[PATCH v7 06/16] intel-ipu3: mmu: Implement driver

[Yong Zhi <yong.zhi@intel.com>]

From: Tomasz Figa <tfiga@chromium.org>

This driver translates IO virtual address to physical
address based on two levels page tables.

Signed-off-by: Tomasz Figa <tfiga@chromium.org>
Signed-off-by: Yong Zhi <yong.zhi@intel.com>
---
 drivers/media/pci/intel/ipu3/ipu3-mmu.c | 560 ++++++++++++++++++++++++++++++++
 drivers/media/pci/intel/ipu3/ipu3-mmu.h |  35 ++
 2 files changed, 595 insertions(+)
 create mode 100644 drivers/media/pci/intel/ipu3/ipu3-mmu.c
 create mode 100644 drivers/media/pci/intel/ipu3/ipu3-mmu.h

diff --git a/drivers/media/pci/intel/ipu3/ipu3-mmu.c b/drivers/media/pci/intel/ipu3/ipu3-mmu.c
new file mode 100644
index 0000000..b66734a
--- /dev/null
+++ b/drivers/media/pci/intel/ipu3/ipu3-mmu.c
@@ -0,0 +1,560 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 Intel Corporation.
+ * Copyright 2018 Google LLC.
+ *
+ * Author: Tuukka Toivonen <tuukka.toivonen@intel.com>
+ * Author: Sakari Ailus <sakari.ailus@linux.intel.com>
+ * Author: Samu Onkalo <samu.onkalo@intel.com>
+ * Author: Tomasz Figa <tfiga@chromium.org>
+ *
+ */
+
+#include <linux/dma-mapping.h>
+#include <linux/iopoll.h>
+#include <linux/pm_runtime.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+
+#include <asm/set_memory.h>
+
+#include "ipu3-mmu.h"
+
+#define IPU3_PAGE_SHIFT		12
+#define IPU3_PAGE_SIZE		(1UL << IPU3_PAGE_SHIFT)
+
+#define IPU3_PT_BITS		10
+#define IPU3_PT_PTES		(1UL << IPU3_PT_BITS)
+#define IPU3_PT_SIZE		(IPU3_PT_PTES << 2)
+#define IPU3_PT_ORDER		(IPU3_PT_SIZE >> PAGE_SHIFT)
+
+#define IPU3_ADDR2PTE(addr)	((addr) >> IPU3_PAGE_SHIFT)
+#define IPU3_PTE2ADDR(pte)	((phys_addr_t)(pte) << IPU3_PAGE_SHIFT)
+
+#define IPU3_L2PT_SHIFT		IPU3_PT_BITS
+#define IPU3_L2PT_MASK		((1UL << IPU3_L2PT_SHIFT) - 1)
+
+#define IPU3_L1PT_SHIFT		IPU3_PT_BITS
+#define IPU3_L1PT_MASK		((1UL << IPU3_L1PT_SHIFT) - 1)
+
+#define IPU3_MMU_ADDRESS_BITS	(IPU3_PAGE_SHIFT + \
+				 IPU3_L2PT_SHIFT + \
+				 IPU3_L1PT_SHIFT)
+
+#define IMGU_REG_BASE		0x4000
+#define REG_TLB_INVALIDATE	(IMGU_REG_BASE + 0x300)
+#define TLB_INVALIDATE		1
+#define REG_L1_PHYS		(IMGU_REG_BASE + 0x304) /* 27-bit pfn */
+#define REG_GP_HALT		(IMGU_REG_BASE + 0x5dc)
+#define REG_GP_HALTED		(IMGU_REG_BASE + 0x5e0)
+
+struct ipu3_mmu {
+	struct device *dev;
+	void __iomem *base;
+	/* protect access to l2pts, l1pt */
+	spinlock_t lock;
+
+	void *dummy_page;
+	u32 dummy_page_pteval;
+
+	u32 *dummy_l2pt;
+	u32 dummy_l2pt_pteval;
+
+	u32 **l2pts;
+	u32 *l1pt;
+
+	struct ipu3_mmu_info geometry;
+};
+
+static inline struct ipu3_mmu *to_ipu3_mmu(struct ipu3_mmu_info *info)
+{
+	return container_of(info, struct ipu3_mmu, geometry);
+}
+
+/**
+ * ipu3_mmu_tlb_invalidate - invalidate translation look-aside buffer
+ * @mmu: MMU to perform the invalidate operation on
+ *
+ * This function invalidates the whole TLB. Must be called when the hardware
+ * is powered on.
