linux/drivers/cxl/pci.c
Ira Weiny 5e2411ae80 cxl/memdev: Change cxl_mem to a more descriptive name
The 'struct cxl_mem' object actually represents the state of a CXL
device within the driver. Comments indicating that 'struct cxl_mem' is a
device itself are incorrect. It is data layered on top of a CXL Memory
Expander class device. Rename it 'struct cxl_dev_state'. The 'struct'
cxl_memdev' structure represents a Linux CXL memory device object, and
it uses services and information provided by 'struct cxl_dev_state'.

Update the structure name, function names, and the kdocs to reflect the
real uses of this structure.

Some helper functions that were previously prefixed "cxl_mem_" are
renamed to just "cxl_".

Acked-by: Ben Widawsky <ben.widawsky@intel.com>
Signed-off-by: Ira Weiny <ira.weiny@intel.com>
Link: https://lore.kernel.org/r/20211102202901.3675568-3-ira.weiny@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2021-11-15 11:02:58 -08:00

549 lines
15 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/* Copyright(c) 2020 Intel Corporation. All rights reserved. */
#include <linux/io-64-nonatomic-lo-hi.h>
#include <linux/module.h>
#include <linux/sizes.h>
#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/pci.h>
#include <linux/io.h>
#include "cxlmem.h"
#include "pci.h"
#include "cxl.h"
/**
* DOC: cxl pci
*
* This implements the PCI exclusive functionality for a CXL device as it is
* defined by the Compute Express Link specification. CXL devices may surface
* certain functionality even if it isn't CXL enabled. While this driver is
* focused around the PCI specific aspects of a CXL device, it binds to the
* specific CXL memory device class code, and therefore the implementation of
* cxl_pci is focused around CXL memory devices.
*
* The driver has several responsibilities, mainly:
* - Create the memX device and register on the CXL bus.
* - Enumerate device's register interface and map them.
* - Registers nvdimm bridge device with cxl_core.
* - Registers a CXL mailbox with cxl_core.
*/
#define cxl_doorbell_busy(cxlds) \
(readl((cxlds)->regs.mbox + CXLDEV_MBOX_CTRL_OFFSET) & \
CXLDEV_MBOX_CTRL_DOORBELL)
/* CXL 2.0 - 8.2.8.4 */
#define CXL_MAILBOX_TIMEOUT_MS (2 * HZ)
static int cxl_pci_mbox_wait_for_doorbell(struct cxl_dev_state *cxlds)
{
const unsigned long start = jiffies;
unsigned long end = start;
while (cxl_doorbell_busy(cxlds)) {
end = jiffies;
if (time_after(end, start + CXL_MAILBOX_TIMEOUT_MS)) {
/* Check again in case preempted before timeout test */
if (!cxl_doorbell_busy(cxlds))
break;
return -ETIMEDOUT;
}
cpu_relax();
}
dev_dbg(cxlds->dev, "Doorbell wait took %dms",
jiffies_to_msecs(end) - jiffies_to_msecs(start));
return 0;
}
static void cxl_pci_mbox_timeout(struct cxl_dev_state *cxlds,
struct cxl_mbox_cmd *mbox_cmd)
{
struct device *dev = cxlds->dev;
dev_dbg(dev, "Mailbox command (opcode: %#x size: %zub) timed out\n",
mbox_cmd->opcode, mbox_cmd->size_in);
}
/**
* __cxl_pci_mbox_send_cmd() - Execute a mailbox command
* @cxlds: The device state to communicate with.
* @mbox_cmd: Command to send to the memory device.
*
* Context: Any context. Expects mbox_mutex to be held.
* Return: -ETIMEDOUT if timeout occurred waiting for completion. 0 on success.
* Caller should check the return code in @mbox_cmd to make sure it
* succeeded.
*
* This is a generic form of the CXL mailbox send command thus only using the
* registers defined by the mailbox capability ID - CXL 2.0 8.2.8.4. Memory
* devices, and perhaps other types of CXL devices may have further information
* available upon error conditions. Driver facilities wishing to send mailbox
* commands should use the wrapper command.
