_CAP_SLAVE_FREQ_CAP1;
+       } else {
+               prev->ctrl_off     = PCI_HT_CAP_SLAVE_CTRL0;
+               prev->config_off   = PCI_HT_CAP_SLAVE_WIDTH0;
+               prev->freq_off     = PCI_HT_CAP_SLAVE_FREQ0;
+               prev->freq_cap_off = PCI_HT_CAP_SLAVE_FREQ_CAP0;
        }
-       
-       /* Remember the current link as the previous link */
-       prev->dev = dev;
-       prev->pos = pos;
-        if(linkb_to_host) {
-               prev->config_off   = PCI_HT_CAP_SLAVE_WIDTH0;
-               prev->freq_off     = PCI_HT_CAP_SLAVE_FREQ0;
-               prev->freq_cap_off = PCI_HT_CAP_SLAVE_FREQ_CAP0;
-        }
-        else {
-               prev->config_off   = PCI_HT_CAP_SLAVE_WIDTH1;
-               prev->freq_off     = PCI_HT_CAP_SLAVE_FREQ1;
-               prev->freq_cap_off = PCI_HT_CAP_SLAVE_FREQ_CAP1;
-        }
 
        return reset_needed;
-               
 }
 
 static unsigned ht_lookup_slave_capability(struct device *dev)
 {
        unsigned pos;
+
        pos = 0;
-       switch(dev->hdr_type & 0x7f) {
-       case PCI_HEADER_TYPE_NORMAL:
-       case PCI_HEADER_TYPE_BRIDGE:
-               pos = PCI_CAPABILITY_LIST;
-               break;
-       }
-       if (pos > PCI_CAP_LIST_NEXT) {
-               pos = pci_read_config8(dev, pos);
-       }
-       while(pos != 0) {   /* loop through the linked list */
-               uint8_t cap;
-               cap = pci_read_config8(dev, pos + PCI_CAP_LIST_ID);
-               printk_spew("Capability: 0x%02x @ 0x%02x\n", cap, pos);
-               if (cap == PCI_CAP_ID_HT) {
-                       unsigned flags;
+       do {
+               pos = pci_find_next_capability(dev, PCI_CAP_ID_HT, pos);
+               if (pos) {
+                       u16 flags;
                        flags = pci_read_config16(dev, pos + PCI_CAP_FLAGS);
-                       printk_spew("flags: 0x%04x\n", (unsigned)flags);
+                       printk(BIOS_SPEW, "flags: 0x%04x\n", flags);
                        if ((flags >> 13) == 0) {
-                               /* Entry is a Slave secondary, success...*/
+                               /* Entry is a slave secondary, success... */
                                break;
                        }
                }
-               pos = pci_read_config8(dev, pos + PCI_CAP_LIST_NEXT);
-       }
+       } while (pos);
+
        return pos;
 }
 
-static void ht_collapse_early_enumeration(struct bus *bus)
+static void ht_collapse_early_enumeration(struct bus *bus,
+                                         unsigned offset_unitid)
 {
        unsigned int devfn;
+       struct ht_link prev;
+       u16 ctrl;
 
