[PATCH] powerpc: Add OF address parsing code (#2)

Parsing addresses extracted from Open Firmware isn't a simple matter. We
have various bits of code that try to do it in various place, including
some heuristics in prom.c that pre-parse addresses at boot and fill
device-nodes "addrs", but those are dodgy at best and I want to
deprecate them. So this patch introduces a new set of routines that
should be capable of parsing most types of addresses and translating
them into CPU physical addresses. It currently works for things on PCI
busses and ISA busses and should work on "standard" busses like the root
bus or the MacIO bus that don't put funky flags in addresses. If you
have other bus types that do use funky flags, you'll have to add new bus
type translators, which is fairly easy.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

2 files changed, 422 insertions, 1 deletions

diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 78f7b90..aab0ae3 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -12,7 +12,8 @@ CFLAGS_btext.o		+= -fPIC
 endif
 
 obj-y				:= semaphore.o cputable.o ptrace.o syscalls.o \
-				   irq.o align.o signal_32.o pmc.o vdso.o
+				   irq.o align.o signal_32.o pmc.o vdso.o \
+				   prom_parse.o
 obj-y				+= vdso32/
 obj-$(CONFIG_PPC64)		+= setup_64.o binfmt_elf32.o sys_ppc32.o \
 				   signal_64.o ptrace32.o systbl.o \
diff --git a/arch/powerpc/kernel/prom_parse.c b/arch/powerpc/kernel/prom_parse.c
new file mode 100644
index 0000000..9c2a5be
--- /dev/null
+++ b/arch/powerpc/kernel/prom_parse.c
@@ -0,0 +1,420 @@
+#undef DEBUG
+
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/pci_regs.h>
+#include <linux/module.h>
+#include <asm/prom.h>
+
+#ifdef DEBUG
+#define DBG(fmt...) do { printk(fmt); } while(0)
+#else
+#define DBG(fmt...) do { } while(0)
+#endif
+
+#ifdef CONFIG_PPC64
+#define PRu64	"%lx"
+#else
+#define PRu64	"%llx"
+#endif
+
+/* Max address size we deal with */
+#define OF_MAX_ADDR_CELLS	4
+#define OF_CHECK_COUNTS(na, ns)	((na) > 0 && (na) <= OF_MAX_ADDR_CELLS && \
+			(ns) > 0)
+
+/* Debug utility */
+#ifdef DEBUG
+static void of_dump_addr(const char *s, u32 *addr, int na)
+{
+	printk("%s", s);
+	while(na--)
+		printk(" %08x", *(addr++));
+	printk("\n");
+}
+#else
+static void of_dump_addr(const char *s, u32 *addr, int na) { }
+#endif
+
+/* Read a big address */
+static inline u64 of_read_addr(u32 *cell, int size)
+{
+	u64 r = 0;
+	while (size--)
+		r = (r << 32) | *(cell++);
+	return r;
+}
+
+/* Callbacks for bus specific translators */
+struct of_bus {
+	const char	*name;
+	const char	*addresses;
+	int		(*match)(struct device_node *parent);
+	void		(*count_cells)(struct device_node *child,
+				       int *addrc, int *sizec);
+	u64		(*map)(u32 *addr, u32 *range, int na, int ns, int pna);
+	int		(*translate)(u32 *addr, u64 offset, int na);
+};
+
+
+/*
+ * Default translator (generic bus)
+ */
+
+static void of_default_count_cells(struct device_node *dev,
+				   int *addrc, int *sizec)
+{
+	if (addrc)
+		*addrc = prom_n_addr_cells(dev);
+	if (sizec)
+		*sizec = prom_n_size_cells(dev);
+}
+
+static u64 of_default_map(u32 *addr, u32 *range, int na, int ns, int pna)
+{
+	u64 cp, s, da;
+
+	cp = of_read_addr(range, na);
+	s  = of_read_addr(range + na + pna, ns);
+	da = of_read_addr(addr, na);
+
+	DBG("OF: default map, cp="PRu64", s="PRu64", da="PRu64"\n",
+	    cp, s, da);
+
+	if (da < cp || da >= (cp + s))
+		return OF_BAD_ADDR;
+	return da - cp;
+}
+
+static int of_default_translate(u32 *addr, u64 offset, int na)
+{
+	u64 a = of_read_addr(addr, na);
+	memset(addr, 0, na * 4);
+	a += offset;
+	if (na > 1)
+		addr[na - 2] = a >> 32;
+	addr[na - 1] = a & 0xffffffffu;
+
+	return 0;
+}
+
+
+/*
+ * PCI bus specific translator
+ */
+
+static int of_bus_pci_match(struct device_node *np)
+{
+	return !strcmp(np->type, "pci");
+}
+
+static void of_bus_pci_count_cells(struct device_node *np,
+				   int *addrc, int *sizec)
+{
+	if (addrc)
+		*addrc = 3;
+	if (sizec)
+		*sizec = 2;
+}
+
+static u64 of_bus_pci_map(u32 *addr, u32 *range, int na, int ns, int pna)
+{
+	u64 cp, s, da;
+
+	/* Check address type match */
+	if ((addr[0] ^ range[0]) & 0x03000000)
+		return OF_BAD_ADDR;
+
