Am Mon, Mar 07, 2022 at 03:40:23PM +0000 schrieb conor.dooley@xxxxxxxxxxxxx:
> From: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
>
> Add a driver to access the hardware random number generator on the
> Polarfire SoC. The hwrng can only be accessed via the system controller,
> so use the mailbox interface the system controller exposes to access the
> hwrng.
>
> Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> ---
> drivers/char/hw_random/Kconfig | 13 ++++
> drivers/char/hw_random/Makefile | 1 +
> drivers/char/hw_random/mpfs-rng.c | 103 ++++++++++++++++++++++++++++++
> 3 files changed, 117 insertions(+)
> create mode 100644 drivers/char/hw_random/mpfs-rng.c
>
> diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
> index 9704963f9d50..69f1fd538589 100644
> --- a/drivers/char/hw_random/Kconfig
> +++ b/drivers/char/hw_random/Kconfig
> @@ -385,6 +385,19 @@ config HW_RANDOM_PIC32
>
> If unsure, say Y.
>
> +config HW_RANDOM_POLARFIRE_SOC
> + tristate "Microchip PolarFire SoC Random Number Generator support"
> + depends on HW_RANDOM && POLARFIRE_SOC_SYS_CTRL
> + help
> + This driver provides kernel-side support for the Random Number
> + Generator hardware found on PolarFire SoC (MPFS).
> +
> + To compile this driver as a module, choose M here. The
> + module will be called mfps_rng.
> +
> + If unsure, say N.
> +
> +
> config HW_RANDOM_MESON
> tristate "Amlogic Meson Random Number Generator support"
> depends on HW_RANDOM
> diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
> index 584d47ba32f7..3e948cf04476 100644
> --- a/drivers/char/hw_random/Makefile
> +++ b/drivers/char/hw_random/Makefile
> @@ -46,3 +46,4 @@ obj-$(CONFIG_HW_RANDOM_CCTRNG) += cctrng.o
> obj-$(CONFIG_HW_RANDOM_XIPHERA) += xiphera-trng.o
> obj-$(CONFIG_HW_RANDOM_ARM_SMCCC_TRNG) += arm_smccc_trng.o
> obj-$(CONFIG_HW_RANDOM_CN10K) += cn10k-rng.o
> +obj-$(CONFIG_HW_RANDOM_POLARFIRE_SOC) += mpfs-rng.o
> diff --git a/drivers/char/hw_random/mpfs-rng.c b/drivers/char/hw_random/mpfs-rng.c
> new file mode 100644
> index 000000000000..a103c765d021
> --- /dev/null
> +++ b/drivers/char/hw_random/mpfs-rng.c
> @@ -0,0 +1,103 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Microchip PolarFire SoC (MPFS) hardware random driver
> + *
> + * Copyright (c) 2020-2022 Microchip Corporation. All rights reserved.
> + *
> + * Author: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/hw_random.h>
> +#include <linux/platform_device.h>
> +#include <soc/microchip/mpfs.h>
> +
> +#define CMD_OPCODE 0x21
> +#define CMD_DATA_SIZE 0U
> +#define CMD_DATA NULL
> +#define MBOX_OFFSET 0U
> +#define RESP_OFFSET 0U
> +#define RNG_RESP_BYTES 32U
> +
> +struct mpfs_rng {
> + struct mpfs_sys_controller *sys_controller;
> + struct hwrng rng;
> +};
> +
> +static int mpfs_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
> +{
> + struct mpfs_rng *rng_priv = container_of(rng, struct mpfs_rng, rng);
> + u32 response_msg[RNG_RESP_BYTES / sizeof(u32)];
> + unsigned int count = 0, copy_size_bytes;
> + int ret;
> +
> + struct mpfs_mss_response response = {
> + .resp_status = 0U,
> + .resp_msg = (u32 *)response_msg,
> + .resp_size = RNG_RESP_BYTES
> + };
> + struct mpfs_mss_msg msg = {
> + .cmd_opcode = CMD_OPCODE,
> + .cmd_data_size = CMD_DATA_SIZE,
> + .response = &response,
> + .cmd_data = CMD_DATA,
> + .mbox_offset = MBOX_OFFSET,
> + .resp_offset = RESP_OFFSET
> + };
> +
> + while (count < max) {
> + ret = mpfs_blocking_transaction(rng_priv->sys_controller, &msg);
> + if (ret)
> + return ret;
> +
> + copy_size_bytes = max - count > RNG_RESP_BYTES ? RNG_RESP_BYTES : max - count;
> + memcpy(buf + count, response_msg, copy_size_bytes);
> +
> + count += copy_size_bytes;
> + if (!wait)
> + break;
> + }
> +
> + return count;
> +}
> +
> +static int mpfs_rng_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct mpfs_rng *rng_priv;
> + int ret;
> +
> + rng_priv = devm_kzalloc(dev, sizeof(*rng_priv), GFP_KERNEL);
> + if (!rng_priv)
> + return -ENOMEM;
> +
> + rng_priv->sys_controller = mpfs_sys_controller_get(&pdev->dev);
> + if (IS_ERR(rng_priv->sys_controller))
> + return dev_err_probe(dev, PTR_ERR(rng_priv->sys_controller),
> + "Failed to register system controller hwrng sub device\n");
> +
> + rng_priv->rng.read = mpfs_rng_read;
> + rng_priv->rng.name = pdev->name;
Is there also some quality estimation, or should this hwrng only be trusted
if it passes validation by userspace?
Thanks,
Dominik
