The RNG present on STM32MP13x platforms introduces a customizable configuration and the conditional reset. STM32 RNG configuration should best fit the requirements of the platform. Therefore, put a platform-specific RNG configuration field in the platform data. Default RNG configuration for STM32MP13 is the NIST certified configuration [1]. While there, fix and the RNG init sequence to support all RNG versions. [1] https://csrc.nist.gov/projects/cryptographic-module-validation-program/entropy-validations/certificate/53 Signed-off-by: Gatien Chevallier <gatien.chevallier@xxxxxxxxxxx> --- drivers/char/hw_random/stm32-rng.c | 222 ++++++++++++++++++++--------- 1 file changed, 158 insertions(+), 64 deletions(-) diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/stm32-rng.c index d64d25d0fee8..54bd5807bbac 100644 --- a/drivers/char/hw_random/stm32-rng.c +++ b/drivers/char/hw_random/stm32-rng.c @@ -17,22 +17,43 @@ #include <linux/reset.h> #include <linux/slab.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_DRDY BIT(0) - -#define RNG_DR 0x08 +#define RNG_CR 0x00 +#define RNG_CR_RNGEN BIT(2) +#define RNG_CR_CED BIT(5) +#define RNG_CR_CONFIG1 GENMASK(11, 8) +#define RNG_CR_NISTC BIT(12) +#define RNG_CR_CONFIG2 GENMASK(15, 13) +#define RNG_CR_CONFIG3 GENMASK(25, 20) +#define RNG_CR_CONDRST BIT(30) +#define RNG_CR_CONFLOCK BIT(31) +#define RNG_CR_ENTROPY_SRC_MASK (RNG_CR_CONFIG1 | RNG_CR_NISTC | RNG_CR_CONFIG2 | RNG_CR_CONFIG3) +#define RNG_CR_CONFIG_MASK (RNG_CR_ENTROPY_SRC_MASK | RNG_CR_CED) + +#define RNG_SR 0x04 +#define RNG_SR_SEIS BIT(6) +#define RNG_SR_CEIS BIT(5) +#define RNG_SR_DRDY BIT(0) + +#define RNG_DR 0x08 + +#define RNG_NSCR 0x0C +#define RNG_NSCR_MASK GENMASK(17, 0) + +#define RNG_HTCR 0x10 + +struct stm32_rng_data { + u32 cr; + u32 nscr; + u32 htcr; + bool has_cond_reset; +}; struct stm32_rng_private { struct hwrng rng; void __iomem *base; struct clk *clk; struct reset_control *rst; + const struct stm32_rng_data *data; bool ced; }; @@ -87,32 +108,145 @@ static int stm32_rng_init(struct hwrng *rng) struct stm32_rng_private *priv = container_of(rng, struct stm32_rng_private, rng); int err; + u32 reg; err = clk_prepare_enable(priv->clk); if (err) return err; - if (priv->ced) - writel_relaxed(RNG_CR_RNGEN, priv->base + RNG_CR); - else - writel_relaxed(RNG_CR_RNGEN | RNG_CR_CED, - priv->base + RNG_CR); - /* clear error indicators */ writel_relaxed(0, priv->base + RNG_SR); + reg = readl_relaxed(priv->base + RNG_CR); + + /* + * Keep default RNG configuration if none was specified. + * 0 is an invalid value as it disables all entropy sources. + */ + if (priv->data->has_cond_reset && priv->data->cr) { + reg &= ~RNG_CR_CONFIG_MASK; + reg |= RNG_CR_CONDRST | (priv->data->cr & RNG_CR_ENTROPY_SRC_MASK); + if (priv->ced) + reg &= ~RNG_CR_CED; + else + reg |= RNG_CR_CED; + writel_relaxed(reg, priv->base + RNG_CR); + + /* Health tests and noise control registers */ + writel_relaxed(priv->data->htcr, priv->base + RNG_HTCR); + writel_relaxed(priv->data->nscr & RNG_NSCR_MASK, priv->base + RNG_NSCR); + + reg &= ~RNG_CR_CONDRST; + reg |= RNG_CR_RNGEN; + writel_relaxed(reg, priv->base + RNG_CR); + + err = readl_relaxed_poll_timeout_atomic(priv->base + RNG_CR, reg, + (!(reg & RNG_CR_CONDRST)), + 10, 50000); + if (err) { + dev_err((struct device *)priv->rng.priv, + "%s: timeout %x!\n", __func__, reg); + return -EINVAL; + } + } else { + /* Handle all RNG versions by checking if conditional reset should be set */ + if (priv->data->has_cond_reset) + reg |= RNG_CR_CONDRST; + + if (priv->ced) + reg &= ~RNG_CR_CED; + else + reg |= RNG_CR_CED; + + writel_relaxed(reg, priv->base + RNG_CR); + + if (priv->data->has_cond_reset) + reg &= ~RNG_CR_CONDRST; + + reg |= RNG_CR_RNGEN; + + writel_relaxed(reg, priv->base + RNG_CR); + } + + err = readl_relaxed_poll_timeout_atomic(priv->base + RNG_SR, reg, + reg & RNG_SR_DRDY, + 10, 100000); + if (err | (reg & ~RNG_SR_DRDY)) { + clk_disable_unprepare(priv->clk); + dev_err((struct device *)priv->rng.priv, + "%s: timeout:%x SR: %x!