drivers/char/hw_random/imx-rngc.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
  * RNG driver for Freescale RNGC
  *
  * Copyright (C) 2008-2012 Freescale Semiconductor, Inc.
  * Copyright (C) 2017 Martin Kaiser <martin@kaiser.cx>
  */

 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/platform_device.h>
 #include <linux/interrupt.h>
 #include <linux/hw_random.h>
 #include <linux/completion.h>
 #include <linux/io.h>

 #define RNGC_VER_ID			0x0000
 #define RNGC_COMMAND			0x0004
 #define RNGC_CONTROL			0x0008
 #define RNGC_STATUS			0x000C
 #define RNGC_ERROR			0x0010
 #define RNGC_FIFO			0x0014

 /* the fields in the ver id register */
 #define RNGC_TYPE_SHIFT		28
 #define RNGC_VER_MAJ_SHIFT		8

 /* the rng_type field */
 #define RNGC_TYPE_RNGB			0x1
 #define RNGC_TYPE_RNGC			0x2


 #define RNGC_CMD_CLR_ERR		0x00000020
 #define RNGC_CMD_CLR_INT		0x00000010
 #define RNGC_CMD_SEED			0x00000002
 #define RNGC_CMD_SELF_TEST		0x00000001

 #define RNGC_CTRL_MASK_ERROR		0x00000040
 #define RNGC_CTRL_MASK_DONE		0x00000020
 #define RNGC_CTRL_AUTO_SEED		0x00000010

 #define RNGC_STATUS_ERROR		0x00010000
 #define RNGC_STATUS_FIFO_LEVEL_MASK	0x00000f00
 #define RNGC_STATUS_FIFO_LEVEL_SHIFT	8
 #define RNGC_STATUS_SEED_DONE		0x00000020
 #define RNGC_STATUS_ST_DONE		0x00000010

 #define RNGC_ERROR_STATUS_STAT_ERR	0x00000008

 #define RNGC_TIMEOUT  3000 /* 3 sec */


 static bool self_test = true;
 module_param(self_test, bool, 0);

 struct imx_rngc {
 	struct device		*dev;
 	struct clk		*clk;
 	void __iomem		*base;
 	struct hwrng		rng;
 	struct completion	rng_op_done;
 	/*
 	 * err_reg is written only by the irq handler and read only
 	 * when interrupts are masked, we need no spinlock
 	 */
 	u32			err_reg;
 };


 static inline void imx_rngc_irq_mask_clear(struct imx_rngc *rngc)
 {
 	u32 ctrl, cmd;

 	/* mask interrupts */
 	ctrl = readl(rngc->base + RNGC_CONTROL);
 	ctrl |= RNGC_CTRL_MASK_DONE | RNGC_CTRL_MASK_ERROR;
 	writel(ctrl, rngc->base + RNGC_CONTROL);

 	/*
 	 * CLR_INT clears the interrupt only if there's no error
 	 * CLR_ERR clear the interrupt and the error register if there
 	 * is an error
 	 */
 	cmd = readl(rngc->base + RNGC_COMMAND);
 	cmd |= RNGC_CMD_CLR_INT | RNGC_CMD_CLR_ERR;
 	writel(cmd, rngc->base + RNGC_COMMAND);
 }

 static inline void imx_rngc_irq_unmask(struct imx_rngc *rngc)
 {
 	u32 ctrl;

 	ctrl = readl(rngc->base + RNGC_CONTROL);
 	ctrl &= ~(RNGC_CTRL_MASK_DONE | RNGC_CTRL_MASK_ERROR);
 	writel(ctrl, rngc->base + RNGC_CONTROL);
 }

 static int imx_rngc_self_test(struct imx_rngc *rngc)
 {
 	u32 cmd;
 	int ret;

 	imx_rngc_irq_unmask(rngc);

