From: Bjorn Helgaas <bhelgaas@google.com>
Date: Fri, 9 Sep 2022 15:25:00 -0500
Subject: PCI/PTM: Add pci_suspend_ptm() and pci_resume_ptm()
Git-commit: e8bdc5ea481638e0a4fd5639050d2b170417f493
Patch-mainline: 6.1-rc1
References: git-fixes
We disable PTM during suspend because that allows some Root Ports to enter
lower-power PM states, which means we also need to disable PTM for all
downstream devices. Add pci_suspend_ptm() and pci_resume_ptm() for this
purpose.
pci_enable_ptm() and pci_disable_ptm() are for drivers to use to enable or
disable PTM. They use dev->ptm_enabled to keep track of whether PTM should
be enabled.
pci_suspend_ptm() and pci_resume_ptm() are PCI core-internal functions to
temporarily disable PTM during suspend and (depending on dev->ptm_enabled)
re-enable PTM during resume.
Enable/disable/suspend/resume all use internal __pci_enable_ptm() and
__pci_disable_ptm() functions that only update the PTM Control register.
Outline:
pci_enable_ptm(struct pci_dev *dev)
{
__pci_enable_ptm(dev);
dev->ptm_enabled = 1;
pci_ptm_info(dev);
}
pci_disable_ptm(struct pci_dev *dev)
{
if (dev->ptm_enabled) {
__pci_disable_ptm(dev);
dev->ptm_enabled = 0;
}
}
pci_suspend_ptm(struct pci_dev *dev)
{
if (dev->ptm_enabled)
__pci_disable_ptm(dev);
}
pci_resume_ptm(struct pci_dev *dev)
{
if (dev->ptm_enabled)
__pci_enable_ptm(dev);
}
Nothing currently calls pci_resume_ptm(); the suspend path saves the PTM
state before disabling PTM, so the PTM state restore in the resume path
implicitly re-enables it. A future change will use pci_resume_ptm() to fix
some problems with this approach.
Link: https://lore.kernel.org/r/20220909202505.314195-5-helgaas@kernel.org
Tested-by: Rajvi Jingar <rajvi.jingar@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
drivers/pci/pci.c | 4 +--
drivers/pci/pci.h | 6 +++-
drivers/pci/pcie/ptm.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++---
include/linux/pci.h | 2 +
4 files changed, 65 insertions(+), 7 deletions(-)
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2625,7 +2625,7 @@ int pci_prepare_to_sleep(struct pci_dev
* lower-power idle state as a whole.
*/
if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
- pci_disable_ptm(dev);
+ pci_suspend_ptm(dev);
pci_enable_wake(dev, target_state, wakeup);
@@ -2680,7 +2680,7 @@ int pci_finish_runtime_suspend(struct pc
* lower-power idle state as a whole.
*/
if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
- pci_disable_ptm(dev);
+ pci_suspend_ptm(dev);
__pci_enable_wake(dev, target_state, pci_dev_run_wake(dev));
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -545,11 +545,13 @@ static inline int pci_iov_bus_range(stru
#ifdef CONFIG_PCIE_PTM
void pci_save_ptm_state(struct pci_dev *dev);
void pci_restore_ptm_state(struct pci_dev *dev);
-void pci_disable_ptm(struct pci_dev *dev);
+void pci_suspend_ptm(struct pci_dev *dev);
+void pci_resume_ptm(struct pci_dev *dev);
#else
static inline void pci_save_ptm_state(struct pci_dev *dev) { }
static inline void pci_restore_ptm_state(struct pci_dev *dev) { }
-static inline void pci_disable_ptm(struct pci_dev *dev) { }
+static inline void pci_suspend_ptm(struct pci_dev *dev) { }
+static inline void pci_resume_ptm(struct pci_dev *dev) { }
#endif
unsigned long pci_cardbus_resource_alignment(struct resource *);
--- a/drivers/pci/pcie/ptm.c
+++ b/drivers/pci/pcie/ptm.c
@@ -29,7 +29,7 @@ static void pci_ptm_info(struct pci_dev
dev->ptm_root ? " (root)" : "", clock_desc);
}
-void pci_disable_ptm(struct pci_dev *dev)
+static void __pci_disable_ptm(struct pci_dev *dev)
{
int ptm;
u16 ctrl;
@@ -46,6 +46,21 @@ void pci_disable_ptm(struct pci_dev *dev
pci_write_config_word(dev, ptm + PCI_PTM_CTRL, ctrl);
}
+/**
+ * pci_disable_ptm() - Disable Precision Time Measurement
+ * @dev: PCI device
+ *
+ * Disable Precision Time Measurement for @dev.
