[PATCH 2/2] mmc: Add support for the ASPEED SD controller

[Andrew Jeffery]

Add a minimal driver for ASPEED's SD controller, which exposes two
SDHCIs.

The ASPEED design implements a common register set for the SDHCIs, and
moves some of the standard configuration elements out to this common
area (e.g. 8-bit mode, and card detect configuration which is not
currently supported).

The SD controller has a dedicated hardware interrupt that is shared
between the slots. The common register set exposes information on which
slot triggered the interrupt; early revisions of the patch introduced an
irqchip for the register, but reality is it doesn't behave as an
irqchip, and the result fits awkwardly into the irqchip APIs. Instead
I've taken the simple approach of using the IRQ as a shared IRQ with
some minor performance impact for the second slot.

Ryan was the original author of the patch - I've taken his work and
massaged it to drop the irqchip support and rework the devicetree
integration. The driver has been smoke tested under qemu against a
minimal SD controller model and lightly tested on an ast2500-evb.

Signed-off-by: Ryan Chen <ryanchen.aspeed@xxxxxxxxx>
Signed-off-by: Andrew Jeffery <andrew@xxxxxxxx>
---
 drivers/mmc/host/Kconfig           |  12 ++
 drivers/mmc/host/Makefile          |   1 +
 drivers/mmc/host/sdhci-of-aspeed.c | 307 +++++++++++++++++++++++++++++
 3 files changed, 320 insertions(+)
 create mode 100644 drivers/mmc/host/sdhci-of-aspeed.c

diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
index 931770f17087..2bb5e1264b3d 100644
--- a/drivers/mmc/host/Kconfig
+++ b/drivers/mmc/host/Kconfig
@@ -154,6 +154,18 @@ config MMC_SDHCI_OF_ARASAN
 
 	  If unsure, say N.
 
