// SPDX-License-Identifier: GPL-2.0 /* * PCI Virtual Channel support * * Copyright (C) 2013 Red Hat, Inc. All rights reserved. * Author: Alex Williamson <alex.williamson@redhat.com> */ #include <linux/device.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/pci.h> #include <linux/pci_regs.h> #include <linux/types.h> #include "pci.h" /** * pci_vc_save_restore_dwords - Save or restore a series of dwords * @dev: device * @pos: starting config space position * @buf: buffer to save to or restore from * @dwords: number of dwords to save/restore * @save: whether to save or restore */ static void pci_vc_save_restore_dwords(struct pci_dev *dev, int pos, u32 *buf, int dwords, bool save) { int i; for (i = 0; i < dwords; i++, buf++) { if (save) pci_read_config_dword(dev, pos + (i * 4), buf); else pci_write_config_dword(dev, pos + (i * 4), *buf); } } /** * pci_vc_load_arb_table - load and wait for VC arbitration table * @dev: device * @pos: starting position of VC capability (VC/VC9/MFVC) * * Set Load VC Arbitration Table bit requesting hardware to apply the VC * Arbitration Table (previously loaded). When the VC Arbitration Table * Status clears, hardware has latched the table into VC arbitration logic. */ static void pci_vc_load_arb_table(struct pci_dev *dev, int pos) { u16 ctrl; pci_read_config_word(dev, pos + PCI_VC_PORT_CTRL, &ctrl); pci_write_config_word(dev, pos + PCI_VC_PORT_CTRL, ctrl | PCI_VC_PORT_CTRL_LOAD_TABLE); if (pci_wait_for_pending(dev, pos + PCI_VC_PORT_STATUS, PCI_VC_PORT_STATUS_TABLE)) return; pci_err(dev, "VC arbitration table failed to load\n"); } /** * pci_vc_load_port_arb_table - Load and wait for VC port arbitration table * @dev: device * @pos: starting position of VC capability (VC/VC9/MFVC) * @res: VC resource number, ie. VCn (0-7) * * Set Load Port Arbitration Table bit requesting hardware to apply the Port * Arbitration Table (previously loaded). When the Port Arbitration Table * Status clears, hardware has latched the table into port arbitration logic. */ static void pci_vc_load_port_arb_table(struct pci_dev *dev, int pos, int res) { int ctrl_pos, status_pos; u32 ctrl; ctrl_pos = pos + PCI_VC_RES_CTRL + (res * PCI_CAP_VC_PER_VC_SIZEOF); status_pos = pos + PCI_VC_RES_STATUS + (res * PCI_CAP_VC_PER_VC_SIZEOF); pci_read_config_dword(dev, ctrl_pos, &ctrl); pci_write_config_dword(dev, ctrl_pos, ctrl | PCI_VC_RES_CTRL_LOAD_TABLE); if (pci_wait_for_pending(dev, status_pos, PCI_VC_RES_STATUS_TABLE)) return; pci_err(dev, "VC%d port arbitration table failed to load\n", res); } /** * pci_vc_enable - Enable virtual channel * @dev: device * @pos: starting position of VC capability (VC/VC9/MFVC) * @res: VC res number, ie. VCn (0-7) * * A VC is enabled by setting the enable bit in matching resource control * registers on both sides of a link. We therefore need to find the opposite * end of the link. To keep this simple we enable from the downstream device. * RC devices do not have an upstream device, nor does it seem that VC9 do * (spec is unclear). Once we find the upstream device, match the VC ID to * get the correct resource, disable and enable on both ends. */ static void pci_vc_enable(struct pci_dev *dev, int pos, int res) { int ctrl_pos, status_pos, id, pos2, evcc, i, ctrl_pos2, status_pos2; u32 ctrl, header, cap1, ctrl2; struct pci_dev *link = NULL; /* Enable VCs from the downstream device */ if (!pci_is_pcie(dev) || !pcie_downstream_port(dev)) return; ctrl_pos = pos + PCI_VC_RES_CTRL + (res * PCI_CAP_VC_PER_VC_SIZEOF); status_pos = pos + PCI_VC_RES_STATUS + (res * PCI_CAP_VC_PER_VC_SIZEOF); pci_read_config_dword(dev, ctrl_pos, &ctrl); id = ctrl & PCI_VC_RES_CTRL_ID; pci_read_config_dword(dev, pos, &header); /* If there is no opposite end of the link, skip to enable */ if (PCI_EXT_CAP_ID(header) == PCI_EXT_CAP_ID_VC9 || pci_is_root_bus(dev->bus)) goto