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io-workarounds.c

/*
 *  Copyright (C) 2006 Benjamin Herrenschmidt <benh@kernel.crashing.org>
 *                 IBM, Corp.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#undef DEBUG

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/pci.h>
#include <asm/io.h>
#include <asm/machdep.h>
#include <asm/pci-bridge.h>
#include <asm/ppc-pci.h>


#define SPIDER_PCI_REG_BASE         0xd000
#define SPIDER_PCI_VCI_CNTL_STAT    0x0110
#define SPIDER_PCI_DUMMY_READ       0x0810
#define SPIDER_PCI_DUMMY_READ_BASE  0x0814

/* Undefine that to re-enable bogus prefetch
 *
 * Without that workaround, the chip will do bogus prefetch past
 * page boundary from system memory. This setting will disable that,
 * though the documentation is unclear as to the consequences of doing
 * so, either purely performances, or possible misbehaviour... It's not
 * clear wether the chip can handle unaligned accesses at all without
 * prefetching enabled.
 *
 * For now, things appear to be behaving properly with that prefetching
 * disabled and IDE, possibly because IDE isn't doing any unaligned
 * access.
 */
#define SPIDER_DISABLE_PREFETCH

#define MAX_SPIDERS     3

static struct spider_pci_bus {
      void __iomem      *regs;
      unsigned long     mmio_start;
      unsigned long     mmio_end;
      unsigned long     pio_vstart;
      unsigned long     pio_vend;
} spider_pci_busses[MAX_SPIDERS];
static int spider_pci_count;

static struct spider_pci_bus *spider_pci_find(unsigned long vaddr,
                                    unsigned long paddr)
{
      int i;

      for (i = 0; i < spider_pci_count; i++) {
            struct spider_pci_bus *bus = &spider_pci_busses[i];
            if (paddr && paddr >= bus->mmio_start && paddr < bus->mmio_end)
                  return bus;
            if (vaddr && vaddr >= bus->pio_vstart && vaddr < bus->pio_vend)
                  return bus;
      }
      return NULL;
}

static void spider_io_flush(const volatile void __iomem *addr)
{
      struct spider_pci_bus *bus;
      int token;

      /* Get platform token (set by ioremap) from address */
      token = PCI_GET_ADDR_TOKEN(addr);

      /* Fast path if we have a non-0 token, it indicates which bus we
       * are on.
       *
       * If the token is 0, that means either that the ioremap was done
       * before we initialized this layer, or it's a PIO operation. We
       * fallback to a low path in this case. Hopefully, internal devices
       * which are ioremap'ed early should use in_XX/out_XX functions
       * instead of the PCI ones and thus not suffer from the slowdown.
       *
       * Also note that currently, the workaround will not work for areas
       * that are not mapped with PTEs (bolted in the hash table). This
       * is the case for ioremaps done very early at boot (before
       * mem_init_done) and includes the mapping of the ISA IO space.
       *
       * Fortunately, none of the affected devices is expected to do DMA
       * and thus there should be no problem in practice.
       *
       * In order to improve performances, we only do the PTE search for
       * addresses falling in the PHB IO space area. That means it will
       * not work for hotplug'ed PHBs but those don't exist with Spider.
       */
      if (token && token <= spider_pci_count)
            bus = &spider_pci_busses[token - 1];
      else {
            unsigned long vaddr, paddr;
            pte_t *ptep;

            /* Fixup physical address */
            vaddr = (unsigned long)PCI_FIX_ADDR(addr);

            /* Check if it's in allowed range for  PIO */
            if (vaddr < PHB_IO_BASE || vaddr > PHB_IO_END)
                  return;

            /* Try to find a PTE. If not, clear the paddr, we'll do
             * a vaddr only lookup (PIO only)
             */
            ptep = find_linux_pte(init_mm.pgd, vaddr);
            if (ptep == NULL)
                  paddr = 0;
            else
                  paddr = pte_pfn(*ptep) << PAGE_SHIFT;

            bus = spider_pci_find(vaddr, paddr);
            if (bus == NULL)
                  return;
      }

      /* Now do the workaround
       */
      (void)in_be32(bus->regs + SPIDER_PCI_DUMMY_READ);
}

static u8 spider_readb(const volatile void __iomem *addr)
{
      u8 val = __do_readb(addr);
      spider_io_flush(addr);
      return val;
}

static u16 spider_readw(const volatile void __iomem *addr)
{
      u16 val = __do_readw(addr);
      spider_io_flush(addr);
      return val;
}

static u32 spider_readl(const volatile void __iomem *addr)
{
      u32 val = __do_readl(addr);
      spider_io_flush(addr);
      return val;
}

static u64 spider_readq(const volatile void __iomem *addr)
{
      u64 val = __do_readq(addr);
      spider_io_flush(addr);
      return val;
}

static u16 spider_readw_be(const volatile void __iomem *addr)
{
      u16 val = __do_readw_be(addr);
      spider_io_flush(addr);
      return val;
}

static u32 spider_readl_be(const volatile void __iomem *addr)
{
      u32 val = __do_readl_be(addr);
      spider_io_flush(addr);
      return val;
}

static u64 spider_readq_be(const volatile void __iomem *addr)
{
      u64 val = __do_readq_be(addr);
      spider_io_flush(addr);
      return val;
}

static void spider_readsb(const volatile void __iomem *addr, void *buf,
                    unsigned long count)
{
      __do_readsb(addr, buf, count);
      spider_io_flush(addr);
}

