From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sughosh Ganu Date: Thu, 26 Dec 2019 22:55:03 +0530 Subject: [PATCH v5 3/8] stm32mp1: rng: Add a driver for random number generator(rng) device In-Reply-To: <1577381108-6320-1-git-send-email-sughosh.ganu@linaro.org> References: <1577381108-6320-1-git-send-email-sughosh.ganu@linaro.org> Message-ID: <1577381108-6320-4-git-send-email-sughosh.ganu@linaro.org> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de 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 Reviewed-by: Patrice Chotard Acked-by: Patrick Delaunay --- Changes since V4: * Return number of bytes read on a successful read, and a -ve value on error. drivers/rng/Kconfig | 7 ++ drivers/rng/Makefile | 1 + drivers/rng/stm32mp1_rng.c | 165 +++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 173 insertions(+) create mode 100644 drivers/rng/stm32mp1_rng.c diff --git a/drivers/rng/Kconfig b/drivers/rng/Kconfig index dd44cc0..c9c4751 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..56ad848 --- /dev/null +++ b/drivers/rng/stm32mp1_rng.c @@ -0,0 +1,165 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (c) 2019, Linaro Limited + */ + +#include +#include +#include +#include +#include + +#include +#include +#include + +#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, nbytes; + u32 sr, count, reg; + size_t increment; + struct stm32_rng_platdata *pdata = dev_get_platdata(dev); + + /* + * Only INT_MAX number of bytes can be returned. If more + * bytes need to be read, the caller must do it in a loop. + */ + if (len > INT_MAX) + len = INT_MAX; + + nbytes = len; + 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, ®, min(len, sizeof(u32))); + increment = min(len, sizeof(u32)); + data += increment; + len -= increment; + count--; + } + } + + return nbytes; +} + +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