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    Subject[PATCH v2 5/7] hwrng: st: Add support for ST's HW Random Number Generator
    Date
    Signed-off-by: Pankaj Dev <pankaj.dev@st.com>
    Signed-off-by: Lee Jones <lee.jones@linaro.org>
    ---
    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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