+config MMC_SDHCI_OF_ASPEED
+	tristate "SDHCI OF support for the ASPEED SDHCI controller"
+	depends on MMC_SDHCI_PLTFM
+	depends on OF
+	help
+	  This selects the ASPEED Secure Digital Host Controller Interface.
+
+	  If you have a controller with this interface, say Y or M here. You
+	  also need to enable an appropriate bus interface.
+
+	  If unsure, say N.
+
 config MMC_SDHCI_OF_AT91
 	tristate "SDHCI OF support for the Atmel SDMMC controller"
 	depends on MMC_SDHCI_PLTFM
diff --git a/drivers/mmc/host/Makefile b/drivers/mmc/host/Makefile
index 73578718f119..390ee162fe71 100644
--- a/drivers/mmc/host/Makefile
+++ b/drivers/mmc/host/Makefile
@@ -84,6 +84,7 @@ obj-$(CONFIG_MMC_SDHCI_ESDHC_IMX)	+= sdhci-esdhc-imx.o
 obj-$(CONFIG_MMC_SDHCI_DOVE)		+= sdhci-dove.o
 obj-$(CONFIG_MMC_SDHCI_TEGRA)		+= sdhci-tegra.o
 obj-$(CONFIG_MMC_SDHCI_OF_ARASAN)	+= sdhci-of-arasan.o
+obj-$(CONFIG_MMC_SDHCI_OF_ASPEED)	+= sdhci-of-aspeed.o
 obj-$(CONFIG_MMC_SDHCI_OF_AT91)		+= sdhci-of-at91.o
 obj-$(CONFIG_MMC_SDHCI_OF_ESDHC)	+= sdhci-of-esdhc.o
 obj-$(CONFIG_MMC_SDHCI_OF_HLWD)		+= sdhci-of-hlwd.o
diff --git a/drivers/mmc/host/sdhci-of-aspeed.c b/drivers/mmc/host/sdhci-of-aspeed.c
new file mode 100644
index 000000000000..23fad19787db
--- /dev/null
+++ b/drivers/mmc/host/sdhci-of-aspeed.c
@@ -0,0 +1,307 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* Copyright (C) 2019 ASPEED Technology Inc. */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/mmc/host.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+
+#include "sdhci-pltfm.h"
+
+#define ASPEED_SDC_INFO		0x00
+#define   ASPEED_SDC_S1MMC8	BIT(25)
+#define   ASPEED_SDC_S0MMC8	BIT(24)
+
+struct aspeed_sdc {
+	struct clk *clk;
+
+	spinlock_t lock;
+	void __iomem *regs;
+};
+
+struct aspeed_sdhci {
+	struct aspeed_sdc *parent;
+	u32 width_mask;
+};
+
+static void aspeed_sdc_bus_width(struct aspeed_sdc *sdc,
+				 struct aspeed_sdhci *sdhci, bool bus8)
+{
+	u32 info;
+
+	/* Set/clear 8 bit mode */
+	spin_lock(&sdc->lock);
+	info = readl(sdc->regs + ASPEED_SDC_INFO);
+	if (bus8)
+		info |= sdhci->width_mask;
+	else
+		info &= ~sdhci->width_mask;
+	writel(info, sdc->regs + ASPEED_SDC_INFO);
+	spin_unlock(&sdc->lock);
+}
+
+static void aspeed_sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
+{
+	unsigned long timeout;
+	int div;
+	u16 clk;
+
+	if (clock == host->clock)
+		return;
+
+	sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
+
+	if (clock == 0)
+		goto out;
+
+	for (div = 1; div < 256; div *= 2) {
+		if ((host->max_clk / div) <= clock)
+			break;
+	}
+	div >>= 1;
+
+	clk = div << SDHCI_DIVIDER_SHIFT;
+	clk |= SDHCI_CLOCK_INT_EN;
+	sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
+
+	/* Wait max 20 ms */
+	timeout = 20;
+	while (!((clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL))
+		 & SDHCI_CLOCK_INT_STABLE)) {
+		if (timeout == 0) {
+			pr_err("%s: Internal clock never stabilised.\n",
+			       mmc_hostname(host->mmc));
+			return;
+		}
+		timeout--;
+		mdelay(1);
+	}
+
+	clk |= SDHCI_CLOCK_CARD_EN;
+	sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
+
+out:
+	host->clock = clock;
+}
+
+static void aspeed_sdhci_set_bus_width(struct sdhci_host *host, int width)
+{
+	struct sdhci_pltfm_host *pltfm_priv;
+	struct aspeed_sdhci *aspeed_sdhci;
+	struct aspeed_sdc *aspeed_sdc;
+	u8 ctrl;
+
+	pltfm_priv = sdhci_priv(host);
+	aspeed_sdhci = sdhci_pltfm_priv(pltfm_priv);
+	aspeed_sdc = aspeed_sdhci->parent;
+
+	/* Set/clear 8-bit mode */
+	aspeed_sdc_bus_width(aspeed_sdc, aspeed_sdhci,
+			     width == MMC_BUS_WIDTH_8);
+
+	/* Set/clear 1 or 4 bit mode */
+	ctrl = sdhci_readb(host, SDHCI_HOST_CONTROL);
+	if (width == MMC_BUS_WIDTH_4)
+		ctrl |= SDHCI_CTRL_4BITBUS;
+	else
+		ctrl &= ~SDHCI_CTRL_4BITBUS;
+	sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
+}
+
+static const struct sdhci_ops aspeed_sdhci_ops = {
+	.set_clock = aspeed_sdhci_set_clock,
+	.get_max_clock = sdhci_pltfm_clk_get_max_clock,
+	.set_bus_width = aspeed_sdhci_set_bus_width,
+	.get_timeout_clock = sdhci_pltfm_clk_get_max_clock,
+	.reset = sdhci_reset,
+	.set_uhs_signaling = sdhci_set_uhs_signaling,
+};
+
+static const struct sdhci_pltfm_data aspeed_sdc_pdata = {
+	.ops = &aspeed_sdhci_ops,