static void spider_readsw(const volatile void __iomem *addr, void *buf,
                    unsigned long count)
{
      __do_readsw(addr, buf, count);
      spider_io_flush(addr);
}

static void spider_readsl(const volatile void __iomem *addr, void *buf,
                    unsigned long count)
{
      __do_readsl(addr, buf, count);
      spider_io_flush(addr);
}

static void spider_memcpy_fromio(void *dest, const volatile void __iomem *src,
                         unsigned long n)
{
      __do_memcpy_fromio(dest, src, n);
      spider_io_flush(src);
}


static void __iomem * spider_ioremap(unsigned long addr, unsigned long size,
                             unsigned long flags)
{
      struct spider_pci_bus *bus;
      void __iomem *res = __ioremap(addr, size, flags);
      int busno;

      pr_debug("spider_ioremap(0x%lx, 0x%lx, 0x%lx) -> 0x%p\n",
             addr, size, flags, res);

      bus = spider_pci_find(0, addr);
      if (bus != NULL) {
            busno = bus - spider_pci_busses;
            pr_debug(" found bus %d, setting token\n", busno);
            PCI_SET_ADDR_TOKEN(res, busno + 1);
      }
      pr_debug(" result=0x%p\n", res);

      return res;
}

static void __init spider_pci_setup_chip(struct spider_pci_bus *bus)
{
#ifdef SPIDER_DISABLE_PREFETCH
      u32 val = in_be32(bus->regs + SPIDER_PCI_VCI_CNTL_STAT);
      pr_debug(" PVCI_Control_Status was 0x%08x\n", val);
      out_be32(bus->regs + SPIDER_PCI_VCI_CNTL_STAT, val | 0x8);
#endif

      /* Configure the dummy address for the workaround */
      out_be32(bus->regs + SPIDER_PCI_DUMMY_READ_BASE, 0x80000000);
}

static void __init spider_pci_add_one(struct pci_controller *phb)
{
      struct spider_pci_bus *bus = &spider_pci_busses[spider_pci_count];
      struct device_node *np = phb->arch_data;
      struct resource rsrc;
      void __iomem *regs;

      if (spider_pci_count >= MAX_SPIDERS) {
            printk(KERN_ERR "Too many spider bridges, workarounds"
                   " disabled for %s\n", np->full_name);
            return;
      }

      /* Get the registers for the beast */
      if (of_address_to_resource(np, 0, &rsrc)) {
            printk(KERN_ERR "Failed to get registers for spider %s"
                   " workarounds disabled\n", np->full_name);
            return;
      }

      /* Mask out some useless bits in there to get to the base of the
       * spider chip
       */
      rsrc.start &= ~0xfffffffful;

      /* Map them */
      regs = ioremap(rsrc.start + SPIDER_PCI_REG_BASE, 0x1000);
      if (regs == NULL) {
            printk(KERN_ERR "Failed to map registers for spider %s"
                   " workarounds disabled\n", np->full_name);
            return;
      }

      spider_pci_count++;

      /* We assume spiders only have one MMIO resource */
      bus->mmio_start = phb->mem_resources[0].start;
      bus->mmio_end = phb->mem_resources[0].end + 1;

      bus->pio_vstart = (unsigned long)phb->io_base_virt;
      bus->pio_vend = bus->pio_vstart + phb->pci_io_size;

      bus->regs = regs;

      printk(KERN_INFO "PCI: Spider MMIO workaround for %s\n",np->full_name);

      pr_debug(" mmio (P) = 0x%016lx..0x%016lx\n",
             bus->mmio_start, bus->mmio_end);
      pr_debug("  pio (V) = 0x%016lx..0x%016lx\n",
             bus->pio_vstart, bus->pio_vend);
      pr_debug(" regs (P) = 0x%016lx (V) = 0x%p\n",
             rsrc.start + SPIDER_PCI_REG_BASE, bus->regs);

      spider_pci_setup_chip(bus);
}

static struct ppc_pci_io __initdata spider_pci_io = {
      .readb = spider_readb,
      .readw = spider_readw,
      .readl = spider_readl,
      .readq = spider_readq,
      .readw_be = spider_readw_be,
      .readl_be = spider_readl_be,
      .readq_be = spider_readq_be,
      .readsb = spider_readsb,
      .readsw = spider_readsw,
      .readsl = spider_readsl,
      .memcpy_fromio = spider_memcpy_fromio,
};

static int __init spider_pci_workaround_init(void)
{
      struct pci_controller *phb;

      if (!machine_is(cell))
            return 0;

      /* Find spider bridges. We assume they have been all probed
       * in setup_arch(). If that was to change, we would need to
       * update this code to cope with dynamically added busses
       */
      list_for_each_entry(phb, &hose_list, list_node) {
            struct device_node *np = phb->arch_data;
            const char *model = of_get_property(np, "model", NULL);

            /* If no model property or name isn't exactly "pci", skip */
            if (model == NULL || strcmp(np->name, "pci"))
                  continue;
            /* If model is not "Spider", skip */
            if (strcmp(model, "Spider"))
                  continue;
            spider_pci_add_one(phb);
      }

      /* No Spider PCI found, exit */
      if (spider_pci_count == 0)
            return 0;

      /* Setup IO callbacks. We only setup MMIO reads. PIO reads will
       * fallback to MMIO reads (though without a token, thus slower)
       */
      ppc_pci_io = spider_pci_io;

      /* Setup ioremap callback */
      ppc_md.ioremap = spider_ioremap;

      return 0;
}
arch_initcall(spider_pci_workaround_init);

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