drm/xe/xe_mmio.c

// SPDX-License-Identifier: MIT
/*
 * Copyright © 2021-2023 Intel Corporation
 */

#include "xe_mmio.h"

#include <linux/delay.h>
#include <linux/io-64-nonatomic-lo-hi.h>
#include <linux/minmax.h>
#include <linux/pci.h>

#include <drm/drm_managed.h>

#include "regs/xe_bars.h"
#include "xe_device.h"
#include "xe_gt_sriov_vf.h"
#include "xe_printk.h"
#include "xe_sriov.h"
#include "xe_tile_printk.h"
#include "xe_trace.h"
#include "xe_wa.h"

#include "generated/xe_device_wa_oob.h"

/*
 * On multi-tile devices, partition the BAR space for MMIO on each tile,
 * possibly accounting for register override on the number of tiles available.
 * tile_mmio_size contains both the tile's 4MB register space, as well as
 * additional space for the GTT and other (possibly unused) regions).
 * Resulting memory layout is like below:
 *
 * .----------------------. <- tile_count * tile_mmio_size
 * |         ....         |
 * |----------------------| <- 2 * tile_mmio_size
 * |   tile1 GTT + other  |
 * |----------------------| <- 1 * tile_mmio_size + 4MB
 * |   tile1->mmio.regs   |
 * |----------------------| <- 1 * tile_mmio_size
 * |   tile0 GTT + other  |
 * |----------------------| <- 4MB
 * |   tile0->mmio.regs   |
 * '----------------------' <- 0MB
 */
static void mmio_multi_tile_setup(struct xe_device *xe, size_t tile_mmio_size)
{
	struct xe_tile *tile;
	u8 id;

	for_each_remote_tile(tile, xe, id)
		xe_mmio_init(&tile->mmio, tile, xe->mmio.regs + id * tile_mmio_size, SZ_4M);
}

/**
 * xe_mmio_probe_tiles() - Initialize all tiles' MMIO
 * @xe: the &xe_device
 *
 * Initialize the remaining tiles' MMIO instances.
 *
 * Return: 0 on success or a negative error code on failure.
 */
int xe_mmio_probe_tiles(struct xe_device *xe)
{
	size_t tile_mmio_size = SZ_16M;

	/*
	 * Nothing to be done as tile 0 has already been setup earlier with the
	 * entire BAR mapped - see xe_mmio_probe_early()
	 */
	if (xe->info.tile_count == 1)
		return 0;

	if (xe->mmio.size < xe->info.tile_count * tile_mmio_size) {
		xe_err(xe, "GTTMMADR_BAR is too small for %d tiles: %zu\n",
		       xe->info.tile_count, xe->mmio.size);
		return -EIO;
	}

	mmio_multi_tile_setup(xe, tile_mmio_size);
	return 0;
}

static void mmio_fini(void *arg)
{
	struct xe_device *xe = arg;

	xe->mmio.regs = NULL;
}

/**
 * xe_mmio_probe_early() - Probe and initialize device's MMIO
 * @xe: the &xe_device
 *
 * Map the entire GTTMMADR_BAR and initialize the first tile's MMIO instance.
 *
 * The first 16MB of the GTTMMADR_BAR always belongs to the root tile, and
 * includes: registers (0-4MB), reserved space (4MB-8MB) and GGTT (8MB-16MB).
 *
 * Return: 0 on success or a negative error code on failure.
 */
int xe_mmio_probe_early(struct xe_device *xe)
{
	struct xe_tile *root_tile = xe_device_get_root_tile(xe);
	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);

	xe->mmio.regs = pcim_iomap(pdev, GTTMMADR_BAR, 0);
	if (!xe->mmio.regs) {
		xe_err(xe, "Failed to map GTTMMADR_BAR\n");
		return -EIO;
	}

	xe->mmio.size = pci_resource_len(pdev, GTTMMADR_BAR);
	if (xe->mmio.size < SZ_16M) {
		xe_err(xe, "GTTMMADR_BAR is too small: %zu\n", xe->mmio.size);
		return -EIO;
	}

