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/module.h>
  11 #include <linux/of.h>
  12 #include <linux/platform_device.h>
  13
  14 /* Device specific register offsets */
  15 #define PRNG_DATA_OUT           0x0000
  16 #define PRNG_STATUS             0x0004
  17 #define PRNG_LFSR_CFG           0x0100
  18 #define PRNG_CONFIG             0x0104
  19
  20 /* Device specific register masks and config values */
  21 #define PRNG_LFSR_CFG_MASK      0x0000ffff
  22 #define PRNG_LFSR_CFG_CLOCKS    0x0000dddd
  23 #define PRNG_CONFIG_HW_ENABLE   BIT(1)
  24 #define PRNG_STATUS_DATA_AVAIL  BIT(0)
  25
  26 #define WORD_SZ                 4
  27
  28 struct qcom_rng {
  29         struct mutex lock;
  30         void __iomem *base;
  31         struct clk *clk;
  32         unsigned int skip_init;
  33 };
  34
  35 struct qcom_rng_ctx {
  36         struct qcom_rng *rng;
  37 };
  38
  39 static struct qcom_rng *qcom_rng_dev;
  40
  41 static int qcom_rng_read(struct qcom_rng *rng, u8 *data, unsigned int max)
  42 {
  43         unsigned int currsize = 0;
  44         u32 val;
  45
  46         /* read random data from hardware */
  47         do {
  48                 val = readl_relaxed(rng->base + PRNG_STATUS);
  49                 if (!(val & PRNG_STATUS_DATA_AVAIL))
  50                         break;
  51
  52                 val = readl_relaxed(rng->base + PRNG_DATA_OUT);
  53                 if (!val)
  54                         break;
  55
  56                 if ((max - currsize) >= WORD_SZ) {
  57                         memcpy(data, &val, WORD_SZ);
  58                         data += WORD_SZ;
  59                         currsize += WORD_SZ;
  60                 } else {
  61                         /* copy only remaining bytes */
  62                         memcpy(data, &val, max - currsize);
  63                         break;
  64                 }
  65         } while (currsize < max);
  66
  67         return currsize;
  68 }
  69
  70 static int qcom_rng_generate(struct crypto_rng *tfm,
  71                              const u8 *src, unsigned int slen,
  72                              u8 *dstn, unsigned int dlen)
  73 {
  74         struct qcom_rng_ctx *ctx = crypto_rng_ctx(tfm);
  75         struct qcom_rng *rng = ctx->rng;
  76         int ret;
  77
  78         ret = clk_prepare_enable(rng->clk);
  79         if (ret)
  80                 return ret;
  81
  82         mutex_lock(&rng->lock);
  83
  84         ret = qcom_rng_read(rng, dstn, dlen);
  85
  86         mutex_unlock(&rng->lock);
  87         clk_disable_unprepare(rng->clk);
  88
  89         return 0;
  90 }
  91
  92 static int qcom_rng_seed(struct crypto_rng *tfm, const u8 *seed,
  93                          unsigned int slen)
  94 {
  95         return 0;
  96 }
  97
  98 static int qcom_rng_enable(struct qcom_rng *rng)
  99 {
 100         u32 val;
 101         int ret;
 102
 103         ret = clk_prepare_enable(rng->clk);
 104         if (ret)
 105                 return ret;
 106
 107         /* Enable PRNG only if it is not already enabled */
 108         val = readl_relaxed(rng->base + PRNG_CONFIG);
 109         if (val & PRNG_CONFIG_HW_ENABLE)
 110                 goto already_enabled;
 111
 112         val = readl_relaxed(rng->base + PRNG_LFSR_CFG);
 113         val &= ~PRNG_LFSR_CFG_MASK;
 114         val |= PRNG_LFSR_CFG_CLOCKS;
 115         writel(val, rng->base + PRNG_LFSR_CFG);
 116
 117         val = readl_relaxed(rng->base + PRNG_CONFIG);
 118         val |= PRNG_CONFIG_HW_ENABLE;
 119         writel(val, rng->base + PRNG_CONFIG);
