[PATCH] ppc64: SMU driver update & i2c support

The SMU is the "system controller" chip used by Apple recent G5 machines
including the iMac G5.  It drives things like fans, i2c busses, real time
clock, etc...

The current kernel contains a very crude driver that doesn't do much more
than reading the real time clock synchronously.  This is a completely
rewritten driver that provides interrupt based command queuing, a userland
interface, and an i2c/smbus driver for accessing the devices hanging off
the SMU i2c busses like temperature sensors.  This driver is a basic block
for upcoming work on thermal control for those machines, among others.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 891 insertions, 139 deletions

diff --git a/drivers/macintosh/smu.c b/drivers/macintosh/smu.c
index fb535737d17d..a85ac18dd21d 100644
--- a/drivers/macintosh/smu.c
+++ b/drivers/macintosh/smu.c
@@ -8,21 +8,15 @@
  */
 
 /*
- * For now, this driver includes:
- * - RTC get & set
- * - reboot & shutdown commands
- * all synchronous with IRQ disabled (ugh)
- *
  * TODO:
- *   rework in a way the PMU driver works, that is asynchronous
- *   with a queue of commands. I'll do that as soon as I have an
- *   SMU based machine at hand. Some more cleanup is needed too,
- *   like maybe fitting it into a platform device, etc...
- *   Also check what's up with cache coherency, and if we really
- *   can't do better than flushing the cache, maybe build a table
- *   of command len/reply len like the PMU driver to only flush
- *   what is actually necessary.
- *   --BenH.
+ *  - maybe add timeout to commands ?
+ *  - blocking version of time functions
+ *  - polling version of i2c commands (including timer that works with
+ *    interrutps 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/config.h>
@@ -36,6 +30,11 @@
 #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/sysdev.h>
+#include <linux/poll.h>
 
 #include <asm/byteorder.h>
 #include <asm/io.h>
@@ -45,8 +44,13 @@
 #include <asm/smu.h>
 #include <asm/sections.h>
 #include <asm/abs_addr.h>
+#include <asm/uaccess.h>
+#include <asm/of_device.h>
+
+#define VERSION "0.6"
+#define AUTHOR  "(c) 2005 Benjamin Herrenschmidt, IBM Corp."
 
-#define DEBUG_SMU 1
+#undef DEBUG_SMU
 
 #ifdef DEBUG_SMU
 #define DPRINTK(fmt, args...) do { printk(KERN_DEBUG fmt , ##args); } while (0)
@@ -57,20 +61,30 @@
 /*
  * 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[0x0FFE];
+	u8 data[SMU_MAX_DATA];
 };
 
 struct smu_device {
 	spinlock_t		lock;
 	struct device_node	*of_node;
-	int			db_ack;		/* doorbell ack GPIO */
-	int			db_req;		/* doorbell req GPIO */
+	struct of_device	*of_dev;
+	int			doorbell;	/* doorbell gpio */
 	u32 __iomem		*db_buf;	/* doorbell buffer */
+	int			db_irq;
+	int			msg;
+	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 */
+	struct list_head	cmd_i2c_list;
+	struct smu_i2c_cmd	*cmd_i2c_cur;	/* pending i2c command */
+	struct timer_list	i2c_timer;
 };
 
 /*
@@ -79,113 +93,243 @@ struct smu_device {
  */
 static struct smu_device	*smu;
 
+
 /*
- * SMU low level communication stuff
+ * SMU driver low level stuff
  */
-static inline int smu_cmd_stat(struct smu_cmd_buf *cmd_buf, u8 cmd_ack)
-{
-	rmb();
-	return cmd_buf->cmd == cmd_ack && cmd_buf->length != 0;
-}
 
-static inline u8 smu_save_ack_cmd(struct smu_cmd_buf *cmd_buf)
+static void smu_start_cmd(void)
 {
-	return (~cmd_buf->cmd) & 0xff;
-}
+	unsigned long faddr, fend;
+	struct smu_cmd *cmd;
 
