text: /*
   * Defines interfaces for interacting wtih the Raspberry Pi firmware's
   * property channel.
   *
   * Copyright © 2015 Broadcom
   *
   * 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/dma-mapping.h>
  #include <linux/mailbox_client.h>
  #include <linux/module.h>
  #include <linux/of_platform.h>
  #include <linux/platform_device.h>
  #include <linux/slab.h>
  #include <soc/bcm2835/raspberrypi-firmware.h>
  
  #define MBOX_MSG(chan, data28)		(((data28) & ~0xf) | ((chan) & 0xf))
  #define MBOX_CHAN(msg)			((msg) & 0xf)
  #define MBOX_DATA28(msg)		((msg) & ~0xf)
  #define MBOX_CHAN_PROPERTY		8
  
  static struct platform_device *rpi_hwmon;
  
  struct rpi_firmware {
  	struct mbox_client cl;
  	struct mbox_chan *chan; /* The property channel. */
  	struct completion c;
  	u32 enabled;
  };
  
  static DEFINE_MUTEX(transaction_lock);
  
  static void response_callback(struct mbox_client *cl, void *msg)
  {
  	struct rpi_firmware *fw = container_of(cl, struct rpi_firmware, cl);
  	complete(&fw->c);
  }
  
  /*
   * Sends a request to the firmware through the BCM2835 mailbox driver,
   * and synchronously waits for the reply.
   */
  static int
  rpi_firmware_transaction(struct rpi_firmware *fw, u32 chan, u32 data)
  {
  	u32 message = MBOX_MSG(chan, data);
  	int ret;
  
  	WARN_ON(data & 0xf);
  
  	mutex_lock(&transaction_lock);
  	reinit_completion(&fw->c);
  	ret = mbox_send_message(fw->chan, &message);
  	if (ret >= 0) {
  		wait_for_completion(&fw->c);
  		ret = 0;
  	} else {
  		dev_err(fw->cl.dev, "mbox_send_message returned %d\n", ret);
  	}
  	mutex_unlock(&transaction_lock);
  
  	return ret;
  }
  
  /**
   * rpi_firmware_property_list - Submit firmware property list
   * @fw:		Pointer to firmware structure from rpi_firmware_get().
   * @data:	Buffer holding tags.
   * @tag_size:	Size of tags buffer.
   *
   * Submits a set of concatenated tags to the VPU firmware through the
   * mailbox property interface.
   *
   * The buffer header and the ending tag are added by this function and
   * don't need to be supplied, just the actual tags for your operation.
   * See struct rpi_firmware_property_tag_header for the per-tag
   * structure.
   */
  int rpi_firmware_property_list(struct rpi_firmware *fw,
  			       void *data, size_t tag_size)
  {
  	size_t size = tag_size + 12;
  	u32 *buf;
  	dma_addr_t bus_addr;
  	int ret;
  
  	/* Packets are processed a dword at a time. */
  	if (size & 3)
  		return -EINVAL;
  
  	buf = dma_alloc_coherent(fw->cl.dev, PAGE_ALIGN(size), &bus_addr,
  				 GFP_ATOMIC);
  	if (!buf)
  		return -ENOMEM;
  
  	/* The firmware will error out without parsing in this case. */
  	WARN_ON(size >= 1024 * 1024);
  
  	buf[0] = size;
  	buf[1] = RPI_FIRMWARE_STATUS_REQUEST;
  	memcpy(&buf[2], data, tag_size);
  	buf[size / 4 - 1] = RPI_FIRMWARE_PROPERTY_END;
  	wmb();
  
  	ret = rpi_firmware_transaction(fw, MBOX_CHAN_PROPERTY, bus_addr);
  
  	rmb();
  	memcpy(data, &buf[2], tag_size);
  	if (ret == 0 && buf[1] != RPI_FIRMWARE_STATUS_SUCCESS) {
  		/*
  		 * The tag name here might not be the one causing the
  		 * error, if there were multiple tags in the request.
  		 * But single-tag is the most common, so go with it.
  		 */
  		dev_err(fw->cl.dev, "Request 0x%08x returned status 0x%08x\n",
  			buf[2], buf[1]);
  		ret = -EINVAL;
  	}
  
  	dma_free_coherent(fw->cl.dev, PAGE_ALIGN(size), buf, bus_addr);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(rpi_firmware_property_list);
  
  /**
   * rpi_firmware_property - Submit single firmware property
   * @fw:		Pointer to firmware structure from rpi_firmware_get().
   * @tag:	One of enum_mbox_property_tag.
   * @tag_data:	Tag data buffer.
   * @buf_size:	Buffer size.
   *
   * Submits a single tag to the VPU firmware through the mailbox
   * property interface.
   *
   * This is a convenience wrapper around
   * rpi_firmware_property_list() to avoid some of the
   * boilerplate in property calls.
   */
  int rpi_firmware_property(struct rpi_firmware *fw,
  			  u32 tag, void *tag_data, size_t buf_size)
  {
  	struct rpi_firmware_property_tag_header *header;
  	int ret;
  