 120
 121 already_enabled:
 122         clk_disable_unprepare(rng->clk);
 123
 124         return 0;
 125 }
 126
 127 static int qcom_rng_init(struct crypto_tfm *tfm)
 128 {
 129         struct qcom_rng_ctx *ctx = crypto_tfm_ctx(tfm);
 130
 131         ctx->rng = qcom_rng_dev;
 132
 133         if (!ctx->rng->skip_init)
 134                 return qcom_rng_enable(ctx->rng);
 135
 136         return 0;
 137 }
 138
 139 static struct rng_alg qcom_rng_alg = {
 140         .generate       = qcom_rng_generate,
 141         .seed           = qcom_rng_seed,
 142         .seedsize       = 0,
 143         .base           = {
 144                 .cra_name               = "stdrng",
 145                 .cra_driver_name        = "qcom-rng",
 146                 .cra_flags              = CRYPTO_ALG_TYPE_RNG,
 147                 .cra_priority           = 300,
 148                 .cra_ctxsize            = sizeof(struct qcom_rng_ctx),
 149                 .cra_module             = THIS_MODULE,
 150                 .cra_init               = qcom_rng_init,
 151         }
 152 };
 153
 154 static int qcom_rng_probe(struct platform_device *pdev)
 155 {
 156         struct qcom_rng *rng;
 157         int ret;
 158
 159         rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL);
 160         if (!rng)
 161                 return -ENOMEM;
 162
 163         platform_set_drvdata(pdev, rng);
 164         mutex_init(&rng->lock);
 165
 166         rng->base = devm_platform_ioremap_resource(pdev, 0);
 167         if (IS_ERR(rng->base))
 168                 return PTR_ERR(rng->base);
 169
 170         /* ACPI systems have clk already on, so skip clk_get */
 171         if (!has_acpi_companion(&pdev->dev)) {
 172                 rng->clk = devm_clk_get(&pdev->dev, "core");
 173                 if (IS_ERR(rng->clk))
 174                         return PTR_ERR(rng->clk);
 175         }
 176
 177
 178         rng->skip_init = (unsigned long)device_get_match_data(&pdev->dev);
 179
 180         qcom_rng_dev = rng;
 181         ret = crypto_register_rng(&qcom_rng_alg);
 182         if (ret) {
 183                 dev_err(&pdev->dev, "Register crypto rng failed: %d\n", ret);
 184                 qcom_rng_dev = NULL;
 185         }
 186
 187         return ret;
 188 }
 189
 190 static int qcom_rng_remove(struct platform_device *pdev)
 191 {
 192         crypto_unregister_rng(&qcom_rng_alg);
 193
 194         qcom_rng_dev = NULL;
 195
 196         return 0;
 197 }
 198
 199 #if IS_ENABLED(CONFIG_ACPI)
 200 static const struct acpi_device_id qcom_rng_acpi_match[] = {
 201         { .id = "QCOM8160", .driver_data = 1 },
 202         {}
 203 };
 204 MODULE_DEVICE_TABLE(acpi, qcom_rng_acpi_match);
 205 #endif
 206
 207 static const struct of_device_id qcom_rng_of_match[] = {
 208         { .compatible = "qcom,prng", .data = (void *)0},
 209         { .compatible = "qcom,prng-ee", .data = (void *)1},
 210         {}
 211 };
 212 MODULE_DEVICE_TABLE(of, qcom_rng_of_match);
 213
 214 static struct platform_driver qcom_rng_driver = {
 215         .probe = qcom_rng_probe,
 216         .remove =  qcom_rng_remove,
 217         .driver = {
 218                 .name = KBUILD_MODNAME,
 219                 .of_match_table = of_match_ptr(qcom_rng_of_match),
 220                 .acpi_match_table = ACPI_PTR(qcom_rng_acpi_match),
 221         }
 222 };
 223 module_platform_driver(qcom_rng_driver);
 224
 225 MODULE_ALIAS("platform:" KBUILD_MODNAME);
 226 MODULE_DESCRIPTION("Qualcomm random number generator driver");
 227 MODULE_LICENSE("GPL v2");