Commit 72ea91af authored by Heiner Kallweit's avatar Heiner Kallweit Committed by Bjorn Helgaas
Browse files

PCI/ASPM: Add sysfs attributes for controlling ASPM link states 

Add sysfs attributes to Endpoints and other Upstream Ports to control ASPM,
Clock PM, and L1 PM Substates.  The new attributes are:

  /sys/devices/pci*/.../link/clkpm
  /sys/devices/pci*/.../link/l0s_aspm
  /sys/devices/pci*/.../link/l1_aspm
  /sys/devices/pci*/.../link/l1_1_aspm
  /sys/devices/pci*/.../link/l1_2_aspm
  /sys/devices/pci*/.../link/l1_1_pcipm
  /sys/devices/pci*/.../link/l1_2_pcipm

An attribute is only visible if both ends of the Link leading to the device
support the state.  Writing y/1/on to the file enables the state; n/0/off
disables it.

These attributes can be used to tune the power/performance tradeoff for
individual devices.

[bhelgaas: commit log, rename directory to "link"]
Link: https://lore.kernel.org/r/b1c83f8a-9bf6-eac5-82d0-cf5b90128fbf@gmail.com


Signed-off-by: default avatarHeiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent 687aaf38

Documentation/ABI/testing/sysfs-bus-pci

+13 −0
Original line number Diff line number Diff line
@@ -347,3 +347,16 @@ Description: 
		If the device has any Peer-to-Peer memory registered, this

	        file contains a '1' if the memory has been published for

		use outside the driver that owns the device.



What:		/sys/bus/pci/devices/.../link/clkpm

		/sys/bus/pci/devices/.../link/l0s_aspm

		/sys/bus/pci/devices/.../link/l1_aspm

		/sys/bus/pci/devices/.../link/l1_1_aspm

		/sys/bus/pci/devices/.../link/l1_2_aspm

		/sys/bus/pci/devices/.../link/l1_1_pcipm

		/sys/bus/pci/devices/.../link/l1_2_pcipm

Date:		October 2019

Contact:	Heiner Kallweit <hkallweit1@gmail.com>

Description:	If ASPM is supported for an endpoint, these files can be

		used to disable or enable the individual power management

		states. Write y/1/on to enable, n/0/off to disable.

drivers/pci/pci-sysfs.c

+3 −0
Original line number Diff line number Diff line
@@ -1587,6 +1587,9 @@ static const struct attribute_group *pci_dev_attr_groups[] = { 
	&pcie_dev_attr_group,

#ifdef CONFIG_PCIEAER

	&aer_stats_attr_group,

#endif

#ifdef CONFIG_PCIEASPM

	&aspm_ctrl_attr_group,

#endif

	NULL,

};

drivers/pci/pci.h

+4 −0
Original line number Diff line number Diff line
@@ -667,4 +667,8 @@ static inline int pci_acpi_program_hp_params(struct pci_dev *dev) 
}

#endif



#ifdef CONFIG_PCIEASPM

extern const struct attribute_group aspm_ctrl_attr_group;

#endif



#endif /* DRIVERS_PCI_H */

drivers/pci/pcie/aspm.c

+149 −0
Original line number Diff line number Diff line
@@ -899,6 +899,14 @@ static struct pcie_link_state *alloc_pcie_link_state(struct pci_dev *pdev) 
	return link;

}



static void pcie_aspm_update_sysfs_visibility(struct pci_dev *pdev)

{

	struct pci_dev *child;



	list_for_each_entry(child, &pdev->subordinate->devices, bus_list)

		sysfs_update_group(&child->dev.kobj, &aspm_ctrl_attr_group);

}



/*

 * pcie_aspm_init_link_state: Initiate PCI express link state.

 * It is called after the pcie and its children devices are scanned.
@@ -960,6 +968,8 @@ void pcie_aspm_init_link_state(struct pci_dev *pdev) 
		pcie_set_clkpm(link, policy_to_clkpm_state(link));

	}



	pcie_aspm_update_sysfs_visibility(pdev);



unlock:

	mutex_unlock(&aspm_lock);

out:
@@ -1313,6 +1323,145 @@ void pcie_aspm_remove_sysfs_dev_files(struct pci_dev *pdev) 
}

#endif



static ssize_t aspm_attr_show_common(struct device *dev,

				     struct device_attribute *attr,

				     char *buf, u8 state)

{

	struct pci_dev *pdev = to_pci_dev(dev);

	struct pcie_link_state *link = pcie_aspm_get_link(pdev);



	return sprintf(buf, "%d\n", (link->aspm_enabled & state) ? 1 : 0);

}



static ssize_t aspm_attr_store_common(struct device *dev,

				      struct device_attribute *attr,

				      const char *buf, size_t len, u8 state)

