[PATCH v3 2/2] hwrng: npcm: add NPCM RNG driver

Tomer Maimon tmaimon77 at gmail.com
Wed Oct 2 22:41:17 AEST 2019


HI all,

Appreciate a lot if one of the maintainers can take a look on HWRNG-NPCM
driver.

Thanks a lot!

Tomer


On Sun, 15 Sep 2019 at 09:26, Tomer Maimon <tmaimon77 at gmail.com> wrote:

> Hi Vinod,
>
> Thanks for your notification.
>
> NPCM Hardware RNG is true RNG.
>
> Tomer
>
> On Thu, 12 Sep 2019 at 19:47, Vinod Koul <vkoul at kernel.org> wrote:
>
>> On 12-09-19, 12:01, Tomer Maimon wrote:
>> > Add Nuvoton NPCM BMC Random Number Generator(RNG) driver.
>>
>> Is this a true RNG or a psedo RNG, in case of latter it should be added
>> in drivers/crypto/. See crypto_register_rng()
>>
>> >
>> > Signed-off-by: Tomer Maimon <tmaimon77 at gmail.com>
>> > ---
>> >  drivers/char/hw_random/Kconfig    |  13 +++
>> >  drivers/char/hw_random/Makefile   |   1 +
>> >  drivers/char/hw_random/npcm-rng.c | 186 ++++++++++++++++++++++++++++++
>> >  3 files changed, 200 insertions(+)
>> >  create mode 100644 drivers/char/hw_random/npcm-rng.c
>> >
>> > diff --git a/drivers/char/hw_random/Kconfig
>> b/drivers/char/hw_random/Kconfig
>> > index 59f25286befe..87a1c30e7958 100644
>> > --- a/drivers/char/hw_random/Kconfig
>> > +++ b/drivers/char/hw_random/Kconfig
>> > @@ -440,6 +440,19 @@ config HW_RANDOM_OPTEE
>> >
>> >         If unsure, say Y.
>> >
>> > +config HW_RANDOM_NPCM
>> > +     tristate "NPCM Random Number Generator support"
>> > +     depends on ARCH_NPCM || COMPILE_TEST
>> > +     default HW_RANDOM
>> > +     help
>> > +       This driver provides support for the Random Number
>> > +       Generator hardware available in Nuvoton NPCM SoCs.
>> > +
>> > +       To compile this driver as a module, choose M here: the
>> > +       module will be called npcm-rng.
>> > +
>> > +       If unsure, say Y.
>> > +
>> >  endif # HW_RANDOM
>> >
>> >  config UML_RANDOM
>> > diff --git a/drivers/char/hw_random/Makefile
>> b/drivers/char/hw_random/Makefile
>> > index 7c9ef4a7667f..17b6d4e6d591 100644
>> > --- a/drivers/char/hw_random/Makefile
>> > +++ b/drivers/char/hw_random/Makefile
>> > @@ -39,3 +39,4 @@ obj-$(CONFIG_HW_RANDOM_MTK) += mtk-rng.o
>> >  obj-$(CONFIG_HW_RANDOM_S390) += s390-trng.o
>> >  obj-$(CONFIG_HW_RANDOM_KEYSTONE) += ks-sa-rng.o
>> >  obj-$(CONFIG_HW_RANDOM_OPTEE) += optee-rng.o
>> > +obj-$(CONFIG_HW_RANDOM_NPCM) += npcm-rng.o
>> > diff --git a/drivers/char/hw_random/npcm-rng.c
>> b/drivers/char/hw_random/npcm-rng.c
>> > new file mode 100644
>> > index 000000000000..b7c8c7e13a49
>> > --- /dev/null
>> > +++ b/drivers/char/hw_random/npcm-rng.c
>> > @@ -0,0 +1,186 @@
>> > +// SPDX-License-Identifier: GPL-2.0
>> > +// Copyright (c) 2019 Nuvoton Technology corporation.
>> > +
>> > +#include <linux/kernel.h>
>> > +#include <linux/module.h>
>> > +#include <linux/io.h>
>> > +#include <linux/iopoll.h>
>> > +#include <linux/init.h>
>> > +#include <linux/random.h>
>> > +#include <linux/err.h>
>> > +#include <linux/platform_device.h>
>> > +#include <linux/hw_random.h>
>> > +#include <linux/delay.h>
>> > +#include <linux/of_irq.h>
>> > +#include <linux/pm_runtime.h>
>> > +
>> > +#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_USEC        20000
>> > +#define NPCM_RNG_POLL_USEC   1000
>> > +
>> > +#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);
>> > +
>> > +     writel(NPCM_RNG_CLK_SET_25MHZ | NPCM_RNG_ENABLE,
>> > +            priv->base + NPCM_RNGCS_REG);
>> > +
>> > +     return 0;
>> > +}
>> > +
>> > +static void npcm_rng_cleanup(struct hwrng *rng)
>> > +{
>> > +     struct npcm_rng *priv = to_npcm_rng(rng);
>> > +
>> > +     writel(NPCM_RNG_CLK_SET_25MHZ, priv->base + NPCM_RNGCS_REG);
>> > +}
>> > +
>> > +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;
>> > +     int ready;
>> > +
>> > +     pm_runtime_get_sync((struct device *)priv->rng.priv);
>> > +
>> > +     while (max >= sizeof(u32)) {
>> > +             if (wait) {
>> > +                     if (readl_poll_timeout(priv->base +
>> NPCM_RNGCS_REG,
>> > +                                            ready,
>> > +                                            ready &
>> NPCM_RNG_DATA_VALID,
>> > +                                            NPCM_RNG_POLL_USEC,
>> > +                                            NPCM_RNG_TIMEOUT_USEC))
>> > +                             break;
>> > +             } else {
>> > +                     if ((readl(priv->base + NPCM_RNGCS_REG) &
>> > +                         NPCM_RNG_DATA_VALID) == 0)
>> > +                             break;
>> > +             }
>> > +
>> > +             *(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;
>> > +     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);
>> > +
>> > +     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);
>> > +
>> > +#ifndef CONFIG_PM
>> > +     priv->rng.init = npcm_rng_init;
>> > +     priv->rng.cleanup = npcm_rng_cleanup;
>> > +#endif
>> > +     priv->rng.name = pdev->name;
>> > +     priv->rng.read = npcm_rng_read;
>> > +     priv->rng.priv = (unsigned long)&pdev->dev;
>> > +     priv->rng.quality = 1000;
>> > +
>> > +     writel(NPCM_RNG_M1ROSEL, priv->base + NPCM_RNGMODE_REG);
>> > +
>> > +     ret = devm_hwrng_register(&pdev->dev, &priv->rng);
>> > +     if (ret) {
>> > +             dev_err(&pdev->dev, "Failed to register rng device: %d\n",
>> > +                     ret);
>> > +             pm_runtime_disable(&pdev->dev);
>> > +             pm_runtime_set_suspended(&pdev->dev);
>> > +             return ret;
>> > +     }
>> > +
>> > +     return 0;
>> > +}
>> > +
>> > +static int npcm_rng_remove(struct platform_device *pdev)
>> > +{
>> > +     struct npcm_rng *priv = platform_get_drvdata(pdev);
>> > +
>> > +     devm_hwrng_unregister(&pdev->dev, &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,
>> > +             .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 <tomer.maimon at nuvoton.com>");
>> > +MODULE_LICENSE("GPL v2");
>> > --
>> > 2.18.0
>>
>> --
>> ~Vinod
>>
>
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