[PATCH] ppc64: implement iommu=off for pseries

From: Anton Blanchard <anton@samba.org>

Implement iommu=off for pseries.  We limit memory to 2GB as pmac does,
however the default for < 2GB remains iommu=on unlike pmac.

arch/ppc64/kernel/chrp_setup.c

@@ -206,15 +206,17 @@ void __init fwnmi_init(void)
 		fwnmi_active = 1;
 }
 
-
 /* Early initialization.  Relocation is on but do not reference unbolted pages */
 void __init pSeries_init_early(void)
 {
-#ifdef CONFIG_PPC_PSERIES	/* This ifdef should go away */
 	void *comport;
 
 	hpte_init_pSeries();
-	tce_init_pSeries();
+
+	if (ppc64_iommu_off)
+		pci_dma_init_direct();
+	else
+		tce_init_pSeries();
 
 #ifdef CONFIG_SMP
 	smp_init_pSeries();
@@ -227,7 +229,6 @@ void __init pSeries_init_early(void)
 	ppc_md.udbg_putc = udbg_putc;
 	ppc_md.udbg_getc = udbg_getc;
 	ppc_md.udbg_getc_poll = udbg_getc_poll;
-#endif
 }
 
 void __init

arch/ppc64/kernel/pSeries_pci.c

@@ -699,7 +699,8 @@ void __init pSeries_final_fixup(void)
 	phbs_fixup_io();
 	chrp_request_regions();
 	pci_fix_bus_sysdata();
-	iommu_setup_pSeries();
+	if (!ppc64_iommu_off)
+		iommu_setup_pSeries();
 }
 
 /*********************************************************************** 

arch/ppc64/kernel/prom.c

@@ -525,25 +525,16 @@ prom_initialize_naca(unsigned long mem)
 	return mem;
 }
 
-#ifdef CONFIG_PMAC_DART
-static int dart_force_on;
-#endif
+static int iommu_force_on;
+int ppc64_iommu_off;
 
-static unsigned long __init
-prom_initialize_lmb(unsigned long mem)
+static void early_cmdline_parse(void)
 {
-	phandle node;
-	char type[64];
-        unsigned long i, offset = reloc_offset();
-	struct prom_t *_prom = PTRRELOC(&prom);
-        struct systemcfg *_systemcfg = RELOC(systemcfg);
-	union lmb_reg_property reg;
-	unsigned long lmb_base, lmb_size;
-	unsigned long num_regs, bytes_per_reg = (_prom->encode_phys_size*2)/8;
-	int nodart = 0;
-
-#ifdef CONFIG_PMAC_DART
+	unsigned long offset = reloc_offset();
 	char *opt;
+#ifndef CONFIG_PMAC_DART
+	struct systemcfg *_systemcfg = RELOC(systemcfg);
+#endif
 
 	opt = strstr(RELOC(cmd_line), RELOC("iommu="));
 	if (opt) {
@@ -554,16 +545,30 @@ prom_initialize_lmb(unsigned long mem)
 		while (*opt && *opt == ' ')
 			opt++;
 		if (!strncmp(opt, RELOC("off"), 3))
-			nodart = 1;
+			RELOC(ppc64_iommu_off) = 1;
 		else if (!strncmp(opt, RELOC("force"), 5))
-			RELOC(dart_force_on) = 1;
+			RELOC(iommu_force_on) = 1;
 	}
-#else
-	nodart = 1;
-#endif /* CONFIG_PMAC_DART */
 
-	if (nodart)
+#ifndef CONFIG_PMAC_DART
+	if (_systemcfg->platform == PLATFORM_POWERMAC) {
+		RELOC(ppc64_iommu_off) = 1;
 		prom_print(RELOC("DART disabled on PowerMac !\n"));
+	}
+#endif
+}
+
+static unsigned long __init
+prom_initialize_lmb(unsigned long mem)
+{
+	phandle node;
+	char type[64];
+        unsigned long i, offset = reloc_offset();
+	struct prom_t *_prom = PTRRELOC(&prom);
+        struct systemcfg *_systemcfg = RELOC(systemcfg);
+	union lmb_reg_property reg;
+	unsigned long lmb_base, lmb_size;
+	unsigned long num_regs, bytes_per_reg = (_prom->encode_phys_size*2)/8;
 
 	lmb_init();
 
@@ -589,11 +594,6 @@ prom_initialize_lmb(unsigned long mem)
 				lmb_base = ((unsigned long)reg.addrPM[i].address_hi) << 32;
 				lmb_base |= (unsigned long)reg.addrPM[i].address_lo;
 				lmb_size = reg.addrPM[i].size;
-				if (nodart && lmb_base > 0x80000000ull) {
-					prom_print(RELOC("Skipping memory above 2Gb for "
-							 "now, DART support disabled\n"));
-					continue;
-				}
 			} else if (_prom->encode_phys_size == 32) {
 				lmb_base = reg.addr32[i].address;
 				lmb_size = reg.addr32[i].size;
@@ -602,7 +602,16 @@ prom_initialize_lmb(unsigned long mem)
 				lmb_size = reg.addr64[i].size;
 			}
 
-			if ( lmb_add(lmb_base, lmb_size) < 0 )
+			/* We limit memory to 2GB if the IOMMU is off */
+			if (RELOC(ppc64_iommu_off)) {
+				if (lmb_base >= 0x80000000UL)
+					continue;
+
+				if ((lmb_base + lmb_size) > 0x80000000UL)
+					lmb_size = 0x80000000UL - lmb_base;
+			}
+
+			if (lmb_add(lmb_base, lmb_size) < 0)
 				prom_print(RELOC("Too many LMB's, discarding this one...\n"));
 		}
 
@@ -780,7 +789,7 @@ void prom_initialize_dart_table(void)
 	/* Only reserve DART space if machine has more than 2GB of RAM
 	 * or if requested with iommu=on on cmdline.
 	 */
-	if (lmb_end_of_DRAM() <= 0x80000000ull && !RELOC(dart_force_on))
+	if (lmb_end_of_DRAM() <= 0x80000000ull && !RELOC(iommu_force_on))
 		return;
 
 	/* 512 pages is max DART tablesize. */
@@ -811,6 +820,9 @@ prom_initialize_tce_table(void)
 	struct of_tce_table *prom_tce_table = RELOC(of_tce_table);
 	unsigned long tce_entry, *tce_entryp;
 
+	if (RELOC(ppc64_iommu_off))
+		return;
+
 #ifdef DEBUG_PROM
 	prom_print(RELOC("starting prom_initialize_tce_table\n"));
 #endif
@@ -1583,6 +1595,8 @@ prom_init(unsigned long r3, unsigned long r4, unsigned long pp,
 			strlcpy(RELOC(cmd_line), p, sizeof(cmd_line));
 	}
 
+	early_cmdline_parse();
+
 	mem = prom_initialize_lmb(mem);
 
 	mem = prom_bi_rec_reserve(mem);

include/asm-ppc64/iommu.h

@@ -152,4 +152,6 @@ extern void tce_init_iSeries(void);
 extern void pci_iommu_init(void);
 extern void pci_dma_init_direct(void);
 
+extern int ppc64_iommu_off;
+
 #endif