{

	struct pci_dev *pdev = to_pci_dev(dev);

	struct pcie_link_state *link = pcie_aspm_get_link(pdev);

	bool state_enable;



	if (strtobool(buf, &state_enable) < 0)

		return -EINVAL;



	down_read(&pci_bus_sem);

	mutex_lock(&aspm_lock);



	if (state_enable) {

		link->aspm_disable &= ~state;

		/* need to enable L1 for substates */

		if (state & ASPM_STATE_L1SS)

			link->aspm_disable &= ~ASPM_STATE_L1;

	} else {

		link->aspm_disable |= state;

	}



	pcie_config_aspm_link(link, policy_to_aspm_state(link));



	mutex_unlock(&aspm_lock);

	up_read(&pci_bus_sem);



	return len;

}



#define ASPM_ATTR(_f, _s)						\

static ssize_t _f##_show(struct device *dev,				\

			 struct device_attribute *attr, char *buf)	\

{ return aspm_attr_show_common(dev, attr, buf, ASPM_STATE_##_s); }	\

									\

static ssize_t _f##_store(struct device *dev,				\

			  struct device_attribute *attr,		\

			  const char *buf, size_t len)			\

{ return aspm_attr_store_common(dev, attr, buf, len, ASPM_STATE_##_s); }



ASPM_ATTR(l0s_aspm, L0S)

ASPM_ATTR(l1_aspm, L1)

ASPM_ATTR(l1_1_aspm, L1_1)

ASPM_ATTR(l1_2_aspm, L1_2)

ASPM_ATTR(l1_1_pcipm, L1_1_PCIPM)

ASPM_ATTR(l1_2_pcipm, L1_2_PCIPM)



static ssize_t clkpm_show(struct device *dev,

			  struct device_attribute *attr, char *buf)

{

	struct pci_dev *pdev = to_pci_dev(dev);

	struct pcie_link_state *link = pcie_aspm_get_link(pdev);



	return sprintf(buf, "%d\n", link->clkpm_enabled);

}



static ssize_t clkpm_store(struct device *dev,

			   struct device_attribute *attr,

			   const char *buf, size_t len)

{

	struct pci_dev *pdev = to_pci_dev(dev);

	struct pcie_link_state *link = pcie_aspm_get_link(pdev);

	bool state_enable;



	if (strtobool(buf, &state_enable) < 0)

		return -EINVAL;



	down_read(&pci_bus_sem);

	mutex_lock(&aspm_lock);



	link->clkpm_disable = !state_enable;

	pcie_set_clkpm(link, policy_to_clkpm_state(link));



	mutex_unlock(&aspm_lock);

	up_read(&pci_bus_sem);



	return len;

}



static DEVICE_ATTR_RW(clkpm);

static DEVICE_ATTR_RW(l0s_aspm);

static DEVICE_ATTR_RW(l1_aspm);

static DEVICE_ATTR_RW(l1_1_aspm);

static DEVICE_ATTR_RW(l1_2_aspm);

static DEVICE_ATTR_RW(l1_1_pcipm);

static DEVICE_ATTR_RW(l1_2_pcipm);



static struct attribute *aspm_ctrl_attrs[] = {

	&dev_attr_clkpm.attr,

	&dev_attr_l0s_aspm.attr,

	&dev_attr_l1_aspm.attr,

	&dev_attr_l1_1_aspm.attr,

	&dev_attr_l1_2_aspm.attr,

	&dev_attr_l1_1_pcipm.attr,

	&dev_attr_l1_2_pcipm.attr,

	NULL

};



static umode_t aspm_ctrl_attrs_are_visible(struct kobject *kobj,

					   struct attribute *a, int n)

{

	struct device *dev = kobj_to_dev(kobj);

	struct pci_dev *pdev = to_pci_dev(dev);

	struct pcie_link_state *link = pcie_aspm_get_link(pdev);

	static const u8 aspm_state_map[] = {

		ASPM_STATE_L0S,

		ASPM_STATE_L1,

		ASPM_STATE_L1_1,

		ASPM_STATE_L1_2,

		ASPM_STATE_L1_1_PCIPM,

		ASPM_STATE_L1_2_PCIPM,

	};



	if (aspm_disabled || !link)

		return 0;



	if (n == 0)

		return link->clkpm_capable ? a->mode : 0;



	return link->aspm_capable & aspm_state_map[n - 1] ? a->mode : 0;

}



const struct attribute_group aspm_ctrl_attr_group = {

	.name = "link",

	.attrs = aspm_ctrl_attrs,

	.is_visible = aspm_ctrl_attrs_are_visible,

};



static int __init pcie_aspm_disable(char *str)

{

	if (!strcmp(str, "off")) {