-       /* Spin through the devices and collapse any early
-        * hypertransport enumeration.
-        */
-       for(devfn = PCI_DEVFN(1, 0); devfn <= 0xff; devfn += 8) {
+       /* Initialize the hypertransport enumeration state. */
+       prev.dev = bus->dev;
+       prev.pos = bus->cap;
+       prev.ctrl_off     = PCI_HT_CAP_HOST_CTRL;
+       prev.config_off   = PCI_HT_CAP_HOST_WIDTH;
+       prev.freq_off     = PCI_HT_CAP_HOST_FREQ;
+       prev.freq_cap_off = PCI_HT_CAP_HOST_FREQ_CAP;
+
+       /* Wait until the link initialization is complete. */
+       do {
+               ctrl = pci_read_config16(prev.dev, prev.pos + prev.ctrl_off);
+
+               /* Is this the end of the hypertransport chain? */
+               if (ctrl & (1 << 6))
+                       return;
+
+               /* Has the link failed? */
+               if (ctrl & (1 << 4)) {
+                       /*
+                        * Either the link has failed, or we have a CRC error.
+                        * Sometimes this can happen due to link retrain, so
+                        * lets knock it down and see if its transient.
+                        */
+                       ctrl |= ((1 << 4) | (1 << 8)); /* Link fail + CRC */
+                       pci_write_config16(prev.dev, prev.pos + prev.ctrl_off,
+                                          ctrl);
+                       ctrl = pci_read_config16(prev.dev,
+                                                prev.pos + prev.ctrl_off);
+                       if (ctrl & ((1 << 4) | (1 << 8))) {
+                               printk(BIOS_ALERT, "Detected error on "
+                                      "Hypertransport link\n");
+                               return;
+                       }
+               }
+       } while ((ctrl & (1 << 5)) == 0);
+
+       /* Actually, only for one HT device HT chain, and unitid is 0. */
+#if CONFIG_HT_CHAIN_UNITID_BASE == 0
+       if (offset_unitid)
+               return;
+#endif
+
+       /* Check if is already collapsed. */
+       if ((!offset_unitid) || (offset_unitid
+           && (!((CONFIG_HT_CHAIN_END_UNITID_BASE == 0)
+           && (CONFIG_HT_CHAIN_END_UNITID_BASE
+           < CONFIG_HT_CHAIN_UNITID_BASE))))) {
+
+               struct device dummy;
+               u32 id;
+
+               dummy.bus = bus;
+               dummy.path.type = DEVICE_PATH_PCI;
+               dummy.path.pci.devfn = PCI_DEVFN(0, 0);
+
+               id = pci_read_config32(&dummy, PCI_VENDOR_ID);
+               if (!((id == 0xffffffff) || (id == 0x00000000)
+                   || (id == 0x0000ffff) || (id == 0xffff0000))) {
+                       return;
+               }
+       }
+
+       /* Spin through the devices and collapse any early HT enumeration. */
+       for (devfn = PCI_DEVFN(1, 0); devfn <= 0xff; devfn += 8) {
                struct device dummy;
-               uint32_t id;
+               u32 id;
                unsigned pos, flags;
-               dummy.bus              = bus;
-               dummy.path.type        = DEVICE_PATH_PCI;
-               dummy.path.u.pci.devfn = devfn;
+
+               dummy.bus = bus;
+               dummy.path.type = DEVICE_PATH_PCI;
+               dummy.path.pci.devfn = devfn;
+
                id = pci_read_config32(&dummy, PCI_VENDOR_ID);
-               if (id == 0xffffffff || id == 0x00000000 || 
-                       id == 0x0000ffff || id == 0xffff0000) {
+               if ((id == 0xffffffff) || (id == 0x00000000)
+                   || (id == 0x0000ffff) || (id == 0xffff0000)) {
                        continue;
                }
 
                dummy.vendor = id & 0xffff;
                dummy.device = (id >> 16) & 0xffff;
                dummy.hdr_type = pci_read_config8(&dummy, PCI_HEADER_TYPE);
+
                pos = ht_lookup_slave_capability(&dummy);
-               if (!pos){
+               if (!pos)
                        continue;
-               }
 
-               /* Clear the unitid */
+               /* Clear the unitid. */
                flags = pci_read_config16(&dummy, pos + PCI_CAP_FLAGS);
                flags &= ~0x1f;
                pci_write_config16(&dummy, pos + PCI_CAP_FLAGS, flags);
-               printk_spew("Collapsing %s [%04x/%04x]\n", 
-                       dev_path(&dummy), dummy.vendor, dummy.device);
+               printk(BIOS_SPEW, "Collapsing %s [%04x/%04x]\n",
+                      dev_path(&dummy), dummy.vendor, dummy.device);
        }
 }
 
