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/interrupt.h> 14 #include <linux/platform_device.h> 15 #include <linux/hw_random.h> 16 #include <linux/delay.h> 17 #include <linux/of_address.h> 18 #include <linux/of_platform.h> 19 #include <linux/io.h> 20 21 #include "crypto4xx_core.h" 22 #include "crypto4xx_trng.h" 23 #include "crypto4xx_reg_def.h" 24 25 #define PPC4XX_TRNG_CTRL 0x0008 26 #define PPC4XX_TRNG_CTRL_DALM 0x20 27 #define PPC4XX_TRNG_STAT 0x0004 28 #define PPC4XX_TRNG_STAT_B 0x1 29 #define PPC4XX_TRNG_DATA 0x0000 30 31 static int ppc4xx_trng_data_present(struct hwrng *rng, int wait) 32 { 33 struct crypto4xx_device *dev = (void *)rng->priv; 34 int busy, i, present = 0; 35 36 for (i = 0; i < 20; i++) { 37 busy = (in_le32(dev->trng_base + PPC4XX_TRNG_STAT) & 38 PPC4XX_TRNG_STAT_B); 39 if (!busy || !wait) { 40 present = 1; 41 break; 42 } 43 udelay(10); 44 } 45 return present; 46 } 47 48 static int ppc4xx_trng_data_read(struct hwrng *rng, u32 *data) 49 { 50 struct crypto4xx_device *dev = (void *)rng->priv; 51 *data = in_le32(dev->trng_base + PPC4XX_TRNG_DATA); 52 return 4; 53 } 54 55 static void ppc4xx_trng_enable(struct crypto4xx_device *dev, bool enable) 56 { 57 u32 device_ctrl; 58 59 device_ctrl = readl(dev->ce_base + CRYPTO4XX_DEVICE_CTRL); 60 if (enable) 61 device_ctrl |= PPC4XX_TRNG_EN; 62 else 63 device_ctrl &= ~PPC4XX_TRNG_EN; 64 writel(device_ctrl, dev->ce_base + CRYPTO4XX_DEVICE_CTRL); 65 } 66 67 static const struct of_device_id ppc4xx_trng_match[] = { 68 { .compatible = "ppc4xx-rng", }, 69 { .compatible = "amcc,ppc460ex-rng", }, 70 { .compatible = "amcc,ppc440epx-rng", }, 71 {}, 72 }; 73 74 void ppc4xx_trng_probe(struct crypto4xx_core_device *core_dev) 75 { 76 struct crypto4xx_device *dev = core_dev->dev; 77 struct device_node *trng = NULL; 78 struct hwrng *rng = NULL; 79 int err; 80 81 /* Find the TRNG device node and map it */ 82 trng = of_find_matching_node(NULL, ppc4xx_trng_match); 83 if (!trng || !of_device_is_available(trng)) 84 return; 85 86 dev->trng_base = of_iomap(trng, 0); 87 of_node_put(trng); 88 if (!dev->trng_base) 89 goto err_out; 90 91 rng = kzalloc(sizeof(*rng), GFP_KERNEL); 92 if (!rng) 93 goto err_out; 94 95 rng->name = KBUILD_MODNAME; 96 rng->data_present = ppc4xx_trng_data_present; 97 rng->data_read = ppc4xx_trng_data_read; 98 rng->priv = (unsigned long) dev; 99 core_dev->trng = rng; 100 ppc4xx_trng_enable(dev, true); 101 out_le32(dev->trng_base + PPC4XX_TRNG_CTRL, PPC4XX_TRNG_CTRL_DALM); 102 err = devm_hwrng_register(core_dev->device, core_dev->trng); 103 if (err) { 104 ppc4xx_trng_enable(dev, false); 105 dev_err(core_dev->device, "failed to register hwrng (%d).\n", 106 err); 107 goto err_out; 108 } 109 return; 110 111 err_out: 112 of_node_put(trng); 113 iounmap(dev->trng_base); 114 kfree(rng); 115 dev->trng_base = NULL; 116 core_dev->trng = NULL; 117 } 118 119 void ppc4xx_trng_remove(struct crypto4xx_core_device *core_dev) 120 { 121 if (core_dev && core_dev->trng) { 122 struct crypto4xx_device *dev = core_dev->dev; 123 124 devm_hwrng_unregister(core_dev->device, core_dev->trng); 125 ppc4xx_trng_enable(dev, false); 126 iounmap(dev->trng_base); 127 kfree(core_dev->trng); 128 } 129 } 130 131 MODULE_ALIAS("ppc4xx_rng"); 132