@@ -69,6 +69,18 @@ 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
@@ -27,6 +27,8 @@ 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
new file mode 100644
@@ -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 <andriy.shevchenko@linux.intel.com>
+ * Jonathan Yong <jonathan.yong@intel.com>
+ */
+
+#include <linux/bits.h>
+#include <linux/export.h>
+#include <linux/pci.h>
+#include <linux/platform_data/x86/p2sb.h>
+
+#include <asm/cpu_device_id.h>
+#include <asm/intel-family.h>
+
+#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);
new file mode 100644
@@ -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 <linux/errno.h>
+#include <linux/kconfig.h>
+
+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 */