From: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx> Normally the platform firmware is responsible for taking a Trusted Platform Module out of reset on boot and storing measurements into it. However if the platform firmware is incapable of doing that -- as is the case on the Raspberry Pi -- then the onus is on the kernel to take the TPM out of reset before trying to attach a driver to it. Provide a reset driver for such platforms. The Infineon SLB9670 TPM requires a specific reset sequence on its RST# pin which is documented in sections 5.4 and 5.5 of the datasheet: https://www.infineon.com/dgdl/Infineon-SLB%209670VQ2.0-DataSheet-v01_04-EN.pdf?fileId=5546d4626fc1ce0b016fc78270350cd6 The sequence with minimum wait intervals is as follows: deassert RST# wait at least 60 ms assert RST# wait at least 2 usecs deassert RST# wait at least 60 ms assert RST# wait at least 2 usecs deassert RST# wait at least 60 ms before issuing the first TPM command Signed-off-by: Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx> Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx> --- drivers/reset/Kconfig | 9 +++ drivers/reset/Makefile | 1 + drivers/reset/reset-slb9670.c | 141 ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 151 insertions(+) create mode 100644 drivers/reset/reset-slb9670.c diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig index ccd59dd..3296e33 100644 --- a/drivers/reset/Kconfig +++ b/drivers/reset/Kconfig @@ -229,6 +229,15 @@ config RESET_SIMPLE - Allwinner SoCs - SiFive FU740 SoCs +config RESET_SLB9670 + tristate "Infineon SLB9670 TPM Reset Driver" + depends on TCG_TIS_SPI + help + This enables the reset driver for the Infineon SLB9670 Trusted + Platform Module. Only say Y here if your platform firmware is + incapable of taking the TPM out of reset on boot, requiring the + kernel to do so. + config RESET_SOCFPGA bool "SoCFPGA Reset Driver" if COMPILE_TEST && (!ARM || !ARCH_INTEL_SOCFPGA) default ARM && ARCH_INTEL_SOCFPGA diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile index 8270da8..d9c182e 100644 --- a/drivers/reset/Makefile +++ b/drivers/reset/Makefile @@ -30,6 +30,7 @@ obj-$(CONFIG_RESET_RASPBERRYPI) += reset-raspberrypi.o obj-$(CONFIG_RESET_RZG2L_USBPHY_CTRL) += reset-rzg2l-usbphy-ctrl.o obj-$(CONFIG_RESET_SCMI) += reset-scmi.o obj-$(CONFIG_RESET_SIMPLE) += reset-simple.o +obj-$(CONFIG_RESET_SLB9670) += reset-slb9670.o obj-$(CONFIG_RESET_SOCFPGA) += reset-socfpga.o obj-$(CONFIG_RESET_SUNPLUS) += reset-sunplus.o obj-$(CONFIG_RESET_SUNXI) += reset-sunxi.o diff --git a/drivers/reset/reset-slb9670.c b/drivers/reset/reset-slb9670.c new file mode 100644 index 00000000..cc09ab5 --- /dev/null +++ b/drivers/reset/reset-slb9670.c @@ -0,0 +1,141 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Reset driver for Infineon SLB9670 Trusted Platform Module + * + * Copyright (C) 2022 KUNBUS GmbH + */ + +#include <linux/delay.h> +#include <linux/gpio/consumer.h> +#include <linux/mod_devicetable.h> +#include <linux/platform_device.h> +#include <linux/reset-controller.h> + +/* + * Time intervals used in the reset sequence: + * + * RSTIN: minimum time to hold the reset line deasserted + * WRST: minimum time to hold the reset line asserted + */ +#define SLB9670_TIME_RSTIN 60 /* msecs */ +#define SLB9670_TIME_WRST 2 /* usecs */ + +struct reset_slb9670 { + struct reset_controller_dev rcdev; + struct gpio_desc *gpio; +}; + +static inline struct reset_slb9670 * +to_reset_slb9670(struct reset_controller_dev *rcdev) +{ + return container_of(rcdev, struct reset_slb9670, rcdev); +} + +static int reset_slb9670_assert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + struct reset_slb9670 *reset_slb9670 = to_reset_slb9670(rcdev); + + gpiod_set_value(reset_slb9670->gpio, 1); + return 0; +} + +static int reset_slb9670_deassert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + struct reset_slb9670 *reset_slb9670 = to_reset_slb9670(rcdev); + + /* + * Perform the reset sequence: Deassert and assert the reset line twice + * and wait the respective time intervals. After a last wait interval + * of RSTIN the chip is ready to receive the first command. + */ + gpiod_set_value(reset_slb9670->gpio, 0); + msleep(SLB9670_TIME_RSTIN); + gpiod_set_value(reset_slb9670->gpio, 1); + udelay(SLB9670_TIME_WRST); + gpiod_set_value(reset_slb9670->gpio, 0); + msleep(SLB9670_TIME_RSTIN); + gpiod_set_value(reset_slb9670->gpio, 1); + udelay(SLB9670_TIME_WRST); + gpiod_set_value(reset_slb9670->gpio, 0); + msleep(SLB9670_TIME_RSTIN); + + return 0; +} + +static int reset_slb9670_reset(struct reset_controller_dev *rcdev, + unsigned long id) +{ + int ret; + + ret = reset_slb9670_assert(rcdev, id); + if (ret) + return ret; + + return reset_slb9670_deassert(rcdev, id); +} + +static int reset_slb9670_status(struct reset_controller_dev *rcdev, + unsigned long id) +{ + struct reset_slb9670 *reset_slb9670 = to_reset_slb9670(rcdev); + + return gpiod_get_value(reset_slb9670->gpio); +} + +static const struct reset_control_ops reset_slb9670_ops = { + .assert = reset_slb9670_assert, + .deassert = reset_slb9670_deassert, + .reset = reset_slb9670_reset, + .status = reset_slb9670_status, +}; + +static int reset_slb9670_of_xlate(struct reset_controller_dev *rcdev, + const struct of_phandle_args *reset_spec) +{ + return 0; +} + +static int reset_slb9670_probe(struct platform_device *pdev) +{ + struct reset_slb9670 *reset_slb9670; + struct device *dev = &pdev->dev; + + reset_slb9670 = devm_kzalloc(dev, sizeof(*reset_slb9670), GFP_KERNEL); + if (!reset_slb9670) + return -ENOMEM; + + reset_slb9670->gpio = devm_gpiod_get(dev, "reset", GPIOD_ASIS); + if (IS_ERR(reset_slb9670->gpio)) + return dev_err_probe(dev, PTR_ERR(reset_slb9670->gpio), + "cannot get reset gpio\n"); + + reset_slb9670->rcdev.nr_resets = 1; + reset_slb9670->rcdev.owner = THIS_MODULE; + reset_slb9670->rcdev.of_node = dev->of_node; + reset_slb9670->rcdev.ops = &reset_slb9670_ops; + reset_slb9670->rcdev.of_xlate = reset_slb9670_of_xlate; + reset_slb9670->rcdev.of_reset_n_cells = 0; + + return devm_reset_controller_register(dev, &reset_slb9670->rcdev); +} + +static const struct of_device_id reset_slb9670_dt_ids[] = { + { .compatible = "infineon,slb9670-reset" }, + { /* sentinel */ }, +}; +MODULE_DEVICE_TABLE(of, reset_slb9670_dt_ids); + +static struct platform_driver reset_slb9670_driver = { + .probe = reset_slb9670_probe, + .driver = { + .name = "reset-slb9670", + .of_match_table = reset_slb9670_dt_ids, + }, +}; +module_platform_driver(reset_slb9670_driver); + +MODULE_DESCRIPTION("Infineon SLB9670 TPM Reset Driver"); +MODULE_AUTHOR("Lino Sanfilippo <l.sanfilippo@xxxxxxxxxx>"); +MODULE_LICENSE("GPL"); -- 2.40.1
