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Message-ID: <1438151570.25925.121.camel@mhfsdcap03>
Date: Wed, 29 Jul 2015 14:32:50 +0800
From: Yong Wu <yong.wu@...iatek.com>
To: Robin Murphy <robin.murphy@....com>
CC: Joerg Roedel <joro@...tes.org>,
Thierry Reding <treding@...dia.com>,
Mark Rutland <Mark.Rutland@....com>,
Matthias Brugger <matthias.bgg@...il.com>,
Will Deacon <Will.Deacon@....com>,
Daniel Kurtz <djkurtz@...gle.com>,
Tomasz Figa <tfiga@...gle.com>,
Lucas Stach <l.stach@...gutronix.de>,
Rob Herring <robh+dt@...nel.org>,
Catalin Marinas <Catalin.Marinas@....com>,
"linux-mediatek@...ts.infradead.org"
<linux-mediatek@...ts.infradead.org>,
Sasha Hauer <kernel@...gutronix.de>,
"srv_heupstream@...iatek.com" <srv_heupstream@...iatek.com>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
"pebolle@...cali.nl" <pebolle@...cali.nl>,
"arnd@...db.de" <arnd@...db.de>,
"mitchelh@...eaurora.org" <mitchelh@...eaurora.org>,
"cloud.chou@...iatek.com" <cloud.chou@...iatek.com>,
"frederic.chen@...iatek.com" <frederic.chen@...iatek.com>,
<youhua.li@...iatek.com>
Subject: Re: [PATCH v3 5/6] iommu/mediatek: Add mt8173 IOMMU driver
On Mon, 2015-07-27 at 14:23 +0100, Robin Murphy wrote:
> On 16/07/15 10:04, Yong Wu wrote:
> > This patch adds support for mediatek m4u (MultiMedia Memory Management
> > Unit).
> >
> > Signed-off-by: Yong Wu <yong.wu@...iatek.com>
> [...]
> > +static void mtk_iommu_flush_pgtable(void *ptr, size_t size, void *cookie)
> > +{
> > + struct mtk_iommu_domain *domain = cookie;
> > + unsigned long offset = (unsigned long)ptr & ~PAGE_MASK;
> > +
> > + dma_map_page(domain->data->dev, virt_to_page(ptr), offset,
> > + size, DMA_TO_DEVICE);
>
> Nit: this looks like it may as well be dma_map_single.
>
> It would probably be worth following it with a matching unmap too, just
> to avoid any possible leakage bugs (especially if this M4U ever appears
> in a SoC supporting RAM above the 32-bit boundary).
About the map, I will read and try to follow your patch:
iommu/io-pgtable-arm: Allow appropriate DMA API use.
>
> > +}
> > +
> [...]
> > +static int mtk_iommu_parse_dt(struct platform_device *pdev,
> > + struct mtk_iommu_data *data)
> > +{
> > + struct device *dev = &pdev->dev;
> > + struct device_node *ofnode;
> > + struct resource *res;
> > + int i;
> > +
> > + ofnode = dev->of_node;
> > +
> > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > + data->base = devm_ioremap_resource(&pdev->dev, res);
> > + if (IS_ERR(data->base))
> > + return PTR_ERR(data->base);
> > +
> > + data->irq = platform_get_irq(pdev, 0);
> > + if (data->irq < 0)
> > + return data->irq;
> > +
> > + data->bclk = devm_clk_get(dev, "bclk");
> > + if (IS_ERR(data->bclk))
> > + return PTR_ERR(data->bclk);
> > +
> > + data->larb_nr = of_count_phandle_with_args(
> > + ofnode, "mediatek,larb", NULL);
> > + if (data->larb_nr < 0)
> > + return data->larb_nr;
> > +
> > + for (i = 0; i < data->larb_nr; i++) {
> > + struct device_node *larbnode;
> > + struct platform_device *plarbdev;
> > +
> > + larbnode = of_parse_phandle(ofnode, "mediatek,larb", i);
> > + if (!larbnode)
> > + return -EINVAL;
> > +
> > + plarbdev = of_find_device_by_node(larbnode);
> > + of_node_put(larbnode);
> > + if (!plarbdev)
> > + return -EPROBE_DEFER;
> > + data->larbdev[i] = &plarbdev->dev;
> > + }
>
> At a glance this seems like a job for of_parse_phandle_with_args, but I
> may be missing something subtle.
It seems We can not use of_parse_phandle_with_args here.
The node of larb is.
