diff mbox series

[v2,11/17] PCI: dwc: Simplify in/outbound iATU setup methods

Message ID 20220503214638.1895-12-Sergey.Semin@baikalelectronics.ru (mailing list archive)
State Superseded
Delegated to: Lorenzo Pieralisi
Headers show
Series PCI: dwc: Add dma-ranges/YAML-schema/Baikal-T1 support | expand

Commit Message

Serge Semin May 3, 2022, 9:46 p.m. UTC 
From maintainability and scalability points of view it has been wrong to
use different iATU inbound and outbound regions accessors for the viewport
and unrolled versions of the iATU CSRs mapping. Seeing the particular iATU
region-wise registers layout is almost fully compatible for different
IP-core versions, there were no much points in splitting the code up that
way since it was possible to implement a common windows setup methods for
both viewport and unrolled iATU CSRs spaces. While what we can observe in
the current driver implementation of these methods, is a lot of code
duplication, which consequently worsen the code readability,
maintainability and scalability. Note the current implementation is a bit
more performant than the one suggested in this commit since it implies
having less MMIO accesses. But the gain just doesn't worth having the
denoted difficulties especially seeing the iATU setup methods are mainly
called on the DW PCIe controller and peripheral devices initialization
stage.

Here we suggest to move the iATU viewport and unrolled CSR access
specifics in the dw_pcie_readl_atu() and dw_pcie_writel_atu() method, and
convert the dw_pcie_prog_outbound_atu() and
dw_pcie_prog_{ep_}inbound_atu() functions to being generic instead of
having a different methods for each viewport and unrolled types of iATU
CSRs mapping. Nothing complex really. First of all the dw_pcie_readl_atu()
and dw_pcie_writel_atu() are converted to accept relative iATU CSRs
address together with the iATU region direction (inbound or outbound) and
region index. If DW PCIe controller doesn't have the unrolled iATU CSRs
space, then the accessors will need to activate a iATU viewport based on
the specified direction and index, otherwise a base address for the
corresponding region CSRs will be calculated by means of the
PCIE_ATU_UNROLL_BASE() macro. The CSRs macro have been modified in
accordance with that logic in the pcie-designware.h header file.

The rest of the changes in this commit just concern converting the iATU
in-/out-bound setup methods and iATU regions detection procedure to be
compatible with the new accessors semantics. As a result we've dropped the
no more required dw_pcie_prog_outbound_atu_unroll(),
dw_pcie_prog_inbound_atu_unroll() and dw_pcie_iatu_detect_regions_unroll()
methods.

Note aside with the denoted code improvements, there is an additional
positive side effect of this change. If at some point an atomic iATU
configs setup procedure is required, it will be possible to be done with
no much effort just by adding the synchronization into the
dw_pcie_readl_atu() and dw_pcie_writel_atu() accessors.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>

---

Changelog v2:
- Move the iATU region selection procedure into a helper function (@Rob).
- Simplify the iATU region selection procedure by recalculating the base
  address only if the space is unrolled. The iATU viewport base address
  is saved in the pci->atu_base field from now.
---
 drivers/pci/controller/dwc/pcie-designware.c | 293 ++++++-------------
 drivers/pci/controller/dwc/pcie-designware.h |  48 ++-
 2 files changed, 107 insertions(+), 234 deletions(-)