*
* The CXL spec allows for up to two mailboxes. The intention is for the primary
* mailbox to be OS controlled and the secondary mailbox to be used by system
* firmware. This allows the OS and firmware to communicate with the device and
* not need to coordinate with each other. The driver only uses the primary
* mailbox.
*/
static int __cxl_pci_mbox_send_cmd(struct cxl_dev_state *cxlds,
struct cxl_mbox_cmd *mbox_cmd)
{
void __iomem *payload = cxlds->regs.mbox + CXLDEV_MBOX_PAYLOAD_OFFSET;
struct device *dev = cxlds->dev;
u64 cmd_reg, status_reg;
size_t out_len;
int rc;
lockdep_assert_held(&cxlds->mbox_mutex);
/*
* Here are the steps from 8.2.8.4 of the CXL 2.0 spec.
* 1. Caller reads MB Control Register to verify doorbell is clear
* 2. Caller writes Command Register
* 3. Caller writes Command Payload Registers if input payload is non-empty
* 4. Caller writes MB Control Register to set doorbell
* 5. Caller either polls for doorbell to be clear or waits for interrupt if configured
* 6. Caller reads MB Status Register to fetch Return code
* 7. If command successful, Caller reads Command Register to get Payload Length
* 8. If output payload is non-empty, host reads Command Payload Registers
*
* Hardware is free to do whatever it wants before the doorbell is rung,
* and isn't allowed to change anything after it clears the doorbell. As
* such, steps 2 and 3 can happen in any order, and steps 6, 7, 8 can
* also happen in any order (though some orders might not make sense).
*/
/* #1 */
if (cxl_doorbell_busy(cxlds)) {
dev_err_ratelimited(dev, "Mailbox re-busy after acquiring\n");
return -EBUSY;
}
cmd_reg = FIELD_PREP(CXLDEV_MBOX_CMD_COMMAND_OPCODE_MASK,
mbox_cmd->opcode);
if (mbox_cmd->size_in) {
if (WARN_ON(!mbox_cmd->payload_in))
return -EINVAL;
cmd_reg |= FIELD_PREP(CXLDEV_MBOX_CMD_PAYLOAD_LENGTH_MASK,
mbox_cmd->size_in);
memcpy_toio(payload, mbox_cmd->payload_in, mbox_cmd->size_in);
}
/* #2, #3 */
writeq(cmd_reg, cxlds->regs.mbox + CXLDEV_MBOX_CMD_OFFSET);
/* #4 */
dev_dbg(dev, "Sending command\n");
writel(CXLDEV_MBOX_CTRL_DOORBELL,
cxlds->regs.mbox + CXLDEV_MBOX_CTRL_OFFSET);
/* #5 */
rc = cxl_pci_mbox_wait_for_doorbell(cxlds);
if (rc == -ETIMEDOUT) {
cxl_pci_mbox_timeout(cxlds, mbox_cmd);
return rc;
}
/* #6 */
status_reg = readq(cxlds->regs.mbox + CXLDEV_MBOX_STATUS_OFFSET);
mbox_cmd->return_code =
FIELD_GET(CXLDEV_MBOX_STATUS_RET_CODE_MASK, status_reg);
if (mbox_cmd->return_code != 0) {
dev_dbg(dev, "Mailbox operation had an error\n");
return 0;
}
/* #7 */
cmd_reg = readq(cxlds->regs.mbox + CXLDEV_MBOX_CMD_OFFSET);
out_len = FIELD_GET(CXLDEV_MBOX_CMD_PAYLOAD_LENGTH_MASK, cmd_reg);
/* #8 */
if (out_len && mbox_cmd->payload_out) {
/*
* Sanitize the copy. If hardware misbehaves, out_len per the
* spec can actually be greater than the max allowed size (21
* bits available but spec defined 1M max). The caller also may
* have requested less data than the hardware supplied even
* within spec.
