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Subject[PATCH V2] LoongArch: Use TLB for ioremap()
Date
We can support more cache attributes (e.g., CC, SUC and WUC) and page
protection when we use TLB for ioremap(). The implementation is based
on GENERIC_IOREMAP.

The existing simple ioremap() implementation has better performance so
we keep it and introduce ARCH_IOREMAP to control the selection.

We move pagetable_init() earlier to make early ioremap() works, and we
modify the PCI ecam mapping because the TLB-based version of ioremap()
will actually take the size into account.

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
---
V2: Based on GENERIC_IOREMAP.

arch/loongarch/Kconfig | 7 +++
arch/loongarch/include/asm/fixmap.h | 15 +++++
arch/loongarch/include/asm/io.h | 69 ++++++--------------
arch/loongarch/include/asm/pgtable-bits.h | 3 +
arch/loongarch/kernel/setup.c | 2 +-
arch/loongarch/mm/init.c | 64 +++++++++++++++++++
arch/loongarch/pci/acpi.c | 76 +++++++++++++++++++++--
7 files changed, 180 insertions(+), 56 deletions(-)

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 3594f0ba7581..5b89386d6972 100644
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -61,6 +61,7 @@ config LOONGARCH
select GENERIC_CPU_AUTOPROBE
select GENERIC_ENTRY
select GENERIC_GETTIMEOFDAY
+ select GENERIC_IOREMAP if !ARCH_IOREMAP
select GENERIC_IRQ_MULTI_HANDLER
select GENERIC_IRQ_PROBE
select GENERIC_IRQ_SHOW
@@ -168,6 +169,9 @@ config MACH_LOONGSON32
config MACH_LOONGSON64
def_bool 64BIT

+config FIX_EARLYCON_MEM
+ def_bool y
+
config PAGE_SIZE_4KB
bool

@@ -421,6 +425,9 @@ config SECCOMP

endmenu

+config ARCH_IOREMAP
+ bool
+
config ARCH_SELECT_MEMORY_MODEL
def_bool y

diff --git a/arch/loongarch/include/asm/fixmap.h b/arch/loongarch/include/asm/fixmap.h
index b3541dfa2013..d2e55ae55bb9 100644
--- a/arch/loongarch/include/asm/fixmap.h
+++ b/arch/loongarch/include/asm/fixmap.h
@@ -10,4 +10,19 @@

#define NR_FIX_BTMAPS 64

+enum fixed_addresses {
+ FIX_HOLE,
+ FIX_EARLYCON_MEM_BASE,
+ __end_of_fixed_addresses
+};
+
+#define FIXADDR_SIZE (__end_of_fixed_addresses << PAGE_SHIFT)
+#define FIXADDR_START (FIXADDR_TOP - FIXADDR_SIZE)
+#define FIXMAP_PAGE_IO PAGE_KERNEL_SUC
+
+extern void __set_fixmap(enum fixed_addresses idx,
+ phys_addr_t phys, pgprot_t flags);
+
+#include <asm-generic/fixmap.h>
+
#endif
diff --git a/arch/loongarch/include/asm/io.h b/arch/loongarch/include/asm/io.h
index 999944ea1cea..87a88eb792c1 100644
--- a/arch/loongarch/include/asm/io.h
+++ b/arch/loongarch/include/asm/io.h
@@ -27,71 +27,38 @@ extern void __init early_iounmap(void __iomem *addr, unsigned long size);
#define early_memremap early_ioremap
#define early_memunmap early_iounmap

+#ifdef CONFIG_ARCH_IOREMAP
+
static inline void __iomem *ioremap_prot(phys_addr_t offset, unsigned long size,
unsigned long prot_val)
{
- if (prot_val == _CACHE_CC)
+ if (prot_val & _CACHE_CC)
return (void __iomem *)(unsigned long)(CACHE_BASE + offset);
else
return (void __iomem *)(unsigned long)(UNCACHE_BASE + offset);
}

-/*
- * ioremap - map bus memory into CPU space
- * @offset: bus address of the memory
- * @size: size of the resource to map
- *
- * ioremap performs a platform specific sequence of operations to
- * make bus memory CPU accessible via the readb/readw/readl/writeb/
- * writew/writel functions and the other mmio helpers. The returned
- * address is not guaranteed to be usable directly as a virtual
- * address.
- */
-#define ioremap(offset, size) \
- ioremap_prot((offset), (size), _CACHE_SUC)
+#define ioremap(offset, size) \
+ ioremap_prot((offset), (size), pgprot_val(PAGE_KERNEL_SUC))

