mmc: sdhci: Allow platform controlled voltage switching

If vendor platform drivers are controlling whole logic of voltage
switching, then sdhci driver no need control vqmmc regulator.
So skip enabling/disable vqmmc from SDHC driver.

Signed-off-by: Vijay Viswanath <vviswana@codeaurora.org>
Signed-off-by: Veerabhadrarao Badiganti <vbadigan@codeaurora.org>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/1592919288-1020-2-git-send-email-vbadigan@codeaurora.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci.c

@@ -4105,6 +4105,7 @@ int sdhci_setup_host(struct sdhci_host *host)
 	unsigned int override_timeout_clk;
 	u32 max_clk;
 	int ret;
+	bool enable_vqmmc = false;
 
 	WARN_ON(host == NULL);
 	if (host == NULL)
@@ -4118,9 +4119,12 @@ int sdhci_setup_host(struct sdhci_host *host)
 	 * the host can take the appropriate action if regulators are not
 	 * available.
 	 */
-	ret = mmc_regulator_get_supply(mmc);
-	if (ret)
-		return ret;
+	if (!mmc->supply.vqmmc) {
+		ret = mmc_regulator_get_supply(mmc);
+		if (ret)
+			return ret;
+		enable_vqmmc  = true;
+	}
 
 	DBG("Version:   0x%08x | Present:  0x%08x\n",
 	    sdhci_readw(host, SDHCI_HOST_VERSION),
@@ -4377,7 +4381,15 @@ int sdhci_setup_host(struct sdhci_host *host)
 		mmc->caps |= MMC_CAP_NEEDS_POLL;
 
 	if (!IS_ERR(mmc->supply.vqmmc)) {
-		ret = regulator_enable(mmc->supply.vqmmc);
+		if (enable_vqmmc) {
+			ret = regulator_enable(mmc->supply.vqmmc);
+			if (ret) {
+				pr_warn("%s: Failed to enable vqmmc regulator: %d\n",
+					mmc_hostname(mmc), ret);
+				mmc->supply.vqmmc = ERR_PTR(-EINVAL);
+			}
+			host->sdhci_core_to_disable_vqmmc = !ret;
+		}
 
 		/* If vqmmc provides no 1.8V signalling, then there's no UHS */
 		if (!regulator_is_supported_voltage(mmc->supply.vqmmc, 1700000,
@@ -4390,12 +4402,6 @@ int sdhci_setup_host(struct sdhci_host *host)
 		if (!regulator_is_supported_voltage(mmc->supply.vqmmc, 2700000,
 						    3600000))
 			host->flags &= ~SDHCI_SIGNALING_330;
-
-		if (ret) {
-			pr_warn("%s: Failed to enable vqmmc regulator: %d\n",
-				mmc_hostname(mmc), ret);
-			mmc->supply.vqmmc = ERR_PTR(-EINVAL);
-		}
 	}
 
 	if (host->quirks2 & SDHCI_QUIRK2_NO_1_8_V) {
@@ -4626,7 +4632,7 @@ int sdhci_setup_host(struct sdhci_host *host)
 	return 0;
 
 unreg:
-	if (!IS_ERR(mmc->supply.vqmmc))
+	if (host->sdhci_core_to_disable_vqmmc)
 		regulator_disable(mmc->supply.vqmmc);
 undma:
 	if (host->align_buffer)
@@ -4644,7 +4650,7 @@ void sdhci_cleanup_host(struct sdhci_host *host)
 {
 	struct mmc_host *mmc = host->mmc;
 
-	if (!IS_ERR(mmc->supply.vqmmc))
+	if (host->sdhci_core_to_disable_vqmmc)
 		regulator_disable(mmc->supply.vqmmc);
 
 	if (host->align_buffer)
@@ -4787,7 +4793,7 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)
 
 	destroy_workqueue(host->complete_wq);
 
-	if (!IS_ERR(mmc->supply.vqmmc))
+	if (host->sdhci_core_to_disable_vqmmc)
 		regulator_disable(mmc->supply.vqmmc);
 
 	if (host->align_buffer)

drivers/mmc/host/sdhci.h

@@ -567,6 +567,7 @@ struct sdhci_host {
 	u32 caps1;		/* CAPABILITY_1 */
 	bool read_caps;		/* Capability flags have been read */
 
+	bool sdhci_core_to_disable_vqmmc;  /* sdhci core can disable vqmmc */
 	unsigned int            ocr_avail_sdio;	/* OCR bit masks */
 	unsigned int            ocr_avail_sd;
 	unsigned int            ocr_avail_mmc;