linux-kernel - [PATCH 4/4] iommu/exynos: Add minimal support for SysMMU v7 with VM registers

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Date:   Sun,  3 Jul 2022 00:37:24 +0300
From:   Sam Protsenko <semen.protsenko@...aro.org>
To:     Marek Szyprowski <m.szyprowski@...sung.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Janghyuck Kim <janghyuck.kim@...sung.com>,
        Cho KyongHo <pullip.cho@...sung.com>,
        Daniel Mentz <danielmentz@...gle.com>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        iommu@...ts.linux-foundation.org, iommu@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 4/4] iommu/exynos: Add minimal support for SysMMU v7 with VM registers

Add minimal viable support for SysMMU v7.x, which can be found in modern
Exynos chips (like Exynos850). SysMMU v7.x may implement VM register
set, and those registers should be initialized properly if present.
Usually 8 translation domains are supported via VM registers (0..7), but
only n=0 (default) is used for now.

Changes are as follows:
  - add enabling the default VID instance before enabling SysMMU
  - use v7 VM register for setting the page table base address
  - use v7 VM register for invalidation

Insights for those changes were taken by comparing the I/O dump
(writel() / readl() operations) for vendor driver and this upstream
driver.

It was tested on E850-96 board, which has SysMMU v7.4 with VM registers
present. The testing was done using "Emulated Translation" registers.
That allows initiating translations with no actual users of that IOMMU,
and checking the result by reading the TLB info from corresponding
registers.

Thanks to Marek, who did let me know it only takes a slight change of
registers to make this driver work with v7.

Signed-off-by: Sam Protsenko <semen.protsenko@...aro.org>
---
 drivers/iommu/exynos-iommu.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
index 47017e8945c5..b7b4833161bc 100644
--- a/drivers/iommu/exynos-iommu.c
+++ b/drivers/iommu/exynos-iommu.c
@@ -135,6 +135,8 @@ static u32 lv2ent_offset(sysmmu_iova_t iova)
 #define CFG_SYSSEL	(1 << 22) /* System MMU 3.2 only */
 #define CFG_FLPDCACHE	(1 << 20) /* System MMU 3.2+ only */
 
+#define CTRL_VM_ENABLE			BIT(0)
+#define CTRL_VM_FAULT_MODE_STALL	BIT(3)
 #define CAPA0_CAPA1_EXIST		BIT(11)
 #define CAPA1_VCR_ENABLED		BIT(14)
 
@@ -358,8 +360,10 @@ static void __sysmmu_tlb_invalidate(struct sysmmu_drvdata *data)
 {
 	if (MMU_MAJ_VER(data->version) < 5)
 		writel(0x1, data->sfrbase + REG_MMU_FLUSH);
-	else
+	else if (MMU_MAJ_VER(data->version) < 7)
 		writel(0x1, data->sfrbase + REG_V5_MMU_FLUSH_ALL);
+	else
+		writel(0x1, MMU_VM_REG(data, IDX_ALL_INV, 0));
 }
 
 static void __sysmmu_tlb_invalidate_entry(struct sysmmu_drvdata *data,
@@ -391,9 +395,11 @@ static void __sysmmu_set_ptbase(struct sysmmu_drvdata *data, phys_addr_t pgd)
 {
 	if (MMU_MAJ_VER(data->version) < 5)
 		writel(pgd, data->sfrbase + REG_PT_BASE_ADDR);
-	else
+	else if (MMU_MAJ_VER(data->version) < 7)
 		writel(pgd >> PAGE_SHIFT,
 			     data->sfrbase + REG_V5_PT_BASE_PFN);
+	else
+		writel(pgd >> SPAGE_ORDER, MMU_VM_REG(data, IDX_FLPT_BASE, 0));
 
 	__sysmmu_tlb_invalidate(data);
 }
@@ -571,6 +577,12 @@ static void __sysmmu_enable(struct sysmmu_drvdata *data)
 	writel(CTRL_BLOCK, data->sfrbase + REG_MMU_CTRL);
 	__sysmmu_init_config(data);
 	__sysmmu_set_ptbase(data, data->pgtable);
+	if (MMU_MAJ_VER(data->version) >= 7 && data->has_vcr) {
+		u32 ctrl = readl(MMU_VM_REG(data, IDX_CTRL_VM, 0));
+
+		ctrl |= CTRL_VM_ENABLE | CTRL_VM_FAULT_MODE_STALL;
+		writel(ctrl, MMU_VM_REG(data, IDX_CTRL_VM, 0));
+	}
 	writel(CTRL_ENABLE, data->sfrbase + REG_MMU_CTRL);
 	data->active = true;
 	spin_unlock_irqrestore(&data->lock, flags);
-- 
2.30.2