text: /*
   * Generic PowerPC 44x RNG driver
   *
   * Copyright 2011 IBM Corporation
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License as published by the
   * Free Software Foundation; version 2 of the License.
   */
  
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/interrupt.h>
  #include <linux/platform_device.h>
  #include <linux/hw_random.h>
  #include <linux/delay.h>
  #include <linux/of_address.h>
  #include <linux/of_platform.h>
  #include <linux/io.h>
  
  #include "crypto4xx_core.h"
  #include "crypto4xx_trng.h"
  #include "crypto4xx_reg_def.h"
  
  #define PPC4XX_TRNG_CTRL	0x0008
  #define PPC4XX_TRNG_CTRL_DALM	0x20
  #define PPC4XX_TRNG_STAT	0x0004
  #define PPC4XX_TRNG_STAT_B	0x1
  #define PPC4XX_TRNG_DATA	0x0000
  
  static int ppc4xx_trng_data_present(struct hwrng *rng, int wait)
  {
  	struct crypto4xx_device *dev = (void *)rng->priv;
  	int busy, i, present = 0;
  
  	for (i = 0; i < 20; i++) {
  		busy = (in_le32(dev->trng_base + PPC4XX_TRNG_STAT) &
  			PPC4XX_TRNG_STAT_B);
  		if (!busy || !wait) {
  			present = 1;
  			break;
  		}
  		udelay(10);
  	}
  	return present;
  }
  
  static int ppc4xx_trng_data_read(struct hwrng *rng, u32 *data)
  {
  	struct crypto4xx_device *dev = (void *)rng->priv;
  	*data = in_le32(dev->trng_base + PPC4XX_TRNG_DATA);
  	return 4;
  }
  
  static void ppc4xx_trng_enable(struct crypto4xx_device *dev, bool enable)
  {
  	u32 device_ctrl;
  
  	device_ctrl = readl(dev->ce_base + CRYPTO4XX_DEVICE_CTRL);
  	if (enable)
  		device_ctrl |= PPC4XX_TRNG_EN;
  	else
  		device_ctrl &= ~PPC4XX_TRNG_EN;
  	writel(device_ctrl, dev->ce_base + CRYPTO4XX_DEVICE_CTRL);
  }
  
  static const struct of_device_id ppc4xx_trng_match[] = {
  	{ .compatible = "ppc4xx-rng", },
  	{ .compatible = "amcc,ppc460ex-rng", },
  	{ .compatible = "amcc,ppc440epx-rng", },
  	{},
  };
  
  void ppc4xx_trng_probe(struct crypto4xx_core_device *core_dev)
  {
  	struct crypto4xx_device *dev = core_dev->dev;
  	struct device_node *trng = NULL;
  	struct hwrng *rng = NULL;
  	int err;
  
  	/* Find the TRNG device node and map it */
  	trng = of_find_matching_node(NULL, ppc4xx_trng_match);
  	if (!trng || !of_device_is_available(trng))
  		return;
  
  	dev->trng_base = of_iomap(trng, 0);
  	of_node_put(trng);
  	if (!dev->trng_base)
  		goto err_out;
  
  	rng = kzalloc(sizeof(*rng), GFP_KERNEL);
  	if (!rng)
  		goto err_out;
  
  	rng->name = KBUILD_MODNAME;
  	rng->data_present = ppc4xx_trng_data_present;
  	rng->data_read = ppc4xx_trng_data_read;
  	rng->priv = (unsigned long) dev;
  	core_dev->trng = rng;
  	ppc4xx_trng_enable(dev, true);
  	out_le32(dev->trng_base + PPC4XX_TRNG_CTRL, PPC4XX_TRNG_CTRL_DALM);
  	err = devm_hwrng_register(core_dev->device, core_dev->trng);
  	if (err) {
  		ppc4xx_trng_enable(dev, false);
  		dev_err(core_dev->device, "failed to register hwrng (%d).\n",
  			err);
  		goto err_out;
  	}
  	return;
  
  err_out:
  	of_node_put(trng);
  	iounmap(dev->trng_base);
  	kfree(rng);
  	dev->trng_base = NULL;
  	core_dev->trng = NULL;
  }
  
  void ppc4xx_trng_remove(struct crypto4xx_core_device *core_dev)
  {
  	if (core_dev && core_dev->trng) {
  		struct crypto4xx_device *dev = core_dev->dev;
  
  		devm_hwrng_unregister(core_dev->device, core_dev->trng);
  		ppc4xx_trng_enable(dev, false);
  		iounmap(dev->trng_base);
  		kfree(core_dev->trng);
  	}
  }
  
  MODULE_ALIAS("ppc4xx_rng");
  