enable; pos2 = pci_find_ext_capability(dev->bus->self, PCI_EXT_CAP_ID_VC); if (!pos2) goto enable; pci_read_config_dword(dev->bus->self, pos2 + PCI_VC_PORT_CAP1, &cap1); evcc = cap1 & PCI_VC_CAP1_EVCC; /* VC0 is hardwired enabled, so we can start with 1 */ for (i = 1; i < evcc + 1; i++) { ctrl_pos2 = pos2 + PCI_VC_RES_CTRL + (i * PCI_CAP_VC_PER_VC_SIZEOF); status_pos2 = pos2 + PCI_VC_RES_STATUS + (i * PCI_CAP_VC_PER_VC_SIZEOF); pci_read_config_dword(dev->bus->self, ctrl_pos2, &ctrl2); if ((ctrl2 & PCI_VC_RES_CTRL_ID) == id) { link = dev->bus->self; break; } } if (!link) goto enable; /* Disable if enabled */ if (ctrl2 & PCI_VC_RES_CTRL_ENABLE) { ctrl2 &= ~PCI_VC_RES_CTRL_ENABLE; pci_write_config_dword(link, ctrl_pos2, ctrl2); } /* Enable on both ends */ ctrl2 |= PCI_VC_RES_CTRL_ENABLE; pci_write_config_dword(link, ctrl_pos2, ctrl2); enable: ctrl |= PCI_VC_RES_CTRL_ENABLE; pci_write_config_dword(dev, ctrl_pos, ctrl); if (!pci_wait_for_pending(dev, status_pos, PCI_VC_RES_STATUS_NEGO)) pci_err(dev, "VC%d negotiation stuck pending\n", id); if (link && !pci_wait_for_pending(link, status_pos2, PCI_VC_RES_STATUS_NEGO)) pci_err(link, "VC%d negotiation stuck pending\n", id); } /** * pci_vc_do_save_buffer - Size, save, or restore VC state * @dev: device * @pos: starting position of VC capability (VC/VC9/MFVC) * @save_state: buffer for save/restore * @save: if provided a buffer, this indicates what to do with it * * Walking Virtual Channel config space to size, save, or restore it * is complicated, so we do it all from one function to reduce code and * guarantee ordering matches in the buffer. When called with NULL * @save_state, return the size of the necessary save buffer. When called * with a non-NULL @save_state, @save determines whether we save to the * buffer or restore from it. */ static int pci_vc_do_save_buffer(struct pci_dev *dev, int pos, struct pci_cap_saved_state *save_state, bool save) { u32 cap1; char evcc, lpevcc, parb_size; int i, len = 0; u8 *buf = save_state ? (u8 *)save_state->cap.data : NULL; /* Sanity check buffer size for save/restore */ if (buf && save_state->cap.size != pci_vc_do_save_buffer(dev, pos, NULL, save)) { pci_err(dev, "VC save buffer size does not match @0x%x\n", pos); return -ENOMEM; } pci_read_config_dword(dev, pos + PCI_VC_PORT_CAP1, &cap1); /* Extended VC Count (not counting VC0) */ evcc = cap1 & PCI_VC_CAP1_EVCC; /* Low Priority Extended VC Count (not counting VC0) */ lpevcc = (cap1 & PCI_VC_CAP1_LPEVCC) >> 4; /* Port Arbitration Table Entry Size (bits) */ parb_size = 1 << ((cap1 & PCI_VC_CAP1_ARB_SIZE) >> 10); /* * Port VC Control Register contains VC Arbitration Select, which * cannot be modified when more than one LPVC is in operation. We * therefore save/restore it first, as only VC0 should be enabled * after device reset. */ if (buf) { if (save) pci_read_config_word(dev, pos + PCI_VC_PORT_CTRL, (u16 *)buf); else pci_write_config_word(dev, pos + PCI_VC_PORT_CTRL, *(u16 *)buf); buf += 4; } len += 4; /* * If we have any Low Priority VCs and a VC Arbitration Table Offset * in Port VC Capability Register 2 then save/restore it next. */ if (lpevcc) { u32 cap2; int vcarb_offset; pci_read_config_dword(dev, pos + PCI_VC_PORT_CAP2, &cap2); vcarb_offset = ((cap2 & PCI_VC_CAP2_ARB_OFF) >> 24) * 16; if (vcarb_offset) { int size, vcarb_phases = 0; if (cap2 & PCI_VC_CAP2_128_PHASE) vcarb_phases = 128; else if (cap2 & PCI_VC_CAP2_64_PHASE) vcarb_phases = 64; else if (cap2 & PCI_VC_CAP2_32_PHASE) vcarb_phases = 32; /* Fixed 4 bits per phase per lpevcc (plus VC0) */ size = ((lpevcc + 1) * vcarb_phases * 4) / 8; if (size && buf) { pci_vc_save_restore_dwords(dev, pos + vcarb_offset, (u32 *)buf, size / 4, save); /* * On restore, we need to signal hardware to * re-load the VC Arbitration Table. */ if (!save) pci_vc_load_arb_table(dev, pos); buf += size; } len += size; } } /* * In addition to each VC Resource Control Register, we may have a * Port Arbitration Table attached to each VC. The Port Arbitration * Table Offset in each VC Resource Capability Register tells us if * it exists. The entry size is global from the Port VC Capability * Register1 above. The number of phases is determined per VC. */ for (i = 0; i < evcc + 1; i++) { u32 cap; int parb_offset; pci_read_config_dword(dev, pos + PCI_VC_RES_CAP + (i * PCI_CAP_VC_PER_VC_SIZEOF), &cap); parb_offset = ((cap & PCI_VC_RES_CAP_ARB_OFF) >> 24) * 16; if (parb_offset) { int size, parb_phases = 0; if (cap & PCI_VC_RES_CAP_256_PHASE) parb_phases = 256; else if (cap & (PCI_VC_RES_CAP_128_PHASE | PCI_VC_RES_CAP_128_PHASE_TB)) parb_phases = 128; else if (cap & PCI_VC_RES_CAP_64_PHASE) parb_phases = 64; else if (cap & PCI_VC_RES_CAP_32_PHASE) parb_phases = 32; size = (parb_size * parb_phases) / 8; if (size && buf) { pci_vc_save_restore_dwords(dev, pos + parb_offset, (u32 *)buf, size / 4, save); buf += size; } len += size; } /* VC Resource Control Register */ if (buf) { int ctrl_pos = pos + PCI_VC_RES_CTRL + (i * PCI_CAP_VC_PER_VC_SIZEOF); if (save) pci_read_config_dword(dev, ctrl_pos, (u32 *)buf); else { u32 tmp, ctrl = *(u32 *)buf; /* * For an FLR case, the VC config may remain. * Preserve enable bit, restore the rest. */ pci_read_config_dword(dev, ctrl_pos, &tmp); tmp &= PCI_VC_RES_CTRL_ENABLE; tmp |= ctrl & ~PCI_VC_RES_CTRL_ENABLE; pci_write_config_dword(dev, ctrl_pos, tmp); /* Load port arbitration table if used */ if (ctrl & PCI_VC_RES_CTRL_ARB_SELECT) pci_vc_load_port_arb_table(dev, pos, i); /* Re-enable if needed */ if ((ctrl ^ tmp) & PCI_VC_RES_CTRL_ENABLE) pci_vc_enable(dev, pos, i); } buf += 4; } len += 4; } return buf ? 0 : len; } static struct { u16 id; const char *name; } vc_caps[] = { { PCI_EXT_CAP_ID_MFVC, "MFVC" }, { PCI_EXT_CAP_ID_VC, "VC" }, { PCI_EXT_CAP_ID_VC9, "VC9" } }; /** * pci_save_vc_state - Save VC state to pre-allocate save buffer * @dev: device * * For each type of VC capability, VC/VC9/MFVC, find the capability and * save it to the pre-allocated save buffer. */ int pci_save_vc_state(struct pci_dev *dev) { int i; for (i = 0; i < ARRAY_SIZE(vc_caps); i++) { int pos, ret; struct pci_cap_saved_state *save_state; pos = pci_find_ext_capability(dev, vc_caps[i].id); if (!pos) continue; save_state = pci_find_saved_ext_cap(dev, vc_caps[i].id); if (!save_state) { pci_err(dev, "%s buffer not found in %s\n", vc_caps[i].name, __func__); return -ENOMEM; } ret = pci_vc_do_save_buffer(dev, pos, save_state, true); if (ret) { pci_err(dev, "%s save unsuccessful %s\n", vc_caps[i].name, __func__); return ret; } } return 0; } /** * pci_restore_vc_state - Restore VC state from save buffer * @dev: device * * For each type of VC capability, VC/VC9/MFVC, find the capability and * restore it from the previously saved buffer. */ void pci_restore_vc_state(struct pci_dev *dev) { int i; for (i = 0; i < ARRAY_SIZE(vc_caps); i++) { int pos; struct pci_cap_saved_state *save_state; pos = pci_find_ext_capability(dev, vc_caps[i].id); save_state = pci_find_saved_ext_cap(dev, vc_caps[i].id); if (!save_state || !pos) continue; pci_vc_do_save_buffer(dev, pos, save_state, false); } } /** * pci_allocate_vc_save_buffers - Allocate save buffers for VC caps * @dev: device * * For each type of VC capability, VC/VC9/MFVC, find the capability, size * it, and allocate a buffer for save/restore. */ void pci_allocate_vc_save_buffers(struct pci_dev *dev) { int i; for (i = 0; i < ARRAY_SIZE(vc_caps); i++) { int len, pos = pci_find_ext_capability(dev, vc_caps[i].id); if (!pos) continue; len = pci_vc_do_save_buffer(dev, pos, NULL, false); if (pci_add_ext_cap_save_buffer(dev, vc_caps[i].id, len)) pci_err(dev, "unable to preallocate %s save buffer\n", vc_caps[i].name); } }