-unsigned int hypertransport_scan_chain(struct bus *bus, unsigned int max)
+unsigned int hypertransport_scan_chain(struct bus *bus, unsigned min_devfn,
+                                      unsigned max_devfn, unsigned int max,
+                                      unsigned *ht_unitid_base,
+                                      unsigned offset_unitid)
 {
-       unsigned next_unitid, last_unitid, previous_unitid;
-       uint8_t previous_pos;
-       device_t old_devices, dev, func, *chain_last;
-       unsigned min_unitid = 1;
-       int reset_needed;
-       struct prev_link prev;
+       /*
+        * Even CONFIG_HT_CHAIN_UNITID_BASE == 0, we still can go through this
+        * function, because of end_of_chain check. Also, we need it to
+        * optimize link.
+        */
+       unsigned int next_unitid, last_unitid, min_unitid, max_unitid;
+       device_t old_devices, dev, func, last_func = 0;
+       struct ht_link prev;
+       int ht_dev_num = 0;
+
+       min_unitid = (offset_unitid) ? CONFIG_HT_CHAIN_UNITID_BASE : 1;
+
+#if CONFIG_HT_CHAIN_END_UNITID_BASE != 0x20
+        /*
+        * Let's record the device of last HT device, so we can set the unitid
+        * to CONFIG_HT_CHAIN_END_UNITID_BASE.
+        */
+       unsigned int real_last_unitid = 0, end_used = 0;
+       u8 real_last_pos = 0;
+       device_t real_last_dev = NULL;
+#endif
 
-       /* Restore the hypertransport chain to it's unitialized state */
-       ht_collapse_early_enumeration(bus);
+       printk(BIOS_INFO, "%s: before ht_collapse_early_enumeration\n", __func__);
+       /* Restore the hypertransport chain to it's unitialized state. */
+       ht_collapse_early_enumeration(bus, offset_unitid);
+       printk(BIOS_INFO, "%s: after  ht_collapse_early_enumeration\n", __func__);
 
-       /* See which static device nodes I have */
+       /* See which static device nodes I have. */
        old_devices = bus->children;
        bus->children = 0;
-       chain_last = &bus->children;
 
-       /* Initialize the hypertransport enumeration state */
-       reset_needed = 0;
+       /* Initialize the hypertransport enumeration state. */
        prev.dev = bus->dev;
        prev.pos = bus->cap;
+
+       prev.ctrl_off     = PCI_HT_CAP_HOST_CTRL;
        prev.config_off   = PCI_HT_CAP_HOST_WIDTH;
        prev.freq_off     = PCI_HT_CAP_HOST_FREQ;
        prev.freq_cap_off = PCI_HT_CAP_HOST_FREQ_CAP;
-       
-       /* If present assign unitid to a hypertransport chain */
+
+       /* If present, assign unitid to a hypertransport chain. */
        last_unitid = min_unitid -1;
-       next_unitid = min_unitid;
-       previous_pos = 0;
+       max_unitid = next_unitid = min_unitid;
        do {
-               uint32_t id, class;
-               uint8_t hdr_type, pos;
-               uint16_t flags;
-               unsigned count, static_count;
+               u8 pos;
+               u16 flags, ctrl;
+               unsigned int count, static_count;
 
-               previous_unitid = last_unitid;
                last_unitid = next_unitid;
 
-               /* Get setup the device_structure */
+               /* Wait until the link initialization is complete. */
+               do {
+                       ctrl = pci_read_config16(prev.dev,
+                                                prev.pos + prev.ctrl_off);
+
+                       /* End of chain? */
+                       if (ctrl & (1 << 6))
+                               goto end_of_chain;
+
+                       if (ctrl & ((1 << 4) | (1 << 8))) {
+                               /*
+                                * Either the link has failed, or we have a CRC
+                                * error. Sometimes this can happen due to link
+                                * retrain, so lets knock it down and see if
+                                * it's transient.
+                                */
+                               ctrl |= ((1 << 4) | (1 <<8)); // Link fail + CRC
+                               pci_write_config16(prev.dev,
+                                       prev.pos + prev.ctrl_off, ctrl);
+                               ctrl = pci_read_config16(prev.dev,
+                                               prev.pos + prev.ctrl_off);
+                               if (ctrl & ((1 << 4) | (1 << 8))) {
+                                       printk(BIOS_ALERT, "Detected error on "
+                                              "hypertransport link\n");
+                                       goto end_of_chain;
+                               }
+                       }
+               } while ((ctrl & (1 << 5)) == 0);
+
+
+               printk(BIOS_INFO, "%s: before ht_scan_get_devs\n", __func__);
+               /* Get and setup the device_structure. */
                dev = ht_scan_get_devs(&old_devices);
+               printk(BIOS_INFO, "%s: after  ht_scan_get_devs\n", __func__);
 
