This patch adds detection of broken 64-bit mode LL/SC on Cobalt units.
With this patch my Qube2700 boots a 64-bit build fine. The later units
have some problems with the Tulip driver.
P.
--
Index: linux/arch/mips/kernel/cpu-probe.c
===================================================================
--- linux.orig/arch/mips/kernel/cpu-probe.c 2005-04-11 23:19:17.000000000 +0100
+++ linux/arch/mips/kernel/cpu-probe.c 2005-04-11 23:35:06.000000000 +0100
@@ -131,6 +131,58 @@
check_wait();
}
+#ifdef CONFIG_MIPS64
+
+/*
+ * On RM5230/5231 all accesses to XKPHYS by LL(D) are forced
+ * to be uncached, bits 61-59 of the address are ignored.
+ *
+ * Apparently fixed on RM5230A/5231A.
+ */
+static inline int check_lld(void)
+{
+ unsigned long flags, value, match, phys, *addr;
+
+ printk("Checking for lld bug... ");
+
+ /* hope the stack is in the low 512MB */
+ phys = CPHYSADDR((unsigned long) &value);
+
+ /* write value to memory */
+ value = 0xfedcba9876543210;
+ addr = (unsigned long *) PHYS_TO_XKPHYS(K_CALG_UNCACHED, phys);
+ *addr = value;
+
+ /* stop spurious flushes */
+ local_irq_save(flags);
+
+ /* flip cached value */
+ value = ~value;
+
+ /* read value, supposedly from cache */
+ addr = (unsigned long *) PHYS_TO_XKPHYS(K_CALG_NONCOHERENT, phys);
+ asm volatile("lld %0, %1" : "=r" (match) : "m" (*addr));
+
+ local_irq_restore(flags);
+
+ match ^= value;
+
+ switch ((long) match) {
+ case 0:
+ printk("no.\n");
+ break;
+ case -1:
+ printk("yes.\n");
+ break;
+ default:
+ printk("yikes yes! (%lx/%lx@%p)\nPlease report to <linux-mips@xxxxxxxxxxxxxx>.", value, match, &value);
+ }
+
+ return !match;
+}
+
+#endif
+
/*
* Probe whether cpu has config register by trying to play with
* alternate cache bit and see whether it matters.
@@ -347,7 +399,11 @@
c->cputype = CPU_NEVADA;
c->isa_level = MIPS_CPU_ISA_IV;
c->options = R4K_OPTS | MIPS_CPU_FPU | MIPS_CPU_32FPR |
- MIPS_CPU_DIVEC | MIPS_CPU_LLSC;
+ MIPS_CPU_DIVEC;
+#ifdef CONFIG_MIPS64
+ if (check_lld())
+#endif
+ c->options |= MIPS_CPU_LLSC;
c->tlbsize = 48;
break;
case PRID_IMP_R6000:
Index: linux/include/asm-mips/addrspace.h
===================================================================
--- linux.orig/include/asm-mips/addrspace.h 2005-04-11 23:19:17.000000000 +0100
+++ linux/include/asm-mips/addrspace.h 2005-04-11 23:19:20.000000000 +0100
@@ -120,7 +120,7 @@
#define PHYS_TO_XKSEG_UNCACHED(p) PHYS_TO_XKPHYS(K_CALG_UNCACHED,(p))
#define PHYS_TO_XKSEG_CACHED(p) PHYS_TO_XKPHYS(K_CALG_COH_SHAREABLE,(p))
#define XKPHYS_TO_PHYS(p) ((p) & TO_PHYS_MASK)
-#define PHYS_TO_XKPHYS(cm,a) (0x8000000000000000 | ((cm)<<59) | (a))
+#define PHYS_TO_XKPHYS(cm,a) (0x8000000000000000 | ((unsigned long)(cm)<<59) | (a))
#if defined (CONFIG_CPU_R4300) \
|| defined (CONFIG_CPU_R4X00) \
