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Message-ID: <72c979bd-501f-df9b-7bca-02b8c11d3860@arm.com>
Date: Thu, 21 Jan 2021 12:50:51 +0000
From: Robin Murphy <robin.murphy@....com>
To: "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>,
Will Deacon <will@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Joerg Roedel <joro@...tes.org>,
linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
iommu <iommu@...ts.linux-foundation.org>,
linux-kernel <linux-kernel@...r.kernel.org>
Cc: Jean-Philippe Brucker <jean-philippe@...aro.org>,
Shameer Kolothum <shameerali.kolothum.thodi@...wei.com>
Subject: Re: [PATCH 2/2] Revert "iommu/arm-smmu-v3: Don't reserve
implementation defined register space"
On 2021-01-21 02:04, Leizhen (ThunderTown) wrote:
>
>
> On 2021/1/20 23:02, Robin Murphy wrote:
>> On 2021-01-19 01:59, Zhen Lei wrote:
>>> This reverts commit 52f3fab0067d6fa9e99c1b7f63265dd48ca76046.
>>>
>>> This problem has been fixed by another patch. The original method had side
>>> effects, it was not mapped to the user-specified resource size. The code
>>> will become more complex when ECMDQ is supported later.
>>
>> FWIW I don't think that's a significant issue either way - there could be any number of imp-def pages between SMMU page 0 and the ECMDQ control pages, so it will still be logical to map them as another separate thing anyway.
>
> Yes, so now I'm thinking of preserving the SMMUv3 resources and eliminating the imp-def area. Then use another devm_ioremap() to cover the entire resource，assign it to smmu->base.
> Otherwise, a base pointer needs to be defined for each separated register space，or call a function to convert each time.
But we'll almost certainly want to maintain a pointer to start of the
ECMDQ control page block anyway, since that's not fixed relative to
smmu->base. Therefore what's the harm in handling that via a dedicated
mapping, once we've determined that we *do* intend to use ECMDQs?
Otherwise we end up with in the complicated dance of trying to map
"everything" up-front in order to be able to read the ID registers to
determine what the actual extent of "everything" is supposed to be.
(also this reminds me that I was going to remove arm_smmu_page1_fixup()
entirely - I'd totally forgotten about that...)
Robin.
>>> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
>>> ---
>>> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 32 ++++-------------------------
>>> drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 3 ---
>>> 2 files changed, 4 insertions(+), 31 deletions(-)
>>>
>>> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>>> index 8ca7415d785d9bf..477f473842e5272 100644
>>> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>>> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>>> @@ -91,8 +91,9 @@ struct arm_smmu_option_prop {
>>> static inline void __iomem *arm_smmu_page1_fixup(unsigned long offset,
>>> struct arm_smmu_device *smmu)
>>> {
>>> - if (offset > SZ_64K)
>>> - return smmu->page1 + offset - SZ_64K;
>>> + if ((offset > SZ_64K) &&
>>> + (smmu->options & ARM_SMMU_OPT_PAGE0_REGS_ONLY))
>>> + offset -= SZ_64K;
>>> return smmu->base + offset;
>>> }
>>> @@ -3486,18 +3487,6 @@ static int arm_smmu_set_bus_ops(struct iommu_ops *ops)
>>> return err;
>>> }
>>> -static void __iomem *arm_smmu_ioremap(struct device *dev, resource_size_t start,
>>> - resource_size_t size)
>>> -{
>>> - struct resource res = {
>>> - .flags = IORESOURCE_MEM,
>>> - .start = start,
>>> - .end = start + size - 1,
>>> - };
>>> -
>>> - return devm_ioremap_resource(dev, &res);
>>> -}
>>> -
>>> static int arm_smmu_device_probe(struct platform_device *pdev)
>>> {
>>> int irq, ret;
>>> @@ -3533,23 +3522,10 @@ static int arm_smmu_device_probe(struct platform_device *pdev)
>>> }
>>> ioaddr = res->start;
>>> - /*
>>> - * Don't map the IMPLEMENTATION DEFINED regions, since they may contain
>>> - * the PMCG registers which are reserved by the PMU driver.
>>> - */
>>> - smmu->base = arm_smmu_ioremap(dev, ioaddr, ARM_SMMU_REG_SZ);
>>> + smmu->base = devm_ioremap_resource(dev, res);
>>> if (IS_ERR(smmu->base))
>>> return PTR_ERR(smmu->base);
>>> - if (arm_smmu_resource_size(smmu) > SZ_64K) {
>>> - smmu->page1 = arm_smmu_ioremap(dev, ioaddr + SZ_64K,
>>> - ARM_SMMU_REG_SZ);
>>> - if (IS_ERR(smmu->page1))
>>> - return PTR_ERR(smmu->page1);
>>> - } else {
>>> - smmu->page1 = smmu->base;
>>> - }
>>> -
>>> /* Interrupt lines */
>>> irq = platform_get_irq_byname_optional(pdev, "combined");
>>> diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
>>> index 96c2e9565e00282..0c3090c60840c22 100644
>>> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
>>> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
>>> @@ -152,8 +152,6 @@
>>> #define ARM_SMMU_PRIQ_IRQ_CFG1 0xd8
>>> #define ARM_SMMU_PRIQ_IRQ_CFG2 0xdc
>>> -#define ARM_SMMU_REG_SZ 0xe00
>>> -
>>> /* Common MSI config fields */
>>> #define MSI_CFG0_ADDR_MASK GENMASK_ULL(51, 2)
>>> #define MSI_CFG2_SH GENMASK(5, 4)
>>> @@ -584,7 +582,6 @@ struct arm_smmu_strtab_cfg {
>>> struct arm_smmu_device {
>>> struct device *dev;
>>> void __iomem *base;
>>> - void __iomem *page1;
>>> #define ARM_SMMU_FEAT_2_LVL_STRTAB (1 << 0)
>>> #define ARM_SMMU_FEAT_2_LVL_CDTAB (1 << 1)
>>>
>>
>> .
>>
>
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