Comments

Manivannan Sadhasivam May 12, 2022, 2:01 p.m. UTC | #1 
On Wed, May 04, 2022 at 12:46:32AM +0300, Serge Semin wrote:
> From maintainability and scalability points of view it has been wrong to
> use different iATU inbound and outbound regions accessors for the viewport
> and unrolled versions of the iATU CSRs mapping. Seeing the particular iATU
> region-wise registers layout is almost fully compatible for different
> IP-core versions, there were no much points in splitting the code up that
> way since it was possible to implement a common windows setup methods for
> both viewport and unrolled iATU CSRs spaces. While what we can observe in
> the current driver implementation of these methods, is a lot of code
> duplication, which consequently worsen the code readability,
> maintainability and scalability. Note the current implementation is a bit
> more performant than the one suggested in this commit since it implies
> having less MMIO accesses. But the gain just doesn't worth having the
> denoted difficulties especially seeing the iATU setup methods are mainly
> called on the DW PCIe controller and peripheral devices initialization
> stage.
> 
> Here we suggest to move the iATU viewport and unrolled CSR access
> specifics in the dw_pcie_readl_atu() and dw_pcie_writel_atu() method, and
> convert the dw_pcie_prog_outbound_atu() and
> dw_pcie_prog_{ep_}inbound_atu() functions to being generic instead of
> having a different methods for each viewport and unrolled types of iATU
> CSRs mapping. Nothing complex really. First of all the dw_pcie_readl_atu()
> and dw_pcie_writel_atu() are converted to accept relative iATU CSRs
> address together with the iATU region direction (inbound or outbound) and
> region index. If DW PCIe controller doesn't have the unrolled iATU CSRs
> space, then the accessors will need to activate a iATU viewport based on
> the specified direction and index, otherwise a base address for the
> corresponding region CSRs will be calculated by means of the
> PCIE_ATU_UNROLL_BASE() macro. The CSRs macro have been modified in
> accordance with that logic in the pcie-designware.h header file.
> 
> The rest of the changes in this commit just concern converting the iATU
> in-/out-bound setup methods and iATU regions detection procedure to be
> compatible with the new accessors semantics. As a result we've dropped the
> no more required dw_pcie_prog_outbound_atu_unroll(),
> dw_pcie_prog_inbound_atu_unroll() and dw_pcie_iatu_detect_regions_unroll()
> methods.
> 
> Note aside with the denoted code improvements, there is an additional
> positive side effect of this change. If at some point an atomic iATU
> configs setup procedure is required, it will be possible to be done with
> no much effort just by adding the synchronization into the
> dw_pcie_readl_atu() and dw_pcie_writel_atu() accessors.
> 
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> 
> ---
> 
> Changelog v2:
> - Move the iATU region selection procedure into a helper function (@Rob).
> - Simplify the iATU region selection procedure by recalculating the base
>   address only if the space is unrolled. The iATU viewport base address
>   is saved in the pci->atu_base field from now.
> ---
>  drivers/pci/controller/dwc/pcie-designware.c | 293 ++++++-------------
>  drivers/pci/controller/dwc/pcie-designware.h |  48 ++-

In this patch, you also need to fix "pcie-tegra194-acpi.c" driver that makes
use of the removed macros.

Thanks,
Mani
Serge Semin May 12, 2022, 7:22 p.m. UTC | #2 
On Thu, May 12, 2022 at 07:31:24PM +0530, Manivannan Sadhasivam wrote:
> On Wed, May 04, 2022 at 12:46:32AM +0300, Serge Semin wrote:
> > From maintainability and scalability points of view it has been wrong to
> > use different iATU inbound and outbound regions accessors for the viewport
> > and unrolled versions of the iATU CSRs mapping. Seeing the particular iATU
> > region-wise registers layout is almost fully compatible for different
> > IP-core versions, there were no much points in splitting the code up that
> > way since it was possible to implement a common windows setup methods for
> > both viewport and unrolled iATU CSRs spaces. While what we can observe in
> > the current driver implementation of these methods, is a lot of code
> > duplication, which consequently worsen the code readability,
> > maintainability and scalability. Note the current implementation is a bit
> > more performant than the one suggested in this commit since it implies
> > having less MMIO accesses. But the gain just doesn't worth having the
> > denoted difficulties especially seeing the iATU setup methods are mainly
> > called on the DW PCIe controller and peripheral devices initialization
> > stage.
> > 
> > Here we suggest to move the iATU viewport and unrolled CSR access
> > specifics in the dw_pcie_readl_atu() and dw_pcie_writel_atu() method, and
> > convert the dw_pcie_prog_outbound_atu() and
> > dw_pcie_prog_{ep_}inbound_atu() functions to being generic instead of
> > having a different methods for each viewport and unrolled types of iATU
> > CSRs mapping. Nothing complex really. First of all the dw_pcie_readl_atu()
> > and dw_pcie_writel_atu() are converted to accept relative iATU CSRs
> > address together with the iATU region direction (inbound or outbound) and
> > region index. If DW PCIe controller doesn't have the unrolled iATU CSRs
> > space, then the accessors will need to activate a iATU viewport based on
> > the specified direction and index, otherwise a base address for the
> > corresponding region CSRs will be calculated by means of the
> > PCIE_ATU_UNROLL_BASE() macro. The CSRs macro have been modified in
> > accordance with that logic in the pcie-designware.h header file.
> > 
> > The rest of the changes in this commit just concern converting the iATU
> > in-/out-bound setup methods and iATU regions detection procedure to be
> > compatible with the new accessors semantics. As a result we've dropped the
> > no more required dw_pcie_prog_outbound_atu_unroll(),
> > dw_pcie_prog_inbound_atu_unroll() and dw_pcie_iatu_detect_regions_unroll()
> > methods.
> > 
> > Note aside with the denoted code improvements, there is an additional
> > positive side effect of this change. If at some point an atomic iATU
> > configs setup procedure is required, it will be possible to be done with
> > no much effort just by adding the synchronization into the
> > dw_pcie_readl_atu() and dw_pcie_writel_atu() accessors.
> > 
> > Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> > 
> > ---
> > 
> > Changelog v2:
> > - Move the iATU region selection procedure into a helper function (@Rob).
> > - Simplify the iATU region selection procedure by recalculating the base
> >   address only if the space is unrolled. The iATU viewport base address
> >   is saved in the pci->atu_base field from now.
> > ---
> >  drivers/pci/controller/dwc/pcie-designware.c | 293 ++++++-------------
> >  drivers/pci/controller/dwc/pcie-designware.h |  48 ++-
> 

> In this patch, you also need to fix "pcie-tegra194-acpi.c" driver that makes
> use of the removed macros.

