| Stephen Carlson | 3d876c4 | 2023-03-10 11:07:13 -0800 | [diff] [blame] | 1 | // SPDX-License-Identifier: GPL-2.0+ |
| 2 | /* |
| 3 | * (C) Copyright 2022 Microsoft Corporation <www.microsoft.com> |
| 4 | * Stephen Carlson <stcarlso@linux.microsoft.com> |
| 5 | * |
| 6 | * PCI Express Maximum Packet Size (MPS) configuration |
| 7 | */ |
| 8 | |
| 9 | #include <common.h> |
| 10 | #include <bootretry.h> |
| 11 | #include <cli.h> |
| 12 | #include <command.h> |
| 13 | #include <console.h> |
| 14 | #include <dm.h> |
| 15 | #include <init.h> |
| 16 | #include <asm/processor.h> |
| 17 | #include <asm/io.h> |
| 18 | #include <pci.h> |
| 19 | |
| 20 | #define PCI_MPS_SAFE 0 |
| 21 | #define PCI_MPS_PEER2PEER 1 |
| 22 | |
| 23 | static int pci_mps_find_safe(struct udevice *bus, unsigned int *min_mps, |
| 24 | unsigned int *n) |
| 25 | { |
| 26 | struct udevice *dev; |
| 27 | int res = 0, addr; |
| 28 | unsigned int mpss; |
| 29 | u32 regval; |
| 30 | |
| 31 | if (!min_mps || !n) |
| 32 | return -EINVAL; |
| 33 | |
| 34 | for (device_find_first_child(bus, &dev); |
| 35 | dev; |
| 36 | device_find_next_child(&dev)) { |
| 37 | addr = dm_pci_find_capability(dev, PCI_CAP_ID_EXP); |
| 38 | if (addr <= 0) |
| 39 | continue; |
| 40 | |
| 41 | res = dm_pci_read_config32(dev, addr + PCI_EXP_DEVCAP, |
| 42 | ®val); |
| 43 | if (res != 0) |
| 44 | return res; |
| 45 | mpss = (unsigned int)(regval & PCI_EXP_DEVCAP_PAYLOAD); |
| 46 | *n += 1; |
| 47 | if (mpss < *min_mps) |
| 48 | *min_mps = mpss; |
| 49 | } |
| 50 | |
| 51 | return res; |
| 52 | } |
| 53 | |
| 54 | static int pci_mps_set_bus(struct udevice *bus, unsigned int target) |
| 55 | { |
| 56 | struct udevice *dev; |
| 57 | u32 mpss, target_mps = (u32)(target << 5); |
| 58 | u16 mps; |
| 59 | int res = 0, addr; |
| 60 | |
| 61 | for (device_find_first_child(bus, &dev); |
| 62 | dev && res == 0; |
| 63 | device_find_next_child(&dev)) { |
| 64 | addr = dm_pci_find_capability(dev, PCI_CAP_ID_EXP); |
| 65 | if (addr <= 0) |
| 66 | continue; |
| 67 | |
| 68 | res = dm_pci_read_config32(dev, addr + PCI_EXP_DEVCAP, |
| 69 | &mpss); |
| 70 | if (res != 0) |
| 71 | return res; |
| 72 | |
| 73 | /* Do not set device above its maximum MPSS */ |
| 74 | mpss = (mpss & PCI_EXP_DEVCAP_PAYLOAD) << 5; |
| 75 | if (target_mps < mpss) |
| 76 | mps = (u16)target_mps; |
| 77 | else |
| 78 | mps = (u16)mpss; |
| 79 | res = dm_pci_clrset_config16(dev, addr + PCI_EXP_DEVCTL, |
| 80 | PCI_EXP_DEVCTL_PAYLOAD, mps); |
| 81 | } |
| 82 | |
| 83 | return res; |
| 84 | } |
| 85 | |
| 86 | /* |
| 87 | * Sets the MPS of each PCI Express device to the specified policy. |
| 88 | */ |
| 89 | static int pci_mps_set(int policy) |
| 90 | { |
| 91 | struct udevice *bus; |
| 92 | int i, res = 0; |
| 93 | /* 0 = 128B, min value for hotplug */ |
| 94 | unsigned int mps = 0; |
| 95 | |
| 96 | if (policy == PCI_MPS_SAFE) { |
| 97 | unsigned int min_mps = PCI_EXP_DEVCAP_PAYLOAD_4096B, n = 0; |
| 98 | |
| 99 | /* Find maximum MPS supported by all devices */ |
| 100 | for (i = 0; |
| 101 | uclass_get_device_by_seq(UCLASS_PCI, i, &bus) == 0 && |
| 102 | res == 0; |
| 103 | i++) |
| 104 | res = pci_mps_find_safe(bus, &min_mps, &n); |
| 105 | |
| 106 | /* If no devices were found, do not reconfigure */ |
| 107 | if (n == 0) |
| 108 | return res; |
| 109 | mps = min_mps; |
| 110 | } |
| 111 | |
| 112 | /* This message is checked by the sandbox test */ |
| 113 | printf("Setting MPS of all devices to %uB\n", 128U << mps); |
| 114 | for (i = 0; |
| 115 | uclass_get_device_by_seq(UCLASS_PCI, i, &bus) == 0 && res == 0; |
| 116 | i++) |
| 117 | res = pci_mps_set_bus(bus, mps); |
| 118 | |
| 119 | return res; |
| 120 | } |
| 121 | |
| 122 | /* |
| 123 | * PCI MPS tuning commands |
| 124 | * |
| 125 | * Syntax: |
| 126 | * pci_mps safe |
| 127 | * pci_mps peer2peer |
| 128 | */ |
| 129 | static int do_pci_mps(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[]) |
| 130 | { |
| 131 | char cmd = 'u'; |
| 132 | int ret = 0; |
| 133 | |
| 134 | if (argc > 1) |
| 135 | cmd = argv[1][0]; |
| 136 | |
| 137 | switch (cmd) { |
| 138 | case 's': /* safe */ |
| 139 | ret = pci_mps_set(PCI_MPS_SAFE); |
| 140 | break; |
| 141 | case 'p': /* peer2peer/hotplug */ |
| 142 | ret = pci_mps_set(PCI_MPS_PEER2PEER); |
| 143 | break; |
| 144 | default: /* usage, help */ |
| 145 | goto usage; |
| 146 | } |
| 147 | |
| 148 | return ret; |
| 149 | usage: |
| 150 | return CMD_RET_USAGE; |
| 151 | } |
| 152 | |
| 153 | /***************************************************/ |
| 154 | |
| 155 | #ifdef CONFIG_SYS_LONGHELP |
| 156 | static char pci_mps_help_text[] = |
| 157 | "safe\n" |
| 158 | " - Set PCI Express MPS of all devices to safe values\n" |
| 159 | "pci_mps peer2peer\n" |
| 160 | " - Set PCI Express MPS of all devices to support hotplug and peer-to-peer DMA\n"; |
| 161 | #endif |
| 162 | |
| 163 | U_BOOT_CMD(pci_mps, 2, 0, do_pci_mps, |
| 164 | "configure PCI Express MPS", pci_mps_help_text); |