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    Subject[PATCH 2/2] rng: pic32-rng: Add PIC32 RNG hardware driver
    Date
    Add support for the hardware pseudo and true random number generator
    peripheral found on PIC32.

    Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
    Signed-off-by: Purna Chandra Mandal <purna.mandal@microchip.com>
    ---
    drivers/char/hw_random/Kconfig | 13 +++
    drivers/char/hw_random/Makefile | 1 +
    drivers/char/hw_random/pic32-rng.c | 152 ++++++++++++++++++++++++++++++++++++
    3 files changed, 166 insertions(+)
    create mode 100644 drivers/char/hw_random/pic32-rng.c

    diff --git a/drivers/char/hw_random/Kconfig b/drivers/char/hw_random/Kconfig
    index dbf2271..3ab0c46 100644
    --- a/drivers/char/hw_random/Kconfig
    +++ b/drivers/char/hw_random/Kconfig
    @@ -381,6 +381,19 @@ config HW_RANDOM_STM32

    If unsure, say N.

    +config HW_RANDOM_PIC32
    + tristate "Microchip PIC32 Random Number Generator support"
    + depends on HW_RANDOM && MACH_PIC32
    + default y
    + ---help---
    + This driver provides kernel-side support for the Random Number
    + Generator hardware found on a PIC32.
    +
    + To compile this driver as a module, choose M here. the
    + module will be called pic32-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 5ad3976..f5a6fa7 100644
    --- a/drivers/char/hw_random/Makefile
    +++ b/drivers/char/hw_random/Makefile
    @@ -33,3 +33,4 @@ obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
    obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
    obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o
    obj-$(CONFIG_HW_RANDOM_STM32) += stm32-rng.o
    +obj-$(CONFIG_HW_RANDOM_PIC32) += pic32-rng.o
    diff --git a/drivers/char/hw_random/pic32-rng.c b/drivers/char/hw_random/pic32-rng.c
    new file mode 100644
    index 0000000..d2f32c4
    --- /dev/null
    +++ b/drivers/char/hw_random/pic32-rng.c
    @@ -0,0 +1,152 @@
    +/*
    + * PIC32 RNG driver
    + *
    + * Joshua Henderson <joshua.henderson@microchip.com>
    + * Copyright (C) 2016 Microchip Technology Inc. All rights reserved.
    + *
    + * This program is free software; you can distribute it and/or modify it
    + * under the terms of the GNU General Public License (Version 2) as
    + * published by the Free Software Foundation.
    + *
    + * This program is distributed in the hope it will be useful, but WITHOUT
    + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
    + * for more details.
    + */
    +
    +#include <linux/kernel.h>
    +#include <linux/module.h>
    +#include <linux/delay.h>
    +#include <linux/slab.h>
    +#include <linux/err.h>
    +#include <linux/io.h>
    +#include <linux/hw_random.h>
    +#include <linux/platform_device.h>
    +#include <linux/of.h>
    +#include <linux/of_device.h>
    +#include <linux/clk.h>
    +#include <linux/clkdev.h>
    +
    +#define RNGCON 0x04
    +#define TRNGEN BIT(8)
    +#define PRNGEN BIT(9)
    +#define PRNGCONT BIT(10)
    +#define TRNGMOD BIT(11)
    +#define SEEDLOAD BIT(12)
    +#define RNGPOLY1 0x08
    +#define RNGPOLY2 0x0C
    +#define RNGNUMGEN1 0x10
    +#define RNGNUMGEN2 0x14
    +#define RNGSEED1 0x18
    +#define RNGSEED2 0x1C
    +#define RNGRCNT 0x20
    +#define RCNT_MASK 0x7F
    +
    +struct pic32_rng {
    + void __iomem *base;
    + struct hwrng rng;
    + struct clk *clk;
    +};
    +
    +static int pic32_rng_read(struct hwrng *rng, void *buf, size_t max,
    + bool wait)
    +{
    + struct pic32_rng *prng = container_of(rng, struct pic32_rng, rng);
    + u64 *data = buf;
    +
    + *data = ((u64)readl(prng->base + RNGNUMGEN2) << 32) +
    + readl(prng->base + RNGNUMGEN1);
    + return 4;
    +}
    +
    +static int pic32_rng_probe(struct platform_device *pdev)
    +{
    + struct pic32_rng *prng;
    + struct resource *res;
    + u32 v, t;
    + int ret;
    +
    + prng = devm_kzalloc(&pdev->dev, sizeof(*prng), GFP_KERNEL);
    + if (!prng)
    + return -ENOMEM;
    +
    + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    + prng->base = devm_ioremap_resource(&pdev->dev, res);
    + if (IS_ERR(prng->base))
    + return PTR_ERR(prng->base);
    +
    + prng->clk = devm_clk_get(&pdev->dev, NULL);
    + if (IS_ERR(prng->clk))
    + return PTR_ERR(prng->clk);
    +
    + clk_prepare_enable(prng->clk);
    +
    + /* enable TRNG in enhanced mode */
    + v = readl(prng->base + RNGCON);
    + v &= ~(TRNGEN | PRNGEN | 0xff);
    + v |= TRNGMOD;
    + writel(v | TRNGEN, prng->base + RNGCON);
    +
    + /* wait for valid seed */
    + usleep_range(100, 200);
    + t = readl(prng->base + RNGRCNT) & RCNT_MASK;
    + if (t < 0x2A)
    + dev_warn(&pdev->dev, "seed not generated.\n");
    +
    + /* load initial seed */
    + writel(v | SEEDLOAD, prng->base + RNGCON);
    +
    + /* load initial polynomial: 42bit poly */
    + writel(0x00c00003, prng->base + RNGPOLY1);
    + writel(0x00000000, prng->base + RNGPOLY2);
    +
    + /* start PRNG to generate 42bit random */
    + v |= 0x2A | PRNGCONT | PRNGEN;
    + writel(v, prng->base + RNGCON);
    +
    + prng->rng.name = pdev->name;
    + prng->rng.read = pic32_rng_read;
    +
    + ret = hwrng_register(&prng->rng);
    + if (ret)
    + goto err_register;
    +
    + platform_set_drvdata(pdev, prng);
    +
    + return 0;
    +
    +err_register:
    + return ret;
    +}
    +
    +static int pic32_rng_remove(struct platform_device *pdev)
    +{
    + struct pic32_rng *rng = platform_get_drvdata(pdev);
    +
    + hwrng_unregister(&rng->rng);
    + writel(0, rng->base + RNGCON);
    + clk_disable_unprepare(rng->clk);
    + return 0;
    +}
    +
    +static const struct of_device_id pic32_rng_of_match[] = {
    + { .compatible = "microchip,pic32mzda-rng", },
    + { /* sentinel */ }
    +};
    +MODULE_DEVICE_TABLE(of, pic32_rng_of_match);
    +
    +static struct platform_driver pic32_rng_driver = {
    + .probe = pic32_rng_probe,
    + .remove = pic32_rng_remove,
    + .driver = {
    + .name = "pic32-rng",
    + .owner = THIS_MODULE,
    + .of_match_table = of_match_ptr(pic32_rng_of_match),
    + },
    +};
    +
    +module_platform_driver(pic32_rng_driver);
    +
    +MODULE_LICENSE("GPL");
    +MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>");
    +MODULE_DESCRIPTION("Microchip PIC32 RNG Driver");
    --
    1.7.9.5
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