diff options
Diffstat (limited to 'drivers/char/hw_random/cavium-rng-vf.c')
| -rw-r--r-- | drivers/char/hw_random/cavium-rng-vf.c | 270 |
1 files changed, 270 insertions, 0 deletions
diff --git a/drivers/char/hw_random/cavium-rng-vf.c b/drivers/char/hw_random/cavium-rng-vf.c new file mode 100644 index 000000000..7c55f4cf4 --- /dev/null +++ b/drivers/char/hw_random/cavium-rng-vf.c @@ -0,0 +1,270 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Hardware Random Number Generator support. + * Cavium Thunder, Marvell OcteonTx/Tx2 processor families. + * + * Copyright (C) 2016 Cavium, Inc. + */ + +#include <linux/hw_random.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/pci.h> +#include <linux/pci_ids.h> + +#include <asm/arch_timer.h> + +/* PCI device IDs */ +#define PCI_DEVID_CAVIUM_RNG_PF 0xA018 +#define PCI_DEVID_CAVIUM_RNG_VF 0xA033 + +#define HEALTH_STATUS_REG 0x38 + +/* RST device info */ +#define PCI_DEVICE_ID_RST_OTX2 0xA085 +#define RST_BOOT_REG 0x1600ULL +#define CLOCK_BASE_RATE 50000000ULL +#define MSEC_TO_NSEC(x) (x * 1000000) + +struct cavium_rng { + struct hwrng ops; + void __iomem *result; + void __iomem *pf_regbase; + struct pci_dev *pdev; + u64 clock_rate; + u64 prev_error; + u64 prev_time; +}; + +static inline bool is_octeontx(struct pci_dev *pdev) +{ + if (midr_is_cpu_model_range(read_cpuid_id(), MIDR_THUNDERX_83XX, + MIDR_CPU_VAR_REV(0, 0), + MIDR_CPU_VAR_REV(3, 0)) || + midr_is_cpu_model_range(read_cpuid_id(), MIDR_THUNDERX_81XX, + MIDR_CPU_VAR_REV(0, 0), + MIDR_CPU_VAR_REV(3, 0)) || + midr_is_cpu_model_range(read_cpuid_id(), MIDR_THUNDERX, + MIDR_CPU_VAR_REV(0, 0), + MIDR_CPU_VAR_REV(3, 0))) + return true; + + return false; +} + +static u64 rng_get_coprocessor_clkrate(void) +{ + u64 ret = CLOCK_BASE_RATE * 16; /* Assume 800Mhz as default */ + struct pci_dev *pdev; + void __iomem *base; + + pdev = pci_get_device(PCI_VENDOR_ID_CAVIUM, + PCI_DEVICE_ID_RST_OTX2, NULL); + if (!pdev) + goto error; + + base = pci_ioremap_bar(pdev, 0); + if (!base) + goto error_put_pdev; + + /* RST: PNR_MUL * 50Mhz gives clockrate */ + ret = CLOCK_BASE_RATE * ((readq(base + RST_BOOT_REG) >> 33) & 0x3F); + + iounmap(base); + +error_put_pdev: + pci_dev_put(pdev); + +error: + return ret; +} + +static int check_rng_health(struct cavium_rng *rng) +{ + u64 cur_err, cur_time; + u64 status, cycles; + u64 time_elapsed; + + + /* Skip checking health for OcteonTx */ + if (!rng->pf_regbase) + return 0; + + status = readq(rng->pf_regbase + HEALTH_STATUS_REG); + if (status & BIT_ULL(0)) { + dev_err(&rng->pdev->dev, "HWRNG: Startup health test failed\n"); + return -EIO; + } + + cycles = status >> 1; + if (!cycles) + return 0; + + cur_time = arch_timer_read_counter(); + + /* RNM_HEALTH_STATUS[CYCLES_SINCE_HEALTH_FAILURE] + * Number of coprocessor cycles times 2 since the last failure. + * This field doesn't get cleared/updated until another failure. + */ + cycles = cycles / 2; + cur_err = (cycles * 1000000000) / rng->clock_rate; /* In nanosec */ + + /* Ignore errors that happenned a long time ago, these + * are most likely false positive errors. + */ + if (cur_err > MSEC_TO_NSEC(10)) { + rng->prev_error = 0; + rng->prev_time = 0; + return 0; + } + + if (rng->prev_error) { + /* Calculate time elapsed since last error + * '1' tick of CNTVCT is 10ns, since it runs at 100Mhz. + */ + time_elapsed = (cur_time - rng->prev_time) * 