mmc_fdt: handle broken-cd property

The documented properties [1] for card-detection are one of:
 - cd-gpios
 - non-removable
 - broken-cd

In cd_setup() we handle the first two, but not the latter, resulting in
a silently undetected card on an affected system.

To work around this, force cd_disabled when broken-cd is specified, so
that the card detect helper function gets to run. A more complete
solution would implement some kind of polling mechanism to detect the
card's presence or removal.

Some variants of the Allwinner D1, such as the Lichee Rv, specify this
property in the mmc0 device node.

[1] sys/contrib/device-tree/Bindings/mmc/mmc-controller.yaml

Reported by:	Haowu Ge <gehaowu@bitmoe.com>
Tested by:	Haowu Ge <gehaowu@bitmoe.com>
Reviewed by:	imp, manu, mmel
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D53546

1 files changed, 11 insertions, 0 deletions

diff --git a/sys/dev/mmc/mmc_fdt_helpers.c b/sys/dev/mmc/mmc_fdt_helpers.c
index aed85dab55f4..980785464a00 100644
--- a/sys/dev/mmc/mmc_fdt_helpers.c
+++ b/sys/dev/mmc/mmc_fdt_helpers.c
@@ -160,6 +160,17 @@ cd_setup(struct mmc_helper *helper, phandle_t node)
 	}
 
 	/*
+	 * If the device has no card-detection, treat it as non-removable.
+	 * This could be improved by polling for detection.
+	 */
+	if (helper->props & MMC_PROP_BROKEN_CD) {
+		helper->cd_disabled = true;
+		if (bootverbose)
+			device_printf(dev, "Broken card-detect\n");
+		return;
+	}
+
+	/*
 	 * If there is no cd-gpios property, then presumably the hardware
 	 * PRESENT_STATE register and interrupts will reflect card state
 	 * properly, and there's nothing more for us to do.  Our get_present()