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From:   Ard Biesheuvel <ardb@kernel.org>
Date:   Wed, 8 Jul 2020 18:41:27 +0300
Message-ID: <CAMj1kXE2bbXR0Yrm009g7917KH7AC9R0AjCNyvdiv1k4r74YiQ@mail.gmail.com>
Subject: Re: [PATCH v3 1/2] tpm: tis: add support for MMIO TPM on SynQuacer
To:     Masahisa Kojima <masahisa.kojima@linaro.org>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        linux-integrity <linux-integrity@vger.kernel.org>,
        Peter Huewe <peterhuewe@gmx.de>, Jason Gunthorpe <jgg@ziepe.ca>
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Sender: linux-kernel-owner@vger.kernel.org
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On Wed, 8 Jul 2020 at 16:15, Masahisa Kojima <masahisa.kojima@linaro.org> wrote:
>
> When fitted, the SynQuacer platform exposes its SPI TPM via a MMIO
> window that is backed by the SPI command sequencer in the SPI bus
> controller. This arrangement has the limitation that only byte size
> accesses are supported, and so we'll need to provide a separate module
> that take this into account.
>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> Signed-off-by: Masahisa Kojima <masahisa.kojima@linaro.org>

Hello Masahisa,

This looks fine to me, but I won't be able to test it any time soon,
unfortunately.

One suggestion: could you allocate a ACPI _HID for this device, and
add support for it to the driver as well?