\n", __func__, err, reg); + return -EINVAL; + } + return 0; } -static void stm32_rng_cleanup(struct hwrng *rng) +static int stm32_rng_remove(struct platform_device *ofdev) { - struct stm32_rng_private *priv = - container_of(rng, struct stm32_rng_private, rng); + pm_runtime_disable(&ofdev->dev); + + return 0; +} + +#ifdef CONFIG_PM +static int stm32_rng_runtime_suspend(struct device *dev) +{ + u32 reg; + struct stm32_rng_private *priv = dev_get_drvdata(dev); - writel_relaxed(0, priv->base + RNG_CR); + reg = readl_relaxed(priv->base + RNG_CR); + reg &= ~RNG_CR_RNGEN; + writel_relaxed(reg, priv->base + RNG_CR); clk_disable_unprepare(priv->clk); + + return 0; } +static int stm32_rng_runtime_resume(struct device *dev) +{ + u32 reg; + struct stm32_rng_private *priv = dev_get_drvdata(dev); + + clk_prepare_enable(priv->clk); + reg = readl_relaxed(priv->base + RNG_CR); + reg |= RNG_CR_RNGEN; + writel_relaxed(reg, priv->base + RNG_CR); + + return 0; +} +#endif + +static const struct dev_pm_ops stm32_rng_pm_ops = { + SET_RUNTIME_PM_OPS(stm32_rng_runtime_suspend, + stm32_rng_runtime_resume, NULL) + SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, + pm_runtime_force_resume) +}; + +static const struct stm32_rng_data stm32mp13_rng_data = { + .has_cond_reset = true, + .cr = 0x00F00D00, + .nscr = 0x2B5BB, + .htcr = 0x969D, +}; + +static const struct stm32_rng_data stm32_rng_data = { + .has_cond_reset = false, +}; + +static const struct of_device_id stm32_rng_match[] = { + { + .compatible = "st,stm32mp13-rng", + .data = &stm32mp13_rng_data, + }, + { + .compatible = "st,stm32-rng", + .data = &stm32_rng_data, + }, + {}, +}; +MODULE_DEVICE_TABLE(of, stm32_rng_match); + static int stm32_rng_probe(struct platform_device *ofdev) { struct device *dev = &ofdev->dev; @@ -141,13 +275,14 @@ static int stm32_rng_probe(struct platform_device *ofdev) priv->ced = of_property_read_bool(np, "clock-error-detect"); + priv->data = of_device_get_match_data(dev); + if (!priv->data) + return -ENODEV; + dev_set_drvdata(dev, priv); priv->rng.name = dev_driver_string(dev); -#ifndef CONFIG_PM priv->rng.init = stm32_rng_init; - priv->rng.cleanup = stm32_rng_cleanup; -#endif priv->rng.read = stm32_rng_read; priv->rng.priv = (unsigned long) dev; priv->rng.quality = 900; @@ -159,47 +294,6 @@ static int stm32_rng_probe(struct platform_device *ofdev) return devm_hwrng_register(dev, &priv->rng); } -static int stm32_rng_remove(struct platform_device *ofdev) -{ - pm_runtime_disable(&ofdev->dev); - - return 0; -} - -#ifdef CONFIG_PM -static int stm32_rng_runtime_suspend(struct device *dev) -{ - struct stm32_rng_private *priv = dev_get_drvdata(dev); - - stm32_rng_cleanup(&priv->rng); - - return 0; -} - -static int stm32_rng_runtime_resume(struct device *dev) -{ - struct stm32_rng_private *priv = dev_get_drvdata(dev); - - return stm32_rng_init(&priv->rng); -} -#endif - -static const struct dev_pm_ops stm32_rng_pm_ops = { - SET_RUNTIME_PM_OPS(stm32_rng_runtime_suspend, - stm32_rng_runtime_resume, NULL) - SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, - pm_runtime_force_resume) -}; - - -static const struct of_device_id stm32_rng_match[] = { - { - .compatible = "st,stm32-rng", - }, - {}, -}; -MODULE_DEVICE_TABLE(of, stm32_rng_match); - static struct platform_driver stm32_rng_driver = { .driver = { .name = "stm32-rng", -- 2.25.1
