mmc: change .get_ro() callback semantics
Now get_ro() callback must return 0/1 values for its logical states, and
negative errno values in case of error. If particular host instance doesn't
support RO/WP switch, it should return -ENOSYS.
This patch changes some hosts in two ways:
1. Now functions should be smart to not return negative values in
"RO asserted" case (particularly gpio_ calls could return negative
values for the outermost GPIOs).
Also, board code usually passes get_ro() callbacks that directly return
gpioreg & bit result, so at91_mci, imxmmc, pxamci and mmc_spi's get_ro()
handlers need take special care when returning platform's values to the
mmc core.
2. In case of host instance didn't implement get_ro() callback, it should
really return -ENOSYS and let the mmc core decide what to do about it
(mmc core thinks the same way as the hosts, so it isn't functional
change).
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 6188e19..753b723 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -58,6 +58,18 @@
*
* Also note that these functions might sleep, so don't call them
* in the atomic contexts!
+ *
+ * Return values for the get_ro callback should be:
+ * 0 for a read/write card
+ * 1 for a read-only card
+ * -ENOSYS when not supported (equal to NULL callback)
+ * or a negative errno value when something bad happened
+ *
+ * Return values for the get_ro callback should be:
+ * 0 for a absent card
+ * 1 for a present card
+ * -ENOSYS when not supported (equal to NULL callback)
+ * or a negative errno value when something bad happened
*/
void (*set_ios)(struct mmc_host *host, struct mmc_ios *ios);
int (*get_ro)(struct mmc_host *host);