mmc: sdhci-pxav3: add support for the Armada 38x SDHCI controller

The SDHCI unit used on the Armada 380 and 385 Marvell SoC is similar
to the PXAv3 unit. The only difference is that on Armada 38x, the
PXAv3 unit accesses memory through MBus windows which must be
configured prior to using the device. Without this, DMA would not
work.

In order to achieve this, the sdhci-pxav3 driver is extended with an
additional compatible string "marvell,armada-380-sdhci". When this
compatible string is used, the MBus windows are initialized in a way
that is identical to what all other DMA-capable drivers for Marvell
EBU platforms do.

Signed-off-by: Marcin Wojtas <mw@semihalf.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Chris Ball <chris@printf.net>

Documentation/devicetree/bindings/mmc/sdhci-pxa.txt

@@ -4,7 +4,14 @@ This file documents differences between the core properties in mmc.txt
 and the properties used by the sdhci-pxav2 and sdhci-pxav3 drivers.
 
 Required properties:
-- compatible: Should be "mrvl,pxav2-mmc" or "mrvl,pxav3-mmc".
+- compatible: Should be "mrvl,pxav2-mmc", "mrvl,pxav3-mmc" or
+  "marvell,armada-380-sdhci".
+- reg:
+  * for "mrvl,pxav2-mmc" and "mrvl,pxav3-mmc", one register area for
+    the SDHCI registers.
+  * for "marvell,armada-380-sdhci", two register areas. The first one
+    for the SDHCI registers themselves, and the second one for the
+    AXI/Mbus bridge registers of the SDHCI unit.
 
 Optional properties:
 - mrvl,clk-delay-cycles: Specify a number of cycles to delay for tuning.
@@ -19,3 +26,11 @@ sdhci@d4280800 {
 	non-removable;
 	mrvl,clk-delay-cycles = <31>;
 };
+
+sdhci@d8000 {
+	compatible = "marvell,armada-380-sdhci";
+	reg = <0xd8000 0x1000>, <0xdc000 0x100>;
+	interrupts = <0 25 0x4>;
+	clocks = <&gateclk 17>;
+	mrvl,clk-delay-cycles = <0x1F>;
+};

drivers/mmc/host/sdhci-pxav3.c

@@ -34,6 +34,7 @@
 #include <linux/of_gpio.h>
 #include <linux/pm.h>
 #include <linux/pm_runtime.h>
+#include <linux/mbus.h>
 
 #include "sdhci.h"
 #include "sdhci-pltfm.h"
@@ -57,6 +58,60 @@
 #define SDCE_MISC_INT		(1<<2)
 #define SDCE_MISC_INT_EN	(1<<1)
 
+/*
+ * These registers are relative to the second register region, for the
+ * MBus bridge.
+ */
+#define SDHCI_WINDOW_CTRL(i)	(0x80 + ((i) << 3))
+#define SDHCI_WINDOW_BASE(i)	(0x84 + ((i) << 3))
+#define SDHCI_MAX_WIN_NUM	8
+
+static int mv_conf_mbus_windows(struct platform_device *pdev,
+				const struct mbus_dram_target_info *dram)
+{
+	int i;
+	void __iomem *regs;
+	struct resource *res;
+
+	if (!dram) {
+		dev_err(&pdev->dev, "no mbus dram info\n");
+		return -EINVAL;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	if (!res) {
+		dev_err(&pdev->dev, "cannot get mbus registers\n");
+		return -EINVAL;
+	}
+
+	regs = ioremap(res->start, resource_size(res));
+	if (!regs) {
+		dev_err(&pdev->dev, "cannot map mbus registers\n");
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < SDHCI_MAX_WIN_NUM; i++) {
+		writel(0, regs + SDHCI_WINDOW_CTRL(i));
+		writel(0, regs + SDHCI_WINDOW_BASE(i));
+	}
+
+	for (i = 0; i < dram->num_cs; i++) {
+		const struct mbus_dram_window *cs = dram->cs + i;
+
+		/* Write size, attributes and target id to control register */
+		writel(((cs->size - 1) & 0xffff0000) |
+			(cs->mbus_attr << 8) |
+			(dram->mbus_dram_target_id << 4) | 1,
+			regs + SDHCI_WINDOW_CTRL(i));
+		/* Write base address to base register */
+		writel(cs->base, regs + SDHCI_WINDOW_BASE(i));
+	}
+
+	iounmap(regs);
+
+	return 0;
+}
+
 static void pxav3_set_private_registers(struct sdhci_host *host, u8 mask)
 {
 	struct platform_device *pdev = to_platform_device(mmc_dev(host->mmc));
@@ -187,6 +242,9 @@ static const struct of_device_id sdhci_pxav3_of_match[] = {
 	{
 		.compatible = "mrvl,pxav3-mmc",
 	},
+	{
+		.compatible = "marvell,armada-380-sdhci",
+	},
 	{},
 };
 MODULE_DEVICE_TABLE(of, sdhci_pxav3_of_match);
@@ -219,6 +277,7 @@ static int sdhci_pxav3_probe(struct platform_device *pdev)
 	struct sdhci_pltfm_host *pltfm_host;
 	struct sdhci_pxa_platdata *pdata = pdev->dev.platform_data;
 	struct device *dev = &pdev->dev;
+	struct device_node *np = pdev->dev.of_node;
 	struct sdhci_host *host = NULL;
 	struct sdhci_pxa *pxa = NULL;
 	const struct of_device_id *match;
@@ -235,6 +294,14 @@ static int sdhci_pxav3_probe(struct platform_device *pdev)
 		kfree(pxa);
 		return PTR_ERR(host);
 	}
+
+	if (of_device_is_compatible(np, "marvell,armada-380-sdhci")) {
+		ret = mv_conf_mbus_windows(pdev, mv_mbus_dram_info());
+		if (ret < 0)
+			goto err_mbus_win;
+	}
+
+
 	pltfm_host = sdhci_priv(host);
 	pltfm_host->priv = pxa;
 
@@ -321,6 +388,7 @@ static int sdhci_pxav3_probe(struct platform_device *pdev)
 	clk_disable_unprepare(clk);
 	clk_put(clk);
 err_clk_get:
+err_mbus_win:
 	sdhci_pltfm_free(pdev);
 	kfree(pxa);
 	return ret;