Re: [patch 3/9] Add Intel HW RNG driver

[Sergey Vlasov]

On Fri, May 12, 2006 at 12:35:25PM +0200, Michael Buesch wrote:
> Index: hwrng/drivers/char/hw_random/intel-rng.c
> ===================================================================
> --- /dev/null	1970-01-01 00:00:00.000000000 +0000
> +++ hwrng/drivers/char/hw_random/intel-rng.c	2006-05-08 00:11:35.000000000 +0200
> @@ -0,0 +1,198 @@
> +/*
> + * RNG driver for Intel 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@xxxxxxxxxx>
> + *
> + * derived from
> + *
> + * Hardware driver for the AMD 768 Random Number Generator (RNG)
> + * (c) Copyright 2001 Red Hat Inc <alan@xxxxxxxxxx>
> + *
> + * derived from
> + *
> + * Hardware driver for Intel i810 Random Number Generator (RNG)
> + * Copyright 2000,2001 Jeff Garzik <jgarzik@xxxxxxxxx>
> + * Copyright 2000,2001 Philipp Rumpf <prumpf@xxxxxxxxxxxxxxxx>
> + *
> + * 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/module.h>
> +#include <linux/kernel.h>
> +#include <linux/pci.h>
> +#include <linux/hw_random.h>
> +#include <asm/io.h>
> +
> +
> +#define PFX	KBUILD_MODNAME ": "
> +
> +/*
> + * RNG registers
> + */
> +#define INTEL_RNG_HW_STATUS			0
> +#define         INTEL_RNG_PRESENT		0x40
> +#define         INTEL_RNG_ENABLED		0x01
> +#define INTEL_RNG_STATUS			1
> +#define         INTEL_RNG_DATA_PRESENT		0x01
> +#define INTEL_RNG_DATA				2
> +
> +/*
> + * Magic address at which Intel PCI bridges locate the RNG
> + */
> +#define INTEL_RNG_ADDR				0xFFBC015F
> +#define INTEL_RNG_ADDR_LEN			3
> +
> +/*
> + * 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 struct pci_device_id pci_tbl[] = {

Should be const.

> +	{ 0x8086, 0x2418, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
> +	{ 0x8086, 0x2428, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
> +	{ 0x8086, 0x2430, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
> +	{ 0x8086, 0x2448, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
> +	{ 0x8086, 0x244e, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
> +	{ 0x8086, 0x245e, PCI_ANY_ID, PCI_ANY_ID, 0, 0, 0, },
> +	{ 0, },	/* terminate list */
> +};
> +MODULE_DEVICE_TABLE(pci, pci_tbl);
> +
> +
> +static inline u8 hwstatus_get(void __iomem *mem)
> +{
> +	return readb(mem + INTEL_RNG_HW_STATUS);
> +}
> +
> +static inline u8 hwstatus_set(void __iomem *mem,
> +			      u8 hw_status)
> +{
> +	writeb(hw_status, mem + INTEL_RNG_HW_STATUS);
> +	return hwstatus_get(mem);
> +}
> +
> +static int intel_rng_data_present(struct hwrng *rng)
> +{
> +	void __iomem *mem = (void __iomem *)rng->priv;
> +
> +	return !!(readb(mem + INTEL_RNG_STATUS) & INTEL_RNG_DATA_PRESENT);
> +}
> +
> +static int intel_rng_data_read(struct hwrng *rng, u32 *data)
> +{
> +	void __iomem *mem = (void __iomem *)rng->priv;
> +
> +	*data = readb(mem + INTEL_RNG_DATA);
> +
> +	return 1;
> +}
> +
> +static int intel_rng_init(struct hwrng *rng)
> +{
> +	void __iomem *mem = (void __iomem *)rng->priv;
> +	u8 hw_status;
> +	int err = -EIO;
> +
> +	hw_status = hwstatus_get(mem);
> +	/* turn RNG h/w on, if it's off */
> +	if ((hw_status & INTEL_RNG_ENABLED) == 0)
> +		hw_status = hwstatus_set(mem, hw_status | INTEL_RNG_ENABLED);
> +	if ((hw_status & INTEL_RNG_ENABLED) == 0) {
> +		printk(KERN_ERR PFX "cannot enable RNG, aborting\n");
> +		goto out;
> +	}
> +	err = 0;
> +out:
> +	return err;
> +}
> +
> +static void intel_rng_cleanup(struct hwrng *rng)
> +{
> +	void __iomem *mem = (void __iomem *)rng->priv;
> +	u8 hw_status;
> +
> +	hw_status = hwstatus_get(mem);
> +	if (hw_status & INTEL_RNG_ENABLED)
> +		hwstatus_set(mem, hw_status & ~INTEL_RNG_ENABLED);
> +	else
> +		printk(KERN_WARNING PFX "unusual: RNG already disabled\n");
> +}
> +
> +
> +static struct hwrng intel_rng = {
> +	.name		= "intel",
> +	.init		= intel_rng_init,
> +	.cleanup	= intel_rng_cleanup,
> +	.data_present	= intel_rng_data_present,
> +	.data_read	= intel_rng_data_read,
> +};
> +
> +
> +static int __init mod_init(void)
> +{
> +	int err = -ENODEV;
> +	struct pci_dev *pdev = NULL;
> +	const struct pci_device_id *ent;
> +	void __iomem *mem;
> +	u8 hw_status;
> +
> +	for_each_pci_dev(pdev) {
> +		ent = pci_match_id(pci_tbl, pdev);
> +		if (ent)
> +			goto found;
> +	}
> +	/* Device not found. */
> +	goto out;

	if (!pci_dev_present(pci_tbl))
		goto out;

> +
> +found:
> +	err = -ENOMEM;
> +	mem = ioremap(INTEL_RNG_ADDR, INTEL_RNG_ADDR_LEN);
> +	if (!mem)
> +		goto out;
> +	intel_rng.priv = (unsigned long)mem;
> +
> +	/* Check for Intel 82802 */
> +	err = -ENODEV;
> +	hw_status = hwstatus_get(mem);
> +	if ((hw_status & INTEL_RNG_PRESENT) == 0)
> +		goto err_unmap;
> +
> +	printk(KERN_INFO "Intel 82802 RNG detected\n");
> +	err = hwrng_register(&intel_rng);
> +	if (err) {
> +		printk(KERN_ERR PFX "RNG registering failed (%d)\n",
> +		       err);
> +		goto out;

		goto err_unmap;

> +	}
> +out:
> +	return err;
> +
> +err_unmap:
> +	iounmap(mem);
> +	goto out;
> +}
> +
> +static void __exit mod_exit(void)
> +{
> +	void __iomem *mem = (void __iomem *)intel_rng.priv;
> +
> +	hwrng_unregister(&intel_rng);
> +	iounmap(mem);
> +}
> +
> +subsys_initcall(mod_init);
> +module_exit(mod_exit);
> +
> +MODULE_AUTHOR("The Linux Kernel team");
> +MODULE_DESCRIPTION("H/W RNG driver for Intel chipsets");
> +MODULE_LICENSE("GPL");
> 
> --

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