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kernel/drivers/pci/pci-bridge-emul.c

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2018 Marvell
*
* Author: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
*
* This file helps PCI controller drivers implement a fake root port
* PCI bridge when the HW doesn't provide such a root port PCI
* bridge.
*
* It emulates a PCI bridge by providing a fake PCI configuration
* space (and optionally a PCIe capability configuration space) in
* memory. By default the read/write operations simply read and update
* this fake configuration space in memory. However, PCI controller
* drivers can provide through the 'struct pci_sw_bridge_ops'
* structure a set of operations to override or complement this
* default behavior.
*/
#include <linux/pci.h>
#include "pci-bridge-emul.h"
#define PCI_BRIDGE_CONF_END PCI_STD_HEADER_SIZEOF
#define PCI_CAP_SSID_SIZEOF (PCI_SSVID_DEVICE_ID + 2)
#define PCI_CAP_PCIE_SIZEOF (PCI_EXP_SLTSTA2 + 2)
/**
* struct pci_bridge_reg_behavior - register bits behaviors
* @ro: Read-Only bits
* @rw: Read-Write bits
* @w1c: Write-1-to-Clear bits
*
* Reads and Writes will be filtered by specified behavior. All other bits not
* declared are assumed 'Reserved' and will return 0 on reads, per PCIe 5.0:
* "Reserved register fields must be read only and must return 0 (all 0's for
* multi-bit fields) when read".
*/
struct pci_bridge_reg_behavior {
/* Read-only bits */
u32 ro;
/* Read-write bits */
u32 rw;
/* Write-1-to-clear bits */
u32 w1c;
};
static const
struct pci_bridge_reg_behavior pci_regs_behavior[PCI_STD_HEADER_SIZEOF / 4] = {
[PCI_VENDOR_ID / 4] = { .ro = ~0 },
[PCI_COMMAND / 4] = {
.rw = (PCI_COMMAND_IO | PCI_COMMAND_MEMORY |
PCI_COMMAND_MASTER | PCI_COMMAND_PARITY |
PCI_COMMAND_SERR),
.ro = ((PCI_COMMAND_SPECIAL | PCI_COMMAND_INVALIDATE |
PCI_COMMAND_VGA_PALETTE | PCI_COMMAND_WAIT |
PCI_COMMAND_FAST_BACK) |
(PCI_STATUS_CAP_LIST | PCI_STATUS_66MHZ |
PCI_STATUS_FAST_BACK | PCI_STATUS_DEVSEL_MASK) << 16),
.w1c = PCI_STATUS_ERROR_BITS << 16,
},
[PCI_CLASS_REVISION / 4] = { .ro = ~0 },
/*
* Cache Line Size register: implement as read-only, we do not
* pretend implementing "Memory Write and Invalidate"
* transactions"
*
* Latency Timer Register: implemented as read-only, as "A
* bridge that is not capable of a burst transfer of more than
* two data phases on its primary interface is permitted to
* hardwire the Latency Timer to a value of 16 or less"
*
* Header Type: always read-only
*
* BIST register: implemented as read-only, as "A bridge that
* does not support BIST must implement this register as a
* read-only register that returns 0 when read"
*/
[PCI_CACHE_LINE_SIZE / 4] = { .ro = ~0 },
/*
* Base Address registers not used must be implemented as
* read-only registers that return 0 when read.
