/*
   * PowerMac G5 SMU driver
   *
   * Copyright 2004 J. Mayer <l_indien@magic.fr>
   * Copyright 2005 Benjamin Herrenschmidt, IBM Corp.
   *
   * Released under the term of the GNU GPL v2.
   */
  
  /*

   * TODO:

   *  - maybe add timeout to commands ?
   *  - blocking version of time functions
   *  - polling version of i2c commands (including timer that works with

   *    interrupts off)

   *  - maybe avoid some data copies with i2c by directly using the smu cmd
   *    buffer and a lower level internal interface
   *  - understand SMU -> CPU events and implement reception of them via
   *    the userland interface

   */

  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/device.h>
  #include <linux/dmapool.h>
  #include <linux/bootmem.h>
  #include <linux/vmalloc.h>
  #include <linux/highmem.h>
  #include <linux/jiffies.h>
  #include <linux/interrupt.h>
  #include <linux/rtc.h>

  #include <linux/completion.h>
  #include <linux/miscdevice.h>
  #include <linux/delay.h>

  #include <linux/poll.h>

  #include <linux/mutex.h>

  #include <linux/of_device.h>
  #include <linux/of_platform.h>

  #include <linux/slab.h>

  
  #include <asm/byteorder.h>
  #include <asm/io.h>
  #include <asm/prom.h>
  #include <asm/machdep.h>
  #include <asm/pmac_feature.h>
  #include <asm/smu.h>
  #include <asm/sections.h>
  #include <asm/abs_addr.h>

  #include <asm/uaccess.h>

  #define VERSION "0.7"

  #define AUTHOR  "(c) 2005 Benjamin Herrenschmidt, IBM Corp."

  #undef DEBUG_SMU

  
  #ifdef DEBUG_SMU

  #define DPRINTK(fmt, args...) do { printk(KERN_DEBUG fmt , ##args); } while (0)

  #else
  #define DPRINTK(fmt, args...) do { } while (0)
  #endif
  
  /*
   * This is the command buffer passed to the SMU hardware
   */

  #define SMU_MAX_DATA	254

  struct smu_cmd_buf {
  	u8 cmd;
  	u8 length;

  	u8 data[SMU_MAX_DATA];

  };
  
  struct smu_device {
  	spinlock_t		lock;
  	struct device_node	*of_node;

  	struct platform_device	*of_dev;

  	int			doorbell;	/* doorbell gpio */

  	u32 __iomem		*db_buf;	/* doorbell buffer */

  	struct device_node	*db_node;
  	unsigned int		db_irq;

  	int			msg;

  	struct device_node	*msg_node;
  	unsigned int		msg_irq;

  	struct smu_cmd_buf	*cmd_buf;	/* command buffer virtual */
  	u32			cmd_buf_abs;	/* command buffer absolute */

  	struct list_head	cmd_list;
  	struct smu_cmd		*cmd_cur;	/* pending command */

  	int			broken_nap;

  	struct list_head	cmd_i2c_list;
  	struct smu_i2c_cmd	*cmd_i2c_cur;	/* pending i2c command */
  	struct timer_list	i2c_timer;

  };
  
  /*
   * I don't think there will ever be more than one SMU, so
   * for now, just hard code that
   */

  static DEFINE_MUTEX(smu_mutex);

  static struct smu_device	*smu;

  static DEFINE_MUTEX(smu_part_access);

  static int smu_irq_inited;

  static void smu_i2c_retry(unsigned long data);

  /*

   * SMU driver low level stuff

   */

  static void smu_start_cmd(void)

  {

  	unsigned long faddr, fend;
  	struct smu_cmd *cmd;

  	if (list_empty(&smu->cmd_list))
  		return;
  
  	/* Fetch first command in queue */
  	cmd = list_entry(smu->cmd_list.next, struct smu_cmd, link);
  	smu->cmd_cur = cmd;
  	list_del(&cmd->link);
  
  	DPRINTK("SMU: starting cmd %x, %d bytes data
  ", cmd->cmd,
  		cmd->data_len);

  	DPRINTK("SMU: data buffer: %02x %02x %02x %02x %02x %02x %02x %02x
  ",

  		((u8 *)cmd->data_buf)[0], ((u8 *)cmd->data_buf)[1],

  		((u8 *)cmd->data_buf)[2], ((u8 *)cmd->data_buf)[3],
  		((u8 *)cmd->data_buf)[4], ((u8 *)cmd->data_buf)[5],
  		((u8 *)cmd->data_buf)[6], ((u8 *)cmd->data_buf)[7]);

  
  	/* Fill the SMU command buffer */
  	smu->cmd_buf->cmd = cmd->cmd;
  	smu->cmd_buf->length = cmd->data_len;
  	memcpy(smu->cmd_buf->data, cmd->data_buf, cmd->data_len);
  
  	/* Flush command and data to RAM */
  	faddr = (unsigned long)smu->cmd_buf;
  	fend = faddr + smu->cmd_buf->length + 2;
  	flush_inval_dcache_range(faddr, fend);

  
  	/* We also disable NAP mode for the duration of the command
  	 * on U3 based machines.
  	 * This is slightly racy as it can be written back to 1 by a sysctl
  	 * but that never happens in practice. There seem to be an issue with
  	 * U3 based machines such as the iMac G5 where napping for the
  	 * whole duration of the command prevents the SMU from fetching it
  	 * from memory. This might be related to the strange i2c based
  	 * mechanism the SMU uses to access memory.
  	 */
  	if (smu->broken_nap)
  		powersave_nap = 0;

  	/* This isn't exactly a DMA mapping here, I suspect

  	 * the SMU is actually communicating with us via i2c to the
  	 * northbridge or the CPU to access RAM.
  	 */

  	writel(smu->cmd_buf_abs, smu->db_buf);