	/* Setup first tile; other tiles (if present) will be setup later. */
	xe_mmio_init(&root_tile->mmio, root_tile, xe->mmio.regs, SZ_4M);

	return devm_add_action_or_reset(xe->drm.dev, mmio_fini, xe);
}
ALLOW_ERROR_INJECTION(xe_mmio_probe_early, ERRNO); /* See xe_pci_probe() */

/**
 * xe_mmio_init() - Initialize an MMIO instance
 * @mmio: Pointer to the MMIO instance to initialize
 * @tile: The tile to which the MMIO region belongs
 * @ptr: Pointer to the start of the MMIO region
 * @size: The size of the MMIO region in bytes
 *
 * This is a convenience function for minimal initialization of struct xe_mmio.
 */
void xe_mmio_init(struct xe_mmio *mmio, struct xe_tile *tile, void __iomem *ptr, u32 size)
{
	xe_tile_assert(tile, size <= XE_REG_ADDR_MAX);

	mmio->regs = ptr;
	mmio->regs_size = size;
	mmio->tile = tile;
}

static bool mmio_available(struct xe_mmio *mmio)
{
	return !xe_tile_WARN_ON_ONCE(mmio->tile, !mmio->tile->xe->mmio.regs);
}

static void mmio_flush_pending_writes(struct xe_mmio *mmio)
{
#define DUMMY_REG_OFFSET	0x130030
	int i;

	if (!XE_DEVICE_WA(mmio->tile->xe, 15015404425))
		return;

	/* 4 dummy writes */
	for (i = 0; i < 4; i++)
		writel(0, mmio->regs + DUMMY_REG_OFFSET);
}

u8 xe_mmio_read8(struct xe_mmio *mmio, struct xe_reg reg)
{
	u32 addr = xe_mmio_adjusted_addr(mmio, reg.addr);
	u8 val;

	if (!mmio_available(mmio))
		return 0;

	mmio_flush_pending_writes(mmio);

	val = readb(mmio->regs + addr);
	trace_xe_reg_rw(mmio, false, addr, val, sizeof(val));

	return val;
}

void xe_mmio_write8(struct xe_mmio *mmio, struct xe_reg reg, u8 val)
{
	u32 addr = xe_mmio_adjusted_addr(mmio, reg.addr);

	if (!mmio_available(mmio))
		return;

	trace_xe_reg_rw(mmio, true, addr, val, sizeof(val));

	writeb(val, mmio->regs + addr);
}

u16 xe_mmio_read16(struct xe_mmio *mmio, struct xe_reg reg)
{
	u32 addr = xe_mmio_adjusted_addr(mmio, reg.addr);
	u16 val;

	if (!mmio_available(mmio))
		return 0;

	mmio_flush_pending_writes(mmio);

	val = readw(mmio->regs + addr);
	trace_xe_reg_rw(mmio, false, addr, val, sizeof(val));

	return val;
}

void xe_mmio_write32(struct xe_mmio *mmio, struct xe_reg reg, u32 val)
{
	u32 addr = xe_mmio_adjusted_addr(mmio, reg.addr);

	if (!mmio_available(mmio))
		return;

	trace_xe_reg_rw(mmio, true, addr, val, sizeof(val));

	if (!reg.vf && IS_SRIOV_VF(mmio->tile->xe))
		xe_gt_sriov_vf_write32(mmio->sriov_vf_gt ?:
				       mmio->tile->primary_gt, reg, val);
	else
		writel(val, mmio->regs + addr);
}

u32 xe_mmio_read32(struct xe_mmio *mmio, struct xe_reg reg)
{
	u32 addr = xe_mmio_adjusted_addr(mmio, reg.addr);
	u32 val;

	if (!mmio_available(mmio))
		return 0;

	mmio_flush_pending_writes(mmio);

