text: /*
   * Function Control Protocol (IEC 61883-1) helper functions
   *
   * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
   * Licensed under the terms of the GNU General Public License, version 2.
   */
  
  #include <linux/device.h>
  #include <linux/firewire.h>
  #include <linux/firewire-constants.h>
  #include <linux/list.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  #include <linux/sched.h>
  #include <linux/spinlock.h>
  #include <linux/wait.h>
  #include <linux/delay.h>
  #include "fcp.h"
  #include "lib.h"
  #include "amdtp.h"
  
  #define CTS_AVC 0x00
  
  #define ERROR_RETRIES	3
  #define ERROR_DELAY_MS	5
  #define FCP_TIMEOUT_MS	125
  
  int avc_general_set_sig_fmt(struct fw_unit *unit, unsigned int rate,
  			    enum avc_general_plug_dir dir,
  			    unsigned short pid)
  {
  	unsigned int sfc;
  	u8 *buf;
  	bool flag;
  	int err;
  
  	flag = false;
  	for (sfc = 0; sfc < CIP_SFC_COUNT; sfc++) {
  		if (amdtp_rate_table[sfc] == rate) {
  			flag = true;
  			break;
  		}
  	}
  	if (!flag)
  		return -EINVAL;
  
  	buf = kzalloc(8, GFP_KERNEL);
  	if (buf == NULL)
  		return -ENOMEM;
  
  	buf[0] = 0x00;		/* AV/C CONTROL */
  	buf[1] = 0xff;		/* UNIT */
  	if (dir == AVC_GENERAL_PLUG_DIR_IN)
  		buf[2] = 0x19;	/* INPUT PLUG SIGNAL FORMAT */
  	else
  		buf[2] = 0x18;	/* OUTPUT PLUG SIGNAL FORMAT */
  	buf[3] = 0xff & pid;	/* plug id */
  	buf[4] = 0x90;		/* EOH_1, Form_1, FMT. AM824 */
  	buf[5] = 0x07 & sfc;	/* FDF-hi. AM824, frequency */
  	buf[6] = 0xff;		/* FDF-mid. AM824, SYT hi (not used)*/
  	buf[7] = 0xff;		/* FDF-low. AM824, SYT lo (not used) */
  
  	/* do transaction and check buf[1-5] are the same against command */
  	err = fcp_avc_transaction(unit, buf, 8, buf, 8,
  				  BIT(1) | BIT(2) | BIT(3) | BIT(4) | BIT(5));
  	if (err >= 0 && err < 8)
  		err = -EIO;
  	else if (buf[0] == 0x08) /* NOT IMPLEMENTED */
  		err = -ENOSYS;
  	else if (buf[0] == 0x0a) /* REJECTED */
  		err = -EINVAL;
  	if (err < 0)
  		goto end;
  
  	err = 0;
  end:
  	kfree(buf);
  	return err;
  }
  EXPORT_SYMBOL(avc_general_set_sig_fmt);
  
  int avc_general_get_sig_fmt(struct fw_unit *unit, unsigned int *rate,
  			    enum avc_general_plug_dir dir,
  			    unsigned short pid)
  {
  	unsigned int sfc;
  	u8 *buf;
  	int err;
  
  	buf = kzalloc(8, GFP_KERNEL);
  	if (buf == NULL)
  		return -ENOMEM;
  
  	buf[0] = 0x01;		/* AV/C STATUS */
  	buf[1] = 0xff;		/* Unit */
  	if (dir == AVC_GENERAL_PLUG_DIR_IN)
  		buf[2] = 0x19;	/* INPUT PLUG SIGNAL FORMAT */
  	else
  		buf[2] = 0x18;	/* OUTPUT PLUG SIGNAL FORMAT */
  	buf[3] = 0xff & pid;	/* plug id */
  	buf[4] = 0x90;		/* EOH_1, Form_1, FMT. AM824 */
  	buf[5] = 0xff;		/* FDF-hi. AM824, frequency */
  	buf[6] = 0xff;		/* FDF-mid. AM824, SYT hi (not used) */
  	buf[7] = 0xff;		/* FDF-low. AM824, SYT lo (not used) */
  
  	/* do transaction and check buf[1-4] are the same against command */
  	err = fcp_avc_transaction(unit, buf, 8, buf, 8,
  				  BIT(1) | BIT(2) | BIT(3) | BIT(4));
  	if (err >= 0 && err < 8)
  		err = -EIO;
  	else if (buf[0] == 0x08) /* NOT IMPLEMENTED */
  		err = -ENOSYS;
  	else if (buf[0] == 0x0a) /* REJECTED */
  		err = -EINVAL;
  	else if (buf[0] == 0x0b) /* IN TRANSITION */
  		err = -EAGAIN;
  	if (err < 0)
  		goto end;
  