-static void smu_send_cmd(struct smu_device *dev)
-{
-	/* SMU command buf is currently cacheable, we need a physical
-	 * address. This isn't exactly a DMA mapping here, I suspect
+	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\n", cmd->cmd,
+		cmd->data_len);
+	DPRINTK("SMU: data buffer: %02x %02x %02x %02x ...\n",
+		((u8 *)cmd->data_buf)[0], ((u8 *)cmd->data_buf)[1],
+		((u8 *)cmd->data_buf)[2], ((u8 *)cmd->data_buf)[3]);
+
+	/* 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);
+
+	/* 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(dev->cmd_buf_abs, dev->db_buf);
+	writel(smu->cmd_buf_abs, smu->db_buf);
 
 	/* Ring the SMU doorbell */
-	pmac_do_feature_call(PMAC_FTR_WRITE_GPIO, NULL, dev->db_req, 4);
-	pmac_do_feature_call(PMAC_FTR_READ_GPIO, NULL, dev->db_req, 4);
+	pmac_do_feature_call(PMAC_FTR_WRITE_GPIO, NULL, smu->doorbell, 4);
 }
 
-static int smu_cmd_done(struct smu_device *dev)
+
+static irqreturn_t smu_db_intr(int irq, void *arg, struct pt_regs *regs)
 {
-	unsigned long wait = 0;
-	int gpio;
+	unsigned long flags;
+	struct smu_cmd *cmd;
+	void (*done)(struct smu_cmd *cmd, void *misc) = NULL;
+	void *misc = NULL;
+	u8 gpio;
+	int rc = 0;
 
-	/* Check the SMU doorbell */
-	do  {
-		gpio = pmac_do_feature_call(PMAC_FTR_READ_GPIO,
-					    NULL, dev->db_ack);
-		if ((gpio & 7) == 7)
-			return 0;
-		udelay(100);
-	} while(++wait < 10000);
+	/* SMU completed the command, well, we hope, let's make sure
+	 * of it
+	 */
+	spin_lock_irqsave(&smu->lock, flags);
 
-	printk(KERN_ERR "SMU timeout !\n");
-	return -ENXIO;
+	gpio = pmac_do_feature_call(PMAC_FTR_READ_GPIO, NULL, smu->doorbell);
+	if ((gpio & 7) != 7)
+		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 lenght (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\n",
+				ack, smu->cmd_buf->cmd);
+			rc = -EIO;
+		}
+		reply_len = rc == 0 ? smu->cmd_buf->length : 0;
+		DPRINTK("SMU: reply len: %d\n", reply_len);
+		if (reply_len > cmd->reply_len) {
+			printk(KERN_WARNING "SMU: reply buffer too small,"
+			       "got %d bytes for a %d bytes buffer\n",
+			       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;
+ 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 int smu_do_cmd(struct smu_device *dev)
+
+static irqreturn_t smu_msg_intr(int irq, void *arg, struct pt_regs *regs)
 {
-	int rc;
-	u8 cmd_ack;
+	/* 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 !\n");
 
-	DPRINTK("SMU do_cmd %02x len=%d %02x\n",
-		dev->cmd_buf->cmd, dev->cmd_buf->length,
-		dev->cmd_buf->data[0]);
+	/* It's an edge interrupt, nothing to do */
+	return IRQ_HANDLED;
+}
 
-	cmd_ack = smu_save_ack_cmd(dev->cmd_buf);
 
-	/* Clear cmd_buf cache lines */
-	flush_inval_dcache_range((unsigned long)dev->cmd_buf,
-				 ((unsigned long)dev->cmd_buf) +
-				 sizeof(struct smu_cmd_buf));
-	smu_send_cmd(dev);
-	rc = smu_cmd_done(dev);
-	if (rc == 0)
-		rc = smu_cmd_stat(dev->cmd_buf, cmd_ack) ? 0 : -1;
+/*
+ * Queued command management.
+ *
+ */
 
-	DPRINTK("SMU do_cmd %02x len=%d %02x => %d (%02x)\n",
-		dev->cmd_buf->cmd, dev->cmd_buf->length,
-		dev->cmd_buf->data[0], rc, cmd_ack);
+int smu_queue_cmd(struct smu_cmd *cmd)
+{
+	unsigned long flags;
 
-	return rc;
+	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);
+
+	return 0;
 }
+EXPORT_SYMBOL(smu_queue_cmd);
 
