[PATCH v3 3/8] stm32mp1: rng: Add a driver for random number generator(rng) device

Patrick DELAUNAY
2019-12-16T11:58:01Z

Hi Sugosh,

> From: U-Boot <u-boot-bounces@lists.denx.de> On Behalf Of Sughosh Ganu
> Sent: vendredi 13 dÃ©cembre 2019 08:14
>
> Add a driver for the rng device found on stm32mp1 platforms. The driver provides
> a routine for reading the random number seed from the hardware device.
>
> Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>
> Reviewed-by: Patrice Chotard <patrice.chotard@st.com>

Acked-by: Patrick Delaunay <patrick.delaunay@st.com>

Thanks.

> ---
> drivers/rng/Kconfig | 7 ++
> drivers/rng/Makefile | 1 +
> drivers/rng/stm32mp1_rng.c | 158
> +++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 166 insertions(+)
> create mode 100644 drivers/rng/stm32mp1_rng.c
>
> diff --git a/drivers/rng/Kconfig b/drivers/rng/Kconfig index dd44cc0..5fc11db
> 100644
> --- a/drivers/rng/Kconfig
> +++ b/drivers/rng/Kconfig
> @@ -5,3 +5,10 @@ config DM_RNG
> Enable driver model for random number generator(rng) devices.
> This interface is used to initialise the rng device and to
> read the random seed from the device.
> +
> +config RNG_STM32MP1
> + bool "Enable random number generator for STM32MP1"
> + depends on ARCH_STM32MP && DM_RNG
> + default n
> + help
> + Enable STM32MP1 rng driver.
> diff --git a/drivers/rng/Makefile b/drivers/rng/Makefile index 311705b..699beb3
> 100644
> --- a/drivers/rng/Makefile
> +++ b/drivers/rng/Makefile
> @@ -4,3 +4,4 @@
> #
>
> obj-$(CONFIG_DM_RNG) += rng-uclass.o
> +obj-$(CONFIG_RNG_STM32MP1) += stm32mp1_rng.o
> diff --git a/drivers/rng/stm32mp1_rng.c b/drivers/rng/stm32mp1_rng.c new file
> mode 100644 index 0000000..5cd736d
> --- /dev/null
> +++ b/drivers/rng/stm32mp1_rng.c
> @@ -0,0 +1,158 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Copyright (c) 2019, Linaro Limited
> + */
> +
> +#include <common.h>
> +#include <clk.h>
> +#include <dm.h>
> +#include <reset.h>
> +#include <rng.h>
> +
> +#include <asm/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/kernel.h>
> +
> +#define RNG_CR 0x00
> +#define RNG_CR_RNGEN BIT(2)
> +#define RNG_CR_CED BIT(5)
> +
> +#define RNG_SR 0x04
> +#define RNG_SR_SEIS BIT(6)
> +#define RNG_SR_CEIS BIT(5)
> +#define RNG_SR_SECS BIT(2)
> +#define RNG_SR_DRDY BIT(0)
> +
> +#define RNG_DR 0x08
> +
> +struct stm32_rng_platdata {
> + fdt_addr_t base;
> + struct clk clk;
> + struct reset_ctl rst;
> +};
> +
> +static int stm32_rng_read(struct udevice *dev, void *data, size_t len)
> +{
> + int retval = 0, i;
> + u32 sr, count, reg;
> + size_t increment;
> + struct stm32_rng_platdata *pdata = dev_get_platdata(dev);
> +
> + while (len > 0) {
> + retval = readl_poll_timeout(pdata->base + RNG_SR, sr,
> + sr & RNG_SR_DRDY, 10000);
> + if (retval)
> + return retval;
> +
> + if (sr & (RNG_SR_SEIS | RNG_SR_SECS)) {
> + /* As per SoC TRM */
> + clrbits_le32(pdata->base + RNG_SR, RNG_SR_SEIS);
> + for (i = 0; i < 12; i++)
> + readl(pdata->base + RNG_DR);
> + if (readl(pdata->base + RNG_SR) & RNG_SR_SEIS) {
> + printf("RNG Noise");
> + return -EIO;
> + }
> + /* start again */
> + continue;
> + }
> +
> + count = 4;
> + while (len && count) {
> + reg = readl(pdata->base + RNG_DR);
> + memcpy(data, &reg, min(len, sizeof(u32)));
> + increment = min(len, sizeof(u32));
> + data += increment;
> + retval += increment;
> + len -= increment;
> + count--;
> + }
> + }
> +
> + return retval;
> +}
> +
> +static int stm32_rng_init(struct stm32_rng_platdata *pdata) {
> + int err;
> +
> + err = clk_enable(&pdata->clk);
> + if (err)
> + return err;
> +
> + /* Disable CED */
> + writel(RNG_CR_RNGEN | RNG_CR_CED, pdata->base + RNG_CR);
> +
> + /* clear error indicators */
> + writel(0, pdata->base + RNG_SR);
> +
> + return 0;
> +}
> +
> +static int stm32_rng_cleanup(struct stm32_rng_platdata *pdata) {
> +
> + writel(0, pdata->base + RNG_CR);
> +
> + return clk_disable(&pdata->clk);
> +}
> +
> +static int stm32_rng_probe(struct udevice *dev) {
> + struct stm32_rng_platdata *pdata = dev_get_platdata(dev);
> +
> + reset_assert(&pdata->rst);
> + udelay(20);
> + reset_deassert(&pdata->rst);
> +
> + return stm32_rng_init(pdata);
> +}
> +
> +static int stm32_rng_remove(struct udevice *dev) {
> + struct stm32_rng_platdata *pdata = dev_get_platdata(dev);
> +
> + return stm32_rng_cleanup(pdata);
> +}
> +
> +static int stm32_rng_ofdata_to_platdata(struct udevice *dev) {
> + struct stm32_rng_platdata *pdata = dev_get_platdata(dev);
> + int err;
> +
> + pdata->base = dev_read_addr(dev);
> + if (!pdata->base)
> + return -ENOMEM;
> +
> + err = clk_get_by_index(dev, 0, &pdata->clk);
> + if (err)
> + return err;
> +
> + err = reset_get_by_index(dev, 0, &pdata->rst);
> + if (err)
> + return err;
> +
> + return 0;
> +}
> +
> +static const struct dm_rng_ops stm32_rng_ops = {
> + .read = stm32_rng_read,
> +};
> +
> +static const struct udevice_id stm32_rng_match[] = {
> + {
> + .compatible = "st,stm32-rng",
> + },
> + {},
> +};
> +
> +U_BOOT_DRIVER(stm32_rng) = {
> + .name = "stm32-rng",
> + .id = UCLASS_RNG,
> + .of_match = stm32_rng_match,
> + .ops = &stm32_rng_ops,
> + .probe = stm32_rng_probe,
> + .remove = stm32_rng_remove,
> + .platdata_auto_alloc_size = sizeof(struct stm32_rng_platdata),
> + .ofdata_to_platdata = stm32_rng_ofdata_to_platdata, };
> --
> 2.7.4