diff options
Diffstat (limited to 'drivers/char/hw_random/amd-rng.c')
| -rw-r--r-- | drivers/char/hw_random/amd-rng.c | 219 |
1 files changed, 219 insertions, 0 deletions
diff --git a/drivers/char/hw_random/amd-rng.c b/drivers/char/hw_random/amd-rng.c new file mode 100644 index 000000000..0555e3838 --- /dev/null +++ b/drivers/char/hw_random/amd-rng.c @@ -0,0 +1,219 @@ +/* + * RNG driver for AMD RNGs + * + * Copyright 2005 (c) MontaVista Software, Inc. + * + * with the majority of the code coming from: + * + * Hardware driver for the Intel/AMD/VIA Random Number Generators (RNG) + * (c) Copyright 2003 Red Hat Inc <jgarzik@redhat.com> + * + * derived from + * + * Hardware driver for the AMD 768 Random Number Generator (RNG) + * (c) Copyright 2001 Red Hat Inc + * + * derived from + * + * Hardware driver for Intel i810 Random Number Generator (RNG) + * Copyright 2000,2001 Jeff Garzik <jgarzik@pobox.com> + * Copyright 2000,2001 Philipp Rumpf <prumpf@mandrakesoft.com> + * + * This file is licensed under the terms of the GNU General Public + * License version 2. This program is licensed "as is" without any + * warranty of any kind, whether express or implied. + */ + +#include <linux/delay.h> +#include <linux/hw_random.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/pci.h> + +#define DRV_NAME "AMD768-HWRNG" + +#define RNGDATA 0x00 +#define RNGDONE 0x04 +#define PMBASE_OFFSET 0xF0 +#define PMBASE_SIZE 8 + +/* + * Data for PCI driver interface + * + * This data only exists for exporting the supported + * PCI ids via MODULE_DEVICE_TABLE. We do not actually + * register a pci_driver, because someone else might one day + * want to register another driver on the same PCI id. + */ +static const struct pci_device_id pci_tbl[] = { + { PCI_VDEVICE(AMD, 0x7443), 0, }, + { PCI_VDEVICE(AMD, 0x746b), 0, }, + { 0, }, /* terminate list */ +}; +MODULE_DEVICE_TABLE(pci, pci_tbl); + +struct amd768_priv { + void __iomem *iobase; + struct pci_dev *pcidev; + u32 pmbase; +}; + +static int amd_rng_read(struct hwrng *rng, void *buf, size_t max, bool wait) +{ + u32 *data = buf; + struct amd768_priv *priv = (struct amd768_priv *)rng->priv; + size_t read = 0; + /* We will wait at maximum one time per read */ + int timeout = max / 4 + 1; + + /* + * RNG data is available when RNGDONE is set to 1 + * New random numbers are generated approximately 128 microseconds + * after RNGDATA is read + */ + while (read < max) { + if (ioread32(priv->iobase + RNGDONE) == 0) { + if (wait) { + /* Delay given by datasheet */ + usleep_range(128, 196); + if (timeout-- == 0) + return read; + } else { + return 0; + } + } else { + *data = ioread32(priv->iobase + RNGDATA); + data++; + read += 4; + } + } + + return read; +} + +static int amd_rng_init(struct hwrng *rng) +{ + struct amd768_priv *priv = (struct amd768_priv *)rng->priv; + u8 rnen; + + pci_read_config_byte(priv->pcidev, 0x40, &rnen); + rnen |= BIT(7); /* RNG on */ + pci_write_config_byte(priv->pcidev, 0x40, rnen); + + pci_read_config_byte(priv->pcidev, 0x41, &rnen); + rnen |= BIT(7); /* PMIO enable */ + pci_write_config_byte(priv->pcidev, 0x41, rnen); + + return 0; +} + +static void amd_rng_cleanup(struct hwrng *rng) +{ + struct amd768_priv *priv = (struct amd768_priv *)rng->priv; + u8 rnen; + + pci_read_config_byte(priv->pcidev, 0x40, &rnen); + rnen &= ~BIT(7); /* RNG off */ + pci_write_config_byte(priv->pcidev, 0x40, rnen); +} + +static struct hwrng amd_rng = { + .name = "amd", + .init = amd_rng_init, + .cleanup = amd_rng_cleanup, + .read = amd_rng_read, +}; + +static int __init amd_rng_mod_init(void) +{ + int err; + struct pci_dev *pdev = NULL; + const struct pci_device_id *ent; + u32 pmbase; + struct amd768_priv *priv; + + for_each_pci_dev(pdev) { + ent = pci_match_id(pci_tbl, pdev); + if (ent) + goto found; + } + /* Device not found. */ + return -ENODEV; + +found: + err = pci_read_config_dword(pdev, 0x58, &pmbase); + if (err) + goto put_dev; + + pmbase &= 0x0000FF00; + if (pmbase == 0) { + err = -EIO; + goto put_dev; + } + + priv = kzalloc(sizeof(*priv), GFP_KERNEL); + if (!priv) { + err = -ENOMEM; + goto put_dev; + } + + if (!request_region(pmbase + PMBASE_OFFSET, PMBASE_SIZE, DRV_NAME)) { + dev_err(&pdev->dev, DRV_NAME " region 0x%x already in use!\n", + pmbase + 0xF0); + err = -EBUSY; + goto out; + } + + priv->iobase = ioport_map(pmbase + PMBASE_OFFSET, PMBASE_SIZE); + if (!priv->iobase) { + pr_err(DRV_NAME "Cannot map ioport\n"); + err = -EINVAL; + goto err_iomap; + } + + amd_rng.priv = (unsigned long)priv; + priv->pmbase = pmbase; + priv->pcidev = pdev; + + pr_info(DRV_NAME " detected\n"); + err = hwrng_register(&amd_rng); + if (err) { + pr_err(DRV_NAME " registering failed (%d)\n", err); + goto err_hwrng; + } + return 0; + +err_hwrng: + ioport_unmap(priv->iobase); +err_iomap: + release_region(pmbase + PMBASE_OFFSET, PMBASE_SIZE); +out: + kfree(priv); +put_dev: + pci_dev_put(pdev); + return err; +} + +static void __exit amd_rng_mod_exit(void) +{ + struct amd768_priv *priv; + + priv = (struct amd768_priv *)amd_rng.priv; + + hwrng_unregister(&amd_rng); + + ioport_unmap(priv->iobase); + + release_region(priv->pmbase + PMBASE_OFFSET, PMBASE_SIZE); + + pci_dev_put(priv->pcidev); + + kfree(priv); +} + +module_init(amd_rng_mod_init); +module_exit(amd_rng_mod_exit); + +MODULE_AUTHOR("The Linux Kernel team"); +MODULE_DESCRIPTION("H/W RNG driver for AMD chipsets"); +MODULE_LICENSE("GPL"); |