4 * Joshua Henderson <joshua.henderson@microchip.com>
5 * Copyright (C) 2016 Microchip Technology Inc. All rights reserved.
7 * This program is free software; you can distribute it and/or modify it
8 * under the terms of the GNU General Public License (Version 2) as
9 * published by the Free Software Foundation.
11 * This program is distributed in the hope it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 #include <linux/clk.h>
18 #include <linux/clkdev.h>
19 #include <linux/err.h>
20 #include <linux/hw_random.h>
22 #include <linux/kernel.h>
23 #include <linux/module.h>
25 #include <linux/of_device.h>
26 #include <linux/platform_device.h>
27 #include <linux/slab.h>
32 #define PRNGCONT BIT(10)
33 #define TRNGMOD BIT(11)
34 #define SEEDLOAD BIT(12)
37 #define RNGNUMGEN1 0x10
38 #define RNGNUMGEN2 0x14
42 #define RCNT_MASK 0x7F
51 * The TRNG can generate up to 24Mbps. This is a timeout that should be safe
52 * enough given the instructions in the loop and that the TRNG may not always
55 #define RNG_TIMEOUT 500
57 static int pic32_rng_read(struct hwrng *rng, void *buf, size_t max,
60 struct pic32_rng *priv = container_of(rng, struct pic32_rng, rng);
63 unsigned int timeout = RNG_TIMEOUT;
66 t = readl(priv->base + RNGRCNT) & RCNT_MASK;
68 /* TRNG value comes through the seed registers */
69 *data = ((u64)readl(priv->base + RNGSEED2) << 32) +
70 readl(priv->base + RNGSEED1);
73 } while (wait && --timeout);
78 static int pic32_rng_probe(struct platform_device *pdev)
80 struct pic32_rng *priv;
85 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
89 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
90 priv->base = devm_ioremap_resource(&pdev->dev, res);
91 if (IS_ERR(priv->base))
92 return PTR_ERR(priv->base);
94 priv->clk = devm_clk_get(&pdev->dev, NULL);
95 if (IS_ERR(priv->clk))
96 return PTR_ERR(priv->clk);
98 ret = clk_prepare_enable(priv->clk);
102 /* enable TRNG in enhanced mode */
103 v = TRNGEN | TRNGMOD;
104 writel(v, priv->base + RNGCON);
106 priv->rng.name = pdev->name;
107 priv->rng.read = pic32_rng_read;
109 ret = hwrng_register(&priv->rng);
113 platform_set_drvdata(pdev, priv);
118 clk_disable_unprepare(priv->clk);
122 static int pic32_rng_remove(struct platform_device *pdev)
124 struct pic32_rng *rng = platform_get_drvdata(pdev);
126 hwrng_unregister(&rng->rng);
127 writel(0, rng->base + RNGCON);
128 clk_disable_unprepare(rng->clk);
132 static const struct of_device_id pic32_rng_of_match[] = {
133 { .compatible = "microchip,pic32mzda-rng", },
136 MODULE_DEVICE_TABLE(of, pic32_rng_of_match);
138 static struct platform_driver pic32_rng_driver = {
139 .probe = pic32_rng_probe,
140 .remove = pic32_rng_remove,
143 .of_match_table = of_match_ptr(pic32_rng_of_match),
147 module_platform_driver(pic32_rng_driver);
149 MODULE_LICENSE("GPL");
150 MODULE_AUTHOR("Joshua Henderson <joshua.henderson@microchip.com>");
151 MODULE_DESCRIPTION("Microchip PIC32 RNG Driver");