+ */
+static void ipu3_mmu_tlb_invalidate(struct ipu3_mmu *mmu)
+{
+	writel(TLB_INVALIDATE, mmu->base + REG_TLB_INVALIDATE);
+}
+
+static void call_if_ipu3_is_powered(struct ipu3_mmu *mmu,
+				    void (*func)(struct ipu3_mmu *mmu))
+{
+	pm_runtime_get_noresume(mmu->dev);
+	if (pm_runtime_active(mmu->dev))
+		func(mmu);
+	pm_runtime_put(mmu->dev);
+}
+
+/**
+ * ipu3_mmu_set_halt - set CIO gate halt bit
+ * @mmu: MMU to set the CIO gate bit in.
+ * @halt: Desired state of the gate bit.
+ *
+ * This function sets the CIO gate bit that controls whether external memory
+ * accesses are allowed. Must be called when the hardware is powered on.
+ */
+static void ipu3_mmu_set_halt(struct ipu3_mmu *mmu, bool halt)
+{
+	int ret;
+	u32 val;
+
+	writel(halt, mmu->base + REG_GP_HALT);
+	ret = readl_poll_timeout(mmu->base + REG_GP_HALTED,
+				 val, (val & 1) == halt, 1000, 100000);
+
+	if (ret)
+		dev_err(mmu->dev, "failed to %s CIO gate halt\n",
+			halt ? "set" : "clear");
+}
+
+/**
+ * ipu3_mmu_alloc_page_table - allocate a pre-filled page table
+ * @pteval: Value to initialize for page table entries with.
+ *
+ * Return: Pointer to allocated page table or NULL on failure.
+ */
+static u32 *ipu3_mmu_alloc_page_table(u32 pteval)
+{
+	u32 *pt;
+	int pte;
+
+	pt = (u32 *)__get_free_page(GFP_KERNEL);
+	if (!pt)
+		return NULL;
+
+	for (pte = 0; pte < IPU3_PT_PTES; pte++)
+		pt[pte] = pteval;
+
+	set_memory_uc((unsigned long int)pt, IPU3_PT_ORDER);
+
+	return pt;
+}
+
+/**
+ * ipu3_mmu_free_page_table - free page table
+ * @pt: Page table to free.
+ */
+static void ipu3_mmu_free_page_table(u32 *pt)
+{
+	set_memory_wb((unsigned long int)pt, IPU3_PT_ORDER);
+	free_page((unsigned long)pt);
+}
+
+/**
+ * address_to_pte_idx - split IOVA into L1 and L2 page table indices
+ * @iova: IOVA to split.
+ * @l1pt_idx: Output for the L1 page table index.
+ * @l2pt_idx: Output for the L2 page index.
