/*
   *  Bluetooth support for Realtek devices
   *
   *  Copyright (C) 2015 Endless Mobile, Inc.
   *
   *  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; either version 2 of the License, or
   *  (at your option) any later version.
   *
   *  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/module.h>
  #include <linux/firmware.h>
  #include <asm/unaligned.h>
  #include <linux/usb.h>
  
  #include <net/bluetooth/bluetooth.h>
  #include <net/bluetooth/hci_core.h>
  
  #include "btrtl.h"
  
  #define VERSION "0.1"
  
  #define RTL_EPATCH_SIGNATURE	"Realtech"
  #define RTL_ROM_LMP_3499	0x3499
  #define RTL_ROM_LMP_8723A	0x1200
  #define RTL_ROM_LMP_8723B	0x8723
  #define RTL_ROM_LMP_8821A	0x8821
  #define RTL_ROM_LMP_8761A	0x8761
  
  static int rtl_read_rom_version(struct hci_dev *hdev, u8 *version)
  {
  	struct rtl_rom_version_evt *rom_version;
  	struct sk_buff *skb;
  
  	/* Read RTL ROM version command */
  	skb = __hci_cmd_sync(hdev, 0xfc6d, 0, NULL, HCI_INIT_TIMEOUT);
  	if (IS_ERR(skb)) {
  		BT_ERR("%s: Read ROM version failed (%ld)",
  		       hdev->name, PTR_ERR(skb));
  		return PTR_ERR(skb);
  	}
  
  	if (skb->len != sizeof(*rom_version)) {
  		BT_ERR("%s: RTL version event length mismatch", hdev->name);
  		kfree_skb(skb);
  		return -EIO;
  	}
  
  	rom_version = (struct rtl_rom_version_evt *)skb->data;
  	BT_INFO("%s: rom_version status=%x version=%x",
  		hdev->name, rom_version->status, rom_version->version);
  
  	*version = rom_version->version;
  
  	kfree_skb(skb);
  	return 0;
  }
  
  static int rtl8723b_parse_firmware(struct hci_dev *hdev, u16 lmp_subver,
  				   const struct firmware *fw,
  				   unsigned char **_buf)
  {
  	const u8 extension_sig[] = { 0x51, 0x04, 0xfd, 0x77 };
  	struct rtl_epatch_header *epatch_info;
  	unsigned char *buf;
  	int i, ret, len;
  	size_t min_size;
  	u8 opcode, length, data, rom_version = 0;
  	int project_id = -1;
  	const unsigned char *fwptr, *chip_id_base;
  	const unsigned char *patch_length_base, *patch_offset_base;
  	u32 patch_offset = 0;
  	u16 patch_length, num_patches;
  	const u16 project_id_to_lmp_subver[] = {
  		RTL_ROM_LMP_8723A,
  		RTL_ROM_LMP_8723B,
  		RTL_ROM_LMP_8821A,
  		RTL_ROM_LMP_8761A
  	};
  
  	ret = rtl_read_rom_version(hdev, &rom_version);
  	if (ret)
  		return ret;
  
  	min_size = sizeof(struct rtl_epatch_header) + sizeof(extension_sig) + 3;
  	if (fw->size < min_size)
  		return -EINVAL;
  
  	fwptr = fw->data + fw->size - sizeof(extension_sig);
  	if (memcmp(fwptr, extension_sig, sizeof(extension_sig)) != 0) {
  		BT_ERR("%s: extension section signature mismatch", hdev->name);
  		return -EINVAL;
  	}
  
  	/* Loop from the end of the firmware parsing instructions, until
  	 * we find an instruction that identifies the "project ID" for the
  	 * hardware supported by this firwmare file.
  	 * Once we have that, we double-check that that project_id is suitable
  	 * for the hardware we are working with.
  	 */
  	while (fwptr >= fw->data + (sizeof(struct rtl_epatch_header) + 3)) {
  		opcode = *--fwptr;
  		length = *--fwptr;
  		data = *--fwptr;
  
  		BT_DBG("check op=%x len=%x data=%x", opcode, length, data);
  
  		if (opcode == 0xff) /* EOF */
  			break;
  
  		if (length == 0) {
  			BT_ERR("%s: found instruction with length 0",
  			       hdev->name);
  			return -EINVAL;
  		}
  
  		if (opcode == 0 && length == 1) {
  			project_id = data;
  			break;
  		}
  
  		fwptr -= length;
  	}
  
  	if (project_id < 0) {
  		BT_ERR("%s: failed to find version instruction", hdev->name);
  		return -EINVAL;
  	}
  
  	if (project_id >= ARRAY_SIZE(project_id_to_lmp_subver)) {
  		BT_ERR("%s: unknown project id %d", hdev->name, project_id);
  		return -EINVAL;
  	}
  
