157 lines
3.3 KiB
C
157 lines
3.3 KiB
C
/*
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* Generic PowerPC 44x RNG driver
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*
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* Copyright 2011 IBM Corporation
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; version 2 of the License.
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/platform_device.h>
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#include <linux/hw_random.h>
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#include <linux/delay.h>
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#include <linux/of_platform.h>
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#include <asm/io.h>
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#define PPC4XX_TRNG_DEV_CTRL 0x60080
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#define PPC4XX_TRNGE 0x00020000
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#define PPC4XX_TRNG_CTRL 0x0008
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#define PPC4XX_TRNG_CTRL_DALM 0x20
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#define PPC4XX_TRNG_STAT 0x0004
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#define PPC4XX_TRNG_STAT_B 0x1
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#define PPC4XX_TRNG_DATA 0x0000
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#define MODULE_NAME "ppc4xx_rng"
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static int ppc4xx_rng_data_present(struct hwrng *rng, int wait)
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{
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void __iomem *rng_regs = (void __iomem *) rng->priv;
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int busy, i, present = 0;
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for (i = 0; i < 20; i++) {
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busy = (in_le32(rng_regs + PPC4XX_TRNG_STAT) & PPC4XX_TRNG_STAT_B);
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if (!busy || !wait) {
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present = 1;
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break;
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}
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udelay(10);
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}
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return present;
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}
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static int ppc4xx_rng_data_read(struct hwrng *rng, u32 *data)
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{
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void __iomem *rng_regs = (void __iomem *) rng->priv;
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*data = in_le32(rng_regs + PPC4XX_TRNG_DATA);
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return 4;
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}
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static int ppc4xx_rng_enable(int enable)
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{
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struct device_node *ctrl;
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void __iomem *ctrl_reg;
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int err = 0;
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u32 val;
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/* Find the main crypto device node and map it to turn the TRNG on */
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ctrl = of_find_compatible_node(NULL, NULL, "amcc,ppc4xx-crypto");
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if (!ctrl)
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return -ENODEV;
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ctrl_reg = of_iomap(ctrl, 0);
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if (!ctrl_reg) {
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err = -ENODEV;
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goto out;
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}
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val = in_le32(ctrl_reg + PPC4XX_TRNG_DEV_CTRL);
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if (enable)
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val |= PPC4XX_TRNGE;
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else
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val = val & ~PPC4XX_TRNGE;
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out_le32(ctrl_reg + PPC4XX_TRNG_DEV_CTRL, val);
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iounmap(ctrl_reg);
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out:
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of_node_put(ctrl);
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return err;
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}
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static struct hwrng ppc4xx_rng = {
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.name = MODULE_NAME,
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.data_present = ppc4xx_rng_data_present,
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.data_read = ppc4xx_rng_data_read,
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};
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static int __devinit ppc4xx_rng_probe(struct platform_device *dev)
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{
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void __iomem *rng_regs;
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int err = 0;
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rng_regs = of_iomap(dev->dev.of_node, 0);
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if (!rng_regs)
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return -ENODEV;
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err = ppc4xx_rng_enable(1);
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if (err)
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return err;
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out_le32(rng_regs + PPC4XX_TRNG_CTRL, PPC4XX_TRNG_CTRL_DALM);
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ppc4xx_rng.priv = (unsigned long) rng_regs;
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err = hwrng_register(&ppc4xx_rng);
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return err;
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}
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static int __devexit ppc4xx_rng_remove(struct platform_device *dev)
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{
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void __iomem *rng_regs = (void __iomem *) ppc4xx_rng.priv;
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hwrng_unregister(&ppc4xx_rng);
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ppc4xx_rng_enable(0);
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iounmap(rng_regs);
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return 0;
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}
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static struct of_device_id ppc4xx_rng_match[] = {
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{ .compatible = "ppc4xx-rng", },
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{ .compatible = "amcc,ppc460ex-rng", },
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{ .compatible = "amcc,ppc440epx-rng", },
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{},
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};
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static struct platform_driver ppc4xx_rng_driver = {
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.driver = {
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.name = MODULE_NAME,
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.owner = THIS_MODULE,
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.of_match_table = ppc4xx_rng_match,
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},
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.probe = ppc4xx_rng_probe,
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.remove = ppc4xx_rng_remove,
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};
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static int __init ppc4xx_rng_init(void)
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{
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return platform_driver_register(&ppc4xx_rng_driver);
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}
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module_init(ppc4xx_rng_init);
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static void __exit ppc4xx_rng_exit(void)
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{
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platform_driver_unregister(&ppc4xx_rng_driver);
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}
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module_exit(ppc4xx_rng_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Josh Boyer <jwboyer@linux.vnet.ibm.com>");
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MODULE_DESCRIPTION("HW RNG driver for PPC 4xx processors");
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