[POWERPC] Derive ebc ranges property from EBC registers

In the device tree for Ebony, the 'ranges' property in the node for
the EBC bridge shows the mappings from the chip select / address lines
actually used for the EBC peripherals into the address space of the
OPB.  At present, these mappings are hardcoded in ebony.dts for the
mappings set up by the OpenBIOS firmware when it configures the EBC
bridge.

This replaces the hardcoded mappings with code in the zImage to
read the EBC configuration registers and create an appropriate ranges
property based on them.  This should make the zImage and kernel more
robust to changes in firmware configuration.  In particular, some of
the Ebony's DIP switches can change the effective address of the Flash
and other peripherals in OPB space.  With this patch, the kernel will
be able to cope with at least some of the possible variations.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

5 files changed, 71 insertions, 5 deletions

diff --git a/arch/powerpc/boot/44x.c b/arch/powerpc/boot/44x.c
index bc3f570ff9ba..9f64e840bef6 100644
--- a/arch/powerpc/boot/44x.c
+++ b/arch/powerpc/boot/44x.c
@@ -54,3 +54,32 @@ void ibm44x_dbcr_reset(void)
                 );
 
 }
+
+/* Read 4xx EBC bus bridge registers to get mappings of the peripheral
+ * banks into the OPB address space */
+void ibm4xx_fixup_ebc_ranges(const char *ebc)
+{
+        void *devp;
+        u32 bxcr;
+        u32 ranges[EBC_NUM_BANKS*4];
+        u32 *p = ranges;
+        int i;
+
+        for (i = 0; i < EBC_NUM_BANKS; i++) {
+                mtdcr(DCRN_EBC0_CFGADDR, EBC_BXCR(i));
+                bxcr = mfdcr(DCRN_EBC0_CFGDATA);
+
+                if ((bxcr & EBC_BXCR_BU) != EBC_BXCR_BU_OFF) {
+                        *p++ = i;
+                        *p++ = 0;
+                        *p++ = bxcr & EBC_BXCR_BAS;
+                        *p++ = EBC_BXCR_BANK_SIZE(bxcr);
+                }
+        }
+
+        devp = finddevice(ebc);
+        if (! devp)
+                fatal("Couldn't locate EBC node %s\n\r", ebc);
+
+        setprop(devp, "ranges", ranges, (p - ranges) * sizeof(u32));
+}
diff --git a/arch/powerpc/boot/44x.h b/arch/powerpc/boot/44x.h
index 0da4abf390ad..577982c9a3cd 100644
--- a/arch/powerpc/boot/44x.h
+++ b/arch/powerpc/boot/44x.h
@@ -11,6 +11,7 @@
 #define _PPC_BOOT_44X_H_
 
 void ibm44x_fixup_memsize(void);
+void ibm4xx_fixup_ebc_ranges(const char *ebc);
 
 void ibm44x_dbcr_reset(void);
 void ebony_init(void *mac0, void *mac1);
diff --git a/arch/powerpc/boot/dcr.h b/arch/powerpc/boot/dcr.h
index 877bc97b1e97..14b44aa96fea 100644
--- a/arch/powerpc/boot/dcr.h
+++ b/arch/powerpc/boot/dcr.h
@@ -26,6 +26,43 @@ static const unsigned long sdram_bxcr[] = { SDRAM0_B0CR, SDRAM0_B1CR, SDRAM0_B2C
 #define                 SDRAM_CONFIG_BANK_SIZE(reg)     \
         (0x00400000 << ((reg & SDRAM_CONFIG_SIZE_MASK) >> 17))
 
+/* 440GP External Bus Controller (EBC) */
+#define DCRN_EBC0_CFGADDR                               0x012
+#define DCRN_EBC0_CFGDATA                               0x013
+#define   EBC_NUM_BANKS                                   8
+#define   EBC_B0CR                                        0x00
+#define   EBC_B1CR                                        0x01
+#define   EBC_B2CR                                        0x02
+#define   EBC_B3CR                                        0x03
+#define   EBC_B4CR                                        0x04
+#define   EBC_B5CR                                        0x05
+#define   EBC_B6CR                                        0x06
+#define   EBC_B7CR                                        0x07
+#define   EBC_BXCR(n)                                     (n)
+#define     EBC_BXCR_BAS                                    0xfff00000
+#define     EBC_BXCR_BS                                     0x000e0000
+#define     EBC_BXCR_BANK_SIZE(reg) \
+        (0x100000 << (((reg) & EBC_BXCR_BS) >> 17))
+#define     EBC_BXCR_BU                                     0x00018000
+#define       EBC_BXCR_BU_OFF                                 0x00000000
+#define       EBC_BXCR_BU_RO                                  0x00008000
+#define       EBC_BXCR_BU_WO                                  0x00010000
+#define       EBC_BXCR_BU_RW                                  0x00018000
+#define     EBC_BXCR_BW                                     0x00006000
+#define   EBC_B0AP                                        0x10
+#define   EBC_B1AP                                        0x11
+#define   EBC_B2AP                                        0x12
+#define   EBC_B3AP                                        0x13
+#define   EBC_B4AP                                        0x14
+#define   EBC_B5AP                                        0x15
+#define   EBC_B6AP                                        0x16
+#define   EBC_B7AP                                        0x17
+#define   EBC_BXAP(n)                                     (0x10+(n))
+#define   EBC_BEAR                                        0x20
+#define   EBC_BESR                                        0x21
+#define   EBC_CFG                                         0x23
+#define   EBC_CID                                         0x24
+
 /* 440GP Clock, PM, chip control */
 #define DCRN_CPC0_SR                                    0x0b0
 #define DCRN_CPC0_ER                                    0x0b1
diff --git a/arch/powerpc/boot/dts/ebony.dts b/arch/powerpc/boot/dts/ebony.dts
index 0ec02f4726b5..586a2fc13c63 100644
--- a/arch/powerpc/boot/dts/ebony.dts
+++ b/arch/powerpc/boot/dts/ebony.dts
@@ -135,11 +135,9 @@
                                 #address-cells = <2>;
                                 #size-cells = <1>;
                                 clock-frequency = <0>; // Filled in by zImage
-                                ranges = <0 00000000 fff00000 100000
-                                          1 00000000 48000000 100000
-                                          2 00000000 ff800000 400000
-                                          3 00000000 48200000 100000
-                                          7 00000000 48300000 100000>;
+                                // ranges property is supplied by zImage
+                                // based on firmware's configuration of the
+                                // EBC bridge
                                 interrupts = <5 4>;
                                 interrupt-parent = <&UIC1>;
 
diff --git a/arch/powerpc/boot/ebony.c b/arch/powerpc/boot/ebony.c
index 634985802006..75daedafd0a4 100644
--- a/arch/powerpc/boot/ebony.c
+++ b/arch/powerpc/boot/ebony.c
@@ -100,6 +100,7 @@ static void ebony_fixups(void)
         ibm440gp_fixup_clocks(sysclk, 6 * 1843200);
         ibm44x_fixup_memsize();
         dt_fixup_mac_addresses(ebony_mac0, ebony_mac1);
+        ibm4xx_fixup_ebc_ranges("/plb/opb/ebc");
 }
 
 void ebony_init(void *mac0, void *mac1)