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    SubjectRe: [PATCH v2 5/7] hwrng: st: Add support for ST's HW Random Number Generator
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    On 17 September 2015 at 14:45, Lee Jones <lee.jones@linaro.org> wrote:
    > Signed-off-by: Pankaj Dev <pankaj.dev@st.com>
    > Signed-off-by: Lee Jones <lee.jones@linaro.org>

    Comments addressed, Also LGTM.
    Acked-by: Kieran Bingham <kieranbingham@gmail.com>


    > ---
    > drivers/char/hw_random/Kconfig | 10 +++
    > drivers/char/hw_random/Makefile | 1 +
    > drivers/char/hw_random/st-rng.c | 144 ++++++++++++++++++++++++++++++++++++++++
    > 3 files changed, 155 insertions(+)
    > create mode 100644 drivers/char/hw_random/st-rng.c
    >
    > diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
    > index 8998108..ba5406b 100644
    > --- a/drivers/char/hw_random/Kconfig
    > +++ b/drivers/char/hw_random/Kconfig
    > @@ -346,6 +346,16 @@ config HW_RANDOM_MSM
    >
    > If unsure, say Y.
    >
    > +config HW_RANDOM_ST
    > + tristate "ST Microelectronics HW Random Number Generator support"
    > + depends on HW_RANDOM && ARCH_STI
    > + ---help---
    > + This driver provides kernel-side support for the Random Number
    > + Generator hardware found on STi series of SoCs.
    > +
    > + To compile this driver as a module, choose M here: the
    > + module will be called st-rng.
    > +
    > config HW_RANDOM_XGENE
    > tristate "APM X-Gene True Random Number Generator (TRNG) support"
    > depends on HW_RANDOM && ARCH_XGENE
    > diff --git a/drivers/char/hw_random/Makefile b/drivers/char/hw_random/Makefile
    > index 055bb01..8bcfb45 100644
    > --- a/drivers/char/hw_random/Makefile
    > +++ b/drivers/char/hw_random/Makefile
    > @@ -30,4 +30,5 @@ obj-$(CONFIG_HW_RANDOM_TPM) += tpm-rng.o
    > obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
    > obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o
    > obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
    > +obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
    > obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
    > diff --git a/drivers/char/hw_random/st-rng.c b/drivers/char/hw_random/st-rng.c
    > new file mode 100644
    > index 0000000..8c8a435
    > --- /dev/null
    > +++ b/drivers/char/hw_random/st-rng.c
    > @@ -0,0 +1,144 @@
    > +/*
    > + * ST Random Number Generator Driver ST's Platforms
    > + *
    > + * Author: Pankaj Dev: <pankaj.dev@st.com>
    > + * Lee Jones <lee.jones@linaro.org>
    > + *
    > + * Copyright (C) 2015 STMicroelectronics (R&D) Limited
    > + *
    > + * This program is free software; you can redistribute it and/or modify
    > + * it under the terms of the GNU General Public License version 2 as
    > + * published by the Free Software Foundation.
    > + */
    > +
    > +#include <linux/clk.h>
    > +#include <linux/delay.h>
    > +#include <linux/hw_random.h>
    > +#include <linux/io.h>
    > +#include <linux/module.h>
    > +#include <linux/of.h>
    > +#include <linux/platform_device.h>
    > +#include <linux/slab.h>
    > +
    > +/* Registers */
    > +#define ST_RNG_STATUS_REG 0x20
    > +#define ST_RNG_DATA_REG 0x24
    > +
    > +/* Registers fields */
    > +#define ST_RNG_STATUS_BAD_SEQUENCE BIT(0)
    > +#define ST_RNG_STATUS_BAD_ALTERNANCE BIT(1)
