LXR linux/drivers/char/hw_random/pasemi-rng.c

   1/*
   2 * Copyright (C) 2006-2007 PA Semi, Inc
   3 *
   4 * Maintained by: Olof Johansson <olof@lixom.net>
   5 *
   6 * Driver for the PWRficient onchip rng
   7 *
   8 * This program is free software; you can redistribute it and/or modify
   9 * it under the terms of the GNU General Public License version 2 as
  10 * published by the Free Software Foundation.
  11 *
  12 * This program is distributed in the hope that it will be useful,
  13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 * GNU General Public License for more details.
  16 *
  17 * You should have received a copy of the GNU General Public License
  18 * along with this program; if not, write to the Free Software
  19 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  20 */
  21
  22#include <linux/module.h>
  23#include <linux/kernel.h>
  24#include <linux/platform_device.h>
  25#include <linux/hw_random.h>
  26#include <linux/delay.h>
  27#include <linux/of_address.h>
  28#include <linux/of_platform.h>
  29#include <linux/io.h>
  30
  31#define SDCRNG_CTL_REG                  0x00
  32#define   SDCRNG_CTL_FVLD_M             0x0000f000
  33#define   SDCRNG_CTL_FVLD_S             12
  34#define   SDCRNG_CTL_KSZ                0x00000800
  35#define   SDCRNG_CTL_RSRC_CRG           0x00000010
  36#define   SDCRNG_CTL_RSRC_RRG           0x00000000
  37#define   SDCRNG_CTL_CE                 0x00000004
  38#define   SDCRNG_CTL_RE                 0x00000002
  39#define   SDCRNG_CTL_DR                 0x00000001
  40#define   SDCRNG_CTL_SELECT_RRG_RNG     (SDCRNG_CTL_RE | SDCRNG_CTL_RSRC_RRG)
  41#define   SDCRNG_CTL_SELECT_CRG_RNG     (SDCRNG_CTL_CE | SDCRNG_CTL_RSRC_CRG)
  42#define SDCRNG_VAL_REG                  0x20
  43
  44#define MODULE_NAME "pasemi_rng"
  45
  46static int pasemi_rng_data_present(struct hwrng *rng, int wait)
  47{
  48        void __iomem *rng_regs = (void __iomem *)rng->priv;
  49        int data, i;
  50
  51        for (i = 0; i < 20; i++) {
  52                data = (in_le32(rng_regs + SDCRNG_CTL_REG)
  53                        & SDCRNG_CTL_FVLD_M) ? 1 : 0;
  54                if (data || !wait)
  55                        break;
  56                udelay(10);
  57        }
  58        return data;
  59}
  60
  61static int pasemi_rng_data_read(struct hwrng *rng, u32 *data)
  62{
  63        void __iomem *rng_regs = (void __iomem *)rng->priv;
  64        *data = in_le32(rng_regs + SDCRNG_VAL_REG);
  65        return 4;
  66}
  67
  68static int pasemi_rng_init(struct hwrng *rng)
  69{
  70        void __iomem *rng_regs = (void __iomem *)rng->priv;
  71        u32 ctl;
  72
  73        ctl = SDCRNG_CTL_DR | SDCRNG_CTL_SELECT_RRG_RNG | SDCRNG_CTL_KSZ;
  74        out_le32(rng_regs + SDCRNG_CTL_REG, ctl);
  75        out_le32(rng_regs + SDCRNG_CTL_REG, ctl & ~SDCRNG_CTL_DR);
  76
  77        return 0;
  78}
  79
  80static void pasemi_rng_cleanup(struct hwrng *rng)
  81{
  82        void __iomem *rng_regs = (void __iomem *)rng->priv;
  83        u32 ctl;
  84
  85        ctl = SDCRNG_CTL_RE | SDCRNG_CTL_CE;
  86        out_le32(rng_regs + SDCRNG_CTL_REG,
  87                 in_le32(rng_regs + SDCRNG_CTL_REG) & ~ctl);
  88}
  89
  90static struct hwrng pasemi_rng = {
  91        .name           = MODULE_NAME,
  92        .init           = pasemi_rng_init,
  93        .cleanup        = pasemi_rng_cleanup,
  94        .data_present   = pasemi_rng_data_present,
  95        .data_read      = pasemi_rng_data_read,
  96};
  97
  98static int rng_probe(struct platform_device *pdev)
  99{
 100        void __iomem *rng_regs;
 101        struct resource *res;
 102
 103        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 104        rng_regs = devm_ioremap_resource(&pdev->dev, res);
 105        if (IS_ERR(rng_regs))
 106                return PTR_ERR(rng_regs);
 107
 108        pasemi_rng.priv = (unsigned long)rng_regs;
 109
 110        pr_info("Registering PA Semi RNG\n");
 111        return devm_hwrng_register(&pdev->dev, &pasemi_rng);
 112}
 113
 114static const struct of_device_id rng_match[] = {
 115        { .compatible      = "1682m-rng", },
 116        { .compatible      = "pasemi,pwrficient-rng", },
 117        { },
 118};
 119MODULE_DEVICE_TABLE(of, rng_match);
 120
 121static struct platform_driver rng_driver = {
 122        .driver = {
 123                .name = "pasemi-rng",
 124                .of_match_table = rng_match,
 125        },
 126        .probe          = rng_probe,
 127};
 128
 129module_platform_driver(rng_driver);
 130
 131MODULE_LICENSE("GPL");
 132MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>");
 133MODULE_DESCRIPTION("H/W RNG driver for PA Semi processor");
 134