powerpc/512x: add LocalPlus Bus FIFO device driver

This driver for Freescale MPC512x LocalPlus Bus FIFO (called SCLPC
in the Reference Manual) allows Direct Memory Access transfers
between RAM and peripheral devices on LocalPlus Bus.

Signed-off-by: Alexander Popov <alex.popov@linux.com>
Signed-off-by: Anatolij Gustschin <agust@denx.de>

3 files changed, 547 insertions, 0 deletions

diff --git a/arch/powerpc/platforms/512x/Kconfig b/arch/powerpc/platforms/512x/Kconfig
index 48bf38d0de35..f09016f6b3a6 100644
--- a/arch/powerpc/platforms/512x/Kconfig
+++ b/arch/powerpc/platforms/512x/Kconfig
@@ -10,6 +10,12 @@ config PPC_MPC512x
 	select USB_EHCI_BIG_ENDIAN_MMIO if USB_EHCI_HCD
 	select USB_EHCI_BIG_ENDIAN_DESC if USB_EHCI_HCD
 
+config MPC512x_LPBFIFO
+	tristate "MPC512x LocalPlus Bus FIFO driver"
+	depends on PPC_MPC512x && MPC512X_DMA
+	help
+	  Enable support for Freescale MPC512x LocalPlus Bus FIFO (SCLPC).
+
 config MPC5121_ADS
 	bool "Freescale MPC5121E ADS"
 	depends on PPC_MPC512x
diff --git a/arch/powerpc/platforms/512x/Makefile b/arch/powerpc/platforms/512x/Makefile
index 01693121a2b1..f47d422953df 100644
--- a/arch/powerpc/platforms/512x/Makefile
+++ b/arch/powerpc/platforms/512x/Makefile
@@ -5,4 +5,5 @@ obj-$(CONFIG_COMMON_CLK)	+= clock-commonclk.o
 obj-y				+= mpc512x_shared.o
 obj-$(CONFIG_MPC5121_ADS)	+= mpc5121_ads.o mpc5121_ads_cpld.o
 obj-$(CONFIG_MPC512x_GENERIC)	+= mpc512x_generic.o
+obj-$(CONFIG_MPC512x_LPBFIFO)	+= mpc512x_lpbfifo.o
 obj-$(CONFIG_PDM360NG)		+= pdm360ng.o
diff --git a/arch/powerpc/platforms/512x/mpc512x_lpbfifo.c b/arch/powerpc/platforms/512x/mpc512x_lpbfifo.c
new file mode 100644
index 000000000000..8eb82b043dd8
--- /dev/null
+++ b/arch/powerpc/platforms/512x/mpc512x_lpbfifo.c
@@ -0,0 +1,540 @@
+/*
+ * The driver for Freescale MPC512x LocalPlus Bus FIFO
+ * (called SCLPC in the Reference Manual).
+ *
+ * Copyright (C) 2013-2015 Alexander Popov <alex.popov@linux.com>.
+ *
+ * This file is released under the GPLv2.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <asm/mpc5121.h>
+#include <asm/io.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-direction.h>
+#include <linux/dma-mapping.h>
+
+#define DRV_NAME "mpc512x_lpbfifo"
+
+struct cs_range {
+	u32 csnum;
+	u32 base; /* must be zero */
+	u32 addr;
+	u32 size;
+};
+
+static struct lpbfifo_data {
+	spinlock_t lock; /* for protecting lpbfifo_data */
+	phys_addr_t regs_phys;
+	resource_size_t regs_size;
+	struct mpc512x_lpbfifo __iomem *regs;
+	int irq;
+	struct cs_range *cs_ranges;
+	size_t cs_n;
+	struct dma_chan *chan;
+	struct mpc512x_lpbfifo_request *req;
+	dma_addr_t ram_bus_addr;
+	bool wait_lpbfifo_irq;
+	bool wait_lpbfifo_callback;
+} lpbfifo;
+
+/*
+ * A data transfer from RAM to some device on LPB is finished
+ * when both mpc512x_lpbfifo_irq() and mpc512x_lpbfifo_callback()
+ * have been called. We execute the callback registered in