 	/* run self test */
 	cmd = readl(rngc->base + RNGC_COMMAND);
 	writel(cmd | RNGC_CMD_SELF_TEST, rngc->base + RNGC_COMMAND);

 	ret = wait_for_completion_timeout(&rngc->rng_op_done, RNGC_TIMEOUT);
 	imx_rngc_irq_mask_clear(rngc);
 	if (!ret)
 		return -ETIMEDOUT;

 	return rngc->err_reg ? -EIO : 0;
 }

 static int imx_rngc_read(struct hwrng *rng, void *data, size_t max, bool wait)
 {
 	struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng);
 	unsigned int status;
 	unsigned int level;
 	int retval = 0;

 	while (max >= sizeof(u32)) {
 		status = readl(rngc->base + RNGC_STATUS);

 		/* is there some error while reading this random number? */
 		if (status & RNGC_STATUS_ERROR)
 			break;

 		/* how many random numbers are in FIFO? [0-16] */
 		level = (status & RNGC_STATUS_FIFO_LEVEL_MASK) >>
 			RNGC_STATUS_FIFO_LEVEL_SHIFT;

 		if (level) {
 			/* retrieve a random number from FIFO */
 			*(u32 *)data = readl(rngc->base + RNGC_FIFO);

 			retval += sizeof(u32);
 			data += sizeof(u32);
 			max -= sizeof(u32);
 		}
 	}

 	return retval ? retval : -EIO;
 }

 static irqreturn_t imx_rngc_irq(int irq, void *priv)
 {
 	struct imx_rngc *rngc = (struct imx_rngc *)priv;
 	u32 status;

 	/*
 	 * clearing the interrupt will also clear the error register
 	 * read error and status before clearing
 	 */
 	status = readl(rngc->base + RNGC_STATUS);
 	rngc->err_reg = readl(rngc->base + RNGC_ERROR);

 	imx_rngc_irq_mask_clear(rngc);

 	if (status & (RNGC_STATUS_SEED_DONE | RNGC_STATUS_ST_DONE))
 		complete(&rngc->rng_op_done);

 	return IRQ_HANDLED;
 }

 static int imx_rngc_init(struct hwrng *rng)
 {
 	struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng);
 	u32 cmd, ctrl;
 	int ret;

 	/* clear error */
 	cmd = readl(rngc->base + RNGC_COMMAND);
 	writel(cmd | RNGC_CMD_CLR_ERR, rngc->base + RNGC_COMMAND);

 	imx_rngc_irq_unmask(rngc);

 	/* create seed, repeat while there is some statistical error */
 	do {
 		/* seed creation */
 		cmd = readl(rngc->base + RNGC_COMMAND);
 		writel(cmd | RNGC_CMD_SEED, rngc->base + RNGC_COMMAND);

 		ret = wait_for_completion_timeout(&rngc->rng_op_done,
 				RNGC_TIMEOUT);

 		if (!ret) {
 			ret = -ETIMEDOUT;
 			goto err;
 		}

 	} while (rngc->err_reg == RNGC_ERROR_STATUS_STAT_ERR);

 	if (rngc->err_reg) {
 		ret = -EIO;
 		goto err;
 	}

 	/*
 	 * enable automatic seeding, the rngc creates a new seed automatically
 	 * after serving 2^20 random 160-bit words
 	 */
 	ctrl = readl(rngc->base + RNGC_CONTROL);
 	ctrl |= RNGC_CTRL_AUTO_SEED;
 	writel(ctrl, rngc->base + RNGC_CONTROL);

 	/*
 	 * if initialisation was successful, we keep the interrupt
 	 * unmasked until imx_rngc_cleanup is called
 	 * we mask the interrupt ourselves if we return an error
 	 */
 	return 0;

 err:
 	imx_rngc_irq_mask_clear(rngc);
 	return ret;
 }

 static void imx_rngc_cleanup(struct hwrng *rng)
 {
 	struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng);

 	imx_rngc_irq_mask_clear(rngc);
 }

 static int imx_rngc_probe(struct platform_device *pdev)
 {
 	struct imx_rngc *rngc;
 	int ret;
 	int irq;
 	u32 ver_id;
 	u8  rng_type;

