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Message-ID: <755c5428-da97-416c-9af3-52b94cbe4ac5@kernel.org>
Date: Mon, 26 Aug 2024 20:45:38 +0200
From: Krzysztof Kozlowski <krzk@...nel.org>
To: Jan Kiszka <jan.kiszka@...mens.com>, Nishanth Menon <nm@...com>,
Santosh Shilimkar <ssantosh@...nel.org>,
Vignesh Raghavendra <vigneshr@...com>, Rob Herring <robh+dt@...nel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
Conor Dooley <conor+dt@...nel.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
devicetree@...r.kernel.org, Siddharth Vadapalli <s-vadapalli@...com>,
Bao Cheng Su <baocheng.su@...mens.com>, Hua Qian Li
<huaqian.li@...mens.com>, Diogo Ivo <diogo.ivo@...mens.com>
Subject: Re: [PATCH 2/5] soc: ti: Add IOMPU-like PVU driver
On 26/08/2024 19:56, Jan Kiszka wrote:
> From: Jan Kiszka <jan.kiszka@...mens.com>
>
> The TI Peripheral Virtualization Unit (PVU) permits to define a limited
> set of mappings for DMA requests on the system memory. Unlike with an
> IOMMU, there is no fallback to a memory-backed page table, only a fixed
> set of register-backed TLBs. Emulating an IOMMU behavior appears to be
> the more fragile the more fragmentation of pending requests occur.
>
> Therefore, this driver does not expose the PVU as an IOMMU. It rather
> introduces a simple, static interface to devices that are under
> restricted-dma-pool constraints. They can register their pools with the
> PVUs, enabling only those pools to work for DMA. As also MSI is issued
> as DMA, the PVU already register the related translator region of the
> AM654 as valid DMA target.
>
> This driver is the essential building block for limiting DMA from
> untrusted devices to clearly defined memory regions in the absence of a
> real IOMMU (SMMU).
>
> Co-developed-by: Diogo Ivo <diogo.ivo@...mens.com>
> Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
> ---
> drivers/soc/ti/Kconfig | 4 +
> drivers/soc/ti/Makefile | 1 +
> drivers/soc/ti/ti-pvu.c | 487 ++++++++++++++++++++++++++++++++++++++++
> include/linux/ti-pvu.h | 11 +
> 4 files changed, 503 insertions(+)
> create mode 100644 drivers/soc/ti/ti-pvu.c
> create mode 100644 include/linux/ti-pvu.h
>
> diff --git a/drivers/soc/ti/Kconfig b/drivers/soc/ti/Kconfig
> index 1a93001c9e36..af7173ad84de 100644
> --- a/drivers/soc/ti/Kconfig
> +++ b/drivers/soc/ti/Kconfig
> @@ -82,6 +82,10 @@ config TI_PRUSS
> processors on various TI SoCs. It's safe to say N here if you're
> not interested in the PRU or if you are unsure.
>
...
