[PATCH v6 19/42] powerpc/powernv: Reserve PE# for root bus

[Gavin Shan]

pcibios_setup_bridge() is normally called to update PCI bridge
windows. It allocates PE for PCI buses. However it is not called
on a root bus which does not have an upstream bridge.

This reserves PE# for a root bus in advance. This will be used in
the subsequent patch to do setup.

Signed-off-by: Gavin Shan <gwshan at linux.vnet.ibm.com>
---
 arch/powerpc/platforms/powernv/pci-ioda.c | 30 +++++++++++++++++++++++++++++-
 arch/powerpc/platforms/powernv/pci.h      |  1 +
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 1c950e8..8aa6ab8 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -236,6 +236,13 @@ static int pnv_ioda1_init_m64(struct pnv_phb *phb)
 		pr_warn("  Cannot strip M64 segment for reserved PE#%d\n",
 			phb->ioda.reserved_pe_idx);
 
+	/* Strip off the M64 segment corresponding to the PE#
+	 * for PCI root bus, which is last supported PE# or
+	 * (reserved PE# - 1).
+	 */
+	if (phb->ioda.root_pe_idx != IODA_INVALID_PE)
+		r->end -= phb->ioda.m64_segsize;
+
 	return 0;
 
 fail:
@@ -293,6 +300,13 @@ static int pnv_ioda2_init_m64(struct pnv_phb *phb)
 		pr_warn("  Cannot strip M64 segment for reserved PE#%d\n",
 			phb->ioda.reserved_pe_idx);
 
+	/* Strip off the M64 segment corresponding to the PE#
+	 * for PCI root bus, which is last supported PE# or
+	 * (reserved PE# - 1).
+	 */
+	if (phb->ioda.root_pe_idx != IODA_INVALID_PE)
+		r->end -= phb->ioda.m64_segsize;
+
 	return 0;
 
 fail:
@@ -3237,7 +3251,21 @@ static void __init pnv_pci_init_ioda_phb(struct device_node *np,
 	aux = memblock_virt_alloc(size, 0);
 	phb->ioda.pe_alloc = aux;
 	phb->ioda.pe_array = aux + pemap_off;
-	set_bit(phb->ioda.reserved_pe_idx, phb->ioda.pe_alloc);
+
+	/* Choose number of PE for root bus, which shouldn't consume
+	 * any M64 resource. So we avoid picking low-end PE#, which
+	 * is usually bound with M64 resources closely.
+	 */
+	pnv_ioda_reserve_pe(phb, phb->ioda.reserved_pe_idx);
+	if (phb->ioda.reserved_pe_idx == 0) {
+		phb->ioda.root_pe_idx = phb->ioda.total_pe_num - 1;
+		pnv_ioda_reserve_pe(phb, phb->ioda.root_pe_idx);
+	} else if (phb->ioda.reserved_pe_idx == (phb->ioda.total_pe_num - 1)) {
+		phb->ioda.root_pe_idx = phb->ioda.reserved_pe_idx - 1;
+		pnv_ioda_reserve_pe(phb, phb->ioda.root_pe_idx);
+	} else {
+		phb->ioda.root_pe_idx = IODA_INVALID_PE;
+	}
 
 	INIT_LIST_HEAD(&phb->ioda.pe_dma_list);
 	INIT_LIST_HEAD(&phb->ioda.pe_list);
diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
index fc899cd..e93a489 100644
--- a/arch/powerpc/platforms/powernv/pci.h
+++ b/arch/powerpc/platforms/powernv/pci.h
@@ -135,6 +135,7 @@ struct pnv_phb {
 		struct {
 			/* Global bridge info */
 			unsigned int		total_pe_num;
+			unsigned int		root_pe_idx;
 			unsigned int		reserved_pe_idx;
 
 			/* 32-bit MMIO window */
-- 
2.1.0