iommu/mediatek: Add REG_MMU_WR_LEN_CTRL register definition

Some platforms(ex: mt6779) need to improve performance by setting
REG_MMU_WR_LEN_CTRL register. And we can use WR_THROT_EN macro to control
whether we need to set the register. If the register uses default value,
iommu will send command to EMI without restriction, when the number of
commands become more and more, it will drop the EMI performance. So when
more than ten_commands(default value) don't be handled for EMI, iommu will
stop send command to EMI for keeping EMI's performace by enabling write
throttling mechanism(bit[5][21]=0) in MMU_WR_LEN_CTRL register.

Signed-off-by: Chao Hao <[email protected]>
Reviewed-by: Matthias Brugger <[email protected]>
Cc: Matthias Brugger <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Joerg Roedel <[email protected]>

Author: Chao Hao

drivers/iommu/mtk_iommu.c

@@ -46,6 +46,8 @@
 #define F_MMU_STANDARD_AXI_MODE_MASK		(BIT(3) | BIT(19))
 
 #define REG_MMU_DCM_DIS				0x050
+#define REG_MMU_WR_LEN_CTRL			0x054
+#define F_MMU_WR_THROT_DIS_MASK			(BIT(5) | BIT(21))
 
 #define REG_MMU_CTRL_REG			0x110
 #define F_MMU_TF_PROT_TO_PROGRAM_ADDR		(2 << 4)
@@ -112,6 +114,7 @@
 #define RESET_AXI			BIT(3)
 #define OUT_ORDER_WR_EN			BIT(4)
 #define HAS_SUB_COMM			BIT(5)
+#define WR_THROT_EN			BIT(6)
 
 #define MTK_IOMMU_HAS_FLAG(pdata, _x) \
 		((((pdata)->flags) & (_x)) == (_x))
@@ -593,6 +596,12 @@ static int mtk_iommu_hw_init(const struct mtk_iommu_data *data)
 		writel_relaxed(regval, data->base + REG_MMU_VLD_PA_RNG);
 	}
 	writel_relaxed(0, data->base + REG_MMU_DCM_DIS);
+	if (MTK_IOMMU_HAS_FLAG(data->plat_data, WR_THROT_EN)) {
+		/* write command throttling mode */
+		regval = readl_relaxed(data->base + REG_MMU_WR_LEN_CTRL);
+		regval &= ~F_MMU_WR_THROT_DIS_MASK;
+		writel_relaxed(regval, data->base + REG_MMU_WR_LEN_CTRL);
+	}
 
 	if (MTK_IOMMU_HAS_FLAG(data->plat_data, RESET_AXI)) {
 		/* The register is called STANDARD_AXI_MODE in this case */
@@ -747,6 +756,7 @@ static int __maybe_unused mtk_iommu_suspend(struct device *dev)
 	struct mtk_iommu_suspend_reg *reg = &data->reg;
 	void __iomem *base = data->base;
 
+	reg->wr_len_ctrl = readl_relaxed(base + REG_MMU_WR_LEN_CTRL);
 	reg->misc_ctrl = readl_relaxed(base + REG_MMU_MISC_CTRL);
 	reg->dcm_dis = readl_relaxed(base + REG_MMU_DCM_DIS);
 	reg->ctrl_reg = readl_relaxed(base + REG_MMU_CTRL_REG);
@@ -771,6 +781,7 @@ static int __maybe_unused mtk_iommu_resume(struct device *dev)
 		dev_err(data->dev, "Failed to enable clk(%d) in resume\n", ret);
 		return ret;
 	}
+	writel_relaxed(reg->wr_len_ctrl, base + REG_MMU_WR_LEN_CTRL);
 	writel_relaxed(reg->misc_ctrl, base + REG_MMU_MISC_CTRL);
 	writel_relaxed(reg->dcm_dis, base + REG_MMU_DCM_DIS);
 	writel_relaxed(reg->ctrl_reg, base + REG_MMU_CTRL_REG);

drivers/iommu/mtk_iommu.h

@@ -31,6 +31,7 @@ struct mtk_iommu_suspend_reg {
 	u32				int_main_control;
 	u32				ivrp_paddr;
 	u32				vld_pa_rng;
+	u32				wr_len_ctrl;
 };
 
 enum mtk_iommu_plat {