[PATCH v2 0/4] Align PCI Emul Bridge to PCIe 5.0

[PATCH v2 0/4] Align PCI Emul Bridge to PCIe 5.0

[Jon Derrick]

This set updates pci-bridge-emul for PCIe 4.0 and 5.0. It fixes a few
bit conflicts and comments, and updates a few missing 4.0 and 5.0
definitions. Additionally it eliminates the 'reserved' member by
assuming that ro, rw, and w1c bits are valid and non-conflicting, and
using the inversion of those fields.

v2 changes:
Removed GENMASK/BIT conversion. Existing named fields are left as-is.
Added Rob's acks for unchanged patches 1 & 2

v1: https://lore.kernel.org/linux-pci/20200414203005.5166-1-jonathan.derrick@intel.com/T/#t

Jon Derrick (4):
  PCI: pci-bridge-emul: Fix PCIe bit conflicts
  PCI: pci-bridge-emul: Fix Root Cap/Status comment
  PCI: pci-bridge-emul: Update for PCIe 5.0 r1.0
  PCI: pci-bridge-emul: Eliminate the 'reserved' member

 drivers/pci/pci-bridge-emul.c | 61 ++++++++++++++++++-----------------
 1 file changed, 31 insertions(+), 30 deletions(-)

-- 
2.18.1

[PATCH v2 1/4] PCI: pci-bridge-emul: Fix PCIe bit conflicts

[Jon Derrick]

This patch fixes two bit conflicts in the pci-bridge-emul driver:

1. Bit 3 of Device Status (19 of Device Control) is marked as both
   Write-1-to-Clear and Read-Only. It should be Write-1-to-Clear.
   The Read-Only and Reserved bitmasks are shifted by 1 bit due to this
   error.

2. Bit 12 of Slot Control is marked as both Read-Write and Reserved.
   It should be Read-Write.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
---
 drivers/pci/pci-bridge-emul.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/pci-bridge-emul.c b/drivers/pci/pci-bridge-emul.c
index 4f4f54bc732e..faa414655f33 100644
--- a/drivers/pci/pci-bridge-emul.c
+++ b/drivers/pci/pci-bridge-emul.c
@@ -185,8 +185,8 @@ static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
 		 * RO, the rest is reserved
 		 */
 		.w1c = GENMASK(19, 16),
-		.ro = GENMASK(20, 19),
-		.rsvd = GENMASK(31, 21),
+		.ro = GENMASK(21, 20),
+		.rsvd = GENMASK(31, 22),
 	},
 
 	[PCI_EXP_LNKCAP / 4] = {
@@ -226,7 +226,7 @@ static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
 			PCI_EXP_SLTSTA_CC | PCI_EXP_SLTSTA_DLLSC) << 16,
 		.ro = (PCI_EXP_SLTSTA_MRLSS | PCI_EXP_SLTSTA_PDS |
 		       PCI_EXP_SLTSTA_EIS) << 16,
-		.rsvd = GENMASK(15, 12) | (GENMASK(15, 9) << 16),
+		.rsvd = GENMASK(15, 13) | (GENMASK(15, 9) << 16),
 	},
 
 	[PCI_EXP_RTCTL / 4] = {
-- 
2.18.1

[PATCH v2 2/4] PCI: pci-bridge-emul: Fix Root Cap/Status comment

[Jon Derrick]

The upper 16-bits of Root Control contain the Root Capabilities
register. The code instead describes the Root Status register in the
upper 16-bits, although it uses the correct bit definition for Root
Capabilities, and for Root Status in the next definition.

