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

[chao hao <Chao.Hao@mediatek.com>]

Hi Matthias and Yingjoe,
Thanks for your comments!

On Mon, 2020-07-06 at 17:17 +0200, Matthias Brugger wrote:
> 
> On 04/07/2020 03:16, Yingjoe Chen wrote:
> > 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@mediatek.com>
> >> Suggested-by: Matthias Brugger <matthias.bgg@gmail.com>
> >> Signed-off-by: Chao Hao <chao.hao@mediatek.com>
> >> Reviewed-by: Matthias Brugger <matthias.bgg@gmail.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.
> > 
> 
> Actually I proposed to use the flag approach because I didn't want to bloat the
> mtk_iommu_plat_data structure with new variables for every new feature, being it
> a bit field or a bool.
> Regards,
> Matthias

@Yingjoe,
If you don't have other concerns, we will use Matthias's proposal,
thanks

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