Allow a caller to retrieve Steering Tags for a target memory that is associated with a specific CPU. The caller must provided two parameters, memory type and CPU UID, when calling this function. The tag is retrieved by invoking ACPI _DSM of the device's Root Port device. Co-developed-by: Eric Van Tassell <Eric.VanTassell@xxxxxxx> Signed-off-by: Eric Van Tassell <Eric.VanTassell@xxxxxxx> Signed-off-by: Wei Huang <wei.huang2@xxxxxxx> Reviewed-by: Ajit Khaparde <ajit.khaparde@xxxxxxxxxxxx> Reviewed-by: Somnath Kotur <somnath.kotur@xxxxxxxxxxxx> Reviewed-by: Andy Gospodarek <andrew.gospodarek@xxxxxxxxxxxx> --- drivers/pci/pcie/tph.c | 154 ++++++++++++++++++++++++++++++++++++++++ include/linux/pci-tph.h | 18 +++++ 2 files changed, 172 insertions(+) diff --git a/drivers/pci/pcie/tph.c b/drivers/pci/pcie/tph.c index 82189361a2ee..5bd194fb425e 100644 --- a/drivers/pci/pcie/tph.c +++ b/drivers/pci/pcie/tph.c @@ -7,12 +7,125 @@ * Wei Huang <wei.huang2@xxxxxxx> */ #include <linux/pci.h> +#include <linux/pci-acpi.h> #include <linux/bitfield.h> #include <linux/msi.h> #include <linux/pci-tph.h> #include "../pci.h" +/* + * The st_info struct defines the Steering Tag (ST) info returned by the + * firmware _DSM method defined in the approved ECN for PCI Firmware Spec, + * available at https://members.pcisig.com/wg/PCI-SIG/document/15470. + * + * @vm_st_valid: 8-bit ST for volatile memory is valid + * @vm_xst_valid: 16-bit extended ST for volatile memory is valid + * @vm_ph_ignore: 1 => PH was and will be ignored, 0 => PH should be supplied + * @vm_st: 8-bit ST for volatile mem + * @vm_xst: 16-bit extended ST for volatile mem + * @pm_st_valid: 8-bit ST for persistent memory is valid + * @pm_xst_valid: 16-bit extended ST for persistent memory is valid + * @pm_ph_ignore: 1 => PH was and will be ignored, 0 => PH should be supplied + * @pm_st: 8-bit ST for persistent mem + * @pm_xst: 16-bit extended ST for persistent mem + */ +union st_info { + struct { + u64 vm_st_valid : 1; + u64 vm_xst_valid : 1; + u64 vm_ph_ignore : 1; + u64 rsvd1 : 5; + u64 vm_st : 8; + u64 vm_xst : 16; + u64 pm_st_valid : 1; + u64 pm_xst_valid : 1; + u64 pm_ph_ignore : 1; + u64 rsvd2 : 5; + u64 pm_st : 8; + u64 pm_xst : 16; + }; + u64 value; +}; + +static u16 tph_extract_tag(enum tph_mem_type mem_type, u8 req_type, + union st_info *info) +{ + switch (req_type) { + case PCI_TPH_REQ_TPH_ONLY: /* 8-bit tag */ + switch (mem_type) { + case TPH_MEM_TYPE_VM: + if (info->vm_st_valid) + return info->vm_st; + break; + case TPH_MEM_TYPE_PM: + if (info->pm_st_valid) + return info->pm_st; + break; + } + break; + case PCI_TPH_REQ_EXT_TPH: /* 16-bit tag */ + switch (mem_type) { + case TPH_MEM_TYPE_VM: + if (info->vm_xst_valid) + return info->vm_xst; + break; + case TPH_MEM_TYPE_PM: + if (info->pm_xst_valid) + return info->pm_xst; + break; + } + break; + default: + return 0; + } + + return 0; +} + +#define TPH_ST_DSM_FUNC_INDEX 0xF +static acpi_status tph_invoke_dsm(acpi_handle handle, u32 cpu_uid, + union st_info *st_out) +{ + union acpi_object arg3[3], in_obj, *out_obj; + + if (!acpi_check_dsm(handle, &pci_acpi_dsm_guid, 7, + BIT(TPH_ST_DSM_FUNC_INDEX))) + return AE_ERROR; + + /* DWORD: feature ID (0 for processor cache ST query) */ + arg3[0].integer.type = ACPI_TYPE_INTEGER; + arg3[0].integer.value = 0; + + /* DWORD: target UID */ + arg3[1].integer.type = ACPI_TYPE_INTEGER; + arg3[1].integer.value = cpu_uid; + + /* QWORD: properties, all 0's */ + arg3[2].integer.type = ACPI_TYPE_INTEGER; + arg3[2].integer.value = 0; + + in_obj.type = ACPI_TYPE_PACKAGE; + in_obj.package.count = ARRAY_SIZE(arg3); + in_obj.package.elements = arg3; + + out_obj = acpi_evaluate_dsm(handle, &pci_acpi_dsm_guid, 7, + TPH_ST_DSM_FUNC_INDEX, &in_obj); + if (!out_obj) + return AE_ERROR; + + if (out_obj->type != ACPI_TYPE_BUFFER) { + ACPI_FREE(out_obj); + return AE_ERROR; + } + + st_out->value = *((u64 *)(out_obj->buffer.pointer)); + + ACPI_FREE(out_obj); + + return AE_OK; +} + /* Update the TPH Requester Enable field of TPH Control Register */ static void set_ctrl_reg_req_en(struct pci_dev *pdev, u8 req_type) { @@ -140,6 +253,47 @@ static int write_tag_to_st_table(struct pci_dev *pdev, int index, u16 tag) return pci_write_config_word(pdev, offset, tag); } +/** + * pcie_tph_get_cpu_st() - Retrieve Steering Tag for a target memory associated + * with a specific CPU + * @pdev: PCI device + * @mem_type: target memory type (volatile or persistent RAM) + * @cpu_uid: associated CPU id + * @tag: Steering Tag to be returned + * + * This function returns the Steering Tag for a target memory that is + * associated with a specific CPU as indicated by cpu_uid. + * + * Returns 0 if success, otherwise negative value (-errno) + */ +int pcie_tph_get_cpu_st(struct pci_dev *pdev, enum tph_mem_type mem_type, + unsigned int cpu_uid, u16 *tag) +{ + struct pci_dev *rp; + acpi_handle rp_acpi_handle; + union st_info info; + + rp = pcie_find_root_port(pdev); + if (!rp || !rp->bus || !rp->bus->bridge) + return -ENODEV; + + rp_acpi_handle = ACPI_HANDLE(rp->bus->bridge); + + if (tph_invoke_dsm(rp_acpi_handle, cpu_uid, &info) != AE_OK) { + *tag = 0; + return -EINVAL; + } + + *tag = tph_extract_tag(mem_type, pdev->tph_req_type, &info); + + pci_dbg(pdev, "get steering tag: mem_type=%s, cpu_uid=%d, tag=%#04x\n", + (mem_type == TPH_MEM_TYPE_VM) ? "volatile" : "persistent", + cpu_uid, *tag); + + return 0; +} +EXPORT_SYMBOL(pcie_tph_get_cpu_st); + /** * pcie_tph_set_st_entry() - Set Steering Tag in the ST table entry * @pdev: PCI device diff --git a/include/linux/pci-tph.h b/include/linux/pci-tph.h index a0c93b97090a..c9f33688b9a9 100644 --- a/include/linux/pci-tph.h +++ b/include/linux/pci-tph.h @@ -9,9 +9,23 @@ #ifndef LINUX_PCI_TPH_H #define LINUX_PCI_TPH_H +/* + * According to the ECN for PCI Firmware Spec, Steering Tag can be different + * depending on the memory type: Volatile Memory or Persistent Memory. When a + * caller query about a target's Steering Tag, it must provide the target's + * tph_mem_type. ECN link: https://members.pcisig.com/wg/PCI-SIG/document/15470. + */ +enum tph_mem_type { + TPH_MEM_TYPE_VM, /* volatile memory */ + TPH_MEM_TYPE_PM /* persistent memory */ +}; + #ifdef CONFIG_PCIE_TPH int pcie_tph_set_st_entry(struct pci_dev *pdev, unsigned int index, u16 tag); +int pcie_tph_get_cpu_st(struct pci_dev *dev, + enum tph_mem_type mem_type, + unsigned int cpu_uid, u16 *tag); bool pcie_tph_enabled(struct pci_dev *pdev); void pcie_disable_tph(struct pci_dev *pdev); int pcie_enable_tph(struct pci_dev *pdev, int mode); @@ -20,6 +34,10 @@ int pcie_tph_modes(struct pci_dev *pdev); static inline int pcie_tph_set_st_entry(struct pci_dev *pdev, unsigned int index, u16 tag) { return -EINVAL; } +static inline int pcie_tph_get_cpu_st(struct pci_dev *dev, + enum tph_mem_type mem_type, + unsigned int cpu_uid, u16 *tag) +{ return -EINVAL; } static inline bool pcie_tph_enabled(struct pci_dev *pdev) { return false; } static inline void pcie_disable_tph(struct pci_dev *pdev) { } static inline int pcie_enable_tph(struct pci_dev *pdev, int mode) -- 2.45.1
