[PATCH v2 2/4] mmc: dt: Allow to specify that no write protect signal is present

Lars-Peter Clausen
2015-05-06T18:31:20Z

Allow to specify in the device-tree that no physical write-protect signal
is connected to a particular instance of a MMC controller. Setting the
property will cause the core will assume that the SD card is always
read-write.

The name for the new property is 'disable-wp' and was chosen based on the
property with the same function from the Synopsys designware mobile storage
host controller DT bindings specification.

Signed-off-by: Lars-Peter Clausen <lars-Qo5EllUWu/uELgA04lAiVw@public.gmane.org>
Cc: Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: Pawel Moll <pawel.moll-5wv7dgnIgG8@public.gmane.org>
Cc: Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>
Cc: Ian Campbell <ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org>
Cc: Kumar Gala <galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
---
Documentation/devicetree/bindings/mmc/mmc.txt | 5 +++++
drivers/mmc/core/host.c | 3 +++
2 files changed, 8 insertions(+)

diff --git a/Documentation/devicetree/bindings/mmc/mmc.txt b/Documentation/devicetree/bindings/mmc/mmc.txt
index 438899e..0384fc3 100644
--- a/Documentation/devicetree/bindings/mmc/mmc.txt
+++ b/Documentation/devicetree/bindings/mmc/mmc.txt
@@ -21,6 +21,11 @@ Optional properties:
below for the case, when a GPIO is used for the CD line
- wp-inverted: when present, polarity on the WP line is inverted. See the note
below for the case, when a GPIO is used for the WP line
+- disable-wp: When set no physical WP line is present. This property should
+ only be specified when the controller has a dedicated write-protect
+ detection logic. If a GPIO is always used for the write-protect detection
+ logic it is sufficient to not specify wp-gpios property in the absence of a WP
+ line.
- max-frequency: maximum operating clock frequency
- no-1-8-v: when present, denotes that 1.8v card voltage is not supported on
this system, even if the controller claims it is.
diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 8be0df7..1eabdd0 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -400,6 +400,9 @@ int mmc_of_parse(struct mmc_host *host)
else if (ret != -ENOENT)
return ret;

+ if (of_property_read_bool(np, "disable-wp"))
+ host->caps2 |= MMC_CAP2_NO_WRITE_PROTECT;
+
/* See the comment on CD inversion above */
if (ro_cap_invert ^ ro_gpio_invert)
host->caps2 |= MMC_CAP2_RO_ACTIVE_HIGH;
--
1.8.0

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