linux/drivers/char/hw_random/amd-rng.c
Prarit Bhargava 69db700931 hwrng: amd - Revert managed API changes
After commit 31b2a73c9c ("hwrng: amd - Migrate to managed API"), the
amd-rng driver uses devres with pci_dev->dev to keep track of resources,
but does not actually register a PCI driver.  This results in the
following issues:

1. The message

WARNING: CPU: 2 PID: 621 at drivers/base/dd.c:349 driver_probe_device+0x38c

is output when the i2c_amd756 driver loads and attempts to register a PCI
driver.  The PCI & device subsystems assume that no resources have been
registered for the device, and the WARN_ON() triggers since amd-rng has
already do so.

2.  The driver leaks memory because the driver does not attach to a
device.  The driver only uses the PCI device as a reference.   devm_*()
functions will release resources on driver detach, which the amd-rng
driver will never do.  As a result,

3.  The driver cannot be reloaded because there is always a use of the
ioport and region after the first load of the driver.

Revert the changes made by 31b2a73c9c ("hwrng: amd - Migrate to managed
API").

Cc: <stable@vger.kernel.org>
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Fixes: 31b2a73c9c ("hwrng: amd - Migrate to managed API").
Cc: Matt Mackall <mpm@selenic.com>
Cc: Corentin LABBE <clabbe.montjoie@gmail.com>
Cc: PrasannaKumar Muralidharan <prasannatsmkumar@gmail.com>
Cc: Wei Yongjun <weiyongjun1@huawei.com>
Cc: linux-crypto@vger.kernel.org
Cc: linux-geode@lists.infradead.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2017-03-16 17:43:10 +08:00

212 lines
4.7 KiB
C

/*
* 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 mod_init(void)
{
int err = -ENODEV;
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)
return err;
pmbase &= 0x0000FF00;
if (pmbase == 0)
return -EIO;
priv = kzalloc(sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
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);
return err;
}
static void __exit 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);
kfree(priv);
}
module_init(mod_init);
module_exit(mod_exit);
MODULE_AUTHOR("The Linux Kernel team");
MODULE_DESCRIPTION("H/W RNG driver for AMD chipsets");
MODULE_LICENSE("GPL");