[PATCH v3 2/2] dmaengine: uniphier-mdmac: add UniPhier MIO DMAC driver

[Masahiro Yamada]

The MIO DMAC (Media IO DMA Controller) is used in UniPhier LD4,
Pro4, and sLD8 SoCs.

Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
---

Changes in v3:
 - Get residue from on-flight chunk
 - Use GFP_NOWAIT instead of GFP_KERNEL in prep_slave_sg
 - Use device_config hook
 - Add NULL pointer check for txstate

Changes in v2:
 - Use platform_irq_count() to get the number of channels

 MAINTAINERS                  |   1 +
 drivers/dma/Kconfig          |  11 +
 drivers/dma/Makefile         |   1 +
 drivers/dma/uniphier-mdmac.c | 495 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 508 insertions(+)
 create mode 100644 drivers/dma/uniphier-mdmac.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 82ea427..5c0794a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2193,6 +2193,7 @@ F:	arch/arm/mm/cache-uniphier.c
 F:	arch/arm64/boot/dts/socionext/uniphier*
 F:	drivers/bus/uniphier-system-bus.c
 F:	drivers/clk/uniphier/
+F:	drivers/dmaengine/uniphier-mdmac.c
 F:	drivers/gpio/gpio-uniphier.c
 F:	drivers/i2c/busses/i2c-uniphier*
 F:	drivers/irqchip/irq-uniphier-aidet.c
diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index dacf3f4..8b8c7f0 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -576,6 +576,17 @@ config TIMB_DMA
 	help
 	  Enable support for the Timberdale FPGA DMA engine.
 
+config UNIPHIER_MDMAC
+	tristate "UniPhier MIO DMAC"
+	depends on ARCH_UNIPHIER || COMPILE_TEST
+	depends on OF
+	select DMA_ENGINE
+	select DMA_VIRTUAL_CHANNELS
+	help
+	  Enable support for the MIO DMAC (Media I/O DMA controller) on the
+	  UniPhier platform.  This DMA controller is used as the external
+	  DMA engine of the SD/eMMC controllers of the LD4, Pro4, sLD8 SoCs.
+
 config XGENE_DMA
 	tristate "APM X-Gene DMA support"
 	depends on ARCH_XGENE || COMPILE_TEST
diff --git a/drivers/dma/Makefile b/drivers/dma/Makefile
index c91702d..973a170 100644
--- a/drivers/dma/Makefile
+++ b/drivers/dma/Makefile
@@ -69,6 +69,7 @@ obj-$(CONFIG_TXX9_DMAC) += txx9dmac.o
 obj-$(CONFIG_TEGRA20_APB_DMA) += tegra20-apb-dma.o
 obj-$(CONFIG_TEGRA210_ADMA) += tegra210-adma.o
 obj-$(CONFIG_TIMB_DMA) += timb_dma.o
+obj-$(CONFIG_UNIPHIER_MDMAC) += uniphier-mdmac.o
 obj-$(CONFIG_XGENE_DMA) += xgene-dma.o
 obj-$(CONFIG_ZX_DMA) += zx_dma.o
 obj-$(CONFIG_ST_FDMA) += st_fdma.o
diff --git a/drivers/dma/uniphier-mdmac.c b/drivers/dma/uniphier-mdmac.c
new file mode 100644
index 0000000..e620dbf
--- /dev/null
+++ b/drivers/dma/uniphier-mdmac.c
@@ -0,0 +1,495 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (C) 2018 Socionext Inc.
