Re: [PATCH 11/21] iommu/mediatek: Add power-domain operation

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

On Sat, 2020-07-11 at 14:48 +0800, Yong Wu wrote:
> In the previous SoC, the M4U HW is in the EMI power domain which is
> always on. the latest M4U is in the display power domain which may be
> turned on/off, thus we have to add pm_runtime interface for it.
> 
> we should enable its power before M4U hw initial. and disable it after HW
> initialize.
> 
> When the engine work, the engine always enable the power and clocks for
> smi-larb/smi-common, then the M4U's power will always be powered on
> automatically via the device link with smi-common.
> 
> Note: we don't enable the M4U power in iommu_map/unmap for tlb flush.
> If its power already is on, of course it is ok. if the power is off,
> the main tlb will be reset while M4U power on, thus the tlb flush while
> m4u power off is unnecessary, just skip it.
> 
> Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> ---
>  drivers/iommu/mtk_iommu.c | 54 ++++++++++++++++++++++++++++++++++-----
>  1 file changed, 47 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 931fdd19c8f3..03a6d66f4bef 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -20,6 +20,7 @@
>  #include <linux/of_irq.h>
>  #include <linux/of_platform.h>
>  #include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
>  #include <linux/slab.h>
>  #include <linux/spinlock.h>
>  #include <asm/barrier.h>
> @@ -172,6 +173,19 @@ static struct mtk_iommu_domain *to_mtk_domain(struct iommu_domain *dom)
>  	return container_of(dom, struct mtk_iommu_domain, domain);
>  }
>  
> +static int mtk_iommu_rpm_get(struct device *dev)
> +{
> +	if (pm_runtime_enabled(dev))
> +		return pm_runtime_get_sync(dev);
> +	return 0;
> +}
> +
> +static void mtk_iommu_rpm_put(struct device *dev)
> +{
> +	if (pm_runtime_enabled(dev))
> +		pm_runtime_put_autosuspend(dev);
> +}
> +
>  static void mtk_iommu_tlb_flush_all(void *cookie)
>  {
>  	struct mtk_iommu_data *data = cookie;
> @@ -193,6 +207,11 @@ static void mtk_iommu_tlb_flush_range_sync(unsigned long iova, size_t size,
>  	u32 tmp;
>  
>  	for_each_m4u(data) {
> +		/* skip tlb flush when pm is not active */
> +		if (pm_runtime_enabled(data->dev) &&
> +		    !pm_runtime_active(data->dev))
> +			continue;
> +
>  		spin_lock_irqsave(&data->tlb_lock, flags);
>  		writel_relaxed(F_INVLD_EN1 | F_INVLD_EN0,
>  			       data->base + data->plat_data->inv_sel_reg);
> @@ -377,15 +396,20 @@ static int mtk_iommu_attach_device(struct iommu_domain *domain,
>  {
>  	struct mtk_iommu_data *data = dev_iommu_priv_get(dev);
>  	struct mtk_iommu_domain *dom = to_mtk_domain(domain);
> +	int ret;
>  
>  	if (!data)
>  		return -ENODEV;
>  
>  	/* Update the pgtable base address register of the M4U HW */
>  	if (!data->m4u_dom) {
> +		ret = mtk_iommu_rpm_get(dev);
> +		if (ret < 0)
> +			return ret;
>  		data->m4u_dom = dom;
>  		writel(dom->cfg.arm_v7s_cfg.ttbr & MMU_PT_ADDR_MASK,
>  		       data->base + REG_MMU_PT_BASE_ADDR);
> +		mtk_iommu_rpm_put(dev);
>  	}
>  
>  	mtk_iommu_config(data, dev, true);
> @@ -543,10 +567,14 @@ static int mtk_iommu_hw_init(const struct mtk_iommu_data *data)
>  	u32 regval;
>  	int ret;
>  
> -	ret = clk_prepare_enable(data->bclk);
> -	if (ret) {
> -		dev_err(data->dev, "Failed to enable iommu bclk(%d)\n", ret);
> -		return ret;
> +	/* bclk will be enabled in pm callback in power-domain case. */
> +	if (!pm_runtime_enabled(data->dev)) {
> +		ret = clk_prepare_enable(data->bclk);
> +		if (ret) {
> +			dev_err(data->dev, "Failed to enable iommu bclk(%d)\n",
> +				ret);
> +			return ret;
> +		}
>  	}
>  
>  	if (data->plat_data->m4u_plat == M4U_MT8173) {
> @@ -728,7 +756,15 @@ static int mtk_iommu_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, data);
>  
> +	if (dev->pm_domain)
> +		pm_runtime_enable(dev);

hi yong,

If you put "pm_runtime_enable" here, it maybe not device_link with
smi_common for previous patch: 
if(i || !pm_runtime_enabled(dev))
    continue;

Whether put it up front?

best regards,
chao

> +
> +	ret = mtk_iommu_rpm_get(dev);
> +	if (ret < 0)
> +		return ret;
> +
>  	ret = mtk_iommu_hw_init(data);
> +	mtk_iommu_rpm_put(dev);
>  	if (ret)
>  		return ret;
>  
> @@ -801,6 +837,10 @@ 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;
>  	}
> +
> +	/* Avoid first resume to affect the default value of registers below. */
> +	if (!m4u_dom)
> +		return 0;
>  	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);
> @@ -809,13 +849,13 @@ static int __maybe_unused mtk_iommu_resume(struct device *dev)
>  	writel_relaxed(reg->int_main_control, base + REG_MMU_INT_MAIN_CONTROL);
>  	writel_relaxed(reg->ivrp_paddr, base + REG_MMU_IVRP_PADDR);
>  	writel_relaxed(reg->vld_pa_rng, base + REG_MMU_VLD_PA_RNG);
> -	if (m4u_dom)
> -		writel(m4u_dom->cfg.arm_v7s_cfg.ttbr & MMU_PT_ADDR_MASK,
> -		       base + REG_MMU_PT_BASE_ADDR);
> +	writel(m4u_dom->cfg.arm_v7s_cfg.ttbr & MMU_PT_ADDR_MASK,
> +	       base + REG_MMU_PT_BASE_ADDR);
>  	return 0;
>  }
>  
>  static const struct dev_pm_ops mtk_iommu_pm_ops = {
> +	SET_RUNTIME_PM_OPS(mtk_iommu_suspend, mtk_iommu_resume, NULL)
>  	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(mtk_iommu_suspend, mtk_iommu_resume)
>  };
>  

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