+ */
+static inline void address_to_pte_idx(unsigned long iova, u32 *l1pt_idx,
+				      u32 *l2pt_idx)
+{
+	iova >>= IPU3_PAGE_SHIFT;
+
+	if (l2pt_idx)
+		*l2pt_idx = iova & IPU3_L2PT_MASK;
+
+	iova >>= IPU3_L2PT_SHIFT;
+
+	if (l1pt_idx)
+		*l1pt_idx = iova & IPU3_L1PT_MASK;
+}
+
+static u32 *ipu3_mmu_get_l2pt(struct ipu3_mmu *mmu, u32 l1pt_idx)
+{
+	unsigned long flags;
+	u32 *l2pt, *new_l2pt;
+	u32 pteval;
+
+	spin_lock_irqsave(&mmu->lock, flags);
+
+	l2pt = mmu->l2pts[l1pt_idx];
+	if (l2pt)
+		goto done;
+
+	spin_unlock_irqrestore(&mmu->lock, flags);
+
+	new_l2pt = ipu3_mmu_alloc_page_table(mmu->dummy_page_pteval);
+	if (!new_l2pt)
+		return NULL;
+
+	spin_lock_irqsave(&mmu->lock, flags);
+
+	dev_dbg(mmu->dev, "allocated page table %p for l1pt_idx %u\n",
+		new_l2pt, l1pt_idx);
+
+	l2pt = mmu->l2pts[l1pt_idx];
+	if (l2pt) {
+		ipu3_mmu_free_page_table(new_l2pt);
+		goto done;
+	}
+
+	l2pt = new_l2pt;
+	mmu->l2pts[l1pt_idx] = new_l2pt;
+
+	pteval = IPU3_ADDR2PTE(virt_to_phys(new_l2pt));
+	mmu->l1pt[l1pt_idx] = pteval;
+
+done:
+	spin_unlock_irqrestore(&mmu->lock, flags);
+	return l2pt;
+}
+
+static int __ipu3_mmu_map(struct ipu3_mmu *mmu, unsigned long iova,
+			  phys_addr_t paddr)
+{
+	u32 l1pt_idx, l2pt_idx;
+	unsigned long flags;
+	u32 *l2pt;
+
+	if (!mmu)
+		return -ENODEV;
+
+	address_to_pte_idx(iova, &l1pt_idx, &l2pt_idx);
+
+	l2pt = ipu3_mmu_get_l2pt(mmu, l1pt_idx);
+	if (!l2pt)
+		return -ENOMEM;
+
+	spin_lock_irqsave(&mmu->lock, flags);
+
+	if (l2pt[l2pt_idx] != mmu->dummy_page_pteval) {
+		spin_unlock_irqrestore(&mmu->lock, flags);
+		return -EBUSY;
+	}
+
+	l2pt[l2pt_idx] = IPU3_ADDR2PTE(paddr);
+
+	spin_unlock_irqrestore(&mmu->lock, flags);
+
+	return 0;
+}
+
+/**
+ * The following four functions are implemented based on iommu.c
+ * drivers/iommu/iommu.c/iommu_pgsize().
+ */
+static size_t ipu3_mmu_pgsize(unsigned long pgsize_bitmap,
+			      unsigned long addr_merge, size_t size)
+{
+	unsigned int pgsize_idx;
+	size_t pgsize;
+
+	/* Max page size that still fits into 'size' */
+	pgsize_idx = __fls(size);
+
+	/* need to consider alignment requirements ? */
+	if (likely(addr_merge)) {
+		/* Max page size allowed by address */
+		unsigned int align_pgsize_idx = __ffs(addr_merge);
+
+		pgsize_idx = min(pgsize_idx, align_pgsize_idx);
+	}
+
+	/* build a mask of acceptable page sizes */
+	pgsize = (1UL << (pgsize_idx + 1)) - 1;
+
+	/* throw away page sizes not supported by the hardware */
+	pgsize &= pgsize_bitmap;
+
+	/* make sure we're still sane */
+	WARN_ON(!pgsize);
+
+	/* pick the biggest page */
+	pgsize_idx = __fls(pgsize);
+	pgsize = 1UL << pgsize_idx;
+
+	return pgsize;
+}
+
+/* drivers/iommu/iommu.c/iommu_map() */
+int ipu3_mmu_map(struct ipu3_mmu_info *info, unsigned long iova,
+		 phys_addr_t paddr, size_t size)
+{
+	struct ipu3_mmu *mmu = to_ipu3_mmu(info);
+	unsigned int min_pagesz;
+	int ret = 0;
+
+	/* find out the minimum page size supported */
+	min_pagesz = 1 << __ffs(mmu->geometry.pgsize_bitmap);
+
+	/*
+	 * both the virtual address and the physical one, as well as
+	 * the size of the mapping, must be aligned (at least) to the
+	 * size of the smallest page supported by the hardware
+	 */
