Re: [PATCH 2/2] soc: mediatek: devapc: add devapc-mt6873 driver

[Chun-Kuang Hu <chunkuang.hu@kernel.org>]

Hi, Neal:

Neal Liu <neal.liu@mediatek.com> 於 2020年6月9日 週二 下午6:25寫道：
>
> MT6873 bus frabric provides TrustZone security support and data
> protection to prevent slaves from being accessed by unexpected
> masters.
> The security violations are logged and sent to the processor for
> further analysis or countermeasures.
>
> Any occurrence of security violation would raise an interrupt, and
> it will be handled by devapc-mt6873 driver. The violation
> information is printed in order to find the murderer.
>
> Signed-off-by: Neal Liu <neal.liu@mediatek.com>

[snip]

> +
> +/*
> + * sramrom_vio_handler - clean sramrom violation & print violation information
> + *                      for debugging.
> + */
> +static void sramrom_vio_handler(void)
> +{
> +       const struct mtk_sramrom_sec_vio_desc *sramrom_vios;
> +       struct mtk_devapc_vio_info *vio_info;
> +       struct arm_smccc_res res;
> +       size_t sramrom_vio_sta;
> +       int sramrom_vio;
> +       u32 rw;
> +
> +       sramrom_vios = mtk_devapc_ctx->soc->sramrom_sec_vios;
> +       vio_info = mtk_devapc_ctx->soc->vio_info;
> +
> +       arm_smccc_smc(MTK_SIP_KERNEL_CLR_SRAMROM_VIO,
> +                     0, 0, 0, 0, 0, 0, 0, &res);
> +
> +       sramrom_vio = res.a0;
> +       sramrom_vio_sta = res.a1;
> +       vio_info->vio_addr = res.a2;
> +
> +       if (sramrom_vio == SRAM_VIOLATION)
> +               pr_info(PFX "%s, SRAM violation is triggered\n", __func__);
> +       else if (sramrom_vio == ROM_VIOLATION)
> +               pr_info(PFX "%s, ROM violation is triggered\n", __func__);
> +       else
> +               return;
> +
> +       vio_info->master_id = (sramrom_vio_sta & sramrom_vios->vio_id_mask)
> +                       >> sramrom_vios->vio_id_shift;
> +       vio_info->domain_id = (sramrom_vio_sta & sramrom_vios->vio_domain_mask)
> +                       >> sramrom_vios->vio_domain_shift;
> +       rw = (sramrom_vio_sta & sramrom_vios->vio_rw_mask) >>
> +                       sramrom_vios->vio_rw_shift;

I think some information, such as master_id, would be get in
devapc_extract_vio_dbg(), you need not to get it here.

> +
> +       if (rw)
> +               vio_info->write = 1;
> +       else
> +               vio_info->read = 1;
> +
> +       pr_info(PFX "%s: %s:0x%x, %s:0x%x, %s:%s, %s:0x%x\n",
> +               __func__, "master_id", vio_info->master_id,
> +               "domain_id", vio_info->domain_id,
> +               "rw", rw ? "Write" : "Read",
> +               "vio_addr", vio_info->vio_addr);
> +}
> +

[snip]

> +
> +/*
> + * devapc_violation_irq - the devapc Interrupt Service Routine (ISR) will dump
> + *                       violation information including which master violates
> + *                       access slave.
> + */
> +static irqreturn_t devapc_violation_irq(int irq_number, void *dev_id)
> +{
> +       u32 slave_type_num = mtk_devapc_ctx->soc->slave_type_num;

Don't make  mtk_devapc_ctx a global variable. You should allocate
instance of  mtk_devapc_ctx in probe(), and pass  mtk_devapc_ctx to
the last parameter of devm_request_irq(), and it would be the second
parameter of irq handler.