-/*
- * ioremap_wc - map bus memory into CPU space
- * @offset: bus address of the memory
- * @size: size of the resource to map
- *
- * ioremap_wc performs a platform specific sequence of operations to
- * make bus memory CPU accessible via the readb/readw/readl/writeb/
- * writew/writel functions and the other mmio helpers. The returned
- * address is not guaranteed to be usable directly as a virtual
- * address.
- *
- * This version of ioremap ensures that the memory is marked uncachable
- * but accelerated by means of write-combining feature. It is specifically
- * useful for PCIe prefetchable windows, which may vastly improve a
- * communications performance. If it was determined on boot stage, what
- * CPU CCA doesn't support WUC, the method shall fall-back to the
- * _CACHE_SUC option (see cpu_probe() method).
- */
-#define ioremap_wc(offset, size) \
- ioremap_prot((offset), (size), _CACHE_WUC)
+#define iounmap(addr) do { } while (0)
+
+#endif

/*
- * ioremap_cache - map bus memory into CPU space
- * @offset: bus address of the memory
- * @size: size of the resource to map
- *
- * ioremap_cache performs a platform specific sequence of operations to
- * make bus memory CPU accessible via the readb/readw/readl/writeb/
- * writew/writel functions and the other mmio helpers. The returned
- * address is not guaranteed to be usable directly as a virtual
- * address.
+ * On LoongArch, ioremap() has two variants, ioremap_wc() and ioremap_cache().
+ * They map bus memory into CPU space, the mapped memory is marked uncachable
+ * (_CACHE_SUC), uncachable but accelerated by write-combine (_CACHE_WUC) and
+ * cachable (_CACHE_CC) respectively for CPU access.
*
- * This version of ioremap ensures that the memory is marked cachable by
- * the CPU. Also enables full write-combining. Useful for some
- * memory-like regions on I/O busses.
+ * @offset: bus address of the memory
+ * @size: size of the resource to map
*/
-#define ioremap_cache(offset, size) \
- ioremap_prot((offset), (size), _CACHE_CC)
+#define ioremap_wc(offset, size) \
+ ioremap_prot((offset), (size), pgprot_val(PAGE_KERNEL_WUC))

-static inline void iounmap(const volatile void __iomem *addr)
-{
-}
+#define ioremap_cache(offset, size) \
+ ioremap_prot((offset), (size), pgprot_val(PAGE_KERNEL))

#define mmiowb() asm volatile ("dbar 0" ::: "memory")

diff --git a/arch/loongarch/include/asm/pgtable-bits.h b/arch/loongarch/include/asm/pgtable-bits.h
index 9ca147a29bab..3d1e0a69975a 100644
--- a/arch/loongarch/include/asm/pgtable-bits.h
+++ b/arch/loongarch/include/asm/pgtable-bits.h
@@ -83,8 +83,11 @@
_PAGE_GLOBAL | _PAGE_KERN | _CACHE_SUC)
#define PAGE_KERNEL_WUC __pgprot(_PAGE_PRESENT | __READABLE | __WRITEABLE | \
_PAGE_GLOBAL | _PAGE_KERN | _CACHE_WUC)
+
#ifndef __ASSEMBLY__

+#define _PAGE_IOREMAP pgprot_val(PAGE_KERNEL_SUC)
+
#define pgprot_noncached pgprot_noncached

static inline pgprot_t pgprot_noncached(pgprot_t _prot)
diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
index 2b4e98170bc1..f938aae3e92c 100644
--- a/arch/loongarch/kernel/setup.c
+++ b/arch/loongarch/kernel/setup.c
@@ -349,10 +349,10 @@ void __init setup_arch(char **cmdline_p)

init_environ();
memblock_init();
+ pagetable_init();
parse_early_param();

platform_init();
- pagetable_init();
arch_mem_init(cmdline_p);

resource_init();
diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c
index 88c935344034..63e19b7a6644 100644
--- a/arch/loongarch/mm/init.c
+++ b/arch/loongarch/mm/init.c
@@ -201,6 +201,70 @@ void vmemmap_free(unsigned long start, unsigned long end,
#endif
#endif