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

 	rngc->base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(rngc->base))
 		return PTR_ERR(rngc->base);

 	rngc->clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(rngc->clk)) {
 		dev_err(&pdev->dev, "Can not get rng_clk\n");
 		return PTR_ERR(rngc->clk);
 	}

 	irq = platform_get_irq(pdev, 0);
 	if (irq <= 0) {
 		dev_err(&pdev->dev, "Couldn't get irq %d\n", irq);
 		return irq;
 	}

 	ret = clk_prepare_enable(rngc->clk);
 	if (ret)
 		return ret;

 	ver_id = readl(rngc->base + RNGC_VER_ID);
 	rng_type = ver_id >> RNGC_TYPE_SHIFT;
 	/*
 	 * This driver supports only RNGC and RNGB. (There's a different
 	 * driver for RNGA.)
 	 */
 	if (rng_type != RNGC_TYPE_RNGC && rng_type != RNGC_TYPE_RNGB) {
 		ret = -ENODEV;
 		goto err;
 	}

 	ret = devm_request_irq(&pdev->dev,
 			irq, imx_rngc_irq, 0, pdev->name, (void *)rngc);
 	if (ret) {
 		dev_err(rngc->dev, "Can't get interrupt working.\n");
 		goto err;
 	}

 	init_completion(&rngc->rng_op_done);

 	rngc->rng.name = pdev->name;
 	rngc->rng.init = imx_rngc_init;
 	rngc->rng.read = imx_rngc_read;
 	rngc->rng.cleanup = imx_rngc_cleanup;

 	rngc->dev = &pdev->dev;
 	platform_set_drvdata(pdev, rngc);

 	imx_rngc_irq_mask_clear(rngc);

 	if (self_test) {
 		ret = imx_rngc_self_test(rngc);
 		if (ret) {
 			dev_err(rngc->dev, "self test failed\n");
 			goto err;
 		}
 	}

 	ret = hwrng_register(&rngc->rng);
 	if (ret) {
 		dev_err(&pdev->dev, "hwrng registration failed\n");
 		goto err;
 	}

 	dev_info(&pdev->dev,
 		"Freescale RNG%c registered (HW revision %d.%02d)\n",
 		rng_type == RNGC_TYPE_RNGB ? 'B' : 'C',
 		(ver_id >> RNGC_VER_MAJ_SHIFT) & 0xff, ver_id & 0xff);
 	return 0;

 err:
 	clk_disable_unprepare(rngc->clk);

 	return ret;
 }

 static int __exit imx_rngc_remove(struct platform_device *pdev)
 {
 	struct imx_rngc *rngc = platform_get_drvdata(pdev);

 	hwrng_unregister(&rngc->rng);

 	clk_disable_unprepare(rngc->clk);

 	return 0;
 }

 static int __maybe_unused imx_rngc_suspend(struct device *dev)
 {
 	struct imx_rngc *rngc = dev_get_drvdata(dev);

 	clk_disable_unprepare(rngc->clk);

 	return 0;
 }

 static int __maybe_unused imx_rngc_resume(struct device *dev)
 {
 	struct imx_rngc *rngc = dev_get_drvdata(dev);

 	clk_prepare_enable(rngc->clk);

 	return 0;
 }

 static SIMPLE_DEV_PM_OPS(imx_rngc_pm_ops, imx_rngc_suspend, imx_rngc_resume);

 static const struct of_device_id imx_rngc_dt_ids[] = {
 	{ .compatible = "fsl,imx25-rngb", .data = NULL, },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, imx_rngc_dt_ids);

 static struct platform_driver imx_rngc_driver = {
 	.driver = {
 		.name = "imx_rngc",
 		.pm = &imx_rngc_pm_ops,
 		.of_match_table = imx_rngc_dt_ids,
 	},
 	.remove = __exit_p(imx_rngc_remove),
 };

 module_platform_driver_probe(imx_rngc_driver, imx_rngc_probe);