Right. I've missed the ACPI part since it isn't available on my
platform. Thanks for noticing that.

-Sergey

> 
> Thanks,
> Mani
> 
> -- 
> மணிவண்ணன் சதாசிவம்
diff mbox series

Patch

diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
index 596c249445ec..0781fa145b3f 100644
--- a/drivers/pci/controller/dwc/pcie-designware.c
+++ b/drivers/pci/controller/dwc/pcie-designware.c
@@ -205,48 +205,64 @@  void dw_pcie_write_dbi2(struct dw_pcie *pci, u32 reg, size_t size, u32 val)
 		dev_err(pci->dev, "write DBI address failed\n");
 }
 
-static u32 dw_pcie_readl_atu(struct dw_pcie *pci, u32 reg)
+static inline void __iomem *dw_pcie_select_atu(struct dw_pcie *pci, u32 dir,
+					       u32 index)
 {
+	void __iomem *base = pci->atu_base;
+
+	if (pci->iatu_unroll_enabled)
+		base += PCIE_ATU_UNROLL_BASE(dir, index);
+	else
+		dw_pcie_writel_dbi(pci, PCIE_ATU_VIEWPORT, dir | index);
+
+	return base;
+}
+
+static u32 dw_pcie_readl_atu(struct dw_pcie *pci, u32 dir, u32 index, u32 reg)
+{
+	void __iomem *base;
 	int ret;
 	u32 val;
 
+	base = dw_pcie_select_atu(pci, dir, index);
+
 	if (pci->ops && pci->ops->read_dbi)
-		return pci->ops->read_dbi(pci, pci->atu_base, reg, 4);
+		return pci->ops->read_dbi(pci, base, reg, 4);
 
-	ret = dw_pcie_read(pci->atu_base + reg, 4, &val);
+	ret = dw_pcie_read(base + reg, 4, &val);
 	if (ret)
 		dev_err(pci->dev, "Read ATU address failed\n");
 
 	return val;
 }
 
-static void dw_pcie_writel_atu(struct dw_pcie *pci, u32 reg, u32 val)
+static void dw_pcie_writel_atu(struct dw_pcie *pci, u32 dir, u32 index,
+			       u32 reg, u32 val)
 {
+	void __iomem *base;
 	int ret;
 
+	base = dw_pcie_select_atu(pci, dir, index);
+
 	if (pci->ops && pci->ops->write_dbi) {
-		pci->ops->write_dbi(pci, pci->atu_base, reg, 4, val);
+		pci->ops->write_dbi(pci, base, reg, 4, val);
 		return;
 	}
 
-	ret = dw_pcie_write(pci->atu_base + reg, 4, val);
+	ret = dw_pcie_write(base + reg, 4, val);
 	if (ret)
 		dev_err(pci->dev, "Write ATU address failed\n");
 }
 
-static u32 dw_pcie_readl_ob_unroll(struct dw_pcie *pci, u32 index, u32 reg)
+static inline u32 dw_pcie_readl_atu_ob(struct dw_pcie *pci, u32 index, u32 reg)
 {
-	u32 offset = PCIE_GET_ATU_OUTB_UNR_REG_OFFSET(index);
-
-	return dw_pcie_readl_atu(pci, offset + reg);
+	return dw_pcie_readl_atu(pci, PCIE_ATU_REGION_DIR_OB, index, reg);
 }
 
-static void dw_pcie_writel_ob_unroll(struct dw_pcie *pci, u32 index, u32 reg,
-				     u32 val)
+static inline void dw_pcie_writel_atu_ob(struct dw_pcie *pci, u32 index, u32 reg,
+					 u32 val)
 {
-	u32 offset = PCIE_GET_ATU_OUTB_UNR_REG_OFFSET(index);
-
-	dw_pcie_writel_atu(pci, offset + reg, val);
+	dw_pcie_writel_atu(pci, PCIE_ATU_REGION_DIR_OB, index, reg, val);
 }
 
 static inline u32 dw_pcie_enable_ecrc(u32 val)
@@ -290,50 +306,6 @@  static inline u32 dw_pcie_enable_ecrc(u32 val)
 	return val | PCIE_ATU_TD;
 }
 