Fix this comment and add a comment describing the Root Status register.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
---
 drivers/pci/pci-bridge-emul.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/pci-bridge-emul.c b/drivers/pci/pci-bridge-emul.c
index faa414655f33..c00c30ffb198 100644
--- a/drivers/pci/pci-bridge-emul.c
+++ b/drivers/pci/pci-bridge-emul.c
@@ -234,7 +234,7 @@ static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
 		 * Root control has bits [4:0] RW, the rest is
 		 * reserved.
 		 *
-		 * Root status has bit 0 RO, the rest is reserved.
+		 * Root capabilities has bit 0 RO, the rest is reserved.
 		 */
 		.rw = (PCI_EXP_RTCTL_SECEE | PCI_EXP_RTCTL_SENFEE |
 		       PCI_EXP_RTCTL_SEFEE | PCI_EXP_RTCTL_PMEIE |
@@ -244,6 +244,10 @@ static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
 	},
 
 	[PCI_EXP_RTSTA / 4] = {
+		/*
+		 * Root status has bits 17 and [15:0] RO, bit 16 W1C, the rest
+		 * is reserved.
+		 */
 		.ro = GENMASK(15, 0) | PCI_EXP_RTSTA_PENDING,
 		.w1c = PCI_EXP_RTSTA_PME,
 		.rsvd = GENMASK(31, 18),
-- 
2.18.1

[PATCH v2 3/4] PCI: pci-bridge-emul: Update for PCIe 5.0 r1.0

[Jon Derrick]

Add missing bits from PCIe 4.0 and updates for PCIe 5.0 r1.0.

PCIe 4.0:
Device Status bit 6 - W1C - Emergency Power Reduction Detected
Link Control bits 15:14 - RW - DRS Signaling Control
Slot Control bit 13 - RW - Auto Slow Power Limit Disable

PCIe 5.0:
Slot Control bit 14 - RW - In-Band PD Disable

Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
---
 drivers/pci/pci-bridge-emul.c | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/drivers/pci/pci-bridge-emul.c b/drivers/pci/pci-bridge-emul.c
index c00c30ffb198..6b1949995dee 100644
--- a/drivers/pci/pci-bridge-emul.c
+++ b/drivers/pci/pci-bridge-emul.c
@@ -181,12 +181,12 @@ static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
 		.rw = GENMASK(15, 0),
 
 		/*
-		 * Device status register has 4 bits W1C, then 2 bits
-		 * RO, the rest is reserved
+		 * Device status register has bits 6 and [3:0] W1C, [5:4] RO,
+		 * the rest is reserved
 		 */
-		.w1c = GENMASK(19, 16),
-		.ro = GENMASK(21, 20),
-		.rsvd = GENMASK(31, 22),
+		.w1c = (BIT(6) | GENMASK(3, 0)) << 16,
+		.ro = GENMASK(5, 4) << 16,
+		.rsvd = GENMASK(15, 7) << 16,
 	},
 
 	[PCI_EXP_LNKCAP / 4] = {
@@ -197,15 +197,16 @@ static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
 
 	[PCI_EXP_LNKCTL / 4] = {
 		/*
-		 * Link control has bits [1:0] and [11:3] RW, the
-		 * other bits are reserved.
-		 * Link status has bits [13:0] RO, and bits [14:15]
+		 * Link control has bits [15:14], [11:3] and [1:0] RW, the
+		 * rest is reserved.
+		 *
+		 * Link status has bits [13:0] RO, and bits [15:14]
 		 * W1C.
 		 */
-		.rw = GENMASK(11, 3) | GENMASK(1, 0),
+		.rw = GENMASK(15, 14) | GENMASK(11, 3) | GENMASK(1, 0),
 		.ro = GENMASK(13, 0) << 16,
 		.w1c = GENMASK(15, 14) << 16,
-		.rsvd = GENMASK(15, 12) | BIT(2),
+		.rsvd = GENMASK(13, 12) | BIT(2),
 	},
 
 	[PCI_EXP_SLTCAP / 4] = {
@@ -214,19 +215,19 @@ static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
 