+//   Author: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
+
+#include <linux/clk.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/interrupt.h>
+#include <linux/iopoll.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_dma.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#include "virt-dma.h"
+
+/* registers common for all channels */
+#define UNIPHIER_MDMAC_CMD		0x000	// issue DMA start/abort
+#define   UNIPHIER_MDMAC_CMD_ABORT		BIT(31) // 1: abort, 0: start
+
+/* per-channel registers */
+#define UNIPHIER_MDMAC_CH_OFFSET	0x100
+#define UNIPHIER_MDMAC_CH_STRIDE	0x040
+
+#define UNIPHIER_MDMAC_CH_IRQ_STAT	0x010	// current hw status (RO)
+#define UNIPHIER_MDMAC_CH_IRQ_REQ	0x014	// latched STAT (WOC)
+#define UNIPHIER_MDMAC_CH_IRQ_EN	0x018	// IRQ enable mask
+#define UNIPHIER_MDMAC_CH_IRQ_DET	0x01c	// REQ & EN (RO)
+#define   UNIPHIER_MDMAC_CH_IRQ__ABORT		BIT(13)
+#define   UNIPHIER_MDMAC_CH_IRQ__DONE		BIT(1)
+#define UNIPHIER_MDMAC_CH_SRC_MODE	0x020	// mode of source
+#define UNIPHIER_MDMAC_CH_DEST_MODE	0x024	// mode of destination
+#define   UNIPHIER_MDMAC_CH_MODE__ADDR_INC	(0 << 4)
+#define   UNIPHIER_MDMAC_CH_MODE__ADDR_DEC	(1 << 4)
+#define   UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED	(2 << 4)
+#define UNIPHIER_MDMAC_CH_SRC_ADDR	0x028	// source address
+#define UNIPHIER_MDMAC_CH_DEST_ADDR	0x02c	// destination address
+#define UNIPHIER_MDMAC_CH_SIZE		0x030	// transfer bytes
+
+struct uniphier_mdmac_desc {
+	struct virt_dma_desc vd;
+	struct scatterlist *sgl;
+	unsigned int sg_len;
+	unsigned int sg_cur;
+	enum dma_transfer_direction dir;
+};
+
+struct uniphier_mdmac_chan {
+	struct virt_dma_chan vc;
+	struct uniphier_mdmac_device *mdev;
+	struct uniphier_mdmac_desc *md;
+	void __iomem *reg_ch_base;
+	unsigned int chan_id;
+};
+
+struct uniphier_mdmac_device {
+	struct dma_device ddev;
+	struct clk *clk;
+	void __iomem *reg_base;
+	struct uniphier_mdmac_chan channels[0];
+};
+
+static struct uniphier_mdmac_chan *to_uniphier_mdmac_chan(
+						struct virt_dma_chan *vc)
+{
+	return container_of(vc, struct uniphier_mdmac_chan, vc);
+}
+
+static struct uniphier_mdmac_desc *to_uniphier_mdmac_desc(
+						struct virt_dma_desc *vd)
+{
+	return container_of(vd, struct uniphier_mdmac_desc, vd);
+}
+
+/* mc->vc.lock must be held by caller */
+static struct uniphier_mdmac_desc *__uniphier_mdmac_next_desc(
+						struct uniphier_mdmac_chan *mc)
+{
+	struct virt_dma_desc *vd;
+
+	vd = vchan_next_desc(&mc->vc);
+	if (!vd) {
+		mc->md = NULL;
+		return NULL;
+	}
+
+	list_del(&vd->node);
+
+	mc->md = to_uniphier_mdmac_desc(vd);
+
+	return mc->md;
+}
+
+/* mc->vc.lock must be held by caller */
+static void __uniphier_mdmac_handle(struct uniphier_mdmac_chan *mc,
+				    struct uniphier_mdmac_desc *md)
+{
+	struct uniphier_mdmac_device *mdev = mc->mdev;
+	struct scatterlist *sg;
+	u32 irq_flag = UNIPHIER_MDMAC_CH_IRQ__DONE;
+	u32 src_mode, src_addr, dest_mode, dest_addr, chunk_size;
+
+	sg = &md->sgl[md->sg_cur];
+
+	if (md->dir == DMA_MEM_TO_DEV) {
+		src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