	if (!reg.vf && IS_SRIOV_VF(mmio->tile->xe))
		val = xe_gt_sriov_vf_read32(mmio->sriov_vf_gt ?:
					    mmio->tile->primary_gt, reg);
	else
		val = readl(mmio->regs + addr);

	trace_xe_reg_rw(mmio, false, addr, val, sizeof(val));

	return val;
}

u32 xe_mmio_rmw32(struct xe_mmio *mmio, struct xe_reg reg, u32 clr, u32 set)
{
	u32 old, reg_val;

	old = xe_mmio_read32(mmio, reg);
	reg_val = (old & ~clr) | set;
	xe_mmio_write32(mmio, reg, reg_val);

	return old;
}

int xe_mmio_write32_and_verify(struct xe_mmio *mmio,
			       struct xe_reg reg, u32 val, u32 mask, u32 eval)
{
	u32 reg_val;

	xe_mmio_write32(mmio, reg, val);
	reg_val = xe_mmio_read32(mmio, reg);

	return (reg_val & mask) != eval ? -EINVAL : 0;
}

bool xe_mmio_in_range(const struct xe_mmio *mmio,
		      const struct xe_mmio_range *range,
		      struct xe_reg reg)
{
	u32 addr = xe_mmio_adjusted_addr(mmio, reg.addr);

	return range && addr >= range->start && addr <= range->end;
}

/**
 * xe_mmio_read64_2x32() - Read a 64-bit register as two 32-bit reads
 * @mmio: MMIO target
 * @reg: register to read value from
 *
 * Although Intel GPUs have some 64-bit registers, the hardware officially
 * only supports GTTMMADR register reads of 32 bits or smaller.  Even if
 * a readq operation may return a reasonable value, that violation of the
 * spec shouldn't be relied upon and all 64-bit register reads should be
 * performed as two 32-bit reads of the upper and lower dwords.
 *
 * When reading registers that may be changing (such as
 * counters), a rollover of the lower dword between the two 32-bit reads
 * can be problematic.  This function attempts to ensure the upper dword has
 * stabilized before returning the 64-bit value.
 *
 * Note that because this function may re-read the register multiple times
 * while waiting for the value to stabilize it should not be used to read
 * any registers where read operations have side effects.
 *
 * Returns the value of the 64-bit register.
 */
u64 xe_mmio_read64_2x32(struct xe_mmio *mmio, struct xe_reg reg)
{
	struct xe_reg reg_udw = { .addr = reg.addr + 0x4 };
	u32 ldw, udw, oldudw, retries;

	/*
	 * The two dwords of a 64-bit register can never straddle the offset
	 * adjustment cutoff.
	 */
	xe_tile_assert(mmio->tile, !in_range(mmio->adj_limit, reg.addr + 1, 7));

	oldudw = xe_mmio_read32(mmio, reg_udw);
	for (retries = 5; retries; --retries) {
		ldw = xe_mmio_read32(mmio, reg);
		udw = xe_mmio_read32(mmio, reg_udw);

		if (udw == oldudw)
			break;

		oldudw = udw;
	}

	xe_tile_WARN(mmio->tile, retries == 0,
		     "MMIO: 64-bit read of %#x did not stabilize\n", reg.addr);

	return (u64)udw << 32 | ldw;
}

#define __XE_MMIO_WAIT_MAX_BACKOFF_100MS (100 * USEC_PER_MSEC)
static int __xe_mmio_wait32(struct xe_mmio *mmio, struct xe_reg reg, u32 mask, u32 val,
			    u32 timeout_us, u32 *out_val, bool atomic, bool expect_match)
{
	ktime_t cur = ktime_get_raw();
	const ktime_t end = ktime_add_us(cur, timeout_us);
	int ret = -ETIMEDOUT;
	s64 wait = 10;
	u32 read;
	bool check;

	for (;;) {
		read = xe_mmio_read32(mmio, reg);

		check = (read & mask) == val;
		if (!expect_match)
			check = !check;

