[PATCH v3] mmc: mxs-mmc: Introduce regulator support

[Martin Kepplinger <martink@posteo.de>]

From: Martin Kepplinger <martin.kepplinger@ginzinger.com>

This adds support for explicitly switching the mmc's power on and off
which is needed for example for WL1837 WL1271 wifi controllers on imx28.

While the wifi's vmmc-supply regulator can be configured in devicetree,
"ip link set wlan0 down" doesn't turn off the VMMC regulator which leads
to hangs when loading firmware, for example.

Signed-off-by: Martin Kepplinger <martin.kepplinger@ginzinger.com>
---

Thanks Ulf for your review and keeping this up with the current API.            
                                                                                
                            martin                                              
                                                                                
                                                                                
revision history                                                                
----------------                                                                
v3: improve API usage as suggested by Ulf
v2: tested patch with changes suggested by Robin                                
v1: question, why https://patchwork.kernel.org/patch/4365751/ didn't get in



 drivers/mmc/host/mxs-mmc.c | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/drivers/mmc/host/mxs-mmc.c b/drivers/mmc/host/mxs-mmc.c
index add1e70195ea..af6068152929 100644
--- a/drivers/mmc/host/mxs-mmc.c
+++ b/drivers/mmc/host/mxs-mmc.c
@@ -517,6 +517,27 @@ static void mxs_mmc_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 	else
 		host->bus_width = 0;
 
+	if (host->mmc->supply.vmmc &&
+	    ios->power_mode != host->mmc->ios.power_mode) {
+		switch (ios->power_mode) {
+		case MMC_POWER_OFF:
+			if (mmc_regulator_set_ocr(host->mmc,
+						  host->mmc->supply.vmmc, 0))
+				dev_err(mmc_dev(host->mmc),
+					"Failed to disable vmmc regulator\n");
+			break;
+		case MMC_POWER_UP:
+			if (mmc_regulator_set_ocr(host->mmc,
+						  host->mmc->supply.vmmc,
+						  ios->vdd))
+				dev_err(mmc_dev(host->mmc),
+					"Failed to enable vmmc regulator\n");
+			break;
+		default:
+			break;
+		}
+	}
+
 	if (ios->clock)
 		mxs_ssp_set_clk_rate(&host->ssp, ios->clock);
 }
@@ -588,7 +609,6 @@ static int mxs_mmc_probe(struct platform_device *pdev)
 	struct mmc_host *mmc;
 	struct resource *iores;
 	int ret = 0, irq_err;
-	struct regulator *reg_vmmc;
 	struct mxs_ssp *ssp;
 
 	irq_err = platform_get_irq(pdev, 0);
@@ -614,15 +634,9 @@ static int mxs_mmc_probe(struct platform_device *pdev)
 	host->mmc = mmc;
 	host->sdio_irq_en = 0;
 
-	reg_vmmc = devm_regulator_get(&pdev->dev, "vmmc");
-	if (!IS_ERR(reg_vmmc)) {
-		ret = regulator_enable(reg_vmmc);
-		if (ret) {
-			dev_err(&pdev->dev,
-				"Failed to enable vmmc regulator: %d\n", ret);
-			goto out_mmc_free;
-		}
-	}
+	ret = mmc_regulator_get_supply(mmc);
+	if (ret)
+		goto out_mmc_free;
 
 	ssp->clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(ssp->clk)) {
-- 
2.20.1