-static void dw_pcie_prog_outbound_atu_unroll(struct dw_pcie *pci, u8 func_no,
-					     int index, int type,
-					     u64 cpu_addr, u64 pci_addr,
-					     u64 size)
-{
-	u32 retries, val;
-	u64 limit_addr = cpu_addr + size - 1;
-
-	dw_pcie_writel_ob_unroll(pci, index, PCIE_ATU_UNR_LOWER_BASE,
-				 lower_32_bits(cpu_addr));
-	dw_pcie_writel_ob_unroll(pci, index, PCIE_ATU_UNR_UPPER_BASE,
-				 upper_32_bits(cpu_addr));
-	dw_pcie_writel_ob_unroll(pci, index, PCIE_ATU_UNR_LOWER_LIMIT,
-				 lower_32_bits(limit_addr));
-	dw_pcie_writel_ob_unroll(pci, index, PCIE_ATU_UNR_UPPER_LIMIT,
-				 upper_32_bits(limit_addr));
-	dw_pcie_writel_ob_unroll(pci, index, PCIE_ATU_UNR_LOWER_TARGET,
-				 lower_32_bits(pci_addr));
-	dw_pcie_writel_ob_unroll(pci, index, PCIE_ATU_UNR_UPPER_TARGET,
-				 upper_32_bits(pci_addr));
-	val = type | PCIE_ATU_FUNC_NUM(func_no);
-	if (upper_32_bits(limit_addr) > upper_32_bits(cpu_addr))
-		val |= PCIE_ATU_INCREASE_REGION_SIZE;
-	if (dw_pcie_ver_is(pci, 490A))
-		val = dw_pcie_enable_ecrc(val);
-	dw_pcie_writel_ob_unroll(pci, index, PCIE_ATU_UNR_REGION_CTRL1, val);
-	dw_pcie_writel_ob_unroll(pci, index, PCIE_ATU_UNR_REGION_CTRL2,
-				 PCIE_ATU_ENABLE);
-
-	/*
-	 * Make sure ATU enable takes effect before any subsequent config
-	 * and I/O accesses.
-	 */
-	for (retries = 0; retries < LINK_WAIT_MAX_IATU_RETRIES; retries++) {
-		val = dw_pcie_readl_ob_unroll(pci, index,
-					      PCIE_ATU_UNR_REGION_CTRL2);
-		if (val & PCIE_ATU_ENABLE)
-			return;
-
-		mdelay(LINK_WAIT_IATU);
-	}
-	dev_err(pci->dev, "Outbound iATU is not being enabled\n");
-}
-
 static void __dw_pcie_prog_outbound_atu(struct dw_pcie *pci, u8 func_no,
 					int index, int type, u64 cpu_addr,
 					u64 pci_addr, u64 size)
@@ -344,49 +316,46 @@  static void __dw_pcie_prog_outbound_atu(struct dw_pcie *pci, u8 func_no,
 	if (pci->ops && pci->ops->cpu_addr_fixup)
 		cpu_addr = pci->ops->cpu_addr_fixup(pci, cpu_addr);
 
-	if (pci->iatu_unroll_enabled) {
-		dw_pcie_prog_outbound_atu_unroll(pci, func_no, index, type,
-						 cpu_addr, pci_addr, size);
-		return;
-	}
-
 	limit_addr = cpu_addr + size - 1;
 
