1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * PCI Error Disconnect Recover support
  4 * Author: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
  5 *
  6 * Copyright (C) 2020 Intel Corp.
  7 */
  8
  9#define dev_fmt(fmt) "EDR: " fmt
 10
 11#include <linux/pci.h>
 12#include <linux/pci-acpi.h>
 13
 14#include "portdrv.h"
 15#include "../pci.h"
 16
 17#define EDR_PORT_DPC_ENABLE_DSM		0x0C
 18#define EDR_PORT_LOCATE_DSM		0x0D
 19#define EDR_OST_SUCCESS			0x80
 20#define EDR_OST_FAILED			0x81
 21
 22/*
 23 * _DSM wrapper function to enable/disable DPC
 24 * @pdev   : PCI device structure
 25 *
 26 * returns 0 on success or errno on failure.
 27 */
 28static int acpi_enable_dpc(struct pci_dev *pdev)
 29{
 30	struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
 31	union acpi_object *obj, argv4, req;
 32	int status = 0;
 33
 34	/*
 35	 * Behavior when calling unsupported _DSM functions is undefined,
 36	 * so check whether EDR_PORT_DPC_ENABLE_DSM is supported.
 37	 */
 38	if (!acpi_check_dsm(adev->handle, &pci_acpi_dsm_guid, 5,
 39			    1ULL << EDR_PORT_DPC_ENABLE_DSM))
 40		return 0;
 41
 42	req.type = ACPI_TYPE_INTEGER;
 43	req.integer.value = 1;
 44
 45	argv4.type = ACPI_TYPE_PACKAGE;
 46	argv4.package.count = 1;
 47	argv4.package.elements = &req;
 48
 49	/*
 50	 * Per Downstream Port Containment Related Enhancements ECN to PCI
 51	 * Firmware Specification r3.2, sec 4.6.12, EDR_PORT_DPC_ENABLE_DSM is
 52	 * optional.  Return success if it's not implemented.
 53	 */
 54	obj = acpi_evaluate_dsm(adev->handle, &pci_acpi_dsm_guid, 5,
 55				EDR_PORT_DPC_ENABLE_DSM, &argv4);
 56	if (!obj)
 57		return 0;
 58
 59	if (obj->type != ACPI_TYPE_INTEGER) {
 60		pci_err(pdev, FW_BUG "Enable DPC _DSM returned non integer\n");
 61		status = -EIO;
 62	}
 63
 64	if (obj->integer.value != 1) {
 65		pci_err(pdev, "Enable DPC _DSM failed to enable DPC\n");
 66		status = -EIO;
 67	}
 68
 69	ACPI_FREE(obj);
 70
 71	return status;
 72}
 73
 74/*
 75 * _DSM wrapper function to locate DPC port
 76 * @pdev   : Device which received EDR event
 77 *
 78 * Returns pci_dev or NULL.  Caller is responsible for dropping a reference
 79 * on the returned pci_dev with pci_dev_put().
 80 */
 81static struct pci_dev *acpi_dpc_port_get(struct pci_dev *pdev)
 82{
 83	struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
 84	union acpi_object *obj;
 85	u16 port;
 86
 87	/*
 88	 * Behavior when calling unsupported _DSM functions is undefined,
 89	 * so check whether EDR_PORT_DPC_ENABLE_DSM is supported.
 90	 */
 91	if (!acpi_check_dsm(adev->handle, &pci_acpi_dsm_guid, 5,
 92			    1ULL << EDR_PORT_LOCATE_DSM))
 93		return pci_dev_get(pdev);
 94
 95	obj = acpi_evaluate_dsm(adev->handle, &pci_acpi_dsm_guid, 5,
 96				EDR_PORT_LOCATE_DSM, NULL);
 97	if (!obj)
 98		return pci_dev_get(pdev);
 99
100	if (obj->type != ACPI_TYPE_INTEGER) {
101		ACPI_FREE(obj);
102		pci_err(pdev, FW_BUG "Locate Port _DSM returned non integer\n");
103		return NULL;
104	}
105
106	/*
107	 * Firmware returns DPC port BDF details in following format:
108	 *	15:8 = bus
109	 *	 7:3 = device
110	 *	 2:0 = function
111	 */
112	port = obj->integer.value;
113
114	ACPI_FREE(obj);
115
116	return pci_get_domain_bus_and_slot(pci_domain_nr(pdev->bus),
117					   PCI_BUS_NUM(port), port & 0xff);
118}
119
120/*
121 * _OST wrapper function to let firmware know the status of EDR event
122 * @pdev   : Device used to send _OST
123 * @edev   : Device which experienced EDR event
124 * @status : Status of EDR event
125 */
126static int acpi_send_edr_status(struct pci_dev *pdev, struct pci_dev *edev,
127				u16 status)
128{
129	struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
130	u32 ost_status;
131
132	pci_dbg(pdev, "Status for %s: %#x\n", pci_name(edev), status);
133
134	ost_status = PCI_DEVID(edev->bus->number, edev->devfn) << 16;
135	ost_status |= status;
136
137	status = acpi_evaluate_ost(adev->handle, ACPI_NOTIFY_DISCONNECT_RECOVER,
138				   ost_status, NULL);
139	if (ACPI_FAILURE(status))
140		return -EINVAL;
141
142	return 0;
143}
144
145static void edr_handle_event(acpi_handle handle, u32 event, void *data)
146{
147	struct pci_dev *pdev = data, *edev;
148	pci_ers_result_t estate = PCI_ERS_RESULT_DISCONNECT;
149	u16 status;
150
151	if (event != ACPI_NOTIFY_DISCONNECT_RECOVER)
152		return;
153
154	/*
155	 * pdev is a Root Port or Downstream Port that is still present and
156	 * has triggered a containment event, e.g., DPC, so its child
157	 * devices have been disconnected (ACPI r6.5, sec 5.6.6).
