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-rw-r--r--arch/arc/mm/cache.c36
-rw-r--r--arch/arc/mm/dma.c82
2 files changed, 62 insertions, 56 deletions
diff --git a/arch/arc/mm/cache.c b/arch/arc/mm/cache.c
index 25c631942500..f2701c13a66b 100644
--- a/arch/arc/mm/cache.c
+++ b/arch/arc/mm/cache.c
@@ -65,7 +65,7 @@ char *arc_cache_mumbojumbo(int c, char *buf, int len)
n += scnprintf(buf + n, len - n, "Peripherals\t: %#lx%s%s\n",
perip_base,
- IS_AVAIL3(ioc_exists, ioc_enable, ", IO-Coherency "));
+ IS_AVAIL3(ioc_exists, ioc_enable, ", IO-Coherency (per-device) "));
return buf;
}
@@ -897,15 +897,6 @@ static void __dma_cache_wback_slc(phys_addr_t start, unsigned long sz)
}
/*
- * DMA ops for systems with IOC
- * IOC hardware snoops all DMA traffic keeping the caches consistent with
- * memory - eliding need for any explicit cache maintenance of DMA buffers
- */
-static void __dma_cache_wback_inv_ioc(phys_addr_t start, unsigned long sz) {}
-static void __dma_cache_inv_ioc(phys_addr_t start, unsigned long sz) {}
-static void __dma_cache_wback_ioc(phys_addr_t start, unsigned long sz) {}
-
-/*
* Exported DMA API
*/
void dma_cache_wback_inv(phys_addr_t start, unsigned long sz)
@@ -1153,6 +1144,19 @@ noinline void __init arc_ioc_setup(void)
{
unsigned int ioc_base, mem_sz;
+ /*
+ * As for today we don't support both IOC and ZONE_HIGHMEM enabled
+ * simultaneously. This happens because as of today IOC aperture covers
+ * only ZONE_NORMAL (low mem) and any dma transactions outside this
+ * region won't be HW coherent.
+ * If we want to use both IOC and ZONE_HIGHMEM we can use
+ * bounce_buffer to handle dma transactions to HIGHMEM.
+ * Also it is possible to modify dma_direct cache ops or increase IOC
+ * aperture size if we are planning to use HIGHMEM without PAE.
+ */
+ if (IS_ENABLED(CONFIG_HIGHMEM))
+ panic("IOC and HIGHMEM can't be used simultaneously");
+
/* Flush + invalidate + disable L1 dcache */
__dc_disable();
@@ -1264,11 +1268,7 @@ void __init arc_cache_init_master(void)
if (is_isa_arcv2() && ioc_enable)
arc_ioc_setup();
- if (is_isa_arcv2() && ioc_enable) {
- __dma_cache_wback_inv = __dma_cache_wback_inv_ioc;
- __dma_cache_inv = __dma_cache_inv_ioc;
- __dma_cache_wback = __dma_cache_wback_ioc;
- } else if (is_isa_arcv2() && l2_line_sz && slc_enable) {
+ if (is_isa_arcv2() && l2_line_sz && slc_enable) {
__dma_cache_wback_inv = __dma_cache_wback_inv_slc;
__dma_cache_inv = __dma_cache_inv_slc;
__dma_cache_wback = __dma_cache_wback_slc;
@@ -1277,6 +1277,12 @@ void __init arc_cache_init_master(void)
__dma_cache_inv = __dma_cache_inv_l1;
__dma_cache_wback = __dma_cache_wback_l1;
}
+ /*
+ * In case of IOC (say IOC+SLC case), pointers above could still be set
+ * but end up not being relevant as the first function in chain is not
+ * called at all for @dma_direct_ops
+ * arch_sync_dma_for_cpu() -> dma_cache_*() -> __dma_cache_*()
+ */
}
void __ref arc_cache_init(void)
diff --git a/arch/arc/mm/dma.c b/arch/arc/mm/dma.c
index ec47e6079f5d..c75d5c3470e3 100644
--- a/arch/arc/mm/dma.c
+++ b/arch/arc/mm/dma.c
@@ -6,20 +6,17 @@
* published by the Free Software Foundation.
*/
-/*
- * DMA Coherent API Notes
- *
- * I/O is inherently non-coherent on ARC. So a coherent DMA buffer is
- * implemented by accessing it using a kernel virtual address, with
- * Cache bit off in the TLB entry.