-	dw_pcie_writel_dbi(pci, PCIE_ATU_VIEWPORT,
-			   PCIE_ATU_REGION_DIR_OB | index);
-	dw_pcie_writel_dbi(pci, PCIE_ATU_LOWER_BASE,
-			   lower_32_bits(cpu_addr));
-	dw_pcie_writel_dbi(pci, PCIE_ATU_UPPER_BASE,
-			   upper_32_bits(cpu_addr));
-	dw_pcie_writel_dbi(pci, PCIE_ATU_LIMIT,
-			   lower_32_bits(limit_addr));
+	dw_pcie_writel_atu_ob(pci, index, PCIE_ATU_LOWER_BASE,
+			      lower_32_bits(cpu_addr));
+	dw_pcie_writel_atu_ob(pci, index, PCIE_ATU_UPPER_BASE,
+			      upper_32_bits(cpu_addr));
+
+	dw_pcie_writel_atu_ob(pci, index, PCIE_ATU_LIMIT,
+			      lower_32_bits(limit_addr));
 	if (dw_pcie_ver_is_ge(pci, 460A))
-		dw_pcie_writel_dbi(pci, PCIE_ATU_UPPER_LIMIT,
-				   upper_32_bits(limit_addr));
-	dw_pcie_writel_dbi(pci, PCIE_ATU_LOWER_TARGET,
-			   lower_32_bits(pci_addr));
-	dw_pcie_writel_dbi(pci, PCIE_ATU_UPPER_TARGET,
-			   upper_32_bits(pci_addr));
+		dw_pcie_writel_atu_ob(pci, index, PCIE_ATU_UPPER_LIMIT,
+				      upper_32_bits(limit_addr));
+
+	dw_pcie_writel_atu_ob(pci, index, PCIE_ATU_LOWER_TARGET,
+			      lower_32_bits(pci_addr));
+	dw_pcie_writel_atu_ob(pci, index, PCIE_ATU_UPPER_TARGET,
+			      upper_32_bits(pci_addr));
+
 	val = type | PCIE_ATU_FUNC_NUM(func_no);
 	if (upper_32_bits(limit_addr) > upper_32_bits(cpu_addr) &&
 	    dw_pcie_ver_is_ge(pci, 460A))
 		val |= PCIE_ATU_INCREASE_REGION_SIZE;
 	if (dw_pcie_ver_is(pci, 490A))
 		val = dw_pcie_enable_ecrc(val);
-	dw_pcie_writel_dbi(pci, PCIE_ATU_CR1, val);
-	dw_pcie_writel_dbi(pci, PCIE_ATU_CR2, PCIE_ATU_ENABLE);
+	dw_pcie_writel_atu_ob(pci, index, PCIE_ATU_REGION_CTRL1, val);
+
+	dw_pcie_writel_atu_ob(pci, index, PCIE_ATU_REGION_CTRL2, PCIE_ATU_ENABLE);
 
 	/*
 	 * Make sure ATU enable takes effect before any subsequent config
 	 * and I/O accesses.
 	 */
 	for (retries = 0; retries < LINK_WAIT_MAX_IATU_RETRIES; retries++) {
-		val = dw_pcie_readl_dbi(pci, PCIE_ATU_CR2);
+		val = dw_pcie_readl_atu_ob(pci, index, PCIE_ATU_REGION_CTRL2);
 		if (val & PCIE_ATU_ENABLE)
 			return;
 
 		mdelay(LINK_WAIT_IATU);
 	}
+
 	dev_err(pci->dev, "Outbound iATU is not being enabled\n");
 }
 
@@ -405,54 +374,15 @@  void dw_pcie_prog_ep_outbound_atu(struct dw_pcie *pci, u8 func_no, int index,
 				    cpu_addr, pci_addr, size);
 }
 
-static u32 dw_pcie_readl_ib_unroll(struct dw_pcie *pci, u32 index, u32 reg)
-{
-	u32 offset = PCIE_GET_ATU_INB_UNR_REG_OFFSET(index);
-
-	return dw_pcie_readl_atu(pci, offset + reg);
-}
-
-static void dw_pcie_writel_ib_unroll(struct dw_pcie *pci, u32 index, u32 reg,
-				     u32 val)
+static inline u32 dw_pcie_readl_atu_ib(struct dw_pcie *pci, u32 index, u32 reg)
 {
-	u32 offset = PCIE_GET_ATU_INB_UNR_REG_OFFSET(index);
-
-	dw_pcie_writel_atu(pci, offset + reg, val);
+	return dw_pcie_readl_atu(pci, PCIE_ATU_REGION_DIR_IB, index, reg);
 }
 
-static int dw_pcie_prog_inbound_atu_unroll(struct dw_pcie *pci, u8 func_no,
-					   int index, int type,
-					   u64 cpu_addr, u8 bar)
+static inline void dw_pcie_writel_atu_ib(struct dw_pcie *pci, u32 index, u32 reg,
+					 u32 val)
 {
-	u32 retries, val;
-
-	dw_pcie_writel_ib_unroll(pci, index, PCIE_ATU_UNR_LOWER_TARGET,
-				 lower_32_bits(cpu_addr));
-	dw_pcie_writel_ib_unroll(pci, index, PCIE_ATU_UNR_UPPER_TARGET,
-				 upper_32_bits(cpu_addr));
-
-	dw_pcie_writel_ib_unroll(pci, index, PCIE_ATU_UNR_REGION_CTRL1, type |
-				 PCIE_ATU_FUNC_NUM(func_no));
-	dw_pcie_writel_ib_unroll(pci, index, PCIE_ATU_UNR_REGION_CTRL2,
-				 PCIE_ATU_FUNC_NUM_MATCH_EN |
-				 PCIE_ATU_ENABLE |
-				 PCIE_ATU_BAR_MODE_ENABLE | (bar << 8));
-
-	/*
-	 * Make sure ATU enable takes effect before any subsequent config
-	 * and I/O accesses.
-	 */
-	for (retries = 0; retries < LINK_WAIT_MAX_IATU_RETRIES; retries++) {
-		val = dw_pcie_readl_ib_unroll(pci, index,
-					      PCIE_ATU_UNR_REGION_CTRL2);
-		if (val & PCIE_ATU_ENABLE)
-			return 0;
-
-		mdelay(LINK_WAIT_IATU);
-	}
-	dev_err(pci->dev, "Inbound iATU is not being enabled\n");
-
-	return -EBUSY;
+	dw_pcie_writel_atu(pci, PCIE_ATU_REGION_DIR_IB, index, reg, val);
 }
 