+ * mpc512x_lpbfifo_request just after that.
+ * But for a data transfer from some device on LPB to RAM we don't enable
+ * LPBFIFO interrupt because clearing MPC512X_SCLPC_SUCCESS interrupt flag
+ * automatically disables LPBFIFO reading request to the DMA controller
+ * and the data transfer hangs. So the callback registered in
+ * mpc512x_lpbfifo_request is executed at the end of mpc512x_lpbfifo_callback().
+ */
+
+/*
+ * mpc512x_lpbfifo_irq - IRQ handler for LPB FIFO
+ */
+static irqreturn_t mpc512x_lpbfifo_irq(int irq, void *param)
+{
+	struct device *dev = (struct device *)param;
+	struct mpc512x_lpbfifo_request *req = NULL;
+	unsigned long flags;
+	u32 status;
+
+	spin_lock_irqsave(&lpbfifo.lock, flags);
+
+	if (!lpbfifo.regs)
+		goto end;
+
+	req = lpbfifo.req;
+	if (!req || req->dir == MPC512X_LPBFIFO_REQ_DIR_READ) {
+		dev_err(dev, "bogus LPBFIFO IRQ\n");
+		goto end;
+	}
+
+	status = in_be32(&lpbfifo.regs->status);
+	if (status != MPC512X_SCLPC_SUCCESS) {
+		dev_err(dev, "DMA transfer from RAM to peripheral failed\n");
+		out_be32(&lpbfifo.regs->enable,
+				MPC512X_SCLPC_RESET | MPC512X_SCLPC_FIFO_RESET);
+		goto end;
+	}
+	/* Clear the interrupt flag */
+	out_be32(&lpbfifo.regs->status, MPC512X_SCLPC_SUCCESS);
+
+	lpbfifo.wait_lpbfifo_irq = false;
+
+	if (lpbfifo.wait_lpbfifo_callback)
+		goto end;
+
+	/* Transfer is finished, set the FIFO as idle */
+	lpbfifo.req = NULL;
+
+	spin_unlock_irqrestore(&lpbfifo.lock, flags);
+
+	if (req->callback)
+		req->callback(req);
+
+	return IRQ_HANDLED;
+
+ end:
+	spin_unlock_irqrestore(&lpbfifo.lock, flags);
+	return IRQ_HANDLED;
+}
+
+/*
+ * mpc512x_lpbfifo_callback is called by DMA driver when
+ * DMA transaction is finished.
+ */
+static void mpc512x_lpbfifo_callback(void *param)
+{
+	unsigned long flags;
+	struct mpc512x_lpbfifo_request *req = NULL;
+	enum dma_data_direction dir;
+
+	spin_lock_irqsave(&lpbfifo.lock, flags);
+
+	if (!lpbfifo.regs) {
+		spin_unlock_irqrestore(&lpbfifo.lock, flags);
+		return;
+	}
+
+	req = lpbfifo.req;
+	if (!req) {
+		pr_err("bogus LPBFIFO callback\n");
+		spin_unlock_irqrestore(&lpbfifo.lock, flags);
+		return;
+	}
+
+	/* Release the mapping */
+	if (req->dir == MPC512X_LPBFIFO_REQ_DIR_WRITE)
+		dir = DMA_TO_DEVICE;
+	else
+		dir = DMA_FROM_DEVICE;
+	dma_unmap_single(lpbfifo.chan->device->dev,
+			lpbfifo.ram_bus_addr, req->size, dir);
+
+	lpbfifo.wait_lpbfifo_callback = false;
+
+	if (!lpbfifo.wait_lpbfifo_irq) {
+		/* Transfer is finished, set the FIFO as idle */
+		lpbfifo.req = NULL;
+
+		spin_unlock_irqrestore(&lpbfifo.lock, flags);
+
+		if (req->callback)
+			req->callback(req);
+	} else {
+		spin_unlock_irqrestore(&lpbfifo.lock, flags);
+	}
+}
+
+static int mpc512x_lpbfifo_kick(void)
+{
+	u32 bits;
+	bool no_incr = false;
+	u32 bpt = 32; /* max bytes per LPBFIFO transaction involving DMA */
+	u32 cs = 0;
+	size_t i;
+	struct dma_device *dma_dev = NULL;
+	struct scatterlist sg;
