Message-ID: <20200723023634.GI45081@linux.intel.com>
Date:   Thu, 23 Jul 2020 05:36:34 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     Masahisa Kojima <masahisa.kojima@...aro.org>
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        ardb@...nel.org, devicetree@...r.kernel.org,
        linux-integrity@...r.kernel.org, peterhuewe@....de, jgg@...pe.ca
Subject: Re: [PATCH v4 1/2] tpm: tis: add support for MMIO TPM on SynQuacer

On Fri, Jul 17, 2020 at 05:49:31PM +0900, Masahisa Kojima 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@...nel.org>
> Signed-off-by: Masahisa Kojima <masahisa.kojima@...aro.org>
> ---
>  drivers/char/tpm/Kconfig             |  12 ++
>  drivers/char/tpm/Makefile            |   1 +
>  drivers/char/tpm/tpm_tis_synquacer.c | 209 +++++++++++++++++++++++++++
>  3 files changed, 222 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..ac2a1d2a5001
> --- /dev/null
> +++ b/drivers/char/tpm/tpm_tis_synquacer.c
> @@ -0,0 +1,209 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2020 Linaro Ltd.
> + *
> + * This device driver implements MMIO TPM on SynQuacer Platform.
> + */
> +#include <linux/acpi.h>
> +#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_tis_synquacer_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;
> +};

According to the coding style, multi-line comments must begin with an
empty line.

Also it would be preferable to have the comment prepending the struct
for easier read:

/*
 * irq > 0 means: use irq $irq;
 * irq = 0 means: autoprobe for an irq;
 * irq = -1 means: no irq support
 */
struct tpm_tis_synquacer_info {

> +
> +struct tpm_tis_synquacer_phy {
> +	struct tpm_tis_data priv;
> +	void __iomem *iobase;
> +};
> +
> +static inline struct tpm_tis_synquacer_phy *to_tpm_tis_tcg_phy(struct tpm_tis_data *data)
> +{
> +	return container_of(data, struct tpm_tis_synquacer_phy, priv);
> +}
> +
> +static int tpm_tis_synquacer_read_bytes(struct tpm_tis_data *data, u32 addr,
> +					u16 len, u8 *result)
> +{
> +	struct tpm_tis_synquacer_phy *phy = to_tpm_tis_tcg_phy(data);
> +
> +	while (len--)
> +		*result++ = ioread8(phy->iobase + addr);
> +
> +	return 0;
> +}
> +
> +static int tpm_tis_synquacer_write_bytes(struct tpm_tis_data *data, u32 addr,
> +					 u16 len, const u8 *value)
> +{
> +	struct tpm_tis_synquacer_phy *phy = to_tpm_tis_tcg_phy(data);
> +
> +	while (len--)
> +		iowrite8(*value++, phy->iobase + addr);
> +
> +	return 0;
> +}
> +
> +static int tpm_tis_synquacer_read16_bw(struct tpm_tis_data *data,
> +				       u32 addr, u16 *result)
> +{
> +	struct tpm_tis_synquacer_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_tis_synquacer_read32_bw(struct tpm_tis_data *data,
> +				       u32 addr, u32 *result)
> +{
> +	struct tpm_tis_synquacer_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_tis_synquacer_write32_bw(struct tpm_tis_data *data,
> +					u32 addr, u32 value)
> +{
> +	struct tpm_tis_synquacer_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_tis_synquacer_read_bytes,
> +	.write_bytes	= tpm_tis_synquacer_write_bytes,
> +	.read16		= tpm_tis_synquacer_read16_bw,
> +	.read32		= tpm_tis_synquacer_read32_bw,
> +	.write32	= tpm_tis_synquacer_write32_bw,
> +};
> +
> +static int tpm_tis_synquacer_init(struct device *dev,
> +				  struct tpm_tis_synquacer_info *tpm_info)
> +{
> +	struct tpm_tis_synquacer_phy *phy;
> +
> +	phy = devm_kzalloc(dev, sizeof(struct tpm_tis_synquacer_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, tpm_info->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_tis_synquacer_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
> +
> +#ifdef CONFIG_ACPI
> +static const struct acpi_device_id tpm_synquacer_acpi_tbl[] = {
> +	{ "SCX0009" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(acpi, tpm_synquacer_acpi_tbl);
> +#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),
> +		.acpi_match_table = ACPI_PTR(tpm_synquacer_acpi_tbl),
> +	},
> +};
> +
> +static int __init tpm_tis_synquacer_module_init(void)
> +{
> +	int rc;
> +
> +	rc = platform_driver_register(&tis_synquacer_drv);
> +	if (rc)
> +		return rc;
> +
> +	return 0;
> +}
> +
> +static void __exit tpm_tis_synquacer_module_exit(void)
> +{
> +	platform_driver_unregister(&tis_synquacer_drv);
> +}
> +
> +module_init(tpm_tis_synquacer_module_init);
> +module_exit(tpm_tis_synquacer_module_exit);
> +MODULE_AUTHOR("Masahisa Kojima (masahisa.kojima@...aro.org)");

It is completely redundant field because authorship is part of the
commit object itself. And it does not tell the truth after a while
anyway. MODULE_AUTHOR() made more sense before there was any sort of
legit versio control in place.

I think it would be better not to have it as we don't have any use
for this data. It is just cruft hanging there.

> +MODULE_DESCRIPTION("TPM MMIO Driver for Socionext SynQuacer platform");
> +MODULE_VERSION("2.0");
> +MODULE_LICENSE("GPL");
> -- 
> 2.20.1
> 

/Jarkko

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