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