From 98ea2dba65932ffc456b6d7b11b8a0624e2f7b95 Mon Sep 17 00:00:00 2001 From: Thomas Petazzoni Date: Fri, 13 Jun 2014 10:58:38 +0100 Subject: ARM: 8076/1: mm: add support for HW coherent systems in PL310 cache When a PL310 cache is used on a system that provides hardware coherency, the outer cache sync operation is useless, and can be skipped. Moreover, on some systems, it is harmful as it causes deadlocks between the Marvell coherency mechanism, the Marvell PCIe controller and the Cortex-A9. To avoid this, this commit introduces a new Device Tree property 'arm,io-coherent' for the L2 cache controller node, valid only for the PL310 cache. It identifies the usage of the PL310 cache in an I/O coherent configuration. Internally, it makes the driver disable the outer cache sync operation. Note that technically speaking, a fully coherent system wouldn't require any of the other .outer_cache operations. However, in practice, when booting secondary CPUs, these are not yet coherent, and therefore a set of cache maintenance operations are necessary at this point. This explains why we keep the other .outer_cache operations and only ->sync is disabled. While in theory any write to a PL310 register could cause the deadlock, in practice, disabling ->sync is sufficient to workaround the deadlock, since the other cache maintenance operations are only used in very specific situations. Contrary to previous versions of this patch, this new version does not simply NULL-ify the ->sync member, because the l2c_init_data structures are now 'const' and therefore cannot be modified, which is a good thing. Therefore, this patch introduces a separate l2c_init_data instance, called of_l2c310_coherent_data. Signed-off-by: Thomas Petazzoni Signed-off-by: Russell King --- arch/arm/mm/cache-l2x0.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'arch/arm/mm/cache-l2x0.c') diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c index efc5cabf70e0..076172b69422 100644 --- a/arch/arm/mm/cache-l2x0.c +++ b/arch/arm/mm/cache-l2x0.c @@ -1068,6 +1068,33 @@ static const struct l2c_init_data of_l2c310_data __initconst = { }, }; +/* + * This is a variant of the of_l2c310_data with .sync set to + * NULL. Outer sync operations are not needed when the system is I/O + * coherent, and potentially harmful in certain situations (PCIe/PL310 + * deadlock on Armada 375/38x due to hardware I/O coherency). The + * other operations are kept because they are infrequent (therefore do + * not cause the deadlock in practice) and needed for secondary CPU + * boot and other power management activities. + */ +static const struct l2c_init_data of_l2c310_coherent_data __initconst = { + .type = "L2C-310 Coherent", + .way_size_0 = SZ_8K, + .num_lock = 8, + .of_parse = l2c310_of_parse, + .enable = l2c310_enable, + .fixup = l2c310_fixup, + .save = l2c310_save, + .outer_cache = { + .inv_range = l2c210_inv_range, + .clean_range = l2c210_clean_range, + .flush_range = l2c210_flush_range, + .flush_all = l2c210_flush_all, + .disable = l2c310_disable, + .resume = l2c310_resume, + }, +}; + /* * Note that the end addresses passed to Linux primitives are * noninclusive, while the hardware cache range operations use @@ -1487,6 +1514,10 @@ int __init l2x0_of_init(u32 aux_val, u32 aux_mask) data = of_match_node(l2x0_ids, np)->data; + if (of_device_is_compatible(np, "arm,pl310-cache") && + of_property_read_bool(np, "arm,io-coherent")) + data = &of_l2c310_coherent_data; + old_aux = readl_relaxed(l2x0_base + L2X0_AUX_CTRL); if (old_aux != ((old_aux & aux_mask) | aux_val)) { pr_warn("L2C: platform modifies aux control register: 0x%08x -> 0x%08x\n", -- cgit v1.2.3 From 9a2c33a422d60e8e55c5aff6752522dc39993b16 Mon Sep 17 00:00:00 2001 From: Russell King Date: Mon, 7 Jul 2014 13:53:03 +0100 Subject: ARM: l2c: fix revision checking The revision checking in l2c310_enable() was not correct; we were masking the part number rather than the revision number. Fix this to use the correct macro. Fixes: 4374d64933b1 ("ARM: l2c: add automatic enable of early BRESP") Signed-off-by: Russell King --- arch/arm/mm/cache-l2x0.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/arm/mm/cache-l2x0.c') diff --git a/arch/arm/mm/cache-l2x0.c b/arch/arm/mm/cache-l2x0.c index 076172b69422..7c3fb41a462e 100644 --- a/arch/arm/mm/cache-l2x0.c +++ b/arch/arm/mm/cache-l2x0.c @@ -664,7 +664,7 @@ static int l2c310_cpu_enable_flz(struct notifier_block *nb, unsigned long act, v static void __init l2c310_enable(void __iomem *base, u32 aux, unsigned num_lock) { - unsigned rev = readl_relaxed(base + L2X0_CACHE_ID) & L2X0_CACHE_ID_PART_MASK; + unsigned rev = readl_relaxed(base + L2X0_CACHE_ID) & L2X0_CACHE_ID_RTL_MASK; bool cortex_a9 = read_cpuid_part_number() == ARM_CPU_PART_CORTEX_A9; if (rev >= L310_CACHE_ID_RTL_R2P0) { -- cgit v1.2.3