Add support for true random number generator provided by the MCU on Turris Omnia. The MCU firmware supports TRNG if the FEAT_TRNG bit is set in features. In that case we bind the rng driver.
Signed-off-by: Marek Behún kabel@kernel.org Reviewed-by: Stefan Roese sr@denx.de --- configs/turris_omnia_defconfig | 1 + drivers/misc/Kconfig | 1 + drivers/misc/turris_omnia_mcu.c | 57 +++++++++++++++++++++++++++++++++ 3 files changed, 59 insertions(+)
diff --git a/configs/turris_omnia_defconfig b/configs/turris_omnia_defconfig index 0df0f3c90b..4c21635ec9 100644 --- a/configs/turris_omnia_defconfig +++ b/configs/turris_omnia_defconfig @@ -107,6 +107,7 @@ CONFIG_NVME_PCI=y CONFIG_PCI_MVEBU=y CONFIG_PINCTRL=y CONFIG_PINCTRL_ARMADA_38X=y +CONFIG_DM_RNG=y CONFIG_DM_RTC=y CONFIG_RTC_ARMADA38X=y CONFIG_SERIAL_PROBE_ALL=y diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig index 041de538fa..6b06888454 100644 --- a/drivers/misc/Kconfig +++ b/drivers/misc/Kconfig @@ -509,6 +509,7 @@ config TURRIS_OMNIA_MCU bool "Enable Turris Omnia MCU driver" depends on DM_I2C depends on DM_GPIO + depends on DM_RNG depends on SYSRESET default y if TARGET_TURRIS_OMNIA help diff --git a/drivers/misc/turris_omnia_mcu.c b/drivers/misc/turris_omnia_mcu.c index 77a0424d61..6b2f17c000 100644 --- a/drivers/misc/turris_omnia_mcu.c +++ b/drivers/misc/turris_omnia_mcu.c @@ -5,15 +5,20 @@ */
#include <common.h> +#include <console.h> #include <dm.h> #include <dm/lists.h> #include <i2c.h> +#include <rng.h> #include <sysreset.h> #include <turris-omnia-mcu-interface.h> #include <asm/byteorder.h> #include <asm/gpio.h> +#include <linux/delay.h> #include <linux/log2.h>
+#define CMD_TRNG_MAX_ENTROPY_LEN 64 + struct turris_omnia_mcu_info { u32 features; }; @@ -282,6 +287,49 @@ U_BOOT_DRIVER(turris_omnia_mcu_sysreset) = { .ops = &omnia_sysreset_ops, };
+static int omnia_rng_read(struct udevice *dev, void *data, size_t count) +{ + u8 buf[1 + CMD_TRNG_MAX_ENTROPY_LEN]; + size_t len; + int ret; + + while (count) { + ret = dm_i2c_read(dev->parent, CMD_TRNG_COLLECT_ENTROPY, buf, + sizeof(buf)); + if (ret) + return ret; + + len = min_t(size_t, buf[0], + min_t(size_t, CMD_TRNG_MAX_ENTROPY_LEN, count)); + + if (!len) { + /* wait 500ms (fail if interrupted), then try again */ + for (int i = 0; i < 5; ++i) { + mdelay(100); + if (ctrlc()) + return -EINTR; + } + continue; + } + + memcpy(data, &buf[1], len); + data += len; + count -= len; + } + + return 0; +} + +static const struct dm_rng_ops omnia_rng_ops = { + .read = omnia_rng_read, +}; + +U_BOOT_DRIVER(turris_omnia_mcu_trng) = { + .name = "turris-omnia-mcu-trng", + .id = UCLASS_RNG, + .ops = &omnia_rng_ops, +}; + static int turris_omnia_mcu_bind(struct udevice *dev) { /* bind MCU GPIOs as a child device */ @@ -336,6 +384,15 @@ static int turris_omnia_mcu_probe(struct udevice *dev) return ret; }
+ /* bind rng if trng is supported */ + if (info->features & FEAT_TRNG) { + ret = device_bind_driver_to_node(dev, "turris-omnia-mcu-trng", + "turris-omnia-mcu-trng", + dev_ofnode(dev), NULL); + if (ret < 0) + return ret; + } + return 0; }