From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756227AbcECQuY (ORCPT ); Tue, 3 May 2016 12:50:24 -0400 Received: from foss.arm.com ([217.140.101.70]:40244 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756120AbcECQuX (ORCPT ); Tue, 3 May 2016 12:50:23 -0400 Subject: Re: [PATCH V2] iommu/arm-smmu: clear cache lock bit of ACR To: Peng Fan , will.deacon@arm.com References: <1462283430-9559-1-git-send-email-van.freenix@gmail.com> Cc: joro@8bytes.org, linux-arm-kernel@lists.infradead.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org From: Robin Murphy Message-ID: <5728D6CB.3010003@arm.com> Date: Tue, 3 May 2016 17:50:19 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.2 MIME-Version: 1.0 In-Reply-To: <1462283430-9559-1-git-send-email-van.freenix@gmail.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/05/16 14:50, Peng Fan wrote: > According MMU-500r2 TRM, section 3.7.1 Auxiliary Control registers, > You can modify ACTLR only when the ACR.CACHE_LOCK bit is 0. > > So before clearing ARM_MMU500_ACTLR_CPRE of each context bank, > need clear CACHE_LOCK bit of ACR register first. > > Since CACHE_LOCK bit is only present in MMU-500r2 onwards, > need to check the major number of IDR7. > > Signed-off-by: Peng Fan > Cc: Will Deacon > Cc: Robin Murphy > --- > > V2: > Following Robin's comments, need to check IDR7 before clearing > CACHE_LOCK bit of ACR. > > V1: > Patch based on iommu/devel > > drivers/iommu/arm-smmu.c | 23 ++++++++++++++++++++++- > 1 file changed, 22 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c > index acff332..c7ad23e 100644 > --- a/drivers/iommu/arm-smmu.c > +++ b/drivers/iommu/arm-smmu.c > @@ -98,6 +98,9 @@ > #define sCR0_BSU_SHIFT 14 > #define sCR0_BSU_MASK 0x3 > > +/* Auxiliary Configuration register */ > +#define ARM_SMMU_GR0_sACR 0x10 > + > /* Identification registers */ > #define ARM_SMMU_GR0_ID0 0x20 > #define ARM_SMMU_GR0_ID1 0x24 > @@ -144,6 +147,9 @@ > #define ID2_PTFS_64K (1 << 14) > #define ID2_VMID16 (1 << 15) > > +#define ID7_MAJOR_SHIFT 4 > +#define ID7_MAJOR_MASK 0xf > + > /* Global TLB invalidation */ > #define ARM_SMMU_GR0_TLBIVMID 0x64 > #define ARM_SMMU_GR0_TLBIALLNSNH 0x68 > @@ -235,6 +241,8 @@ > > #define ARM_MMU500_ACTLR_CPRE (1 << 1) > > +#define ARM_MMU500_ACR_CACHE_LOCK (1 << 26) > + > #define CB_PAR_F (1 << 0) > > #define ATSR_ACTIVE (1 << 0) > @@ -1493,7 +1501,7 @@ static void arm_smmu_device_reset(struct arm_smmu_device *smmu) > void __iomem *gr0_base = ARM_SMMU_GR0(smmu); > void __iomem *cb_base; > int i = 0; > - u32 reg; > + u32 reg, major; > > /* clear global FSR */ > reg = readl_relaxed(ARM_SMMU_GR0_NS(smmu) + ARM_SMMU_GR0_sGFSR); > @@ -1506,6 +1514,19 @@ static void arm_smmu_device_reset(struct arm_smmu_device *smmu) > writel_relaxed(reg, gr0_base + ARM_SMMU_GR0_S2CR(i)); > } > > + /* > + * Before clearing ARM_MMU500_ACTLR_CPRE, need to > + * clear CACHE_LOCK bit of ACR first. And, CACHE_LOCK > + * bit is only present in MMU-500r2 onwards. > + */ > + reg = readl_relaxed(gr0_base + ARM_SMMU_GR0_ID7); > + major = (reg >> ID7_MAJOR_SHIFT) & ID7_MAJOR_MASK; > + if ((smmu->model == ARM_MMU500) && (major >= 2)) { > + reg = readl_relaxed(gr0_base + ARM_SMMU_GR0_sACR); > + reg &= ~ARM_MMU500_ACR_CACHE_LOCK; > + writel_relaxed(reg, gr0_base + ARM_SMMU_GR0_sACR); > + } > + I'd have been inclined to make the ID reg read conditional on ARM_MMU500 as well, but this way is marginally more compact, and it's not like we're in a frequently-used hot path anyway. Reviewed-by: Robin Murphy Thanks, Robin. > /* Make sure all context banks are disabled and clear CB_FSR */ > for (i = 0; i < smmu->num_context_banks; ++i) { > cb_base = ARM_SMMU_CB_BASE(smmu) + ARM_SMMU_CB(smmu, i); >