[PATCH v4 3/4] memory: mtk-smi: Add enable IOMMU SMC command for MM master

[Yong Wu]

On Mon, 2022-08-01 at 10:18 +0800, Chengci.Xu wrote:
> For concerns about security, the register to enable/disable IOMMU of
> SMI LARB should only be configured in secure world. Thus, we add some
> SMC command for multimedia master to enable/disable MM IOMMU in ATF
> by
> setting the register of SMI LARB. This function is prepared for
> MT8188.
> 
> Signed-off-by: Chengci.Xu <chengci.xu at mediatek.com>
> ---
>  drivers/memory/mtk-smi.c                 | 19 +++++++++++++++++++
>  include/linux/soc/mediatek/mtk_sip_svc.h |  3 +++
>  include/soc/mediatek/smi.h               |  5 +++++
>  3 files changed, 27 insertions(+)
> 
> diff --git a/drivers/memory/mtk-smi.c b/drivers/memory/mtk-smi.c
> index 08c1668d47bf..28e1123f9d76 100644
> --- a/drivers/memory/mtk-smi.c
> +++ b/drivers/memory/mtk-smi.c
> @@ -3,6 +3,7 @@
>   * Copyright (c) 2015-2016 MediaTek Inc.
>   * Author: Yong Wu <yong.wu at mediatek.com>
>   */
> +#include <linux/arm-smccc.h>
>  #include <linux/clk.h>
>  #include <linux/component.h>
>  #include <linux/device.h>
> @@ -14,6 +15,7 @@
>  #include <linux/of_platform.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/soc/mediatek/mtk_sip_svc.h>
>  #include <soc/mediatek/smi.h>
>  #include <dt-bindings/memory/mt2701-larb-port.h>
>  #include <dt-bindings/memory/mtk-memory-port.h>
> @@ -89,6 +91,7 @@
>  #define MTK_SMI_FLAG_THRT_UPDATE	BIT(0)
>  #define MTK_SMI_FLAG_SW_FLAG		BIT(1)
>  #define MTK_SMI_FLAG_SLEEP_CTL		BIT(2)
> +#define MTK_SMI_FLAG_CFG_PORT_SEC_CTL	BIT(3)
>  #define MTK_SMI_CAPS(flags, _x)		(!!((flags) & (_x)))
>  
>  struct mtk_smi_reg_pair {
> @@ -238,6 +241,7 @@ static int
> mtk_smi_larb_config_port_gen2_general(struct device *dev)
>  	struct mtk_smi_larb *larb = dev_get_drvdata(dev);
>  	u32 reg, flags_general = larb->larb_gen->flags_general;
>  	const u8 *larbostd = larb->larb_gen->ostd ? larb->larb_gen-
> >ostd[larb->larbid] : NULL;
> +	struct arm_smccc_res res;
>  	int i;
>  
>  	if (BIT(larb->larbid) & larb->larb_gen-
> >larb_direct_to_common_mask)
> @@ -262,6 +266,21 @@ static int
> mtk_smi_larb_config_port_gen2_general(struct device *dev)
>  		reg |= BANK_SEL(larb->bank[i]);
>  		writel(reg, larb->base + SMI_LARB_NONSEC_CON(i));
>  	}
> +
> +	/*
> +	 * We still need to write above NONSEC_CON register for bank
> selection
> +	 * even if enabling IOMMU is failed by SMC call. Otherwise, all
> master
> +	 * will be configured to bank 0 with a state of IOMMU enable
> due to the
> +	 * HW default value of register.

I don't understand this. Does bankX(X!=0) make sense if SMC fail? 

I guess the below segment should be before SMI_LARB_NONSEC_CON. It
means we shouldn't touch bank_sel while SMC fail.

Just add a comment like:
/* When mmu_en bits are in security world, the bank_sel still is in the
LARB_NONSEC_CON below. and the mmu_en of LARB_NONSEC_CON have no effect
in this case. */

> +	 */
> +	if (MTK_SMI_CAPS(flags_general, MTK_SMI_FLAG_CFG_PORT_SEC_CTL))
> {
> +		arm_smccc_smc(MTK_SIP_KERNEL_IOMMU_CONTROL,
> IOMMU_ATF_CMD_CONFIG_SMI_LARB,
> +			      larb->larbid, (u32)(*larb->mmu), 0, 0, 0,

The type of mmu is "u32", no need the "(u32)".

> 0, &res);
> +		if (res.a0 != 0) {
> +			dev_err(dev, "Enable iommu fail, ret %ld\n",
> res.a0);
> +			return -EINVAL;
> +		}
> +	}
>  	return 0;
>  }
>  
> diff --git a/include/linux/soc/mediatek/mtk_sip_svc.h
> b/include/linux/soc/mediatek/mtk_sip_svc.h
> index 082398e0cfb1..0761128b4354 100644
> --- a/include/linux/soc/mediatek/mtk_sip_svc.h
> +++ b/include/linux/soc/mediatek/mtk_sip_svc.h
> @@ -22,4 +22,7 @@
>  	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL, MTK_SIP_SMC_CONVENTION,
> \
>  			   ARM_SMCCC_OWNER_SIP, fn_id)
>  
> +/* IOMMU related SMC call */
> +#define MTK_SIP_KERNEL_IOMMU_CONTROL	MTK_SIP_SMC_CMD(0x514)
> +
>  #endif
> diff --git a/include/soc/mediatek/smi.h b/include/soc/mediatek/smi.h
> index 11f7d6b59642..dfd8efca5e60 100644
> --- a/include/soc/mediatek/smi.h
> +++ b/include/soc/mediatek/smi.h
> @@ -11,6 +11,11 @@
>  
>  #if IS_ENABLED(CONFIG_MTK_SMI)
>  
> +enum iommu_atf_cmd {
> +	IOMMU_ATF_CMD_CONFIG_SMI_LARB,		/* For mm master to
> en/disable iommu */
> +	IOMMU_ATF_CMD_MAX,
> +};
> +
>  #define MTK_SMI_MMU_EN(port)	BIT(port)
>  
>  struct mtk_smi_larb_iommu {