158	 */
159	pci_info(pdev, "EDR event received\n");
160
161	/*
162	 * Locate the port that experienced the containment event.  pdev
163	 * may be that port or a parent of it (PCI Firmware r3.3, sec
164	 * 4.6.13).
165	 */
166	edev = acpi_dpc_port_get(pdev);
167	if (!edev) {
168		pci_err(pdev, "Firmware failed to locate DPC port\n");
169		return;
170	}
171
172	pci_dbg(pdev, "Reported EDR dev: %s\n", pci_name(edev));
173
174	/* If port does not support DPC, just send the OST */
175	if (!edev->dpc_cap) {
176		pci_err(edev, FW_BUG "This device doesn't support DPC\n");
177		goto send_ost;
178	}
179
180	/* Check if there is a valid DPC trigger */
181	pci_read_config_word(edev, edev->dpc_cap + PCI_EXP_DPC_STATUS, &status);
182	if (!(status & PCI_EXP_DPC_STATUS_TRIGGER)) {
183		pci_err(edev, "Invalid DPC trigger %#010x\n", status);
184		goto send_ost;
185	}
186
187	dpc_process_error(edev);
188	pci_aer_raw_clear_status(edev);
189
190	/*
191	 * Irrespective of whether the DPC event is triggered by ERR_FATAL
192	 * or ERR_NONFATAL, since the link is already down, use the FATAL
193	 * error recovery path for both cases.
194	 */
195	estate = pcie_do_recovery(edev, pci_channel_io_frozen, dpc_reset_link);
196
197send_ost:
198
199	/*
200	 * If recovery is successful, send _OST(0xF, BDF << 16 | 0x80)
201	 * to firmware. If not successful, send _OST(0xF, BDF << 16 | 0x81).
202	 */
203	if (estate == PCI_ERS_RESULT_RECOVERED) {
204		pci_dbg(edev, "DPC port successfully recovered\n");
205		pcie_clear_device_status(edev);
206		acpi_send_edr_status(pdev, edev, EDR_OST_SUCCESS);
207	} else {
208		pci_dbg(edev, "DPC port recovery failed\n");
209		acpi_send_edr_status(pdev, edev, EDR_OST_FAILED);
210	}
211
212	pci_dev_put(edev);
213}
214
215void pci_acpi_add_edr_notifier(struct pci_dev *pdev)
216{
217	struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
218	acpi_status status;
219
220	if (!adev) {
221		pci_dbg(pdev, "No valid ACPI node, skipping EDR init\n");
222		return;
223	}
224
225	status = acpi_install_notify_handler(adev->handle, ACPI_SYSTEM_NOTIFY,
226					     edr_handle_event, pdev);
227	if (ACPI_FAILURE(status)) {
228		pci_err(pdev, "Failed to install notify handler\n");
229		return;
230	}
231
232	if (acpi_enable_dpc(pdev))
233		acpi_remove_notify_handler(adev->handle, ACPI_SYSTEM_NOTIFY,
234					   edr_handle_event);
235	else
236		pci_dbg(pdev, "Notify handler installed\n");
237}
238
239void pci_acpi_remove_edr_notifier(struct pci_dev *pdev)
240{
241	struct acpi_device *adev = ACPI_COMPANION(&pdev->dev);
242
243	if (!adev)
244		return;
245
246	acpi_remove_notify_handler(adev->handle, ACPI_SYSTEM_NOTIFY,
247				   edr_handle_event);
248	pci_dbg(pdev, "Notify handler removed\n");
249}