crypto/amcc/crypto4xx_trng.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Generic PowerPC 44x RNG driver
0004  *
0005  * Copyright 2011 IBM Corporation
0006  */
0007
0008 #include <linux/module.h>
0009 #include <linux/kernel.h>
0010 #include <linux/interrupt.h>
0011 #include <linux/platform_device.h>
0012 #include <linux/hw_random.h>
0013 #include <linux/delay.h>
0014 #include <linux/of_address.h>
0015 #include <linux/of_platform.h>
0016 #include <linux/io.h>
0017
0018 #include "crypto4xx_core.h"
0019 #include "crypto4xx_trng.h"
0020 #include "crypto4xx_reg_def.h"
0021
0022 #define PPC4XX_TRNG_CTRL    0x0008
0023 #define PPC4XX_TRNG_CTRL_DALM   0x20
0024 #define PPC4XX_TRNG_STAT    0x0004
0025 #define PPC4XX_TRNG_STAT_B  0x1
0026 #define PPC4XX_TRNG_DATA    0x0000
0027
0028 static int ppc4xx_trng_data_present(struct hwrng *rng, int wait)
0029 {
0030     struct crypto4xx_device *dev = (void *)rng->priv;
0031     int busy, i, present = 0;
0032
0033     for (i = 0; i < 20; i++) {
0034         busy = (in_le32(dev->trng_base + PPC4XX_TRNG_STAT) &
0035             PPC4XX_TRNG_STAT_B);
0036         if (!busy || !wait) {
0037             present = 1;
0038             break;
0039         }
0040         udelay(10);
0041     }
0042     return present;
0043 }
0044
0045 static int ppc4xx_trng_data_read(struct hwrng *rng, u32 *data)
0046 {
0047     struct crypto4xx_device *dev = (void *)rng->priv;
0048     *data = in_le32(dev->trng_base + PPC4XX_TRNG_DATA);
0049     return 4;
0050 }
0051
0052 static void ppc4xx_trng_enable(struct crypto4xx_device *dev, bool enable)
0053 {
0054     u32 device_ctrl;
0055
0056     device_ctrl = readl(dev->ce_base + CRYPTO4XX_DEVICE_CTRL);
0057     if (enable)
0058         device_ctrl |= PPC4XX_TRNG_EN;
0059     else
0060         device_ctrl &= ~PPC4XX_TRNG_EN;
0061     writel(device_ctrl, dev->ce_base + CRYPTO4XX_DEVICE_CTRL);
0062 }
0063
0064 static const struct of_device_id ppc4xx_trng_match[] = {
0065     { .compatible = "ppc4xx-rng", },
0066     { .compatible = "amcc,ppc460ex-rng", },
0067     { .compatible = "amcc,ppc440epx-rng", },
0068     {},
0069 };
0070
0071 void ppc4xx_trng_probe(struct crypto4xx_core_device *core_dev)
0072 {
0073     struct crypto4xx_device *dev = core_dev->dev;
0074     struct device_node *trng = NULL;
0075     struct hwrng *rng = NULL;
0076     int err;
0077
0078     /* Find the TRNG device node and map it */
0079     trng = of_find_matching_node(NULL, ppc4xx_trng_match);
0080     if (!trng || !of_device_is_available(trng)) {
0081         of_node_put(trng);
0082         return;
0083     }
0084
0085     dev->trng_base = of_iomap(trng, 0);
0086     of_node_put(trng);
0087     if (!dev->trng_base)
0088         goto err_out;
0089
0090     rng = kzalloc(sizeof(*rng), GFP_KERNEL);
0091     if (!rng)
0092         goto err_out;
0093
0094     rng->name = KBUILD_MODNAME;
0095     rng->data_present = ppc4xx_trng_data_present;
0096     rng->data_read = ppc4xx_trng_data_read;
0097     rng->priv = (unsigned long) dev;
0098     core_dev->trng = rng;
0099     ppc4xx_trng_enable(dev, true);
0100     out_le32(dev->trng_base + PPC4XX_TRNG_CTRL, PPC4XX_TRNG_CTRL_DALM);
0101     err = devm_hwrng_register(core_dev->device, core_dev->trng);
0102     if (err) {
0103         ppc4xx_trng_enable(dev, false);
0104         dev_err(core_dev->device, "failed to register hwrng (%d).\n",
0105             err);
0106         goto err_out;
0107     }
0108     return;
0109
0110 err_out:
0111     iounmap(dev->trng_base);
0112     kfree(rng);
0113     dev->trng_base = NULL;
0114     core_dev->trng = NULL;
0115 }
0116
0117 void ppc4xx_trng_remove(struct crypto4xx_core_device *core_dev)
0118 {
0119     if (core_dev && core_dev->trng) {
0120         struct crypto4xx_device *dev = core_dev->dev;
0121
0122         devm_hwrng_unregister(core_dev->device, core_dev->trng);
0123         ppc4xx_trng_enable(dev, false);
0124         iounmap(dev->trng_base);
0125         kfree(core_dev->trng);
0126     }
0127 }
0128
0129 MODULE_ALIAS("ppc4xx_rng");