  
  	/* Ring the SMU doorbell */

  	pmac_do_feature_call(PMAC_FTR_WRITE_GPIO, NULL, smu->doorbell, 4);

  }

  static irqreturn_t smu_db_intr(int irq, void *arg)

  {

  	unsigned long flags;
  	struct smu_cmd *cmd;
  	void (*done)(struct smu_cmd *cmd, void *misc) = NULL;
  	void *misc = NULL;
  	u8 gpio;
  	int rc = 0;

  	/* SMU completed the command, well, we hope, let's make sure
  	 * of it
  	 */
  	spin_lock_irqsave(&smu->lock, flags);

  	gpio = pmac_do_feature_call(PMAC_FTR_READ_GPIO, NULL, smu->doorbell);

  	if ((gpio & 7) != 7) {
  		spin_unlock_irqrestore(&smu->lock, flags);

  		return IRQ_HANDLED;

  	}

  
  	cmd = smu->cmd_cur;
  	smu->cmd_cur = NULL;
  	if (cmd == NULL)
  		goto bail;
  
  	if (rc == 0) {
  		unsigned long faddr;
  		int reply_len;
  		u8 ack;
  
  		/* CPU might have brought back the cache line, so we need
  		 * to flush again before peeking at the SMU response. We
  		 * flush the entire buffer for now as we haven't read the

  		 * reply length (it's only 2 cache lines anyway)

  		 */
  		faddr = (unsigned long)smu->cmd_buf;
  		flush_inval_dcache_range(faddr, faddr + 256);
  
  		/* Now check ack */
  		ack = (~cmd->cmd) & 0xff;
  		if (ack != smu->cmd_buf->cmd) {
  			DPRINTK("SMU: incorrect ack, want %x got %x
  ",
  				ack, smu->cmd_buf->cmd);
  			rc = -EIO;
  		}
  		reply_len = rc == 0 ? smu->cmd_buf->length : 0;
  		DPRINTK("SMU: reply len: %d
  ", reply_len);
  		if (reply_len > cmd->reply_len) {
  			printk(KERN_WARNING "SMU: reply buffer too small,"
  			       "got %d bytes for a %d bytes buffer
  ",
  			       reply_len, cmd->reply_len);
  			reply_len = cmd->reply_len;
  		}
  		cmd->reply_len = reply_len;
  		if (cmd->reply_buf && reply_len)
  			memcpy(cmd->reply_buf, smu->cmd_buf->data, reply_len);
  	}
  
  	/* Now complete the command. Write status last in order as we lost
  	 * ownership of the command structure as soon as it's no longer -1
  	 */
  	done = cmd->done;
  	misc = cmd->misc;
  	mb();
  	cmd->status = rc;

  
  	/* Re-enable NAP mode */
  	if (smu->broken_nap)
  		powersave_nap = 1;

   bail:
  	/* Start next command if any */
  	smu_start_cmd();
  	spin_unlock_irqrestore(&smu->lock, flags);
  
  	/* Call command completion handler if any */
  	if (done)
  		done(cmd, misc);
  
  	/* It's an edge interrupt, nothing to do */
  	return IRQ_HANDLED;

  }

  static irqreturn_t smu_msg_intr(int irq, void *arg)

  {

  	/* I don't quite know what to do with this one, we seem to never
  	 * receive it, so I suspect we have to arm it someway in the SMU
  	 * to start getting events that way.
  	 */
  
  	printk(KERN_INFO "SMU: message interrupt !
  ");

  	/* It's an edge interrupt, nothing to do */
  	return IRQ_HANDLED;
  }

  /*
   * Queued command management.
   *
   */

  int smu_queue_cmd(struct smu_cmd *cmd)
  {
  	unsigned long flags;

  	if (smu == NULL)
  		return -ENODEV;
  	if (cmd->data_len > SMU_MAX_DATA ||
  	    cmd->reply_len > SMU_MAX_DATA)
  		return -EINVAL;
  
  	cmd->status = 1;
  	spin_lock_irqsave(&smu->lock, flags);
  	list_add_tail(&cmd->link, &smu->cmd_list);
  	if (smu->cmd_cur == NULL)
  		smu_start_cmd();
  	spin_unlock_irqrestore(&smu->lock, flags);

  	/* Workaround for early calls when irq isn't available */
  	if (!smu_irq_inited || smu->db_irq == NO_IRQ)
  		smu_spinwait_cmd(cmd);

  	return 0;

  }

  EXPORT_SYMBOL(smu_queue_cmd);

  
  int smu_queue_simple(struct smu_simple_cmd *scmd, u8 command,
  		     unsigned int data_len,
  		     void (*done)(struct smu_cmd *cmd, void *misc),
  		     void *misc, ...)

  {

  	struct smu_cmd *cmd = &scmd->cmd;
  	va_list list;
  	int i;
  
  	if (data_len > sizeof(scmd->buffer))
  		return -EINVAL;
  
  	memset(scmd, 0, sizeof(*scmd));
  	cmd->cmd = command;
  	cmd->data_len = data_len;
  	cmd->data_buf = scmd->buffer;
  	cmd->reply_len = sizeof(scmd->buffer);
  	cmd->reply_buf = scmd->buffer;
  	cmd->done = done;
  	cmd->misc = misc;
  
  	va_start(list, misc);
  	for (i = 0; i < data_len; ++i)
  		scmd->buffer[i] = (u8)va_arg(list, int);
  	va_end(list);
  
  	return smu_queue_cmd(cmd);

  }

  EXPORT_SYMBOL(smu_queue_simple);

  
  void smu_poll(void)

