1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Generic PowerPC 44x RNG driver 4 * 5 * Copyright 2011 IBM Corporation 6 */ 7 8 #include <linux/module.h> 9 #include <linux/kernel.h> 10 #include <linux/interrupt.h> 11 #include <linux/platform_device.h> 12 #include <linux/hw_random.h> 13 #include <linux/delay.h> 14 #include <linux/of_address.h> 15 #include <linux/of_platform.h> 16 #include <linux/io.h> 17 18 #include "crypto4xx_core.h" 19 #include "crypto4xx_trng.h" 20 #include "crypto4xx_reg_def.h" 21 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 static int ppc4xx_trng_data_present(struct hwrng *rng, int wait) 29 { 30 struct crypto4xx_device *dev = (void *)rng->priv; 31 int busy, i, present = 0; 32 33 for (i = 0; i < 20; i++) { 34 busy = (in_le32(dev->trng_base + PPC4XX_TRNG_STAT) & 35 PPC4XX_TRNG_STAT_B); 36 if (!busy || !wait) { 37 present = 1; 38 break; 39 } 40 udelay(10); 41 } 42 return present; 43 } 44 45 static int ppc4xx_trng_data_read(struct hwrng *rng, u32 *data) 46 { 47 struct crypto4xx_device *dev = (void *)rng->priv; 48 *data = in_le32(dev->trng_base + PPC4XX_TRNG_DATA); 49 return 4; 50 } 51 52 static void ppc4xx_trng_enable(struct crypto4xx_device *dev, bool enable) 53 { 54 u32 device_ctrl; 55 56 device_ctrl = readl(dev->ce_base + CRYPTO4XX_DEVICE_CTRL); 57 if (enable) 58 device_ctrl |= PPC4XX_TRNG_EN; 59 else 60 device_ctrl &= ~PPC4XX_TRNG_EN; 61 writel(device_ctrl, dev->ce_base + CRYPTO4XX_DEVICE_CTRL); 62 } 63 64 static const struct of_device_id ppc4xx_trng_match[] = { 65 { .compatible = "ppc4xx-rng", }, 66 { .compatible = "amcc,ppc460ex-rng", }, 67 { .compatible = "amcc,ppc440epx-rng", }, 68 {}, 69 }; 70 71 void ppc4xx_trng_probe(struct crypto4xx_core_device *core_dev) 72 { 73 struct crypto4xx_device *dev = core_dev->dev; 74 struct device_node *trng = NULL; 75 struct hwrng *rng = NULL; 76 int err; 77 78 /* Find the TRNG device node and map it */ 79 trng = of_find_matching_node(NULL, ppc4xx_trng_match); 80 if (!trng || !of_device_is_available(trng)) { 81 of_node_put(trng); 82 return; 83 } 84 85 dev->trng_base = of_iomap(trng, 0); 86 of_node_put(trng); 87 if (!dev->trng_base) 88 goto err_out; 89 90 rng = kzalloc(sizeof(*rng), GFP_KERNEL); 91 if (!rng) 92 goto err_out; 93 94 rng->name = KBUILD_MODNAME; 95 rng->data_present = ppc4xx_trng_data_present; 96 rng->data_read = ppc4xx_trng_data_read; 97 rng->priv = (unsigned long) dev; 98 core_dev->trng = rng; 99 ppc4xx_trng_enable(dev, true); 100 out_le32(dev->trng_base + PPC4XX_TRNG_CTRL, PPC4XX_TRNG_CTRL_DALM); 101 err = devm_hwrng_register(core_dev->device, core_dev->trng); 102 if (err) { 103 ppc4xx_trng_enable(dev, false); 104 dev_err(core_dev->device, "failed to register hwrng (%d).\n", 105 err); 106 goto err_out; 107 } 108 return; 109 110 err_out: 111 iounmap(dev->trng_base); 112 kfree(rng); 113 dev->trng_base = NULL; 114 core_dev->trng = NULL; 115 } 116 117 void ppc4xx_trng_remove(struct crypto4xx_core_device *core_dev) 118 { 119 if (core_dev && core_dev->trng) { 120 struct crypto4xx_device *dev = core_dev->dev; 121 122 devm_hwrng_unregister(core_dev->device, core_dev->trng); 123 ppc4xx_trng_enable(dev, false); 124 iounmap(dev->trng_base); 125 kfree(core_dev->trng); 126 } 127 } 128 129 MODULE_ALIAS("ppc4xx_rng"); 130