  	/* check sfc field and pick up rate */
  	sfc = 0x07 & buf[5];
  	if (sfc >= CIP_SFC_COUNT) {
  		err = -EAGAIN;	/* also in transition */
  		goto end;
  	}
  
  	*rate = amdtp_rate_table[sfc];
  	err = 0;
  end:
  	kfree(buf);
  	return err;
  }
  EXPORT_SYMBOL(avc_general_get_sig_fmt);
  
  int avc_general_get_plug_info(struct fw_unit *unit, unsigned int subunit_type,
  			      unsigned int subunit_id, unsigned int subfunction,
  			      u8 info[AVC_PLUG_INFO_BUF_BYTES])
  {
  	u8 *buf;
  	int err;
  
  	/* extended subunit in spec.4.2 is not supported */
  	if ((subunit_type == 0x1E) || (subunit_id == 5))
  		return -EINVAL;
  
  	buf = kzalloc(8, GFP_KERNEL);
  	if (buf == NULL)
  		return -ENOMEM;
  
  	buf[0] = 0x01;	/* AV/C STATUS */
  	/* UNIT or Subunit, Functionblock */
  	buf[1] = ((subunit_type & 0x1f) << 3) | (subunit_id & 0x7);
  	buf[2] = 0x02;	/* PLUG INFO */
  	buf[3] = 0xff & subfunction;
  
  	err = fcp_avc_transaction(unit, buf, 8, buf, 8, BIT(1) | BIT(2));
  	if (err >= 0 && err < 8)
  		err = -EIO;
  	else if (buf[0] == 0x08) /* NOT IMPLEMENTED */
  		err = -ENOSYS;
  	else if (buf[0] == 0x0a) /* REJECTED */
  		err = -EINVAL;
  	else if (buf[0] == 0x0b) /* IN TRANSITION */
  		err = -EAGAIN;
  	if (err < 0)
  		goto end;
  
  	info[0] = buf[4];
  	info[1] = buf[5];
  	info[2] = buf[6];
  	info[3] = buf[7];
  
  	err = 0;
  end:
  	kfree(buf);
  	return err;
  }
  EXPORT_SYMBOL(avc_general_get_plug_info);
  
  static DEFINE_SPINLOCK(transactions_lock);
  static LIST_HEAD(transactions);
  
  enum fcp_state {
  	STATE_PENDING,
  	STATE_BUS_RESET,
  	STATE_COMPLETE,
  	STATE_DEFERRED,
  };
  
  struct fcp_transaction {
  	struct list_head list;
  	struct fw_unit *unit;
  	void *response_buffer;
  	unsigned int response_size;
  	unsigned int response_match_bytes;
  	enum fcp_state state;
  	wait_queue_head_t wait;
  	bool deferrable;
  };
  
  /**
   * fcp_avc_transaction - send an AV/C command and wait for its response
   * @unit: a unit on the target device
   * @command: a buffer containing the command frame; must be DMA-able
   * @command_size: the size of @command
   * @response: a buffer for the response frame
   * @response_size: the maximum size of @response
   * @response_match_bytes: a bitmap specifying the bytes used to detect the
   *                        correct response frame
   *
   * This function sends a FCP command frame to the target and waits for the
   * corresponding response frame to be returned.
   *
   * Because it is possible for multiple FCP transactions to be active at the
   * same time, the correct response frame is detected by the value of certain
   * bytes.  These bytes must be set in @response before calling this function,
   * and the corresponding bits must be set in @response_match_bytes.
   *
   * @command and @response can point to the same buffer.
   *
   * Returns the actual size of the response frame, or a negative error code.
   */
  int fcp_avc_transaction(struct fw_unit *unit,
  			const void *command, unsigned int command_size,
  			void *response, unsigned int response_size,
  			unsigned int response_match_bytes)
  {
  	struct fcp_transaction t;
  	int tcode, ret, tries = 0;
  
  	t.unit = unit;
  	t.response_buffer = response;
  	t.response_size = response_size;
  	t.response_match_bytes = response_match_bytes;
  	t.state = STATE_PENDING;
  	init_waitqueue_head(&t.wait);
  
  	if (*(const u8 *)command == 0x00 || *(const u8 *)command == 0x03)
  		t.deferrable = true;
  
  	spin_lock_irq(&transactions_lock);
  	list_add_tail(&t.list, &transactions);
  	spin_unlock_irq(&transactions_lock);
  
  	for (;;) {
  		tcode = command_size == 4 ? TCODE_WRITE_QUADLET_REQUEST
  					  : TCODE_WRITE_BLOCK_REQUEST;
  		ret = snd_fw_transaction(t.unit, tcode,
  					 CSR_REGISTER_BASE + CSR_FCP_COMMAND,
  					 (void *)command, command_size, 0);
  		if (ret < 0)
  			break;
  deferred:
  		wait_event_timeout(t.wait, t.state != STATE_PENDING,
  				   msecs_to_jiffies(FCP_TIMEOUT_MS));
  
