[PATCH 24/27] powerpc: Cell "Spider" MMIO workarounds
Benjamin Herrenschmidt
benh at kernel.crashing.org
Mon Nov 6 18:05:56 EST 2006
This is totally untested, I just put it together quickly, but gives an
example of how the hooks can be used which is why I introduced it in
this serie. Hopefully, I'll test & fix it up properly this week.
This patch implements a workaround for a Spider PCI host bridge bug
where it doesn't enforce some of the PCI ordering rules unless some
manual manipulation of a special register is done. In order to be
fully compliant with the PCI spec, I do this on every MMIO read
operation.
Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>
arch/powerpc/Kconfig | 1
arch/powerpc/platforms/cell/Makefile | 3
arch/powerpc/platforms/cell/io-workarounds.c | 205 +++++++++++++++++++++++++++
3 files changed, 208 insertions(+), 1 deletion(-)
Index: linux-cell/arch/powerpc/platforms/cell/io-workarounds.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-cell/arch/powerpc/platforms/cell/io-workarounds.c 2006-11-06 15:47:42.000000000 +1100
@@ -0,0 +1,205 @@
+#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 MAX_SPIDERS 2
+
+static struct spider_pci_bus {
+ void __iomem *dummy_reg;
+ 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;
+
+ /* Fast path if we have a token, else we need to
+ * translate the virtual address and do a linear
+ * search
+ */
+ token = PCI_GET_ADDR_TOKEN(addr);
+ if (token)
+ 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 MMIO and PIO */
+ if (vaddr < VMALLOC_START || vaddr >= IMALLOC_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 (yuck). Dbl-check what we are doing
+ * here, spec is unclear to me
+ */
+ out_le32(bus->dummy_reg, 0x80000000);
+ (void)in_le32(bus->dummy_reg + 4);
+}
+
+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 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);
+
+ bus = spider_pci_find(0, addr);
+ if (bus != NULL)
+ PCI_SET_ADDR_TOKEN(res, bus - spider_pci_busses + 1);
+ return res;
+}
+
+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;
+ }
+
+ /* Map them. XXX Dbl-check the registers, spec is unclear to me */
+ regs = ioremap(rsrc.start + 0xd810, 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->dummy_reg = regs;
+}
+
+static int __init spider_pci_workaround_init(void)
+{
+ struct pci_controller *phb;
+
+ /* 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 = 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.readb = spider_readb;
+ ppc_pci_io.readw = spider_readw;
+ ppc_pci_io.readl = spider_readl;
+ ppc_pci_io.readq = spider_readq;
+ ppc_pci_io.memcpy_fromio = spider_memcpy_fromio;
+
+ /* Setup ioremap callback */
+ ppc_md.ioremap = spider_ioremap;
+
+ return 0;
+}
+arch_initcall(spider_pci_workaround_init);
Index: linux-cell/arch/powerpc/Kconfig
===================================================================
--- linux-cell.orig/arch/powerpc/Kconfig 2006-11-06 15:47:35.000000000 +1100
+++ linux-cell/arch/powerpc/Kconfig 2006-11-06 15:48:07.000000000 +1100
@@ -468,6 +468,7 @@ config PPC_CELL_NATIVE
select PPC_CELL
select PPC_DCR_MMIO
select PPC_OF_PLATFORM_PCI
+ select PPC_INDIRECT_IO
select MPIC
default n
Index: linux-cell/arch/powerpc/platforms/cell/Makefile
===================================================================
--- linux-cell.orig/arch/powerpc/platforms/cell/Makefile 2006-11-06 15:18:35.000000000 +1100
+++ linux-cell/arch/powerpc/platforms/cell/Makefile 2006-11-06 15:47:42.000000000 +1100
@@ -1,5 +1,6 @@
obj-$(CONFIG_PPC_CELL_NATIVE) += interrupt.o iommu.o setup.o \
- cbe_regs.o spider-pic.o pervasive.o
+ cbe_regs.o spider-pic.o \
+ pervasive.o io-workarounds.o
obj-$(CONFIG_CBE_RAS) += ras.o
ifeq ($(CONFIG_SMP),y)
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