drivers/char/hw_random/cn10k-rng.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Marvell CN10K RVU Hardware Random Number Generator.
   3  *
   4  * Copyright (C) 2021 Marvell.
   5  *
   6  */
   7
   8 #include <linux/hw_random.h>
   9 #include <linux/io.h>
  10 #include <linux/module.h>
  11 #include <linux/pci.h>
  12 #include <linux/pci_ids.h>
  13 #include <linux/delay.h>
  14
  15 #include <linux/arm-smccc.h>
  16
  17 /* CSRs */
  18 #define RNM_CTL_STATUS          0x000
  19 #define RNM_ENTROPY_STATUS      0x008
  20 #define RNM_CONST               0x030
  21 #define RNM_EBG_ENT             0x048
  22 #define RNM_PF_EBG_HEALTH       0x050
  23 #define RNM_PF_RANDOM           0x400
  24 #define RNM_TRNG_RESULT         0x408
  25
  26 /* Extended TRNG Read and Status Registers */
  27 #define RNM_PF_TRNG_DAT         0x1000
  28 #define RNM_PF_TRNG_RES         0x1008
  29
  30 struct cn10k_rng {
  31         void __iomem *reg_base;
  32         struct hwrng ops;
  33         struct pci_dev *pdev;
  34         /* Octeon CN10K-A A0/A1, CNF10K-A A0/A1 and CNF10K-B A0/B0
  35          * does not support extended TRNG registers
  36          */
  37         bool extended_trng_regs;
  38 };
  39
  40 #define PLAT_OCTEONTX_RESET_RNG_EBG_HEALTH_STATE     0xc2000b0f
  41
  42 #define PCI_SUBSYS_DEVID_CN10K_A_RNG    0xB900
  43 #define PCI_SUBSYS_DEVID_CNF10K_A_RNG   0xBA00
  44 #define PCI_SUBSYS_DEVID_CNF10K_B_RNG   0xBC00
  45
  46 static bool cn10k_is_extended_trng_regs_supported(struct pci_dev *pdev)
  47 {
  48         /* CN10K-A A0/A1 */
  49         if ((pdev->subsystem_device == PCI_SUBSYS_DEVID_CN10K_A_RNG) &&
  50             (!pdev->revision || (pdev->revision & 0xff) == 0x50 ||
  51              (pdev->revision & 0xff) == 0x51))
  52                 return false;
  53
  54         /* CNF10K-A A0 */
  55         if ((pdev->subsystem_device == PCI_SUBSYS_DEVID_CNF10K_A_RNG) &&
  56             (!pdev->revision || (pdev->revision & 0xff) == 0x60 ||
  57              (pdev->revision & 0xff) == 0x61))
  58                 return false;
  59
  60         /* CNF10K-B A0/B0 */
  61         if ((pdev->subsystem_device == PCI_SUBSYS_DEVID_CNF10K_B_RNG) &&
  62             (!pdev->revision || (pdev->revision & 0xff) == 0x70 ||
  63              (pdev->revision & 0xff) == 0x74))
  64                 return false;
  65
  66         return true;
  67 }
  68
  69 static unsigned long reset_rng_health_state(struct cn10k_rng *rng)
  70 {
  71         struct arm_smccc_res res;
  72
  73         /* Send SMC service call to reset EBG health state */
  74         arm_smccc_smc(PLAT_OCTEONTX_RESET_RNG_EBG_HEALTH_STATE, 0, 0, 0, 0, 0, 0, 0, &res);
  75         return res.a0;
  76 }
  77
  78 static int check_rng_health(struct cn10k_rng *rng)
  79 {
  80         u64 status;
  81         unsigned long err;
  82
  83         /* Skip checking health */
  84         if (!rng->reg_base)
  85                 return -ENODEV;
  86
  87         status = readq(rng->reg_base + RNM_PF_EBG_HEALTH);
  88         if (status & BIT_ULL(20)) {
  89                 err = reset_rng_health_state(rng);
  90                 if (err) {
  91                         dev_err(&rng->pdev->dev, "HWRNG: Health test failed (status=%llx)\n",
  92                                         status);
  93                         dev_err(&rng->pdev->dev, "HWRNG: error during reset (error=%lx)\n",
  94                                         err);
  95                         return -EIO;
  96                 }
  97         }
  98         return 0;
  99 }
 100
 101 /* Returns true when valid data available otherwise return false */
 102 static bool cn10k_read_trng(struct cn10k_rng *rng, u64 *value)
 103 {
 104         u16 retry_count = 0;
 105         u64 upper, lower;
 106         u64 status;
 107
 108         if (rng->extended_trng_regs) {
 109                 do {
 110                         *value = readq(rng->reg_base + RNM_PF_TRNG_DAT);
 111                         if (*value)
 112                                 return true;
 113                         status = readq(rng->reg_base + RNM_PF_TRNG_RES);
 114                         if (!status && (retry_count++ > 0x1000))
 115                                 return false;
 116                 } while (!status);
 117         }
 118
 119         *value = readq(rng->reg_base + RNM_PF_RANDOM);
 120
 121         /* HW can run out of entropy if large amount random data is read in
 122          * quick succession. Zeros may not be real random data from HW.
