diff --git a/drivers/platform/x86/intel/Kconfig b/drivers/platform/x86/intel/Kconfig index 794968bda115..c9cfbaae436b 100644 --- a/drivers/platform/x86/intel/Kconfig +++ b/drivers/platform/x86/intel/Kconfig @@ -70,6 +70,18 @@ config INTEL_OAKTRAIL enable/disable the Camera, WiFi, BT etc. devices. If in doubt, say Y here; it will only load on supported platforms. +config P2SB + bool "Primary to Sideband (P2SB) bridge access support" + depends on PCI + help + The Primary to Sideband (P2SB) bridge is an interface to some + PCI devices connected through it. In particular, SPI NOR controller + in Intel Apollo Lake SoC is one of such devices. + + The main purpose of this library is to unhide P2SB device in case + firmware kept it hidden on some platforms in order to access devices + behind it. + config INTEL_BXTWC_PMIC_TMU tristate "Intel Broxton Whiskey Cove TMU Driver" depends on INTEL_SOC_PMIC_BXTWC diff --git a/drivers/platform/x86/intel/Makefile b/drivers/platform/x86/intel/Makefile index 717933dd0cfd..741a9404db98 100644 --- a/drivers/platform/x86/intel/Makefile +++ b/drivers/platform/x86/intel/Makefile @@ -28,6 +28,8 @@ intel_int0002_vgpio-y := int0002_vgpio.o obj-$(CONFIG_INTEL_INT0002_VGPIO) += intel_int0002_vgpio.o intel_oaktrail-y := oaktrail.o obj-$(CONFIG_INTEL_OAKTRAIL) += intel_oaktrail.o +intel_p2sb-y := p2sb.o +obj-$(CONFIG_P2SB) += intel_p2sb.o intel_sdsi-y := sdsi.o obj-$(CONFIG_INTEL_SDSI) += intel_sdsi.o intel_vsec-y := vsec.o diff --git a/drivers/platform/x86/intel/p2sb.c b/drivers/platform/x86/intel/p2sb.c new file mode 100644 index 000000000000..b598ef14dbc6 --- /dev/null +++ b/drivers/platform/x86/intel/p2sb.c @@ -0,0 +1,127 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Primary to Sideband (P2SB) bridge access support + * + * Copyright (c) 2017, 2021-2022 Intel Corporation. + * + * Authors: Andy Shevchenko + * Jonathan Yong + */ + +#include +#include +#include +#include + +#include +#include + +#define P2SBC 0xe0 +#define P2SBC_HIDE BIT(8) + +static const struct x86_cpu_id p2sb_cpu_ids[] = { + X86_MATCH_INTEL_FAM6_MODEL(ATOM_GOLDMONT, PCI_DEVFN(13, 0)), + {} +}; + +static int p2sb_get_devfn(unsigned int *devfn) +{ + const struct x86_cpu_id *id; + + id = x86_match_cpu(p2sb_cpu_ids); + if (!id) + return -ENODEV; + + *devfn = (unsigned int)id->driver_data; + return 0; +} + +static int p2sb_read_bar0(struct pci_dev *pdev, struct resource *mem) +{ + /* Copy resource from the first BAR of the device in question */ + *mem = pdev->resource[0]; + return 0; +} + +static int p2sb_scan_and_read(struct pci_bus *bus, unsigned int devfn, struct resource *mem) +{ + struct pci_dev *pdev; + int ret; + + pdev = pci_scan_single_device(bus, devfn); + if (!pdev) + return -ENODEV; + + ret = p2sb_read_bar0(pdev, mem); + + pci_stop_and_remove_bus_device(pdev); + return ret; +} + +/** + * p2sb_bar - Get Primary to Sideband (P2SB) bridge device BAR + * @bus: PCI bus to communicate with + * @devfn: PCI slot and function to communicate with + * @mem: memory resource to be filled in + * + * The BIOS prevents the P2SB device from being enumerated by the PCI + * subsystem, so we need to unhide and hide it back to lookup the BAR. + * + * if @bus is NULL, the bus 0 in domain 0 will be used. + * If @devfn is 0, it will be replaced by devfn of the P2SB device. + * + * Caller must provide a valid pointer to @mem. + * + * Locking is handled by pci_rescan_remove_lock mutex. + * + * Return: + * 0 on success or appropriate errno value on error. + */ +int p2sb_bar(struct pci_bus *bus, unsigned int devfn, struct resource *mem) +{ + struct pci_dev *pdev_p2sb; + unsigned int devfn_p2sb; + u32 value = P2SBC_HIDE; + int ret; + + /* Get devfn for P2SB device itself */ + ret = p2sb_get_devfn(&devfn_p2sb); + if (ret) + return ret; + + /* if @bus is NULL, use bus 0 in domain 0 */ + bus = bus ?: pci_find_bus(0, 0); + + /* + * Prevent concurrent PCI bus scan from seeing the P2SB device and + * removing via sysfs while it is temporarily exposed. + */ + pci_lock_rescan_remove(); + + /* Unhide the P2SB device, if needed */ + pci_bus_read_config_dword(bus, devfn_p2sb, P2SBC, &value); + if (value & P2SBC_HIDE) + pci_bus_write_config_dword(bus, devfn_p2sb, P2SBC, 0); + + pdev_p2sb = pci_scan_single_device(bus, devfn_p2sb); + if (devfn) + ret = p2sb_scan_and_read(bus, devfn, mem); + else + ret = p2sb_read_bar0(pdev_p2sb, mem); + pci_stop_and_remove_bus_device(pdev_p2sb); + + /* Hide the P2SB device, if it was hidden */ + if (value & P2SBC_HIDE) + pci_bus_write_config_dword(bus, devfn_p2sb, P2SBC, P2SBC_HIDE); + + pci_unlock_rescan_remove(); + + if (ret) + return ret; + + if (mem->flags == 0) + return -ENODEV; + + return 0; +} +EXPORT_SYMBOL_GPL(p2sb_bar); diff --git a/include/linux/platform_data/x86/p2sb.h b/include/linux/platform_data/x86/p2sb.h new file mode 100644 index 000000000000..a1d5fddc8f13 --- /dev/null +++ b/include/linux/platform_data/x86/p2sb.h @@ -0,0 +1,28 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Primary to Sideband (P2SB) bridge access support + */ + +#ifndef _PLATFORM_DATA_X86_P2SB_H +#define _PLATFORM_DATA_X86_P2SB_H + +#include +#include + +struct pci_bus; +struct resource; + +#if IS_BUILTIN(CONFIG_P2SB) + +int p2sb_bar(struct pci_bus *bus, unsigned int devfn, struct resource *mem); + +#else /* CONFIG_P2SB */ + +static inline int p2sb_bar(struct pci_bus *bus, unsigned int devfn, struct resource *mem) +{ + return -ENODEV; +} + +#endif /* CONFIG_P2SB is not set */ + +#endif /* _PLATFORM_DATA_X86_P2SB_H */