  {

  	u8 gpio;
  
  	if (smu == NULL)
  		return;
  
  	gpio = pmac_do_feature_call(PMAC_FTR_READ_GPIO, NULL, smu->doorbell);
  	if ((gpio & 7) == 7)

  		smu_db_intr(smu->db_irq, smu);

  }

  EXPORT_SYMBOL(smu_poll);

  void smu_done_complete(struct smu_cmd *cmd, void *misc)

  {

  	struct completion *comp = misc;
  
  	complete(comp);

  }

  EXPORT_SYMBOL(smu_done_complete);

  void smu_spinwait_cmd(struct smu_cmd *cmd)

  {

  	while(cmd->status == 1)
  		smu_poll();
  }
  EXPORT_SYMBOL(smu_spinwait_cmd);
  
  
  /* RTC low level commands */
  static inline int bcd2hex (int n)
  {
  	return (((n & 0xf0) >> 4) * 10) + (n & 0xf);

  }

  
  static inline int hex2bcd (int n)

  {

  	return ((n / 10) << 4) + (n % 10);

  }

  
  static inline void smu_fill_set_rtc_cmd(struct smu_cmd_buf *cmd_buf,
  					struct rtc_time *time)
  {
  	cmd_buf->cmd = 0x8e;
  	cmd_buf->length = 8;
  	cmd_buf->data[0] = 0x80;
  	cmd_buf->data[1] = hex2bcd(time->tm_sec);
  	cmd_buf->data[2] = hex2bcd(time->tm_min);
  	cmd_buf->data[3] = hex2bcd(time->tm_hour);
  	cmd_buf->data[4] = time->tm_wday;
  	cmd_buf->data[5] = hex2bcd(time->tm_mday);
  	cmd_buf->data[6] = hex2bcd(time->tm_mon) + 1;
  	cmd_buf->data[7] = hex2bcd(time->tm_year - 100);
  }

  int smu_get_rtc_time(struct rtc_time *time, int spinwait)

  {

  	struct smu_simple_cmd cmd;

  	int rc;
  
  	if (smu == NULL)
  		return -ENODEV;
  
  	memset(time, 0, sizeof(struct rtc_time));

  	rc = smu_queue_simple(&cmd, SMU_CMD_RTC_COMMAND, 1, NULL, NULL,
  			      SMU_CMD_RTC_GET_DATETIME);
  	if (rc)
  		return rc;
  	smu_spinwait_simple(&cmd);

  	time->tm_sec = bcd2hex(cmd.buffer[0]);
  	time->tm_min = bcd2hex(cmd.buffer[1]);
  	time->tm_hour = bcd2hex(cmd.buffer[2]);
  	time->tm_wday = bcd2hex(cmd.buffer[3]);
  	time->tm_mday = bcd2hex(cmd.buffer[4]);
  	time->tm_mon = bcd2hex(cmd.buffer[5]) - 1;
  	time->tm_year = bcd2hex(cmd.buffer[6]) + 100;
  
  	return 0;

  }

  
  int smu_set_rtc_time(struct rtc_time *time, int spinwait)

  {

  	struct smu_simple_cmd cmd;

  	int rc;
  
  	if (smu == NULL)
  		return -ENODEV;

  	rc = smu_queue_simple(&cmd, SMU_CMD_RTC_COMMAND, 8, NULL, NULL,
  			      SMU_CMD_RTC_SET_DATETIME,
  			      hex2bcd(time->tm_sec),
  			      hex2bcd(time->tm_min),
  			      hex2bcd(time->tm_hour),
  			      time->tm_wday,
  			      hex2bcd(time->tm_mday),
  			      hex2bcd(time->tm_mon) + 1,
  			      hex2bcd(time->tm_year - 100));
  	if (rc)
  		return rc;
  	smu_spinwait_simple(&cmd);

  	return 0;

  }

  void smu_shutdown(void)
  {

  	struct smu_simple_cmd cmd;

  
  	if (smu == NULL)
  		return;

  	if (smu_queue_simple(&cmd, SMU_CMD_POWER_COMMAND, 9, NULL, NULL,
  			     'S', 'H', 'U', 'T', 'D', 'O', 'W', 'N', 0))
  		return;
  	smu_spinwait_simple(&cmd);

  	for (;;)
  		;

  }

  void smu_restart(void)
  {

  	struct smu_simple_cmd cmd;

  
  	if (smu == NULL)
  		return;

  	if (smu_queue_simple(&cmd, SMU_CMD_POWER_COMMAND, 8, NULL, NULL,
  			     'R', 'E', 'S', 'T', 'A', 'R', 'T', 0))
  		return;
  	smu_spinwait_simple(&cmd);

  	for (;;)
  		;

  }

  int smu_present(void)
  {
  	return smu != NULL;
  }

  EXPORT_SYMBOL(smu_present);

  int __init smu_init (void)

  {
  	struct device_node *np;

  	const u32 *data;

  	int ret = 0;

  
          np = of_find_node_by_type(NULL, "smu");
          if (np == NULL)
  		return -ENODEV;

  	printk(KERN_INFO "SMU: Driver %s %s
  ", VERSION, AUTHOR);

  	if (smu_cmdbuf_abs == 0) {
  		printk(KERN_ERR "SMU: Command buffer not allocated !
  ");

  		ret = -EINVAL;
  		goto fail_np;

  	}
  
  	smu = alloc_bootmem(sizeof(struct smu_device));

  
  	spin_lock_init(&smu->lock);

  	INIT_LIST_HEAD(&smu->cmd_list);
  	INIT_LIST_HEAD(&smu->cmd_i2c_list);

  	smu->of_node = np;

  	smu->db_irq = NO_IRQ;
  	smu->msg_irq = NO_IRQ;