 123          */
 124         if (!*value) {
 125                 upper = readq(rng->reg_base + RNM_PF_RANDOM);
 126                 lower = readq(rng->reg_base + RNM_PF_RANDOM);
 127                 while (!(upper & 0x00000000FFFFFFFFULL))
 128                         upper = readq(rng->reg_base + RNM_PF_RANDOM);
 129                 while (!(lower & 0xFFFFFFFF00000000ULL))
 130                         lower = readq(rng->reg_base + RNM_PF_RANDOM);
 131
 132                 *value = (upper & 0xFFFFFFFF00000000) | (lower & 0xFFFFFFFF);
 133         }
 134         return true;
 135 }
 136
 137 static int cn10k_rng_read(struct hwrng *hwrng, void *data,
 138                           size_t max, bool wait)
 139 {
 140         struct cn10k_rng *rng = (struct cn10k_rng *)hwrng->priv;
 141         unsigned int size;
 142         u8 *pos = data;
 143         int err = 0;
 144         u64 value;
 145
 146         err = check_rng_health(rng);
 147         if (err)
 148                 return err;
 149
 150         size = max;
 151
 152         while (size >= 8) {
 153                 if (!cn10k_read_trng(rng, &value))
 154                         goto out;
 155
 156                 *((u64 *)pos) = value;
 157                 size -= 8;
 158                 pos += 8;
 159         }
 160
 161         if (size > 0) {
 162                 if (!cn10k_read_trng(rng, &value))
 163                         goto out;
 164
 165                 while (size > 0) {
 166                         *pos = (u8)value;
 167                         value >>= 8;
 168                         size--;
 169                         pos++;
 170                 }
 171         }
 172
 173 out:
 174         return max - size;
 175 }
 176
 177 static int cn10k_rng_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 178 {
 179         struct  cn10k_rng *rng;
 180         int     err;
 181
 182         rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
 183         if (!rng)
 184                 return -ENOMEM;
 185
 186         rng->pdev = pdev;
 187         pci_set_drvdata(pdev, rng);
 188
 189         rng->reg_base = pcim_iomap(pdev, 0, 0);
 190         if (!rng->reg_base) {
 191                 dev_err(&pdev->dev, "Error while mapping CSRs, exiting\n");
 192                 return -ENOMEM;
 193         }
 194
 195         rng->ops.name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
 196                                        "cn10k-rng-%s", dev_name(&pdev->dev));
 197         if (!rng->ops.name)
 198                 return -ENOMEM;
 199
 200         rng->ops.read = cn10k_rng_read;
 201         rng->ops.priv = (unsigned long)rng;
 202
 203         rng->extended_trng_regs = cn10k_is_extended_trng_regs_supported(pdev);
 204
 205         reset_rng_health_state(rng);
 206
 207         err = devm_hwrng_register(&pdev->dev, &rng->ops);
 208         if (err) {
 209                 dev_err(&pdev->dev, "Could not register hwrng device.\n");
 210                 return err;
 211         }
 212
 213         return 0;
 214 }
 215
 216 static void cn10k_rng_remove(struct pci_dev *pdev)
 217 {
 218         /* Nothing to do */
 219 }
 220
 221 static const struct pci_device_id cn10k_rng_id_table[] = {
 222         { PCI_DEVICE(PCI_VENDOR_ID_CAVIUM, 0xA098) }, /* RNG PF */
 223         {0,},
 224 };
 225
 226 MODULE_DEVICE_TABLE(pci, cn10k_rng_id_table);
 227
 228 static struct pci_driver cn10k_rng_driver = {
 229         .name           = "cn10k_rng",
 230         .id_table       = cn10k_rng_id_table,
 231         .probe          = cn10k_rng_probe,
 232         .remove         = cn10k_rng_remove,
 233 };
 234
 235 module_pci_driver(cn10k_rng_driver);
 236 MODULE_AUTHOR("Sunil Goutham <sgoutham@marvell.com>");
 237 MODULE_DESCRIPTION("Marvell CN10K HW RNG Driver");
 238 MODULE_LICENSE("GPL v2");