drivers/crypto/qcom-rng.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 // Copyright (c) 2017-18 Linaro Limited
   3 //
   4 // Based on msm-rng.c and downstream driver
   5
   6 #include <crypto/internal/rng.h>
   7 #include <linux/acpi.h>
   8 #include <linux/clk.h>
   9 #include <linux/crypto.h>
  10 #include <linux/hw_random.h>
  11 #include <linux/io.h>
  12 #include <linux/iopoll.h>
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/of.h>
  16 #include <linux/platform_device.h>
  17
  18 /* Device specific register offsets */
  19 #define PRNG_DATA_OUT           0x0000
  20 #define PRNG_STATUS             0x0004
  21 #define PRNG_LFSR_CFG           0x0100
  22 #define PRNG_CONFIG             0x0104
  23
  24 /* Device specific register masks and config values */
  25 #define PRNG_LFSR_CFG_MASK      0x0000ffff
  26 #define PRNG_LFSR_CFG_CLOCKS    0x0000dddd
  27 #define PRNG_CONFIG_HW_ENABLE   BIT(1)
  28 #define PRNG_STATUS_DATA_AVAIL  BIT(0)
  29
  30 #define WORD_SZ                 4
  31
  32 #define QCOM_TRNG_QUALITY       1024
  33
  34 struct qcom_rng {
  35         struct mutex lock;
  36         void __iomem *base;
  37         struct clk *clk;
  38         struct hwrng hwrng;
  39         struct qcom_rng_match_data *match_data;
  40 };
  41
  42 struct qcom_rng_ctx {
  43         struct qcom_rng *rng;
  44 };
  45
  46 struct qcom_rng_match_data {
  47         bool skip_init;
  48         bool hwrng_support;
  49 };
  50
  51 static struct qcom_rng *qcom_rng_dev;
  52
  53 static int qcom_rng_read(struct qcom_rng *rng, u8 *data, unsigned int max)
  54 {
  55         unsigned int currsize = 0;
  56         u32 val;
  57         int ret;
  58
  59         /* read random data from hardware */
  60         do {
  61                 ret = readl_poll_timeout(rng->base + PRNG_STATUS, val,
  62                                          val & PRNG_STATUS_DATA_AVAIL,
  63                                          200, 10000);
  64                 if (ret)
  65                         return ret;
  66
  67                 val = readl_relaxed(rng->base + PRNG_DATA_OUT);
  68                 if (!val)
  69                         return -EINVAL;
  70
  71                 if ((max - currsize) >= WORD_SZ) {
  72                         memcpy(data, &val, WORD_SZ);
  73                         data += WORD_SZ;
  74                         currsize += WORD_SZ;
  75                 } else {
  76                         /* copy only remaining bytes */
  77                         memcpy(data, &val, max - currsize);
  78                         currsize = max;
  79                 }
  80         } while (currsize < max);
  81
  82         return currsize;
  83 }
  84
  85 static int qcom_rng_generate(struct crypto_rng *tfm,
  86                              const u8 *src, unsigned int slen,
  87                              u8 *dstn, unsigned int dlen)
  88 {
  89         struct qcom_rng_ctx *ctx = crypto_rng_ctx(tfm);
  90         struct qcom_rng *rng = ctx->rng;
  91         int ret;
  92
  93         ret = clk_prepare_enable(rng->clk);
  94         if (ret)
  95                 return ret;
  96
  97         mutex_lock(&rng->lock);
  98
  99         ret = qcom_rng_read(rng, dstn, dlen);
 100
 101         mutex_unlock(&rng->lock);
 102         clk_disable_unprepare(rng->clk);
 103
 104         if (ret >= 0)
 105                 ret = 0;
 106
 107         return ret;
 108 }
 109
 110 static int qcom_rng_seed(struct crypto_rng *tfm, const u8 *seed,
 111                          unsigned int slen)
 112 {
 113         return 0;
 114 }
 115
 116 static int qcom_hwrng_read(struct hwrng *hwrng, void *data, size_t max, bool wait)
 117 {
 118         struct qcom_rng *qrng = container_of(hwrng, struct qcom_rng, hwrng);
 119
 120         return qcom_rng_read(qrng, data, max);
 121 }
 122
 123 static int qcom_rng_enable(struct qcom_rng *rng)
 124 {
 125         u32 val;
 126         int ret;
 127
 128         ret = clk_prepare_enable(rng->clk);
 129         if (ret)
 130                 return ret;
 131
 132         /* Enable PRNG only if it is not already enabled */
 133         val = readl_relaxed(rng->base + PRNG_CONFIG);
 134         if (val & PRNG_CONFIG_HW_ENABLE)
 135                 goto already_enabled;
 136
 137         val = readl_relaxed(rng->base + PRNG_LFSR_CFG);
 138         val &= ~PRNG_LFSR_CFG_MASK;
 139         val |= PRNG_LFSR_CFG_CLOCKS;
 140         writel(val, rng->base + PRNG_LFSR_CFG);
 141
 142         val = readl_relaxed(rng->base + PRNG_CONFIG);
 143         val |= PRNG_CONFIG_HW_ENABLE;
 144         writel(val, rng->base + PRNG_CONFIG);