+static pte_t *fixmap_pte(unsigned long addr)
+{
+ pgd_t *pgd;
+ p4d_t *p4d;
+ pud_t *pud;
+ pmd_t *pmd;
+
+ pgd = pgd_offset_k(addr);
+ p4d = p4d_offset(pgd, addr);
+
+ if (pgd_none(*pgd)) {
+ pud_t *new;
+
+ new = memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
+ pgd_populate(&init_mm, pgd, new);
+#ifndef __PAGETABLE_PUD_FOLDED
+ pud_init(new);
+#endif
+ }
+
+ pud = pud_offset(p4d, addr);
+ if (pud_none(*pud)) {
+ pmd_t *new;
+
+ new = memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
+ pud_populate(&init_mm, pud, new);
+#ifndef __PAGETABLE_PMD_FOLDED
+ pmd_init(new);
+#endif
+ }
+
+ pmd = pmd_offset(pud, addr);
+ if (pmd_none(*pmd)) {
+ pte_t *new;
+
+ new = memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
+ pmd_populate_kernel(&init_mm, pmd, new);
+ }
+
+ return pte_offset_kernel(pmd, addr);
+}
+
+void __init __set_fixmap(enum fixed_addresses idx,
+ phys_addr_t phys, pgprot_t flags)
+{
+ unsigned long addr = __fix_to_virt(idx);
+ pte_t *ptep;
+
+ BUG_ON(idx <= FIX_HOLE || idx >= __end_of_fixed_addresses);
+
+ ptep = fixmap_pte(addr);
+ if (!pte_none(*ptep)) {
+ pte_ERROR(*ptep);
+ return;
+ }
+
+ if (pgprot_val(flags))
+ set_pte(ptep, pfn_pte(phys >> PAGE_SHIFT, flags));
+ else {
+ pte_clear(&init_mm, addr, ptep);
+ flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
+ }
+}
+
/*
* Align swapper_pg_dir in to 64K, allows its address to be loaded
* with a single LUI instruction in the TLB handlers. If we used
diff --git a/arch/loongarch/pci/acpi.c b/arch/loongarch/pci/acpi.c
index bf921487333c..ac18ca7a900a 100644
--- a/arch/loongarch/pci/acpi.c
+++ b/arch/loongarch/pci/acpi.c
@@ -82,6 +82,69 @@ static int acpi_prepare_root_resources(struct acpi_pci_root_info *ci)
return 0;
}

+/*
+ * Create a PCI config space window
+ * - reserve mem region
+ * - alloc struct pci_config_window with space for all mappings
+ * - ioremap the config space
+ */
+struct pci_config_window *arch_pci_ecam_create(struct device *dev,
+ struct resource *cfgres, struct resource *busr, const struct pci_ecam_ops *ops)
+{
+ int bsz, bus_range, err;
+ struct resource *conflict;
+ struct pci_config_window *cfg;
+
+ if (busr->start > busr->end)
+ return ERR_PTR(-EINVAL);
+
+ cfg = kzalloc(sizeof(*cfg), GFP_KERNEL);
+ if (!cfg)
+ return ERR_PTR(-ENOMEM);
+
+ cfg->parent = dev;
+ cfg->ops = ops;
+ cfg->busr.start = busr->start;
+ cfg->busr.end = busr->end;
+ cfg->busr.flags = IORESOURCE_BUS;
+ bus_range = resource_size(cfgres) >> ops->bus_shift;
+
+ bsz = 1 << ops->bus_shift;
+
+ cfg->res.start = cfgres->start;
+ cfg->res.end = cfgres->end;
+ cfg->res.flags = IORESOURCE_MEM | IORESOURCE_BUSY;
+ cfg->res.name = "PCI ECAM";
+
+ conflict = request_resource_conflict(&iomem_resource, &cfg->res);
+ if (conflict) {
+ err = -EBUSY;
+ dev_err(dev, "can't claim ECAM area %pR: address conflict with %s %pR\n",
+ &cfg->res, conflict->name, conflict);
+ goto err_exit;
+ }
+
+ cfg->win = pci_remap_cfgspace(cfgres->start, bus_range * bsz);
+ if (!cfg->win)
+ goto err_exit_iomap;
+
+ if (ops->init) {
+ err = ops->init(cfg);
+ if (err)
+ goto err_exit;
+ }
+ dev_info(dev, "ECAM at %pR for %pR\n", &cfg->res, &cfg->busr);
+
+ return cfg;
+
+err_exit_iomap:
+ err = -ENOMEM;
+ dev_err(dev, "ECAM ioremap failed\n");
+err_exit:
+ pci_ecam_free(cfg);
+ return ERR_PTR(err);
+}
+
/*
* Lookup the bus range for the domain in MCFG, and set up config space
* mapping.
@@ -106,11 +169,16 @@ pci_acpi_setup_ecam_mapping(struct acpi_pci_root *root)

bus_shift = ecam_ops->bus_shift ? : 20;

- cfgres.start = root->mcfg_addr + (bus_res->start << bus_shift);
- cfgres.end = cfgres.start + (resource_size(bus_res) << bus_shift) - 1;
- cfgres.flags = IORESOURCE_MEM;
+ if (bus_shift == 20)
+ cfg = pci_ecam_create(dev, &cfgres, bus_res, ecam_ops);
+ else {
+ cfgres.start = root->mcfg_addr + (bus_res->start << bus_shift);
+ cfgres.end = cfgres.start + (resource_size(bus_res) << bus_shift) - 1;
+ cfgres.end |= BIT(28) + (((PCI_CFG_SPACE_EXP_SIZE - 1) & 0xf00) << 16);
+ cfgres.flags = IORESOURCE_MEM;
+ cfg = arch_pci_ecam_create(dev, &cfgres, bus_res, ecam_ops);
+ }

- cfg = pci_ecam_create(dev, &cfgres, bus_res, ecam_ops);
if (IS_ERR(cfg)) {
dev_err(dev, "%04x:%pR error %ld mapping ECAM\n", seg, bus_res, PTR_ERR(cfg));
return NULL;
--
2.31.1
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