 	[PCI_EXP_SLTCTL / 4] = {
 		/*
-		 * Slot control has bits [12:0] RW, the rest is
+		 * Slot control has bits [14:0] RW, the rest is
 		 * reserved.
 		 *
-		 * Slot status has a mix of W1C and RO bits, as well
-		 * as reserved bits.
+		 * Slot status has bits 8 and [4:0] W1C, bits [7:5] RO, the
+		 * rest is reserved.
 		 */
-		.rw = GENMASK(12, 0),
+		.rw = GENMASK(14, 0),
 		.w1c = (PCI_EXP_SLTSTA_ABP | PCI_EXP_SLTSTA_PFD |
 			PCI_EXP_SLTSTA_MRLSC | PCI_EXP_SLTSTA_PDC |
 			PCI_EXP_SLTSTA_CC | PCI_EXP_SLTSTA_DLLSC) << 16,
 		.ro = (PCI_EXP_SLTSTA_MRLSS | PCI_EXP_SLTSTA_PDS |
 		       PCI_EXP_SLTSTA_EIS) << 16,
-		.rsvd = GENMASK(15, 13) | (GENMASK(15, 9) << 16),
+		.rsvd = GENMASK(15) | (GENMASK(15, 9) << 16),
 	},
 
 	[PCI_EXP_RTCTL / 4] = {
-- 
2.18.1

Re: [PATCH v2 3/4] PCI: pci-bridge-emul: Update for PCIe 5.0 r1.0

[Rob Herring]

On Mon, 11 May 2020 12:21:16 -0400, Jon Derrick wrote:
> Add missing bits from PCIe 4.0 and updates for PCIe 5.0 r1.0.
> 
> PCIe 4.0:
> Device Status bit 6 - W1C - Emergency Power Reduction Detected
> Link Control bits 15:14 - RW - DRS Signaling Control
> Slot Control bit 13 - RW - Auto Slow Power Limit Disable
> 
> PCIe 5.0:
> Slot Control bit 14 - RW - In-Band PD Disable
> 
> Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
> ---
>  drivers/pci/pci-bridge-emul.c | 31 ++++++++++++++++---------------
>  1 file changed, 16 insertions(+), 15 deletions(-)
> 

Acked-by: Rob Herring <robh@kernel.org>

[PATCH v2 4/4] PCI: pci-bridge-emul: Eliminate the 'reserved' member

[Jon Derrick]

Per PCIe 5.0 r1.0, Terms and Acronyms, Page 80:

  Reserved register fields must be read only and must return 0 (all 0's
  for multi-bit fields) when read. Reserved encodings for register and
  packet fields must not be used. Any implementation dependence on a
  Reserved field value or encoding will result in an implementation that
  is not PCI Express-compliant.

This patch ensures reads will return 0 for any bit not in the Read-Only,
Read-Write, or Write-1-to-Clear bitmasks.

Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
---
 drivers/pci/pci-bridge-emul.c | 30 +++++++++++++-----------------
 1 file changed, 13 insertions(+), 17 deletions(-)

diff --git a/drivers/pci/pci-bridge-emul.c b/drivers/pci/pci-bridge-emul.c
index 6b1949995dee..ccf26d12ec61 100644
--- a/drivers/pci/pci-bridge-emul.c
+++ b/drivers/pci/pci-bridge-emul.c
@@ -24,6 +24,17 @@
 #define PCI_CAP_PCIE_START	PCI_BRIDGE_CONF_END
 #define PCI_CAP_PCIE_END	(PCI_CAP_PCIE_START + PCI_EXP_SLTSTA2 + 2)
 
+/**
+ * struct pci_bridge_reg_behavior - register bits behaviors
+ * @ro:		Read-Only bits
+ * @rw:		Read-Write bits
+ * @w1c:	Write-1-to-Clear bits
+ *
+ * Reads and Writes will be filtered by specified behavior. All other bits not
+ * declared are assumed 'Reserved' and will return 0 on reads, per PCIe 5.0:
+ * "Reserved register fields must be read only and must return 0 (all 0's for
+ * multi-bit fields) when read".
+ */
 struct pci_bridge_reg_behavior {
 	/* Read-only bits */
 	u32 ro;
@@ -33,9 +44,6 @@ struct pci_bridge_reg_behavior {
 