  	/* smu_cmdbuf_abs is in the low 2G of RAM, can be converted to a
  	 * 32 bits value safely
  	 */
  	smu->cmd_buf_abs = (u32)smu_cmdbuf_abs;
  	smu->cmd_buf = (struct smu_cmd_buf *)abs_to_virt(smu_cmdbuf_abs);

  	smu->db_node = of_find_node_by_name(NULL, "smu-doorbell");
  	if (smu->db_node == NULL) {

  		printk(KERN_ERR "SMU: Can't find doorbell GPIO !
  ");

  		ret = -ENXIO;
  		goto fail_bootmem;

  	}

  	data = of_get_property(smu->db_node, "reg", NULL);

  	if (data == NULL) {
  		printk(KERN_ERR "SMU: Can't find doorbell GPIO address !
  ");

  		ret = -ENXIO;
  		goto fail_db_node;

  	}
  
  	/* Current setup has one doorbell GPIO that does both doorbell
  	 * and ack. GPIOs are at 0x50, best would be to find that out
  	 * in the device-tree though.
  	 */

  	smu->doorbell = *data;
  	if (smu->doorbell < 0x50)
  		smu->doorbell += 0x50;

  
  	/* Now look for the smu-interrupt GPIO */
  	do {

  		smu->msg_node = of_find_node_by_name(NULL, "smu-interrupt");
  		if (smu->msg_node == NULL)

  			break;

  		data = of_get_property(smu->msg_node, "reg", NULL);

  		if (data == NULL) {

  			of_node_put(smu->msg_node);
  			smu->msg_node = NULL;

  			break;
  		}
  		smu->msg = *data;
  		if (smu->msg < 0x50)
  			smu->msg += 0x50;

  	} while(0);

  
  	/* Doorbell buffer is currently hard-coded, I didn't find a proper
  	 * device-tree entry giving the address. Best would probably to use
  	 * an offset for K2 base though, but let's do it that way for now.
  	 */
  	smu->db_buf = ioremap(0x8000860c, 0x1000);
  	if (smu->db_buf == NULL) {
  		printk(KERN_ERR "SMU: Can't map doorbell buffer pointer !
  ");

  		ret = -ENXIO;
  		goto fail_msg_node;

  	}

  	/* U3 has an issue with NAP mode when issuing SMU commands */
  	smu->broken_nap = pmac_get_uninorth_variant() < 4;
  	if (smu->broken_nap)
  		printk(KERN_INFO "SMU: using NAP mode workaround
  ");

  	sys_ctrler = SYS_CTRLER_SMU;
  	return 0;

  fail_msg_node:
  	if (smu->msg_node)
  		of_node_put(smu->msg_node);
  fail_db_node:
  	of_node_put(smu->db_node);
  fail_bootmem:
  	free_bootmem((unsigned long)smu, sizeof(struct smu_device));

  	smu = NULL;

  fail_np:
  	of_node_put(np);
  	return ret;

  }

  
  
  static int smu_late_init(void)
  {
  	if (!smu)
  		return 0;

  	init_timer(&smu->i2c_timer);
  	smu->i2c_timer.function = smu_i2c_retry;
  	smu->i2c_timer.data = (unsigned long)smu;

  	if (smu->db_node) {
  		smu->db_irq = irq_of_parse_and_map(smu->db_node, 0);
  		if (smu->db_irq == NO_IRQ)
  			printk(KERN_ERR "smu: failed to map irq for node %s
  ",
  			       smu->db_node->full_name);
  	}
  	if (smu->msg_node) {
  		smu->msg_irq = irq_of_parse_and_map(smu->msg_node, 0);
  		if (smu->msg_irq == NO_IRQ)
  			printk(KERN_ERR "smu: failed to map irq for node %s
  ",
  			       smu->msg_node->full_name);
  	}

  	/*
  	 * Try to request the interrupts
  	 */
  
  	if (smu->db_irq != NO_IRQ) {
  		if (request_irq(smu->db_irq, smu_db_intr,

  				IRQF_SHARED, "SMU doorbell", smu) < 0) {

  			printk(KERN_WARNING "SMU: can't "
  			       "request interrupt %d
  ",
  			       smu->db_irq);
  			smu->db_irq = NO_IRQ;
  		}
  	}
  
  	if (smu->msg_irq != NO_IRQ) {
  		if (request_irq(smu->msg_irq, smu_msg_intr,

  				IRQF_SHARED, "SMU message", smu) < 0) {

  			printk(KERN_WARNING "SMU: can't "
  			       "request interrupt %d
  ",
  			       smu->msg_irq);
  			smu->msg_irq = NO_IRQ;
  		}
  	}

  	smu_irq_inited = 1;

  	return 0;
  }

  /* This has to be before arch_initcall as the low i2c stuff relies on the
   * above having been done before we reach arch_initcalls
   */
  core_initcall(smu_late_init);

  
  /*
   * sysfs visibility
   */

  static void smu_expose_childs(struct work_struct *unused)

  {

  	struct device_node *np;
  
  	for (np = NULL; (np = of_get_next_child(smu->of_node, np)) != NULL;)

  		if (of_device_is_compatible(np, "smu-sensors"))

  			of_platform_device_create(np, "smu-sensors",
  						  &smu->of_dev->dev);

  }

  static DECLARE_WORK(smu_expose_childs_work, smu_expose_childs);

  static int smu_platform_probe(struct platform_device* dev)

  {
  	if (!smu)
  		return -ENODEV;
  	smu->of_dev = dev;
  