+	/* Read address values, skipping high cell */
+	cp = of_read_addr(range + 1, na - 1);
+	s  = of_read_addr(range + na + pna, ns);
+	da = of_read_addr(addr + 1, na - 1);
+
+	DBG("OF: PCI map, cp="PRu64", s="PRu64", da="PRu64"\n", cp, s, da);
+
+	if (da < cp || da >= (cp + s))
+		return OF_BAD_ADDR;
+	return da - cp;
+}
+
+static int of_bus_pci_translate(u32 *addr, u64 offset, int na)
+{
+	return of_default_translate(addr + 1, offset, na - 1);
+}
+
+/*
+ * ISA bus specific translator
+ */
+
+static int of_bus_isa_match(struct device_node *np)
+{
+	return !strcmp(np->name, "isa");
+}
+
+static void of_bus_isa_count_cells(struct device_node *child,
+				   int *addrc, int *sizec)
+{
+	if (addrc)
+		*addrc = 2;
+	if (sizec)
+		*sizec = 1;
+}
+
+static u64 of_bus_isa_map(u32 *addr, u32 *range, int na, int ns, int pna)
+{
+	u64 cp, s, da;
+
+	/* Check address type match */
+	if ((addr[0] ^ range[0]) & 0x00000001)
+		return OF_BAD_ADDR;
+
+	/* Read address values, skipping high cell */
+	cp = of_read_addr(range + 1, na - 1);
+	s  = of_read_addr(range + na + pna, ns);
+	da = of_read_addr(addr + 1, na - 1);
+
+	DBG("OF: ISA map, cp="PRu64", s="PRu64", da="PRu64"\n", cp, s, da);
+
+	if (da < cp || da >= (cp + s))
+		return OF_BAD_ADDR;
+	return da - cp;
+}
+
+static int of_bus_isa_translate(u32 *addr, u64 offset, int na)
+{
+	return of_default_translate(addr + 1, offset, na - 1);
+}
+
+/*
+ * Array of bus specific translators
+ */
+
+static struct of_bus of_busses[] = {
+	/* PCI */
+	{
+		.name = "pci",
+		.addresses = "assigned-addresses",
+		.match = of_bus_pci_match,
+		.count_cells = of_bus_pci_count_cells,
+		.map = of_bus_pci_map,
+		.translate = of_bus_pci_translate,
+	},
+	/* ISA */
+	{
+		.name = "isa",
+		.addresses = "reg",
+		.match = of_bus_isa_match,
+		.count_cells = of_bus_isa_count_cells,
+		.map = of_bus_isa_map,
+		.translate = of_bus_isa_translate,
+	},
+	/* Default */
+	{
+		.name = "default",
+		.addresses = "reg",
+		.match = NULL,
+		.count_cells = of_default_count_cells,
+		.map = of_default_map,
+		.translate = of_default_translate,
+	},
+};
+
+static struct of_bus *of_match_bus(struct device_node *np)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(of_busses); i ++)
+		if (!of_busses[i].match || of_busses[i].match(np))
+			return &of_busses[i];
+	BUG();
+	return NULL;
+}
+
+static int of_translate_one(struct device_node *parent, struct of_bus *bus,
+			    struct of_bus *pbus, u32 *addr,
+			    int na, int ns, int pna)
+{
+	u32 *ranges;
+	unsigned int rlen;
+	int rone;
+	u64 offset = OF_BAD_ADDR;
+
+	/* Normally, an absence of a "ranges" property means we are
+	 * crossing a non-translatable boundary, and thus the addresses
+	 * below the current not cannot be converted to CPU physical ones.
+	 * Unfortunately, while this is very clear in the spec, it's not
+	 * what Apple understood, and they do have things like /uni-n or
+	 * /ht nodes with no "ranges" property and a lot of perfectly
+	 * useable mapped devices below them. Thus we treat the absence of
+	 * "ranges" as equivalent to an empty "ranges" property which means
+	 * a 1:1 translation at that level. It's up to the caller not to try
+	 * to translate addresses that aren't supposed to be translated in
+	 * the first place. --BenH.
+	 */
+	ranges = (u32 *)get_property(parent, "ranges", &rlen);
+	if (ranges == NULL || rlen == 0) {
+		offset = of_read_addr(addr, na);
+		memset(addr, 0, pna);
+		goto finish;
+	}
+
+	DBG("OF: walking ranges...\n");
+
+	/* Now walk through the ranges */
+	rlen /= 4;
+	rone = na + pna + ns;
+	for (; rlen >= rone; rlen -= rone, ranges += rone) {
+		offset = bus->map(addr, ranges, na, ns, pna);
+		if (offset != OF_BAD_ADDR)
+			break;
+	}
+	if (offset == OF_BAD_ADDR) {
+		DBG("OF: not found !\n");
+		return 1;
+	}
+	memcpy(addr, ranges + na, 4 * pna);
+
+ finish:
+	of_dump_addr("OF: parent translation for:", addr, pna);
+	DBG("OF: with offset: %lx\n", offset);
+
+	/* Translate it into parent bus space */
+	return pbus->translate(addr, offset, pna);
+}
+
+
+/*
+ * Translate an address from the device-tree into a CPU physical address,
+ * this walks up the tree and applies the various bus mappings on the
+ * way.