> ---
>  drivers/char/tpm/Kconfig             |  12 ++
>  drivers/char/tpm/Makefile            |   1 +
>  drivers/char/tpm/tpm_tis_synquacer.c | 196 +++++++++++++++++++++++++++
>  3 files changed, 209 insertions(+)
>  create mode 100644 drivers/char/tpm/tpm_tis_synquacer.c
>
> diff --git a/drivers/char/tpm/Kconfig b/drivers/char/tpm/Kconfig
> index 58b4c573d176..a18c314da211 100644
> --- a/drivers/char/tpm/Kconfig
> +++ b/drivers/char/tpm/Kconfig
> @@ -74,6 +74,18 @@ config TCG_TIS_SPI_CR50
>           If you have a H1 secure module running Cr50 firmware on SPI bus,
>           say Yes and it will be accessible from within Linux.
>
> +config TCG_TIS_SYNQUACER
> +       tristate "TPM Interface Specification 1.2 Interface / TPM 2.0 FIFO Interface (MMIO - SynQuacer)"
> +       depends on ARCH_SYNQUACER
> +       select TCG_TIS_CORE
> +       help
> +         If you have a TPM security chip that is compliant with the
> +         TCG TIS 1.2 TPM specification (TPM1.2) or the TCG PTP FIFO
> +         specification (TPM2.0) say Yes and it will be accessible from
> +         within Linux on Socionext SynQuacer platform.
> +         To compile this driver as a module, choose  M here;
> +         the module will be called tpm_tis_synquacer.
> +
>  config TCG_TIS_I2C_ATMEL
>         tristate "TPM Interface Specification 1.2 Interface (I2C - Atmel)"
>         depends on I2C
> diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
> index 9567e5197f74..84db4fb3a9c9 100644
> --- a/drivers/char/tpm/Makefile
> +++ b/drivers/char/tpm/Makefile
> @@ -21,6 +21,7 @@ tpm-$(CONFIG_EFI) += eventlog/efi.o
>  tpm-$(CONFIG_OF) += eventlog/of.o
>  obj-$(CONFIG_TCG_TIS_CORE) += tpm_tis_core.o
>  obj-$(CONFIG_TCG_TIS) += tpm_tis.o
> +obj-$(CONFIG_TCG_TIS_SYNQUACER) += tpm_tis_synquacer.o
>
>  obj-$(CONFIG_TCG_TIS_SPI) += tpm_tis_spi.o
>  tpm_tis_spi-y := tpm_tis_spi_main.o
> diff --git a/drivers/char/tpm/tpm_tis_synquacer.c b/drivers/char/tpm/tpm_tis_synquacer.c
> new file mode 100644
> index 000000000000..51f0aedcedcc
> --- /dev/null
> +++ b/drivers/char/tpm/tpm_tis_synquacer.c
> @@ -0,0 +1,196 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2020 Linaro Ltd.
> + *
> + * This device driver implements MMIO TPM on SynQuacer Platform.
> + */
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/slab.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/kernel.h>
> +#include "tpm.h"
> +#include "tpm_tis_core.h"
> +
> +struct tpm_info {
> +       struct resource res;
> +       /* irq > 0 means: use irq $irq;
> +        * irq = 0 means: autoprobe for an irq;
> +        * irq = -1 means: no irq support
> +        */
> +       int irq;
> +};
> +
> +struct tpm_tis_tcg_phy {
> +       struct tpm_tis_data priv;
> +       void __iomem *iobase;
> +};
> +
> +static inline struct tpm_tis_tcg_phy *to_tpm_tis_tcg_phy(struct tpm_tis_data *data)
> +{
> +       return container_of(data, struct tpm_tis_tcg_phy, priv);
> +}
> +
> +static int tpm_tcg_read_bytes(struct tpm_tis_data *data, u32 addr, u16 len,
> +                             u8 *result)
> +{
> +       struct tpm_tis_tcg_phy *phy = to_tpm_tis_tcg_phy(data);
> +
> +       while (len--)
> +               *result++ = ioread8(phy->iobase + addr);
> +
> +       return 0;
> +}
> +
> +static int tpm_tcg_write_bytes(struct tpm_tis_data *data, u32 addr, u16 len,
> +                              const u8 *value)
> +{
> +       struct tpm_tis_tcg_phy *phy = to_tpm_tis_tcg_phy(data);
> +
> +       while (len--)
> +               iowrite8(*value++, phy->iobase + addr);
> +
> +       return 0;
> +}
> +
> +static int tpm_tcg_read16_bw(struct tpm_tis_data *data, u32 addr, u16 *result)
> +{
> +       struct tpm_tis_tcg_phy *phy = to_tpm_tis_tcg_phy(data);
> +
> +       /*
> +        * Due to the limitation of SPI controller on SynQuacer,
> +        * 16/32 bits access must be done in byte-wise and descending order.
> +        */
> +       *result = (ioread8(phy->iobase + addr + 1) << 8) |
> +                 (ioread8(phy->iobase + addr));
> +
> +       return 0;
> +}
> +
> +static int tpm_tcg_read32_bw(struct tpm_tis_data *data, u32 addr, u32 *result)
> +{
> +       struct tpm_tis_tcg_phy *phy = to_tpm_tis_tcg_phy(data);
> +
> +       /*
> +        * Due to the limitation of SPI controller on SynQuacer,
> +        * 16/32 bits access must be done in byte-wise and descending order.
> +        */
> +       *result = (ioread8(phy->iobase + addr + 3) << 24) |
> +                 (ioread8(phy->iobase + addr + 2) << 16) |
> +                 (ioread8(phy->iobase + addr + 1) << 8) |
> +                 (ioread8(phy->iobase + addr));
> +
> +       return 0;
> +}
> +
> +static int tpm_tcg_write32_bw(struct tpm_tis_data *data, u32 addr, u32 value)
> +{
> +       struct tpm_tis_tcg_phy *phy = to_tpm_tis_tcg_phy(data);
> +
> +       /*
> +        * Due to the limitation of SPI controller on SynQuacer,
> +        * 16/32 bits access must be done in byte-wise and descending order.
> +        */
> +       iowrite8(value >> 24, phy->iobase + addr + 3);
> +       iowrite8(value >> 16, phy->iobase + addr + 2);
> +       iowrite8(value >> 8, phy->iobase + addr + 1);
> +       iowrite8(value, phy->iobase + addr);
> +
> +       return 0;
> +}
> +
> +static const struct tpm_tis_phy_ops tpm_tcg_bw = {
> +       .read_bytes     = tpm_tcg_read_bytes,
> +       .write_bytes    = tpm_tcg_write_bytes,
> +       .read16         = tpm_tcg_read16_bw,
> +       .read32         = tpm_tcg_read32_bw,
> +       .write32        = tpm_tcg_write32_bw,
> +};
> +
> +static int tpm_tis_synquacer_init(struct device *dev, struct tpm_info *tpm_info)
> +{
> +       struct tpm_tis_tcg_phy *phy;
> +       int irq = -1;
> +
> +       phy = devm_kzalloc(dev, sizeof(struct tpm_tis_tcg_phy), GFP_KERNEL);
> +       if (phy == NULL)
> +               return -ENOMEM;
> +
> +       phy->iobase = devm_ioremap_resource(dev, &tpm_info->res);
> +       if (IS_ERR(phy->iobase))
> +               return PTR_ERR(phy->iobase);
> +
> +       return tpm_tis_core_init(dev, &phy->priv, irq, &tpm_tcg_bw,
> +                                ACPI_HANDLE(dev));
> +}
> +
> +static SIMPLE_DEV_PM_OPS(tpm_tis_synquacer_pm, tpm_pm_suspend, tpm_tis_resume);
> +
> +static int tpm_tis_synquacer_probe(struct platform_device *pdev)
> +{
> +       struct tpm_info tpm_info = {};
> +       struct resource *res;
> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       if (res == NULL) {
> +               dev_err(&pdev->dev, "no memory resource defined\n");
> +               return -ENODEV;
> +       }
> +       tpm_info.res = *res;
> +
> +       tpm_info.irq = -1;
> +
> +       return tpm_tis_synquacer_init(&pdev->dev, &tpm_info);
> +}
> +
> +static int tpm_tis_synquacer_remove(struct platform_device *pdev)
> +{
> +       struct tpm_chip *chip = dev_get_drvdata(&pdev->dev);
> +
> +       tpm_chip_unregister(chip);
> +       tpm_tis_remove(chip);
> +
> +       return 0;
> +}
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id tis_synquacer_of_platform_match[] = {
> +       {.compatible = "socionext,synquacer-tpm-mmio"},
> +       {},
> +};
> +MODULE_DEVICE_TABLE(of, tis_synquacer_of_platform_match);
> +#endif
> +
> +static struct platform_driver tis_synquacer_drv = {
> +       .probe = tpm_tis_synquacer_probe,
> +       .remove = tpm_tis_synquacer_remove,
> +       .driver = {
> +               .name           = "tpm_tis_synquacer",
> +               .pm             = &tpm_tis_synquacer_pm,
> +               .of_match_table = of_match_ptr(tis_synquacer_of_platform_match),
> +       },
> +};
> +
> +static int __init init_tis_synquacer(void)
> +{
> +       int rc;
> +
> +       rc = platform_driver_register(&tis_synquacer_drv);
> +       if (rc)
> +               return rc;
> +
> +       return 0;
> +}
> +
> +static void __exit cleanup_tis_synquacer(void)
> +{
> +       platform_driver_unregister(&tis_synquacer_drv);
> +}
> +
> +module_init(init_tis_synquacer);
> +module_exit(cleanup_tis_synquacer);
> +MODULE_AUTHOR("Masahisa Kojima (masahisa.kojima@linaro.org)");
> +MODULE_DESCRIPTION("TPM MMIO Driver for Socionext SynQuacer platform");
> +MODULE_VERSION("2.0");
> +MODULE_LICENSE("GPL");
> --
> 2.20.1
>