  	/* Some mailboxes can use over 1k bytes. Rather than checking
  	 * size and using stack or kmalloc depending on requirements,
  	 * just use kmalloc. Mailboxes don't get called enough to worry
  	 * too much about the time taken in the allocation.
  	 */
  	void *data = kmalloc(sizeof(*header) + buf_size, GFP_KERNEL);
  
  	if (!data)
  		return -ENOMEM;
  
  	header = data;
  	header->tag = tag;
  	header->buf_size = buf_size;
  	header->req_resp_size = 0;
  	memcpy(data + sizeof(*header), tag_data, buf_size);
  
  	ret = rpi_firmware_property_list(fw, data, buf_size + sizeof(*header));
  
  	memcpy(tag_data, data + sizeof(*header), buf_size);
  
  	kfree(data);
  
  	return ret;
  }
  EXPORT_SYMBOL_GPL(rpi_firmware_property);
  
  static void
  rpi_firmware_print_firmware_revision(struct rpi_firmware *fw)
  {
  	u32 packet;
  	int ret = rpi_firmware_property(fw,
  					RPI_FIRMWARE_GET_FIRMWARE_REVISION,
  					&packet, sizeof(packet));
  
  	if (ret == 0) {
  		struct tm tm;
  
  		time64_to_tm(packet, 0, &tm);
  
  		dev_info(fw->cl.dev,
  			 "Attached to firmware from %04ld-%02d-%02d %02d:%02d\n",
  			 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday,
  			 tm.tm_hour, tm.tm_min);
  	}
  }
  
  static void
  rpi_register_hwmon_driver(struct device *dev, struct rpi_firmware *fw)
  {
  	u32 packet;
  	int ret = rpi_firmware_property(fw, RPI_FIRMWARE_GET_THROTTLED,
  					&packet, sizeof(packet));
  
  	if (ret)
  		return;
  
  	rpi_hwmon = platform_device_register_data(dev, "raspberrypi-hwmon",
  						  -1, NULL, 0);
  }
  
  static int rpi_firmware_probe(struct platform_device *pdev)
  {
  	struct device *dev = &pdev->dev;
  	struct rpi_firmware *fw;
  
  	fw = devm_kzalloc(dev, sizeof(*fw), GFP_KERNEL);
  	if (!fw)
  		return -ENOMEM;
  
  	fw->cl.dev = dev;
  	fw->cl.rx_callback = response_callback;
  	fw->cl.tx_block = true;
  
  	fw->chan = mbox_request_channel(&fw->cl, 0);
  	if (IS_ERR(fw->chan)) {
  		int ret = PTR_ERR(fw->chan);
  		if (ret != -EPROBE_DEFER)
  			dev_err(dev, "Failed to get mbox channel: %d\n", ret);
  		return ret;
  	}
  
  	init_completion(&fw->c);
  
  	platform_set_drvdata(pdev, fw);
  
  	rpi_firmware_print_firmware_revision(fw);
  	rpi_register_hwmon_driver(dev, fw);
  
  	return 0;
  }
  
  static int rpi_firmware_remove(struct platform_device *pdev)
  {
  	struct rpi_firmware *fw = platform_get_drvdata(pdev);
  
  	platform_device_unregister(rpi_hwmon);
  	rpi_hwmon = NULL;
  	mbox_free_channel(fw->chan);
  
  	return 0;
  }
  
  /**
   * rpi_firmware_get - Get pointer to rpi_firmware structure.
   * @firmware_node:    Pointer to the firmware Device Tree node.
   *
   * Returns NULL is the firmware device is not ready.
   */
  struct rpi_firmware *rpi_firmware_get(struct device_node *firmware_node)
  {
  	struct platform_device *pdev = of_find_device_by_node(firmware_node);
  
  	if (!pdev)
  		return NULL;
  
  	return platform_get_drvdata(pdev);
  }
  EXPORT_SYMBOL_GPL(rpi_firmware_get);
  
  static const struct of_device_id rpi_firmware_of_match[] = {
  	{ .compatible = "raspberrypi,bcm2835-firmware", },
  	{},
  };
  MODULE_DEVICE_TABLE(of, rpi_firmware_of_match);
  
  static struct platform_driver rpi_firmware_driver = {
  	.driver = {
  		.name = "raspberrypi-firmware",
  		.of_match_table = rpi_firmware_of_match,
  	},
  	.probe		= rpi_firmware_probe,
  	.remove		= rpi_firmware_remove,
  };
  module_platform_driver(rpi_firmware_driver);
  
  MODULE_AUTHOR("Eric Anholt <eric@anholt.net>");
  MODULE_DESCRIPTION("Raspberry Pi firmware driver");
  MODULE_LICENSE("GPL v2");
  