Merge branch 'pci/aspm' into next

* pci/aspm:
  PCI/ASPM: Unexport internal ASPM interfaces
  PCI/ASPM: Enable Latency Tolerance Reporting when supported
  PCI/ASPM: Calculate LTR_L1.2_THRESHOLD from device characteristics

drivers/pci/pci.h

@@ -342,6 +342,26 @@ static inline resource_size_t pci_resource_alignment(struct pci_dev *dev,
 
 void pci_enable_acs(struct pci_dev *dev);
 
+#ifdef CONFIG_PCIEASPM
+void pcie_aspm_init_link_state(struct pci_dev *pdev);
+void pcie_aspm_exit_link_state(struct pci_dev *pdev);
+void pcie_aspm_pm_state_change(struct pci_dev *pdev);
+void pcie_aspm_powersave_config_link(struct pci_dev *pdev);
+#else
+static inline void pcie_aspm_init_link_state(struct pci_dev *pdev) { }
+static inline void pcie_aspm_exit_link_state(struct pci_dev *pdev) { }
+static inline void pcie_aspm_pm_state_change(struct pci_dev *pdev) { }
+static inline void pcie_aspm_powersave_config_link(struct pci_dev *pdev) { }
+#endif
+
+#ifdef CONFIG_PCIEASPM_DEBUG
+void pcie_aspm_create_sysfs_dev_files(struct pci_dev *pdev);
+void pcie_aspm_remove_sysfs_dev_files(struct pci_dev *pdev);
+#else
+static inline void pcie_aspm_create_sysfs_dev_files(struct pci_dev *pdev) { }
+static inline void pcie_aspm_remove_sysfs_dev_files(struct pci_dev *pdev) { }
+#endif
+
 #ifdef CONFIG_PCIE_PTM
 void pci_ptm_init(struct pci_dev *dev);
 #else

drivers/pci/pcie/aspm.c

@@ -43,18 +43,6 @@
 #define ASPM_STATE_ALL		(ASPM_STATE_L0S | ASPM_STATE_L1 |	\
 				 ASPM_STATE_L1SS)
 
-/*
- * When L1 substates are enabled, the LTR L1.2 threshold is a timing parameter
- * that decides whether L1.1 or L1.2 is entered (Refer PCIe spec for details).
- * Not sure is there is a way to "calculate" this on the fly, but maybe we
- * could turn it into a parameter in future.  This value has been taken from
- * the following files from Intel's coreboot (which is the only code I found
- * to have used this):
- * https://www.coreboot.org/pipermail/coreboot-gerrit/2015-March/021134.html
- * https://review.coreboot.org/#/c/8832/
- */
-#define LTR_L1_2_THRESHOLD_BITS	((1 << 21) | (1 << 23) | (1 << 30))
-
 struct aspm_latency {
 	u32 l0s;			/* L0s latency (nsec) */
 	u32 l1;				/* L1 latency (nsec) */
@@ -333,6 +321,32 @@ static u32 calc_l1ss_pwron(struct pci_dev *pdev, u32 scale, u32 val)
 	return 0;
 }
 
+static void encode_l12_threshold(u32 threshold_us, u32 *scale, u32 *value)
+{
+	u64 threshold_ns = threshold_us * 1000;
+
+	/* See PCIe r3.1, sec 7.33.3 and sec 6.18 */
+	if (threshold_ns < 32) {
+		*scale = 0;
+		*value = threshold_ns;
+	} else if (threshold_ns < 1024) {
+		*scale = 1;
+		*value = threshold_ns >> 5;
+	} else if (threshold_ns < 32768) {
+		*scale = 2;
+		*value = threshold_ns >> 10;
+	} else if (threshold_ns < 1048576) {
+		*scale = 3;
+		*value = threshold_ns >> 15;
+	} else if (threshold_ns < 33554432) {
+		*scale = 4;
+		*value = threshold_ns >> 20;
+	} else {
+		*scale = 5;
+		*value = threshold_ns >> 25;
+	}
+}
+
 struct aspm_register_info {
 	u32 support:2;
 	u32 enabled:2;
@@ -443,6 +457,7 @@ static void aspm_calc_l1ss_info(struct pcie_link_state *link,
 				struct aspm_register_info *dwreg)
 {
 	u32 val1, val2, scale1, scale2;
+	u32 t_common_mode, t_power_on, l1_2_threshold, scale, value;
 
 	link->l1ss.up_cap_ptr = upreg->l1ss_cap_ptr;
 	link->l1ss.dw_cap_ptr = dwreg->l1ss_cap_ptr;
@@ -454,16 +469,7 @@ static void aspm_calc_l1ss_info(struct pcie_link_state *link,
 	/* Choose the greater of the two Port Common_Mode_Restore_Times */
 	val1 = (upreg->l1ss_cap & PCI_L1SS_CAP_CM_RESTORE_TIME) >> 8;
 	val2 = (dwreg->l1ss_cap & PCI_L1SS_CAP_CM_RESTORE_TIME) >> 8;
-	if (val1 > val2)
-		link->l1ss.ctl1 |= val1 << 8;
-	else
-		link->l1ss.ctl1 |= val2 << 8;
-
-	/*
-	 * We currently use LTR L1.2 threshold to be fixed constant picked from
-	 * Intel's coreboot.
-	 */
-	link->l1ss.ctl1 |= LTR_L1_2_THRESHOLD_BITS;
+	t_common_mode = max(val1, val2);
 