> +
> +static int ti_pvu_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct device_node *its_node;
> + void __iomem *base;
> + struct ti_pvu *pvu;
> + u32 val;
> + int ret;
> +
> + pvu = devm_kzalloc(dev, sizeof(struct ti_pvu), GFP_KERNEL);
sizeof(*)
> + if (!pvu)
> + return -ENOMEM;
> +
> + pvu->pdev = pdev;
> +
> + base = devm_platform_ioremap_resource_byname(pdev, "cfg");
> + if (IS_ERR(base))
> + return PTR_ERR(base);
> +
> + pvu->cfg = devm_regmap_init_mmio(dev, base, &pvu_cfg_regmap_cfg);
> + if (IS_ERR(pvu->cfg))
> + return dev_err_probe(dev, PTR_ERR(pvu->cfg), "failed to init cfg regmap");
> +
> + ret = devm_regmap_field_bulk_alloc(dev, pvu->cfg, pvu->cfg_fields,
> + pvu_cfg_reg_fields, PVU_MAX_CFG_FIELDS);
> + if (ret)
> + return dev_err_probe(dev, ret, "failed to alloc cfg regmap fields");
> +
> + pvu->num_tlbs = pvu_field_read(pvu, PVU_TLBS);
> + pvu->num_entries = pvu_field_read(pvu, PVU_TLB_ENTRIES);
> + dev_info(dev, "TLBs: %d, entries per TLB: %d\n", pvu->num_tlbs,
> + pvu->num_entries);
> +
> + pvu->tlbif_base = devm_platform_ioremap_resource_byname(pdev, "tlbif");
> + if (IS_ERR(pvu->tlbif_base))
> + return PTR_ERR(pvu->tlbif_base);
> +
> + its_node = of_find_compatible_node(0, 0, "arm,gic-v3-its");
> + if (its_node) {
> + u32 pre_its_window[2];
> +
> + ret = of_property_read_u32_array(its_node,
> + "socionext,synquacer-pre-its",
> + pre_its_window,
> + ARRAY_SIZE(pre_its_window));
> + if (ret) {
> + dev_err(dev, "failed to read pre-its property\n");
> + return ret;
> + }
> +
> + ret = pvu_create_region(pvu, pre_its_window[0],
> + pre_its_window[1]);
> + if (ret)
> + return ret;
> + }
> +
> + val = readl(pvu->tlbif_base + PVU_CHAIN);
> + val |= PVU_CHAIN_EN;
> + writel(val, pvu->tlbif_base + PVU_CHAIN);
> +
> + pvu_field_write(pvu, PVU_DMA_CNT, 0);
> + pvu_field_write(pvu, PVU_DMA_CL0, 0);
> + pvu_field_write(pvu, PVU_DMA_CL1, 0);
> + pvu_field_write(pvu, PVU_DMA_CL2, 0);
> + pvu_field_write(pvu, PVU_DMA_CL3, 0);
> + pvu_field_write(pvu, PVU_MAX_VIRTID, NUM_VIRTIDS);
> +
> + ret = platform_get_irq(pdev, 0);
> + if (ret < 0)
> + return dev_err_probe(dev, ret, "failed to get irq\n");
> +
> + ret = devm_request_irq(dev, ret, pvu_fault_isr, 0, dev_name(dev), pvu);
> + if (ret)
> + return dev_err_probe(dev, ret, "failed to request irq\n");
> +
> + pvu_field_write(pvu, PVU_EXC_ENABLE, 1);
> + pvu_field_write(pvu, PVU_ENABLED, 1);
> +
> + dev_set_drvdata(dev, pvu);
> +
> + mutex_lock(&ti_pvu_lock);
> + list_add(&pvu->entry, &ti_pvu_list);
> + mutex_unlock(&ti_pvu_lock);
> +
> + return 0;
> +}
> +
> +static void ti_pvu_remove(struct platform_device *pdev)
> +{
> + struct ti_pvu *pvu = dev_get_drvdata(&pdev->dev);
> +
> + mutex_lock(&ti_pvu_lock);
> + list_del(&pvu->entry);
> + mutex_unlock(&ti_pvu_lock);
> +}
> +
> +static const struct of_device_id ti_pvu_of_match[] = {
> + { .compatible = "ti,am654-pvu", },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, ti_pvu_of_match);
> +
> +static struct platform_driver ti_pvu_driver = {
> + .driver = {
> + .name = "ti-pvu",
> + .of_match_table = ti_pvu_of_match,
> + },
> + .probe = ti_pvu_probe,
> + .remove_new = ti_pvu_remove,
> +};
> +module_platform_driver(ti_pvu_driver);
> diff --git a/include/linux/ti-pvu.h b/include/linux/ti-pvu.h
> new file mode 100644
> index 000000000000..d40642522cf0
> --- /dev/null
> +++ b/include/linux/ti-pvu.h
> @@ -0,0 +1,11 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * TI Peripheral Virtualization Unit driver for static DMA isolation
> + *
> + * Copyright (c) 2024, Siemens AG
> + */
> +
Missing guards.
> +#include <linux/ioport.h>
> +
> +int ti_pvu_create_region(unsigned int virt_id, const struct resource *region);
> +int ti_pvu_remove_region(unsigned int virt_id, const struct resource *region);
Best regards,
Krzysztof
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