+	if (!IS_ALIGNED(iova | paddr | size, min_pagesz)) {
+		dev_err(mmu->dev, "unaligned: iova 0x%lx pa %pa size 0x%zx min_pagesz 0x%x\n",
+			iova, &paddr, size, min_pagesz);
+		return -EINVAL;
+	}
+
+	dev_dbg(mmu->dev, "map: iova 0x%lx pa %pa size 0x%zx\n",
+		iova, &paddr, size);
+
+	while (size) {
+		size_t pgsize = ipu3_mmu_pgsize(mmu->geometry.pgsize_bitmap,
+						iova | paddr, size);
+
+		dev_dbg(mmu->dev, "mapping: iova 0x%lx pa %pa pgsize 0x%zx\n",
+			iova, &paddr, pgsize);
+
+		ret = __ipu3_mmu_map(mmu, iova, paddr);
+		if (ret)
+			break;
+
+		iova += pgsize;
+		paddr += pgsize;
+		size -= pgsize;
+	}
+
+	call_if_ipu3_is_powered(mmu, ipu3_mmu_tlb_invalidate);
+
+	return ret;
+}
+
+/* drivers/iommu/iommu.c/default_iommu_map_sg() */
+size_t ipu3_mmu_map_sg(struct ipu3_mmu_info *info, unsigned long iova,
+		       struct scatterlist *sg, unsigned int nents)
+{
+	struct ipu3_mmu *mmu = to_ipu3_mmu(info);
+	struct scatterlist *s;
+	size_t s_length, mapped = 0;
+	unsigned int i, min_pagesz;
+	int ret;
+
+	min_pagesz = 1 << __ffs(mmu->geometry.pgsize_bitmap);
+
+	for_each_sg(sg, s, nents, i) {
+		phys_addr_t phys = page_to_phys(sg_page(s)) + s->offset;
+
+		s_length = s->length;
+
+		if (!IS_ALIGNED(s->offset, min_pagesz))
+			goto out_err;
+
+		/* must be min_pagesz aligned to be mapped singlely */
+		if (i == nents - 1 && !IS_ALIGNED(s->length, min_pagesz))
+			s_length = PAGE_ALIGN(s->length);
+
+		ret = ipu3_mmu_map(info, iova + mapped, phys, s_length);
+		if (ret)
+			goto out_err;
+
+		mapped += s_length;
+	}
+
+	call_if_ipu3_is_powered(mmu, ipu3_mmu_tlb_invalidate);
+
+	return mapped;
+
+out_err:
+	/* undo mappings already done */
+	ipu3_mmu_unmap(info, iova, mapped);
+
+	return 0;
+}
+
+static size_t __ipu3_mmu_unmap(struct ipu3_mmu *mmu,
+			       unsigned long iova, size_t size)
+{
+	u32 l1pt_idx, l2pt_idx;
+	unsigned long flags;
+	size_t unmap = size;
+	u32 *l2pt;
+
+	if (!mmu)
+		return 0;
+
+	address_to_pte_idx(iova, &l1pt_idx, &l2pt_idx);
+
+	spin_lock_irqsave(&mmu->lock, flags);
+
+	l2pt = mmu->l2pts[l1pt_idx];
+	if (!l2pt) {
+		spin_unlock_irqrestore(&mmu->lock, flags);
+		return 0;
+	}
+
+	if (l2pt[l2pt_idx] == mmu->dummy_page_pteval)
+		unmap = 0;
+
+	l2pt[l2pt_idx] = mmu->dummy_page_pteval;
+
+	spin_unlock_irqrestore(&mmu->lock, flags);
+
+	return unmap;
+}
+
+/* drivers/iommu/iommu.c/iommu_unmap() */
+size_t ipu3_mmu_unmap(struct ipu3_mmu_info *info, unsigned long iova,
+		      size_t size)
+{
+	struct ipu3_mmu *mmu = to_ipu3_mmu(info);
+	size_t unmapped_page, unmapped = 0;
+	unsigned int min_pagesz;
+
+	/* find out the minimum page size supported */
+	min_pagesz = 1 << __ffs(mmu->geometry.pgsize_bitmap);
+
+	/*
+	 * The virtual address, as well as the size of the mapping, must be
+	 * aligned (at least) to the size of the smallest page supported
+	 * by the hardware
+	 */
+	if (!IS_ALIGNED(iova | size, min_pagesz)) {
+		dev_err(mmu->dev, "unaligned: iova 0x%lx size 0x%zx min_pagesz 0x%x\n",
+			iova, size, min_pagesz);
+		return -EINVAL;
+	}
+
+	dev_dbg(mmu->dev, "unmap this: iova 0x%lx size 0x%zx\n", iova, size);
+
+	/*
+	 * Keep iterating until we either unmap 'size' bytes (or more)
+	 * or we hit an area that isn't mapped.