+ */
+void pci_disable_ptm(struct pci_dev *dev)
+{
+ if (dev->ptm_enabled) {
+ __pci_disable_ptm(dev);
+ dev->ptm_enabled = 0;
+ }
+}
+EXPORT_SYMBOL(pci_disable_ptm);
+
void pci_save_ptm_state(struct pci_dev *dev)
{
int ptm;
@@ -154,7 +169,8 @@ void pci_ptm_init(struct pci_dev *dev)
pci_ptm_info(dev);
}
-int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
+/* Enable PTM in the Control register if possible */
+static int __pci_enable_ptm(struct pci_dev *dev)
{
int pos;
u32 cap, ctrl;
@@ -193,8 +209,29 @@ int pci_enable_ptm(struct pci_dev *dev,
ctrl = PCI_PTM_CTRL_ENABLE;
ctrl |= dev->ptm_granularity << 8;
pci_write_config_dword(dev, pos + PCI_PTM_CTRL, ctrl);
- dev->ptm_enabled = 1;
+ return 0;
+}
+/**
+ * pci_enable_ptm() - Enable Precision Time Measurement
+ * @dev: PCI device
+ * @granularity: pointer to return granularity
+ *
+ * Enable Precision Time Measurement for @dev. If successful and
+ * @granularity is non-NULL, return the Effective Granularity.
+ *
+ * Return: zero if successful, or -EINVAL if @dev lacks a PTM Capability or
+ * is not a PTM Root and lacks an upstream path of PTM-enabled devices.
+ */
+int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
+{
+ int rc;
+
+ rc = __pci_enable_ptm(dev);
+ if (rc)
+ return rc;
+
+ dev->ptm_enabled = 1;
pci_ptm_info(dev);
if (granularity)
@@ -203,6 +240,23 @@ int pci_enable_ptm(struct pci_dev *dev,
}
EXPORT_SYMBOL(pci_enable_ptm);
+/*
+ * Disable PTM, but preserve dev->ptm_enabled so we silently re-enable it on
+ * resume if necessary.
+ */
+void pci_suspend_ptm(struct pci_dev *dev)
+{
+ if (dev->ptm_enabled)
+ __pci_disable_ptm(dev);
+}
+
+/* If PTM was enabled before suspend, re-enable it when resuming */
+void pci_resume_ptm(struct pci_dev *dev)
+{
+ if (dev->ptm_enabled)
+ __pci_enable_ptm(dev);
+}
+
bool pcie_ptm_enabled(struct pci_dev *dev)
{
if (!dev)
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1634,10 +1634,12 @@ bool pci_ats_disabled(void);
#ifdef CONFIG_PCIE_PTM
int pci_enable_ptm(struct pci_dev *dev, u8 *granularity);
+void pci_disable_ptm(struct pci_dev *dev);
bool pcie_ptm_enabled(struct pci_dev *dev);
#else
static inline int pci_enable_ptm(struct pci_dev *dev, u8 *granularity)
{ return -EINVAL; }
+static inline void pci_disable_ptm(struct pci_dev *dev) { }
static inline bool pcie_ptm_enabled(struct pci_dev *dev)
{ return false; }
#endif