| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* |
| * Copyright (c) 2015, Daniel Thompson |
| */ |
| |
| #include <linux/clk.h> |
| #include <linux/delay.h> |
| #include <linux/hw_random.h> |
| #include <linux/io.h> |
| #include <linux/iopoll.h> |
| #include <linux/kernel.h> |
| #include <linux/module.h> |
| #include <linux/of_address.h> |
| #include <linux/of_platform.h> |
| #include <linux/pm_runtime.h> |
| #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 |
| |
| struct stm32_rng_private { |
| struct hwrng rng; |
| void __iomem *base; |
| struct clk *clk; |
| struct reset_control *rst; |
| bool ced; |
| }; |
| |
| static int stm32_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) |
| { |
| struct stm32_rng_private *priv = |
| container_of(rng, struct stm32_rng_private, rng); |
| u32 sr; |
| int retval = 0; |
| |
| pm_runtime_get_sync((struct device *) priv->rng.priv); |
| |
| while (max >= sizeof(u32)) { |
| sr = readl_relaxed(priv->base + RNG_SR); |
| /* Manage timeout which is based on timer and take */ |
| /* care of initial delay time when enabling rng */ |
| if (!sr && wait) { |
| int err; |
| |
| err = readl_relaxed_poll_timeout_atomic(priv->base |
| + RNG_SR, |
| sr, sr, |
| 10, 50000); |
| if (err) |
| dev_err((struct device *)priv->rng.priv, |
| "%s: timeout %x!\n", __func__, sr); |
| } |
| |
| /* If error detected or data not ready... */ |
| if (sr != RNG_SR_DRDY) { |
| if (WARN_ONCE(sr & (RNG_SR_SEIS | RNG_SR_CEIS), |
| "bad RNG status - %x\n", sr)) |
| writel_relaxed(0, priv->base + RNG_SR); |
| break; |
| } |
| |
| *(u32 *)data = readl_relaxed(priv->base + RNG_DR); |
| |
| retval += sizeof(u32); |
| data += sizeof(u32); |
| max -= sizeof(u32); |
| } |
| |
| pm_runtime_mark_last_busy((struct device *) priv->rng.priv); |
| pm_runtime_put_sync_autosuspend((struct device *) priv->rng.priv); |
| |
| return retval || !wait ? retval : -EIO; |
| } |
| |
| static int stm32_rng_init(struct hwrng *rng) |
| { |
| struct stm32_rng_private *priv = |
| container_of(rng, struct stm32_rng_private, rng); |
| int err; |
| |
| 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); |
| |
| return 0; |
| } |
| |
| static void stm32_rng_cleanup(struct hwrng *rng) |
| { |
| struct stm32_rng_private *priv = |
| container_of(rng, struct stm32_rng_private, rng); |
| |
| writel_relaxed(0, priv->base + RNG_CR); |
| clk_disable_unprepare(priv->clk); |
| } |
| |
| static int stm32_rng_probe(struct platform_device *ofdev) |
| { |
| struct device *dev = &ofdev->dev; |
| struct device_node *np = ofdev->dev.of_node; |
| struct stm32_rng_private *priv; |
| struct resource res; |
| int err; |
| |
| priv = devm_kzalloc(dev, sizeof(struct stm32_rng_private), GFP_KERNEL); |
| if (!priv) |
| return -ENOMEM; |
| |
| err = of_address_to_resource(np, 0, &res); |
| if (err) |
| return err; |
| |
| priv->base = devm_ioremap_resource(dev, &res); |
| if (IS_ERR(priv->base)) |
| return PTR_ERR(priv->base); |
| |
| priv->clk = devm_clk_get(&ofdev->dev, NULL); |
| if (IS_ERR(priv->clk)) |
| return PTR_ERR(priv->clk); |
| |
| priv->rst = devm_reset_control_get(&ofdev->dev, NULL); |
| if (!IS_ERR(priv->rst)) { |
| reset_control_assert(priv->rst); |
| udelay(2); |
| reset_control_deassert(priv->rst); |
| } |
| |
| priv->ced = of_property_read_bool(np, "clock-error-detect"); |
| |
| 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; |
| |
| pm_runtime_set_autosuspend_delay(dev, 100); |
| pm_runtime_use_autosuspend(dev); |
| pm_runtime_enable(dev); |
| |
| 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", |
| .pm = &stm32_rng_pm_ops, |
| .of_match_table = stm32_rng_match, |
| }, |
| .probe = stm32_rng_probe, |
| .remove = stm32_rng_remove, |
| }; |
| |
| module_platform_driver(stm32_rng_driver); |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Daniel Thompson <daniel.thompson@linaro.org>"); |
| MODULE_DESCRIPTION("STMicroelectronics STM32 RNG device driver"); |