10; + time_elapsed += rng->prev_error; + + /* Check if current error is a new one or the old one itself. + * If error is a new one then consider there is a persistent + * issue with entropy, declare hardware failure. + */ + if (cur_err < time_elapsed) { + dev_err(&rng->pdev->dev, "HWRNG failure detected\n"); + rng->prev_error = cur_err; + rng->prev_time = cur_time; + return -EIO; + } + } + + rng->prev_error = cur_err; + rng->prev_time = cur_time; + return 0; +} + +/* Read data from the RNG unit */ +static int cavium_rng_read(struct hwrng *rng, void *dat, size_t max, bool wait) +{ + struct cavium_rng *p = container_of(rng, struct cavium_rng, ops); + unsigned int size = max; + int err = 0; + + err = check_rng_health(p); + if (err) + return err; + + while (size >= 8) { + *((u64 *)dat) = readq(p->result); + size -= 8; + dat += 8; + } + while (size > 0) { + *((u8 *)dat) = readb(p->result); + size--; + dat++; + } + return max; +} + +static int cavium_map_pf_regs(struct cavium_rng *rng) +{ + struct pci_dev *pdev; + + /* Health status is not supported on 83xx, skip mapping PF CSRs */ + if (is_octeontx(rng->pdev)) { + rng->pf_regbase = NULL; + return 0; + } + + pdev = pci_get_device(PCI_VENDOR_ID_CAVIUM, + PCI_DEVID_CAVIUM_RNG_PF, NULL); + if (!pdev) { + pr_err("Cannot find RNG PF device\n"); + return -EIO; + } + + rng->pf_regbase = ioremap(pci_resource_start(pdev, 0), + pci_resource_len(pdev, 0)); + if (!rng->pf_regbase) { + dev_err(&pdev->dev, "Failed to map PF CSR region\n"); + pci_dev_put(pdev); + return -ENOMEM; + } + + pci_dev_put(pdev); + + /* Get co-processor clock rate */ + rng->clock_rate = rng_get_coprocessor_clkrate(); + + return 0; +} + +/* Map Cavium RNG to an HWRNG object */ +static int cavium_rng_probe_vf(struct pci_dev *pdev, + const struct pci_device_id *id) +{ + struct cavium_rng *rng; + int ret; + + rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL); + if (!rng) + return -ENOMEM; + + rng->pdev = pdev; + + /* Map the RNG result */ + rng->result = pcim_iomap(pdev, 0, 0); + if (!rng->result) { + dev_err(&pdev->dev, "Error iomap failed retrieving result.\n"); + return -ENOMEM; + } + + rng->ops.name = devm_kasprintf(&pdev->dev, GFP_KERNEL, + "cavium-rng-%s", dev_name(&pdev->dev)); + if (!rng->ops.name) + return -ENOMEM; + + rng->ops.read = cavium_rng_read; + rng->ops.quality = 1000; + + pci_set_drvdata(pdev, rng); + + /* Health status is available only at PF, hence map PF registers. */ + ret = cavium_map_pf_regs(rng); + if (ret) + return ret; + + ret = devm_hwrng_register(&pdev->dev, &rng->ops); + if (ret) { + dev_err(&pdev->dev, "Error registering device as HWRNG.\n"); + return ret; + } + + return 0; +} + +/* Remove the VF */ +static void cavium_rng_remove_vf(struct pci_dev *pdev) +{ + struct cavium_rng *rng; + + rng = pci_get_drvdata(pdev); + iounmap(rng->pf_regbase); +} + +static const struct pci_device_id cavium_rng_vf_id_table[] = { + { PCI_DEVICE(PCI_VENDOR_ID_CAVIUM, PCI_DEVID_CAVIUM_RNG_VF) }, + { 0, } +}; +MODULE_DEVICE_TABLE(pci, cavium_rng_vf_id_table); + +static struct pci_driver cavium_rng_vf_driver = { + .name = "cavium_rng_vf", + .id_table = cavium_rng_vf_id_table, + .probe = cavium_rng_probe_vf, + .remove = cavium_rng_remove_vf, +}; +module_pci_driver(cavium_rng_vf_driver); + +MODULE_AUTHOR("Omer Khaliq <okhaliq@caviumnetworks.com>"); +MODULE_LICENSE("GPL v2"); |