+ *
+ * Note: We consider that crossing any level with #size-cells == 0 to mean
+ * that translation is impossible (that is we are not dealing with a value
+ * that can be mapped to a cpu physical address). This is not really specified
+ * that way, but this is traditionally the way IBM at least do things
+ */
+u64 of_translate_address(struct device_node *dev, u32 *in_addr)
+{
+	struct device_node *parent = NULL;
+	struct of_bus *bus, *pbus;
+	u32 addr[OF_MAX_ADDR_CELLS];
+	int na, ns, pna, pns;
+	u64 result = OF_BAD_ADDR;
+
+	DBG("OF: ** translation for device %s **\n", dev->full_name);
+
+	/* Increase refcount at current level */
+	of_node_get(dev);
+
+	/* Get parent & match bus type */
+	parent = of_get_parent(dev);
+	if (parent == NULL)
+		goto bail;
+	bus = of_match_bus(parent);
+
+	/* Cound address cells & copy address locally */
+	bus->count_cells(dev, &na, &ns);
+	if (!OF_CHECK_COUNTS(na, ns)) {
+		printk(KERN_ERR "prom_parse: Bad cell count for %s\n",
+		       dev->full_name);
+		goto bail;
+	}
+	memcpy(addr, in_addr, na * 4);
+
+	DBG("OF: bus is %s (na=%d, ns=%d) on %s\n",
+	    bus->name, na, ns, parent->full_name);
+	of_dump_addr("OF: translating address:", addr, na);
+
+	/* Translate */
+	for (;;) {
+		/* Switch to parent bus */
+		of_node_put(dev);
+		dev = parent;
+		parent = of_get_parent(dev);
+
+		/* If root, we have finished */
+		if (parent == NULL) {
+			DBG("OF: reached root node\n");
+			result = of_read_addr(addr, na);
+			break;
+		}
+
+		/* Get new parent bus and counts */
+		pbus = of_match_bus(parent);
+		pbus->count_cells(dev, &pna, &pns);
+		if (!OF_CHECK_COUNTS(pna, pns)) {
+			printk(KERN_ERR "prom_parse: Bad cell count for %s\n",
+			       dev->full_name);
+			break;
+		}
+
+		DBG("OF: parent bus is %s (na=%d, ns=%d) on %s\n",
+		    pbus->name, pna, pns, parent->full_name);
+
+		/* Apply bus translation */
+		if (of_translate_one(dev, bus, pbus, addr, na, ns, pna))
+			break;
+
+		/* Complete the move up one level */
+		na = pna;
+		ns = pns;
+		bus = pbus;
+
+		of_dump_addr("OF: one level translation:", addr, na);
+	}
+ bail:
+	of_node_put(parent);
+	of_node_put(dev);
+
+	return result;
+}
+EXPORT_SYMBOL(of_translate_address);
+
+u32 *of_get_address(struct device_node *dev, int index, u64 *size)
+{
+	u32 *prop;
+	unsigned int psize;
+	struct device_node *parent;
+	struct of_bus *bus;
+	int onesize, i, na, ns;
+
+	/* Get parent & match bus type */
+	parent = of_get_parent(dev);
+	if (parent == NULL)
+		return NULL;
+	bus = of_match_bus(parent);
+	bus->count_cells(dev, &na, &ns);
+	of_node_put(parent);
+	if (!OF_CHECK_COUNTS(na, ns))
+		return NULL;
+
+	/* Get "reg" or "assigned-addresses" property */
+	prop = (u32 *)get_property(dev, bus->addresses, &psize);
+	if (prop == NULL)
+		return NULL;
+	psize /= 4;
+
+	onesize = na + ns;
+	for (i = 0; psize >= onesize; psize -= onesize, prop += onesize, i++)
+		if (i == index) {
+			if (size)
+				*size = of_read_addr(prop + na, ns);
+			return prop;
+		}
+	return NULL;
+}
+EXPORT_SYMBOL(of_get_address);
+
+u32 *of_get_pci_address(struct device_node *dev, int bar_no, u64 *size)
+{
+	u32 *addr;
+	int index;
+
+	for (index = 0; (addr = of_get_address(dev, index, size)) != NULL;
+	     index++) {
+		if ((addr[0] & 0xff) == ((bar_no * 4) + PCI_BASE_ADDRESS_0))
+			return addr;
+	}
+	return NULL;
+}
+EXPORT_SYMBOL(of_get_pci_address);