 int dw_pcie_prog_inbound_atu(struct dw_pcie *pci, u8 func_no, int index,
@@ -460,51 +390,37 @@  int dw_pcie_prog_inbound_atu(struct dw_pcie *pci, u8 func_no, int index,
 {
 	u32 retries, val;
 
-	if (pci->iatu_unroll_enabled)
-		return dw_pcie_prog_inbound_atu_unroll(pci, func_no, index, type,
-						       cpu_addr, bar);
+	dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_LOWER_TARGET,
+			      lower_32_bits(cpu_addr));
+	dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_UPPER_TARGET,
+			      upper_32_bits(cpu_addr));
 
-	dw_pcie_writel_dbi(pci, PCIE_ATU_VIEWPORT, PCIE_ATU_REGION_DIR_IB |
-			   index);
-	dw_pcie_writel_dbi(pci, PCIE_ATU_LOWER_TARGET, lower_32_bits(cpu_addr));
-	dw_pcie_writel_dbi(pci, PCIE_ATU_UPPER_TARGET, upper_32_bits(cpu_addr));
-
-	dw_pcie_writel_dbi(pci, PCIE_ATU_CR1, type |
-			   PCIE_ATU_FUNC_NUM(func_no));
-	dw_pcie_writel_dbi(pci, PCIE_ATU_CR2, PCIE_ATU_ENABLE |
-			   PCIE_ATU_FUNC_NUM_MATCH_EN |
-			   PCIE_ATU_BAR_MODE_ENABLE | (bar << 8));
+	dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_REGION_CTRL1, type |
+			      PCIE_ATU_FUNC_NUM(func_no));
+	dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_REGION_CTRL2,
+			      PCIE_ATU_ENABLE | PCIE_ATU_FUNC_NUM_MATCH_EN |
+			      PCIE_ATU_BAR_MODE_ENABLE | (bar << 8));
 
 	/*
 	 * Make sure ATU enable takes effect before any subsequent config
 	 * and I/O accesses.
 	 */
 	for (retries = 0; retries < LINK_WAIT_MAX_IATU_RETRIES; retries++) {
-		val = dw_pcie_readl_dbi(pci, PCIE_ATU_CR2);
+		val = dw_pcie_readl_atu_ib(pci, index, PCIE_ATU_REGION_CTRL2);
 		if (val & PCIE_ATU_ENABLE)
 			return 0;
 
 		mdelay(LINK_WAIT_IATU);
 	}
+
 	dev_err(pci->dev, "Inbound iATU is not being enabled\n");
 
-	return -EBUSY;
+	return -ETIMEDOUT;
 }
 
 void dw_pcie_disable_atu(struct dw_pcie *pci, u32 dir, int index)
 {
-	if (pci->iatu_unroll_enabled) {
-		if (dir == PCIE_ATU_REGION_DIR_IB) {
-			dw_pcie_writel_ib_unroll(pci, index, PCIE_ATU_UNR_REGION_CTRL2,
-						 ~(u32)PCIE_ATU_ENABLE);
-		} else {
-			dw_pcie_writel_ob_unroll(pci, index, PCIE_ATU_UNR_REGION_CTRL2,
-						 ~(u32)PCIE_ATU_ENABLE);
-		}
-	} else {
-		dw_pcie_writel_dbi(pci, PCIE_ATU_VIEWPORT, dir | index);
-		dw_pcie_writel_dbi(pci, PCIE_ATU_CR2, ~(u32)PCIE_ATU_ENABLE);
-	}
+	dw_pcie_writel_atu(pci, dir, index, PCIE_ATU_REGION_CTRL2, 0);
 }
 
 int dw_pcie_wait_for_link(struct dw_pcie *pci)
@@ -606,63 +522,29 @@  static bool dw_pcie_iatu_unroll_enabled(struct dw_pcie *pci)
 	return false;
 }
 
