linux-kernel - Re: [PATCH v6 03/10] iommu/mediatek: Use a u32 flags to describe different HW features

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Date:   Sat, 4 Jul 2020 09:16:38 +0800
From:   Yingjoe Chen <yingjoe.chen@...iatek.com>
To:     Chao Hao <chao.hao@...iatek.com>
CC:     Joerg Roedel <joro@...tes.org>, Rob Herring <robh+dt@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        <devicetree@...r.kernel.org>, "FY Yang" <fy.yang@...iatek.com>,
        <wsd_upstream@...iatek.com>, <linux-kernel@...r.kernel.org>,
        <iommu@...ts.linux-foundation.org>, TH Yang <th.yang@...iatek.com>,
        <linux-mediatek@...ts.infradead.org>,
        Yong Wu <yong.wu@...iatek.com>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v6 03/10] iommu/mediatek: Use a u32 flags to describe
 different HW features

On Fri, 2020-07-03 at 12:41 +0800, Chao Hao wrote:
> Given the fact that we are adding more and more plat_data bool values,
> it would make sense to use a u32 flags register and add the appropriate
> macro definitions to set and check for a flag present.
> No functional change.
> 
> Cc: Yong Wu <yong.wu@...iatek.com>
> Suggested-by: Matthias Brugger <matthias.bgg@...il.com>
> Signed-off-by: Chao Hao <chao.hao@...iatek.com>
> Reviewed-by: Matthias Brugger <matthias.bgg@...il.com>
> ---
>  drivers/iommu/mtk_iommu.c | 28 +++++++++++++++++-----------
>  drivers/iommu/mtk_iommu.h |  7 +------
>  2 files changed, 18 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 88d3df5b91c2..40ca564d97af 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -100,6 +100,15 @@
>  #define MTK_M4U_TO_LARB(id)		(((id) >> 5) & 0xf)
>  #define MTK_M4U_TO_PORT(id)		((id) & 0x1f)
>  
> +#define HAS_4GB_MODE			BIT(0)
> +/* HW will use the EMI clock if there isn't the "bclk". */
> +#define HAS_BCLK			BIT(1)
> +#define HAS_VLD_PA_RNG			BIT(2)
> +#define RESET_AXI			BIT(3)
> +
> +#define MTK_IOMMU_HAS_FLAG(pdata, _x) \
> +		((((pdata)->flags) & (_x)) == (_x))
> +
>  struct mtk_iommu_domain {
>  	struct io_pgtable_cfg		cfg;
>  	struct io_pgtable_ops		*iop;
> @@ -563,7 +572,8 @@ static int mtk_iommu_hw_init(const struct mtk_iommu_data *data)
>  			 upper_32_bits(data->protect_base);
>  	writel_relaxed(regval, data->base + REG_MMU_IVRP_PADDR);
>  
> -	if (data->enable_4GB && data->plat_data->has_vld_pa_rng) {
> +	if (data->enable_4GB &&
> +	    MTK_IOMMU_HAS_FLAG(data->plat_data, HAS_VLD_PA_RNG)) {
>  		/*
>  		 * If 4GB mode is enabled, the validate PA range is from
>  		 * 0x1_0000_0000 to 0x1_ffff_ffff. here record bit[32:30].
> @@ -573,7 +583,7 @@ static int mtk_iommu_hw_init(const struct mtk_iommu_data *data)
>  	}
>  	writel_relaxed(0, data->base + REG_MMU_DCM_DIS);
>  
> -	if (data->plat_data->reset_axi) {
> +	if (MTK_IOMMU_HAS_FLAG(data->plat_data, RESET_AXI)) {
>  		/* The register is called STANDARD_AXI_MODE in this case */
>  		writel_relaxed(0, data->base + REG_MMU_MISC_CTRL);
>  	}
> @@ -618,7 +628,7 @@ static int mtk_iommu_probe(struct platform_device *pdev)
>  
>  	/* 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 (!MTK_IOMMU_HAS_FLAG(data->plat_data, HAS_4GB_MODE))
>  		data->enable_4GB = false;
>  
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> @@ -631,7 +641,7 @@ static int mtk_iommu_probe(struct platform_device *pdev)
>  	if (data->irq < 0)
>  		return data->irq;
>  
> -	if (data->plat_data->has_bclk) {
> +	if (MTK_IOMMU_HAS_FLAG(data->plat_data, HAS_BCLK)) {
>  		data->bclk = devm_clk_get(dev, "bclk");
>  		if (IS_ERR(data->bclk))
>  			return PTR_ERR(data->bclk);
> @@ -763,23 +773,19 @@ static const struct dev_pm_ops mtk_iommu_pm_ops = {
>  
>  static const struct mtk_iommu_plat_data mt2712_data = {
>  	.m4u_plat     = M4U_MT2712,
> -	.has_4gb_mode = true,
> -	.has_bclk     = true,
> -	.has_vld_pa_rng   = true,
> +	.flags        = HAS_4GB_MODE | HAS_BCLK | HAS_VLD_PA_RNG,
>  	.larbid_remap = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9},
>  };
>  
>  static const struct mtk_iommu_plat_data mt8173_data = {
>  	.m4u_plat     = M4U_MT8173,
> -	.has_4gb_mode = true,
> -	.has_bclk     = true,
> -	.reset_axi    = true,
> +	.flags	      = HAS_4GB_MODE | HAS_BCLK | RESET_AXI,
>  	.larbid_remap = {0, 1, 2, 3, 4, 5}, /* Linear mapping. */
>  };
>  
>  static const struct mtk_iommu_plat_data mt8183_data = {
>  	.m4u_plat     = M4U_MT8183,
> -	.reset_axi    = true,
> +	.flags        = RESET_AXI,
>  	.larbid_remap = {0, 4, 5, 6, 7, 2, 3, 1},
>  };
>  
> diff --git a/drivers/iommu/mtk_iommu.h b/drivers/iommu/mtk_iommu.h
> index 7212e6fcf982..5225a9170aaa 100644
> --- a/drivers/iommu/mtk_iommu.h
> +++ b/drivers/iommu/mtk_iommu.h
> @@ -39,12 +39,7 @@ enum mtk_iommu_plat {
>  
>  struct mtk_iommu_plat_data {
>  	enum mtk_iommu_plat m4u_plat;
> -	bool                has_4gb_mode;
> -
> -	/* HW will use the EMI clock if there isn't the "bclk". */
> -	bool                has_bclk;
> -	bool                has_vld_pa_rng;
> -	bool                reset_axi;
> +	u32                 flags;


How about using bit field instead? eg

  u32 has_bclk:1;

In this way, we don't need to change code.

Joe.C