Author: ian Date: Sat Sep 14 19:33:36 2019 New Revision: 352338 URL: https://svnweb.freebsd.org/changeset/base/352338
Log: Create a mechanism for encoding a system errno into the IIC_Exxxxx space. Errors are communicated between the i2c controller layer and upper layers (iicbus and slave device drivers) using a set of IIC_Exxxxxx constants which effectively define a private number space separate from (and having values that conflict with) the system errno number space. Sometimes it is necessary to report a plain old system error (especially EINTR) from the controller or bus layer and have that value make it back across the syscall interface intact. I initially considered replicating a few "crucial" errno values with similar names and new numbers, e.g., IIC_EINTR, IIC_ERESTART, etc. It seemed like that had the potential to grow over time until many of the errno names were duplicated into the IIC_Exxxxx space. So instead, this defines a mechanism to "encode" an errno into the IIC_Exxxx space by setting the high bit and putting the errno into the lower-order bits; a new errno2iic() function does this. The existing iic2errno() recognizes the encoded values and extracts the original errno out of the encoded value. An interesting wrinkle occurs with the pseudo-error values such as ERESTART -- they aleady have the high bit set, and turning it off would be the wrong thing to do. Instead, iic2errno() recognizes that lots of high bits are on (i.e., it's a negative number near to zero) and just returns that value as-is. Thus, existing drivers continue to work without needing any changes, and there is now a way to return errno values from the lower layers. The first use of that is in iicbus_poll() which does mtx_sleep() with the PCATCH flag, and needs to return the errno from that up the call chain. Differential Revision: https://reviews.freebsd.org/D20975 Modified: head/sys/dev/iicbus/iiconf.c head/sys/dev/iicbus/iiconf.h Modified: head/sys/dev/iicbus/iiconf.c ============================================================================== --- head/sys/dev/iicbus/iiconf.c Sat Sep 14 19:23:46 2019 (r352337) +++ head/sys/dev/iicbus/iiconf.c Sat Sep 14 19:33:36 2019 (r352338) @@ -42,6 +42,18 @@ __FBSDID("$FreeBSD$"); #include "iicbus_if.h" /* + * Encode a system errno value into the IIC_Exxxxx space by setting the + * IIC_ERRNO marker bit, so that iic2errno() can turn it back into a plain + * system errno value later. This lets controller- and bus-layer code get + * important system errno values (such as EINTR/ERESTART) back to the caller. + */ +int +errno2iic(int errno) +{ + return ((errno == 0) ? 0 : errno | IIC_ERRNO); +} + +/* * Translate IIC_Exxxxx status values to vaguely-equivelent errno values. */ int @@ -59,7 +71,22 @@ iic2errno(int iic_status) case IIC_ENOTSUPP: return (EOPNOTSUPP); case IIC_ENOADDR: return (EADDRNOTAVAIL); case IIC_ERESOURCE: return (ENOMEM); - default: return (EIO); + default: + /* + * If the high bit is set, that means it's a system errno value + * that was encoded into the IIC_Exxxxxx space by setting the + * IIC_ERRNO marker bit. If lots of high-order bits are set, + * then it's one of the negative pseudo-errors such as ERESTART + * and we return it as-is. Otherwise it's a plain "small + * positive integer" errno, so just remove the IIC_ERRNO marker + * bit. If it's some unknown number without the high bit set, + * there isn't much we can do except call it an I/O error. + */ + if ((iic_status & IIC_ERRNO) == 0) + return (EIO); + if ((iic_status & 0xFFFF0000) != 0) + return (iic_status); + return (iic_status & ~IIC_ERRNO); } } @@ -97,7 +124,7 @@ iicbus_poll(struct iicbus_softc *sc, int how) return (IIC_EBUSBSY); } - return (error); + return (errno2iic(error)); } /* Modified: head/sys/dev/iicbus/iiconf.h ============================================================================== --- head/sys/dev/iicbus/iiconf.h Sat Sep 14 19:23:46 2019 (r352337) +++ head/sys/dev/iicbus/iiconf.h Sat Sep 14 19:33:36 2019 (r352338) @@ -96,12 +96,14 @@ #define IIC_ENOTSUPP 0x8 /* request not supported */ #define IIC_ENOADDR 0x9 /* no address assigned to the interface */ #define IIC_ERESOURCE 0xa /* resources (memory, whatever) unavailable */ +#define IIC_ERRNO __INT_MIN /* marker bit: errno is in low-order bits */ /* * Note that all iicbus functions return IIC_Exxxxx status values, * except iic2errno() (obviously) and iicbus_started() (returns bool). */ extern int iic2errno(int); +extern int errno2iic(int); extern int iicbus_request_bus(device_t, device_t, int); extern int iicbus_release_bus(device_t, device_t); extern device_t iicbus_alloc_bus(device_t); _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