*/
[PCI_BASE_ADDRESS_0 / 4] = { .ro = ~0 },
[PCI_BASE_ADDRESS_1 / 4] = { .ro = ~0 },
[PCI_PRIMARY_BUS / 4] = {
/* Primary, secondary and subordinate bus are RW */
.rw = GENMASK(24, 0),
/* Secondary latency is read-only */
.ro = GENMASK(31, 24),
},
[PCI_IO_BASE / 4] = {
/* The high four bits of I/O base/limit are RW */
.rw = (GENMASK(15, 12) | GENMASK(7, 4)),
/* The low four bits of I/O base/limit are RO */
.ro = (((PCI_STATUS_66MHZ | PCI_STATUS_FAST_BACK |
PCI_STATUS_DEVSEL_MASK) << 16) |
GENMASK(11, 8) | GENMASK(3, 0)),
.w1c = PCI_STATUS_ERROR_BITS << 16,
},
[PCI_MEMORY_BASE / 4] = {
/* The high 12-bits of mem base/limit are RW */
.rw = GENMASK(31, 20) | GENMASK(15, 4),
/* The low four bits of mem base/limit are RO */
.ro = GENMASK(19, 16) | GENMASK(3, 0),
},
[PCI_PREF_MEMORY_BASE / 4] = {
/* The high 12-bits of pref mem base/limit are RW */
.rw = GENMASK(31, 20) | GENMASK(15, 4),
/* The low four bits of pref mem base/limit are RO */
.ro = GENMASK(19, 16) | GENMASK(3, 0),
},
[PCI_PREF_BASE_UPPER32 / 4] = {
.rw = ~0,
},
[PCI_PREF_LIMIT_UPPER32 / 4] = {
.rw = ~0,
},
[PCI_IO_BASE_UPPER16 / 4] = {
.rw = ~0,
},
[PCI_CAPABILITY_LIST / 4] = {
.ro = GENMASK(7, 0),
},
/*
* If expansion ROM is unsupported then ROM Base Address register must
* be implemented as read-only register that return 0 when read, same
* as for unused Base Address registers.
*/
[PCI_ROM_ADDRESS1 / 4] = {
.ro = ~0,
},
/*
* Interrupt line (bits 7:0) are RW, interrupt pin (bits 15:8)
* are RO, and bridge control (31:16) are a mix of RW, RO,
* reserved and W1C bits
*/
[PCI_INTERRUPT_LINE / 4] = {
/* Interrupt line is RW */
.rw = (GENMASK(7, 0) |
((PCI_BRIDGE_CTL_PARITY |
PCI_BRIDGE_CTL_SERR |
PCI_BRIDGE_CTL_ISA |
PCI_BRIDGE_CTL_VGA |
PCI_BRIDGE_CTL_MASTER_ABORT |
PCI_BRIDGE_CTL_BUS_RESET |
BIT(8) | BIT(9) | BIT(11)) << 16)),
/* Interrupt pin is RO */
.ro = (GENMASK(15, 8) | ((PCI_BRIDGE_CTL_FAST_BACK) << 16)),
.w1c = BIT(10) << 16,
},
};
static const
struct pci_bridge_reg_behavior pcie_cap_regs_behavior[PCI_CAP_PCIE_SIZEOF / 4] = {
[PCI_CAP_LIST_ID / 4] = {
/*
* Capability ID, Next Capability Pointer and
* bits [14:0] of Capabilities register are all read-only.
* Bit 15 of Capabilities register is reserved.
*/
.ro = GENMASK(30, 0),
},
[PCI_EXP_DEVCAP / 4] = {
/*
* Bits [31:29] and [17:16] are reserved.
* Bits [27:18] are reserved for non-upstream ports.
* Bits 28 and [14:6] are reserved for non-endpoint devices.
* Other bits are read-only.
*/
.ro = BIT(15) | GENMASK(5, 0),
},
[PCI_EXP_DEVCTL / 4] = {
/*
* Device control register is RW, except bit 15 which is
* reserved for non-endpoints or non-PCIe-to-PCI/X bridges.
*/
.rw = GENMASK(14, 0),
/*
* Device status register has bits 6 and [3:0] W1C, [5:4] RO,
* the rest is reserved. Also bit 6 is reserved for non-upstream
* ports.
*/
.w1c = GENMASK(3, 0) << 16,
.ro = GENMASK(5, 4) << 16,
},
[PCI_EXP_LNKCAP / 4] = {
/*
* All bits are RO, except bit 23 which is reserved and
* bit 18 which is reserved for non-upstream ports.
*/
.ro = lower_32_bits(~(BIT(23) | PCI_EXP_LNKCAP_CLKPM)),
},
[PCI_EXP_LNKCTL / 4] = {
/*
* Link control has bits [15:14], [11:3] and [1:0] RW, the
* rest is reserved. Bit 8 is reserved for non-upstream ports.
*
* Link status has bits [13:0] RO, and bits [15:14]
* W1C.
