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
ppc4xx_trng_data_present(struct hwrng * rng,int wait)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
ppc4xx_trng_data_read(struct hwrng * rng,u32 * data)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
ppc4xx_trng_enable(struct crypto4xx_device * dev,bool enable)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
ppc4xx_trng_probe(struct crypto4xx_core_device * core_dev)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
ppc4xx_trng_remove(struct crypto4xx_core_device * core_dev)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