1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Root Complex Event Collector Support
  4 *
  5 * Authors:
  6 *  Sean V Kelley <sean.v.kelley@intel.com>
  7 *  Qiuxu Zhuo <qiuxu.zhuo@intel.com>
  8 *
  9 * Copyright (C) 2020 Intel Corp.
 10 */
 11
 12#include <linux/kernel.h>
 13#include <linux/pci.h>
 14#include <linux/pci_regs.h>
 15
 16#include "../pci.h"
 17
 18struct walk_rcec_data {
 19	struct pci_dev *rcec;
 20	int (*user_callback)(struct pci_dev *dev, void *data);
 21	void *user_data;
 22};
 23
 24static bool rcec_assoc_rciep(struct pci_dev *rcec, struct pci_dev *rciep)
 25{
 26	unsigned long bitmap = rcec->rcec_ea->bitmap;
 27	unsigned int devn;
 28
 29	/* An RCiEP found on a different bus in range */
 30	if (rcec->bus->number != rciep->bus->number)
 31		return true;
 32
 33	/* Same bus, so check bitmap */
 34	for_each_set_bit(devn, &bitmap, 32)
 35		if (devn == PCI_SLOT(rciep->devfn))
 36			return true;
 37
 38	return false;
 39}
 40
 41static int link_rcec_helper(struct pci_dev *dev, void *data)
 42{
 43	struct walk_rcec_data *rcec_data = data;
 44	struct pci_dev *rcec = rcec_data->rcec;
 45
 46	if ((pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) &&
 47	    rcec_assoc_rciep(rcec, dev)) {
 48		dev->rcec = rcec;
 49		pci_dbg(dev, "PME & error events signaled via %s\n",
 50			pci_name(rcec));
 51	}
 52
 53	return 0;
 54}
 55
 56static int walk_rcec_helper(struct pci_dev *dev, void *data)
 57{
 58	struct walk_rcec_data *rcec_data = data;
 59	struct pci_dev *rcec = rcec_data->rcec;
 60
 61	if ((pci_pcie_type(dev) == PCI_EXP_TYPE_RC_END) &&
 62	    rcec_assoc_rciep(rcec, dev))
 63		rcec_data->user_callback(dev, rcec_data->user_data);
 64
 65	return 0;
 66}
 67
 68static void walk_rcec(int (*cb)(struct pci_dev *dev, void *data),
 69		      void *userdata)
 70{
 71	struct walk_rcec_data *rcec_data = userdata;
 72	struct pci_dev *rcec = rcec_data->rcec;
 73	u8 nextbusn, lastbusn;
 74	struct pci_bus *bus;
 75	unsigned int bnr;
 76
 77	if (!rcec->rcec_ea)
 78		return;
 79
 80	/* Walk own bus for bitmap based association */
 81	pci_walk_bus(rcec->bus, cb, rcec_data);
 82
 83	nextbusn = rcec->rcec_ea->nextbusn;
 84	lastbusn = rcec->rcec_ea->lastbusn;
 85
 86	/* All RCiEP devices are on the same bus as the RCEC */
 87	if (nextbusn == 0xff && lastbusn == 0x00)
 88		return;
 89
 90	for (bnr = nextbusn; bnr <= lastbusn; bnr++) {
 91		/* No association indicated (PCIe 5.0-1, 7.9.10.3) */
 92		if (bnr == rcec->bus->number)
 93			continue;
 94
 95		bus = pci_find_bus(pci_domain_nr(rcec->bus), bnr);
 96		if (!bus)
 97			continue;
 98
 99		/* Find RCiEP devices on the given bus ranges */
100		pci_walk_bus(bus, cb, rcec_data);
101	}
102}
103
104/**
105 * pcie_link_rcec - Link RCiEP devices associated with RCEC.
106 * @rcec: RCEC whose RCiEP devices should be linked.
107 *
108 * Link the given RCEC to each RCiEP device found.
109 */
110void pcie_link_rcec(struct pci_dev *rcec)
111{
112	struct walk_rcec_data rcec_data;
113
114	if (!rcec->rcec_ea)
115		return;
116
117	rcec_data.rcec = rcec;
118	rcec_data.user_callback = NULL;
119	rcec_data.user_data = NULL;
120
121	walk_rcec(link_rcec_helper, &rcec_data);
122}
123
124/**
125 * pcie_walk_rcec - Walk RCiEP devices associating with RCEC and call callback.
126 * @rcec:	RCEC whose RCiEP devices should be walked
127 * @cb:		Callback to be called for each RCiEP device found
128 * @userdata:	Arbitrary pointer to be passed to callback
129 *
130 * Walk the given RCEC. Call the callback on each RCiEP found.
131 *
132 * If @cb returns anything other than 0, break out.
133 */
134void pcie_walk_rcec(struct pci_dev *rcec, int (*cb)(struct pci_dev *, void *),
135		    void *userdata)
136{
137	struct walk_rcec_data rcec_data;
138
139	if (!rcec->rcec_ea)
140		return;
141
142	rcec_data.rcec = rcec;
143	rcec_data.user_callback = cb;
144	rcec_data.user_data = userdata;
145
146	walk_rcec(walk_rcec_helper, &rcec_data);
147}
148
149void pci_rcec_init(struct pci_dev *dev)
150{
151	struct rcec_ea *rcec_ea;
152	u32 rcec, hdr, busn;
153	u8 ver;
154
155	/* Only for Root Complex Event Collectors */
156	if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_EC)
157		return;
158
159	rcec = pci_find_ext_capability(dev, PCI_EXT_CAP_ID_RCEC);
160	if (!rcec)
161		return;
162
163	rcec_ea = kzalloc(sizeof(*rcec_ea), GFP_KERNEL);
164	if (!rcec_ea)
165		return;
166
167	pci_read_config_dword(dev, rcec + PCI_RCEC_RCIEP_BITMAP,
168			      &rcec_ea->bitmap);
169
170	/* Check whether RCEC BUSN register is present */
171	pci_read_config_dword(dev, rcec, &hdr);
172	ver = PCI_EXT_CAP_VER(hdr);
173	if (ver >= PCI_RCEC_BUSN_REG_VER) {
174		pci_read_config_dword(dev, rcec + PCI_RCEC_BUSN, &busn);
175		rcec_ea->nextbusn = PCI_RCEC_BUSN_NEXT(busn);
176		rcec_ea->lastbusn = PCI_RCEC_BUSN_LAST(busn);
177	} else {
178		/* Avoid later ver check by setting nextbusn */
179		rcec_ea->nextbusn = 0xff;
180		rcec_ea->lastbusn = 0x00;
181	}
182
183	dev->rcec_ea = rcec_ea;
184}
185
186void pci_rcec_exit(struct pci_dev *dev)
187{
188	kfree(dev->rcec_ea);
189	dev->rcec_ea = NULL;
190}