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219 lines
5.0 KiB
219 lines
5.0 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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* Copyright (c) 2015, Daniel Thompson |
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*/ |
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#include <linux/clk.h> |
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#include <linux/delay.h> |
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#include <linux/hw_random.h> |
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#include <linux/io.h> |
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#include <linux/iopoll.h> |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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#include <linux/of_address.h> |
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#include <linux/of_platform.h> |
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#include <linux/pm_runtime.h> |
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#include <linux/reset.h> |
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#include <linux/slab.h> |
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#define RNG_CR 0x00 |
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#define RNG_CR_RNGEN BIT(2) |
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#define RNG_CR_CED BIT(5) |
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#define RNG_SR 0x04 |
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#define RNG_SR_SEIS BIT(6) |
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#define RNG_SR_CEIS BIT(5) |
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#define RNG_SR_DRDY BIT(0) |
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#define RNG_DR 0x08 |
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struct stm32_rng_private { |
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struct hwrng rng; |
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void __iomem *base; |
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struct clk *clk; |
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struct reset_control *rst; |
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bool ced; |
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}; |
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static int stm32_rng_read(struct hwrng *rng, void *data, size_t max, bool wait) |
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{ |
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struct stm32_rng_private *priv = |
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container_of(rng, struct stm32_rng_private, rng); |
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u32 sr; |
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int retval = 0; |
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pm_runtime_get_sync((struct device *) priv->rng.priv); |
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while (max > sizeof(u32)) { |
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sr = readl_relaxed(priv->base + RNG_SR); |
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/* Manage timeout which is based on timer and take */ |
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/* care of initial delay time when enabling rng */ |
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if (!sr && wait) { |
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retval = readl_relaxed_poll_timeout_atomic(priv->base |
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+ RNG_SR, |
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sr, sr, |
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10, 50000); |
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if (retval) |
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dev_err((struct device *)priv->rng.priv, |
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"%s: timeout %x!\n", __func__, sr); |
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} |
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/* If error detected or data not ready... */ |
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if (sr != RNG_SR_DRDY) { |
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if (WARN_ONCE(sr & (RNG_SR_SEIS | RNG_SR_CEIS), |
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"bad RNG status - %x\n", sr)) |
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writel_relaxed(0, priv->base + RNG_SR); |
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break; |
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} |
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*(u32 *)data = readl_relaxed(priv->base + RNG_DR); |
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retval += sizeof(u32); |
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data += sizeof(u32); |
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max -= sizeof(u32); |
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} |
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pm_runtime_mark_last_busy((struct device *) priv->rng.priv); |
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pm_runtime_put_sync_autosuspend((struct device *) priv->rng.priv); |
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return retval || !wait ? retval : -EIO; |
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} |
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static int stm32_rng_init(struct hwrng *rng) |
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{ |
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struct stm32_rng_private *priv = |
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container_of(rng, struct stm32_rng_private, rng); |
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int err; |
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err = clk_prepare_enable(priv->clk); |
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if (err) |
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return err; |
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if (priv->ced) |
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writel_relaxed(RNG_CR_RNGEN, priv->base + RNG_CR); |
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else |
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writel_relaxed(RNG_CR_RNGEN | RNG_CR_CED, |
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priv->base + RNG_CR); |
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/* clear error indicators */ |
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writel_relaxed(0, priv->base + RNG_SR); |
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return 0; |
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} |
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static void stm32_rng_cleanup(struct hwrng *rng) |
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{ |
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struct stm32_rng_private *priv = |
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container_of(rng, struct stm32_rng_private, rng); |
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writel_relaxed(0, priv->base + RNG_CR); |
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clk_disable_unprepare(priv->clk); |
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} |
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static int stm32_rng_probe(struct platform_device *ofdev) |
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{ |
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struct device *dev = &ofdev->dev; |
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struct device_node *np = ofdev->dev.of_node; |
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struct stm32_rng_private *priv; |
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struct resource res; |
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int err; |
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priv = devm_kzalloc(dev, sizeof(struct stm32_rng_private), GFP_KERNEL); |
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if (!priv) |
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return -ENOMEM; |
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err = of_address_to_resource(np, 0, &res); |
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if (err) |
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return err; |
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priv->base = devm_ioremap_resource(dev, &res); |
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if (IS_ERR(priv->base)) |
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return PTR_ERR(priv->base); |
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priv->clk = devm_clk_get(&ofdev->dev, NULL); |
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if (IS_ERR(priv->clk)) |
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return PTR_ERR(priv->clk); |
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priv->rst = devm_reset_control_get(&ofdev->dev, NULL); |
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if (!IS_ERR(priv->rst)) { |
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reset_control_assert(priv->rst); |
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udelay(2); |
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reset_control_deassert(priv->rst); |
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} |
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priv->ced = of_property_read_bool(np, "clock-error-detect"); |
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dev_set_drvdata(dev, priv); |
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priv->rng.name = dev_driver_string(dev); |
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#ifndef CONFIG_PM |
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priv->rng.init = stm32_rng_init; |
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priv->rng.cleanup = stm32_rng_cleanup; |
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#endif |
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priv->rng.read = stm32_rng_read; |
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priv->rng.priv = (unsigned long) dev; |
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priv->rng.quality = 900; |
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pm_runtime_set_autosuspend_delay(dev, 100); |
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pm_runtime_use_autosuspend(dev); |
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pm_runtime_enable(dev); |
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return devm_hwrng_register(dev, &priv->rng); |
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} |
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static int stm32_rng_remove(struct platform_device *ofdev) |
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{ |
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pm_runtime_disable(&ofdev->dev); |
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return 0; |
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} |
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#ifdef CONFIG_PM |
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static int stm32_rng_runtime_suspend(struct device *dev) |
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{ |
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struct stm32_rng_private *priv = dev_get_drvdata(dev); |
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stm32_rng_cleanup(&priv->rng); |
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return 0; |
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} |
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static int stm32_rng_runtime_resume(struct device *dev) |
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{ |
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struct stm32_rng_private *priv = dev_get_drvdata(dev); |
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return stm32_rng_init(&priv->rng); |
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} |
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#endif |
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static const struct dev_pm_ops stm32_rng_pm_ops = { |
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SET_RUNTIME_PM_OPS(stm32_rng_runtime_suspend, |
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stm32_rng_runtime_resume, NULL) |
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SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, |
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pm_runtime_force_resume) |
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}; |
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static const struct of_device_id stm32_rng_match[] = { |
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{ |
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.compatible = "st,stm32-rng", |
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}, |
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{}, |
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}; |
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MODULE_DEVICE_TABLE(of, stm32_rng_match); |
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static struct platform_driver stm32_rng_driver = { |
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.driver = { |
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.name = "stm32-rng", |
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.pm = &stm32_rng_pm_ops, |
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.of_match_table = stm32_rng_match, |
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}, |
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.probe = stm32_rng_probe, |
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.remove = stm32_rng_remove, |
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}; |
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module_platform_driver(stm32_rng_driver); |
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MODULE_LICENSE("GPL"); |
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MODULE_AUTHOR("Daniel Thompson <[email protected]>"); |
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MODULE_DESCRIPTION("STMicroelectronics STM32 RNG device driver");
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