-/* RTC low level commands */
-static inline int bcd2hex (int n)
+
+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, ...)
 {
-	return (((n & 0xf0) >> 4) * 10) + (n & 0xf);
+	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);
 
-static inline int hex2bcd (int n)
+
+void smu_poll(void)
 {
-	return ((n / 10) << 4) + (n % 10);
+	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, NULL);
 }
+EXPORT_SYMBOL(smu_poll);
+
 
-#if 0
-static inline void smu_fill_set_pwrup_timer_cmd(struct smu_cmd_buf *cmd_buf)
+void smu_done_complete(struct smu_cmd *cmd, void *misc)
 {
-	cmd_buf->cmd = 0x8e;
-	cmd_buf->length = 8;
-	cmd_buf->data[0] = 0x00;
-	memset(cmd_buf->data + 1, 0, 7);
+	struct completion *comp = misc;
+
+	complete(comp);
 }
+EXPORT_SYMBOL(smu_done_complete);
+
 
-static inline void smu_fill_get_pwrup_timer_cmd(struct smu_cmd_buf *cmd_buf)
+void smu_spinwait_cmd(struct smu_cmd *cmd)
 {
-	cmd_buf->cmd = 0x8e;
-	cmd_buf->length = 1;
-	cmd_buf->data[0] = 0x01;
+	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 void smu_fill_dis_pwrup_timer_cmd(struct smu_cmd_buf *cmd_buf)
+
+static inline int hex2bcd (int n)
 {
-	cmd_buf->cmd = 0x8e;
-	cmd_buf->length = 1;
-	cmd_buf->data[0] = 0x02;
+	return ((n / 10) << 4) + (n % 10);
 }
-#endif
+
 
 static inline void smu_fill_set_rtc_cmd(struct smu_cmd_buf *cmd_buf,
 					struct rtc_time *time)
@@ -202,100 +346,96 @@ static inline void smu_fill_set_rtc_cmd(struct smu_cmd_buf *cmd_buf,
 	cmd_buf->data[7] = hex2bcd(time->tm_year - 100);
 }
 
-static inline void smu_fill_get_rtc_cmd(struct smu_cmd_buf *cmd_buf)
-{
-	cmd_buf->cmd = 0x8e;
-	cmd_buf->length = 1;
-	cmd_buf->data[0] = 0x81;
-}
 
-static void smu_parse_get_rtc_reply(struct smu_cmd_buf *cmd_buf,
-				    struct rtc_time *time)
+int smu_get_rtc_time(struct rtc_time *time, int spinwait)
 {
-	time->tm_sec = bcd2hex(cmd_buf->data[0]);
-	time->tm_min = bcd2hex(cmd_buf->data[1]);
-	time->tm_hour = bcd2hex(cmd_buf->data[2]);
-	time->tm_wday = bcd2hex(cmd_buf->data[3]);
-	time->tm_mday = bcd2hex(cmd_buf->data[4]);
-	time->tm_mon = bcd2hex(cmd_buf->data[5]) - 1;
-	time->tm_year = bcd2hex(cmd_buf->data[6]) + 100;
-}
-
-int smu_get_rtc_time(struct rtc_time *time)
-{
-	unsigned long flags;
+	struct smu_simple_cmd cmd;
 	int rc;
 
 	if (smu == NULL)
 		return -ENODEV;
 
 	memset(time, 0, sizeof(struct rtc_time));
-	spin_lock_irqsave(&smu->lock, flags);
-	smu_fill_get_rtc_cmd(smu->cmd_buf);
-	rc = smu_do_cmd(smu);
-	if (rc == 0)
-		smu_parse_get_rtc_reply(smu->cmd_buf, time);
-	spin_unlock_irqrestore(&smu->lock, flags);
+	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);
 
-	return rc;
+	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 smu_set_rtc_time(struct rtc_time *time, int spinwait)
 {
-	unsigned long flags;
+	struct smu_simple_cmd cmd;
 	int rc;
 
 	if (smu == NULL)
 		return -ENODEV;
 
-	spin_lock_irqsave(&smu->lock, flags);
-	smu_fill_set_rtc_cmd(smu->cmd_buf, time);
-	rc = smu_do_cmd(smu);
-	spin_unlock_irqrestore(&smu->lock, flags);
+	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 rc;
+	return 0;
 }
 