+		src_addr = sg_dma_address(sg);
+		dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
+		dest_addr = 0;
+	} else {
+		src_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_FIXED;
+		src_addr = 0;
+		dest_mode = UNIPHIER_MDMAC_CH_MODE__ADDR_INC;
+		dest_addr = sg_dma_address(sg);
+	}
+
+	chunk_size = sg_dma_len(sg);
+
+	writel(src_mode, mc->reg_ch_base + UNIPHIER_MDMAC_CH_SRC_MODE);
+	writel(dest_mode, mc->reg_ch_base + UNIPHIER_MDMAC_CH_DEST_MODE);
+	writel(src_addr, mc->reg_ch_base + UNIPHIER_MDMAC_CH_SRC_ADDR);
+	writel(dest_addr, mc->reg_ch_base + UNIPHIER_MDMAC_CH_DEST_ADDR);
+	writel(chunk_size, mc->reg_ch_base + UNIPHIER_MDMAC_CH_SIZE);
+
+	/* write 1 to clear */
+	writel(irq_flag, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ);
+
+	writel(irq_flag, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_EN);
+
+	writel(BIT(mc->chan_id), mdev->reg_base + UNIPHIER_MDMAC_CMD);
+}
+
+/* mc->vc.lock must be held by caller */
+static void __uniphier_mdmac_start(struct uniphier_mdmac_chan *mc)
+{
+	struct uniphier_mdmac_desc *md;
+
+	md = __uniphier_mdmac_next_desc(mc);
+	if (md)
+		__uniphier_mdmac_handle(mc, md);
+}
+
+/* mc->vc.lock must be held by caller */
+static int __uniphier_mdmac_abort(struct uniphier_mdmac_chan *mc)
+{
+	struct uniphier_mdmac_device *mdev = mc->mdev;
+	u32 irq_flag = UNIPHIER_MDMAC_CH_IRQ__ABORT;
+	u32 val;
+
+	/* write 1 to clear */
+	writel(irq_flag, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ);
+
+	writel(UNIPHIER_MDMAC_CMD_ABORT | BIT(mc->chan_id),
+	       mdev->reg_base + UNIPHIER_MDMAC_CMD);
+
+	/*
+	 * Abort should be accepted soon. We poll the bit here instead of
+	 * waiting for the interrupt.
+	 */
+	return readl_poll_timeout(mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ,
+				  val, val & irq_flag, 0, 20);
+}
+
+/* mc->vc.lock must be held by caller */
+static u32 __uniphier_mdmac_get_residue(struct uniphier_mdmac_chan *mc,
+					struct uniphier_mdmac_desc *md)
+{
+	u32 residue;
+	int i;
+
+	/* residue from the on-flight chunk */
+	residue = readl(mc->reg_ch_base + UNIPHIER_MDMAC_CH_SIZE);
+
+	/* residue from the queued chunks */
+	for (i = md->sg_cur; i < md->sg_len; i++)
+		residue += sg_dma_len(&md->sgl[i]);
+
+	return residue;
+}
+
+static irqreturn_t uniphier_mdmac_interrupt(int irq, void *dev_id)
+{
+	struct uniphier_mdmac_chan *mc = dev_id;
+	struct uniphier_mdmac_desc *md;
+	irqreturn_t ret = IRQ_HANDLED;
+	u32 irq_stat;
+
+	spin_lock(&mc->vc.lock);
+
+	irq_stat = readl(mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_DET);
+
+	/*
+	 * Some channels share a single interrupt line. If the IRQ status is 0,
+	 * this is probably triggered by a different channel.
+	 */
+	if (!irq_stat) {
+		ret = IRQ_NONE;
+		goto out;
+	}
+
+	/* write 1 to clear */
+	writel(irq_stat, mc->reg_ch_base + UNIPHIER_MDMAC_CH_IRQ_REQ);
+
+	/*
+	 * UNIPHIER_MDMAC_CH_IRQ__DONE interrupt is asserted even when the DMA
+	 * is aborted.  To distinguish the normal completion and the abort,
+	 * check mc->md.  If it is NULL, we are aborting.
