mmc: tmio: support IP-builtin card detection logic

A card detect GPIO is set up only for platforms with "cd-gpios"
DT property or TMIO_MMC_USE_GPIO_CD flag.  However, the driver
core always uses mmc_gpio_get_cd, which just fails with -ENOSYS
if ctx->cd_gpio is unset.

The bit 5 of the status register provides the current signal level
of the CD line.  Allow to use it if the GPIO is unused.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

drivers/mmc/host/tmio_mmc_core.c

@@ -1066,6 +1066,14 @@ static int tmio_mmc_get_ro(struct mmc_host *mmc)
 		 TMIO_STAT_WRPROTECT);
 }
 
+static int tmio_mmc_get_cd(struct mmc_host *mmc)
+{
+	struct tmio_mmc_host *host = mmc_priv(mmc);
+
+	return !!(sd_ctrl_read16_and_16_as_32(host, CTL_STATUS) &
+		  TMIO_STAT_SIGSTATE);
+}
+
 static int tmio_multi_io_quirk(struct mmc_card *card,
 			       unsigned int direction, int blk_size)
 {
@@ -1081,7 +1089,7 @@ static const struct mmc_host_ops tmio_mmc_ops = {
 	.request	= tmio_mmc_request,
 	.set_ios	= tmio_mmc_set_ios,
 	.get_ro         = tmio_mmc_get_ro,
-	.get_cd		= mmc_gpio_get_cd,
+	.get_cd		= tmio_mmc_get_cd,
 	.enable_sdio_irq = tmio_mmc_enable_sdio_irq,
 	.multi_io_quirk	= tmio_multi_io_quirk,
 	.hw_reset	= tmio_mmc_hw_reset,
@@ -1234,6 +1242,9 @@ int tmio_mmc_host_probe(struct tmio_mmc_host *_host)
 	if (mmc_can_gpio_ro(mmc))
 		_host->ops.get_ro = mmc_gpio_get_ro;
 
+	if (mmc_can_gpio_cd(mmc))
+		_host->ops.get_cd = mmc_gpio_get_cd;
+
 	_host->native_hotplug = !(mmc_can_gpio_cd(mmc) ||
 				  mmc->caps & MMC_CAP_NEEDS_POLL ||
 				  !mmc_card_is_removable(mmc));