1 // SPDX-License-Identifier: GPL-2.0-only
5 * Joshua Henderson <joshua.henderson@microchip.com>
6 * Copyright (C) 2016 Microchip Technology Inc. All rights reserved.
10 #include <linux/clkdev.h>
11 #include <linux/err.h>
12 #include <linux/hw_random.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
17 #include <linux/of_device.h>
18 #include <linux/platform_device.h>
19 #include <linux/slab.h>
24 #define PRNGCONT BIT(10)
25 #define TRNGMOD BIT(11)
26 #define SEEDLOAD BIT(12)
29 #define RNGNUMGEN1 0x10
30 #define RNGNUMGEN2 0x14
34 #define RCNT_MASK 0x7F
43 * The TRNG can generate up to 24Mbps. This is a timeout that should be safe
44 * enough given the instructions in the loop and that the TRNG may not always
47 #define RNG_TIMEOUT 500
49 static int pic32_rng_read(struct hwrng *rng, void *buf, size_t max,
52 struct pic32_rng *priv = container_of(rng, struct pic32_rng, rng);
55 unsigned int timeout = RNG_TIMEOUT;
58 t = readl(priv->base + RNGRCNT) & RCNT_MASK;
60 /* TRNG value comes through the seed registers */
61 *data = ((u64)readl(priv->base + RNGSEED2) << 32) +
62 readl(priv->base + RNGSEED1);
65 } while (wait && --timeout);
70 static int pic32_rng_probe(struct platform_device *pdev)
72 struct pic32_rng *priv;
77 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
81 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
82 priv->base = devm_ioremap_resource(&pdev->dev, res);
83 if (IS_ERR(priv->base))
84 return PTR_ERR(priv->base);
86 priv->clk = devm_clk_get(&pdev->dev, NULL);
87 if (IS_ERR(priv->clk))
88 return PTR_ERR(priv->clk);
90 ret = clk_prepare_enable(priv->clk);
94 /* enable TRNG in enhanced mode */
96 writel(v, priv->base + RNGCON);
98 priv->rng.name = pdev->name;
99 priv->rng.read = pic32_rng_read;
101 ret = hwrng_register(&priv->rng);
105 platform_set_drvdata(pdev, priv);
110 clk_disable_unprepare(priv->clk);
114 static int pic32_rng_remove(struct platform_device *pdev)
116 struct pic32_rng *rng = platform_get_drvdata(pdev);
118 hwrng_unregister(&rng->rng);
119 writel(0, rng->base + RNGCON);
120 clk_disable_unprepare(rng->clk);
124 static const struct of_device_id pic32_rng_of_match[] = {
125 { .compatible = "microchip,pic32mzda-rng", },
128 MODULE_DEVICE_TABLE(of, pic32_rng_of_match);
130 static struct platform_driver pic32_rng_driver = {
131 .probe = pic32_rng_probe,
132 .remove = pic32_rng_remove,
135 .of_match_table = of_match_ptr(pic32_rng_of_match),
139 module_platform_driver(pic32_rng_driver);
141 MODULE_LICENSE("GPL");
142 MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>");
143 MODULE_DESCRIPTION("Microchip PIC32 RNG Driver");