+	 */
+	md = mc->md;
+	if (!md)
+		goto out;
+
+	md->sg_cur++;
+
+	if (md->sg_cur >= md->sg_len) {
+		vchan_cookie_complete(&md->vd);
+		md = __uniphier_mdmac_next_desc(mc);
+		if (!md)
+			goto out;
+	}
+
+	__uniphier_mdmac_handle(mc, md);
+
+out:
+	spin_unlock(&mc->vc.lock);
+
+	return ret;
+}
+
+static struct dma_async_tx_descriptor *uniphier_mdmac_prep_slave_sg(
+					struct dma_chan *chan,
+					struct scatterlist *sgl,
+					unsigned int sg_len,
+					enum dma_transfer_direction direction,
+					unsigned long flags, void *context)
+{
+	struct virt_dma_chan *vc = to_virt_chan(chan);
+	struct uniphier_mdmac_desc *md;
+
+	if (!is_slave_direction(direction))
+		return NULL;
+
+	md = kzalloc(sizeof(*md), GFP_NOWAIT);
+	if (!md)
+		return NULL;
+
+	md->sgl = sgl;
+	md->sg_len = sg_len;
+	md->dir = direction;
+
+	return vchan_tx_prep(vc, &md->vd, flags);
+}
+
+static int uniphier_mdmac_config(struct dma_chan *chan,
+				 struct dma_slave_config *config)
+{
+	/* Nothing in struct dma_slave_config is configurable. */
+	return 0;
+}
+
+static int uniphier_mdmac_terminate_all(struct dma_chan *chan)
+{
+	struct virt_dma_chan *vc = to_virt_chan(chan);
+	struct uniphier_mdmac_chan *mc = to_uniphier_mdmac_chan(vc);
+	unsigned long flags;
+	int ret = 0;
+	LIST_HEAD(head);
+
+	spin_lock_irqsave(&vc->lock, flags);
+
+	if (mc->md) {
+		vchan_terminate_vdesc(&mc->md->vd);
+		mc->md = NULL;
+		ret = __uniphier_mdmac_abort(mc);
+	}
+	vchan_get_all_descriptors(vc, &head);
+
+	spin_unlock_irqrestore(&vc->lock, flags);
+
+	vchan_dma_desc_free_list(vc, &head);
+
+	return ret;
+}
+
+static void uniphier_mdmac_synchronize(struct dma_chan *chan)
+{
+	vchan_synchronize(to_virt_chan(chan));
+}
+
+static enum dma_status uniphier_mdmac_tx_status(struct dma_chan *chan,
+						dma_cookie_t cookie,
+						struct dma_tx_state *txstate)
+{
+	struct virt_dma_chan *vc;
+	struct virt_dma_desc *vd;
+	struct uniphier_mdmac_chan *mc;
+	struct uniphier_mdmac_desc *md = NULL;
+	enum dma_status stat;
+	unsigned long flags;
+
+	stat = dma_cookie_status(chan, cookie, txstate);
+	/* Return immediately if we do not need to compute the residue. */
+	if (stat == DMA_COMPLETE || !txstate)
+		return stat;
+
+	vc = to_virt_chan(chan);
+
+	spin_lock_irqsave(&vc->lock, flags);
+
+	mc = to_uniphier_mdmac_chan(vc);
+
+	if (mc->md && mc->md->vd.tx.cookie == cookie)
+		md = mc->md;
+
+	if (!md) {
+		vd = vchan_find_desc(vc, cookie);
+		if (vd)
+			md = to_uniphier_mdmac_desc(vd);
+	}
+
+	if (md)
+		txstate->residue = __uniphier_mdmac_get_residue(mc, md);
+
+	spin_unlock_irqrestore(&vc->lock, flags);
+
+	return stat;
+}
+
+static void uniphier_mdmac_issue_pending(struct dma_chan *chan)
+{
+	struct virt_dma_chan *vc = to_virt_chan(chan);
+	struct uniphier_mdmac_chan *mc = to_uniphier_mdmac_chan(vc);
+	unsigned long flags;
+
+	spin_lock_irqsave(&vc->lock, flags);
+
+	if (vchan_issue_pending(vc) && !mc->md)
+		__uniphier_mdmac_start(mc);
+
+	spin_unlock_irqrestore(&vc->lock, flags);
+}
+
+static void uniphier_mdmac_desc_free(struct virt_dma_desc *vd)
+{
+	kfree(to_uniphier_mdmac_desc(vd));
+}
+
+static int uniphier_mdmac_chan_init(struct platform_device *pdev,
+				    struct uniphier_mdmac_device *mdev,
+				    int chan_id)
+{
+	struct device *dev = &pdev->dev;
+	struct uniphier_mdmac_chan *mc = &mdev->channels[chan_id];
+	char *irq_name;
+	int irq, ret;
+
+	irq = platform_get_irq(pdev, chan_id);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "failed to get IRQ number for ch%d\n",