*/
.rw = GENMASK(15, 14) | GENMASK(11, 9) | GENMASK(7, 3) | GENMASK(1, 0),
.ro = GENMASK(13, 0) << 16,
.w1c = GENMASK(15, 14) << 16,
},
[PCI_EXP_SLTCAP / 4] = {
.ro = ~0,
},
[PCI_EXP_SLTCTL / 4] = {
/*
* Slot control has bits [14:0] RW, the rest is
* reserved.
*
* Slot status has bits 8 and [4:0] W1C, bits [7:5] RO, the
* rest is reserved.
*/
.rw = GENMASK(14, 0),
.w1c = (PCI_EXP_SLTSTA_ABP | PCI_EXP_SLTSTA_PFD |
PCI_EXP_SLTSTA_MRLSC | PCI_EXP_SLTSTA_PDC |
PCI_EXP_SLTSTA_CC | PCI_EXP_SLTSTA_DLLSC) << 16,
.ro = (PCI_EXP_SLTSTA_MRLSS | PCI_EXP_SLTSTA_PDS |
PCI_EXP_SLTSTA_EIS) << 16,
},
[PCI_EXP_RTCTL / 4] = {
/*
* Root control has bits [4:0] RW, the rest is
* reserved.
*
* Root capabilities has bit 0 RO, the rest is reserved.
*/
.rw = (PCI_EXP_RTCTL_SECEE | PCI_EXP_RTCTL_SENFEE |
PCI_EXP_RTCTL_SEFEE | PCI_EXP_RTCTL_PMEIE |
PCI_EXP_RTCTL_CRSSVE),
.ro = PCI_EXP_RTCAP_CRSVIS << 16,
},
[PCI_EXP_RTSTA / 4] = {
/*
* Root status has bits 17 and [15:0] RO, bit 16 W1C, the rest
* is reserved.
*/
.ro = GENMASK(15, 0) | PCI_EXP_RTSTA_PENDING,
.w1c = PCI_EXP_RTSTA_PME,
},
[PCI_EXP_DEVCAP2 / 4] = {
/*
* Device capabilities 2 register has reserved bits [30:27].
* Also bits [26:24] are reserved for non-upstream ports.
*/
.ro = BIT(31) | GENMASK(23, 0),
},
[PCI_EXP_DEVCTL2 / 4] = {
/*
* Device control 2 register is RW. Bit 11 is reserved for
* non-upstream ports.
*
* Device status 2 register is reserved.
*/
.rw = GENMASK(15, 12) | GENMASK(10, 0),
},
[PCI_EXP_LNKCAP2 / 4] = {
/* Link capabilities 2 register has reserved bits [30:25] and 0. */
.ro = BIT(31) | GENMASK(24, 1),
},
[PCI_EXP_LNKCTL2 / 4] = {
/*
* Link control 2 register is RW.
*
* Link status 2 register has bits 5, 15 W1C;
* bits 10, 11 reserved and others are RO.
*/
.rw = GENMASK(15, 0),
.w1c = (BIT(15) | BIT(5)) << 16,
.ro = (GENMASK(14, 12) | GENMASK(9, 6) | GENMASK(4, 0)) << 16,
},
[PCI_EXP_SLTCAP2 / 4] = {
/* Slot capabilities 2 register is reserved. */
},
[PCI_EXP_SLTCTL2 / 4] = {
/* Both Slot control 2 and Slot status 2 registers are reserved. */
},
};
static pci_bridge_emul_read_status_t
pci_bridge_emul_read_ssid(struct pci_bridge_emul *bridge, int reg, u32 *value)
{
switch (reg) {
case PCI_CAP_LIST_ID:
*value = PCI_CAP_ID_SSVID |
((bridge->pcie_start > bridge->ssid_start) ? (bridge->pcie_start << 8) : 0);
return PCI_BRIDGE_EMUL_HANDLED;
case PCI_SSVID_VENDOR_ID:
*value = bridge->subsystem_vendor_id |
(bridge->subsystem_id << 16);
return PCI_BRIDGE_EMUL_HANDLED;
default:
return PCI_BRIDGE_EMUL_NOT_HANDLED;
}
}
/*
* Initialize a pci_bridge_emul structure to represent a fake PCI
* bridge configuration space. The caller needs to have initialized
* the PCI configuration space with whatever values make sense
* (typically at least vendor, device, revision), the ->ops pointer,
* and optionally ->data and ->has_pcie.
