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path: root/drivers/char/hw_random/intel-rng.c
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Diffstat (limited to 'drivers/char/hw_random/intel-rng.c')
-rw-r--r--drivers/char/hw_random/intel-rng.c189
1 files changed, 189 insertions, 0 deletions
diff --git a/drivers/char/hw_random/intel-rng.c b/drivers/char/hw_random/intel-rng.c
new file mode 100644
index 00000000000..6594bd5645f
--- /dev/null
+++ b/drivers/char/hw_random/intel-rng.c
@@ -0,0 +1,189 @@
+/*
+ * 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@redhat.com>
+ *
+ * derived from
+ *
+ * Hardware driver for the AMD 768 Random Number Generator (RNG)
+ * (c) Copyright 2001 Red Hat Inc <alan@redhat.com>
+ *
+ * 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/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 const struct pci_device_id pci_tbl[] = {
+ { 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;
+ void __iomem *mem;
+ u8 hw_status;
+
+ if (!pci_dev_present(pci_tbl))
+ goto out; /* Device not 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;
+ }
+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_DESCRIPTION("H/W RNG driver for Intel chipsets");
+MODULE_LICENSE("GPL");