 MODULE_AUTHOR("Freescale Semiconductor, Inc.");
 MODULE_DESCRIPTION("H/W RNGC driver for i.MX");
 MODULE_LICENSE("GPL");
	// SPDX-License-Identifier: GPL-2.0-or-later
	/*
	* RNG driver for Freescale RNGC
	*
	* Copyright (C) 2008-2012 Freescale Semiconductor, Inc.
	* Copyright (C) 2017 Martin Kaiser <martin@kaiser.cx>
	*/

	#include <linux/module.h>
	#include <linux/mod_devicetable.h>
	#include <linux/init.h>
	#include <linux/kernel.h>
	#include <linux/clk.h>
	#include <linux/err.h>
	#include <linux/platform_device.h>
	#include <linux/interrupt.h>
	#include <linux/hw_random.h>
	#include <linux/completion.h>
	#include <linux/io.h>

	#define RNGC_VER_ID 0x0000
	#define RNGC_COMMAND 0x0004
	#define RNGC_CONTROL 0x0008
	#define RNGC_STATUS 0x000C
	#define RNGC_ERROR 0x0010
	#define RNGC_FIFO 0x0014

	/* the fields in the ver id register */
	#define RNGC_TYPE_SHIFT 28
	#define RNGC_VER_MAJ_SHIFT 8

	/* the rng_type field */
	#define RNGC_TYPE_RNGB 0x1
	#define RNGC_TYPE_RNGC 0x2


	#define RNGC_CMD_CLR_ERR 0x00000020
	#define RNGC_CMD_CLR_INT 0x00000010
	#define RNGC_CMD_SEED 0x00000002
	#define RNGC_CMD_SELF_TEST 0x00000001

	#define RNGC_CTRL_MASK_ERROR 0x00000040
	#define RNGC_CTRL_MASK_DONE 0x00000020
	#define RNGC_CTRL_AUTO_SEED 0x00000010

	#define RNGC_STATUS_ERROR 0x00010000
	#define RNGC_STATUS_FIFO_LEVEL_MASK 0x00000f00
	#define RNGC_STATUS_FIFO_LEVEL_SHIFT 8
	#define RNGC_STATUS_SEED_DONE 0x00000020
	#define RNGC_STATUS_ST_DONE 0x00000010

	#define RNGC_ERROR_STATUS_STAT_ERR 0x00000008

	#define RNGC_TIMEOUT 3000 /* 3 sec */


	static bool self_test = true;
	module_param(self_test, bool, 0);

	struct imx_rngc {
	struct device *dev;
	struct clk *clk;
	void __iomem *base;
	struct hwrng rng;
	struct completion rng_op_done;
	/*
	* err_reg is written only by the irq handler and read only
	* when interrupts are masked, we need no spinlock
	*/
	u32 err_reg;
	};


	static inline void imx_rngc_irq_mask_clear(struct imx_rngc *rngc)
	{
	u32 ctrl, cmd;

	/* mask interrupts */
	ctrl = readl(rngc->base + RNGC_CONTROL);
	ctrl \|= RNGC_CTRL_MASK_DONE \| RNGC_CTRL_MASK_ERROR;
	writel(ctrl, rngc->base + RNGC_CONTROL);

	/*
	* CLR_INT clears the interrupt only if there's no error
	* CLR_ERR clear the interrupt and the error register if there
	* is an error
	*/
	cmd = readl(rngc->base + RNGC_COMMAND);
	cmd \|= RNGC_CMD_CLR_INT \| RNGC_CMD_CLR_ERR;
	writel(cmd, rngc->base + RNGC_COMMAND);
	}

	static inline void imx_rngc_irq_unmask(struct imx_rngc *rngc)
	{
	u32 ctrl;

	ctrl = readl(rngc->base + RNGC_CONTROL);
	ctrl &= ~(RNGC_CTRL_MASK_DONE \| RNGC_CTRL_MASK_ERROR);
	writel(ctrl, rngc->base + RNGC_CONTROL);
	}

	static int imx_rngc_self_test(struct imx_rngc *rngc)
	{
	u32 cmd;
	int ret;

	imx_rngc_irq_unmask(rngc);