		if (check) {
			ret = 0;
			break;
		}

		cur = ktime_get_raw();
		if (!ktime_before(cur, end))
			break;

		if (ktime_after(ktime_add_us(cur, wait), end))
			wait = ktime_us_delta(end, cur);

		if (atomic)
			udelay(min_t(s64, wait, (MAX_UDELAY_MS * 1000)));
		else
			usleep_range(wait, wait << 1);
		wait = min_t(s64, wait << 1, __XE_MMIO_WAIT_MAX_BACKOFF_100MS);
	}

	if (ret != 0) {
		read = xe_mmio_read32(mmio, reg);

		check = (read & mask) == val;
		if (!expect_match)
			check = !check;

		if (check)
			ret = 0;
	}

	if (out_val)
		*out_val = read;

	return ret;
}

/**
 * xe_mmio_wait32() - Wait for a register to match the desired masked value
 * @mmio: MMIO target
 * @reg: register to read value from
 * @mask: mask to be applied to the value read from the register
 * @val: desired value after applying the mask
 * @timeout_us: time out after this period of time. Wait logic tries to be
 * smart, applying an exponential backoff until @timeout_us is reached.
 * @out_val: if not NULL, points where to store the last unmasked value
 * @atomic: needs to be true if calling from an atomic context
 *
 * This function polls for the desired masked value and returns zero on success
 * or -ETIMEDOUT if timed out.
 *
 * Note that @timeout_us represents the minimum amount of time to wait before
 * giving up. The actual time taken by this function can be a little more than
 * @timeout_us for different reasons, specially in non-atomic contexts. Thus,
 * it is possible that this function succeeds even after @timeout_us has passed.
 */
int xe_mmio_wait32(struct xe_mmio *mmio, struct xe_reg reg, u32 mask, u32 val, u32 timeout_us,
		   u32 *out_val, bool atomic)
{
	return __xe_mmio_wait32(mmio, reg, mask, val, timeout_us, out_val, atomic, true);
}

/**
 * xe_mmio_wait32_not() - Wait for a register to return anything other than the given masked value
 * @mmio: MMIO target
 * @reg: register to read value from
 * @mask: mask to be applied to the value read from the register
 * @val: value not to be matched after applying the mask
 * @timeout_us: time out after this period of time
 * @out_val: if not NULL, points where to store the last unmasked value
 * @atomic: needs to be true if calling from an atomic context
 *
 * This function works exactly like xe_mmio_wait32() with the exception that
 * @val is expected not to be matched.
 */
int xe_mmio_wait32_not(struct xe_mmio *mmio, struct xe_reg reg, u32 mask, u32 val, u32 timeout_us,
		       u32 *out_val, bool atomic)
{
	return __xe_mmio_wait32(mmio, reg, mask, val, timeout_us, out_val, atomic, false);
}

#ifdef CONFIG_PCI_IOV
static size_t vf_regs_stride(struct xe_device *xe)
{
	return GRAPHICS_VERx100(xe) > 1200 ? 0x400 : 0x1000;
}

/**
 * xe_mmio_init_vf_view() - Initialize an MMIO instance for accesses like the VF
 * @mmio: the target &xe_mmio to initialize as VF's view
 * @base: the source &xe_mmio to initialize from
 * @vfid: the VF identifier
 */
void xe_mmio_init_vf_view(struct xe_mmio *mmio, const struct xe_mmio *base, unsigned int vfid)
{
	struct xe_tile *tile = base->tile;
	struct xe_device *xe = tile->xe;
	size_t offset = vf_regs_stride(xe) * vfid;

	xe_assert(xe, IS_SRIOV_PF(xe));
	xe_assert(xe, vfid);
	xe_assert(xe, !base->sriov_vf_gt);
	xe_assert(xe, base->regs_size > offset);

	*mmio = *base;
	mmio->regs += offset;
	mmio->regs_size -= offset;
}
#endif