  		if (t.state == STATE_DEFERRED) {
  			/*
  			 * 'AV/C General Specification' define no time limit
  			 * on command completion once an INTERIM response has
  			 * been sent. but we promise to finish this function
  			 * for a caller. Here we use FCP_TIMEOUT_MS for next
  			 * interval. This is not in the specification.
  			 */
  			t.state = STATE_PENDING;
  			goto deferred;
  		} else if (t.state == STATE_COMPLETE) {
  			ret = t.response_size;
  			break;
  		} else if (t.state == STATE_BUS_RESET) {
  			msleep(ERROR_DELAY_MS);
  		} else if (++tries >= ERROR_RETRIES) {
  			dev_err(&t.unit->device, "FCP command timed out\n");
  			ret = -EIO;
  			break;
  		}
  	}
  
  	spin_lock_irq(&transactions_lock);
  	list_del(&t.list);
  	spin_unlock_irq(&transactions_lock);
  
  	return ret;
  }
  EXPORT_SYMBOL(fcp_avc_transaction);
  
  /**
   * fcp_bus_reset - inform the target handler about a bus reset
   * @unit: the unit that might be used by fcp_avc_transaction()
   *
   * This function must be called from the driver's .update handler to inform
   * the FCP transaction handler that a bus reset has happened.  Any pending FCP
   * transactions are retried.
   */
  void fcp_bus_reset(struct fw_unit *unit)
  {
  	struct fcp_transaction *t;
  
  	spin_lock_irq(&transactions_lock);
  	list_for_each_entry(t, &transactions, list) {
  		if (t->unit == unit &&
  		    (t->state == STATE_PENDING ||
  		     t->state == STATE_DEFERRED)) {
  			t->state = STATE_BUS_RESET;
  			wake_up(&t->wait);
  		}
  	}
  	spin_unlock_irq(&transactions_lock);
  }
  EXPORT_SYMBOL(fcp_bus_reset);
  
  /* checks whether the response matches the masked bytes in response_buffer */
  static bool is_matching_response(struct fcp_transaction *transaction,
  				 const void *response, size_t length)
  {
  	const u8 *p1, *p2;
  	unsigned int mask, i;
  
  	p1 = response;
  	p2 = transaction->response_buffer;
  	mask = transaction->response_match_bytes;
  
  	for (i = 0; ; ++i) {
  		if ((mask & 1) && p1[i] != p2[i])
  			return false;
  		mask >>= 1;
  		if (!mask)
  			return true;
  		if (--length == 0)
  			return false;
  	}
  }
  
  static void fcp_response(struct fw_card *card, struct fw_request *request,
  			 int tcode, int destination, int source,
  			 int generation, unsigned long long offset,
  			 void *data, size_t length, void *callback_data)
  {
  	struct fcp_transaction *t;
  	unsigned long flags;
  
  	if (length < 1 || (*(const u8 *)data & 0xf0) != CTS_AVC)
  		return;
  
  	spin_lock_irqsave(&transactions_lock, flags);
  	list_for_each_entry(t, &transactions, list) {
  		struct fw_device *device = fw_parent_device(t->unit);
  		if (device->card != card ||
  		    device->generation != generation)
  			continue;
  		smp_rmb(); /* node_id vs. generation */
  		if (device->node_id != source)
  			continue;
  
  		if (t->state == STATE_PENDING &&
  		    is_matching_response(t, data, length)) {
  			if (t->deferrable && *(const u8 *)data == 0x0f) {
  				t->state = STATE_DEFERRED;
  			} else {
  				t->state = STATE_COMPLETE;
  				t->response_size = min_t(unsigned int, length,
  							 t->response_size);
  				memcpy(t->response_buffer, data,
  				       t->response_size);
  			}
  			wake_up(&t->wait);
  		}
  	}
  	spin_unlock_irqrestore(&transactions_lock, flags);
  }
  
  static struct fw_address_handler response_register_handler = {
  	.length = 0x200,
  	.address_callback = fcp_response,
  };
  
  static int __init fcp_module_init(void)
  {
  	static const struct fw_address_region response_register_region = {
  		.start = CSR_REGISTER_BASE + CSR_FCP_RESPONSE,
  		.end = CSR_REGISTER_BASE + CSR_FCP_END,
  	};
  
  	fw_core_add_address_handler(&response_register_handler,
  				    &response_register_region);
  
  	return 0;
  }
  
  static void __exit fcp_module_exit(void)
  {
  	WARN_ON(!list_empty(&transactions));
  	fw_core_remove_address_handler(&response_register_handler);
  }
  
  module_init(fcp_module_init);
  module_exit(fcp_module_exit);
  