	/* run self test */
	cmd = readl(rngc->base + RNGC_COMMAND);
	writel(cmd \| RNGC_CMD_SELF_TEST, rngc->base + RNGC_COMMAND);

	ret = wait_for_completion_timeout(&rngc->rng_op_done, RNGC_TIMEOUT);
	imx_rngc_irq_mask_clear(rngc);
	if (!ret)
	return -ETIMEDOUT;

	return rngc->err_reg ? -EIO : 0;
	}

	static int imx_rngc_read(struct hwrng rng, void data, size_t max, bool wait)
	{
	struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng);
	unsigned int status;
	unsigned int level;
	int retval = 0;

	while (max >= sizeof(u32)) {
	status = readl(rngc->base + RNGC_STATUS);

	/* is there some error while reading this random number? */
	if (status & RNGC_STATUS_ERROR)
	break;

	/* how many random numbers are in FIFO? [0-16] */
	level = (status & RNGC_STATUS_FIFO_LEVEL_MASK) >>
	RNGC_STATUS_FIFO_LEVEL_SHIFT;

	if (level) {
	/* retrieve a random number from FIFO */
	(u32 )data = readl(rngc->base + RNGC_FIFO);

	retval += sizeof(u32);
	data += sizeof(u32);
	max -= sizeof(u32);
	}
	}

	return retval ? retval : -EIO;
	}

	static irqreturn_t imx_rngc_irq(int irq, void *priv)
	{
	struct imx_rngc rngc = (struct imx_rngc )priv;
	u32 status;

	/*
	* clearing the interrupt will also clear the error register
	* read error and status before clearing
	*/
	status = readl(rngc->base + RNGC_STATUS);
	rngc->err_reg = readl(rngc->base + RNGC_ERROR);

	imx_rngc_irq_mask_clear(rngc);

	if (status & (RNGC_STATUS_SEED_DONE \| RNGC_STATUS_ST_DONE))
	complete(&rngc->rng_op_done);

	return IRQ_HANDLED;
	}

	static int imx_rngc_init(struct hwrng *rng)
	{
	struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng);
	u32 cmd, ctrl;
	int ret;

	/* clear error */
	cmd = readl(rngc->base + RNGC_COMMAND);
	writel(cmd \| RNGC_CMD_CLR_ERR, rngc->base + RNGC_COMMAND);

	imx_rngc_irq_unmask(rngc);

	/* create seed, repeat while there is some statistical error */
	do {
	/* seed creation */
	cmd = readl(rngc->base + RNGC_COMMAND);
	writel(cmd \| RNGC_CMD_SEED, rngc->base + RNGC_COMMAND);

	ret = wait_for_completion_timeout(&rngc->rng_op_done,
	RNGC_TIMEOUT);

	if (!ret) {
	ret = -ETIMEDOUT;
	goto err;
	}

	} while (rngc->err_reg == RNGC_ERROR_STATUS_STAT_ERR);

	if (rngc->err_reg) {
	ret = -EIO;
	goto err;
	}

	/*
	* enable automatic seeding, the rngc creates a new seed automatically
	* after serving 2^20 random 160-bit words
	*/
	ctrl = readl(rngc->base + RNGC_CONTROL);
	ctrl \|= RNGC_CTRL_AUTO_SEED;
	writel(ctrl, rngc->base + RNGC_CONTROL);

	/*
	* if initialisation was successful, we keep the interrupt
	* unmasked until imx_rngc_cleanup is called
	* we mask the interrupt ourselves if we return an error
	*/
	return 0;

	err:
	imx_rngc_irq_mask_clear(rngc);
	return ret;
	}

	static void imx_rngc_cleanup(struct hwrng *rng)
	{
	struct imx_rngc *rngc = container_of(rng, struct imx_rngc, rng);

	imx_rngc_irq_mask_clear(rngc);
	}

	static int imx_rngc_probe(struct platform_device *pdev)
	{
	struct imx_rngc *rngc;
	int ret;
	int irq;
	u32 ver_id;
	u8 rng_type;

