From 2820a708d5a321342bef34e459fdc8679c30e20f Mon Sep 17 00:00:00 2001 From: Eugeniy Paltsev Date: Mon, 30 Jul 2018 19:26:34 +0300 Subject: ARC: dma [IOC] Enable per device io coherency So far the IOC treatment was global on ARC, being turned on (or off) for all devices in the system. With this patch, this can now be done per device using the "dma-coherent" DT property; IOW with this patch we can use both HW-coherent and regular DMA peripherals simultaneously. The changes involved are too many so enlisting the summary below: 1. common code calls ARC arch_setup_dma_ops() per device. 2. For coherent dma (IOC) it plugs in generic @dma_direct_ops which doesn't need any arch specific backend: No need for any explicit cache flushes or MMU mappings to provide for uncached access - dma_(map|sync)_single* return early as corresponding dma ops callbacks are NULL in generic code. So arch_sync_dma_*() -> dma_cache_*() need not handle the coherent dma case, hence drop ARC __dma_cache_*_ioc() which were no-op anyways 3. For noncoherent dma (non IOC) generic @dma_noncoherent_ops is used which in turns calls ARC specific routines - arch_dma_alloc() no longer checks for @ioc_enable since this is called only for !IOC case. Reviewed-by: Christoph Hellwig Signed-off-by: Eugeniy Paltsev Signed-off-by: Vineet Gupta [vgupta: rewrote changelog] --- arch/arc/mm/cache.c | 23 ++++++++--------------- 1 file changed, 8 insertions(+), 15 deletions(-) (limited to 'arch/arc/mm/cache.c') diff --git a/arch/arc/mm/cache.c b/arch/arc/mm/cache.c index 25c631942500..2d389cab46ba 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; } @@ -896,15 +896,6 @@ static void __dma_cache_wback_slc(phys_addr_t start, unsigned long sz) slc_op(start, sz, OP_FLUSH); } -/* - * 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 */ @@ -1264,11 +1255,7 @@ 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 +1264,12 @@ 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) -- cgit From 2b720e99a1297417b979bf4810a0f01d27133c48 Mon Sep 17 00:00:00 2001 From: Eugeniy Paltsev Date: Mon, 30 Jul 2018 19:26:35 +0300 Subject: ARC: IOC: panic if both IOC and ZONE_HIGHMEM enabled Signed-off-by: Eugeniy Paltsev Signed-off-by: Vineet Gupta --- arch/arc/mm/cache.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) (limited to 'arch/arc/mm/cache.c') diff --git a/arch/arc/mm/cache.c b/arch/arc/mm/cache.c index 2d389cab46ba..f2701c13a66b 100644 --- a/arch/arc/mm/cache.c +++ b/arch/arc/mm/cache.c @@ -1144,6 +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(); -- cgit