-               if (!dev) {
-                       struct device dummy;
-                       dummy.bus              = bus;
-                       dummy.path.type        = DEVICE_PATH_PCI;
-                       dummy.path.u.pci.devfn = 0;
-                       id = pci_read_config32(&dummy, PCI_VENDOR_ID);
-                       /* If the chain is fully enumerated quit */
-                       if (id == 0xffffffff || id == 0x00000000 ||
-                               id == 0x0000ffff || id == 0xffff0000) {
-                               break;
-                       }
-                       dev = alloc_dev(bus, &dummy.path);
-               }
-               else {
-                       /* Add this device to the pci bus chain */
-                       *chain_last = dev;
-                       /* Run the magice enable sequence for the device */
-                       if (dev->chip_ops && dev->chip_ops->enable_dev) {
-                               dev->chip_ops->enable_dev(dev);
-                       }
-                       /* Now read the vendor and device id */
-                       id = pci_read_config32(dev, PCI_VENDOR_ID);
-
-                       /* If the chain is fully enumerated quit */
-                       if (id == 0xffffffff || id == 0x00000000 ||
-                               id == 0x0000ffff || id == 0xffff0000) {
-                                      if (dev->enabled) {
-                                              printk_info("Disabling static device: %s\n",
-                                                      dev_path(dev));
-                                              dev->enabled = 0;
-                                       }
-                               break;
-                       }
-               }
-               /* Update the device chain tail */
-               for(func = dev; func; func = func->sibling) {
-                       chain_last = &func->sibling;
-               }
-               
-               /* Read the rest of the pci configuration information */
-               hdr_type = pci_read_config8(dev, PCI_HEADER_TYPE);
-               class = pci_read_config32(dev, PCI_CLASS_REVISION);
-               
-               /* Store the interesting information in the device structure */
-               dev->vendor = id & 0xffff;
-               dev->device = (id >> 16) & 0xffff;
-               dev->hdr_type = hdr_type;
-               /* class code, the upper 3 bytes of PCI_CLASS_REVISION */
-               dev->class = class >> 8;
-
-               /* Find the hypertransport link capability */
+               /* See if a device is present and setup the device structure. */
+               printk(BIOS_INFO, "%s: before pci_probe_dev\n", __func__);
+               dev = pci_probe_dev(dev, bus, 0);
+               printk(BIOS_INFO, "%s: after  pci_probe_dev\n", __func__);
+               if (!dev || !dev->enabled)
+                       break;
+
+               /* Find the hypertransport link capability. */
+               printk(BIOS_INFO, "%s: before ht_lookup_slave_capability\n", __func__);
                pos = ht_lookup_slave_capability(dev);
+               printk(BIOS_INFO, "%s: after  ht_lookup_slave_capability\n", __func__);
                if (pos == 0) {
-                       printk_err("%s Hypertransport link capability not found", 
-                               dev_path(dev));
+                       printk(BIOS_ERR, "%s Hypertransport link capability "
+                              "not found", dev_path(dev));
                        break;
                }
-               
 
-               /* Update the Unitid of the current device */
+               /* Update the unitid of the current device. */
                flags = pci_read_config16(dev, pos + PCI_CAP_FLAGS);
-               flags &= ~0x1f; /* mask out base Unit ID */
+
+               /*
+                * If the devices has a unitid set and is at devfn 0 we are
+                * done. This can happen with shadow hypertransport devices,
+                * or if we have reached the bottom of a HT device chain.
+                */
+               if (flags & 0x1f)
+                       break;
+
+               flags &= ~0x1f; /* Mask out base Unit ID. */
+
+               count = (flags >> 5) & 0x1f; /* Het unit count. */
+
+#if CONFIG_HT_CHAIN_END_UNITID_BASE != 0x20
+               if (offset_unitid) {
+                       /* max_devfn will be (0x17<<3)|7 or (0x1f<<3)|7. */
+                       if (next_unitid > (max_devfn >> 3)) {
+                               if (!end_used) {
+                                       next_unitid =
+                                         CONFIG_HT_CHAIN_END_UNITID_BASE;
+                                       end_used = 1;
+                               } else {
+                                       goto end_of_chain;
+                               }
+                       }
+               }
+#endif
+
                flags |= next_unitid & 0x1f;
                pci_write_config16(dev, pos + PCI_CAP_FLAGS, flags);
 
