diff options
Diffstat (limited to 'drivers/char/hw_random/cn10k-rng.c')
| -rw-r--r-- | drivers/char/hw_random/cn10k-rng.c | 184 |
1 files changed, 184 insertions, 0 deletions
diff --git a/drivers/char/hw_random/cn10k-rng.c b/drivers/char/hw_random/cn10k-rng.c new file mode 100644 index 000000000..a01e93077 --- /dev/null +++ b/drivers/char/hw_random/cn10k-rng.c @@ -0,0 +1,184 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Marvell CN10K RVU Hardware Random Number Generator. + * + * Copyright (C) 2021 Marvell. + * + */ + +#include <linux/hw_random.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/pci.h> +#include <linux/pci_ids.h> +#include <linux/delay.h> + +#include <linux/arm-smccc.h> + +/* CSRs */ +#define RNM_CTL_STATUS 0x000 +#define RNM_ENTROPY_STATUS 0x008 +#define RNM_CONST 0x030 +#define RNM_EBG_ENT 0x048 +#define RNM_PF_EBG_HEALTH 0x050 +#define RNM_PF_RANDOM 0x400 +#define RNM_TRNG_RESULT 0x408 + +struct cn10k_rng { + void __iomem *reg_base; + struct hwrng ops; + struct pci_dev *pdev; +}; + +#define PLAT_OCTEONTX_RESET_RNG_EBG_HEALTH_STATE 0xc2000b0f + +static unsigned long reset_rng_health_state(struct cn10k_rng *rng) +{ + struct arm_smccc_res res; + + /* Send SMC service call to reset EBG health state */ + arm_smccc_smc(PLAT_OCTEONTX_RESET_RNG_EBG_HEALTH_STATE, 0, 0, 0, 0, 0, 0, 0, &res); + return res.a0; +} + +static int check_rng_health(struct cn10k_rng *rng) +{ + u64 status; + unsigned long err; + + /* Skip checking health */ + if (!rng->reg_base) + return -ENODEV; + + status = readq(rng->reg_base + RNM_PF_EBG_HEALTH); + if (status & BIT_ULL(20)) { + err = reset_rng_health_state(rng); + if (err) { + dev_err(&rng->pdev->dev, "HWRNG: Health test failed (status=%llx)\n", + status); + dev_err(&rng->pdev->dev, "HWRNG: error during reset (error=%lx)\n", + err); + return -EIO; + } + } + return 0; +} + +static void cn10k_read_trng(struct cn10k_rng *rng, u64 *value) +{ + u64 upper, lower; + + *value = readq(rng->reg_base + RNM_PF_RANDOM); + + /* HW can run out of entropy if large amount random data is read in + * quick succession. Zeros may not be real random data from HW. + */ + if (!*value) { + upper = readq(rng->reg_base + RNM_PF_RANDOM); + lower = readq(rng->reg_base + RNM_PF_RANDOM); + while (!(upper & 0x00000000FFFFFFFFULL)) + upper = readq(rng->reg_base + RNM_PF_RANDOM); + while (!(lower & 0xFFFFFFFF00000000ULL)) + lower = readq(rng->reg_base + RNM_PF_RANDOM); + + *value = (upper & 0xFFFFFFFF00000000) | (lower & 0xFFFFFFFF); + } +} + +static int cn10k_rng_read(struct hwrng *hwrng, void *data, + size_t max, bool wait) +{ + struct cn10k_rng *rng = (struct cn10k_rng *)hwrng->priv; + unsigned int size; + u8 *pos = data; + int err = 0; + u64 value; + + err = check_rng_health(rng); + if (err) + return err; + + size = max; + + while (size >= 8) { + cn10k_read_trng(rng, &value); + + *((u64 *)pos) = value; + size -= 8; + pos += 8; + } + + if (size > 0) { + cn10k_read_trng(rng, &value); + + while (size > 0) { + *pos = (u8)value; + value >>= 8; + size--; + pos++; + } + } + + return max - size; +} + +static int cn10k_rng_probe(struct pci_dev *pdev, const struct pci_device_id *id) +{ + struct cn10k_rng *rng; + int err; + + rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL); + if (!rng) + return -ENOMEM; + + rng->pdev = pdev; + pci_set_drvdata(pdev, rng); + + rng->reg_base = pcim_iomap(pdev, 0, 0); + if (!rng->reg_base) { + dev_err(&pdev->dev, "Error while mapping CSRs, exiting\n"); + return -ENOMEM; + } + + rng->ops.name = devm_kasprintf(&pdev->dev, GFP_KERNEL, + "cn10k-rng-%s", dev_name(&pdev->dev)); + if (!rng->ops.name) + return -ENOMEM; + + rng->ops.read = cn10k_rng_read; + rng->ops.quality = 1000; + rng->ops.priv = (unsigned long)rng; + + reset_rng_health_state(rng); + + err = devm_hwrng_register(&pdev->dev, &rng->ops); + if (err) { + dev_err(&pdev->dev, "Could not register hwrng device.\n"); + return err; + } + + return 0; +} + +static void cn10k_rng_remove(struct pci_dev *pdev) +{ + /* Nothing to do */ +} + +static const struct pci_device_id cn10k_rng_id_table[] = { + { PCI_DEVICE(PCI_VENDOR_ID_CAVIUM, 0xA098) }, /* RNG PF */ + {0,}, +}; + +MODULE_DEVICE_TABLE(pci, cn10k_rng_id_table); + +static struct pci_driver cn10k_rng_driver = { + .name = "cn10k_rng", + .id_table = cn10k_rng_id_table, + .probe = cn10k_rng_probe, + .remove = cn10k_rng_remove, +}; + +module_pci_driver(cn10k_rng_driver); +MODULE_AUTHOR("Sunil Goutham <sgoutham@marvell.com>"); +MODULE_DESCRIPTION("Marvell CN10K HW RNG Driver"); +MODULE_LICENSE("GPL v2"); |