*/
size_t n = min3(mbox_cmd->size_out, cxlds->payload_size, out_len);
memcpy_fromio(mbox_cmd->payload_out, payload, n);
mbox_cmd->size_out = n;
} else {
mbox_cmd->size_out = 0;
}
return 0;
}
/**
* cxl_pci_mbox_get() - Acquire exclusive access to the mailbox.
* @cxlds: The device state to gain access to.
*
* Context: Any context. Takes the mbox_mutex.
* Return: 0 if exclusive access was acquired.
*/
static int cxl_pci_mbox_get(struct cxl_dev_state *cxlds)
{
struct device *dev = cxlds->dev;
u64 md_status;
int rc;
mutex_lock_io(&cxlds->mbox_mutex);
/*
* XXX: There is some amount of ambiguity in the 2.0 version of the spec
* around the mailbox interface ready (8.2.8.5.1.1). The purpose of the
* bit is to allow firmware running on the device to notify the driver
* that it's ready to receive commands. It is unclear if the bit needs
* to be read for each transaction mailbox, ie. the firmware can switch
* it on and off as needed. Second, there is no defined timeout for
* mailbox ready, like there is for the doorbell interface.
*
* Assumptions:
* 1. The firmware might toggle the Mailbox Interface Ready bit, check
* it for every command.
*
* 2. If the doorbell is clear, the firmware should have first set the
* Mailbox Interface Ready bit. Therefore, waiting for the doorbell
* to be ready is sufficient.
*/
rc = cxl_pci_mbox_wait_for_doorbell(cxlds);
if (rc) {
dev_warn(dev, "Mailbox interface not ready\n");
goto out;
}
md_status = readq(cxlds->regs.memdev + CXLMDEV_STATUS_OFFSET);
if (!(md_status & CXLMDEV_MBOX_IF_READY && CXLMDEV_READY(md_status))) {
dev_err(dev, "mbox: reported doorbell ready, but not mbox ready\n");
rc = -EBUSY;
goto out;
}
/*
* Hardware shouldn't allow a ready status but also have failure bits
* set. Spit out an error, this should be a bug report
*/
rc = -EFAULT;
if (md_status & CXLMDEV_DEV_FATAL) {
dev_err(dev, "mbox: reported ready, but fatal\n");
goto out;
}
if (md_status & CXLMDEV_FW_HALT) {
dev_err(dev, "mbox: reported ready, but halted\n");
goto out;
}
if (CXLMDEV_RESET_NEEDED(md_status)) {
dev_err(dev, "mbox: reported ready, but reset needed\n");
goto out;
}
/* with lock held */
return 0;
out:
mutex_unlock(&cxlds->mbox_mutex);
return rc;
}
/**
* cxl_pci_mbox_put() - Release exclusive access to the mailbox.
* @cxlds: The device state to communicate with.
*
* Context: Any context. Expects mbox_mutex to be held.
*/
static void cxl_pci_mbox_put(struct cxl_dev_state *cxlds)
{
mutex_unlock(&cxlds->mbox_mutex);
}
static int cxl_pci_mbox_send(struct cxl_dev_state *cxlds, struct cxl_mbox_cmd *cmd)
{
int rc;
rc = cxl_pci_mbox_get(cxlds);
if (rc)
return rc;
rc = __cxl_pci_mbox_send_cmd(cxlds, cmd);
cxl_pci_mbox_put(cxlds);
return rc;
}
static int cxl_pci_setup_mailbox(struct cxl_dev_state *cxlds)
{
const int cap = readl(cxlds->regs.mbox + CXLDEV_MBOX_CAPS_OFFSET);
cxlds->mbox_send = cxl_pci_mbox_send;
cxlds->payload_size =
1 << FIELD_GET(CXLDEV_MBOX_CAP_PAYLOAD_SIZE_MASK, cap);
/*
* CXL 2.0 8.2.8.4.3 Mailbox Capabilities Register
*
* If the size is too small, mandatory commands will not work and so
* there's no point in going forward. If the size is too large, there's
* no harm is soft limiting it.