+
 void smu_shutdown(void)
 {
-	const unsigned char *command = "SHUTDOWN";
-	unsigned long flags;
+	struct smu_simple_cmd cmd;
 
 	if (smu == NULL)
 		return;
 
-	spin_lock_irqsave(&smu->lock, flags);
-	smu->cmd_buf->cmd = 0xaa;
-	smu->cmd_buf->length = strlen(command);
-	strcpy(smu->cmd_buf->data, command);
-	smu_do_cmd(smu);
+	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 (;;)
 		;
-	spin_unlock_irqrestore(&smu->lock, flags);
 }
 
+
 void smu_restart(void)
 {
-	const unsigned char *command = "RESTART";
-	unsigned long flags;
+	struct smu_simple_cmd cmd;
 
 	if (smu == NULL)
 		return;
 
-	spin_lock_irqsave(&smu->lock, flags);
-	smu->cmd_buf->cmd = 0xaa;
-	smu->cmd_buf->length = strlen(command);
-	strcpy(smu->cmd_buf->data, command);
-	smu_do_cmd(smu);
+	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 (;;)
 		;
-	spin_unlock_irqrestore(&smu->lock, flags);
 }
 
+
 int smu_present(void)
 {
 	return smu != NULL;
 }
+EXPORT_SYMBOL(smu_present);
 
 
 int smu_init (void)
@@ -307,6 +447,8 @@ int smu_init (void)
         if (np == NULL)
 		return -ENODEV;
 
+	printk(KERN_INFO "SMU driver %s %s\n", VERSION, AUTHOR);
+
 	if (smu_cmdbuf_abs == 0) {
 		printk(KERN_ERR "SMU: Command buffer not allocated !\n");
 		return -EINVAL;
@@ -318,7 +460,13 @@ int smu_init (void)
 	memset(smu, 0, sizeof(*smu));
 
 	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;
+	init_timer(&smu->i2c_timer);
+
 	/* smu_cmdbuf_abs is in the low 2G of RAM, can be converted to a
 	 * 32 bits value safely
 	 */
@@ -331,8 +479,8 @@ int smu_init (void)
 		goto fail;
 	}
 	data = (u32 *)get_property(np, "reg", NULL);
-	of_node_put(np);
 	if (data == NULL) {
+		of_node_put(np);
 		printk(KERN_ERR "SMU: Can't find doorbell GPIO address !\n");
 		goto fail;
 	}
@@ -341,8 +489,31 @@ int smu_init (void)
 	 * and ack. GPIOs are at 0x50, best would be to find that out
 	 * in the device-tree though.
 	 */
-	smu->db_req = 0x50 + *data;
-	smu->db_ack = 0x50 + *data;
+	smu->doorbell = *data;
+	if (smu->doorbell < 0x50)
+		smu->doorbell += 0x50;
+	if (np->n_intrs > 0)
+		smu->db_irq = np->intrs[0].line;
+
+	of_node_put(np);
+
+	/* Now look for the smu-interrupt GPIO */
+	do {
+		np = of_find_node_by_name(NULL, "smu-interrupt");
+		if (np == NULL)
+			break;
+		data = (u32 *)get_property(np, "reg", NULL);
+		if (data == NULL) {
+			of_node_put(np);
+			break;
+		}
+		smu->msg = *data;
+		if (smu->msg < 0x50)
+			smu->msg += 0x50;
+		if (np->n_intrs > 0)
+			smu->msg_irq = np->intrs[0].line;
+		of_node_put(np);
+	} 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
@@ -362,3 +533,584 @@ int smu_init (void)
 	return -ENXIO;
 
