drivers/crypto/amcc/crypto4xx_trng.c

   1 /*
   2  * Generic PowerPC 44x RNG driver
   3  *
   4  * Copyright 2011 IBM Corporation
   5  *
   6  * This program is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by the
   8  * Free Software Foundation; version 2 of the License.
   9  */
  10
  11 #include <linux/module.h>
  12 #include <linux/kernel.h>
  13 #include <linux/interrupt.h>
  14 #include <linux/platform_device.h>
  15 #include <linux/hw_random.h>
  16 #include <linux/delay.h>
  17 #include <linux/of_address.h>
  18 #include <linux/of_platform.h>
  19 #include <linux/io.h>
  20
  21 #include "crypto4xx_core.h"
  22 #include "crypto4xx_trng.h"
  23 #include "crypto4xx_reg_def.h"
  24
  25 #define PPC4XX_TRNG_CTRL        0x0008
  26 #define PPC4XX_TRNG_CTRL_DALM   0x20
  27 #define PPC4XX_TRNG_STAT        0x0004
  28 #define PPC4XX_TRNG_STAT_B      0x1
  29 #define PPC4XX_TRNG_DATA        0x0000
  30
  31 static int ppc4xx_trng_data_present(struct hwrng *rng, int wait)
  32 {
  33         struct crypto4xx_device *dev = (void *)rng->priv;
  34         int busy, i, present = 0;
  35
  36         for (i = 0; i < 20; i++) {
  37                 busy = (in_le32(dev->trng_base + PPC4XX_TRNG_STAT) &
  38                         PPC4XX_TRNG_STAT_B);
  39                 if (!busy || !wait) {
  40                         present = 1;
  41                         break;
  42                 }
  43                 udelay(10);
  44         }
  45         return present;
  46 }
  47
  48 static int ppc4xx_trng_data_read(struct hwrng *rng, u32 *data)
  49 {
  50         struct crypto4xx_device *dev = (void *)rng->priv;
  51         *data = in_le32(dev->trng_base + PPC4XX_TRNG_DATA);
  52         return 4;
  53 }
  54
  55 static void ppc4xx_trng_enable(struct crypto4xx_device *dev, bool enable)
  56 {
  57         u32 device_ctrl;
  58
  59         device_ctrl = readl(dev->ce_base + CRYPTO4XX_DEVICE_CTRL);
  60         if (enable)
  61                 device_ctrl |= PPC4XX_TRNG_EN;
  62         else
  63                 device_ctrl &= ~PPC4XX_TRNG_EN;
  64         writel(device_ctrl, dev->ce_base + CRYPTO4XX_DEVICE_CTRL);
  65 }
  66
  67 static const struct of_device_id ppc4xx_trng_match[] = {
  68         { .compatible = "ppc4xx-rng", },
  69         { .compatible = "amcc,ppc460ex-rng", },
  70         { .compatible = "amcc,ppc440epx-rng", },
  71         {},
  72 };
  73
  74 void ppc4xx_trng_probe(struct crypto4xx_core_device *core_dev)
  75 {
  76         struct crypto4xx_device *dev = core_dev->dev;
  77         struct device_node *trng = NULL;
  78         struct hwrng *rng = NULL;
  79         int err;
  80
  81         /* Find the TRNG device node and map it */
  82         trng = of_find_matching_node(NULL, ppc4xx_trng_match);
  83         if (!trng || !of_device_is_available(trng)) {
  84                 of_node_put(trng);
  85                 return;
  86         }
  87
  88         dev->trng_base = of_iomap(trng, 0);
  89         of_node_put(trng);
  90         if (!dev->trng_base)
  91                 goto err_out;
  92
  93         rng = kzalloc(sizeof(*rng), GFP_KERNEL);
  94         if (!rng)
  95                 goto err_out;
  96
  97         rng->name = KBUILD_MODNAME;
  98         rng->data_present = ppc4xx_trng_data_present;
  99         rng->data_read = ppc4xx_trng_data_read;
 100         rng->priv = (unsigned long) dev;
 101         core_dev->trng = rng;
 102         ppc4xx_trng_enable(dev, true);
 103         out_le32(dev->trng_base + PPC4XX_TRNG_CTRL, PPC4XX_TRNG_CTRL_DALM);
 104         err = devm_hwrng_register(core_dev->device, core_dev->trng);
 105         if (err) {
 106                 ppc4xx_trng_enable(dev, false);
 107                 dev_err(core_dev->device, "failed to register hwrng (%d).\n",
 108                         err);
 109                 goto err_out;
 110         }
 111         return;
 112
 113 err_out:
 114         of_node_put(trng);
 115         iounmap(dev->trng_base);
 116         kfree(rng);
 117         dev->trng_base = NULL;
 118         core_dev->trng = NULL;
 119 }
 120
 121 void ppc4xx_trng_remove(struct crypto4xx_core_device *core_dev)
 122 {
 123         if (core_dev && core_dev->trng) {
 124                 struct crypto4xx_device *dev = core_dev->dev;
 125
 126                 devm_hwrng_unregister(core_dev->device, core_dev->trng);
 127                 ppc4xx_trng_enable(dev, false);
 128                 iounmap(dev->trng_base);
 129                 kfree(core_dev->trng);
 130         }
 131 }
 132
 133 MODULE_ALIAS("ppc4xx_rng");