Hi Daniel, appreciate your comments and sorry for the late reply On Thu, 29 Aug 2019 at 13:47, Daniel Thompson wrote: > On Wed, Aug 28, 2019 at 07:26:17PM +0300, Tomer Maimon wrote: > > Add Nuvoton NPCM BMC Random Number Generator(RNG) driver. > > > > Signed-off-by: Tomer Maimon > > --- > > drivers/char/hw_random/Kconfig | 13 ++ > > drivers/char/hw_random/Makefile | 1 + > > drivers/char/hw_random/npcm-rng.c | 207 ++++++++++++++++++++++++++++++ > > 3 files changed, 221 insertions(+) > > create mode 100644 drivers/char/hw_random/npcm-rng.c > > > > diff --git a/drivers/char/hw_random/npcm-rng.c > b/drivers/char/hw_random/npcm-rng.c > > new file mode 100644 > > index 000000000000..5b4b1b6cb362 > > --- /dev/null > > +++ b/drivers/char/hw_random/npcm-rng.c > > @@ -0,0 +1,207 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +// Copyright (c) 2019 Nuvoton Technology corporation. > > + > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > +#include > > + > > +#define NPCM_RNGCS_REG 0x00 /* Control and status > register */ > > +#define NPCM_RNGD_REG 0x04 /* Data register */ > > +#define NPCM_RNGMODE_REG 0x08 /* Mode register */ > > + > > +#define NPCM_RNG_CLK_SET_25MHZ GENMASK(4, 3) /* 20-25 MHz */ > > +#define NPCM_RNG_DATA_VALID BIT(1) > > +#define NPCM_RNG_ENABLE BIT(0) > > +#define NPCM_RNG_M1ROSEL BIT(1) > > + > > +#define NPCM_RNG_TIMEOUT_POLL 20 > > Might be better to define this in real-world units (such as > milliseconds) since the timeout is effectively the longest time the > hardware can take to generate 4 bytes. > > > + > > +#define to_npcm_rng(p) container_of(p, struct npcm_rng, rng) > > + > > +struct npcm_rng { > > + void __iomem *base; > > + struct hwrng rng; > > +}; > > + > > +static int npcm_rng_init(struct hwrng *rng) > > +{ > > + struct npcm_rng *priv = to_npcm_rng(rng); > > + u32 val; > > + > > + val = readl(priv->base + NPCM_RNGCS_REG); > > + val |= NPCM_RNG_ENABLE; > > + writel(val, priv->base + NPCM_RNGCS_REG); > > + > > + return 0; > > +} > > + > > +static void npcm_rng_cleanup(struct hwrng *rng) > > +{ > > + struct npcm_rng *priv = to_npcm_rng(rng); > > + u32 val; > > + > > + val = readl(priv->base + NPCM_RNGCS_REG); > > + val &= ~NPCM_RNG_ENABLE; > > + writel(val, priv->base + NPCM_RNGCS_REG); > > +} > > + > > +static bool npcm_rng_wait_ready(struct hwrng *rng, bool wait) > > +{ > > + struct npcm_rng *priv = to_npcm_rng(rng); > > + int timeout_cnt = 0; > > + int ready; > > + > > + ready = readl(priv->base + NPCM_RNGCS_REG) & NPCM_RNG_DATA_VALID; > > + while ((ready == 0) && (timeout_cnt < NPCM_RNG_TIMEOUT_POLL)) { > > + usleep_range(500, 1000); > > + ready = readl(priv->base + NPCM_RNGCS_REG) & > > + NPCM_RNG_DATA_VALID; > > + timeout_cnt++; > > + } > > + > > + return !!ready; > > +} > > This looks like an open-coded version of readl_poll_timeout()... better > to use the library function. > > Also the sleep looks a bit long to me. What is the generation rate of > the peripheral? Most RNG drivers have short intervals between data > generation so they use delays rather than sleeps (a.k.a. > readl_poll_timeout_atomic() ). > > the HWRNG generate byte of random data in a few milliseconds so it is better to use the sleep command. > > > + > > +static int npcm_rng_read(struct hwrng *rng, void *buf, size_t max, bool > wait) > > +{ > > + struct npcm_rng *priv = to_npcm_rng(rng); > > + int retval = 0; > > + > > + pm_runtime_get_sync((struct device *)priv->rng.priv); > > + > > + while (max >= sizeof(u32)) { > > + if (!npcm_rng_wait_ready(rng, wait)) > > + break; > > The code as currently written does not honour the wait parameter (e.g. > it sleeps even when wait is false). > > > > + > > + *(u32 *)buf = readl(priv->base + NPCM_RNGD_REG); > > + retval += sizeof(u32); > > + buf += 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 npcm_rng_probe(struct platform_device *pdev) > > +{ > > + struct npcm_rng *priv; > > + struct resource *res; > > + u32 quality; > > + int ret; > > + > > + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); > > + if (!priv) > > + return -ENOMEM; > > + > > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); > > + priv->base = devm_ioremap_resource(&pdev->dev, res); > > + if (IS_ERR(priv->base)) > > + return PTR_ERR(priv->base); > > + > > + priv->rng.name = pdev->name; > > +#ifndef CONFIG_PM > > + priv->rng.init = npcm_rng_init; > > + priv->rng.cleanup = npcm_rng_cleanup; > > +#endif > > + priv->rng.read = npcm_rng_read; > > + priv->rng.priv = (unsigned long)&pdev->dev; > > + if (of_property_read_u32(pdev->dev.of_node, "quality", &quality)) > > + priv->rng.quality = 1000; > > + else > > + priv->rng.quality = quality; > > + > > + writel(NPCM_RNG_M1ROSEL, priv->base + NPCM_RNGMODE_REG); > > +#ifndef CONFIG_PM > > + writel(NPCM_RNG_CLK_SET_25MHZ, priv->base + NPCM_RNGCS_REG); > > +#else > > + writel(NPCM_RNG_CLK_SET_25MHZ | NPCM_RNG_ENABLE, > > + priv->base + NPCM_RNGCS_REG); > > +#endif > > If this initialization was moved to npcm_rng_init() then there would be > no need for the additional ifdefing. It would also get rid of the > (potentially slow) readl calls on the PM wakeup path. > But when the Kernel have PM configuration than the priv->rng.init is not set and *add_early_randomness* function is called. for the *add_early_randomness* success the hwrng need to enabled in the probe. I will remove the ifdef and add local variable instead (as Milton Miller suggested) > > + > > + ret = devm_hwrng_register(&pdev->dev, &priv->rng); > > + if (ret) { > > + dev_err(&pdev->dev, "Failed to register rng device: %d\n", > > + ret); > > + return ret; > > + } > > + > > + dev_set_drvdata(&pdev->dev, priv); > > + pm_runtime_set_autosuspend_delay(&pdev->dev, 100); > > + pm_runtime_use_autosuspend(&pdev->dev); > > + pm_runtime_enable(&pdev->dev); > > + > > + dev_info(&pdev->dev, "Random Number Generator Probed\n"); > > Does the user need to know this every time we boot? There are lots of > debug tools we can bring to bear if they are worried the device > isn't probing. > > > Daniel. > > > > + > > + return 0; > > +} > > + > > +static int npcm_rng_remove(struct platform_device *pdev) > > +{ > > + struct npcm_rng *priv = platform_get_drvdata(pdev); > > + > > + hwrng_unregister(&priv->rng); > > + pm_runtime_disable(&pdev->dev); > > + pm_runtime_set_suspended(&pdev->dev); > > + > > + return 0; > > +} > > + > > +#ifdef CONFIG_PM > > +static int npcm_rng_runtime_suspend(struct device *dev) > > +{ > > + struct npcm_rng *priv = dev_get_drvdata(dev); > > + > > + npcm_rng_cleanup(&priv->rng); > > + > > + return 0; > > +} > > + > > +static int npcm_rng_runtime_resume(struct device *dev) > > +{ > > + struct npcm_rng *priv = dev_get_drvdata(dev); > > + > > + return npcm_rng_init(&priv->rng); > > +} > > +#endif > > + > > +static const struct dev_pm_ops npcm_rng_pm_ops = { > > + SET_RUNTIME_PM_OPS(npcm_rng_runtime_suspend, > > + npcm_rng_runtime_resume, NULL) > > + SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend, > > + pm_runtime_force_resume) > > +}; > > + > > +static const struct of_device_id rng_dt_id[] = { > > + { .compatible = "nuvoton,npcm750-rng", }, > > + {}, > > +}; > > +MODULE_DEVICE_TABLE(of, rng_dt_id); > > + > > +static struct platform_driver npcm_rng_driver = { > > + .driver = { > > + .name = "npcm-rng", > > + .pm = &npcm_rng_pm_ops, > > + .owner = THIS_MODULE, > > + .of_match_table = of_match_ptr(rng_dt_id), > > + }, > > + .probe = npcm_rng_probe, > > + .remove = npcm_rng_remove, > > +}; > > + > > +module_platform_driver(npcm_rng_driver); > > + > > +MODULE_DESCRIPTION("Nuvoton NPCM Random Number Generator Driver"); > > +MODULE_AUTHOR("Tomer Maimon "); > > +MODULE_LICENSE("GPL v2"); > > -- > > 2.18.0 > > > Thanks a lot, Tomer