*/
int pci_bridge_emul_init(struct pci_bridge_emul *bridge,
unsigned int flags)
{
BUILD_BUG_ON(sizeof(bridge->conf) != PCI_BRIDGE_CONF_END);
/*
* class_revision: Class is high 24 bits and revision is low 8 bit
* of this member, while class for PCI Bridge Normal Decode has the
* 24-bit value: PCI_CLASS_BRIDGE_PCI_NORMAL
*/
bridge->conf.class_revision |=
cpu_to_le32(PCI_CLASS_BRIDGE_PCI_NORMAL << 8);
bridge->conf.header_type = PCI_HEADER_TYPE_BRIDGE;
bridge->conf.cache_line_size = 0x10;
bridge->conf.status = cpu_to_le16(PCI_STATUS_CAP_LIST);
bridge->pci_regs_behavior = kmemdup(pci_regs_behavior,
sizeof(pci_regs_behavior),
GFP_KERNEL);
if (!bridge->pci_regs_behavior)
return -ENOMEM;
/* If ssid_start and pcie_start were not specified then choose the lowest possible value. */
if (!bridge->ssid_start && !bridge->pcie_start) {
if (bridge->subsystem_vendor_id)
bridge->ssid_start = PCI_BRIDGE_CONF_END;
if (bridge->has_pcie)
bridge->pcie_start = bridge->ssid_start + PCI_CAP_SSID_SIZEOF;
} else if (!bridge->ssid_start && bridge->subsystem_vendor_id) {
if (bridge->pcie_start - PCI_BRIDGE_CONF_END >= PCI_CAP_SSID_SIZEOF)
bridge->ssid_start = PCI_BRIDGE_CONF_END;
else
bridge->ssid_start = bridge->pcie_start + PCI_CAP_PCIE_SIZEOF;
} else if (!bridge->pcie_start && bridge->has_pcie) {
if (bridge->ssid_start - PCI_BRIDGE_CONF_END >= PCI_CAP_PCIE_SIZEOF)
bridge->pcie_start = PCI_BRIDGE_CONF_END;
else
bridge->pcie_start = bridge->ssid_start + PCI_CAP_SSID_SIZEOF;
}
bridge->conf.capabilities_pointer = min(bridge->ssid_start, bridge->pcie_start);
if (bridge->conf.capabilities_pointer)
bridge->conf.status |= cpu_to_le16(PCI_STATUS_CAP_LIST);
if (bridge->has_pcie) {
bridge->pcie_conf.cap_id = PCI_CAP_ID_EXP;
bridge->pcie_conf.next = (bridge->ssid_start > bridge->pcie_start) ?
bridge->ssid_start : 0;
bridge->pcie_conf.cap |= cpu_to_le16(PCI_EXP_TYPE_ROOT_PORT << 4);
bridge->pcie_cap_regs_behavior =
kmemdup(pcie_cap_regs_behavior,
sizeof(pcie_cap_regs_behavior),
GFP_KERNEL);
if (!bridge->pcie_cap_regs_behavior) {
kfree(bridge->pci_regs_behavior);
return -ENOMEM;
}
/* These bits are applicable only for PCI and reserved on PCIe */
bridge->pci_regs_behavior[PCI_CACHE_LINE_SIZE / 4].ro &=
~GENMASK(15, 8);
bridge->pci_regs_behavior[PCI_COMMAND / 4].ro &=
~((PCI_COMMAND_SPECIAL | PCI_COMMAND_INVALIDATE |
PCI_COMMAND_VGA_PALETTE | PCI_COMMAND_WAIT |
PCI_COMMAND_FAST_BACK) |
(PCI_STATUS_66MHZ | PCI_STATUS_FAST_BACK |
PCI_STATUS_DEVSEL_MASK) << 16);
bridge->pci_regs_behavior[PCI_PRIMARY_BUS / 4].ro &=
~GENMASK(31, 24);
bridge->pci_regs_behavior[PCI_IO_BASE / 4].ro &=
~((PCI_STATUS_66MHZ | PCI_STATUS_FAST_BACK |
PCI_STATUS_DEVSEL_MASK) << 16);
bridge->pci_regs_behavior[PCI_INTERRUPT_LINE / 4].rw &=
~((PCI_BRIDGE_CTL_MASTER_ABORT |
BIT(8) | BIT(9) | BIT(11)) << 16);
bridge->pci_regs_behavior[PCI_INTERRUPT_LINE / 4].ro &=
