From b3ed8645c45567b598bef0868dca166f8ed166a0 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marek=20Beh=C3=BAn?= Date: Mon, 1 Jul 2024 13:30:08 +0200 Subject: [PATCH 06/11] platform: cznic: turris-omnia-mcu: Add support for MCU provided TRNG MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Add support for true random number generator provided by the MCU. New Omnia boards come without the Atmel SHA204-A chip. Instead the crypto functionality is provided by new microcontroller, which has a TRNG peripheral. Signed-off-by: Marek Behún Acked-by: Bartosz Golaszewski Link: https://lore.kernel.org/r/20240701113010.16447-7-kabel@kernel.org Signed-off-by: Arnd Bergmann --- drivers/platform/cznic/Kconfig | 2 + drivers/platform/cznic/Makefile | 1 + .../platform/cznic/turris-omnia-mcu-base.c | 6 +- .../platform/cznic/turris-omnia-mcu-gpio.c | 2 +- .../platform/cznic/turris-omnia-mcu-trng.c | 105 ++++++++++++++++++ drivers/platform/cznic/turris-omnia-mcu.h | 8 ++ 6 files changed, 122 insertions(+), 2 deletions(-) create mode 100644 drivers/platform/cznic/turris-omnia-mcu-trng.c --- a/drivers/platform/cznic/Kconfig +++ b/drivers/platform/cznic/Kconfig @@ -18,6 +18,7 @@ config TURRIS_OMNIA_MCU depends on I2C select GPIOLIB select GPIOLIB_IRQCHIP + select HW_RANDOM select RTC_CLASS select WATCHDOG_CORE help @@ -27,6 +28,7 @@ config TURRIS_OMNIA_MCU - board poweroff into true low power mode (with voltage regulators disabled) and the ability to configure wake up from this mode (via rtcwake) + - true random number generator (if available on the MCU) - MCU watchdog - GPIO pins - to get front button press events (the front button can be --- a/drivers/platform/cznic/Makefile +++ b/drivers/platform/cznic/Makefile @@ -4,4 +4,5 @@ obj-$(CONFIG_TURRIS_OMNIA_MCU) += turris turris-omnia-mcu-y := turris-omnia-mcu-base.o turris-omnia-mcu-y += turris-omnia-mcu-gpio.o turris-omnia-mcu-y += turris-omnia-mcu-sys-off-wakeup.o +turris-omnia-mcu-y += turris-omnia-mcu-trng.o turris-omnia-mcu-y += turris-omnia-mcu-watchdog.o --- a/drivers/platform/cznic/turris-omnia-mcu-base.c +++ b/drivers/platform/cznic/turris-omnia-mcu-base.c @@ -380,7 +380,11 @@ static int omnia_mcu_probe(struct i2c_cl if (err) return err; - return omnia_mcu_register_gpiochip(mcu); + err = omnia_mcu_register_gpiochip(mcu); + if (err) + return err; + + return omnia_mcu_register_trng(mcu); } static const struct of_device_id of_omnia_mcu_match[] = { --- a/drivers/platform/cznic/turris-omnia-mcu-gpio.c +++ b/drivers/platform/cznic/turris-omnia-mcu-gpio.c @@ -194,7 +194,7 @@ static const struct omnia_gpio omnia_gpi }; /* mapping from interrupts to indexes of GPIOs in the omnia_gpios array */ -static const u8 omnia_int_to_gpio_idx[32] = { +const u8 omnia_int_to_gpio_idx[32] = { [__bf_shf(OMNIA_INT_CARD_DET)] = 4, [__bf_shf(OMNIA_INT_MSATA_IND)] = 5, [__bf_shf(OMNIA_INT_USB30_OVC)] = 6, --- /dev/null +++ b/drivers/platform/cznic/turris-omnia-mcu-trng.c @@ -0,0 +1,105 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * CZ.NIC's Turris Omnia MCU TRNG driver + * + * 2024 by Marek Behún + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "../../gpio/gpiolib.h" + +#include +#include "turris-omnia-mcu.h" + +#define OMNIA_CMD_TRNG_MAX_ENTROPY_LEN 64 + +static irqreturn_t omnia_trng_irq_handler(int irq, void *dev_id) +{ + struct omnia_mcu *mcu = dev_id; + + complete(&mcu->trng_entropy_ready); + + return IRQ_HANDLED; +} + +static int omnia_trng_read(struct hwrng *rng, void *data, size_t max, bool wait) +{ + struct omnia_mcu *mcu = container_of(rng, struct omnia_mcu, trng); + u8 reply[1 + OMNIA_CMD_TRNG_MAX_ENTROPY_LEN]; + int err, bytes; + + if (!wait && !completion_done(&mcu->trng_entropy_ready)) + return 0; + + do { + if (wait_for_completion_interruptible(&mcu->trng_entropy_ready)) + return -ERESTARTSYS; + + err = omnia_cmd_read(mcu->client, + OMNIA_CMD_TRNG_COLLECT_ENTROPY, + reply, sizeof(reply)); + if (err) + return err; + + bytes = min3(reply[0], max, OMNIA_CMD_TRNG_MAX_ENTROPY_LEN); + } while (wait && !bytes); + + memcpy(data, &reply[1], bytes); + + return bytes; +} + +int omnia_mcu_register_trng(struct omnia_mcu *mcu) +{ + struct device *dev = &mcu->client->dev; + u8 irq_idx, dummy; + int irq, err; + + if (!(mcu->features & OMNIA_FEAT_TRNG)) + return 0; + + irq_idx = omnia_int_to_gpio_idx[__bf_shf(OMNIA_INT_TRNG)]; + irq = gpiod_to_irq(gpiochip_get_desc(&mcu->gc, irq_idx)); + if (!irq) + return dev_err_probe(dev, -ENXIO, "Cannot get TRNG IRQ\n"); + + /* + * If someone else cleared the TRNG interrupt but did not read the + * entropy, a new interrupt won't be generated, and entropy collection + * will be stuck. Ensure an interrupt will be generated by executing + * the collect entropy command (and discarding the result). + */ + err = omnia_cmd_read(mcu->client, OMNIA_CMD_TRNG_COLLECT_ENTROPY, + &dummy, 1); + if (err) + return err; + + init_completion(&mcu->trng_entropy_ready); + + err = devm_request_threaded_irq(dev, irq, NULL, omnia_trng_irq_handler, + IRQF_ONESHOT, "turris-omnia-mcu-trng", + mcu); + if (err) + return dev_err_probe(dev, err, "Cannot request TRNG IRQ\n"); + + mcu->trng.name = "turris-omnia-mcu-trng"; + mcu->trng.read = omnia_trng_read; + + err = devm_hwrng_register(dev, &mcu->trng); + if (err) + return dev_err_probe(dev, err, "Cannot register TRNG\n"); + + return 0; +} --- a/drivers/platform/cznic/turris-omnia-mcu.h +++ b/drivers/platform/cznic/turris-omnia-mcu.h @@ -9,7 +9,9 @@ #define __TURRIS_OMNIA_MCU_H #include +#include #include +#include #include #include #include @@ -47,6 +49,10 @@ struct omnia_mcu { /* MCU watchdog */ struct watchdog_device wdt; + + /* true random number generator */ + struct hwrng trng; + struct completion trng_entropy_ready; }; int omnia_cmd_write_read(const struct i2c_client *client, @@ -176,11 +182,13 @@ static inline int omnia_cmd_read_u8(cons return omnia_cmd_read(client, cmd, reply, sizeof(*reply)); } +extern const u8 omnia_int_to_gpio_idx[32]; extern const struct attribute_group omnia_mcu_gpio_group; extern const struct attribute_group omnia_mcu_poweroff_group; int omnia_mcu_register_gpiochip(struct omnia_mcu *mcu); int omnia_mcu_register_sys_off_and_wakeup(struct omnia_mcu *mcu); +int omnia_mcu_register_trng(struct omnia_mcu *mcu); int omnia_mcu_register_watchdog(struct omnia_mcu *mcu); #endif /* __TURRIS_OMNIA_MCU_H */