char/hw_random/ingenic-trng.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Ingenic True Random Number Generator driver
0004  * Copyright (c) 2019 漆鹏振 (Qi Pengzhen) <aric.pzqi@ingenic.com>
0005  * Copyright (c) 2020 周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>
0006  */
0007
0008 #include <linux/clk.h>
0009 #include <linux/err.h>
0010 #include <linux/kernel.h>
0011 #include <linux/hw_random.h>
0012 #include <linux/io.h>
0013 #include <linux/iopoll.h>
0014 #include <linux/module.h>
0015 #include <linux/of_device.h>
0016 #include <linux/platform_device.h>
0017 #include <linux/slab.h>
0018
0019 /* DTRNG register offsets */
0020 #define TRNG_REG_CFG_OFFSET         0x00
0021 #define TRNG_REG_RANDOMNUM_OFFSET   0x04
0022 #define TRNG_REG_STATUS_OFFSET      0x08
0023
0024 /* bits within the CFG register */
0025 #define CFG_RDY_CLR                 BIT(12)
0026 #define CFG_INT_MASK                BIT(11)
0027 #define CFG_GEN_EN                  BIT(0)
0028
0029 /* bits within the STATUS register */
0030 #define STATUS_RANDOM_RDY           BIT(0)
0031
0032 struct ingenic_trng {
0033     void __iomem *base;
0034     struct clk *clk;
0035     struct hwrng rng;
0036 };
0037
0038 static int ingenic_trng_init(struct hwrng *rng)
0039 {
0040     struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
0041     unsigned int ctrl;
0042
0043     ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
0044     ctrl |= CFG_GEN_EN;
0045     writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
0046
0047     return 0;
0048 }
0049
0050 static void ingenic_trng_cleanup(struct hwrng *rng)
0051 {
0052     struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
0053     unsigned int ctrl;
0054
0055     ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
0056     ctrl &= ~CFG_GEN_EN;
0057     writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
0058 }
0059
0060 static int ingenic_trng_read(struct hwrng *rng, void *buf, size_t max, bool wait)
0061 {
0062     struct ingenic_trng *trng = container_of(rng, struct ingenic_trng, rng);
0063     u32 *data = buf;
0064     u32 status;
0065     int ret;
0066
0067     ret = readl_poll_timeout(trng->base + TRNG_REG_STATUS_OFFSET, status,
0068                  status & STATUS_RANDOM_RDY, 10, 1000);
0069     if (ret == -ETIMEDOUT) {
0070         pr_err("%s: Wait for DTRNG data ready timeout\n", __func__);
0071         return ret;
0072     }
0073
0074     *data = readl(trng->base + TRNG_REG_RANDOMNUM_OFFSET);
0075
0076     return 4;
0077 }
0078
0079 static int ingenic_trng_probe(struct platform_device *pdev)
0080 {
0081     struct ingenic_trng *trng;
0082     int ret;
0083
0084     trng = devm_kzalloc(&pdev->dev, sizeof(*trng), GFP_KERNEL);
0085     if (!trng)
0086         return -ENOMEM;
0087
0088     trng->base = devm_platform_ioremap_resource(pdev, 0);
0089     if (IS_ERR(trng->base)) {
0090         pr_err("%s: Failed to map DTRNG registers\n", __func__);
0091         ret = PTR_ERR(trng->base);
0092         return PTR_ERR(trng->base);
0093     }
0094
0095     trng->clk = devm_clk_get(&pdev->dev, NULL);
0096     if (IS_ERR(trng->clk)) {
0097         ret = PTR_ERR(trng->clk);
0098         pr_crit("%s: Cannot get DTRNG clock\n", __func__);
0099         return PTR_ERR(trng->clk);
0100     }
0101
0102     ret = clk_prepare_enable(trng->clk);
0103     if (ret) {
0104         pr_crit("%s: Unable to enable DTRNG clock\n", __func__);
0105         return ret;
0106     }
0107
0108     trng->rng.name = pdev->name;
0109     trng->rng.init = ingenic_trng_init;
0110     trng->rng.cleanup = ingenic_trng_cleanup;
0111     trng->rng.read = ingenic_trng_read;
0112
0113     ret = hwrng_register(&trng->rng);
0114     if (ret) {
0115         dev_err(&pdev->dev, "Failed to register hwrng\n");
0116         goto err_unprepare_clk;
0117     }
0118
0119     platform_set_drvdata(pdev, trng);
0120
0121     dev_info(&pdev->dev, "Ingenic DTRNG driver registered\n");
0122     return 0;
0123
0124 err_unprepare_clk:
0125     clk_disable_unprepare(trng->clk);
0126     return ret;
0127 }
0128
0129 static int ingenic_trng_remove(struct platform_device *pdev)
0130 {
0131     struct ingenic_trng *trng = platform_get_drvdata(pdev);
0132     unsigned int ctrl;
0133
0134     hwrng_unregister(&trng->rng);
0135
0136     ctrl = readl(trng->base + TRNG_REG_CFG_OFFSET);
0137     ctrl &= ~CFG_GEN_EN;
0138     writel(ctrl, trng->base + TRNG_REG_CFG_OFFSET);
0139
0140     clk_disable_unprepare(trng->clk);
0141
0142     return 0;
0143 }
0144
0145 static const struct of_device_id ingenic_trng_of_match[] = {
0146     { .compatible = "ingenic,x1830-dtrng" },
0147     { /* sentinel */ }
0148 };
0149 MODULE_DEVICE_TABLE(of, ingenic_trng_of_match);
0150
0151 static struct platform_driver ingenic_trng_driver = {
0152     .probe      = ingenic_trng_probe,
0153     .remove     = ingenic_trng_remove,
0154     .driver     = {
0155         .name   = "ingenic-trng",
0156         .of_match_table = ingenic_trng_of_match,
0157     },
0158 };
0159
0160 module_platform_driver(ingenic_trng_driver);
0161
0162 MODULE_LICENSE("GPL");
0163 MODULE_AUTHOR("漆鹏振 (Qi Pengzhen) <aric.pzqi@ingenic.com>");
0164 MODULE_AUTHOR("周琰杰 (Zhou Yanjie) <zhouyanjie@wanyeetech.com>");
0165 MODULE_DESCRIPTION("Ingenic True Random Number Generator driver");