 	/* Write-1-to-clear bits */
 	u32 w1c;
-
-	/* Reserved bits (hardwired to 0) */
-	u32 rsvd;
 };
 
 static const struct pci_bridge_reg_behavior pci_regs_behavior[] = {
@@ -49,7 +57,6 @@ static const struct pci_bridge_reg_behavior pci_regs_behavior[] = {
 			PCI_COMMAND_FAST_BACK) |
 		       (PCI_STATUS_CAP_LIST | PCI_STATUS_66MHZ |
 			PCI_STATUS_FAST_BACK | PCI_STATUS_DEVSEL_MASK) << 16),
-		.rsvd = GENMASK(15, 10) | ((BIT(6) | GENMASK(3, 0)) << 16),
 		.w1c = PCI_STATUS_ERROR_BITS << 16,
 	},
 	[PCI_CLASS_REVISION / 4] = { .ro = ~0 },
@@ -96,8 +103,6 @@ static const struct pci_bridge_reg_behavior pci_regs_behavior[] = {
 		       GENMASK(11, 8) | GENMASK(3, 0)),
 
 		.w1c = PCI_STATUS_ERROR_BITS << 16,
-
-		.rsvd = ((BIT(6) | GENMASK(4, 0)) << 16),
 	},
 
 	[PCI_MEMORY_BASE / 4] = {
@@ -130,12 +135,10 @@ static const struct pci_bridge_reg_behavior pci_regs_behavior[] = {
 
 	[PCI_CAPABILITY_LIST / 4] = {
 		.ro = GENMASK(7, 0),
-		.rsvd = GENMASK(31, 8),
 	},
 
 	[PCI_ROM_ADDRESS1 / 4] = {
 		.rw = GENMASK(31, 11) | BIT(0),
-		.rsvd = GENMASK(10, 1),
 	},
 
 	/*
@@ -158,8 +161,6 @@ static const struct pci_bridge_reg_behavior pci_regs_behavior[] = {
 		.ro = (GENMASK(15, 8) | ((PCI_BRIDGE_CTL_FAST_BACK) << 16)),
 
 		.w1c = BIT(10) << 16,
-
-		.rsvd = (GENMASK(15, 12) | BIT(4)) << 16,
 	},
 };
 
@@ -186,13 +187,11 @@ static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
 		 */
 		.w1c = (BIT(6) | GENMASK(3, 0)) << 16,
 		.ro = GENMASK(5, 4) << 16,
-		.rsvd = GENMASK(15, 7) << 16,
 	},
 
 	[PCI_EXP_LNKCAP / 4] = {
 		/* All bits are RO, except bit 23 which is reserved */
 		.ro = lower_32_bits(~BIT(23)),
-		.rsvd = BIT(23),
 	},
 
 	[PCI_EXP_LNKCTL / 4] = {
@@ -206,7 +205,6 @@ static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
 		.rw = GENMASK(15, 14) | GENMASK(11, 3) | GENMASK(1, 0),
 		.ro = GENMASK(13, 0) << 16,
 		.w1c = GENMASK(15, 14) << 16,
-		.rsvd = GENMASK(13, 12) | BIT(2),
 	},
 
 	[PCI_EXP_SLTCAP / 4] = {
@@ -227,7 +225,6 @@ static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
 			PCI_EXP_SLTSTA_CC | PCI_EXP_SLTSTA_DLLSC) << 16,
 		.ro = (PCI_EXP_SLTSTA_MRLSS | PCI_EXP_SLTSTA_PDS |
 		       PCI_EXP_SLTSTA_EIS) << 16,
-		.rsvd = GENMASK(15) | (GENMASK(15, 9) << 16),
 	},
 
