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