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

	rngc->base = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(rngc->base))
	return PTR_ERR(rngc->base);

	rngc->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(rngc->clk)) {
	dev_err(&pdev->dev, "Can not get rng_clk\n");
	return PTR_ERR(rngc->clk);
	}

	irq = platform_get_irq(pdev, 0);
	if (irq <= 0) {
	dev_err(&pdev->dev, "Couldn't get irq %d\n", irq);
	return irq;
	}

	ret = clk_prepare_enable(rngc->clk);
	if (ret)
	return ret;

	ver_id = readl(rngc->base + RNGC_VER_ID);
	rng_type = ver_id >> RNGC_TYPE_SHIFT;
	/*
	* This driver supports only RNGC and RNGB. (There's a different
	* driver for RNGA.)
	*/
	if (rng_type != RNGC_TYPE_RNGC && rng_type != RNGC_TYPE_RNGB) {
	ret = -ENODEV;
	goto err;
	}

	ret = devm_request_irq(&pdev->dev,
	irq, imx_rngc_irq, 0, pdev->name, (void *)rngc);
	if (ret) {
	dev_err(rngc->dev, "Can't get interrupt working.\n");
	goto err;
	}

	init_completion(&rngc->rng_op_done);

	rngc->rng.name = pdev->name;
	rngc->rng.init = imx_rngc_init;
	rngc->rng.read = imx_rngc_read;
	rngc->rng.cleanup = imx_rngc_cleanup;

	rngc->dev = &pdev->dev;
	platform_set_drvdata(pdev, rngc);

	imx_rngc_irq_mask_clear(rngc);

	if (self_test) {
	ret = imx_rngc_self_test(rngc);
	if (ret) {
	dev_err(rngc->dev, "self test failed\n");
	goto err;
	}
	}

	ret = hwrng_register(&rngc->rng);
	if (ret) {
	dev_err(&pdev->dev, "hwrng registration failed\n");
	goto err;
	}

	dev_info(&pdev->dev,
	"Freescale RNG%c registered (HW revision %d.%02d)\n",
	rng_type == RNGC_TYPE_RNGB ? 'B' : 'C',
	(ver_id >> RNGC_VER_MAJ_SHIFT) & 0xff, ver_id & 0xff);
	return 0;

	err:
	clk_disable_unprepare(rngc->clk);

	return ret;
	}

	static int __exit imx_rngc_remove(struct platform_device *pdev)
	{
	struct imx_rngc *rngc = platform_get_drvdata(pdev);

	hwrng_unregister(&rngc->rng);

	clk_disable_unprepare(rngc->clk);

	return 0;
	}

	static int __maybe_unused imx_rngc_suspend(struct device *dev)
	{
	struct imx_rngc *rngc = dev_get_drvdata(dev);

	clk_disable_unprepare(rngc->clk);

	return 0;
	}

	static int __maybe_unused imx_rngc_resume(struct device *dev)
	{
	struct imx_rngc *rngc = dev_get_drvdata(dev);

	clk_prepare_enable(rngc->clk);

	return 0;
	}

	static SIMPLE_DEV_PM_OPS(imx_rngc_pm_ops, imx_rngc_suspend, imx_rngc_resume);

	static const struct of_device_id imx_rngc_dt_ids[] = {
	{ .compatible = "fsl,imx25-rngb", .data = NULL, },
	{ /* sentinel */ }
	};
	MODULE_DEVICE_TABLE(of, imx_rngc_dt_ids);

	static struct platform_driver imx_rngc_driver = {
	.driver = {
	.name = "imx_rngc",
	.pm = &imx_rngc_pm_ops,
	.of_match_table = imx_rngc_dt_ids,
	},
	.remove = __exit_p(imx_rngc_remove),
	};

	module_platform_driver_probe(imx_rngc_driver, imx_rngc_probe);

	MODULE_AUTHOR("Freescale Semiconductor, Inc.");
	MODULE_DESCRIPTION("H/W RNGC driver for i.MX");
	MODULE_LICENSE("GPL");