From 539e70084bc2d9e4848cf7c3920a2145a44a67bb Mon Sep 17 00:00:00 2001
From: Simon Xue <xxm@rock-chips.com>
Date: Wed, 25 Oct 2017 17:10:04 +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 | 45 ++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c
index 9ac9829d00a9..5c42b2a08aaf 100644
--- a/drivers/iommu/rockchip-iommu.c
+++ b/drivers/iommu/rockchip-iommu.c
@@ -96,6 +96,7 @@ struct rk_iommu {
 	int *irq;
 	int num_irq;
 	bool reset_disabled; /* isp iommu reset operation would failed */
+	bool skip_read;	     /* rk3126/rk3128 can't read vop iommu registers */
 	struct list_head node; /* entry in rk_iommu_domain.iommus */
 	struct iommu_domain *domain; /* domain to which iommu is attached */
 	struct clk *aclk; /* aclock belong to master */
@@ -371,6 +372,9 @@ static int rk_iommu_enable_stall(struct rk_iommu *iommu)
 {
 	int ret, i;
 
+	if (iommu->skip_read)
+		goto read_wa;
+
 	if (rk_iommu_is_stall_active(iommu))
 		return 0;
 
@@ -378,7 +382,10 @@ 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 = rk_wait_for(rk_iommu_is_stall_active(iommu), 1);
 	if (ret)
@@ -393,10 +400,16 @@ static int rk_iommu_disable_stall(struct rk_iommu *iommu)
 {
 	int ret, i;
 
+	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 = rk_wait_for(!rk_iommu_is_stall_active(iommu), 1);
 	if (ret)
@@ -411,10 +424,16 @@ static int rk_iommu_enable_paging(struct rk_iommu *iommu)
 {
 	int ret, i;
 
+	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 = rk_wait_for(rk_iommu_is_paging_enabled(iommu), 1);
 	if (ret)
@@ -429,10 +448,16 @@ static int rk_iommu_disable_paging(struct rk_iommu *iommu)
 {
 	int ret, i;
 
+	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 = rk_wait_for(!rk_iommu_is_paging_enabled(iommu), 1);
 	if (ret)
@@ -452,6 +477,8 @@ 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.
@@ -466,7 +493,10 @@ 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;
 
 	for (i = 0; i < iommu->num_mmu; i++) {
 		ret = rk_wait_for(rk_iommu_read(iommu->bases[i], RK_MMU_DTE_ADDR) == 0x00000000,
@@ -865,6 +895,9 @@ static int rk_iommu_attach_device(struct iommu_domain *domain,
 
 	iommu->domain = domain;
 
+	if (iommu->skip_read)
+		goto skip_request_irq;
+
 	for (i = 0; i < iommu->num_irq; i++) {
 		ret = devm_request_irq(iommu->dev, iommu->irq[i], rk_iommu_irq,
 			       IRQF_SHARED, dev_name(dev), iommu);
@@ -872,6 +905,7 @@ static int rk_iommu_attach_device(struct iommu_domain *domain,
 			return ret;
 	}
 
+skip_request_irq:
 	for (i = 0; i < iommu->num_mmu; i++) {
 		rk_iommu_write(iommu->bases[i], RK_MMU_DTE_ADDR,
 			       rk_domain->dt_dma);
@@ -919,10 +953,14 @@ static void rk_iommu_detach_device(struct iommu_domain *domain,
 	}
 	rk_iommu_disable_stall(iommu);
 
+	if (iommu->skip_read)
+		goto read_wa;
+
 	for (i = 0; i < iommu->num_irq; i++) {
 		devm_free_irq(iommu->dev, iommu->irq[i], iommu);
 	}
 
+read_wa:
 	iommu->domain = NULL;
 
 	rk_iommu_power_off(iommu);
@@ -1210,6 +1248,13 @@ static int rk_iommu_probe(struct platform_device *pdev)
 	iommu->reset_disabled = device_property_read_bool(dev,
 				"rk_iommu,disable_reset_quirk");
 
+	/* Follow upstream */
+	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->aclk = devm_clk_get(dev, "aclk");
 	if (IS_ERR(iommu->aclk)) {
 		dev_info(dev, "can't get aclk\n");