[PATCH v2 12/17] PCI: dwc: Add iATU regions size detection procedure

[Serge Semin <Sergey.Semin@baikalelectronics.ru>]

Depending on the DWC PCIe RC/EP/DM IP-core configuration parameters the
controllers can be equipped not only with various number of inbound and
outbound iATU windows, but with varied regions settings like alignment
(which is also the minimum window size), minimum and maximum sizes. So to
speak if internal ATU is enabled for the denoted IP-cores then the former
settings will be defined by the CX_ATU_MIN_REGION_SIZE parameter while the
later one will be determined by the CX_ATU_MAX_REGION_SIZE configuration
parameter. Anyway having these parameters used in the driver will help to
verify whether the requested inbound or outbound memory mappings can be
fully created. Currently the driver doesn't perform any corresponding
checking.

Note 1. The extended iATU regions have been supported since DWC PCIe
v4.60a. There is no need in testing the upper limit register availability
for the older cores.

Note 2. The regions alignment is determined with using the fls() method
since the lower four bits of the ATU Limit register can be occupied with
the Circular Buffer Increment setting, which can be initialized with
zeros.

The (dma-)ranges verification will be added a bit later in one of the next
commits.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
---
 drivers/pci/controller/dwc/pcie-designware.c | 33 +++++++++++++++++---
 drivers/pci/controller/dwc/pcie-designware.h |  2 ++
 2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 0781fa145b3f..1cc5e3b2fa6d 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -8,9 +8,11 @@
  * Author: Jingoo Han <jg1.han@samsung.com>
  */
 
+#include <linux/bitops.h>
 #include <linux/delay.h>
 #include <linux/of.h>
 #include <linux/of_platform.h>
+#include <linux/sizes.h>
 #include <linux/types.h>
 
 #include "../../pci.h"
@@ -525,7 +527,8 @@ static bool dw_pcie_iatu_unroll_enabled(struct dw_pcie *pci)
 static void dw_pcie_iatu_detect_regions(struct dw_pcie *pci)
 {
 	int max_region, ob, ib;
-	u32 val;
+	u32 val, min, dir;
+	u64 max;
 
 	if (pci->iatu_unroll_enabled) {
 		max_region = min((int)pci->atu_size / 512, 256);
@@ -548,8 +551,29 @@ static void dw_pcie_iatu_detect_regions(struct dw_pcie *pci)
 			break;
 	}
 
-	pci->num_ib_windows = ib;
+	if (ob) {
+		dir = PCIE_ATU_REGION_DIR_OB;
+	} else if (ib) {
+		dir = PCIE_ATU_REGION_DIR_IB;
+	} else {
+		dev_err(pci->dev, "No iATU regions found\n");
+		return;
+	}
+
+	dw_pcie_writel_atu(pci, dir, 0, PCIE_ATU_LIMIT, 0x0);
+	min = dw_pcie_readl_atu(pci, dir, 0, PCIE_ATU_LIMIT);
+
+	if (dw_pcie_ver_is_ge(pci, 460A)) {
+		dw_pcie_writel_atu(pci, dir, 0, PCIE_ATU_UPPER_LIMIT, 0xFFFFFFFF);
+		max = dw_pcie_readl_atu(pci, dir, 0, PCIE_ATU_UPPER_LIMIT);
+	} else {
+		max = 0;
+	}
+
 	pci->num_ob_windows = ob;
+	pci->num_ib_windows = ib;
+	pci->region_align = 1 << fls(min);
+	pci->region_limit = (max << 32) | (SZ_4G - 1);
 }
 
 void dw_pcie_iatu_detect(struct dw_pcie *pci)
@@ -583,8 +607,9 @@ void dw_pcie_iatu_detect(struct dw_pcie *pci)
 	dev_info(pci->dev, "iATU unroll: %s\n", pci->iatu_unroll_enabled ?
 		"enabled" : "disabled");
 
-	dev_info(pci->dev, "Detected iATU regions: %u outbound, %u inbound\n",
-		 pci->num_ob_windows, pci->num_ib_windows);
+	dev_info(pci->dev, "iATU regions: %u ob, %u ib, align %uK, limit %lluG\n",
+		 pci->num_ob_windows, pci->num_ib_windows,
+		 pci->region_align / SZ_1K, (pci->region_limit + 1) / SZ_1G);
 }
 
 void dw_pcie_setup(struct dw_pcie *pci)
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index f5b793caabff..faf42f2b2ff3 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -271,6 +271,8 @@ struct dw_pcie {
 	size_t			atu_size;
 	u32			num_ib_windows;
 	u32			num_ob_windows;
+	u32			region_align;
+	u64			region_limit;
 	struct pcie_port	pp;
 	struct dw_pcie_ep	ep;
 	const struct dw_pcie_ops *ops;
-- 
2.35.1