Re: [PATCH v6 31/34] iommu/mediatek: Get the proper bankid for multi banks

[Matthias Brugger <matthias.bgg@gmail.com>]

On 07/04/2022 09:57, Yong Wu wrote:
> We preassign some ports in a special bank via the new defined
> banks_portmsk. Put it in the plat_data means it is not expected to be
> adjusted dynamically.
> 
> If the iommu id in the iommu consumer's dtsi node is inside this
> banks_portmsk, then we switch it to this special iommu bank, and
> initialise the IOMMU bank HW.
> 
> Each a bank has the independent pgtable(4GB iova range). Each a bank
> is a independent iommu domain/group. Currently we don't separate different
> iova ranges inside a bank.
> 
> Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> ---
>   drivers/iommu/mtk_iommu.c | 39 ++++++++++++++++++++++++++++++++++++---
>   1 file changed, 36 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 0828cff97625..d42b3d35a36e 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -191,6 +191,7 @@ struct mtk_iommu_plat_data {
>   
>   	u8                  banks_num;
>   	bool                banks_enable[MTK_IOMMU_BANK_MAX];
> +	unsigned int        banks_portmsk[MTK_IOMMU_BANK_MAX];
>   	unsigned char       larbid_remap[MTK_LARB_COM_MAX][MTK_LARB_SUBCOM_MAX];
>   };
>   
> @@ -467,6 +468,30 @@ static irqreturn_t mtk_iommu_isr(int irq, void *dev_id)
>   	return IRQ_HANDLED;
>   }
>   
> +static unsigned int mtk_iommu_get_bank_id(struct device *dev,
> +					  const struct mtk_iommu_plat_data *plat_data)
> +{
> +	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> +	unsigned int i, portmsk = 0, bankid = 0;
> +
> +	if (plat_data->banks_num == 1)
> +		return bankid;
> +
> +	for (i = 0; i < fwspec->num_ids; i++)
> +		portmsk |= BIT(MTK_M4U_TO_PORT(fwspec->ids[i]));
> +
> +	for (i = 0; i < plat_data->banks_num && i < MTK_IOMMU_BANK_MAX; i++) {
> +		if (!plat_data->banks_enable[i])
> +			continue;
> +
> +		if (portmsk & plat_data->banks_portmsk[i]) {
> +			bankid = i;
> +			break;
> +		}
> +	}
> +	return bankid; /* default is 0 */
> +}
> +
>   static int mtk_iommu_get_iova_region_id(struct device *dev,
>   					const struct mtk_iommu_plat_data *plat_data)
>   {
> @@ -619,13 +644,14 @@ static int mtk_iommu_attach_device(struct iommu_domain *domain,
>   	struct list_head *hw_list = data->hw_list;
>   	struct device *m4udev = data->dev;
>   	struct mtk_iommu_bank_data *bank;
> -	unsigned int bankid = 0;
> +	unsigned int bankid;
>   	int ret, region_id;
>   
>   	region_id = mtk_iommu_get_iova_region_id(dev, data->plat_data);
>   	if (region_id < 0)
>   		return region_id;
>   
> +	bankid = mtk_iommu_get_bank_id(dev, data->plat_data);
>   	mutex_lock(&dom->mutex);
>   	if (!dom->bank) {
>   		/* Data is in the frstdata in sharing pgtable case. */
> @@ -802,6 +828,7 @@ static struct iommu_group *mtk_iommu_device_group(struct device *dev)
>   	struct mtk_iommu_data *c_data = dev_iommu_priv_get(dev), *data;
>   	struct list_head *hw_list = c_data->hw_list;
>   	struct iommu_group *group;
> +	unsigned int bankid, groupid;
>   	int regionid;
>   
>   	data = mtk_iommu_get_frst_data(hw_list);
> @@ -812,12 +839,18 @@ static struct iommu_group *mtk_iommu_device_group(struct device *dev)
>   	if (regionid < 0)
>   		return ERR_PTR(regionid);
>   
> +	bankid = mtk_iommu_get_bank_id(dev, data->plat_data);

I think code readability would be improved if we add a new function like 
mtk_iommu_get_id which call mtk_iommu_get_bankid and if necessary 
mtk_iommu_get_regionid.

>   	mutex_lock(&data->mutex);
> -	group = data->m4u_group[regionid];
> +	/*
> +	 * If the bank function is enabled, each a bank is a iommu group/domain.
> +	 * otherwise, each a iova region is a iommu group/domain.

While at it:
"If the bank function is enabled, each bank is a iommu group/domain. Otherwise, 
each iova region is a iommu group/domain."

Regards,
Matthias

> +	 */
> +	groupid = bankid ? bankid : regionid;
> +	group = data->m4u_group[groupid];
>   	if (!group) {
>   		group = iommu_group_alloc();
>   		if (!IS_ERR(group))
> -			data->m4u_group[regionid] = group;
> +			data->m4u_group[groupid] = group;
>   	} else {
>   		iommu_group_ref_get(group);
>   	}