-static void dw_pcie_iatu_detect_regions_unroll(struct dw_pcie *pci)
-{
-	int max_region, i, ob = 0, ib = 0;
-	u32 val;
-
-	max_region = min((int)pci->atu_size / 512, 256);
-
-	for (i = 0; i < max_region; i++) {
-		dw_pcie_writel_ob_unroll(pci, i, PCIE_ATU_UNR_LOWER_TARGET,
-					0x11110000);
-
-		val = dw_pcie_readl_ob_unroll(pci, i, PCIE_ATU_UNR_LOWER_TARGET);
-		if (val == 0x11110000)
-			ob++;
-		else
-			break;
-	}
-
-	for (i = 0; i < max_region; i++) {
-		dw_pcie_writel_ib_unroll(pci, i, PCIE_ATU_UNR_LOWER_TARGET,
-					0x11110000);
-
-		val = dw_pcie_readl_ib_unroll(pci, i, PCIE_ATU_UNR_LOWER_TARGET);
-		if (val == 0x11110000)
-			ib++;
-		else
-			break;
-	}
-	pci->num_ib_windows = ib;
-	pci->num_ob_windows = ob;
-}
-
 static void dw_pcie_iatu_detect_regions(struct dw_pcie *pci)
 {
-	int max_region, i, ob = 0, ib = 0;
+	int max_region, ob, ib;
 	u32 val;
 
-	dw_pcie_writel_dbi(pci, PCIE_ATU_VIEWPORT, 0xFF);
-	max_region = dw_pcie_readl_dbi(pci, PCIE_ATU_VIEWPORT) + 1;
+	if (pci->iatu_unroll_enabled) {
+		max_region = min((int)pci->atu_size / 512, 256);
+	} else {
+		dw_pcie_writel_dbi(pci, PCIE_ATU_VIEWPORT, 0xFF);
+		max_region = dw_pcie_readl_dbi(pci, PCIE_ATU_VIEWPORT) + 1;
+	}
 
-	for (i = 0; i < max_region; i++) {
-		dw_pcie_writel_dbi(pci, PCIE_ATU_VIEWPORT, PCIE_ATU_REGION_DIR_OB | i);
-		dw_pcie_writel_dbi(pci, PCIE_ATU_LOWER_TARGET, 0x11110000);
-		val = dw_pcie_readl_dbi(pci, PCIE_ATU_LOWER_TARGET);
-		if (val == 0x11110000)
-			ob++;
-		else
+	for (ob = 0; ob < max_region; ob++) {
+		dw_pcie_writel_atu_ob(pci, ob, PCIE_ATU_LOWER_TARGET, 0x11110000);
+		val = dw_pcie_readl_atu_ob(pci, ob, PCIE_ATU_LOWER_TARGET);
+		if (val != 0x11110000)
 			break;
 	}
 
-	for (i = 0; i < max_region; i++) {
-		dw_pcie_writel_dbi(pci, PCIE_ATU_VIEWPORT, PCIE_ATU_REGION_DIR_IB | i);
-		dw_pcie_writel_dbi(pci, PCIE_ATU_LOWER_TARGET, 0x11110000);
-		val = dw_pcie_readl_dbi(pci, PCIE_ATU_LOWER_TARGET);
-		if (val == 0x11110000)
-			ib++;
-		else
+	for (ib = 0; ib < max_region; ib++) {
+		dw_pcie_writel_atu_ib(pci, ib, PCIE_ATU_LOWER_TARGET, 0x11110000);
+		val = dw_pcie_readl_atu_ib(pci, ib, PCIE_ATU_LOWER_TARGET);
+		if (val != 0x11110000)
 			break;
 	}
 
@@ -691,12 +573,13 @@  void dw_pcie_iatu_detect(struct dw_pcie *pci)
 		if (!pci->atu_size)
 			/* Pick a minimal default, enough for 8 in and 8 out windows */
 			pci->atu_size = SZ_4K;
-
-		dw_pcie_iatu_detect_regions_unroll(pci);
 	} else {
-		dw_pcie_iatu_detect_regions(pci);
+		pci->atu_base = pci->dbi_base + PCIE_ATU_VIEWPORT_BASE;
+		pci->atu_size = PCIE_ATU_VIEWPORT_SIZE;
 	}
 
+	dw_pcie_iatu_detect_regions(pci);
+
 	dev_info(pci->dev, "iATU unroll: %s\n", pci->iatu_unroll_enabled ?
 		"enabled" : "disabled");
 
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 0bda68f8ffdb..f5b793caabff 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -103,10 +103,21 @@ 
 #define PCIE_VERSION_NUMBER		0x8F8
 #define PCIE_VERSION_TYPE		0x8FC
 
