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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 | // SPDX-License-Identifier: GPL-2.0+ /* * (C) Copyright 2022 Microsoft Corporation <www.microsoft.com> * Stephen Carlson <stcarlso@linux.microsoft.com> * * PCI Express Maximum Packet Size (MPS) configuration */ #include <bootretry.h> #include <cli.h> #include <command.h> #include <console.h> #include <dm.h> #include <init.h> #include <asm/processor.h> #include <asm/io.h> #include <pci.h> #define PCI_MPS_SAFE 0 #define PCI_MPS_PEER2PEER 1 static int pci_mps_find_safe(struct udevice *bus, unsigned int *min_mps, unsigned int *n) { struct udevice *dev; int res = 0, addr; unsigned int mpss; u32 regval; if (!min_mps || !n) return -EINVAL; for (device_find_first_child(bus, &dev); dev; device_find_next_child(&dev)) { addr = dm_pci_find_capability(dev, PCI_CAP_ID_EXP); if (addr <= 0) continue; res = dm_pci_read_config32(dev, addr + PCI_EXP_DEVCAP, ®val); if (res != 0) return res; mpss = (unsigned int)(regval & PCI_EXP_DEVCAP_PAYLOAD); *n += 1; if (mpss < *min_mps) *min_mps = mpss; } return res; } static int pci_mps_set_bus(struct udevice *bus, unsigned int target) { struct udevice *dev; u32 mpss, target_mps = (u32)(target << 5); u16 mps; int res = 0, addr; for (device_find_first_child(bus, &dev); dev && res == 0; device_find_next_child(&dev)) { addr = dm_pci_find_capability(dev, PCI_CAP_ID_EXP); if (addr <= 0) continue; res = dm_pci_read_config32(dev, addr + PCI_EXP_DEVCAP, &mpss); if (res != 0) return res; /* Do not set device above its maximum MPSS */ mpss = (mpss & PCI_EXP_DEVCAP_PAYLOAD) << 5; if (target_mps < mpss) mps = (u16)target_mps; else mps = (u16)mpss; res = dm_pci_clrset_config16(dev, addr + PCI_EXP_DEVCTL, PCI_EXP_DEVCTL_PAYLOAD, mps); } return res; } /* * Sets the MPS of each PCI Express device to the specified policy. */ static int pci_mps_set(int policy) { struct udevice *bus; int i, res = 0; /* 0 = 128B, min value for hotplug */ unsigned int mps = 0; if (policy == PCI_MPS_SAFE) { unsigned int min_mps = PCI_EXP_DEVCAP_PAYLOAD_4096B, n = 0; /* Find maximum MPS supported by all devices */ for (i = 0; uclass_get_device_by_seq(UCLASS_PCI, i, &bus) == 0 && res == 0; i++) res = pci_mps_find_safe(bus, &min_mps, &n); /* If no devices were found, do not reconfigure */ if (n == 0) return res; mps = min_mps; } /* This message is checked by the sandbox test */ printf("Setting MPS of all devices to %uB\n", 128U << mps); for (i = 0; uclass_get_device_by_seq(UCLASS_PCI, i, &bus) == 0 && res == 0; i++) res = pci_mps_set_bus(bus, mps); return res; } /* * PCI MPS tuning commands * * Syntax: * pci_mps safe * pci_mps peer2peer */ static int do_pci_mps(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[]) { char cmd = 'u'; int ret = 0; if (argc > 1) cmd = argv[1][0]; switch (cmd) { case 's': /* safe */ ret = pci_mps_set(PCI_MPS_SAFE); break; case 'p': /* peer2peer/hotplug */ ret = pci_mps_set(PCI_MPS_PEER2PEER); break; default: /* usage, help */ goto usage; } return ret; usage: return CMD_RET_USAGE; } /***************************************************/ U_BOOT_LONGHELP(pci_mps, "safe\n" " - Set PCI Express MPS of all devices to safe values\n" "pci_mps peer2peer\n" " - Set PCI Express MPS of all devices to support hotplug and peer-to-peer DMA\n"); U_BOOT_CMD(pci_mps, 2, 0, do_pci_mps, "configure PCI Express MPS", pci_mps_help_text); |