-               /* Update the Unitd id in the device structure */
+               /* Update the unitid in the device structure. */
                static_count = 1;
-               for(func = dev; func; func = func->sibling) {
-                       func->path.u.pci.devfn += (next_unitid << 3);
-                       static_count = (func->path.u.pci.devfn >> 3) 
-                               - (dev->path.u.pci.devfn >> 3) + 1;
+               for (func = dev; func; func = func->sibling) {
+                       func->path.pci.devfn += (next_unitid << 3);
+                       static_count = (func->path.pci.devfn >> 3)
+                                       - (dev->path.pci.devfn >> 3) + 1;
+                       last_func = func;
                }
 
-               /* Compute the number of unitids consumed */
-               count = (flags >> 5) & 0x1f; /* get unit count */
-               printk_spew("%s count: %04x static_count: %04x\n", 
-                       dev_path(dev), count, static_count);
-               if (count < static_count) {
+               /* Compute the number of unitids consumed. */
+               printk(BIOS_SPEW, "%s count: %04x static_count: %04x\n",
+                      dev_path(dev), count, static_count);
+               if (count < static_count)
                        count = static_count;
-               }
 
-               /* Update the Unitid of the next device */
+               /* Update the unitid of the next device. */
+               ht_unitid_base[ht_dev_num] = next_unitid;
+               ht_dev_num++;
+
+#if CONFIG_HT_CHAIN_END_UNITID_BASE != 0x20
+               if (offset_unitid) {
+                       real_last_pos = pos;
+                       real_last_unitid = next_unitid;
+                       real_last_dev = dev;
+               }
+#endif
                next_unitid += count;
+               if (next_unitid > max_unitid)
+                       max_unitid = next_unitid;
 
-               /* Setup the hypetransport link */
-               reset_needed |= ht_setup_link(&prev, dev, pos);
+               /* Setup the hypetransport link. */
+               printk(BIOS_INFO, "%s: before ht_setup_link\n", __func__);
+               bus->reset_needed |= ht_setup_link(&prev, dev, pos);
+               printk(BIOS_INFO, "%s: after  ht_setup_link\n", __func__);
 
-               printk_debug("%s [%04x/%04x] %s next_unitid: %04x\n",
-                       dev_path(dev),
-                       dev->vendor, dev->device, 
-                       (dev->enabled? "enabled": "disabled"), next_unitid);
+               printk(BIOS_DEBUG, "%s [%04x/%04x] %s next_unitid: %04x\n",
+                      dev_path(dev), dev->vendor, dev->device,
+                      (dev->enabled? "enabled" : "disabled"), next_unitid);
 