+/*
+ * iATU inbound and outbound windows CSRs. Before the IP-core v4.80a each
+ * iATU region CSRs had been indirectly accessible by means of the dedicated
+ * viewport selector. The iATU/eDMA CSRs space was re-designed in DWC PCIe
+ * v4.80a in a way so the viewport was unrolled into the directly accessible
+ * iATU/eDMA CSRs space.
+ */
 #define PCIE_ATU_VIEWPORT		0x900
 #define PCIE_ATU_REGION_DIR_IB		BIT(31)
 #define PCIE_ATU_REGION_DIR_OB		0
-#define PCIE_ATU_CR1			0x904
+#define PCIE_ATU_VIEWPORT_BASE		0x904
+#define PCIE_ATU_UNROLL_BASE(dir, index) \
+	(((index) << 9) | ((dir == PCIE_ATU_REGION_DIR_IB) ? BIT(8) : 0))
+#define PCIE_ATU_VIEWPORT_SIZE		0x2C
+#define PCIE_ATU_REGION_CTRL1		0x000
 #define PCIE_ATU_INCREASE_REGION_SIZE	BIT(13)
 #define PCIE_ATU_TYPE_MEM		0x0
 #define PCIE_ATU_TYPE_IO		0x2
@@ -114,19 +125,19 @@ 
 #define PCIE_ATU_TYPE_CFG1		0x5
 #define PCIE_ATU_TD			BIT(8)
 #define PCIE_ATU_FUNC_NUM(pf)           ((pf) << 20)
-#define PCIE_ATU_CR2			0x908
+#define PCIE_ATU_REGION_CTRL2		0x004
 #define PCIE_ATU_ENABLE			BIT(31)
 #define PCIE_ATU_BAR_MODE_ENABLE	BIT(30)
 #define PCIE_ATU_FUNC_NUM_MATCH_EN      BIT(19)
-#define PCIE_ATU_LOWER_BASE		0x90C
-#define PCIE_ATU_UPPER_BASE		0x910
-#define PCIE_ATU_LIMIT			0x914
-#define PCIE_ATU_LOWER_TARGET		0x918
+#define PCIE_ATU_LOWER_BASE		0x008
+#define PCIE_ATU_UPPER_BASE		0x00C
+#define PCIE_ATU_LIMIT			0x010
+#define PCIE_ATU_LOWER_TARGET		0x014
 #define PCIE_ATU_BUS(x)			FIELD_PREP(GENMASK(31, 24), x)
 #define PCIE_ATU_DEV(x)			FIELD_PREP(GENMASK(23, 19), x)
 #define PCIE_ATU_FUNC(x)		FIELD_PREP(GENMASK(18, 16), x)
-#define PCIE_ATU_UPPER_TARGET		0x91C
-#define PCIE_ATU_UPPER_LIMIT		0x924
+#define PCIE_ATU_UPPER_TARGET		0x018
+#define PCIE_ATU_UPPER_LIMIT		0x020
 
 #define PCIE_MISC_CONTROL_1_OFF		0x8BC
 #define PCIE_DBI_RO_WR_EN		BIT(0)
@@ -143,19 +154,6 @@ 
 
 #define PCIE_PL_CHK_REG_ERR_ADDR			0xB28
 
-/*
- * iATU Unroll-specific register definitions
- * From 4.80 core version the address translation will be made by unroll
- */
-#define PCIE_ATU_UNR_REGION_CTRL1	0x00
-#define PCIE_ATU_UNR_REGION_CTRL2	0x04
-#define PCIE_ATU_UNR_LOWER_BASE		0x08
-#define PCIE_ATU_UNR_UPPER_BASE		0x0C
-#define PCIE_ATU_UNR_LOWER_LIMIT	0x10
-#define PCIE_ATU_UNR_LOWER_TARGET	0x14
-#define PCIE_ATU_UNR_UPPER_TARGET	0x18
-#define PCIE_ATU_UNR_UPPER_LIMIT	0x20
-
 /*
  * The default address offset between dbi_base and atu_base. Root controller
  * drivers are not required to initialize atu_base if the offset matches this
@@ -164,13 +162,6 @@ 
  */
 #define DEFAULT_DBI_ATU_OFFSET (0x3 << 20)
 
-/* Register address builder */
-#define PCIE_GET_ATU_OUTB_UNR_REG_OFFSET(region) \
-		((region) << 9)
-
-#define PCIE_GET_ATU_INB_UNR_REG_OFFSET(region) \
-		(((region) << 9) | BIT(8))
-
 #define MAX_MSI_IRQS			256
 #define MAX_MSI_IRQS_PER_CTRL		32
 #define MAX_MSI_CTRLS			(MAX_MSI_IRQS / MAX_MSI_IRQS_PER_CTRL)
@@ -276,7 +267,6 @@  struct dw_pcie {
 	struct device		*dev;
 	void __iomem		*dbi_base;
 	void __iomem		*dbi_base2;
-	/* Used when iatu_unroll_enabled is true */
 	void __iomem		*atu_base;
 	size_t			atu_size;
 	u32			num_ib_windows;