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| 1 | /* |
| 2 | * Generic PowerPC 44x RNG driver |
| 3 | * |
| 4 | * Copyright 2011 IBM Corporation |
| 5 | * |
| 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. |
| 9 | */ |
| 10 | |
| 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> |
| 17 | #include <asm/io.h> |
| 18 | |
| 19 | #define PPC4XX_TRNG_DEV_CTRL 0x60080 |
| 20 | |
| 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 |
| 27 | |
| 28 | #define MODULE_NAME "ppc4xx_rng" |
| 29 | |
| 30 | static int ppc4xx_rng_data_present(struct hwrng *rng, int wait) |
| 31 | { |
| 32 | void __iomem *rng_regs = (void __iomem *) rng->priv; |
| 33 | int busy, i, present = 0; |
| 34 | |
| 35 | for (i = 0; i < 20; i++) { |
| 36 | busy = (in_le32(rng_regs + PPC4XX_TRNG_STAT) & PPC4XX_TRNG_STAT_B); |
| 37 | if (!busy || !wait) { |
| 38 | present = 1; |
| 39 | break; |
| 40 | } |
| 41 | udelay(10); |
| 42 | } |
| 43 | return present; |
| 44 | } |
| 45 | |
| 46 | static int ppc4xx_rng_data_read(struct hwrng *rng, u32 *data) |
| 47 | { |
| 48 | void __iomem *rng_regs = (void __iomem *) rng->priv; |
| 49 | *data = in_le32(rng_regs + PPC4XX_TRNG_DATA); |
| 50 | return 4; |
| 51 | } |
| 52 | |
| 53 | static int ppc4xx_rng_enable(int enable) |
| 54 | { |
| 55 | struct device_node *ctrl; |
| 56 | void __iomem *ctrl_reg; |
| 57 | int err = 0; |
| 58 | u32 val; |
| 59 | |
| 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"); |
| 62 | if (!ctrl) |
| 63 | return -ENODEV; |
| 64 | |
| 65 | ctrl_reg = of_iomap(ctrl, 0); |
| 66 | if (!ctrl_reg) { |
| 67 | err = -ENODEV; |
| 68 | goto out; |
| 69 | } |
| 70 | |
| 71 | val = in_le32(ctrl_reg + PPC4XX_TRNG_DEV_CTRL); |
| 72 | |
| 73 | if (enable) |
| 74 | val |= PPC4XX_TRNGE; |
| 75 | else |
| 76 | val = val & ~PPC4XX_TRNGE; |
| 77 | |
| 78 | out_le32(ctrl_reg + PPC4XX_TRNG_DEV_CTRL, val); |
| 79 | iounmap(ctrl_reg); |
| 80 | |
| 81 | out: |
| 82 | of_node_put(ctrl); |
| 83 | |
| 84 | return err; |
| 85 | } |
| 86 | |
| 87 | static struct hwrng ppc4xx_rng = { |
| 88 | .name = MODULE_NAME, |
| 89 | .data_present = ppc4xx_rng_data_present, |
| 90 | .data_read = ppc4xx_rng_data_read, |
| 91 | }; |
| 92 | |
| 93 | static int ppc4xx_rng_probe(struct platform_device *dev) |
| 94 | { |
| 95 | void __iomem *rng_regs; |
| 96 | int err = 0; |
| 97 | |
| 98 | rng_regs = of_iomap(dev->dev.of_node, 0); |
| 99 | if (!rng_regs) |
| 100 | return -ENODEV; |
| 101 | |
| 102 | err = ppc4xx_rng_enable(1); |
| 103 | if (err) |
| 104 | return err; |
| 105 | |
| 106 | out_le32(rng_regs + PPC4XX_TRNG_CTRL, PPC4XX_TRNG_CTRL_DALM); |
| 107 | ppc4xx_rng.priv = (unsigned long) rng_regs; |
| 108 | |
| 109 | err = hwrng_register(&ppc4xx_rng); |
| 110 | |
| 111 | return err; |
| 112 | } |
| 113 | |
| 114 | static int ppc4xx_rng_remove(struct platform_device *dev) |
| 115 | { |
| 116 | void __iomem *rng_regs = (void __iomem *) ppc4xx_rng.priv; |
| 117 | |
| 118 | hwrng_unregister(&ppc4xx_rng); |
| 119 | ppc4xx_rng_enable(0); |
| 120 | iounmap(rng_regs); |
| 121 | |
| 122 | return 0; |
| 123 | } |
| 124 | |
| 125 | static struct of_device_id ppc4xx_rng_match[] = { |
| 126 | { .compatible = "ppc4xx-rng", }, |
| 127 | { .compatible = "amcc,ppc460ex-rng", }, |
| 128 | { .compatible = "amcc,ppc440epx-rng", }, |
| 129 | {}, |
| 130 | }; |
| 131 | |
| 132 | static struct platform_driver ppc4xx_rng_driver = { |
| 133 | .driver = { |
| 134 | .name = MODULE_NAME, |
| 135 | .owner = THIS_MODULE, |
| 136 | .of_match_table = ppc4xx_rng_match, |
| 137 | }, |
| 138 | .probe = ppc4xx_rng_probe, |
| 139 | .remove = ppc4xx_rng_remove, |
| 140 | }; |
| 141 | |
| 142 | module_platform_driver(ppc4xx_rng_driver); |
| 143 | |
| 144 | MODULE_LICENSE("GPL"); |
| 145 | MODULE_AUTHOR("Josh Boyer <jwboyer@linux.vnet.ibm.com>"); |
| 146 | MODULE_DESCRIPTION("HW RNG driver for PPC 4xx processors"); |
| 147 |
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