  	/*
  	 * Ok, we are matched, now expose all i2c busses. We have to defer
  	 * that unfortunately or it would deadlock inside the device model
  	 */
  	schedule_work(&smu_expose_childs_work);
  
  	return 0;
  }

  static const struct of_device_id smu_platform_match[] =

  {
  	{
  		.type		= "smu",
  	},
  	{},
  };

  static struct platform_driver smu_of_platform_driver =

  {

  	.driver = {
  		.name = "smu",
  		.owner = THIS_MODULE,
  		.of_match_table = smu_platform_match,
  	},

  	.probe		= smu_platform_probe,
  };
  
  static int __init smu_init_sysfs(void)
  {

  	/*

  	 * For now, we don't power manage machines with an SMU chip,
  	 * I'm a bit too far from figuring out how that works with those
  	 * new chipsets, but that will come back and bite us
  	 */

  	platform_driver_register(&smu_of_platform_driver);

  	return 0;
  }
  
  device_initcall(smu_init_sysfs);

  struct platform_device *smu_get_ofdev(void)

  {
  	if (!smu)
  		return NULL;
  	return smu->of_dev;
  }
  
  EXPORT_SYMBOL_GPL(smu_get_ofdev);
  
  /*
   * i2c interface
   */
  
  static void smu_i2c_complete_command(struct smu_i2c_cmd *cmd, int fail)
  {
  	void (*done)(struct smu_i2c_cmd *cmd, void *misc) = cmd->done;
  	void *misc = cmd->misc;
  	unsigned long flags;
  
  	/* Check for read case */
  	if (!fail && cmd->read) {
  		if (cmd->pdata[0] < 1)
  			fail = 1;
  		else
  			memcpy(cmd->info.data, &cmd->pdata[1],
  			       cmd->info.datalen);
  	}
  
  	DPRINTK("SMU: completing, success: %d
  ", !fail);
  
  	/* Update status and mark no pending i2c command with lock
  	 * held so nobody comes in while we dequeue an eventual
  	 * pending next i2c command
  	 */
  	spin_lock_irqsave(&smu->lock, flags);
  	smu->cmd_i2c_cur = NULL;
  	wmb();
  	cmd->status = fail ? -EIO : 0;
  
  	/* Is there another i2c command waiting ? */
  	if (!list_empty(&smu->cmd_i2c_list)) {
  		struct smu_i2c_cmd *newcmd;
  
  		/* Fetch it, new current, remove from list */
  		newcmd = list_entry(smu->cmd_i2c_list.next,
  				    struct smu_i2c_cmd, link);
  		smu->cmd_i2c_cur = newcmd;
  		list_del(&cmd->link);
  
  		/* Queue with low level smu */
  		list_add_tail(&cmd->scmd.link, &smu->cmd_list);
  		if (smu->cmd_cur == NULL)
  			smu_start_cmd();
  	}
  	spin_unlock_irqrestore(&smu->lock, flags);
  
  	/* Call command completion handler if any */
  	if (done)
  		done(cmd, misc);
  
  }
  
  
  static void smu_i2c_retry(unsigned long data)
  {

  	struct smu_i2c_cmd	*cmd = smu->cmd_i2c_cur;

  
  	DPRINTK("SMU: i2c failure, requeuing...
  ");
  
  	/* requeue command simply by resetting reply_len */
  	cmd->pdata[0] = 0xff;

  	cmd->scmd.reply_len = sizeof(cmd->pdata);

  	smu_queue_cmd(&cmd->scmd);
  }
  
  
  static void smu_i2c_low_completion(struct smu_cmd *scmd, void *misc)
  {
  	struct smu_i2c_cmd	*cmd = misc;
  	int			fail = 0;
  
  	DPRINTK("SMU: i2c compl. stage=%d status=%x pdata[0]=%x rlen: %x
  ",
  		cmd->stage, scmd->status, cmd->pdata[0], scmd->reply_len);
  
  	/* Check for possible status */
  	if (scmd->status < 0)
  		fail = 1;
  	else if (cmd->read) {
  		if (cmd->stage == 0)
  			fail = cmd->pdata[0] != 0;
  		else
  			fail = cmd->pdata[0] >= 0x80;
  	} else {
  		fail = cmd->pdata[0] != 0;
  	}
  
  	/* Handle failures by requeuing command, after 5ms interval
  	 */
  	if (fail && --cmd->retries > 0) {
  		DPRINTK("SMU: i2c failure, starting timer...
  ");

  		BUG_ON(cmd != smu->cmd_i2c_cur);

  		if (!smu_irq_inited) {
  			mdelay(5);
  			smu_i2c_retry(0);
  			return;
  		}

  		mod_timer(&smu->i2c_timer, jiffies + msecs_to_jiffies(5));

  		return;
  	}
  
  	/* If failure or stage 1, command is complete */
  	if (fail || cmd->stage != 0) {
  		smu_i2c_complete_command(cmd, fail);
  		return;
  	}
  
  	DPRINTK("SMU: going to stage 1
  ");
  
  	/* Ok, initial command complete, now poll status */
  	scmd->reply_buf = cmd->pdata;

  	scmd->reply_len = sizeof(cmd->pdata);

  	scmd->data_buf = cmd->pdata;
  	scmd->data_len = 1;
  	cmd->pdata[0] = 0;
  	cmd->stage = 1;
  	cmd->retries = 20;
  	smu_queue_cmd(scmd);
  }
  
  
  int smu_queue_i2c(struct smu_i2c_cmd *cmd)
  {
  	unsigned long flags;
  
  	if (smu == NULL)
  		return -ENODEV;
  
  	/* Fill most fields of scmd */
  	cmd->scmd.cmd = SMU_CMD_I2C_COMMAND;
  	cmd->scmd.done = smu_i2c_low_completion;
  	cmd->scmd.misc = cmd;
  	cmd->scmd.reply_buf = cmd->pdata;

  	cmd->scmd.reply_len = sizeof(cmd->pdata);

  	cmd->scmd.data_buf = (u8 *)(char *)&cmd->info;
  	cmd->scmd.status = 1;
  	cmd->stage = 0;
  	cmd->pdata[0] = 0xff;
  	cmd->retries = 20;
  	cmd->status = 1;
  
