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