2 * Generic PowerPC 44x RNG driver
4 * Copyright 2011 IBM Corporation
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License as published by the
8 * Free Software Foundation; version 2 of the License.
11 #include <linux/module.h>
12 #include <linux/kernel.h>
13 #include <linux/platform_device.h>
14 #include <linux/hw_random.h>
15 #include <linux/delay.h>
16 #include <linux/of_platform.h>
19 #define PPC4XX_TRNG_DEV_CTRL 0x60080
21 #define PPC4XX_TRNGE 0x00020000
22 #define PPC4XX_TRNG_CTRL 0x0008
23 #define PPC4XX_TRNG_CTRL_DALM 0x20
24 #define PPC4XX_TRNG_STAT 0x0004
25 #define PPC4XX_TRNG_STAT_B 0x1
26 #define PPC4XX_TRNG_DATA 0x0000
28 #define MODULE_NAME "ppc4xx_rng"
30 static int ppc4xx_rng_data_present(struct hwrng *rng, int wait)
32 void __iomem *rng_regs = (void __iomem *) rng->priv;
33 int busy, i, present = 0;
35 for (i = 0; i < 20; i++) {
36 busy = (in_le32(rng_regs + PPC4XX_TRNG_STAT) & PPC4XX_TRNG_STAT_B);
46 static int ppc4xx_rng_data_read(struct hwrng *rng, u32 *data)
48 void __iomem *rng_regs = (void __iomem *) rng->priv;
49 *data = in_le32(rng_regs + PPC4XX_TRNG_DATA);
53 static int ppc4xx_rng_enable(int enable)
55 struct device_node *ctrl;
56 void __iomem *ctrl_reg;
60 /* Find the main crypto device node and map it to turn the TRNG on */
61 ctrl = of_find_compatible_node(NULL, NULL, "amcc,ppc4xx-crypto");
65 ctrl_reg = of_iomap(ctrl, 0);
71 val = in_le32(ctrl_reg + PPC4XX_TRNG_DEV_CTRL);
76 val = val & ~PPC4XX_TRNGE;
78 out_le32(ctrl_reg + PPC4XX_TRNG_DEV_CTRL, val);
87 static struct hwrng ppc4xx_rng = {
89 .data_present = ppc4xx_rng_data_present,
90 .data_read = ppc4xx_rng_data_read,
93 static int ppc4xx_rng_probe(struct platform_device *dev)
95 void __iomem *rng_regs;
98 rng_regs = of_iomap(dev->dev.of_node, 0);
102 err = ppc4xx_rng_enable(1);
106 out_le32(rng_regs + PPC4XX_TRNG_CTRL, PPC4XX_TRNG_CTRL_DALM);
107 ppc4xx_rng.priv = (unsigned long) rng_regs;
109 err = hwrng_register(&ppc4xx_rng);
114 static int ppc4xx_rng_remove(struct platform_device *dev)
116 void __iomem *rng_regs = (void __iomem *) ppc4xx_rng.priv;
118 hwrng_unregister(&ppc4xx_rng);
119 ppc4xx_rng_enable(0);
125 static struct of_device_id ppc4xx_rng_match[] = {
126 { .compatible = "ppc4xx-rng", },
127 { .compatible = "amcc,ppc460ex-rng", },
128 { .compatible = "amcc,ppc440epx-rng", },
132 static struct platform_driver ppc4xx_rng_driver = {
135 .owner = THIS_MODULE,
136 .of_match_table = ppc4xx_rng_match,
138 .probe = ppc4xx_rng_probe,
139 .remove = ppc4xx_rng_remove,
142 module_platform_driver(ppc4xx_rng_driver);
144 MODULE_LICENSE("GPL");
145 MODULE_AUTHOR("Josh Boyer <jwboyer@linux.vnet.ibm.com>");
146 MODULE_DESCRIPTION("HW RNG driver for PPC 4xx processors");