 }
+
+
+static int smu_late_init(void)
+{
+	if (!smu)
+		return 0;
+
+	/*
+	 * Try to request the interrupts
+	 */
+
+	if (smu->db_irq != NO_IRQ) {
+		if (request_irq(smu->db_irq, smu_db_intr,
+				SA_SHIRQ, "SMU doorbell", smu) < 0) {
+			printk(KERN_WARNING "SMU: can't "
+			       "request interrupt %d\n",
+			       smu->db_irq);
+			smu->db_irq = NO_IRQ;
+		}
+	}
+
+	if (smu->msg_irq != NO_IRQ) {
+		if (request_irq(smu->msg_irq, smu_msg_intr,
+				SA_SHIRQ, "SMU message", smu) < 0) {
+			printk(KERN_WARNING "SMU: can't "
+			       "request interrupt %d\n",
+			       smu->msg_irq);
+			smu->msg_irq = NO_IRQ;
+		}
+	}
+
+	return 0;
+}
+arch_initcall(smu_late_init);
+
+/*
+ * sysfs visibility
+ */
+
+static void smu_expose_childs(void *unused)
+{
+	struct device_node *np;
+
+	for (np = NULL; (np = of_get_next_child(smu->of_node, np)) != NULL;) {
+		if (device_is_compatible(np, "smu-i2c")) {
+			char name[32];
+			u32 *reg = (u32 *)get_property(np, "reg", NULL);
+
+			if (reg == NULL)
+				continue;
+			sprintf(name, "smu-i2c-%02x", *reg);
+			of_platform_device_create(np, name, &smu->of_dev->dev);
+		}
+	}
+
+}
+
+static DECLARE_WORK(smu_expose_childs_work, smu_expose_childs, NULL);
+
+static int smu_platform_probe(struct of_device* dev,
+			      const struct of_device_id *match)
+{
+	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 struct of_device_id smu_platform_match[] =
+{
+	{
+		.type		= "smu",
+	},
+	{},
+};
+
+static struct of_platform_driver smu_of_platform_driver =
+{
+	.name 		= "smu",
+	.match_table	= smu_platform_match,
+	.probe		= smu_platform_probe,
+};
+
+static int __init smu_init_sysfs(void)
+{
+	int rc;
+
+	/*
+	 * Due to sysfs bogosity, a sysdev is not a real device, so
+	 * we should in fact create both if we want sysdev semantics
+	 * for power management.
+	 * 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
+	 */
+	rc = of_register_driver(&smu_of_platform_driver);
+	return 0;
+}
+
+device_initcall(smu_init_sysfs);
+
+struct of_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\n", !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 = (struct smu_i2c_cmd *)data;
+
+	DPRINTK("SMU: i2c failure, requeuing...\n");
+
+	/* requeue command simply by resetting reply_len */
+	cmd->pdata[0] = 0xff;
+	cmd->scmd.reply_len = 0x10;
+	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\n",
+		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...\n");
+		smu->i2c_timer.function = smu_i2c_retry;
+		smu->i2c_timer.data = (unsigned long)cmd;
+		smu->i2c_timer.expires = jiffies + msecs_to_jiffies(5);
+		add_timer(&smu->i2c_timer);
+		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\n");
+
+	/* Ok, initial command complete, now poll status */
+	scmd->reply_buf = cmd->pdata;
+	scmd->reply_len = 0x10;
+	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 = 0x10;
+	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\n");
+	DPRINTK("SMU:   %s, len=%d bus=%x addr=%x sub0=%x type=%x\n",
+		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;
+}
+
+
+
+/*
+ * 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 = kmalloc(sizeof(struct smu_private), GFP_KERNEL);
+	if (pp == 0)
+		return -ENOMEM;
+	memset(pp, 0, sizeof(struct smu_private));
+	spin_lock_init(&pp->lock);
+	pp->mode = smu_file_commands;
+	init_waitqueue_head(&pp->wait);
+
+	spin_lock_irqsave(&smu_clist_lock, flags);
+	list_add(&pp->list, &smu_clist);
+	spin_unlock_irqrestore(&smu_clist_lock, flags);
+	file->private_data = pp;
+
+	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_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)
+			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_lock_irqsave(&pp->lock, flags);
+			schedule();
+			spin_unlock_irqrestore(&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 struct file_operations smu_device_fops __pmacdata = {
+	.llseek		= no_llseek,
+	.read		= smu_read,
+	.write		= smu_write,
+	.poll		= smu_fpoll,
+	.open		= smu_open,
+	.release	= smu_release,
+};
+
+static struct miscdevice pmu_device __pmacdata = {
+	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.\n");
+	return 0;
+}
+device_initcall(smu_device_init);