iommu/mediatek: Move attach_device after iommu-group is ready for M4Uv1

In the commit 05f80300dc8b ("iommu: Finish making iommu_group support
mandatory"), the iommu framework has supposed all the iommu drivers have
their owner iommu-group, it get rid of the FIXME workarounds while the
group is NULL. But the flow of Mediatek M4U gen1 looks a bit trick that
it will hang at this case:

==========================================
Unable to handle kernel NULL pointer dereference at virtual address 00000030
pgd = c0004000
[00000030] *pgd=00000000
PC is at mutex_lock+0x28/0x54
LR is at iommu_attach_device+0xa4/0xd4
pc : [<c07632e8>]    lr : [<c04736fc>]    psr: 60000013
sp : df0edbb8  ip : df0edbc8  fp : df0edbc4
r10: c114da14  r9 : df2a3e40  r8 : 00000003
r7 : df27a210  r6 : df2a90c4  r5 : 00000030  r4 : 00000000
r3 : df0f8000  r2 : fffff000  r1 : df29c610  r0 : 00000030
Flags: nZCv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
xxx
(mutex_lock) from [<c04736fc>] (iommu_attach_device+0xa4/0xd4)
(iommu_attach_device) from [<c011b9dc>] (__arm_iommu_attach_device+0x28/0x90)
(__arm_iommu_attach_device) from [<c011ba60>] (arm_iommu_attach_device+0x1c/0x30)
(arm_iommu_attach_device) from [<c04759ac>] (mtk_iommu_add_device+0xfc/0x214)
(mtk_iommu_add_device) from [<c0472aa4>] (add_iommu_group+0x3c/0x68)
(add_iommu_group) from [<c047d044>] (bus_for_each_dev+0x78/0xac)
(bus_for_each_dev) from [<c04734a4>] (bus_set_iommu+0xb0/0xec)
(bus_set_iommu) from [<c0476310>] (mtk_iommu_probe+0x328/0x368)
(mtk_iommu_probe) from [<c048189c>] (platform_drv_probe+0x5c/0xc0)
(platform_drv_probe) from [<c047f510>] (driver_probe_device+0x2f4/0x4d8)
(driver_probe_device) from [<c047f800>] (__driver_attach+0x10c/0x128)
(__driver_attach) from [<c047d044>] (bus_for_each_dev+0x78/0xac)
(bus_for_each_dev) from [<c047ec78>] (driver_attach+0x2c/0x30)
(driver_attach) from [<c047e640>] (bus_add_driver+0x1e0/0x278)
(bus_add_driver) from [<c048052c>] (driver_register+0x88/0x108)
(driver_register) from [<c04817ec>] (__platform_driver_register+0x50/0x58)
(__platform_driver_register) from [<c0b31380>] (m4u_init+0x24/0x28)
(m4u_init) from [<c0101c38>] (do_one_initcall+0xf0/0x17c)
=========================

The root cause is that the device's iommu-group is NULL while
arm_iommu_attach_device is called. This patch prepare a new iommu-group
for the iommu consumer devices to fix this issue.

CC: Robin Murphy <robin.murphy@arm.com>
CC: Honghui Zhang <honghui.zhang@mediatek.com>
Fixes: 05f80300dc8b ("iommu: Finish making iommu_group support mandatory")
Reported-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
index 542930cd183d07ba1af592f2a99292a6e6c572f9..1b1b775948970ec38d20bd41d868341ce5c07b7d 100644 (file)
--- a/drivers/iommu/mtk_iommu_v1.c
+++ b/drivers/iommu/mtk_iommu_v1.c
@@ -418,20 +418,12 @@ static int mtk_iommu_create_mapping(struct device *dev,
                m4udev->archdata.iommu = mtk_mapping;
        }
 
-       ret = arm_iommu_attach_device(dev, mtk_mapping);
-       if (ret)
-               goto err_release_mapping;
-
        return 0;
-
-err_release_mapping:
-       arm_iommu_release_mapping(mtk_mapping);
-       m4udev->archdata.iommu = NULL;
-       return ret;
 }
 
 static int mtk_iommu_add_device(struct device *dev)
 {
+       struct dma_iommu_mapping *mtk_mapping;
        struct of_phandle_args iommu_spec;
        struct of_phandle_iterator it;
        struct mtk_iommu_data *data;
@@ -452,15 +444,30 @@ static int mtk_iommu_add_device(struct device *dev)
        if (!dev->iommu_fwspec || dev->iommu_fwspec->ops != &mtk_iommu_ops)
                return -ENODEV; /* Not a iommu client device */
 
-       data = dev->iommu_fwspec->iommu_priv;
-       iommu_device_link(&data->iommu, dev);
-
-       group = iommu_group_get_for_dev(dev);
+       /*
+        * This is a short-term bodge because the ARM DMA code doesn't
+        * understand multi-device groups, but we have to call into it
+        * successfully (and not just rely on a normal IOMMU API attach
+        * here) in order to set the correct DMA API ops on @dev.
+        */
+       group = iommu_group_alloc();
        if (IS_ERR(group))
                return PTR_ERR(group);
 
+       err = iommu_group_add_device(group, dev);
        iommu_group_put(group);
-       return 0;
+       if (err)
+               return err;
+
+       data = dev->iommu_fwspec->iommu_priv;
+       mtk_mapping = data->dev->archdata.iommu;
+       err = arm_iommu_attach_device(dev, mtk_mapping);
+       if (err) {
+               iommu_group_remove_device(dev);
+               return err;
+       }
+
+       return iommu_device_link(&data->iommu, dev);;
 }
 
 static void mtk_iommu_remove_device(struct device *dev)
@@ -477,24 +484,6 @@ static void mtk_iommu_remove_device(struct device *dev)
        iommu_fwspec_free(dev);
 }
 
-static struct iommu_group *mtk_iommu_device_group(struct device *dev)
-{
-       struct mtk_iommu_data *data = dev->iommu_fwspec->iommu_priv;
-
-       if (!data)
-               return ERR_PTR(-ENODEV);
-
-       /* All the client devices are in the same m4u iommu-group */
-       if (!data->m4u_group) {
-               data->m4u_group = iommu_group_alloc();
-               if (IS_ERR(data->m4u_group))
-                       dev_err(dev, "Failed to allocate M4U IOMMU group\n");
-       } else {
-               iommu_group_ref_get(data->m4u_group);
-       }
-       return data->m4u_group;
-}
-
 static int mtk_iommu_hw_init(const struct mtk_iommu_data *data)
 {
        u32 regval;
@@ -547,7 +536,6 @@ static struct iommu_ops mtk_iommu_ops = {
        .iova_to_phys   = mtk_iommu_iova_to_phys,
        .add_device     = mtk_iommu_add_device,
        .remove_device  = mtk_iommu_remove_device,
-       .device_group   = mtk_iommu_device_group,
        .pgsize_bitmap  = ~0UL << MT2701_IOMMU_PAGE_SHIFT,
 };