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
28static 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
45static 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
52static 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
64static 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
71void 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
110err_out:
111	iounmap(dev->trng_base);
112	kfree(rng);
113	dev->trng_base = NULL;
114	core_dev->trng = NULL;
115}
116
117void 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
129MODULE_ALIAS("ppc4xx_rng");
130