// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2006-2007 PA Semi, Inc
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*
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* Maintained by: Olof Johansson <olof@lixom.net>
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*
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* Driver for the PWRficient onchip rng
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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_address.h>
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#include <linux/of_platform.h>
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#include <linux/io.h>
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#define SDCRNG_CTL_REG 0x00
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#define SDCRNG_CTL_FVLD_M 0x0000f000
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#define SDCRNG_CTL_FVLD_S 12
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#define SDCRNG_CTL_KSZ 0x00000800
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#define SDCRNG_CTL_RSRC_CRG 0x00000010
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#define SDCRNG_CTL_RSRC_RRG 0x00000000
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#define SDCRNG_CTL_CE 0x00000004
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#define SDCRNG_CTL_RE 0x00000002
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#define SDCRNG_CTL_DR 0x00000001
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#define SDCRNG_CTL_SELECT_RRG_RNG (SDCRNG_CTL_RE | SDCRNG_CTL_RSRC_RRG)
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#define SDCRNG_CTL_SELECT_CRG_RNG (SDCRNG_CTL_CE | SDCRNG_CTL_RSRC_CRG)
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#define SDCRNG_VAL_REG 0x20
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#define MODULE_NAME "pasemi_rng"
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static int pasemi_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 data, i;
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for (i = 0; i < 20; i++) {
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data = (in_le32(rng_regs + SDCRNG_CTL_REG)
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& SDCRNG_CTL_FVLD_M) ? 1 : 0;
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if (data || !wait)
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break;
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udelay(10);
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}
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return data;
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}
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static int pasemi_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 + SDCRNG_VAL_REG);
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return 4;
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}
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static int pasemi_rng_init(struct hwrng *rng)
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{
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void __iomem *rng_regs = (void __iomem *)rng->priv;
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u32 ctl;
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ctl = SDCRNG_CTL_DR | SDCRNG_CTL_SELECT_RRG_RNG | SDCRNG_CTL_KSZ;
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out_le32(rng_regs + SDCRNG_CTL_REG, ctl);
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out_le32(rng_regs + SDCRNG_CTL_REG, ctl & ~SDCRNG_CTL_DR);
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return 0;
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}
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static void pasemi_rng_cleanup(struct hwrng *rng)
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{
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void __iomem *rng_regs = (void __iomem *)rng->priv;
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u32 ctl;
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ctl = SDCRNG_CTL_RE | SDCRNG_CTL_CE;
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out_le32(rng_regs + SDCRNG_CTL_REG,
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in_le32(rng_regs + SDCRNG_CTL_REG) & ~ctl);
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}
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static struct hwrng pasemi_rng = {
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.name = MODULE_NAME,
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.init = pasemi_rng_init,
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.cleanup = pasemi_rng_cleanup,
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.data_present = pasemi_rng_data_present,
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.data_read = pasemi_rng_data_read,
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};
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static int rng_probe(struct platform_device *pdev)
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{
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void __iomem *rng_regs;
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rng_regs = devm_platform_ioremap_resource(pdev, 0);
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if (IS_ERR(rng_regs))
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return PTR_ERR(rng_regs);
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pasemi_rng.priv = (unsigned long)rng_regs;
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pr_info("Registering PA Semi RNG\n");
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return devm_hwrng_register(&pdev->dev, &pasemi_rng);
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}
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static const struct of_device_id rng_match[] = {
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{ .compatible = "1682m-rng", },
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{ .compatible = "pasemi,pwrficient-rng", },
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{ },
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};
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MODULE_DEVICE_TABLE(of, rng_match);
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static struct platform_driver rng_driver = {
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.driver = {
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.name = "pasemi-rng",
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.of_match_table = rng_match,
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},
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.probe = rng_probe,
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};
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module_platform_driver(rng_driver);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Egor Martovetsky <egor@pasemi.com>");
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MODULE_DESCRIPTION("H/W RNG driver for PA Semi processor");
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