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PCI: pciehp: Allow exclusive userspace control of indicators

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PCIe hotplug supports optional Attention and Power Indicators, which are
used internally by pciehp.  Users can't control the Power Indicator, but
they can control the Attention Indicator by writing to a sysfs "attention"
file.

The Slot Control register has two bits for each indicator, and the PCIe
spec defines the encodings for each as (Reserved/On/Blinking/Off).  For
sysfs "attention" writes, pciehp_set_attention_status() maps into these
encodings, so the only useful write values are 0 (Off), 1 (On), and 2
(Blinking).

However, some platforms use all four bits for platform-specific indicators,
and they need to allow direct user control of them while preventing pciehp
from using them at all.

Add a "hotplug_user_indicators" flag to the pci_dev structure.  When set,
pciehp does not use either the Attention Indicator or the Power Indicator,
and the low four bits (values 0x0 - 0xf) of sysfs "attention" write values
are written directly to the Attention Indicator Control and Power Indicator
Control fields.

[bhelgaas: changelog, rename flag and accessors to s/attention/indicator/]
Signed-off-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Keith Busch 2016-09-13 10:31:59 -06:00 committed by Bjorn Helgaas
parent 29a654e59f
commit 576243b3f9
4 changed files with 36 additions and 0 deletions
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3
drivers/pci/hotplug/pciehp.h
View File

@ -152,6 +152,9 @@ bool pciehp_check_link_active(struct controller *ctrl);
void pciehp_release_ctrl(struct controller *ctrl);
int pciehp_reset_slot(struct slot *slot, int probe);
int pciehp_set_raw_indicator_status(struct hotplug_slot *h_slot, u8 status);
int pciehp_get_raw_indicator_status(struct hotplug_slot *h_slot, u8 *status);
static inline const char *slot_name(struct slot *slot)
{
return hotplug_slot_name(slot->hotplug_slot);

3
drivers/pci/hotplug/pciehp_core.c
View File

@ -114,6 +114,9 @@ static int init_slot(struct controller *ctrl)
if (ATTN_LED(ctrl)) {
ops->get_attention_status = get_attention_status;
ops->set_attention_status = set_attention_status;
} else if (ctrl->pcie->port->hotplug_user_indicators) {
ops->get_attention_status = pciehp_get_raw_indicator_status;
ops->set_attention_status = pciehp_set_raw_indicator_status;
}
/* register this slot with the hotplug pci core */

27
drivers/pci/hotplug/pciehp_hpc.c
View File

@ -355,6 +355,18 @@ static int pciehp_link_enable(struct controller *ctrl)
return __pciehp_link_set(ctrl, true);
}
int pciehp_get_raw_indicator_status(struct hotplug_slot *hotplug_slot,
u8 *status)
{
struct slot *slot = hotplug_slot->private;
struct pci_dev *pdev = ctrl_dev(slot->ctrl);
u16 slot_ctrl;
pcie_capability_read_word(pdev, PCI_EXP_SLTCTL, &slot_ctrl);
*status = (slot_ctrl & (PCI_EXP_SLTCTL_AIC | PCI_EXP_SLTCTL_PIC)) >> 6;
return 0;
}
void pciehp_get_attention_status(struct slot *slot, u8 *status)
{
struct controller *ctrl = slot->ctrl;
@ -431,6 +443,17 @@ int pciehp_query_power_fault(struct slot *slot)
return !!(slot_status & PCI_EXP_SLTSTA_PFD);
}
int pciehp_set_raw_indicator_status(struct hotplug_slot *hotplug_slot,
u8 status)
{
struct slot *slot = hotplug_slot->private;
struct controller *ctrl = slot->ctrl;
pcie_write_cmd_nowait(ctrl, status << 6,
PCI_EXP_SLTCTL_AIC | PCI_EXP_SLTCTL_PIC);
return 0;
}
void pciehp_set_attention_status(struct slot *slot, u8 value)
{
struct controller *ctrl = slot->ctrl;
@ -814,6 +837,10 @@ struct controller *pcie_init(struct pcie_device *dev)
}
ctrl->pcie = dev;
pcie_capability_read_dword(pdev, PCI_EXP_SLTCAP, &slot_cap);
if (pdev->hotplug_user_indicators)
slot_cap &= ~(PCI_EXP_SLTCAP_AIP | PCI_EXP_SLTCAP_PIP);
ctrl->slot_cap = slot_cap;
mutex_init(&ctrl->ctrl_lock);
init_waitqueue_head(&ctrl->queue);

3
include/linux/pci.h
View File

@ -308,6 +308,9 @@ struct pci_dev {
powered on/off by the
corresponding bridge */
unsigned int ignore_hotplug:1; /* Ignore hotplug events */
unsigned int hotplug_user_indicators:1; /* SlotCtl indicators
controlled exclusively by
user sysfs */
unsigned int d3_delay; /* D3->D0 transition time in ms */
unsigned int d3cold_delay; /* D3cold->D0 transition time in ms */