mmc: sdhci-pci: Fix BYT sd card getting stuck in runtime suspend

A host controller for a SD card may need a GPIO for card detect in order
to wake up from runtime suspend when a card is inserted.  If that GPIO is
not configured, then the host controller will not wake up.  Fix that for
the affected devices by not enabling runtime PM unless the GPIO is
successfully set up.

This affects BYT sd card host controller which had runtime PM enabled from
v3.11.  For completeness, the MFD sd card host controller is flagged also.

The original patch before rebasing (see link below) was tested on v3.11.10
and v3.12.4 although the patch applied with some offsets and fuzz.  The
original patch is here:

    http://marc.info/?l=linux-mmc&m=138676702327057Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: stable <stable@vger.kernel.org> # 3.11+
Signed-off-by: Chris Ball <chris@printf.net>

drivers/mmc/host/sdhci-pci.c

@@ -225,6 +225,7 @@ static const struct sdhci_pci_fixes sdhci_intel_mrst_hc1_hc2 = {
 static const struct sdhci_pci_fixes sdhci_intel_mfd_sd = {
 	.quirks		= SDHCI_QUIRK_NO_ENDATTR_IN_NOPDESC,
 	.allow_runtime_pm = true,
+	.own_cd_for_runtime_pm = true,
 };
 
 static const struct sdhci_pci_fixes sdhci_intel_mfd_sdio = {
@@ -289,6 +290,7 @@ static const struct sdhci_pci_fixes sdhci_intel_byt_sdio = {
 static const struct sdhci_pci_fixes sdhci_intel_byt_sd = {
 	.quirks2	= SDHCI_QUIRK2_CARD_ON_NEEDS_BUS_ON,
 	.allow_runtime_pm = true,
+	.own_cd_for_runtime_pm = true,
 };
 
 /* Define Host controllers for Intel Merrifield platform */
@@ -1371,6 +1373,14 @@ static struct sdhci_pci_slot *sdhci_pci_probe_slot(
 
 	sdhci_pci_add_own_cd(slot);
 
+	/*
+	 * Check if the chip needs a separate GPIO for card detect to wake up
+	 * from runtime suspend.  If it is not there, don't allow runtime PM.
+	 * Note sdhci_pci_add_own_cd() sets slot->cd_gpio to -EINVAL on failure.
+	 */
+	if (chip->fixes->own_cd_for_runtime_pm && !gpio_is_valid(slot->cd_gpio))
+		chip->allow_runtime_pm = false;
+
 	return slot;
 
 remove:

drivers/mmc/host/sdhci-pci.h

@@ -39,6 +39,7 @@ struct sdhci_pci_fixes {
 	unsigned int		quirks;
 	unsigned int		quirks2;
 	bool			allow_runtime_pm;
+	bool			own_cd_for_runtime_pm;
 
 	int			(*probe) (struct sdhci_pci_chip *);