+	.quirks = SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
+	.quirks2 = SDHCI_QUIRK2_CLOCK_DIV_ZERO_BROKEN,
+};
+
+static int aspeed_sdhci_probe(struct platform_device *pdev)
+{
+	struct sdhci_pltfm_host *pltfm_host;
+	struct aspeed_sdhci *dev;
+	struct sdhci_host *host;
+	u32 slot;
+	int ret;
+
+	host = sdhci_pltfm_init(pdev, &aspeed_sdc_pdata, sizeof(*dev));
+	if (IS_ERR(host))
+		return PTR_ERR(host);
+
+	pltfm_host = sdhci_priv(host);
+	dev = sdhci_pltfm_priv(pltfm_host);
+	dev->parent = dev_get_drvdata(pdev->dev.parent);
+
+	ret = of_property_read_u32(pdev->dev.of_node, "slot", &slot);
+	if (ret < 0)
+		return ret;
+	else if (slot > 2)
+		return -EINVAL;
+
+	dev->width_mask = !slot ? ASPEED_SDC_S0MMC8 : ASPEED_SDC_S1MMC8;
+
+	sdhci_get_of_property(pdev);
+
+	pltfm_host->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(pltfm_host->clk))
+		return PTR_ERR(pltfm_host->clk);
+
+	ret = clk_prepare_enable(pltfm_host->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "Unable to enable SDIO clock\n");
+		goto err_pltfm_free;
+	}
+
+	ret = mmc_of_parse(host->mmc);
+	if (ret)
+		goto err_sdhci_add;
+
+	ret = sdhci_add_host(host);
+	if (ret)
+		goto err_sdhci_add;
+
+	return 0;
+
+err_sdhci_add:
+	clk_disable_unprepare(pltfm_host->clk);
+err_pltfm_free:
+	sdhci_pltfm_free(pdev);
+	return ret;
+}
+
+static int aspeed_sdhci_remove(struct platform_device *pdev)
+{
+	struct sdhci_pltfm_host *pltfm_host;
+	struct sdhci_host *host;
+	int dead;
+
+	host = platform_get_drvdata(pdev);
+	pltfm_host = sdhci_priv(host);
+
+	dead = readl(host->ioaddr + SDHCI_INT_STATUS) == 0xffffffff;
+
+	sdhci_remove_host(host, dead);
+
+	clk_disable_unprepare(pltfm_host->clk);
+
+	sdhci_pltfm_free(pdev);
+
+	return 0;
+}
+
+static const struct of_device_id aspeed_sdhci_of_match[] = {
+	{ .compatible = "aspeed,ast2400-sdhci", },
+	{ .compatible = "aspeed,ast2500-sdhci", },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, aspeed_sdhci_of_match);
+
+static struct platform_driver aspeed_sdhci_driver = {
+	.driver		= {
+		.name	= "sdhci-aspeed",
+		.of_match_table = aspeed_sdhci_of_match,
+	},
+	.probe		= aspeed_sdhci_probe,
+	.remove		= aspeed_sdhci_remove,
+};
+
+module_platform_driver(aspeed_sdhci_driver);
+
+static int aspeed_sdc_probe(struct platform_device *pdev)
+
+{
+	struct device_node *parent, *child;
+	struct aspeed_sdc *sdc;
+	int ret;
+
+	sdc = devm_kzalloc(&pdev->dev, sizeof(*sdc), GFP_KERNEL);
+	if (!sdc)
+		return -ENOMEM;
+
+	spin_lock_init(&sdc->lock);
+
+	sdc->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(sdc->clk))
+		return PTR_ERR(sdc->clk);
+
+	ret = clk_prepare_enable(sdc->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "Unable to enable SDCLK\n");
+		return ret;
+	}
+
+	sdc->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(sdc->regs)) {
+		ret = PTR_ERR(sdc->regs);
+		goto err_clk;
+	}
+
+	dev_set_drvdata(&pdev->dev, sdc);
+
+	parent = pdev->dev.of_node;
+	for_each_available_child_of_node(parent, child) {
+		struct platform_device *cpdev;
+
+		cpdev = of_platform_device_create(child, NULL, &pdev->dev);
+		if (IS_ERR(cpdev)) {
+			of_node_put(child);
+			ret = PTR_ERR(pdev);
+			goto err_clk;
+		}
+	}
+
+	return 0;
+
+err_clk:
+	clk_disable_unprepare(sdc->clk);
+	return ret;
+}
+
+static int aspeed_sdc_remove(struct platform_device *pdev)
+{
+	struct aspeed_sdc *sdc = dev_get_drvdata(&pdev->dev);
+
+	clk_disable_unprepare(sdc->clk);
+
+	return 0;
+}
+
+static const struct of_device_id aspeed_sdc_of_match[] = {
+	{ .compatible = "aspeed,ast2400-sdc", .data = &aspeed_sdc_pdata },
+	{ .compatible = "aspeed,ast2500-sdc", .data = &aspeed_sdc_pdata },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(of, aspeed_sdc_of_match);
+
+static struct platform_driver aspeed_sdc_driver = {
+	.driver		= {
+		.name	= "sdc-aspeed",
+		.pm	= &sdhci_pltfm_pmops,
+		.of_match_table = aspeed_sdc_of_match,
+	},
+	.probe		= aspeed_sdc_probe,
+	.remove		= aspeed_sdc_remove,
+};
+
+module_platform_driver(aspeed_sdc_driver);
+
+MODULE_DESCRIPTION("Driver for the ASPEED SD/SDIO/SDHCI Controllers");
+MODULE_AUTHOR("Ryan Chen <ryan_chen@xxxxxxxxxxxxxx>");
+MODULE_AUTHOR("Andrew Jeffery <andrew@xxxxxxxx>");
+MODULE_LICENSE("GPL v2");
-- 
2.20.1