~((PCI_BRIDGE_CTL_FAST_BACK) << 16);
bridge->pci_regs_behavior[PCI_INTERRUPT_LINE / 4].w1c &=
~(BIT(10) << 16);
}
if (flags & PCI_BRIDGE_EMUL_NO_PREFMEM_FORWARD) {
bridge->pci_regs_behavior[PCI_PREF_MEMORY_BASE / 4].ro = ~0;
bridge->pci_regs_behavior[PCI_PREF_MEMORY_BASE / 4].rw = 0;
}
if (flags & PCI_BRIDGE_EMUL_NO_IO_FORWARD) {
bridge->pci_regs_behavior[PCI_COMMAND / 4].ro |= PCI_COMMAND_IO;
bridge->pci_regs_behavior[PCI_COMMAND / 4].rw &= ~PCI_COMMAND_IO;
bridge->pci_regs_behavior[PCI_IO_BASE / 4].ro |= GENMASK(15, 0);
bridge->pci_regs_behavior[PCI_IO_BASE / 4].rw &= ~GENMASK(15, 0);
bridge->pci_regs_behavior[PCI_IO_BASE_UPPER16 / 4].ro = ~0;
bridge->pci_regs_behavior[PCI_IO_BASE_UPPER16 / 4].rw = 0;
}
return 0;
}
EXPORT_SYMBOL_GPL(pci_bridge_emul_init);
/*
* Cleanup a pci_bridge_emul structure that was previously initialized
* using pci_bridge_emul_init().
*/
void pci_bridge_emul_cleanup(struct pci_bridge_emul *bridge)
{
if (bridge->has_pcie)
kfree(bridge->pcie_cap_regs_behavior);
kfree(bridge->pci_regs_behavior);
}
EXPORT_SYMBOL_GPL(pci_bridge_emul_cleanup);
/*
* Should be called by the PCI controller driver when reading the PCI
* configuration space of the fake bridge. It will call back the
* ->ops->read_base or ->ops->read_pcie operations.
*/
int pci_bridge_emul_conf_read(struct pci_bridge_emul *bridge, int where,
int size, u32 *value)
{
int ret;
int reg = where & ~3;
pci_bridge_emul_read_status_t (*read_op)(struct pci_bridge_emul *bridge,
int reg, u32 *value);
__le32 *cfgspace;
const struct pci_bridge_reg_behavior *behavior;
if (reg < PCI_BRIDGE_CONF_END) {
/* Emulated PCI space */
read_op = bridge->ops->read_base;
cfgspace = (__le32 *) &bridge->conf;
behavior = bridge->pci_regs_behavior;
} else if (reg >= bridge->ssid_start && reg < bridge->ssid_start + PCI_CAP_SSID_SIZEOF &&
bridge->subsystem_vendor_id) {
/* Emulated PCI Bridge Subsystem Vendor ID capability */
reg -= bridge->ssid_start;
read_op = pci_bridge_emul_read_ssid;
cfgspace = NULL;
behavior = NULL;
} else if (reg >= bridge->pcie_start && reg < bridge->pcie_start + PCI_CAP_PCIE_SIZEOF &&
bridge->has_pcie) {
/* Our emulated PCIe capability */
reg -= bridge->pcie_start;
read_op = bridge->ops->read_pcie;
cfgspace = (__le32 *) &bridge->pcie_conf;
behavior = bridge->pcie_cap_regs_behavior;
} else if (reg >= PCI_CFG_SPACE_SIZE && bridge->has_pcie) {
/* PCIe extended capability space */
reg -= PCI_CFG_SPACE_SIZE;
read_op = bridge->ops->read_ext;
cfgspace = NULL;
behavior = NULL;
} else {
/* Not implemented */
*value = 0;
return PCIBIOS_SUCCESSFUL;
}
if (read_op)
ret = read_op(bridge, reg, value);
else
ret = PCI_BRIDGE_EMUL_NOT_HANDLED;
if (ret == PCI_BRIDGE_EMUL_NOT_HANDLED) {
if (cfgspace)
*value = le32_to_cpu(cfgspace[reg / 4]);
else
*value = 0;
}
/*
* Make sure we never return any reserved bit with a value
* different from 0.
