On 02/07/2020 11:37, Miles Chen wrote:
In previous disscusion [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 unexported symbol max_pfn.
[1] https://lkml.org/lkml/2020/6/3/733
[2] https://lkml.org/lkml/2020/6/4/136
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>
Signed-off-by: Miles Chen <miles.chen@xxxxxxxxxxxx>
---
drivers/iommu/mtk_iommu.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)
diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index 2be96f1cdbd2..09be57bd8d74 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>
@@ -15,11 +14,13 @@
#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 <asm/barrier.h>
@@ -91,6 +92,9 @@
#define F_MMU_INT_ID_LARB_ID(a) (((a) >> 7) & 0x7)
#define F_MMU_INT_ID_PORT_ID(a) (((a) >> 2) & 0x1f)
+#define REG_INFRA_MISC 0xf00
+#define F_DDR_4GB_SUPPORT_EN BIT(13)
+
As this is used for infracfg, I think it would be good to add it to
include/linux/soc/mediatek/infracfg.h and include that file here.
#define MTK_PROTECT_PA_ALIGN 128
/*
@@ -599,8 +603,10 @@ static int mtk_iommu_probe(struct platform_device *pdev)
struct resource *res;
resource_size_t ioaddr;
struct component_match *match = NULL;
+ struct regmap *infracfg_regmap;
Maybe call it just infracfg.
void *protect;
int i, larb_nr, ret;
+ u32 val;
data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
if (!data)
@@ -614,10 +620,18 @@ 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)
+ if (data->plat_data->has_4gb_mode) {
+ infracfg_regmap = syscon_regmap_lookup_by_phandle(dev->of_node,
+ "mediatek,infracfg");
+ if (IS_ERR(infracfg_regmap))
+ return PTR_ERR(infracfg_regmap);
Do we need to error out, or could we be conservative and set endable_4GB = false?
+ ret = regmap_read(infracfg_regmap, REG_INFRA_MISC, &val);
+ if (ret)
+ return ret;
+ data->enable_4GB = !!(val & F_DDR_4GB_SUPPORT_EN);
+ } else {
data->enable_4GB = false;
Move that before the if() and update enable_4GB only in case of has_4gb_mode.
+ }
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
data->base = devm_ioremap_resource(dev, res);