//=========
larb0: larb@...21000 {
compatible = "mediatek,mt8173-smi-larb";
reg = <0 0x14021000 0 0x1000>;
mediatek,smi = <&smi_common>;
power-domains = <&scpsys MT8173_POWER_DOMAIN_MM>;
clocks = <&mmsys CLK_MM_SMI_LARB0>,
<&mmsys CLK_MM_SMI_LARB0>;
clock-names = "apb", "smi";
};
//==========
of_parse_phandle_with_args(ofnode,"mediatek,larb", "mediatek,smi",
&larb) will be wrong due to there is no item like "mediatek,smi = <1>;"
in larb.
And this code seems to be not simple if we use
of_parse_phandle_with_args. Both need a loop.
so I don't change it here, ok?
>
> > + return 0;
> > +}
> > +
> [...]
> > +static int mtk_iommu_init_domain_context(struct mtk_iommu_domain *dom)
> > +{
> > + int ret;
> > +
> > + if (dom->iop)
> > + return 0;
> > +
> > + spin_lock_init(&dom->pgtlock);
> > + dom->cfg.quirks = IO_PGTABLE_QUIRK_ARM_NS |
> > + IO_PGTABLE_QUIRK_SHORT_SUPERSECTION |
> > + IO_PGTABLE_QUIRK_SHORT_MTK;
> > + dom->cfg.pgsize_bitmap = mtk_iommu_ops.pgsize_bitmap,
> > + dom->cfg.ias = 32;
> > + dom->cfg.oas = 32;
> > + dom->cfg.tlb = &mtk_iommu_gather_ops;
> > +
> > + dom->iop = alloc_io_pgtable_ops(ARM_SHORT_DESC, &dom->cfg, dom);
> > + if (!dom->iop) {
> > + pr_err("Failed to alloc io pgtable\n");
> > + return -EINVAL;
> > + }
> > +
> > + /* Update our support page sizes bitmap */
> > + mtk_iommu_ops.pgsize_bitmap = dom->cfg.pgsize_bitmap;
> > +
> > + ret = mtk_iommu_hw_init(dom);
> > + if (ret)
> > + free_io_pgtable_ops(dom->iop);
> > +
> > + return ret;
> > +}
>
> I don't see that you need the above function at all - since your
> pagetable config is fixed and doesn't have any depency on which IOMMU
> you're attaching to, can't you just do all of that straight away in
> domain_alloc?
Yes. We could move it into domain_alloc.
>
> > +static struct iommu_domain *mtk_iommu_domain_alloc(unsigned type)
> > +{
> > + struct mtk_iommu_domain *priv;
> > +
> > + /* We only support unmanaged domains for now */
> > + if (type != IOMMU_DOMAIN_UNMANAGED)
> > + return NULL;
>
> Have you had a chance to play with the latest DMA mapping series now
> that I've integrated the default domain changes? I think if you handled
> IOMMU_DOMAIN_DMA requests here and made them always return the
> (preallocated) private domain, you should be able to get rid of the
> tricks in attach_device completely.
I can change it to this:
if (type != IOMMU_DOMAIN_UNMANAGED && type != IOMMU_DOMAIN_DMA)
return NULL;
If always return the (preallocated) private domain, I have to use a
global variable to restore the preallocated domain here!.
And It also will print "Incompatible range for DMA domain" and return
fail.
Could we return 0 instead of -EFAULT in iommu_dma_init_domain if the
domain is the same.
> > + priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> > + if (!priv)
> > + return NULL;
> > +
> > + priv->domain.geometry.aperture_start = 0;
> > + priv->domain.geometry.aperture_end = (1ULL << 32) - 1;
>
> DMA_BIT_MASK(32) ?
Thanks.
>
> > + priv->domain.geometry.force_aperture = true;
> > +
> > + return &priv->domain;
> > +}
> > +
> [...]
> > +static int mtk_iommu_add_device(struct device *dev)
> > +{
> > + struct mtk_iommu_domain *mtkdom;
> > + struct iommu_group *group;
> > + struct mtk_iommu_client_priv *devhead;
> > + int ret;
> > +
> > + if (!dev->archdata.dma_ops)/* Not a iommu client device */
> > + return -ENODEV;
>
> I think archdata.dma_ops is the wrong thing to test here. It would be
> better to use archdata.iommu, since you go on to dereference that
> unconditionally anyway, plus then you only depend on your own of_xlate
> behaviour, rather than some quirk of the arch code (which could quietly
> change in future).
I will change archdata.iommu next time.
Current I used the dev->archdata.iommu of the iommu device(m4u device)
itself. then the m4u device will come here too. so I changed to
dev->archdata.dma_ops.
As before, If we use a global variable for the mtk_iommu_domain, we
could use archdata.iommu here.
