From a1efc0f6e7d4fcd58c2e9c56a63cc5edd47e4284 Mon Sep 17 00:00:00 2001
From: Simon Xue <xxm@rock-chips.com>
Date: Tue, 6 Apr 2021 16:18:15 +0800
Subject: [PATCH] iommu/rockchip: skip read vop iommu registers on rk3128 and
 rk3126

RK3128 and RK3126 failed to read vop iommu register, it is SoC bug.
Add this patch as a workaround for this bug, make SoC work as normal

Change-Id: I44d4ef7f6e15f85a466563b0b3e8e091db23fba0
Signed-off-by: Simon Xue <xxm@rock-chips.com>
---
 drivers/iommu/rockchip-iommu.c | 37 ++++++++++++++++++++++++++++++++++
 1 file changed, 37 insertions(+)

diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
index e5d86b7177de..5d4b8955962c 100644
--- a/drivers/iommu/rockchip-iommu.c
+++ b/drivers/iommu/rockchip-iommu.c
@@ -104,6 +104,7 @@ struct rk_iommu {
 	struct clk_bulk_data *clocks;
 	int num_clocks;
 	bool reset_disabled;
+	bool skip_read; /* rk3126/rk3128 can't read vop iommu registers */
 	struct iommu_device iommu;
 	struct list_head node; /* entry in rk_iommu_domain.iommus */
 	struct iommu_domain *domain; /* domain to which iommu is attached */
@@ -351,6 +352,9 @@ static int rk_iommu_enable_stall(struct rk_iommu *iommu)
 	int ret, i;
 	bool val;
 
+	if (iommu->skip_read)
+		goto read_wa;
+
 	if (rk_iommu_is_stall_active(iommu))
 		return 0;
 
@@ -358,7 +362,10 @@ static int rk_iommu_enable_stall(struct rk_iommu *iommu)
 	if (!rk_iommu_is_paging_enabled(iommu))
 		return 0;
 
+read_wa:
 	rk_iommu_command(iommu, RK_MMU_CMD_ENABLE_STALL);
+	if (iommu->skip_read)
+		return 0;
 
 	ret = readx_poll_timeout(rk_iommu_is_stall_active, iommu, val,
 				 val, RK_MMU_POLL_PERIOD_US,
@@ -376,10 +383,16 @@ static int rk_iommu_disable_stall(struct rk_iommu *iommu)
 	int ret, i;
 	bool val;
 
+	if (iommu->skip_read)
+		goto read_wa;
+
 	if (!rk_iommu_is_stall_active(iommu))
 		return 0;
 
+read_wa:
 	rk_iommu_command(iommu, RK_MMU_CMD_DISABLE_STALL);
+	if (iommu->skip_read)
+		return 0;
 
 	ret = readx_poll_timeout(rk_iommu_is_stall_active, iommu, val,
 				 !val, RK_MMU_POLL_PERIOD_US,
@@ -397,10 +410,16 @@ static int rk_iommu_enable_paging(struct rk_iommu *iommu)
 	int ret, i;
 	bool val;
 
+	if (iommu->skip_read)
+		goto read_wa;
+
 	if (rk_iommu_is_paging_enabled(iommu))
 		return 0;
 
+read_wa:
 	rk_iommu_command(iommu, RK_MMU_CMD_ENABLE_PAGING);
+	if (iommu->skip_read)
+		return 0;
 
 	ret = readx_poll_timeout(rk_iommu_is_paging_enabled, iommu, val,
 				 val, RK_MMU_POLL_PERIOD_US,
@@ -418,10 +437,16 @@ static int rk_iommu_disable_paging(struct rk_iommu *iommu)
 	int ret, i;
 	bool val;
 
+	if (iommu->skip_read)
+		goto read_wa;
+
 	if (!rk_iommu_is_paging_enabled(iommu))
 		return 0;
 
+read_wa:
 	rk_iommu_command(iommu, RK_MMU_CMD_DISABLE_PAGING);
+	if (iommu->skip_read)
+		return 0;
 
 	ret = readx_poll_timeout(rk_iommu_is_paging_enabled, iommu, val,
 				 !val, RK_MMU_POLL_PERIOD_US,
@@ -443,6 +468,9 @@ static int rk_iommu_force_reset(struct rk_iommu *iommu)
 	if (iommu->reset_disabled)
 		return 0;
 
+	if (iommu->skip_read)
+		goto read_wa;
+
 	/*
 	 * Check if register DTE_ADDR is working by writing DTE_ADDR_DUMMY
 	 * and verifying that upper 5 nybbles are read back.
@@ -457,7 +485,10 @@ static int rk_iommu_force_reset(struct rk_iommu *iommu)
 		}
 	}
 
+read_wa:
 	rk_iommu_command(iommu, RK_MMU_CMD_FORCE_RESET);
+	if (iommu->skip_read)
+		return 0;
 
 	ret = readx_poll_timeout(rk_iommu_is_reset_done, iommu, val,
 				 val, RK_MMU_FORCE_RESET_TIMEOUT_US,
@@ -1161,6 +1192,8 @@ static int rk_iommu_probe(struct platform_device *pdev)
 
 	iommu->reset_disabled = device_property_read_bool(dev,
 					"rockchip,disable-mmu-reset");
+	iommu->skip_read = device_property_read_bool(dev,
+					"rockchip,skip-mmu-read");
 
 	iommu->num_clocks = ARRAY_SIZE(rk_iommu_clocks);
 	iommu->clocks = devm_kcalloc(iommu->dev, iommu->num_clocks,
@@ -1215,6 +1248,9 @@ static int rk_iommu_probe(struct platform_device *pdev)
 
 	pm_runtime_enable(dev);
 
+	if (iommu->skip_read)
+		goto skip_request_irq;
+
 	for (i = 0; i < iommu->num_irq; i++) {
 		int irq = platform_get_irq(pdev, i);
 
@@ -1229,6 +1265,7 @@ static int rk_iommu_probe(struct platform_device *pdev)
 		}
 	}
 
+skip_request_irq:
 	return 0;
 err_remove_sysfs:
 	iommu_device_sysfs_remove(&iommu->iommu);