+	 */
+	while (unmapped < size) {
+		size_t pgsize = ipu3_mmu_pgsize(mmu->geometry.pgsize_bitmap,
+						iova, size - unmapped);
+
+		unmapped_page = __ipu3_mmu_unmap(mmu, iova, pgsize);
+		if (!unmapped_page)
+			break;
+
+		dev_dbg(mmu->dev, "unmapped: iova 0x%lx size 0x%zx\n",
+			iova, unmapped_page);
+
+		iova += unmapped_page;
+		unmapped += unmapped_page;
+	}
+
+	call_if_ipu3_is_powered(mmu, ipu3_mmu_tlb_invalidate);
+
+	return unmapped;
+}
+
+/**
+ * ipu3_mmu_init() - initialize IPU3 MMU block
+ * @base:	IOMEM base of hardware registers.
+ *
+ * Return: Pointer to IPU3 MMU private data pointer or ERR_PTR() on error.
+ */
+struct ipu3_mmu_info *ipu3_mmu_init(struct device *parent, void __iomem *base)
+{
+	struct ipu3_mmu *mmu;
+	u32 pteval;
+
+	mmu = kzalloc(sizeof(*mmu), GFP_KERNEL);
+	if (!mmu)
+		return ERR_PTR(-ENOMEM);
+
+	mmu->dev = parent;
+	mmu->base = base;
+	spin_lock_init(&mmu->lock);
+
+	/* Disallow external memory access when having no valid page tables. */
+	ipu3_mmu_set_halt(mmu, true);
+
+	/*
+	 * The MMU does not have a "valid" bit, so we have to use a dummy
+	 * page for invalid entries.
+	 */
+	mmu->dummy_page = (void *)__get_free_page(GFP_KERNEL);
+	if (!mmu->dummy_page)
+		goto fail_group;
+	pteval = IPU3_ADDR2PTE(virt_to_phys(mmu->dummy_page));
+	mmu->dummy_page_pteval = pteval;
+
+	/*
+	 * Allocate a dummy L2 page table with all entries pointing to
+	 * the dummy page.
+	 */
+	mmu->dummy_l2pt = ipu3_mmu_alloc_page_table(pteval);
+	if (!mmu->dummy_l2pt)
+		goto fail_dummy_page;
+	pteval = IPU3_ADDR2PTE(virt_to_phys(mmu->dummy_l2pt));
+	mmu->dummy_l2pt_pteval = pteval;
+
+	/*
+	 * Allocate the array of L2PT CPU pointers, initialized to zero,
+	 * which means the dummy L2PT allocated above.