 	/* Choose the greater of the two Port T_POWER_ON times */
 	val1   = (upreg->l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_VALUE) >> 19;
@@ -472,10 +478,27 @@ static void aspm_calc_l1ss_info(struct pcie_link_state *link,
 	scale2 = (dwreg->l1ss_cap & PCI_L1SS_CAP_P_PWR_ON_SCALE) >> 16;
 
 	if (calc_l1ss_pwron(link->pdev, scale1, val1) >
-	    calc_l1ss_pwron(link->downstream, scale2, val2))
+	    calc_l1ss_pwron(link->downstream, scale2, val2)) {
 		link->l1ss.ctl2 |= scale1 | (val1 << 3);
-	else
+		t_power_on = calc_l1ss_pwron(link->pdev, scale1, val1);
+	} else {
 		link->l1ss.ctl2 |= scale2 | (val2 << 3);
+		t_power_on = calc_l1ss_pwron(link->downstream, scale2, val2);
+	}
+
+	/*
+	 * Set LTR_L1.2_THRESHOLD to the time required to transition the
+	 * Link from L0 to L1.2 and back to L0 so we enter L1.2 only if
+	 * downstream devices report (via LTR) that they can tolerate at
+	 * least that much latency.
+	 *
+	 * Based on PCIe r3.1, sec 5.5.3.3.1, Figures 5-16 and 5-17, and
+	 * Table 5-11.  T(POWER_OFF) is at most 2us and T(L1.2) is at
+	 * least 4us.
+	 */
+	l1_2_threshold = 2 + 4 + t_common_mode + t_power_on;
+	encode_l12_threshold(l1_2_threshold, &scale, &value);
+	link->l1ss.ctl1 |= t_common_mode << 8 | scale << 29 | value << 16;
 }
 
 static void pcie_aspm_cap_init(struct pcie_link_state *link, int blacklist)

drivers/pci/probe.c

@@ -1875,6 +1875,38 @@ static void pci_configure_relaxed_ordering(struct pci_dev *dev)
 	}
 }
 
+static void pci_configure_ltr(struct pci_dev *dev)
+{
+#ifdef CONFIG_PCIEASPM
+	u32 cap;
+	struct pci_dev *bridge;
+
+	if (!pci_is_pcie(dev))
+		return;
+
+	pcie_capability_read_dword(dev, PCI_EXP_DEVCAP2, &cap);
+	if (!(cap & PCI_EXP_DEVCAP2_LTR))
+		return;
+
+	/*
+	 * Software must not enable LTR in an Endpoint unless the Root
+	 * Complex and all intermediate Switches indicate support for LTR.
+	 * PCIe r3.1, sec 6.18.
+	 */
+	if (pci_pcie_type(dev) == PCI_EXP_TYPE_ROOT_PORT)
+		dev->ltr_path = 1;
+	else {
+		bridge = pci_upstream_bridge(dev);
+		if (bridge && bridge->ltr_path)
+			dev->ltr_path = 1;
+	}
+
+	if (dev->ltr_path)
+		pcie_capability_set_word(dev, PCI_EXP_DEVCTL2,
+					 PCI_EXP_DEVCTL2_LTR_EN);
+#endif
+}
+
 static void pci_configure_device(struct pci_dev *dev)
 {
 	struct hotplug_params hpp;
@@ -1883,6 +1915,7 @@ static void pci_configure_device(struct pci_dev *dev)
 	pci_configure_mps(dev);
 	pci_configure_extended_tags(dev, NULL);
 	pci_configure_relaxed_ordering(dev);
+	pci_configure_ltr(dev);
 
 	memset(&hpp, 0, sizeof(hpp));
 	ret = pci_get_hp_params(dev, &hpp);

include/linux/pci-aspm.h

@@ -24,43 +24,12 @@
 #define PCIE_LINK_STATE_CLKPM	4
 
 #ifdef CONFIG_PCIEASPM
-void pcie_aspm_init_link_state(struct pci_dev *pdev);
-void pcie_aspm_exit_link_state(struct pci_dev *pdev);
-void pcie_aspm_pm_state_change(struct pci_dev *pdev);
-void pcie_aspm_powersave_config_link(struct pci_dev *pdev);
 void pci_disable_link_state(struct pci_dev *pdev, int state);
 void pci_disable_link_state_locked(struct pci_dev *pdev, int state);
 void pcie_no_aspm(void);
 #else
-static inline void pcie_aspm_init_link_state(struct pci_dev *pdev)
-{
-}
-static inline void pcie_aspm_exit_link_state(struct pci_dev *pdev)
-{
-}
-static inline void pcie_aspm_pm_state_change(struct pci_dev *pdev)
-{
-}
-static inline void pcie_aspm_powersave_config_link(struct pci_dev *pdev)
-{
-}
-static inline void pci_disable_link_state(struct pci_dev *pdev, int state)
-{
-}
-static inline void pcie_no_aspm(void)
-{
-}
+static inline void pci_disable_link_state(struct pci_dev *pdev, int state) { }
+static inline void pcie_no_aspm(void) { }
 #endif
 
-#ifdef CONFIG_PCIEASPM_DEBUG /* this depends on CONFIG_PCIEASPM */
-void pcie_aspm_create_sysfs_dev_files(struct pci_dev *pdev);
-void pcie_aspm_remove_sysfs_dev_files(struct pci_dev *pdev);
-#else
-static inline void pcie_aspm_create_sysfs_dev_files(struct pci_dev *pdev)
-{
-}
-static inline void pcie_aspm_remove_sysfs_dev_files(struct pci_dev *pdev)
-{
-}
-#endif
 #endif /* LINUX_ASPM_H */

include/linux/pci.h

@@ -350,6 +350,8 @@ struct pci_dev {
 
 #ifdef CONFIG_PCIEASPM
 	struct pcie_link_state	*link_state;	/* ASPM link state */
+	unsigned int	ltr_path:1;	/* Latency Tolerance Reporting
+					   supported from root to here */
 #endif
 
 	pci_channel_state_t error_state;	/* current connectivity state */