Minor overhaul of SMBus support:

- Change smbus_callback() to pass a void * rather than caddr_t.
- Change smbus_bread() to pass a pointer to the count and have it be an
  in/out parameter.  The input is the size of the buffer (same as before),
  but on return it will contain the actual amount of data read back from
  the bus.  Note that this value may be larger than the input value.  It
  is up to the caller to treat this as an error if desired.
- Change the SMB_BREAD ioctl to write out the updated struct smbcmd which
  will contain the actual number of bytes read in the 'count' field.  To
  preserve the previous ABI, the old ioctl value is mapped to SMB_OLD_BREAD
  which doesn't copy the updated smbcmd back out to userland.  I doubt anyone
  actually used the old BREAD anyway as it was rediculous to do a bulk-read
  but not tell the using program how much data was actually read.
- Make the smbus driver and devclass public in the smbus module and
  push all the DRIVER_MODULE()'s for attaching the smbus driver to
  various foosmb drivers out into the foosmb modules.  This makes all
  the foosmb logic centralized and allows new foosmb modules to be
  self-contained w/o having to hack smbus.c everytime a new smbus driver
  is added.
- Add a new SMB_EINVAL error bit and use it in place of EINVAL to return
  an error for bad arguments (such as invalid counts for bread and bwrite).
- Map SMB bus error bits to EIO in smbus_error().
- Make the smbus driver call bus_generic_probe() and require child drivers
  such as smb(4) to create device_t's via identify routines.  Previously,
  smbus just created one anonymous device during attach, and if you had
  multiple drivers that could attach it was just random chance as to which
  driver got to probe for the sole device_t first.
- Add a mutex to the smbus(4) softc and use it in place of dummy splhigh()
  to protect the 'owner' field and perform necessary synchronization for
  smbus_request_bus() and smbus_release_bus().
- Change the bread() and bwrite() methods of alpm(4), amdpm(4), and
  viapm(4) to only perform a single transaction and not try to use a
  loop of multiple transactions for a large request.  The framing and
  commands to use for a large transaction depend on the upper-layer
  protocol (such as SSIF for IPMI over SMBus) from what I can tell, and the
  smb(4) driver never allowed bulk read/writes of more than 32-bytes
  anyway.  The other smb drivers only performed single transactions.
- Fix buffer overflows in the bread() methods of ichsmb(4), alpm(4),
  amdpm(4), amdsmb(4), intpm(4), and nfsmb(4).
- Use SMB_xxx errors in viapm(4).
- Destroy ichsmb(4)'s mutex after bus_generic_detach() to avoid problems
  from child devices making smb upcalls that would use the mutex during
  their detach methods.

MFC after:	1 week
Reviewed by:	jmg (mostly)

1 files changed, 17 insertions, 4 deletions

diff --git a/sys/dev/smbus/smb.c b/sys/dev/smbus/smb.c
index ca4fbe6..e5944bd 100644
--- a/sys/dev/smbus/smb.c
+++ b/sys/dev/smbus/smb.c
@@ -55,6 +55,7 @@ struct smb_softc {
 #define IIC_DEVICE(unit) \
 	(devclass_get_device(smb_devclass, (unit)))
 
+static void smb_identify(driver_t *driver, device_t parent);
 static int smb_probe(device_t);
 static int smb_attach(device_t);
 static int smb_detach(device_t);
@@ -63,6 +64,7 @@ static devclass_t smb_devclass;
 
 static device_method_t smb_methods[] = {
 	/* device interface */
+	DEVMETHOD(device_identify,	smb_identify),
 	DEVMETHOD(device_probe,		smb_probe),
 	DEVMETHOD(device_attach,	smb_attach),
 	DEVMETHOD(device_detach,	smb_detach),
@@ -92,6 +94,14 @@ static struct cdevsw smb_cdevsw = {
 	.d_name =	"smb",
 };
 
+static void
+smb_identify(driver_t *driver, device_t parent)
+{
+
+	if (device_find_child(parent, "smb", -1) == NULL)
+		BUS_ADD_CHILD(parent, 0, "smb", -1);
+}
+
 static int
 smb_probe(device_t dev)
 {
@@ -171,6 +181,7 @@ smbioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags, struct thread *t
 	device_t smbdev = IIC_DEVICE(minor(dev));
 	int error;
 	short w;
+	u_char count;
 	char c;
 
 	if (sc == NULL)
@@ -259,15 +270,17 @@ smbioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags, struct thread *t
 		}
 		break;
 
+	case SMB_OLD_BREAD:
 	case SMB_BREAD:
 		if (s->count && s->data.byte_ptr) {
-			if (s->count > SMB_MAXBLOCKSIZE)
-				s->count = SMB_MAXBLOCKSIZE;
+			count = min(s->count, SMB_MAXBLOCKSIZE);
 			error = smbus_error(smbus_bread(parent, s->slave,
-						s->cmd, s->count, buf));
+						s->cmd, &count, buf));
 			if (error)
 				break;
-			error = copyout(buf, s->data.byte_ptr, s->count);
+			error = copyout(buf, s->data.byte_ptr,
+			    min(count, s->count));
+			s->count = count;
 		}
 		break;