258 lines
6.5 KiB
C
258 lines
6.5 KiB
C
/*
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* Random Number Generator driver for the Keystone SOC
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*
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* Copyright (C) 2016 Texas Instruments Incorporated - http://www.ti.com
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*
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* Authors: Sandeep Nair
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* Vitaly Andrianov
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* version 2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*/
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#include <linux/hw_random.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/io.h>
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#include <linux/platform_device.h>
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#include <linux/clk.h>
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#include <linux/pm_runtime.h>
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#include <linux/err.h>
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#include <linux/regmap.h>
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#include <linux/mfd/syscon.h>
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#include <linux/of.h>
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#include <linux/of_address.h>
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#include <linux/delay.h>
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#define SA_CMD_STATUS_OFS 0x8
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/* TRNG enable control in SA System module*/
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#define SA_CMD_STATUS_REG_TRNG_ENABLE BIT(3)
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/* TRNG start control in TRNG module */
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#define TRNG_CNTL_REG_TRNG_ENABLE BIT(10)
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/* Data ready indicator in STATUS register */
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#define TRNG_STATUS_REG_READY BIT(0)
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/* Data ready clear control in INTACK register */
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#define TRNG_INTACK_REG_READY BIT(0)
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/*
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* Number of samples taken to gather entropy during startup.
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* If value is 0, the number of samples is 2^24 else
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* equals value times 2^8.
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*/
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#define TRNG_DEF_STARTUP_CYCLES 0
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#define TRNG_CNTL_REG_STARTUP_CYCLES_SHIFT 16
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/*
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* Minimum number of samples taken to regenerate entropy
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* If value is 0, the number of samples is 2^24 else
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* equals value times 2^6.
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*/
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#define TRNG_DEF_MIN_REFILL_CYCLES 1
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#define TRNG_CFG_REG_MIN_REFILL_CYCLES_SHIFT 0
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/*
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* Maximum number of samples taken to regenerate entropy
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* If value is 0, the number of samples is 2^24 else
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* equals value times 2^8.
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*/
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#define TRNG_DEF_MAX_REFILL_CYCLES 0
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#define TRNG_CFG_REG_MAX_REFILL_CYCLES_SHIFT 16
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/* Number of CLK input cycles between samples */
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#define TRNG_DEF_CLK_DIV_CYCLES 0
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#define TRNG_CFG_REG_SAMPLE_DIV_SHIFT 8
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/* Maximum retries to get rng data */
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#define SA_MAX_RNG_DATA_RETRIES 5
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/* Delay between retries (in usecs) */
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#define SA_RNG_DATA_RETRY_DELAY 5
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struct trng_regs {
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u32 output_l;
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u32 output_h;
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u32 status;
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u32 intmask;
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u32 intack;
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u32 control;
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u32 config;
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};
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struct ks_sa_rng {
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struct device *dev;
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struct hwrng rng;
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struct clk *clk;
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struct regmap *regmap_cfg;
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struct trng_regs *reg_rng;
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};
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static int ks_sa_rng_init(struct hwrng *rng)
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{
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u32 value;
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struct device *dev = (struct device *)rng->priv;
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struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
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/* Enable RNG module */
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regmap_write_bits(ks_sa_rng->regmap_cfg, SA_CMD_STATUS_OFS,
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SA_CMD_STATUS_REG_TRNG_ENABLE,
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SA_CMD_STATUS_REG_TRNG_ENABLE);
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/* Configure RNG module */
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writel(0, &ks_sa_rng->reg_rng->control);
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value = TRNG_DEF_STARTUP_CYCLES << TRNG_CNTL_REG_STARTUP_CYCLES_SHIFT;
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writel(value, &ks_sa_rng->reg_rng->control);
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value = (TRNG_DEF_MIN_REFILL_CYCLES <<
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TRNG_CFG_REG_MIN_REFILL_CYCLES_SHIFT) |
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(TRNG_DEF_MAX_REFILL_CYCLES <<
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TRNG_CFG_REG_MAX_REFILL_CYCLES_SHIFT) |
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(TRNG_DEF_CLK_DIV_CYCLES <<
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TRNG_CFG_REG_SAMPLE_DIV_SHIFT);
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writel(value, &ks_sa_rng->reg_rng->config);
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/* Disable all interrupts from TRNG */
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writel(0, &ks_sa_rng->reg_rng->intmask);
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/* Enable RNG */
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value = readl(&ks_sa_rng->reg_rng->control);
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value |= TRNG_CNTL_REG_TRNG_ENABLE;
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writel(value, &ks_sa_rng->reg_rng->control);