*/
cxlds->payload_size = min_t(size_t, cxlds->payload_size, SZ_1M);
if (cxlds->payload_size < 256) {
dev_err(cxlds->dev, "Mailbox is too small (%zub)",
cxlds->payload_size);
return -ENXIO;
}
dev_dbg(cxlds->dev, "Mailbox payload sized %zu",
cxlds->payload_size);
return 0;
}
static int cxl_map_regblock(struct pci_dev *pdev, struct cxl_register_map *map)
{
void __iomem *addr;
int bar = map->barno;
struct device *dev = &pdev->dev;
resource_size_t offset = map->block_offset;
/* Basic sanity check that BAR is big enough */
if (pci_resource_len(pdev, bar) < offset) {
dev_err(dev, "BAR%d: %pr: too small (offset: %pa)\n", bar,
&pdev->resource[bar], &offset);
return -ENXIO;
}
addr = pci_iomap(pdev, bar, 0);
if (!addr) {
dev_err(dev, "failed to map registers\n");
return -ENOMEM;
}
dev_dbg(dev, "Mapped CXL Memory Device resource bar %u @ %pa\n",
bar, &offset);
map->base = addr + map->block_offset;
return 0;
}
static void cxl_unmap_regblock(struct pci_dev *pdev,
struct cxl_register_map *map)
{
pci_iounmap(pdev, map->base - map->block_offset);
map->base = NULL;
}
static int cxl_probe_regs(struct pci_dev *pdev, struct cxl_register_map *map)
{
struct cxl_component_reg_map *comp_map;
struct cxl_device_reg_map *dev_map;
struct device *dev = &pdev->dev;
void __iomem *base = map->base;
switch (map->reg_type) {
case CXL_REGLOC_RBI_COMPONENT:
comp_map = &map->component_map;
cxl_probe_component_regs(dev, base, comp_map);
if (!comp_map->hdm_decoder.valid) {
dev_err(dev, "HDM decoder registers not found\n");
return -ENXIO;
}
dev_dbg(dev, "Set up component registers\n");
break;
case CXL_REGLOC_RBI_MEMDEV:
dev_map = &map->device_map;
cxl_probe_device_regs(dev, base, dev_map);
if (!dev_map->status.valid || !dev_map->mbox.valid ||
!dev_map->memdev.valid) {
dev_err(dev, "registers not found: %s%s%s\n",
!dev_map->status.valid ? "status " : "",
!dev_map->mbox.valid ? "mbox " : "",
!dev_map->memdev.valid ? "memdev " : "");
return -ENXIO;
}
dev_dbg(dev, "Probing device registers...\n");
break;
default:
break;
}
return 0;
}
static int cxl_map_regs(struct cxl_dev_state *cxlds, struct cxl_register_map *map)
{
struct device *dev = cxlds->dev;
struct pci_dev *pdev = to_pci_dev(dev);
switch (map->reg_type) {
case CXL_REGLOC_RBI_COMPONENT:
cxl_map_component_regs(pdev, &cxlds->regs.component, map);
dev_dbg(dev, "Mapping component registers...\n");
break;
case CXL_REGLOC_RBI_MEMDEV:
cxl_map_device_regs(pdev, &cxlds->regs.device_regs, map);
dev_dbg(dev, "Probing device registers...\n");
break;
default:
break;
}
return 0;
}
static void cxl_decode_regblock(u32 reg_lo, u32 reg_hi,
struct cxl_register_map *map)
{
map->block_offset =
((u64)reg_hi << 32) | (reg_lo & CXL_REGLOC_ADDR_MASK);
map->barno = FIELD_GET(CXL_REGLOC_BIR_MASK, reg_lo);
map->reg_type = FIELD_GET(CXL_REGLOC_RBI_MASK, reg_lo);
}
/**
* cxl_find_regblock() - Locate register blocks by type
* @pdev: The CXL PCI device to enumerate.
* @type: Register Block Indicator id
* @map: Enumeration output, clobbered on error
*
* Return: 0 if register block enumerated, negative error code otherwise
*
* A CXL DVSEC may point to one or more register blocks, search for them
* by @type.
