hwrng: st - Add support for ST's HW Random Number Generator (4a4da53c) · Commits · e / devices / android_kernel_fairphone_FP4

drivers/char/hw_random/Kconfig

+10 −0

Original line number	Original line	Diff line number	Diff line
	@@ -346,6 +346,16 @@ config HW_RANDOM_MSM

	If unsure, say Y.		If unsure, say Y.

			config HW_RANDOM_ST
			tristate "ST Microelectronics HW Random Number Generator support"
			depends on HW_RANDOM && ARCH_STI
			---help---
			This driver provides kernel-side support for the Random Number
			Generator hardware found on STi series of SoCs.

			To compile this driver as a module, choose M here: the
			module will be called st-rng.

	config HW_RANDOM_XGENE		config HW_RANDOM_XGENE
	tristate "APM X-Gene True Random Number Generator (TRNG) support"		tristate "APM X-Gene True Random Number Generator (TRNG) support"
	depends on HW_RANDOM && ARCH_XGENE		depends on HW_RANDOM && ARCH_XGENE

drivers/char/hw_random/Makefile

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -30,4 +30,5 @@ obj-$(CONFIG_HW_RANDOM_TPM) += tpm-rng.o
	obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o		obj-$(CONFIG_HW_RANDOM_BCM2835) += bcm2835-rng.o
	obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o		obj-$(CONFIG_HW_RANDOM_IPROC_RNG200) += iproc-rng200.o
	obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o		obj-$(CONFIG_HW_RANDOM_MSM) += msm-rng.o
			obj-$(CONFIG_HW_RANDOM_ST) += st-rng.o
	obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o		obj-$(CONFIG_HW_RANDOM_XGENE) += xgene-rng.o

drivers/char/hw_random/st-rng.c

0 → 100644

+144 −0

Original line number	Original line	Diff line number	Diff line
			/*
			* ST Random Number Generator Driver ST's Platforms
			*
			* Author: Pankaj Dev: <pankaj.dev@st.com>
			* Lee Jones <lee.jones@linaro.org>
			*
			* Copyright (C) 2015 STMicroelectronics (R&D) Limited
			*
			* 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.
			*/

			#include <linux/clk.h>
			#include <linux/delay.h>
			#include <linux/hw_random.h>
			#include <linux/io.h>
			#include <linux/module.h>
			#include <linux/of.h>
			#include <linux/platform_device.h>
			#include <linux/slab.h>

			/* Registers */
			#define ST_RNG_STATUS_REG 0x20
			#define ST_RNG_DATA_REG 0x24

			/* Registers fields */
			#define ST_RNG_STATUS_BAD_SEQUENCE BIT(0)
			#define ST_RNG_STATUS_BAD_ALTERNANCE BIT(1)
			#define ST_RNG_STATUS_FIFO_FULL BIT(5)

			#define ST_RNG_FIFO_SIZE 8
			#define ST_RNG_SAMPLE_SIZE 2 /* 2 Byte (16bit) samples */

			/* Samples are available every 0.667us, which we round to 1us */
			#define ST_RNG_FILL_FIFO_TIMEOUT (1 * (ST_RNG_FIFO_SIZE / ST_RNG_SAMPLE_SIZE))

			struct st_rng_data {
			void __iomem *base;
			struct clk *clk;
			struct hwrng ops;
			};

			static int st_rng_read(struct hwrng rng, void data, size_t max, bool wait)
			{
			struct st_rng_data ddata = (struct st_rng_data )rng->priv;
			u32 status;
			int i;

			if (max < sizeof(u16))
			return -EINVAL;

			/* Wait until FIFO is full - max 4uS*/
			for (i = 0; i < ST_RNG_FILL_FIFO_TIMEOUT; i++) {
			status = readl_relaxed(ddata->base + ST_RNG_STATUS_REG);
			if (status & ST_RNG_STATUS_FIFO_FULL)
			break;
			udelay(1);
			}

			if (i == ST_RNG_FILL_FIFO_TIMEOUT)
			return 0;

			for (i = 0; i < ST_RNG_FIFO_SIZE && i < max; i += 2)
			(u16 )(data + i) =
			readl_relaxed(ddata->base + ST_RNG_DATA_REG);

			return i; /* No of bytes read */
			}

			static int st_rng_probe(struct platform_device *pdev)
			{
			struct st_rng_data *ddata;
			struct resource *res;
			struct clk *clk;
			void __iomem *base;
			int ret;

			ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
			if (!ddata)
			return -ENOMEM;

			res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
			base = devm_ioremap_resource(&pdev->dev, res);
			if (IS_ERR(base))
			return PTR_ERR(base);

			clk = devm_clk_get(&pdev->dev, NULL);
			if (IS_ERR(clk))
			return PTR_ERR(clk);

			ret = clk_prepare_enable(clk);
			if (ret)
			return ret;

			ddata->ops.priv = (unsigned long)ddata;
			ddata->ops.read = st_rng_read;
			ddata->ops.name = pdev->name;
			ddata->base = base;
			ddata->clk = clk;

			dev_set_drvdata(&pdev->dev, ddata);

			ret = hwrng_register(&ddata->ops);
			if (ret) {
			dev_err(&pdev->dev, "Failed to register HW RNG\n");
			return ret;
			}

			dev_info(&pdev->dev, "Successfully registered HW RNG\n");

			return 0;
			}

			static int st_rng_remove(struct platform_device *pdev)
			{
			struct st_rng_data *ddata = dev_get_drvdata(&pdev->dev);

			hwrng_unregister(&ddata->ops);

			clk_disable_unprepare(ddata->clk);

			return 0;
			}

			static const struct of_device_id st_rng_match[] = {
			{ .compatible = "st,rng" },
			{},
			};
			MODULE_DEVICE_TABLE(of, st_rng_match);

			static struct platform_driver st_rng_driver = {
			.driver = {
			.name = "st-hwrandom",
			.of_match_table = of_match_ptr(st_rng_match),
			},
			.probe = st_rng_probe,
			.remove = st_rng_remove
			};

			module_platform_driver(st_rng_driver);

			MODULE_AUTHOR("Pankaj Dev <pankaj.dev@st.com>");
			MODULE_LICENSE("GPL v2");