-       } while((last_unitid != next_unitid) && (next_unitid <= 0x1f));
-#if HAVE_HARD_RESET == 1
-       if(reset_needed) {
-               printk_info("HyperT reset needed\n");
-               hard_reset();
-       }
-       else {
-               printk_debug("HyperT reset not needed\n");
+       } while (last_unitid != next_unitid);
+
+end_of_chain:
+
+       printk(BIOS_INFO, "%s: end_of_chain.  w00t!\n", __func__);
+#if OPT_HT_LINK == 1
+       if (bus->reset_needed)
+               printk(BIOS_INFO, "HyperT reset needed\n");
+       else
+               printk(BIOS_DEBUG, "HyperT reset not needed\n");
+#endif
+
+#if CONFIG_HT_CHAIN_END_UNITID_BASE != 0x20
+       if (offset_unitid && (ht_dev_num > 1)
+           && (real_last_unitid != CONFIG_HT_CHAIN_END_UNITID_BASE)
+           && !end_used) {
+               u16 flags;
+               flags = pci_read_config16(real_last_dev,
+                                         real_last_pos + PCI_CAP_FLAGS);
+               flags &= ~0x1f;
+               flags |= CONFIG_HT_CHAIN_END_UNITID_BASE & 0x1f;
+               pci_write_config16(real_last_dev,
+                                  real_last_pos + PCI_CAP_FLAGS, flags);
+
+               for (func = real_last_dev; func; func = func->sibling) {
+                       func->path.pci.devfn -= ((real_last_unitid
+                               - CONFIG_HT_CHAIN_END_UNITID_BASE) << 3);
+                       last_func = func;
+               }
+
+               /* Update last one. */
+               ht_unitid_base[ht_dev_num-1] = CONFIG_HT_CHAIN_END_UNITID_BASE;
+
+               printk(BIOS_DEBUG, " unitid: %04x --> %04x\n",
+                      real_last_unitid, CONFIG_HT_CHAIN_END_UNITID_BASE);
        }
 #endif
-       if (next_unitid > 0x1f) {
-               next_unitid = 0x1f;
+       next_unitid = max_unitid;
+
+       if (next_unitid > 0x20)
+               next_unitid = 0x20;
+
+       if ((bus->secondary == 0) && (next_unitid > 0x18))
+               next_unitid = 0x18; /* Avoid K8 on bus 0. */
+
+       /*
+        * Die if any leftover static devices are are found. There's probably
+        * a problem in devicetree.cb.
+        */
+       if (old_devices) {
+               device_t left;
+               for (left = old_devices; left; left = left->sibling)
+                       printk(BIOS_DEBUG, "%s\n", dev_path(left));
+
+               printk(BIOS_ERR, "HT: Leftover static devices. "
+                      "Check your devicetree.cb\n");
+
+               /*
+                * Put back the leftover static device, and let pci_scan_bus()
+                * disable it.
+                */
+               if (last_func && !last_func->sibling)
+                       last_func->sibling = old_devices;
        }
-       return pci_scan_bus(bus, 0x00, (next_unitid << 3)|7, max);
+
+       printk(BIOS_INFO, "%s: before pci_scan_bus!\n", __func__);
+       /* Now that nothing is overlapping it is safe to scan the children. */
+       max = pci_scan_bus(bus, 0x00, ((next_unitid - 1) << 3) | 7, max);
+       printk(BIOS_INFO, "%s: after  pci_scan_bus!\n", __func__);
+       return max;
+}
+
+/**
+ * Scan a PCI bridge and the buses behind the bridge.
+ *
+ * Determine the existence of buses behind the bridge. Set up the bridge
+ * according to the result of the scan.
+ *
+ * This function is the default scan_bus() method for PCI bridge devices.
+ *
+ * @param bus TODO
+ * @param min_devfn TODO
+ * @param max_devfn TODO
+ * @param max The highest bus number assgined up to now.
+ * @return The maximum bus number found, after scanning all subordinate busses.
+ */
+static unsigned int hypertransport_scan_chain_x(struct bus *bus,
+       unsigned int min_devfn, unsigned int max_devfn, unsigned int max)
+{
+       unsigned int ht_unitid_base[4];
+       unsigned int offset_unitid = 1;
+       return hypertransport_scan_chain(bus, min_devfn, max_devfn, max,
+                                        ht_unitid_base, offset_unitid);
 }
+
+unsigned int ht_scan_bridge(struct device *dev, unsigned int max)
+{
+       return do_pci_scan_bridge(dev, max, hypertransport_scan_chain_x);
+}
+
+/** Default device operations for hypertransport bridges */
+static struct pci_operations ht_bus_ops_pci = {
+       .set_subsystem = 0,
+};
+
+struct device_operations default_ht_ops_bus = {
+       .read_resources   = pci_bus_read_resources,
+       .set_resources    = pci_dev_set_resources,
+       .enable_resources = pci_bus_enable_resources,
+       .init             = 0,
+       .scan_bus         = ht_scan_bridge,
+       .enable           = 0,
+       .reset_bus        = pci_bus_reset,
+       .ops_pci          = &ht_bus_ops_pci,
+};