mmc: sdhci-omap: Add using external dma

sdhci-omap can support both external dma controller via dmaengine framework
as well as ADMA which standard SD host controller provides.

Fixes by Faiz Abbas <fazi_abbas@ti.com>:
1. Switch to DMA slave mode when using external DMA
2. Add offset to mapbase
Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org>
Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20200116105154.7685-5-faiz_abbas@ti.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/Kconfig

@@ -1010,6 +1010,7 @@ config MMC_SDHCI_OMAP
 	depends on MMC_SDHCI_PLTFM && OF
 	select THERMAL
 	imply TI_SOC_THERMAL
+	select MMC_SDHCI_EXTERNAL_DMA if DMA_ENGINE
 	help
 	  This selects the Secure Digital Host Controller Interface (SDHCI)
 	  support present in TI's DRA7 SOCs. The controller supports

drivers/mmc/host/sdhci-omap.c

@@ -685,7 +685,11 @@ static int sdhci_omap_enable_dma(struct sdhci_host *host)
 	struct sdhci_omap_host *omap_host = sdhci_pltfm_priv(pltfm_host);
 
 	reg = sdhci_omap_readl(omap_host, SDHCI_OMAP_CON);
-	reg |= CON_DMA_MASTER;
+	reg &= ~CON_DMA_MASTER;
+	/* Switch to DMA slave mode when using external DMA */
+	if (!host->use_external_dma)
+		reg |= CON_DMA_MASTER;
+
 	sdhci_omap_writel(omap_host, SDHCI_OMAP_CON, reg);
 
 	return 0;
@@ -1037,6 +1041,7 @@ static int sdhci_omap_probe(struct platform_device *pdev)
 	const struct of_device_id *match;
 	struct sdhci_omap_data *data;
 	const struct soc_device_attribute *soc;
+	struct resource *regs;
 
 	match = of_match_device(omap_sdhci_match, dev);
 	if (!match)
@@ -1049,6 +1054,10 @@ static int sdhci_omap_probe(struct platform_device *pdev)
 	}
 	offset = data->offset;
 
+	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!regs)
+		return -ENXIO;
+
 	host = sdhci_pltfm_init(pdev, &sdhci_omap_pdata,
 				sizeof(*omap_host));
 	if (IS_ERR(host)) {
@@ -1065,6 +1074,7 @@ static int sdhci_omap_probe(struct platform_device *pdev)
 	omap_host->timing = MMC_TIMING_LEGACY;
 	omap_host->flags = data->flags;
 	host->ioaddr += offset;
+	host->mapbase = regs->start + offset;
 
 	mmc = host->mmc;
 	sdhci_get_of_property(pdev);
@@ -1134,6 +1144,10 @@ static int sdhci_omap_probe(struct platform_device *pdev)
 	host->mmc_host_ops.execute_tuning = sdhci_omap_execute_tuning;
 	host->mmc_host_ops.enable_sdio_irq = sdhci_omap_enable_sdio_irq;
 
+	/* Switch to external DMA only if there is the "dmas" property */
+	if (of_find_property(dev->of_node, "dmas", NULL))
+		sdhci_switch_external_dma(host, true);
+
 	ret = sdhci_setup_host(host);
 	if (ret)
 		goto err_put_sync;