> +       const struct mtk_device_info **device_info;
> +       struct mtk_devapc_vio_info *vio_info;
> +       int slave_type, vio_idx, index;
> +       const char *vio_master;
> +       unsigned long flags;
> +       bool normal;
> +       u8 perm;
> +
> +       spin_lock_irqsave(&devapc_lock, flags);
> +
> +       device_info = mtk_devapc_ctx->soc->device_info;
> +       vio_info = mtk_devapc_ctx->soc->vio_info;
> +       normal = false;
> +       vio_idx = -1;
> +       index = -1;
> +
> +       /* There are multiple DEVAPC_PD */
> +       for (slave_type = 0; slave_type < slave_type_num; slave_type++) {
> +               if (!check_type2_vio_status(slave_type, &vio_idx, &index))
> +                       if (!mtk_devapc_dump_vio_dbg(slave_type, &vio_idx,
> +                                                    &index))
> +                               continue;
> +
> +               /* Ensure that violation info are written before
> +                * further operations
> +                */
> +               smp_mb();
> +               normal = true;
> +
> +               mask_module_irq(slave_type, vio_idx, true);
> +
> +               if (clear_vio_status(slave_type, vio_idx))
> +                       pr_warn(PFX "%s, %s:0x%x, %s:0x%x\n",
> +                               "clear vio status failed",
> +                               "slave_type", slave_type,
> +                               "vio_index", vio_idx);
> +
> +               perm = get_permission(slave_type, index, vio_info->domain_id);
> +
> +               vio_master = mtk_devapc_ctx->soc->master_get
> +                       (vio_info->master_id,
> +                        vio_info->vio_addr,
> +                        slave_type,
> +                        vio_info->shift_sta_bit,
> +                        vio_info->domain_id);
> +
> +               if (!vio_master) {
> +                       pr_warn(PFX "master_get failed\n");
> +                       vio_master = "UNKNOWN_MASTER";
> +               }
> +
> +               pr_info(PFX "%s - %s:0x%x, %s:0x%x, %s:0x%x, %s:0x%x\n",
> +                       "Violation", "slave_type", slave_type,
> +                       "sys_index",
> +                       device_info[slave_type][index].sys_index,
> +                       "ctrl_index",
> +                       device_info[slave_type][index].ctrl_index,
> +                       "vio_index",
> +                       device_info[slave_type][index].vio_index);
> +
> +               pr_info(PFX "%s %s %s %s\n",
> +                       "Violation - master:", vio_master,
> +                       "access violation slave:",
> +                       device_info[slave_type][index].device);
> +
> +               devapc_vio_reason(perm);
> +
> +               devapc_extra_handler(slave_type, vio_master, vio_idx,
> +                                    vio_info->vio_addr);
> +
> +               mask_module_irq(slave_type, vio_idx, false);
> +       }
> +
> +       if (normal) {
> +               spin_unlock_irqrestore(&devapc_lock, flags);
> +               return IRQ_HANDLED;
> +       }
> +
> +       spin_unlock_irqrestore(&devapc_lock, flags);
> +       return IRQ_HANDLED;
> +}
> +

[snip]

> +
> +int mtk_devapc_probe(struct platform_device *pdev, struct mtk_devapc_soc *soc)
> +{
> +       struct device_node *node = pdev->dev.of_node;
> +       u32 slave_type_num;
> +       int slave_type;
> +       int ret;
> +
> +       if (IS_ERR(node))
> +               return -ENODEV;
> +
> +       mtk_devapc_ctx->soc = soc;
> +       slave_type_num = mtk_devapc_ctx->soc->slave_type_num;
> +
> +       for (slave_type = 0; slave_type < slave_type_num; slave_type++) {
> +               mtk_devapc_ctx->devapc_pd_base[slave_type] =
> +                       of_iomap(node, slave_type);
> +               if (!mtk_devapc_ctx->devapc_pd_base[slave_type])
> +                       return -EINVAL;
> +       }
> +
> +       mtk_devapc_ctx->infracfg_base = of_iomap(node, slave_type_num + 1);
> +       if (!mtk_devapc_ctx->infracfg_base)
> +               return -EINVAL;
> +
> +       mtk_devapc_ctx->devapc_irq = irq_of_parse_and_map(node, 0);
> +       if (!mtk_devapc_ctx->devapc_irq)
> +               return -EINVAL;
> +
> +       /* CCF (Common Clock Framework) */
> +       mtk_devapc_ctx->devapc_infra_clk = devm_clk_get(&pdev->dev,
> +                                                       "devapc-infra-clock");
> +
> +       if (IS_ERR(mtk_devapc_ctx->devapc_infra_clk))
> +               return -EINVAL;
> +
> +       proc_create("devapc_dbg", 0664, NULL, &devapc_dbg_fops);
> +
> +       if (clk_prepare_enable(mtk_devapc_ctx->devapc_infra_clk))
> +               return -EINVAL;
> +
> +       start_devapc();
> +
> +       ret = devm_request_irq(&pdev->dev, mtk_devapc_ctx->devapc_irq,
> +                              (irq_handler_t)devapc_violation_irq,
> +                              IRQF_TRIGGER_NONE, "devapc", NULL);
> +       if (ret) {
> +               pr_err(PFX "request devapc irq failed, ret:%d\n", ret);
> +               return ret;
> +       }
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL_GPL(mtk_devapc_probe);

Why export probe function?

> +
> +int mtk_devapc_remove(struct platform_device *dev)
> +{
> +       clk_disable_unprepare(mtk_devapc_ctx->devapc_infra_clk);
> +       return 0;
> +}
> +EXPORT_SYMBOL_GPL(mtk_devapc_remove);

Ditto.

Regards,
Chun-Kuang.