  	if (lmp_subver != project_id_to_lmp_subver[project_id]) {
  		BT_ERR("%s: firmware is for %x but this is a %x", hdev->name,
  		       project_id_to_lmp_subver[project_id], lmp_subver);
  		return -EINVAL;
  	}
  
  	epatch_info = (struct rtl_epatch_header *)fw->data;
  	if (memcmp(epatch_info->signature, RTL_EPATCH_SIGNATURE, 8) != 0) {
  		BT_ERR("%s: bad EPATCH signature", hdev->name);
  		return -EINVAL;
  	}
  
  	num_patches = le16_to_cpu(epatch_info->num_patches);
  	BT_DBG("fw_version=%x, num_patches=%d",
  	       le32_to_cpu(epatch_info->fw_version), num_patches);
  
  	/* After the rtl_epatch_header there is a funky patch metadata section.
  	 * Assuming 2 patches, the layout is:
  	 * ChipID1 ChipID2 PatchLength1 PatchLength2 PatchOffset1 PatchOffset2
  	 *
  	 * Find the right patch for this chip.
  	 */
  	min_size += 8 * num_patches;
  	if (fw->size < min_size)
  		return -EINVAL;
  
  	chip_id_base = fw->data + sizeof(struct rtl_epatch_header);
  	patch_length_base = chip_id_base + (sizeof(u16) * num_patches);
  	patch_offset_base = patch_length_base + (sizeof(u16) * num_patches);
  	for (i = 0; i < num_patches; i++) {
  		u16 chip_id = get_unaligned_le16(chip_id_base +
  						 (i * sizeof(u16)));
  		if (chip_id == rom_version + 1) {
  			patch_length = get_unaligned_le16(patch_length_base +
  							  (i * sizeof(u16)));
  			patch_offset = get_unaligned_le32(patch_offset_base +
  							  (i * sizeof(u32)));
  			break;
  		}
  	}
  
  	if (!patch_offset) {
  		BT_ERR("%s: didn't find patch for chip id %d",
  		       hdev->name, rom_version);
  		return -EINVAL;
  	}
  
  	BT_DBG("length=%x offset=%x index %d", patch_length, patch_offset, i);
  	min_size = patch_offset + patch_length;
  	if (fw->size < min_size)
  		return -EINVAL;
  
  	/* Copy the firmware into a new buffer and write the version at
  	 * the end.
  	 */
  	len = patch_length;
  	buf = kmemdup(fw->data + patch_offset, patch_length, GFP_KERNEL);
  	if (!buf)
  		return -ENOMEM;
  
  	memcpy(buf + patch_length - 4, &epatch_info->fw_version, 4);
  
  	*_buf = buf;
  	return len;
  }
  
  static int rtl_download_firmware(struct hci_dev *hdev,
  				 const unsigned char *data, int fw_len)
  {
  	struct rtl_download_cmd *dl_cmd;
  	int frag_num = fw_len / RTL_FRAG_LEN + 1;
  	int frag_len = RTL_FRAG_LEN;
  	int ret = 0;
  	int i;
  
  	dl_cmd = kmalloc(sizeof(struct rtl_download_cmd), GFP_KERNEL);
  	if (!dl_cmd)
  		return -ENOMEM;
  
  	for (i = 0; i < frag_num; i++) {
  		struct sk_buff *skb;
  
  		BT_DBG("download fw (%d/%d)", i, frag_num);
  
  		dl_cmd->index = i;
  		if (i == (frag_num - 1)) {
  			dl_cmd->index |= 0x80; /* data end */
  			frag_len = fw_len % RTL_FRAG_LEN;
  		}
  		memcpy(dl_cmd->data, data, frag_len);
  
  		/* Send download command */
  		skb = __hci_cmd_sync(hdev, 0xfc20, frag_len + 1, dl_cmd,
  				     HCI_INIT_TIMEOUT);
  		if (IS_ERR(skb)) {
  			BT_ERR("%s: download fw command failed (%ld)",
  			       hdev->name, PTR_ERR(skb));
  			ret = -PTR_ERR(skb);
  			goto out;
  		}
  
  		if (skb->len != sizeof(struct rtl_download_response)) {
  			BT_ERR("%s: download fw event length mismatch",
  			       hdev->name);
  			kfree_skb(skb);
  			ret = -EIO;
  			goto out;
  		}
  
  		kfree_skb(skb);
  		data += RTL_FRAG_LEN;
  	}
  
  out:
  	kfree(dl_cmd);
  	return ret;
  }
  
  static int btrtl_setup_rtl8723a(struct hci_dev *hdev)
  {
  	const struct firmware *fw;
  	int ret;
  