    > +#define ST_RNG_STATUS_FIFO_FULL BIT(5)
    > +
    > +#define ST_RNG_FIFO_SIZE 8
    > +#define ST_RNG_SAMPLE_SIZE 2 /* 2 Byte (16bit) samples */
    > +
    > +/* Samples are available every 0.667us, which we round to 1us */
    > +#define ST_RNG_FILL_FIFO_TIMEOUT (1 * (ST_RNG_FIFO_SIZE / ST_RNG_SAMPLE_SIZE))
    > +
    > +struct st_rng_data {
    > + void __iomem *base;
    > + struct clk *clk;
    > + struct hwrng ops;
    > +};
    > +
    > +static int st_rng_read(struct hwrng *rng, void *data, size_t max, bool wait)
    > +{
    > + struct st_rng_data *ddata = (struct st_rng_data *)rng->priv;
    > + u32 status;
    > + int i;
    > +
    > + if (max < sizeof(u16))
    > + return -EINVAL;
    > +
    > + /* Wait until FIFO is full - max 4uS*/
    > + for (i = 0; i < ST_RNG_FILL_FIFO_TIMEOUT; i++) {
    > + status = readl_relaxed(ddata->base + ST_RNG_STATUS_REG);
    > + if (status & ST_RNG_STATUS_FIFO_FULL)
    > + break;
    > + udelay(1);
    > + }
    > +
    > + if (i == ST_RNG_FILL_FIFO_TIMEOUT)
    > + return 0;
    > +
    > + for (i = 0; i < ST_RNG_FIFO_SIZE && i < max; i += 2)
    > + *(u16 *)(data + i) =
    > + readl_relaxed(ddata->base + ST_RNG_DATA_REG);
    > +
    > + return i; /* No of bytes read */
    > +}
    > +
    > +static int st_rng_probe(struct platform_device *pdev)
    > +{
    > + struct st_rng_data *ddata;
    > + struct resource *res;
    > + struct clk *clk;
    > + void __iomem *base;
    > + int ret;
    > +
    > + ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
    > + if (!ddata)
    > + return -ENOMEM;
    > +
    > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    > + base = devm_ioremap_resource(&pdev->dev, res);
    > + if (IS_ERR(base))
    > + return PTR_ERR(base);
    > +
    > + clk = devm_clk_get(&pdev->dev, NULL);
    > + if (IS_ERR(clk))
    > + return PTR_ERR(clk);
    > +
    > + ret = clk_prepare_enable(clk);
    > + if (ret)
    > + return ret;
    > +
    > + ddata->ops.priv = (unsigned long)ddata;
    > + ddata->ops.read = st_rng_read;
    > + ddata->ops.name = pdev->name;
    > + ddata->base = base;
    > + ddata->clk = clk;
    > +
    > + dev_set_drvdata(&pdev->dev, ddata);
    > +
    > + ret = hwrng_register(&ddata->ops);
    > + if (ret) {
    > + dev_err(&pdev->dev, "Failed to register HW RNG\n");
    > + return ret;
    > + }
    > +
    > + dev_info(&pdev->dev, "Successfully registered HW RNG\n");
    > +
    > + return 0;
    > +}
    > +
    > +static int st_rng_remove(struct platform_device *pdev)
    > +{
    > + struct st_rng_data *ddata = dev_get_drvdata(&pdev->dev);
    > +
    > + hwrng_unregister(&ddata->ops);
    > +
    > + clk_disable_unprepare(ddata->clk);
    > +
    > + return 0;
    > +}
    > +
    > +static const struct of_device_id st_rng_match[] = {
    > + { .compatible = "st,rng" },
    > + {},
    > +};
    > +MODULE_DEVICE_TABLE(of, st_rng_match);
    > +
    > +static struct platform_driver st_rng_driver = {
    > + .driver = {
    > + .name = "st-hwrandom",
    > + .of_match_table = of_match_ptr(st_rng_match),
    > + },
    > + .probe = st_rng_probe,
    > + .remove = st_rng_remove
    > +};
    > +
    > +module_platform_driver(st_rng_driver);
    > +
    > +MODULE_AUTHOR("Pankaj Dev <pankaj.dev@st.com>");
    > +MODULE_LICENSE("GPL v2");
    > --
    > 1.9.1
    >


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