Re: [PATCH v2] iommu/mediatek: check 4GB mode by reading infracfg
From: Matthias Brugger
Date: Tue Jul 21 2020 - 17:19:28 EST
On 21/07/2020 13:24, Yong Wu wrote:
On Tue, 2020-07-21 at 11:40 +0200, Matthias Brugger wrote:
On 21/07/2020 04:16, Miles Chen wrote:
In previous discussion [1] and [2], we found that it is risky to
use max_pfn or totalram_pages to tell if 4GB mode is enabled.
Check 4GB mode by reading infracfg register, remove the usage
of the un-exported symbol max_pfn.
This is a step towards building mtk_iommu as a kernel module.
Change since v1:
1. remove the phandle usage, search for infracfg instead [3]
2. use infracfg instead of infracfg_regmap
3. move infracfg definitaions to linux/soc/mediatek/infracfg.h
4. update enable_4GB only when has_4gb_mode
[1] https://lkml.org/lkml/2020/6/3/733
[2] https://lkml.org/lkml/2020/6/4/136
[3] https://lkml.org/lkml/2020/7/15/1147
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Yong Wu <yong.wu@xxxxxxxxxxxx>
Cc: Yingjoe Chen <yingjoe.chen@xxxxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Yong Wu <yong.wu@xxxxxxxxxxxx>
Cc: Chao Hao <chao.hao@xxxxxxxxxxxx>
Cc: Rob Herring <robh@xxxxxxxxxx>
Cc: Matthias Brugger <matthias.bgg@xxxxxxxxx>
Signed-off-by: Miles Chen <miles.chen@xxxxxxxxxxxx>
---
drivers/iommu/mtk_iommu.c | 26 +++++++++++++++++++++-----
include/linux/soc/mediatek/infracfg.h | 3 +++
2 files changed, 24 insertions(+), 5 deletions(-)
diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index 2be96f1cdbd2..16765f532853 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -3,7 +3,6 @@
* Copyright (c) 2015-2016 MediaTek Inc.
* Author: Yong Wu <yong.wu@xxxxxxxxxxxx>
*/
-#include <linux/memblock.h>
#include <linux/bug.h>
#include <linux/clk.h>
#include <linux/component.h>
@@ -15,13 +14,16 @@
#include <linux/iommu.h>
#include <linux/iopoll.h>
#include <linux/list.h>
+#include <linux/mfd/syscon.h>
#include <linux/of_address.h>
#include <linux/of_iommu.h>
#include <linux/of_irq.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
+#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
+#include <linux/soc/mediatek/infracfg.h>
#include <asm/barrier.h>
#include <soc/mediatek/smi.h>
@@ -599,8 +601,10 @@ static int mtk_iommu_probe(struct platform_device *pdev)
struct resource *res;
resource_size_t ioaddr;
struct component_match *match = NULL;
+ struct regmap *infracfg;
void *protect;
int i, larb_nr, ret;
+ u32 val;
data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
if (!data)
@@ -614,10 +618,22 @@ static int mtk_iommu_probe(struct platform_device *pdev)
return -ENOMEM;
data->protect_base = ALIGN(virt_to_phys(protect), MTK_PROTECT_PA_ALIGN);
- /* Whether the current dram is over 4GB */
- data->enable_4GB = !!(max_pfn > (BIT_ULL(32) >> PAGE_SHIFT));
- if (!data->plat_data->has_4gb_mode)
- data->enable_4GB = false;
+ data->enable_4GB = false;
+ if (data->plat_data->has_4gb_mode) {
+ infracfg = syscon_regmap_lookup_by_compatible(
+ "mediatek,mt8173-infracfg");
+ if (IS_ERR(infracfg)) {
+ infracfg = syscon_regmap_lookup_by_compatible(
+ "mediatek,mt2712-infracfg");
+ if (IS_ERR(infracfg))
+ return PTR_ERR(infracfg);
I think we should check m4u_plat instead to decide which compatible we have to
look for.
Another option would be to add a general compatible something like
"mtk-infracfg" and search for that. That would need an update of all DTS having
a infracfg compatible right now. After thinking twice, this would break newer
kernel with older device tree, so maybe it's better to go with m4u_plat switch
statement.
Add a "char *infracfg" in the plat_data, Use the mt2712, mt8173
corresponding string in it. If it is NULL, It means the "enable_4GB"
always is false. Then we also can remove the flag "has_4gb_mode".
is this OK?
It's an option, but I personally find that a bit hacky.
Regards,
Matthias