  	/* Check transfer type, sanitize some "info" fields
  	 * based on transfer type and do more checking
  	 */
  	cmd->info.caddr = cmd->info.devaddr;
  	cmd->read = cmd->info.devaddr & 0x01;
  	switch(cmd->info.type) {
  	case SMU_I2C_TRANSFER_SIMPLE:
  		memset(&cmd->info.sublen, 0, 4);
  		break;
  	case SMU_I2C_TRANSFER_COMBINED:
  		cmd->info.devaddr &= 0xfe;
  	case SMU_I2C_TRANSFER_STDSUB:
  		if (cmd->info.sublen > 3)
  			return -EINVAL;
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	/* Finish setting up command based on transfer direction
  	 */
  	if (cmd->read) {
  		if (cmd->info.datalen > SMU_I2C_READ_MAX)
  			return -EINVAL;
  		memset(cmd->info.data, 0xff, cmd->info.datalen);
  		cmd->scmd.data_len = 9;
  	} else {
  		if (cmd->info.datalen > SMU_I2C_WRITE_MAX)
  			return -EINVAL;
  		cmd->scmd.data_len = 9 + cmd->info.datalen;
  	}
  
  	DPRINTK("SMU: i2c enqueuing command
  ");
  	DPRINTK("SMU:   %s, len=%d bus=%x addr=%x sub0=%x type=%x
  ",
  		cmd->read ? "read" : "write", cmd->info.datalen,
  		cmd->info.bus, cmd->info.caddr,
  		cmd->info.subaddr[0], cmd->info.type);
  
  
  	/* Enqueue command in i2c list, and if empty, enqueue also in
  	 * main command list
  	 */
  	spin_lock_irqsave(&smu->lock, flags);
  	if (smu->cmd_i2c_cur == NULL) {
  		smu->cmd_i2c_cur = cmd;
  		list_add_tail(&cmd->scmd.link, &smu->cmd_list);
  		if (smu->cmd_cur == NULL)
  			smu_start_cmd();
  	} else
  		list_add_tail(&cmd->link, &smu->cmd_i2c_list);
  	spin_unlock_irqrestore(&smu->lock, flags);
  
  	return 0;
  }

  /*
   * Handling of "partitions"
   */
  
  static int smu_read_datablock(u8 *dest, unsigned int addr, unsigned int len)
  {

  	DECLARE_COMPLETION_ONSTACK(comp);

  	unsigned int chunk;
  	struct smu_cmd cmd;
  	int rc;
  	u8 params[8];
  
  	/* We currently use a chunk size of 0xe. We could check the
  	 * SMU firmware version and use bigger sizes though
  	 */
  	chunk = 0xe;
  
  	while (len) {
  		unsigned int clen = min(len, chunk);
  
  		cmd.cmd = SMU_CMD_MISC_ee_COMMAND;
  		cmd.data_len = 7;
  		cmd.data_buf = params;
  		cmd.reply_len = chunk;
  		cmd.reply_buf = dest;
  		cmd.done = smu_done_complete;
  		cmd.misc = ∁
  		params[0] = SMU_CMD_MISC_ee_GET_DATABLOCK_REC;
  		params[1] = 0x4;
  		*((u32 *)&params[2]) = addr;
  		params[6] = clen;
  
  		rc = smu_queue_cmd(&cmd);
  		if (rc)
  			return rc;
  		wait_for_completion(&comp);
  		if (cmd.status != 0)
  			return rc;
  		if (cmd.reply_len != clen) {
  			printk(KERN_DEBUG "SMU: short read in "
  			       "smu_read_datablock, got: %d, want: %d
  ",
  			       cmd.reply_len, clen);
  			return -EIO;
  		}
  		len -= clen;
  		addr += clen;
  		dest += clen;
  	}
  	return 0;
  }
  
  static struct smu_sdbp_header *smu_create_sdb_partition(int id)
  {

  	DECLARE_COMPLETION_ONSTACK(comp);

  	struct smu_simple_cmd cmd;
  	unsigned int addr, len, tlen;
  	struct smu_sdbp_header *hdr;
  	struct property *prop;
  
  	/* First query the partition info */

  	DPRINTK("SMU: Query partition infos ... (irq=%d)
  ", smu->db_irq);

  	smu_queue_simple(&cmd, SMU_CMD_PARTITION_COMMAND, 2,
  			 smu_done_complete, &comp,
  			 SMU_CMD_PARTITION_LATEST, id);
  	wait_for_completion(&comp);

  	DPRINTK("SMU: done, status: %d, reply_len: %d
  ",
  		cmd.cmd.status, cmd.cmd.reply_len);

  
  	/* Partition doesn't exist (or other error) */
  	if (cmd.cmd.status != 0 || cmd.cmd.reply_len != 6)
  		return NULL;
  
  	/* Fetch address and length from reply */
  	addr = *((u16 *)cmd.buffer);
  	len = cmd.buffer[3] << 2;
  	/* Calucluate total length to allocate, including the 17 bytes
  	 * for "sdb-partition-XX" that we append at the end of the buffer
  	 */
  	tlen = sizeof(struct property) + len + 18;

  	prop = kzalloc(tlen, GFP_KERNEL);

  	if (prop == NULL)
  		return NULL;
  	hdr = (struct smu_sdbp_header *)(prop + 1);
  	prop->name = ((char *)prop) + tlen - 18;
  	sprintf(prop->name, "sdb-partition-%02x", id);
  	prop->length = len;

  	prop->value = hdr;

  	prop->next = NULL;
  
