iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

PCI: of: Add of_pci_preserve_config() for per-host bridge support

Browse Source 
Add of_pci_preserve_config() to look for the "linux,pci-probe-only"
property under a specified node.  If it's not found there, look under
"of_chosen" in addition.

If the caller didn't specify a node, look under "of_chosen".

With a future patch, this will support "linux,pci-probe-only" on a per host
bridge basis based on the presence of the property in the respective PCI
host bridge DT node.

Implement of_pci_check_probe_only() using of_pci_preserve_config().

Link: https://lore.kernel.org/r/20240508174138.3630283-3-vidyas@nvidia.com
Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Vidya Sagar 2024-05-08 23:11:36 +05:30 committed by Bjorn Helgaas
parent 9d7d5db8e7
commit 407abde9ca
2 changed files with 53 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

60
drivers/pci/of.c
View File

@ -233,28 +233,62 @@ int of_get_pci_domain_nr(struct device_node *node)
}
EXPORT_SYMBOL_GPL(of_get_pci_domain_nr);
/**
* of_pci_preserve_config - Return true if the boot configuration needs to
* be preserved
* @node: Device tree node.
*
* Look for "linux,pci-probe-only" property for a given PCI controller's
* node and return true if found. Also look in the chosen node if the
* property is not found in the given controller's node. Having this
* property ensures that the kernel doesn't reconfigure the BARs and bridge
* windows that are already done by the platform firmware.
*
* Return: true if the property exists; false otherwise.
*/
bool of_pci_preserve_config(struct device_node *node)
{
u32 val = 0;
int ret;
if (!node) {
pr_warn("device node is NULL, trying with of_chosen\n");
node = of_chosen;
}
retry:
ret = of_property_read_u32(node, "linux,pci-probe-only", &val);
if (ret) {
if (ret == -ENODATA || ret == -EOVERFLOW) {
pr_warn("Incorrect value for linux,pci-probe-only in %pOF, ignoring\n",
node);
return false;
}
if (ret == -EINVAL) {
if (node == of_chosen)
return false;
node = of_chosen;
goto retry;
}
}
if (val)
return true;
else
return false;
}
/**
* of_pci_check_probe_only - Setup probe only mode if linux,pci-probe-only
* is present and valid
*/
void of_pci_check_probe_only(void)
{
u32 val;
int ret;
ret = of_property_read_u32(of_chosen, "linux,pci-probe-only", &val);
if (ret) {
if (ret == -ENODATA || ret == -EOVERFLOW)
pr_warn("linux,pci-probe-only without valid value, ignoring\n");
return;
}
if (val)
if (of_pci_preserve_config(of_chosen))
pci_add_flags(PCI_PROBE_ONLY);
else
pci_clear_flags(PCI_PROBE_ONLY);
pr_info("PROBE_ONLY %s\n", val ? "enabled" : "disabled");
}
EXPORT_SYMBOL_GPL(of_pci_check_probe_only);

6
drivers/pci/pci.h
View File

@ -648,6 +648,7 @@ int of_pci_get_max_link_speed(struct device_node *node);
u32 of_pci_get_slot_power_limit(struct device_node *node,
u8 *slot_power_limit_value,
u8 *slot_power_limit_scale);
bool of_pci_preserve_config(struct device_node *node);
int pci_set_of_node(struct pci_dev *dev);
void pci_release_of_node(struct pci_dev *dev);
void pci_set_bus_of_node(struct pci_bus *bus);
@ -686,6 +687,11 @@ of_pci_get_slot_power_limit(struct device_node *node,
return 0;
}
static inline bool of_pci_preserve_config(struct device_node *node)
{
return false;
}
static inline int pci_set_of_node(struct pci_dev *dev) { return 0; }
static inline void pci_release_of_node(struct pci_dev *dev) { }
static inline void pci_set_bus_of_node(struct pci_bus *bus) { }