>
> > + group = iommu_group_get(dev);
> > + if (!group) {
> > + group = iommu_group_alloc();
> > + if (IS_ERR(group)) {
> > + dev_err(dev, "Failed to allocate IOMMU group\n");
> > + return PTR_ERR(group);
> > + }
> > + }
> > +
> > + ret = iommu_group_add_device(group, dev);
> > + if (ret) {
> > + dev_err(dev, "Failed to add IOMMU group\n");
> > + goto err_group_put;
> > + }
> > +
> > + /* get the mtk_iommu_domain from the iommu device */
> > + devhead = dev->archdata.iommu;
> > + mtkdom = devhead->imudev->archdata.iommu;
> > + ret = iommu_attach_group(&mtkdom->domain, group);
> > + if (ret)
> > + dev_err(dev, "Failed to attach IOMMU group\n");
> > +
> > +err_group_put:
> > + iommu_group_put(group);
> > + return ret;
> > +}
> > +
> [...]
> > +static struct iommu_ops mtk_iommu_ops = {
> > + .domain_alloc = mtk_iommu_domain_alloc,
> > + .domain_free = mtk_iommu_domain_free,
> > + .attach_dev = mtk_iommu_attach_device,
> > + .detach_dev = mtk_iommu_detach_device,
> > + .map = mtk_iommu_map,
> > + .unmap = mtk_iommu_unmap,
> > + .map_sg = default_iommu_map_sg,
> > + .iova_to_phys = mtk_iommu_iova_to_phys,
> > + .add_device = mtk_iommu_add_device,
> > + .of_xlate = mtk_iommu_of_xlate,
> > + .pgsize_bitmap = -1UL,
>
> As above, if you know the hardware only supports a single descriptor
> format with a fixed set of page sizes, why not just represent that directly?
OK. I will write the fix page sizes here.
I wrote it following the arm-smmu.c:)
>
> > +};
> > +
> [...]
> > +static int mtk_iommu_suspend(struct device *dev)
> > +{
> > + struct mtk_iommu_domain *mtkdom = dev_get_drvdata(dev);
> > + struct mtk_iommu_data *data = mtkdom->data;
> > + void __iomem *base = data->base;
> > + unsigned int i = 0;
> > +
> > + data->reg[i++] = readl(base + REG_MMU_PT_BASE_ADDR);
>
> Redundancy nit: any particular reason for saving this here rather than
> simply restoring it from mtkdom->cfg.arm_short_cfg.ttbr[0] on resume?
>
> > + data->reg[i++] = readl(base + REG_MMU_STANDARD_AXI_MODE);
> > + data->reg[i++] = readl(base + REG_MMU_DCM_DIS);
> > + data->reg[i++] = readl(base + REG_MMU_CTRL_REG);
> > + data->reg[i++] = readl(base + REG_MMU_IVRP_PADDR);
> > + data->reg[i++] = readl(base + REG_MMU_INT_CONTROL0);
> > + data->reg[i++] = readl(base + REG_MMU_INT_MAIN_CONTROL);
>
> Nit: given that these are fairly arbitrary discontiguous registers so
> you can't have a simple loop over the array, it might be clearer to
> replace the array with an equivalent struct, e.g.:
>
> struct mtk_iommu_suspend_regs {
> u32 standard_axi_mode;
> u32 dcm_dis;
> ...
> }
>
> ...
> data->reg.dcm_dis = readl(base + REG_MMU_DCM_DIS);
> ...
>
> then since you refer to everything by name you don't have to worry about
> the length and order of array elements if anything ever changes.
Good idea. Thanks very much.
>
> > + return 0;
> > +}
> > +
> > +static int mtk_iommu_resume(struct device *dev)
> > +{
> > + struct mtk_iommu_domain *mtkdom = dev_get_drvdata(dev);
> > + struct mtk_iommu_data *data = mtkdom->data;
> > + void __iomem *base = data->base;
> > + unsigned int i = 0;
> > +
> > + writel(data->reg[i++], base + REG_MMU_PT_BASE_ADDR);
> > + writel(data->reg[i++], base + REG_MMU_STANDARD_AXI_MODE);
> > + writel(data->reg[i++], base + REG_MMU_DCM_DIS);
> > + writel(data->reg[i++], base + REG_MMU_CTRL_REG);
> > + writel(data->reg[i++], base + REG_MMU_IVRP_PADDR);
> > + writel(data->reg[i++], base + REG_MMU_INT_CONTROL0);
> > + writel(data->reg[i++], base + REG_MMU_INT_MAIN_CONTROL);
> > + return 0;
> > +}
>
> Other than that though, modulo the issues with the pagetable code I
> think this part of the driver is shaping up quite nicely.
>
> Robin.
>
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