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");