 	[PCI_EXP_RTCTL / 4] = {
@@ -241,7 +238,6 @@ static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
 		       PCI_EXP_RTCTL_SEFEE | PCI_EXP_RTCTL_PMEIE |
 		       PCI_EXP_RTCTL_CRSSVE),
 		.ro = PCI_EXP_RTCAP_CRSVIS << 16,
-		.rsvd = GENMASK(15, 5) | (GENMASK(15, 1) << 16),
 	},
 
 	[PCI_EXP_RTSTA / 4] = {
@@ -251,7 +247,6 @@ static const struct pci_bridge_reg_behavior pcie_cap_regs_behavior[] = {
 		 */
 		.ro = GENMASK(15, 0) | PCI_EXP_RTSTA_PENDING,
 		.w1c = PCI_EXP_RTSTA_PME,
-		.rsvd = GENMASK(31, 18),
 	},
 };
 
@@ -359,7 +354,8 @@ int pci_bridge_emul_conf_read(struct pci_bridge_emul *bridge, int where,
 	 * Make sure we never return any reserved bit with a value
 	 * different from 0.
 	 */
-	*value &= ~behavior[reg / 4].rsvd;
+	*value &= behavior[reg / 4].ro | behavior[reg / 4].rw |
+		  behavior[reg / 4].w1c;
 
 	if (size == 1)
 		*value = (*value >> (8 * (where & 3))) & 0xff;
-- 
2.18.1

Re: [PATCH v2 4/4] PCI: pci-bridge-emul: Eliminate the 'reserved' member

[Rob Herring]

On Mon, 11 May 2020 12:21:17 -0400, Jon Derrick wrote:
> Per PCIe 5.0 r1.0, Terms and Acronyms, Page 80:
> 
>   Reserved register fields must be read only and must return 0 (all 0's
>   for multi-bit fields) when read. Reserved encodings for register and
>   packet fields must not be used. Any implementation dependence on a
>   Reserved field value or encoding will result in an implementation that
>   is not PCI Express-compliant.
> 
> This patch ensures reads will return 0 for any bit not in the Read-Only,
> Read-Write, or Write-1-to-Clear bitmasks.
> 
> Signed-off-by: Jon Derrick <jonathan.derrick@intel.com>
> ---
>  drivers/pci/pci-bridge-emul.c | 30 +++++++++++++-----------------
>  1 file changed, 13 insertions(+), 17 deletions(-)
> 

Acked-by: Rob Herring <robh@kernel.org>

Re: [PATCH v2 0/4] Align PCI Emul Bridge to PCIe 5.0

[Lorenzo Pieralisi]

On Mon, May 11, 2020 at 12:21:13PM -0400, Jon Derrick wrote:
> This set updates pci-bridge-emul for PCIe 4.0 and 5.0. It fixes a few
> bit conflicts and comments, and updates a few missing 4.0 and 5.0
> definitions. Additionally it eliminates the 'reserved' member by
> assuming that ro, rw, and w1c bits are valid and non-conflicting, and
> using the inversion of those fields.
> 
> v2 changes:
> Removed GENMASK/BIT conversion. Existing named fields are left as-is.
> Added Rob's acks for unchanged patches 1 & 2
> 
> v1: https://lore.kernel.org/linux-pci/20200414203005.5166-1-jonathan.derrick@intel.com/T/#t
> 
> Jon Derrick (4):
>   PCI: pci-bridge-emul: Fix PCIe bit conflicts
>   PCI: pci-bridge-emul: Fix Root Cap/Status comment
>   PCI: pci-bridge-emul: Update for PCIe 5.0 r1.0
>   PCI: pci-bridge-emul: Eliminate the 'reserved' member
> 
>  drivers/pci/pci-bridge-emul.c | 61 ++++++++++++++++++-----------------
>  1 file changed, 31 insertions(+), 30 deletions(-)

Applied to pci/pci-bridge-emul, thanks !

Lorenzo