diff options
Diffstat (limited to 'cmd/pci_mps.c')
| -rw-r--r-- | cmd/pci_mps.c | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/cmd/pci_mps.c b/cmd/pci_mps.c new file mode 100644 index 00000000000..555a5fdd8e6 --- /dev/null +++ b/cmd/pci_mps.c @@ -0,0 +1,164 @@ +// 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 <common.h> +#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; +} + +/***************************************************/ + +#ifdef CONFIG_SYS_LONGHELP +static char pci_mps_help_text[] = + "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"; +#endif + +U_BOOT_CMD(pci_mps, 2, 0, do_pci_mps, + "configure PCI Express MPS", pci_mps_help_text); |