+	 */
+	mmu->l2pts = vzalloc(IPU3_PT_PTES * sizeof(*mmu->l2pts));
+	if (!mmu->l2pts)
+		goto fail_l2pt;
+
+	/* Allocate the L1 page table. */
+	mmu->l1pt = ipu3_mmu_alloc_page_table(mmu->dummy_l2pt_pteval);
+	if (!mmu->l1pt)
+		goto fail_l2pts;
+
+	pteval = IPU3_ADDR2PTE(virt_to_phys(mmu->l1pt));
+	writel(pteval, mmu->base + REG_L1_PHYS);
+	ipu3_mmu_tlb_invalidate(mmu);
+	ipu3_mmu_set_halt(mmu, false);
+
+	mmu->geometry.aperture_start = 0;
+	mmu->geometry.aperture_end = DMA_BIT_MASK(IPU3_MMU_ADDRESS_BITS);
+	mmu->geometry.pgsize_bitmap = IPU3_PAGE_SIZE;
+
+	return &mmu->geometry;
+
+fail_l2pts:
+	vfree(mmu->l2pts);
+fail_l2pt:
+	ipu3_mmu_free_page_table(mmu->dummy_l2pt);
+fail_dummy_page:
+	free_page((unsigned long)mmu->dummy_page);
+fail_group:
+	kfree(mmu);
+
+	return ERR_PTR(-ENOMEM);
+}
+
+/**
+ * ipu3_mmu_exit() - clean up IPU3 MMU block
+ * @mmu: IPU3 MMU private data
+ */
+void ipu3_mmu_exit(struct ipu3_mmu_info *info)
+{
+	struct ipu3_mmu *mmu = to_ipu3_mmu(info);
+
+	/* We are going to free our page tables, no more memory access. */
+	ipu3_mmu_set_halt(mmu, true);
+	ipu3_mmu_tlb_invalidate(mmu);
+
+	ipu3_mmu_free_page_table(mmu->l1pt);
+	vfree(mmu->l2pts);
+	ipu3_mmu_free_page_table(mmu->dummy_l2pt);
+	free_page((unsigned long)mmu->dummy_page);
+	kfree(mmu);
+}
+
+void ipu3_mmu_suspend(struct ipu3_mmu_info *info)
+{
+	struct ipu3_mmu *mmu = to_ipu3_mmu(info);
+
+	ipu3_mmu_set_halt(mmu, true);
+}
+
+void ipu3_mmu_resume(struct ipu3_mmu_info *info)
+{
+	struct ipu3_mmu *mmu = to_ipu3_mmu(info);
+	u32 pteval;
+
+	ipu3_mmu_set_halt(mmu, true);
+
+	pteval = IPU3_ADDR2PTE(virt_to_phys(mmu->l1pt));
+	writel(pteval, mmu->base + REG_L1_PHYS);
+
+	ipu3_mmu_tlb_invalidate(mmu);
+	ipu3_mmu_set_halt(mmu, false);
+}
diff --git a/drivers/media/pci/intel/ipu3/ipu3-mmu.h b/drivers/media/pci/intel/ipu3/ipu3-mmu.h
new file mode 100644
index 0000000..8fe63b4
--- /dev/null
+++ b/drivers/media/pci/intel/ipu3/ipu3-mmu.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2018 Intel Corporation */
+/* Copyright 2018 Google LLC. */
+
+#ifndef __IPU3_MMU_H
+#define __IPU3_MMU_H
+
+/**
+ * struct ipu3_mmu_info - Describes mmu geometry
+ *
+ * @aperture_start:	First address that can be mapped
+ * @aperture_end:	Last address that can be mapped
+ * @pgsize_bitmap:	Bitmap of page sizes in use
+ */
+struct ipu3_mmu_info {
+	dma_addr_t aperture_start;
+	dma_addr_t aperture_end;
+	unsigned long pgsize_bitmap;
+};
+
+struct device;
+struct scatterlist;
+
+struct ipu3_mmu_info *ipu3_mmu_init(struct device *parent, void __iomem *base);
+void ipu3_mmu_exit(struct ipu3_mmu_info *info);
+void ipu3_mmu_suspend(struct ipu3_mmu_info *info);
+void ipu3_mmu_resume(struct ipu3_mmu_info *info);
+
+int ipu3_mmu_map(struct ipu3_mmu_info *info, unsigned long iova,
+		 phys_addr_t paddr, size_t size);
+size_t ipu3_mmu_unmap(struct ipu3_mmu_info *info, unsigned long iova,
+		      size_t size);
+size_t ipu3_mmu_map_sg(struct ipu3_mmu_info *info, unsigned long iova,
+		       struct scatterlist *sg, unsigned int nents);
+#endif
-- 
2.7.4