Implement stm32_rng_suspend()/stm32_rng_resume() low-power APIs called when the hardware block context will be lost. There is no need to save the RNG_CR register in stm32_rng_runtime_suspend() as the context is not lost. Therefore, only enable/disable the RNG in the runtime sequences. Signed-off-by: Gatien Chevallier <gatien.chevallier@xxxxxxxxxxx> --- drivers/char/hw_random/stm32-rng.c | 100 +++++++++++++++++++++++++++-- 1 file changed, 93 insertions(+), 7 deletions(-) diff --git a/drivers/char/hw_random/stm32-rng.c b/drivers/char/hw_random/stm32-rng.c index 0243b889ac54..3ac6712324c7 100644 --- a/drivers/char/hw_random/stm32-rng.c +++ b/drivers/char/hw_random/stm32-rng.c @@ -55,11 +55,25 @@ struct stm32_rng_data { bool has_cond_reset; }; +/** + * struct stm32_rng_config - RNG configuration data + * + * @cr: RNG configuration. 0 means default hardware RNG configuration + * @nscr: Noise sources control configuration. + * @htcr: Health tests configuration. + */ +struct stm32_rng_config { + u32 cr; + u32 nscr; + u32 htcr; +}; + struct stm32_rng_private { struct hwrng rng; void __iomem *base; struct clk *clk; struct reset_control *rst; + struct stm32_rng_config pm_conf; const struct stm32_rng_data *data; bool ced; bool lock_conf; @@ -355,11 +369,10 @@ static int stm32_rng_remove(struct platform_device *ofdev) 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); + u32 reg; reg = readl_relaxed(priv->base + RNG_CR); reg &= ~RNG_CR_RNGEN; @@ -369,25 +382,98 @@ static int stm32_rng_runtime_suspend(struct device *dev) return 0; } +static int __maybe_unused stm32_rng_suspend(struct device *dev) +{ + struct stm32_rng_private *priv = dev_get_drvdata(dev); + + if (priv->data->has_cond_reset) { + priv->pm_conf.nscr = readl_relaxed(priv->base + RNG_NSCR); + priv->pm_conf.htcr = readl_relaxed(priv->base + RNG_HTCR); + } + + /* Do not save that RNG is enabled as it will be handled at resume */ + priv->pm_conf.cr = readl_relaxed(priv->base + RNG_CR) & ~RNG_CR_RNGEN; + + writel_relaxed(priv->pm_conf.cr, 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); + int err; + u32 reg; + + err = clk_prepare_enable(priv->clk); + if (err) + return err; + + /* Clean error indications */ + writel_relaxed(0, priv->base + RNG_SR); - 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 int __maybe_unused stm32_rng_resume(struct device *dev) +{ + struct stm32_rng_private *priv = dev_get_drvdata(dev); + int err; + u32 reg; + + err = clk_prepare_enable(priv->clk); + if (err) + return err; + + /* Clean error indications */ + writel_relaxed(0, priv->base + RNG_SR); + + if (priv->data->has_cond_reset) { + /* + * Correct configuration in bits [29:4] must be set in the same + * access that set RNG_CR_CONDRST bit. Else config setting is + * not taken into account. CONFIGLOCK bit must also be unset but + * it is not handled at the moment. + */ + writel_relaxed(priv->pm_conf.cr | RNG_CR_CONDRST, priv->base + RNG_CR); + + writel_relaxed(priv->pm_conf.nscr, priv->base + RNG_NSCR); + writel_relaxed(priv->pm_conf.htcr, priv->base + RNG_HTCR); + + reg = readl_relaxed(priv->base + RNG_CR); + reg |= RNG_CR_RNGEN; + reg &= ~RNG_CR_CONDRST; + writel_relaxed(reg, priv->base + RNG_CR); + + err = readl_relaxed_poll_timeout_atomic(priv->base + RNG_CR, reg, + reg & ~RNG_CR_CONDRST, 10, 100000); + + if (err) { + clk_disable_unprepare(priv->clk); + dev_err((struct device *)priv->rng.priv, + "%s: timeout:%x CR: %x!\n", __func__, err, reg); + return -EINVAL; + } + } else { + reg = priv->pm_conf.cr; + reg |= RNG_CR_RNGEN; + writel_relaxed(reg, priv->base + RNG_CR); + } + + return 0; +} 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) + SET_SYSTEM_SLEEP_PM_OPS(stm32_rng_suspend, + stm32_rng_resume) }; static const struct stm32_rng_data stm32mp13_rng_data = { -- 2.25.1