*/
if (behavior)
*value &= behavior[reg / 4].ro | behavior[reg / 4].rw |
behavior[reg / 4].w1c;
if (size == 1)
*value = (*value >> (8 * (where & 3))) & 0xff;
else if (size == 2)
*value = (*value >> (8 * (where & 3))) & 0xffff;
else if (size != 4)
return PCIBIOS_BAD_REGISTER_NUMBER;
return PCIBIOS_SUCCESSFUL;
}
EXPORT_SYMBOL_GPL(pci_bridge_emul_conf_read);
/*
* Should be called by the PCI controller driver when writing the PCI
* configuration space of the fake bridge. It will call back the
* ->ops->write_base or ->ops->write_pcie operations.
*/
int pci_bridge_emul_conf_write(struct pci_bridge_emul *bridge, int where,
int size, u32 value)
{
int reg = where & ~3;
int mask, ret, old, new, shift;
void (*write_op)(struct pci_bridge_emul *bridge, int reg,
u32 old, u32 new, u32 mask);
__le32 *cfgspace;
const struct pci_bridge_reg_behavior *behavior;
ret = pci_bridge_emul_conf_read(bridge, reg, 4, &old);
if (ret != PCIBIOS_SUCCESSFUL)
return ret;
if (reg < PCI_BRIDGE_CONF_END) {
/* Emulated PCI space */
write_op = bridge->ops->write_base;
cfgspace = (__le32 *) &bridge->conf;
behavior = bridge->pci_regs_behavior;
} else if (reg >= bridge->pcie_start && reg < bridge->pcie_start + PCI_CAP_PCIE_SIZEOF &&
bridge->has_pcie) {
/* Our emulated PCIe capability */
reg -= bridge->pcie_start;
write_op = bridge->ops->write_pcie;
cfgspace = (__le32 *) &bridge->pcie_conf;
behavior = bridge->pcie_cap_regs_behavior;
} else if (reg >= PCI_CFG_SPACE_SIZE && bridge->has_pcie) {
/* PCIe extended capability space */
reg -= PCI_CFG_SPACE_SIZE;
write_op = bridge->ops->write_ext;
cfgspace = NULL;
behavior = NULL;
} else {
/* Not implemented */
return PCIBIOS_SUCCESSFUL;
}
shift = (where & 0x3) * 8;
if (size == 4)
mask = 0xffffffff;
else if (size == 2)
mask = 0xffff << shift;
else if (size == 1)
mask = 0xff << shift;
else
return PCIBIOS_BAD_REGISTER_NUMBER;
if (behavior) {
/* Keep all bits, except the RW bits */
new = old & (~mask | ~behavior[reg / 4].rw);
/* Update the value of the RW bits */
new |= (value << shift) & (behavior[reg / 4].rw & mask);
/* Clear the W1C bits */
new &= ~((value << shift) & (behavior[reg / 4].w1c & mask));
} else {
new = old & ~mask;
new |= (value << shift) & mask;
}
if (cfgspace) {
/* Save the new value with the cleared W1C bits into the cfgspace */
cfgspace[reg / 4] = cpu_to_le32(new);
}
if (behavior) {
/*
* Clear the W1C bits not specified by the write mask, so that the
* write_op() does not clear them.
*/
new &= ~(behavior[reg / 4].w1c & ~mask);
/*
* Set the W1C bits specified by the write mask, so that write_op()
* knows about that they are to be cleared.
*/
new |= (value << shift) & (behavior[reg / 4].w1c & mask);
}
if (write_op)
write_op(bridge, reg, old, new, mask);
return PCIBIOS_SUCCESSFUL;
}
EXPORT_SYMBOL_GPL(pci_bridge_emul_conf_write);
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