Re: [PATCH u-boot-mvebu v3 17/18] misc: turris_omnia_mcu: Add support for rng provided by MCU

On 3/27/24 17:23, Marek Behún wrote:

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

Thanks, Stefan

---

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 844a21be47..a08f02196f 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; }

Viele Grüße, Stefan Roese