  	/* Read the datablock */
  	if (smu_read_datablock((u8 *)hdr, addr, len)) {
  		printk(KERN_DEBUG "SMU: datablock read failed while reading "
  		       "partition %02x !
  ", id);
  		goto failure;
  	}
  
  	/* Got it, check a few things and create the property */
  	if (hdr->id != id) {
  		printk(KERN_DEBUG "SMU: Reading partition %02x and got "
  		       "%02x !
  ", id, hdr->id);
  		goto failure;
  	}
  	if (prom_add_property(smu->of_node, prop)) {
  		printk(KERN_DEBUG "SMU: Failed creating sdb-partition-%02x "
  		       "property !
  ", id);
  		goto failure;
  	}
  
  	return hdr;
   failure:
  	kfree(prop);
  	return NULL;
  }
  
  /* Note: Only allowed to return error code in pointers (using ERR_PTR)
   * when interruptible is 1
   */

  const struct smu_sdbp_header *__smu_get_sdb_partition(int id,
  		unsigned int *size, int interruptible)

  {
  	char pname[32];

  	const struct smu_sdbp_header *part;

  
  	if (!smu)
  		return NULL;
  
  	sprintf(pname, "sdb-partition-%02x", id);

  	DPRINTK("smu_get_sdb_partition(%02x)
  ", id);

  	if (interruptible) {
  		int rc;

  		rc = mutex_lock_interruptible(&smu_part_access);

  		if (rc)
  			return ERR_PTR(rc);
  	} else

  		mutex_lock(&smu_part_access);

  	part = of_get_property(smu->of_node, pname, size);

  	if (part == NULL) {

  		DPRINTK("trying to extract from SMU ...
  ");

  		part = smu_create_sdb_partition(id);
  		if (part != NULL && size)
  			*size = part->len << 2;
  	}

  	mutex_unlock(&smu_part_access);

  	return part;
  }

  const struct smu_sdbp_header *smu_get_sdb_partition(int id, unsigned int *size)

  {
  	return __smu_get_sdb_partition(id, size, 0);

  }
  EXPORT_SYMBOL(smu_get_sdb_partition);

  
  
  /*
   * Userland driver interface
   */
  
  
  static LIST_HEAD(smu_clist);
  static DEFINE_SPINLOCK(smu_clist_lock);
  
  enum smu_file_mode {
  	smu_file_commands,
  	smu_file_events,
  	smu_file_closing
  };
  
  struct smu_private
  {
  	struct list_head	list;
  	enum smu_file_mode	mode;
  	int			busy;
  	struct smu_cmd		cmd;
  	spinlock_t		lock;
  	wait_queue_head_t	wait;
  	u8			buffer[SMU_MAX_DATA];
  };
  
  
  static int smu_open(struct inode *inode, struct file *file)
  {
  	struct smu_private *pp;
  	unsigned long flags;

  	pp = kzalloc(sizeof(struct smu_private), GFP_KERNEL);

  	if (pp == 0)
  		return -ENOMEM;

  	spin_lock_init(&pp->lock);
  	pp->mode = smu_file_commands;
  	init_waitqueue_head(&pp->wait);

  	mutex_lock(&smu_mutex);

  	spin_lock_irqsave(&smu_clist_lock, flags);
  	list_add(&pp->list, &smu_clist);
  	spin_unlock_irqrestore(&smu_clist_lock, flags);
  	file->private_data = pp;

  	mutex_unlock(&smu_mutex);

  
  	return 0;
  }
  
  
  static void smu_user_cmd_done(struct smu_cmd *cmd, void *misc)
  {
  	struct smu_private *pp = misc;
  
  	wake_up_all(&pp->wait);
  }
  
  
  static ssize_t smu_write(struct file *file, const char __user *buf,
  			 size_t count, loff_t *ppos)
  {
  	struct smu_private *pp = file->private_data;
  	unsigned long flags;
  	struct smu_user_cmd_hdr hdr;
  	int rc = 0;
  
  	if (pp->busy)
  		return -EBUSY;
  	else if (copy_from_user(&hdr, buf, sizeof(hdr)))
  		return -EFAULT;
  	else if (hdr.cmdtype == SMU_CMDTYPE_WANTS_EVENTS) {
  		pp->mode = smu_file_events;
  		return 0;

  	} else if (hdr.cmdtype == SMU_CMDTYPE_GET_PARTITION) {

  		const struct smu_sdbp_header *part;

  		part = __smu_get_sdb_partition(hdr.cmd, NULL, 1);
  		if (part == NULL)
  			return -EINVAL;
  		else if (IS_ERR(part))
  			return PTR_ERR(part);
  		return 0;

  	} else if (hdr.cmdtype != SMU_CMDTYPE_SMU)
  		return -EINVAL;
  	else if (pp->mode != smu_file_commands)
  		return -EBADFD;
  	else if (hdr.data_len > SMU_MAX_DATA)
  		return -EINVAL;
  
  	spin_lock_irqsave(&pp->lock, flags);
  	if (pp->busy) {
  		spin_unlock_irqrestore(&pp->lock, flags);
  		return -EBUSY;
  	}
  	pp->busy = 1;
  	pp->cmd.status = 1;
  	spin_unlock_irqrestore(&pp->lock, flags);
  
  	if (copy_from_user(pp->buffer, buf + sizeof(hdr), hdr.data_len)) {
  		pp->busy = 0;
  		return -EFAULT;
  	}
  