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return 0;
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}
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static void ks_sa_rng_cleanup(struct hwrng *rng)
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{
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struct device *dev = (struct device *)rng->priv;
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struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
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/* Disable RNG */
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writel(0, &ks_sa_rng->reg_rng->control);
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regmap_write_bits(ks_sa_rng->regmap_cfg, SA_CMD_STATUS_OFS,
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SA_CMD_STATUS_REG_TRNG_ENABLE, 0);
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}
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static int ks_sa_rng_data_read(struct hwrng *rng, u32 *data)
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{
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struct device *dev = (struct device *)rng->priv;
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struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
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/* Read random data */
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data[0] = readl(&ks_sa_rng->reg_rng->output_l);
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data[1] = readl(&ks_sa_rng->reg_rng->output_h);
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writel(TRNG_INTACK_REG_READY, &ks_sa_rng->reg_rng->intack);
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return sizeof(u32) * 2;
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}
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static int ks_sa_rng_data_present(struct hwrng *rng, int wait)
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{
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struct device *dev = (struct device *)rng->priv;
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struct ks_sa_rng *ks_sa_rng = dev_get_drvdata(dev);
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u32 ready;
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int j;
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for (j = 0; j < SA_MAX_RNG_DATA_RETRIES; j++) {
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ready = readl(&ks_sa_rng->reg_rng->status);
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ready &= TRNG_STATUS_REG_READY;
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if (ready || !wait)
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break;
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udelay(SA_RNG_DATA_RETRY_DELAY);
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}
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return ready;
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}
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static int ks_sa_rng_probe(struct platform_device *pdev)
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{
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struct ks_sa_rng *ks_sa_rng;
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struct device *dev = &pdev->dev;
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int ret;
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struct resource *mem;
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ks_sa_rng = devm_kzalloc(dev, sizeof(*ks_sa_rng), GFP_KERNEL);
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if (!ks_sa_rng)
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return -ENOMEM;
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ks_sa_rng->dev = dev;
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ks_sa_rng->rng = (struct hwrng) {
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.name = "ks_sa_hwrng",
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.init = ks_sa_rng_init,
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.data_read = ks_sa_rng_data_read,
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.data_present = ks_sa_rng_data_present,
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.cleanup = ks_sa_rng_cleanup,
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};
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ks_sa_rng->rng.priv = (unsigned long)dev;
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mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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ks_sa_rng->reg_rng = devm_ioremap_resource(dev, mem);
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if (IS_ERR(ks_sa_rng->reg_rng))
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return PTR_ERR(ks_sa_rng->reg_rng);
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ks_sa_rng->regmap_cfg =
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syscon_regmap_lookup_by_phandle(dev->of_node,
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"ti,syscon-sa-cfg");
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if (IS_ERR(ks_sa_rng->regmap_cfg)) {
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dev_err(dev, "syscon_node_to_regmap failed\n");
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return -EINVAL;
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}
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pm_runtime_enable(dev);
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ret = pm_runtime_get_sync(dev);
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if (ret < 0) {
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dev_err(dev, "Failed to enable SA power-domain\n");
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pm_runtime_disable(dev);
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return ret;
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}
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platform_set_drvdata(pdev, ks_sa_rng);
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return devm_hwrng_register(&pdev->dev, &ks_sa_rng->rng);
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}
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static int ks_sa_rng_remove(struct platform_device *pdev)
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{
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pm_runtime_put_sync(&pdev->dev);
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pm_runtime_disable(&pdev->dev);
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return 0;
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}
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static const struct of_device_id ks_sa_rng_dt_match[] = {
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{
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.compatible = "ti,keystone-rng",
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},
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{ },
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};
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MODULE_DEVICE_TABLE(of, ks_sa_rng_dt_match);
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static struct platform_driver ks_sa_rng_driver = {
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.driver = {
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.name = "ks-sa-rng",
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.of_match_table = ks_sa_rng_dt_match,
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},
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.probe = ks_sa_rng_probe,
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.remove = ks_sa_rng_remove,
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};
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module_platform_driver(ks_sa_rng_driver);
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MODULE_DESCRIPTION("Keystone NETCP SA H/W Random Number Generator driver");
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MODULE_AUTHOR("Vitaly Andrianov <vitalya@ti.com>");
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MODULE_LICENSE("GPL");
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