soc/intel/common/pcie: Allow pcie_rp_group table to be non-contiguous

In case of CPU PCIe RPs, the RP numbers might not be contiguous for
all the functions in a slot.

Example: In ADL, RP1 is 00:06.0, RP2 is 00:01.0 and RP3 is 00:06.2 as
per the FSP expectations.

Hence, this change updates the defintion of `struct pcie_rp_group` to
include a `start` member which indicates the starting PCI function
number within the group. All common functions for PCIe RP are
accordingly updated to take the `start` member into account.

Thus, in the above example, ADL can provide a cpu_rp_table as follows:
{
  { .slot = PCIE_SLOT_6, .start = 0, .count = 1 },
  { .slot = PCIE_SLOT_1, .start = 0, .count = 1 },
  { .slot = PCIE_SLOT_6, .start = 2, .count = 1 },
}

Since start defaults to 0 when uninitialized, current PCH RP group
tables don't need to be updated.

Change-Id: Idf80a0f29e7c315105f76a7460c8e1e8f9a10d25
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/49370
Reviewed-by: Nico Huber <nico.h@gmx.de>
Reviewed-by: EricR Lai <ericr_lai@compal.corp-partner.google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/soc/intel/common/block/include/intelblocks/pcie_rp.h

@@ -10,15 +10,27 @@
  * functions.
  *
  * `slot` is the PCI device/slot number of such a group.
- * `count` is the number of functions within the group. It is assumed that
- * the first group includes the RPs 1 to the first group's `count` and that
- * adjacent groups follow without gaps in the numbering.
+ * `start` is the initial PCI function number within the group. This is useful in case the
+ * root port numbers are not contiguous within the slot.
+ * `count` is the number of functions within the group starting with the `start` function
+ * number.
  */
 struct pcie_rp_group {
 	unsigned int slot;
+	unsigned int start;
 	unsigned int count;
 };
 
+static inline unsigned int rp_start_fn(const struct pcie_rp_group *group)
+{
+	return group->start;
+}
+
+static inline unsigned int rp_end_fn(const struct pcie_rp_group *group)
+{
+	return group->start + group->count - 1;
+}
+
 /*
  * Update PCI paths of the root ports in the devicetree.
  *
@@ -32,7 +44,9 @@ struct pcie_rp_group {
  * Call this once, after root ports have been reordered, but before PCI
  * enumeration.
  *
- * `groups` points to a list of groups terminated by an entry with `count == 0`.
+ * `groups` points to a list of groups terminated by an entry with `count == 0`. It is assumed
+ * that the first group includes the RPs 1 to the first group's `count` and that adjacent groups
+ * follow without gaps in the numbering.
  */
 void pcie_rp_update_devicetree(const struct pcie_rp_group *groups);
 

src/soc/intel/common/block/pcie/pcie_helpers.c

@@ -5,14 +5,15 @@
 #include <intelblocks/pcie_rp.h>
 #include <stdint.h>
 
-static uint32_t pcie_slot_enable_mask(unsigned int slot, unsigned int count)
+static uint32_t pcie_slot_enable_mask(const struct pcie_rp_group *group)
 {
 	uint32_t mask = 0;
+	unsigned int fn;
 	unsigned int i;
 	const struct device *dev;
 
-	for (i = 0; i < count; i++) {
-		dev = pcidev_on_root(slot, i);
+	for (i = 0, fn = rp_start_fn(group); i < group->count; i++, fn++) {
+		dev = pcidev_on_root(group->slot, fn);
 		if (is_dev_enabled(dev))
 			mask |= BIT(i);
 	}
@@ -32,7 +33,7 @@ uint32_t pcie_rp_enable_mask(const struct pcie_rp_group *const groups)
 			       __func__);
 			break;
 		}
-		mask |= pcie_slot_enable_mask(group->slot, group->count) << offset;
+		mask |= pcie_slot_enable_mask(group) << offset;
 		offset += group->count;
 	}
 

src/soc/intel/common/block/pcie/pcie_rp.c

@@ -54,7 +54,7 @@ static void pcie_rp_scan_groups(int mapping[], const struct pcie_rp_group *const
 	const struct pcie_rp_group *group;
 	for (group = groups; group->count; ++group) {
 		unsigned int fn;
-		for (fn = 0; fn < group->count; ++fn) {
+		for (fn = rp_start_fn(group); fn <= rp_end_fn(group); ++fn) {
 			const pci_devfn_t dev = PCI_DEV(0, group->slot, fn);
 			const uint16_t did = pci_s_read_config16(dev, PCI_DEVICE_ID);
 			if (did == 0xffff) {
@@ -96,7 +96,8 @@ static bool pcie_rp_update_dev(
 	const struct pcie_rp_group *group;
 	for (group = groups; group->count; ++group) {
 		if (PCI_SLOT(dev->path.pci.devfn) == group->slot &&
-		    PCI_FUNC(dev->path.pci.devfn) < group->count)
+		    PCI_FUNC(dev->path.pci.devfn) >= rp_start_fn(group) &&
+		    PCI_FUNC(dev->path.pci.devfn) <= rp_end_fn(group))
 			break;
 		offset += group->count;
 	}