*/
static int cxl_find_regblock(struct pci_dev *pdev, enum cxl_regloc_type type,
struct cxl_register_map *map)
{
u32 regloc_size, regblocks;
int regloc, i;
regloc = pci_find_dvsec_capability(pdev, PCI_DVSEC_VENDOR_ID_CXL,
PCI_DVSEC_ID_CXL_REGLOC_DVSEC_ID);
if (!regloc)
return -ENXIO;
pci_read_config_dword(pdev, regloc + PCI_DVSEC_HEADER1, &regloc_size);
regloc_size = FIELD_GET(PCI_DVSEC_HEADER1_LENGTH_MASK, regloc_size);
regloc += PCI_DVSEC_ID_CXL_REGLOC_BLOCK1_OFFSET;
regblocks = (regloc_size - PCI_DVSEC_ID_CXL_REGLOC_BLOCK1_OFFSET) / 8;
for (i = 0; i < regblocks; i++, regloc += 8) {
u32 reg_lo, reg_hi;
pci_read_config_dword(pdev, regloc, &reg_lo);
pci_read_config_dword(pdev, regloc + 4, &reg_hi);
cxl_decode_regblock(reg_lo, reg_hi, map);
if (map->reg_type == type)
return 0;
}
return -ENODEV;
}
static int cxl_setup_regs(struct pci_dev *pdev, enum cxl_regloc_type type,
struct cxl_register_map *map)
{
int rc;
rc = cxl_find_regblock(pdev, type, map);
if (rc)
return rc;
rc = cxl_map_regblock(pdev, map);
if (rc)
return rc;
rc = cxl_probe_regs(pdev, map);
cxl_unmap_regblock(pdev, map);
return rc;
}
static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
struct cxl_register_map map;
struct cxl_memdev *cxlmd;
struct cxl_dev_state *cxlds;
int rc;
/*
* Double check the anonymous union trickery in struct cxl_regs
* FIXME switch to struct_group()
*/
BUILD_BUG_ON(offsetof(struct cxl_regs, memdev) !=
offsetof(struct cxl_regs, device_regs.memdev));
rc = pcim_enable_device(pdev);
if (rc)
return rc;
cxlds = cxl_dev_state_create(&pdev->dev);
if (IS_ERR(cxlds))
return PTR_ERR(cxlds);
rc = cxl_setup_regs(pdev, CXL_REGLOC_RBI_MEMDEV, &map);
if (rc)
return rc;
rc = cxl_map_regs(cxlds, &map);
if (rc)
return rc;
rc = cxl_pci_setup_mailbox(cxlds);
if (rc)
return rc;
rc = cxl_enumerate_cmds(cxlds);
if (rc)
return rc;
rc = cxl_dev_state_identify(cxlds);
if (rc)
return rc;
rc = cxl_mem_create_range_info(cxlds);
if (rc)
return rc;
cxlmd = devm_cxl_add_memdev(cxlds);
if (IS_ERR(cxlmd))
return PTR_ERR(cxlmd);
if (range_len(&cxlds->pmem_range) && IS_ENABLED(CONFIG_CXL_PMEM))
rc = devm_cxl_add_nvdimm(&pdev->dev, cxlmd);
return rc;
}
static const struct pci_device_id cxl_mem_pci_tbl[] = {
/* PCI class code for CXL.mem Type-3 Devices */
{ PCI_DEVICE_CLASS((PCI_CLASS_MEMORY_CXL << 8 | CXL_MEMORY_PROGIF), ~0)},
{ /* terminate list */ },
};
MODULE_DEVICE_TABLE(pci, cxl_mem_pci_tbl);
static struct pci_driver cxl_pci_driver = {
.name = KBUILD_MODNAME,
.id_table = cxl_mem_pci_tbl,
.probe = cxl_pci_probe,
.driver = {
.probe_type = PROBE_PREFER_ASYNCHRONOUS,
},
};
MODULE_LICENSE("GPL v2");
module_pci_driver(cxl_pci_driver);
MODULE_IMPORT_NS(CXL);