 145
 146 already_enabled:
 147         clk_disable_unprepare(rng->clk);
 148
 149         return 0;
 150 }
 151
 152 static int qcom_rng_init(struct crypto_tfm *tfm)
 153 {
 154         struct qcom_rng_ctx *ctx = crypto_tfm_ctx(tfm);
 155
 156         ctx->rng = qcom_rng_dev;
 157
 158         if (!ctx->rng->match_data->skip_init)
 159                 return qcom_rng_enable(ctx->rng);
 160
 161         return 0;
 162 }
 163
 164 static struct rng_alg qcom_rng_alg = {
 165         .generate       = qcom_rng_generate,
 166         .seed           = qcom_rng_seed,
 167         .seedsize       = 0,
 168         .base           = {
 169                 .cra_name               = "stdrng",
 170                 .cra_driver_name        = "qcom-rng",
 171                 .cra_flags              = CRYPTO_ALG_TYPE_RNG,
 172                 .cra_priority           = 300,
 173                 .cra_ctxsize            = sizeof(struct qcom_rng_ctx),
 174                 .cra_module             = THIS_MODULE,
 175                 .cra_init               = qcom_rng_init,
 176         }
 177 };
 178
 179 static int qcom_rng_probe(struct platform_device *pdev)
 180 {
 181         struct qcom_rng *rng;
 182         int ret;
 183
 184         rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
 185         if (!rng)
 186                 return -ENOMEM;
 187
 188         platform_set_drvdata(pdev, rng);
 189         mutex_init(&rng->lock);
 190
 191         rng->base = devm_platform_ioremap_resource(pdev, 0);
 192         if (IS_ERR(rng->base))
 193                 return PTR_ERR(rng->base);
 194
 195         rng->clk = devm_clk_get_optional(&pdev->dev, "core");
 196         if (IS_ERR(rng->clk))
 197                 return PTR_ERR(rng->clk);
 198
 199         rng->match_data = (struct qcom_rng_match_data *)device_get_match_data(&pdev->dev);
 200
 201         qcom_rng_dev = rng;
 202         ret = crypto_register_rng(&qcom_rng_alg);
 203         if (ret) {
 204                 dev_err(&pdev->dev, "Register crypto rng failed: %d\n", ret);
 205                 qcom_rng_dev = NULL;
 206                 return ret;
 207         }
 208
 209         if (rng->match_data->hwrng_support) {
 210                 rng->hwrng.name = "qcom_hwrng";
 211                 rng->hwrng.read = qcom_hwrng_read;
 212                 rng->hwrng.quality = QCOM_TRNG_QUALITY;
 213                 ret = devm_hwrng_register(&pdev->dev, &rng->hwrng);
 214                 if (ret) {
 215                         dev_err(&pdev->dev, "Register hwrng failed: %d\n", ret);
 216                         qcom_rng_dev = NULL;
 217                         goto fail;
 218                 }
 219         }
 220
 221         return ret;
 222 fail:
 223         crypto_unregister_rng(&qcom_rng_alg);
 224         return ret;
 225 }
 226
 227 static void qcom_rng_remove(struct platform_device *pdev)
 228 {
 229         crypto_unregister_rng(&qcom_rng_alg);
 230
 231         qcom_rng_dev = NULL;
 232 }
 233
 234 static struct qcom_rng_match_data qcom_prng_match_data = {
 235         .skip_init = false,
 236         .hwrng_support = false,
 237 };
 238
 239 static struct qcom_rng_match_data qcom_prng_ee_match_data = {
 240         .skip_init = true,
 241         .hwrng_support = false,
 242 };
 243
 244 static struct qcom_rng_match_data qcom_trng_match_data = {
 245         .skip_init = true,
 246         .hwrng_support = true,
 247 };
 248
 249 static const struct acpi_device_id __maybe_unused qcom_rng_acpi_match[] = {
 250         { .id = "QCOM8160", .driver_data = (kernel_ulong_t)&qcom_prng_ee_match_data },
 251         {}
 252 };
 253 MODULE_DEVICE_TABLE(acpi, qcom_rng_acpi_match);
 254
 255 static const struct of_device_id __maybe_unused qcom_rng_of_match[] = {
 256         { .compatible = "qcom,prng", .data = &qcom_prng_match_data },
 257         { .compatible = "qcom,prng-ee", .data = &qcom_prng_ee_match_data },
 258         { .compatible = "qcom,trng", .data = &qcom_trng_match_data },
 259         {}
 260 };
 261 MODULE_DEVICE_TABLE(of, qcom_rng_of_match);
 262
 263 static struct platform_driver qcom_rng_driver = {
 264         .probe = qcom_rng_probe,
 265         .remove =  qcom_rng_remove,
 266         .driver = {
 267                 .name = KBUILD_MODNAME,
 268                 .of_match_table = of_match_ptr(qcom_rng_of_match),
 269                 .acpi_match_table = ACPI_PTR(qcom_rng_acpi_match),
 270         }
 271 };
 272 module_platform_driver(qcom_rng_driver);
 273
 274 MODULE_ALIAS("platform:" KBUILD_MODNAME);
 275 MODULE_DESCRIPTION("Qualcomm random number generator driver");
 276 MODULE_LICENSE("GPL v2");