  	pp->cmd.cmd = hdr.cmd;
  	pp->cmd.data_len = hdr.data_len;
  	pp->cmd.reply_len = SMU_MAX_DATA;
  	pp->cmd.data_buf = pp->buffer;
  	pp->cmd.reply_buf = pp->buffer;
  	pp->cmd.done = smu_user_cmd_done;
  	pp->cmd.misc = pp;
  	rc = smu_queue_cmd(&pp->cmd);
  	if (rc < 0)
  		return rc;
  	return count;
  }
  
  
  static ssize_t smu_read_command(struct file *file, struct smu_private *pp,
  				char __user *buf, size_t count)
  {
  	DECLARE_WAITQUEUE(wait, current);
  	struct smu_user_reply_hdr hdr;
  	unsigned long flags;
  	int size, rc = 0;
  
  	if (!pp->busy)
  		return 0;
  	if (count < sizeof(struct smu_user_reply_hdr))
  		return -EOVERFLOW;
  	spin_lock_irqsave(&pp->lock, flags);
  	if (pp->cmd.status == 1) {

  		if (file->f_flags & O_NONBLOCK) {
  			spin_unlock_irqrestore(&pp->lock, flags);

  			return -EAGAIN;

  		}

  		add_wait_queue(&pp->wait, &wait);
  		for (;;) {
  			set_current_state(TASK_INTERRUPTIBLE);
  			rc = 0;
  			if (pp->cmd.status != 1)
  				break;
  			rc = -ERESTARTSYS;
  			if (signal_pending(current))
  				break;
  			spin_unlock_irqrestore(&pp->lock, flags);
  			schedule();
  			spin_lock_irqsave(&pp->lock, flags);
  		}
  		set_current_state(TASK_RUNNING);
  		remove_wait_queue(&pp->wait, &wait);
  	}
  	spin_unlock_irqrestore(&pp->lock, flags);
  	if (rc)
  		return rc;
  	if (pp->cmd.status != 0)
  		pp->cmd.reply_len = 0;
  	size = sizeof(hdr) + pp->cmd.reply_len;
  	if (count < size)
  		size = count;
  	rc = size;
  	hdr.status = pp->cmd.status;
  	hdr.reply_len = pp->cmd.reply_len;
  	if (copy_to_user(buf, &hdr, sizeof(hdr)))
  		return -EFAULT;
  	size -= sizeof(hdr);
  	if (size && copy_to_user(buf + sizeof(hdr), pp->buffer, size))
  		return -EFAULT;
  	pp->busy = 0;
  
  	return rc;
  }
  
  
  static ssize_t smu_read_events(struct file *file, struct smu_private *pp,
  			       char __user *buf, size_t count)
  {
  	/* Not implemented */
  	msleep_interruptible(1000);
  	return 0;
  }
  
  
  static ssize_t smu_read(struct file *file, char __user *buf,
  			size_t count, loff_t *ppos)
  {
  	struct smu_private *pp = file->private_data;
  
  	if (pp->mode == smu_file_commands)
  		return smu_read_command(file, pp, buf, count);
  	if (pp->mode == smu_file_events)
  		return smu_read_events(file, pp, buf, count);
  
  	return -EBADFD;
  }
  
  static unsigned int smu_fpoll(struct file *file, poll_table *wait)
  {
  	struct smu_private *pp = file->private_data;
  	unsigned int mask = 0;
  	unsigned long flags;
  
  	if (pp == 0)
  		return 0;
  
  	if (pp->mode == smu_file_commands) {
  		poll_wait(file, &pp->wait, wait);
  
  		spin_lock_irqsave(&pp->lock, flags);
  		if (pp->busy && pp->cmd.status != 1)
  			mask |= POLLIN;
  		spin_unlock_irqrestore(&pp->lock, flags);
  	} if (pp->mode == smu_file_events) {
  		/* Not yet implemented */
  	}
  	return mask;
  }
  
  static int smu_release(struct inode *inode, struct file *file)
  {
  	struct smu_private *pp = file->private_data;
  	unsigned long flags;
  	unsigned int busy;
  
  	if (pp == 0)
  		return 0;
  
  	file->private_data = NULL;
  
  	/* Mark file as closing to avoid races with new request */
  	spin_lock_irqsave(&pp->lock, flags);
  	pp->mode = smu_file_closing;
  	busy = pp->busy;
  
  	/* Wait for any pending request to complete */
  	if (busy && pp->cmd.status == 1) {
  		DECLARE_WAITQUEUE(wait, current);
  
  		add_wait_queue(&pp->wait, &wait);
  		for (;;) {
  			set_current_state(TASK_UNINTERRUPTIBLE);
  			if (pp->cmd.status != 1)
  				break;

  			spin_unlock_irqrestore(&pp->lock, flags);

  			schedule();
  			spin_lock_irqsave(&pp->lock, flags);

  		}
  		set_current_state(TASK_RUNNING);
  		remove_wait_queue(&pp->wait, &wait);
  	}
  	spin_unlock_irqrestore(&pp->lock, flags);
  
  	spin_lock_irqsave(&smu_clist_lock, flags);
  	list_del(&pp->list);
  	spin_unlock_irqrestore(&smu_clist_lock, flags);
  	kfree(pp);
  
  	return 0;
  }

  static const struct file_operations smu_device_fops = {

  	.llseek		= no_llseek,
  	.read		= smu_read,
  	.write		= smu_write,
  	.poll		= smu_fpoll,
  	.open		= smu_open,
  	.release	= smu_release,
  };

  static struct miscdevice pmu_device = {

  	MISC_DYNAMIC_MINOR, "smu", &smu_device_fops
  };
  
  static int smu_device_init(void)
  {
  	if (!smu)
  		return -ENODEV;
  	if (misc_register(&pmu_device) < 0)
  		printk(KERN_ERR "via-pmu: cannot register misc device.
  ");
  	return 0;
  }
  device_initcall(smu_device_init);