diff options
Diffstat (limited to 'drivers/pci/tph.c')
| -rw-r--r-- | drivers/pci/tph.c | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/drivers/pci/tph.c b/drivers/pci/tph.c new file mode 100644 index 000000000000..4d6317cbf8a6 --- /dev/null +++ b/drivers/pci/tph.c @@ -0,0 +1,197 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * TPH (TLP Processing Hints) support + * + * Copyright (C) 2024 Advanced Micro Devices, Inc. + * Eric Van Tassell <Eric.VanTassell@amd.com> + * Wei Huang <wei.huang2@amd.com> + */ +#include <linux/pci.h> +#include <linux/bitfield.h> +#include <linux/pci-tph.h> + +#include "pci.h" + +/* System-wide TPH disabled */ +static bool pci_tph_disabled; + +static u8 get_st_modes(struct pci_dev *pdev) +{ + u32 reg; + + pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CAP, ®); + reg &= PCI_TPH_CAP_ST_NS | PCI_TPH_CAP_ST_IV | PCI_TPH_CAP_ST_DS; + + return reg; +} + +/* Return device's Root Port completer capability */ +static u8 get_rp_completer_type(struct pci_dev *pdev) +{ + struct pci_dev *rp; + u32 reg; + int ret; + + rp = pcie_find_root_port(pdev); + if (!rp) + return 0; + + ret = pcie_capability_read_dword(rp, PCI_EXP_DEVCAP2, ®); + if (ret) + return 0; + + return FIELD_GET(PCI_EXP_DEVCAP2_TPH_COMP_MASK, reg); +} + +/** + * pcie_disable_tph - Turn off TPH support for device + * @pdev: PCI device + * + * Return: none + */ +void pcie_disable_tph(struct pci_dev *pdev) +{ + if (!pdev->tph_cap) + return; + + if (!pdev->tph_enabled) + return; + + pci_write_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, 0); + + pdev->tph_mode = 0; + pdev->tph_req_type = 0; + pdev->tph_enabled = 0; +} +EXPORT_SYMBOL(pcie_disable_tph); + +/** + * pcie_enable_tph - Enable TPH support for device using a specific ST mode + * @pdev: PCI device + * @mode: ST mode to enable. Current supported modes include: + * + * - PCI_TPH_ST_NS_MODE: NO ST Mode + * - PCI_TPH_ST_IV_MODE: Interrupt Vector Mode + * - PCI_TPH_ST_DS_MODE: Device Specific Mode + * + * Check whether the mode is actually supported by the device before enabling + * and return an error if not. Additionally determine what types of requests, + * TPH or extended TPH, can be issued by the device based on its TPH requester + * capability and the Root Port's completer capability. + * + * Return: 0 on success, otherwise negative value (-errno) + */ +int pcie_enable_tph(struct pci_dev *pdev, int mode) +{ + u32 reg; + u8 dev_modes; + u8 rp_req_type; + + /* Honor "notph" kernel parameter */ + if (pci_tph_disabled) + return -EINVAL; + + if (!pdev->tph_cap) + return -EINVAL; + + if (pdev->tph_enabled) + return -EBUSY; + + /* Sanitize and check ST mode compatibility */ + mode &= PCI_TPH_CTRL_MODE_SEL_MASK; + dev_modes = get_st_modes(pdev); + if (!((1 << mode) & dev_modes)) + return -EINVAL; + + pdev->tph_mode = mode; + + /* Get req_type supported by device and its Root Port */ + pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CAP, ®); + if (FIELD_GET(PCI_TPH_CAP_EXT_TPH, reg)) + pdev->tph_req_type = PCI_TPH_REQ_EXT_TPH; + else + pdev->tph_req_type = PCI_TPH_REQ_TPH_ONLY; + + rp_req_type = get_rp_completer_type(pdev); + + /* Final req_type is the smallest value of two */ + pdev->tph_req_type = min(pdev->tph_req_type, rp_req_type); + + if (pdev->tph_req_type == PCI_TPH_REQ_DISABLE) + return -EINVAL; + + /* Write them into TPH control register */ + pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, ®); + + reg &= ~PCI_TPH_CTRL_MODE_SEL_MASK; + reg |= FIELD_PREP(PCI_TPH_CTRL_MODE_SEL_MASK, pdev->tph_mode); + + reg &= ~PCI_TPH_CTRL_REQ_EN_MASK; + reg |= FIELD_PREP(PCI_TPH_CTRL_REQ_EN_MASK, pdev->tph_req_type); + + pci_write_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, reg); + + pdev->tph_enabled = 1; + + return 0; +} +EXPORT_SYMBOL(pcie_enable_tph); + +void pci_restore_tph_state(struct pci_dev *pdev) +{ + struct pci_cap_saved_state *save_state; + u32 *cap; + + if (!pdev->tph_cap) + return; + + if (!pdev->tph_enabled) + return; + + save_state = pci_find_saved_ext_cap(pdev, PCI_EXT_CAP_ID_TPH); + if (!save_state) + return; + + /* Restore control register and all ST entries */ + cap = &save_state->cap.data[0]; + pci_write_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, *cap++); +} + +void pci_save_tph_state(struct pci_dev *pdev) +{ + struct pci_cap_saved_state *save_state; + u32 *cap; + + if (!pdev->tph_cap) + return; + + if (!pdev->tph_enabled) + return; + + save_state = pci_find_saved_ext_cap(pdev, PCI_EXT_CAP_ID_TPH); + if (!save_state) + return; + + /* Save control register */ + cap = &save_state->cap.data[0]; + pci_read_config_dword(pdev, pdev->tph_cap + PCI_TPH_CTRL, cap++); +} + +void pci_no_tph(void) +{ + pci_tph_disabled = true; + + pr_info("PCIe TPH is disabled\n"); +} + +void pci_tph_init(struct pci_dev *pdev) +{ + u32 save_size; + + pdev->tph_cap = pci_find_ext_capability(pdev, PCI_EXT_CAP_ID_TPH); + if (!pdev->tph_cap) + return; + + save_size = sizeof(u32); + pci_add_ext_cap_save_buffer(pdev, PCI_EXT_CAP_ID_TPH, save_size); +} |