+			chan_id);
+		return irq;
+	}
+
+	irq_name = devm_kasprintf(dev, GFP_KERNEL, "uniphier-mio-dmac-ch%d",
+				  chan_id);
+	if (!irq_name)
+		return -ENOMEM;
+
+	ret = devm_request_irq(dev, irq, uniphier_mdmac_interrupt,
+			       IRQF_SHARED, irq_name, mc);
+	if (ret)
+		return ret;
+
+	mc->mdev = mdev;
+	mc->reg_ch_base = mdev->reg_base + UNIPHIER_MDMAC_CH_OFFSET +
+					UNIPHIER_MDMAC_CH_STRIDE * chan_id;
+	mc->chan_id = chan_id;
+	mc->vc.desc_free = uniphier_mdmac_desc_free;
+	vchan_init(&mc->vc, &mdev->ddev);
+
+	return 0;
+}
+
+static int uniphier_mdmac_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct uniphier_mdmac_device *mdev;
+	struct dma_device *ddev;
+	struct resource *res;
+	int nr_chans, ret, i;
+
+	nr_chans = platform_irq_count(pdev);
+	if (nr_chans < 0)
+		return nr_chans;
+
+	ret = dma_set_mask(dev, DMA_BIT_MASK(32));
+	if (ret)
+		return ret;
+
+	mdev = devm_kzalloc(dev, struct_size(mdev, channels, nr_chans),
+			    GFP_KERNEL);
+	if (!mdev)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	mdev->reg_base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(mdev->reg_base))
+		return PTR_ERR(mdev->reg_base);
+
+	mdev->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(mdev->clk)) {
+		dev_err(dev, "failed to get clock\n");
+		return PTR_ERR(mdev->clk);
+	}
+
+	ret = clk_prepare_enable(mdev->clk);
+	if (ret)
+		return ret;
+
+	ddev = &mdev->ddev;
+	ddev->dev = dev;
+	dma_cap_set(DMA_PRIVATE, ddev->cap_mask);
+	ddev->src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED);
+	ddev->dst_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_UNDEFINED);
+	ddev->directions = BIT(DMA_MEM_TO_DEV) | BIT(DMA_DEV_TO_MEM);
+	ddev->residue_granularity = DMA_RESIDUE_GRANULARITY_SEGMENT;
+	ddev->device_prep_slave_sg = uniphier_mdmac_prep_slave_sg;
+	ddev->device_config = uniphier_mdmac_config;
+	ddev->device_terminate_all = uniphier_mdmac_terminate_all;
+	ddev->device_synchronize = uniphier_mdmac_synchronize;
+	ddev->device_tx_status = uniphier_mdmac_tx_status;
+	ddev->device_issue_pending = uniphier_mdmac_issue_pending;
+	INIT_LIST_HEAD(&ddev->channels);
+
+	for (i = 0; i < nr_chans; i++) {
+		ret = uniphier_mdmac_chan_init(pdev, mdev, i);
+		if (ret)
+			goto disable_clk;
+	}
+
+	ret = dma_async_device_register(ddev);
+	if (ret)
+		goto disable_clk;
+
+	ret = of_dma_controller_register(dev->of_node, of_dma_xlate_by_chan_id,
+					 ddev);
+	if (ret)
+		goto unregister_dmac;
+
+	platform_set_drvdata(pdev, mdev);
+
+	return 0;
+
+unregister_dmac:
+	dma_async_device_unregister(ddev);
+disable_clk:
+	clk_disable_unprepare(mdev->clk);
+
+	return ret;
+}
+
+static int uniphier_mdmac_remove(struct platform_device *pdev)
+{
+	struct uniphier_mdmac_device *mdev = platform_get_drvdata(pdev);
+
+	of_dma_controller_free(pdev->dev.of_node);
+	dma_async_device_unregister(&mdev->ddev);
+	clk_disable_unprepare(mdev->clk);
+
+	return 0;
+}
+
+static const struct of_device_id uniphier_mdmac_match[] = {
+	{ .compatible = "socionext,uniphier-mio-dmac" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, uniphier_mdmac_match);
+
+static struct platform_driver uniphier_mdmac_driver = {
+	.probe = uniphier_mdmac_probe,
+	.remove = uniphier_mdmac_remove,
+	.driver = {
+		.name = "uniphier-mio-dmac",
+		.of_match_table = uniphier_mdmac_match,
+	},
+};
+module_platform_driver(uniphier_mdmac_driver);
+
+MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>");
+MODULE_DESCRIPTION("UniPhier MIO DMAC driver");
+MODULE_LICENSE("GPL v2");
-- 
2.7.4