[PATCH v6 11/42] powerpc/powernv: Trace DMA32 segments consumed by PE

[Gavin Shan]

On P7IOC, the whole DMA32 space is divided evenly to 256MB segments.
Each PE can consume one or multiple DMA32 segments. Current code
doesn't trace the available DMA32 segments and those consumed by
one particular PE. It's conflicting with PCI hotplug.

The patch introduces one bitmap to PHB to trace the available
DMA32 segments for allocation, more fields to "struct pnv_ioda_pe"
to trace the consumed DMA32 segments by the PE, which is going to
be released when the PE is destroyed at PCI unplugging time.

Signed-off-by: Gavin Shan <gwshan at linux.vnet.ibm.com>
---
 arch/powerpc/platforms/powernv/pci-ioda.c | 40 +++++++++++++++++++++++--------
 arch/powerpc/platforms/powernv/pci.h      |  4 +++-
 2 files changed, 33 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index cd22002..57ba8fd 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -1946,6 +1946,7 @@ static void pnv_pci_ioda_setup_dma_pe(struct pnv_phb *phb,
 
 	/* Grab a 32-bit TCE table */
 	pe->dma32_seg = base;
+	pe->dma32_segcount = segs;
 	pe_info(pe, " Setting up 32-bit TCE table at %08x..%08x\n",
 		(base << 28), ((base + segs) << 28) - 1);
 
@@ -2006,8 +2007,13 @@ static void pnv_pci_ioda_setup_dma_pe(struct pnv_phb *phb,
 	return;
  fail:
 	/* XXX Failure: Try to fallback to 64-bit only ? */
-	if (pe->dma32_seg >= 0)
+	if (pe->dma32_seg >= 0) {
+		bitmap_clear(phb->ioda.dma32_segmap,
+			     pe->dma32_seg, pe->dma32_segcount);
 		pe->dma32_seg = -1;
+		pe->dma32_segcount = 0;
+	}
+
 	if (tce_mem)
 		__free_pages(tce_mem, get_order(TCE32_TABLE_SIZE * segs));
 	if (tbl) {
@@ -2443,12 +2449,11 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
 		pnv_ioda_setup_bus_dma(pe, pe->pbus);
 }
 
-static unsigned int pnv_ioda1_setup_dma(struct pnv_phb *phb,
-					struct pnv_ioda_pe *pe,
-					unsigned int base)
+static void pnv_ioda1_setup_dma(struct pnv_phb *phb,
+					struct pnv_ioda_pe *pe)
 {
 	struct pci_controller *hose = phb->hose;
-	unsigned int dma_weight, segs;
+	unsigned int dma_weight, base, segs;
 
 	/* Calculate the PHB's DMA weight */
 	dma_weight = pnv_ioda_phb_dma_weight(phb);
@@ -2461,11 +2466,28 @@ static unsigned int pnv_ioda1_setup_dma(struct pnv_phb *phb,
 	else
 		segs = (pe->dma32_weight *
 			phb->ioda.dma32_segcount) / dma_weight;
+
+	/*
+	 * Allocate DMA32 segments. We might not have enough
+	 * resources available. However we expect at least one
+	 * to be available.
+	 */
+	do {
+		base = bitmap_find_next_zero_area(phb->ioda.dma32_segmap,
+						  phb->ioda.dma32_segcount,
+						  0, segs, 0);
+		if (base < phb->ioda.dma32_segcount) {
+			bitmap_set(phb->ioda.dma32_segmap, base, segs);
+			break;
+		}
+	} while (--segs);
+
+	if (WARN_ON(!segs))
+		return;
+
 	pe_info(pe, "DMA weight %d, assigned %d segments\n",
 		pe->dma32_weight, segs);
 	pnv_pci_ioda_setup_dma_pe(phb, pe, base, segs);
-
-	return segs;
 }
 
 #ifdef CONFIG_PCI_MSI
@@ -2933,20 +2955,18 @@ static void pnv_pci_ioda_setup_DMA(void)
 	struct pci_controller *hose, *tmp;
 	struct pnv_phb *phb;
 	struct pnv_ioda_pe *pe;
-	unsigned int base;
 
 	list_for_each_entry_safe(hose, tmp, &hose_list, list_node) {
 		phb = hose->private_data;
 		pnv_pci_ioda_setup_opal_tce_kill(phb);
 
-		base = 0;
 		list_for_each_entry(pe, &phb->ioda.pe_dma_list, dma_link) {
 			if (!pe->dma32_weight)
 				continue;
 
 			switch (phb->type) {
 			case PNV_PHB_IODA1:
-				base += pnv_ioda1_setup_dma(phb, pe, base);
+				pnv_ioda1_setup_dma(phb, pe);
 				break;
 			case PNV_PHB_IODA2:
 				pnv_pci_ioda2_setup_dma_pe(phb, pe);
diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
index 574fe43..1dc9578 100644
--- a/arch/powerpc/platforms/powernv/pci.h
+++ b/arch/powerpc/platforms/powernv/pci.h
@@ -65,6 +65,7 @@ struct pnv_ioda_pe {
 
 	/* "Base" iommu table, ie, 4K TCEs, 32-bit DMA */
 	int			dma32_seg;
+	int			dma32_segcount;
 	struct iommu_table_group table_group;
 
 	/* 64-bit TCE bypass region */
@@ -153,10 +154,11 @@ struct pnv_phb {
 			unsigned int		io_segsize;
 			unsigned int		io_pci_base;
 
-			/* IO, M32, M64 segment maps */
+			/* IO, M32, M64, DMA32 segment maps */
 			unsigned long		io_segmap[8];
 			unsigned long		m32_segmap[8];
 			unsigned long		m64_segmap[8];
+			unsigned long		dma32_segmap[8];
 
 			/* PE allocation */
 			struct mutex		pe_alloc_mutex;
-- 
2.1.0