  	BT_INFO("%s: rtl: loading rtl_bt/rtl8723a_fw.bin", hdev->name);
  	ret = request_firmware(&fw, "rtl_bt/rtl8723a_fw.bin", &hdev->dev);
  	if (ret < 0) {
  		BT_ERR("%s: Failed to load rtl_bt/rtl8723a_fw.bin", hdev->name);
  		return ret;
  	}
  
  	if (fw->size < 8) {
  		ret = -EINVAL;
  		goto out;
  	}
  
  	/* Check that the firmware doesn't have the epatch signature
  	 * (which is only for RTL8723B and newer).
  	 */
  	if (!memcmp(fw->data, RTL_EPATCH_SIGNATURE, 8)) {
  		BT_ERR("%s: unexpected EPATCH signature!", hdev->name);
  		ret = -EINVAL;
  		goto out;
  	}
  
  	ret = rtl_download_firmware(hdev, fw->data, fw->size);
  
  out:
  	release_firmware(fw);
  	return ret;
  }
  
  static int btrtl_setup_rtl8723b(struct hci_dev *hdev, u16 lmp_subver,
  				const char *fw_name)
  {
  	unsigned char *fw_data = NULL;
  	const struct firmware *fw;
  	int ret;
  
  	BT_INFO("%s: rtl: loading %s", hdev->name, fw_name);
  	ret = request_firmware(&fw, fw_name, &hdev->dev);
  	if (ret < 0) {
  		BT_ERR("%s: Failed to load %s", hdev->name, fw_name);
  		return ret;
  	}
  
  	ret = rtl8723b_parse_firmware(hdev, lmp_subver, fw, &fw_data);
  	if (ret < 0)
  		goto out;
  
  	ret = rtl_download_firmware(hdev, fw_data, ret);
  	kfree(fw_data);
  	if (ret < 0)
  		goto out;
  
  out:
  	release_firmware(fw);
  	return ret;
  }
  
  static struct sk_buff *btrtl_read_local_version(struct hci_dev *hdev)
  {
  	struct sk_buff *skb;
  
  	skb = __hci_cmd_sync(hdev, HCI_OP_READ_LOCAL_VERSION, 0, NULL,
  			     HCI_INIT_TIMEOUT);
  	if (IS_ERR(skb)) {
  		BT_ERR("%s: HCI_OP_READ_LOCAL_VERSION failed (%ld)",
  		       hdev->name, PTR_ERR(skb));
  		return skb;
  	}
  
  	if (skb->len != sizeof(struct hci_rp_read_local_version)) {
  		BT_ERR("%s: HCI_OP_READ_LOCAL_VERSION event length mismatch",
  		       hdev->name);
  		kfree_skb(skb);
  		return ERR_PTR(-EIO);
  	}
  
  	return skb;
  }
  
  int btrtl_setup_realtek(struct hci_dev *hdev)
  {
  	struct sk_buff *skb;
  	struct hci_rp_read_local_version *resp;
  	u16 lmp_subver;
  
  	skb = btrtl_read_local_version(hdev);
  	if (IS_ERR(skb))
  		return -PTR_ERR(skb);
  
  	resp = (struct hci_rp_read_local_version *)skb->data;
  	BT_INFO("%s: rtl: examining hci_ver=%02x hci_rev=%04x lmp_ver=%02x "
  		"lmp_subver=%04x", hdev->name, resp->hci_ver, resp->hci_rev,
  		resp->lmp_ver, resp->lmp_subver);
  
  	lmp_subver = le16_to_cpu(resp->lmp_subver);
  	kfree_skb(skb);
  
  	/* Match a set of subver values that correspond to stock firmware,
  	 * which is not compatible with standard btusb.
  	 * If matched, upload an alternative firmware that does conform to
  	 * standard btusb. Once that firmware is uploaded, the subver changes
  	 * to a different value.
  	 */
  	switch (lmp_subver) {
  	case RTL_ROM_LMP_8723A:
  	case RTL_ROM_LMP_3499:
  		return btrtl_setup_rtl8723a(hdev);
  	case RTL_ROM_LMP_8723B:
  		return btrtl_setup_rtl8723b(hdev, lmp_subver,
  					    "rtl_bt/rtl8723b_fw.bin");
  	case RTL_ROM_LMP_8821A:
  		return btrtl_setup_rtl8723b(hdev, lmp_subver,
  					    "rtl_bt/rtl8821a_fw.bin");
  	case RTL_ROM_LMP_8761A:
  		return btrtl_setup_rtl8723b(hdev, lmp_subver,
  					    "rtl_bt/rtl8761a_fw.bin");
  	default:
  		BT_INFO("rtl: assuming no firmware upload needed.");
  		return 0;
  	}
  }
  EXPORT_SYMBOL_GPL(btrtl_setup_realtek);
  
  MODULE_AUTHOR("Daniel Drake <drake@endlessm.com>");
  MODULE_DESCRIPTION("Bluetooth support for Realtek devices ver " VERSION);
  MODULE_VERSION(VERSION);
  MODULE_LICENSE("GPL");