PCI/ASPM: Add support for L1 Substates from 4.11

* 6 upstream patches are included, described below.
PCI/ASPM: Add L1 substate capability structure register definitions
PCI/ASPM: Add support for L1 substates
PCI/ASPM: Read and set up L1 substate capabilities
PCI/ASPM: Calculate and save the L1.2 timing parameters
PCI/ASPM: Configure L1 substate settings
PCI/ASPM: Add comment about L1 substate latency

Merge commit into pci.git: 8f417ca9ebfa8701a41db64f5ed9cbb01b8e4219
--

PCI/ASPM: Add L1 substate capability structure register definitions

Add L1 substate capability structure register definitions for use in
subsequent patches.  See the PCIe r3.1 spec, sec 7.33.

[bhelgaas: add PCIe spec reference]
Signed-off-by: Rajat Jain <rajatja@google.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/ASPM: Add support for L1 substates

Add support for ASPM L1 substates.  For details about L1 substates, see the
PCIe r3.1 spec, which includes the ECN below in secs 5.5 and 7.33.

Add macros for the 4 new L1 substates, and add a new ASPM "POWER_SUPERSAVE"
policy that can be used to enable L1 substates on a system if desired.  The
new policy is in a sense, a superset of the existing POWERSAVE policy.  The
4 policies are now:

  DEFAULT: Reads and uses whatever ASPM states BIOS enabled
  PERFORMANCE: Everything except L0 disabled.
  POWERSAVE: L0s and L1 enabled (but not L1 substates)
  POWER_SUPERSAVE: L0s + L1 + L1 substates also enabled

[bhelgaas: add PCIe r3.1 spec reference]
Link: https://pcisig.com/sites/default/files/specification_documents/ECN_L1_PM_Substates_with_CLKREQ_31_May_2013_Rev10a.pdf
Signed-off-by: Rajat Jain <rajatja@google.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/ASPM: Read and set up L1 substate capabilities

The PCIe spec (r3.1, sec 7.33) says the L1 PM Substates Capability may be
implemented only in function 0.

Read the L1 substate capability structures of upstream and downstream
components of the link and set it up in the device structure.

[bhelgaas: add specific spec reference]
Signed-off-by: Rajat Jain <rajatja@google.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/ASPM: Calculate and save the L1.2 timing parameters

Calculate and save the timing parameters that need to be programmed if we
need to enable L1.2 substates later.

We use the same logic (and a constant value for 1 of the parameters) as
used by Intel's coreboot:

  https://www.coreboot.org/pipermail/coreboot-gerrit/2015-March/021134.html
  https://review.coreboot.org/#/c/8832/

Signed-off-by: Rajat Jain <rajatja@google.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/ASPM: Configure L1 substate settings

Configure the L1 substate settings on the upstream and downstream devices,
while taking care of the rules dictated by the PCIe spec.

[bhelgaas: drop "inline"]
Signed-off-by: Rajat Jain <rajatja@google.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

PCI/ASPM: Add comment about L1 substate latency

Since the exit latencies for L1 substates are not advertised by a device,
it is not clear in spec how to do a L1 substate exit latency check.  We
assume that the L1 exit latencies advertised by a device include L1
substate latencies (and hence do not do any check).  If that is not true,
we should do some sort of check here.

(I'm not clear about what that check should like currently. I'd be glad to
take up any suggestions).

Change-Id: Ic63503da580412535e3ca0dc5caed7c30c270f84
Signed-off-by: Rajat Jain <rajatja@google.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/pci/pcie/Kconfig      |   8 +
 drivers/pci/pcie/aspm.c       | 330 ++++++++++++++++++++++++++++++++++++++----
 include/uapi/linux/pci_regs.h |  16 ++
 3 files changed, 325 insertions(+), 29 deletions(-)

1 files changed, 16 insertions, 0 deletions

diff --git a/include/uapi/linux/pci_regs.h b/include/uapi/linux/pci_regs.h
index ecc8e01c5616..b67cfd8d3705 100644
--- a/include/uapi/linux/pci_regs.h
+++ b/include/uapi/linux/pci_regs.h
@@ -674,6 +674,7 @@
 #define PCI_EXT_CAP_ID_PMUX	0x1A	/* Protocol Multiplexing */
 #define PCI_EXT_CAP_ID_PASID	0x1B	/* Process Address Space ID */
 #define PCI_EXT_CAP_ID_DPC	0x1D	/* Downstream Port Containment */
+#define PCI_EXT_CAP_ID_L1SS	0x1E	/* L1 PM Substates */
 #define PCI_EXT_CAP_ID_PTM	0x1F	/* Precision Time Measurement */
 #define PCI_EXT_CAP_ID_MAX	PCI_EXT_CAP_ID_PTM
 
@@ -977,4 +978,19 @@
 #define  PCI_PTM_CTRL_ENABLE		0x00000001  /* PTM enable */
 #define  PCI_PTM_CTRL_ROOT		0x00000002  /* Root select */
 
+/* L1 PM Substates */
+#define PCI_L1SS_CAP		    4	/* capability register */
+#define  PCI_L1SS_CAP_PCIPM_L1_2	 1	/* PCI PM L1.2 Support */
+#define  PCI_L1SS_CAP_PCIPM_L1_1	 2	/* PCI PM L1.1 Support */
+#define  PCI_L1SS_CAP_ASPM_L1_2		 4	/* ASPM L1.2 Support */
+#define  PCI_L1SS_CAP_ASPM_L1_1		 8	/* ASPM L1.1 Support */
+#define  PCI_L1SS_CAP_L1_PM_SS		16	/* L1 PM Substates Support */
+#define PCI_L1SS_CTL1		    8	/* Control Register 1 */
+#define  PCI_L1SS_CTL1_PCIPM_L1_2	1	/* PCI PM L1.2 Enable */
+#define  PCI_L1SS_CTL1_PCIPM_L1_1	2	/* PCI PM L1.1 Support */
+#define  PCI_L1SS_CTL1_ASPM_L1_2	4	/* ASPM L1.2 Support */
+#define  PCI_L1SS_CTL1_ASPM_L1_1	8	/* ASPM L1.1 Support */
+#define  PCI_L1SS_CTL1_L1SS_MASK	0x0000000F
+#define PCI_L1SS_CTL2		    0xC	/* Control Register 2 */
+
 #endif /* LINUX_PCI_REGS_H */