- *
- * The default DMA address == Phy address which is 0x8000_0000 based.
- */
-
#include <linux/dma-noncoherent.h>
#include <asm/cache.h>
#include <asm/cacheflush.h>
+/*
+ * ARCH specific callbacks for generic noncoherent DMA ops (dma/noncoherent.c)
+ * - hardware IOC not available (or "dma-coherent" not set for device in DT)
+ * - But still handle both coherent and non-coherent requests from caller
+ *
+ * For DMA coherent hardware (IOC) generic code suffices
+ */
void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
gfp_t gfp, unsigned long attrs)
{
@@ -27,42 +24,29 @@ void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle,
struct page *page;
phys_addr_t paddr;
void *kvaddr;
- int need_coh = 1, need_kvaddr = 0;
-
- page = alloc_pages(gfp, order);
- if (!page)
- return NULL;
+ bool need_coh = !(attrs & DMA_ATTR_NON_CONSISTENT);
/*
- * IOC relies on all data (even coherent DMA data) being in cache
- * Thus allocate normal cached memory
- *
- * The gains with IOC are two pronged:
- * -For streaming data, elides need for cache maintenance, saving
- * cycles in flush code, and bus bandwidth as all the lines of a
- * buffer need to be flushed out to memory
- * -For coherent data, Read/Write to buffers terminate early in cache
- * (vs. always going to memory - thus are faster)
+ * __GFP_HIGHMEM flag is cleared by upper layer functions
+ * (in include/linux/dma-mapping.h) so we should never get a
+ * __GFP_HIGHMEM here.
*/
- if ((is_isa_arcv2() && ioc_enable) ||
- (attrs & DMA_ATTR_NON_CONSISTENT))
- need_coh = 0;
+ BUG_ON(gfp & __GFP_HIGHMEM);
- /*
- * - A coherent buffer needs MMU mapping to enforce non-cachability
- * - A highmem page needs a virtual handle (hence MMU mapping)
- * independent of cachability
- */
- if (PageHighMem(page) || need_coh)
- need_kvaddr = 1;
+ page = alloc_pages(gfp, order);
+ if (!page)
+ return NULL;
/* This is linear addr (0x8000_0000 based) */
paddr = page_to_phys(page);
*dma_handle = paddr;
- /* This is kernel Virtual address (0x7000_0000 based) */
- if (need_kvaddr) {
+ /*
+ * A coherent buffer needs MMU mapping to enforce non-cachability.
+ * kvaddr is kernel Virtual address (0x7000_0000 based).
+ */
+ if (need_coh) {
kvaddr = ioremap_nocache(paddr, size);
if (kvaddr == NULL) {
__free_pages(page, order);
@@ -93,12 +77,8 @@ void arch_dma_free(struct device *dev, size_t size, void *vaddr,
{
phys_addr_t paddr = dma_handle;
struct page *page = virt_to_page(paddr);
- int is_non_coh = 1;
-
- is_non_coh = (attrs & DMA_ATTR_NON_CONSISTENT) ||
- (is_isa_arcv2() && ioc_enable);
- if (PageHighMem(page) || !is_non_coh)
+ if (!(attrs & DMA_ATTR_NON_CONSISTENT))
iounmap((void __force __iomem *)vaddr);
__free_pages(page, get_order(size));
@@ -185,3 +165,23 @@ void arch_sync_dma_for_cpu(struct device *dev, phys_addr_t paddr,
break;
}
}
+
+/*
+ * Plug in coherent or noncoherent dma ops
+ */
+void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
+ const struct iommu_ops *iommu, bool coherent)
+{
+ /*
+ * IOC hardware snoops all DMA traffic keeping the caches consistent
+ * with memory - eliding need for any explicit cache maintenance of
+ * DMA buffers - so we can use dma_direct cache ops.
+ */
+ if (is_isa_arcv2() && ioc_enable && coherent) {
+ set_dma_ops(dev, &dma_direct_ops);
+ dev_info(dev, "use dma_direct_ops cache ops\n");
+ } else {
+ set_dma_ops(dev, &dma_noncoherent_ops);
+ dev_info(dev, "use dma_noncoherent_ops cache ops\n");
+ }
+}