+	enum dma_data_direction dir;
+	struct dma_slave_config dma_conf = {};
+	struct dma_async_tx_descriptor *dma_tx = NULL;
+	dma_cookie_t cookie;
+	int ret;
+
+	/*
+	 * 1. Fit the requirements:
+	 * - the packet size must be a multiple of 4 since FIFO Data Word
+	 *    Register allows only full-word access according the Reference
+	 *    Manual;
+	 * - the physical address of the device on LPB and the packet size
+	 *    must be aligned on BPT (bytes per transaction) or 8-bytes
+	 *    boundary according the Reference Manual;
+	 * - but we choose DMA maxburst equal (or very close to) BPT to prevent
+	 *    DMA controller from overtaking FIFO and causing FIFO underflow
+	 *    error. So we force the packet size to be aligned on BPT boundary
+	 *    not to confuse DMA driver which requires the packet size to be
+	 *    aligned on maxburst boundary;
+	 * - BPT should be set to the LPB device port size for operation with
+	 *    disabled auto-incrementing according Reference Manual.
+	 */
+	if (lpbfifo.req->size == 0 || !IS_ALIGNED(lpbfifo.req->size, 4))
+		return -EINVAL;
+
+	if (lpbfifo.req->portsize != LPB_DEV_PORTSIZE_UNDEFINED) {
+		bpt = lpbfifo.req->portsize;
+		no_incr = true;
+	}
+
+	while (bpt > 1) {
+		if (IS_ALIGNED(lpbfifo.req->dev_phys_addr, min(bpt, 0x8u)) &&
+					IS_ALIGNED(lpbfifo.req->size, bpt)) {
+			break;
+		}
+
+		if (no_incr)
+			return -EINVAL;
+
+		bpt >>= 1;
+	}
+	dma_conf.dst_maxburst = max(bpt, 0x4u) / 4;
+	dma_conf.src_maxburst = max(bpt, 0x4u) / 4;
+
+	for (i = 0; i < lpbfifo.cs_n; i++) {
+		phys_addr_t cs_start = lpbfifo.cs_ranges[i].addr;
+		phys_addr_t cs_end = cs_start + lpbfifo.cs_ranges[i].size;
+		phys_addr_t access_start = lpbfifo.req->dev_phys_addr;
+		phys_addr_t access_end = access_start + lpbfifo.req->size;
+
+		if (access_start >= cs_start && access_end <= cs_end) {
+			cs = lpbfifo.cs_ranges[i].csnum;
+			break;
+		}
+	}
+	if (i == lpbfifo.cs_n)
+		return -EFAULT;
+
+	/* 2. Prepare DMA */
+	dma_dev = lpbfifo.chan->device;
+
+	if (lpbfifo.req->dir == MPC512X_LPBFIFO_REQ_DIR_WRITE) {
+		dir = DMA_TO_DEVICE;
+		dma_conf.direction = DMA_MEM_TO_DEV;
+		dma_conf.dst_addr = lpbfifo.regs_phys +
+				offsetof(struct mpc512x_lpbfifo, data_word);
+	} else {
+		dir = DMA_FROM_DEVICE;
+		dma_conf.direction = DMA_DEV_TO_MEM;
+		dma_conf.src_addr = lpbfifo.regs_phys +
+				offsetof(struct mpc512x_lpbfifo, data_word);
+	}
+	dma_conf.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+	dma_conf.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+
+	/* Make DMA channel work with LPB FIFO data register */
+	if (dma_dev->device_config(lpbfifo.chan, &dma_conf)) {
+		ret = -EINVAL;
+		goto err_dma_prep;
+	}
+
+	sg_init_table(&sg, 1);
+
+	sg_dma_address(&sg) = dma_map_single(dma_dev->dev,
+			lpbfifo.req->ram_virt_addr, lpbfifo.req->size, dir);
+	if (dma_mapping_error(dma_dev->dev, sg_dma_address(&sg)))
+		return -EFAULT;
+
+	lpbfifo.ram_bus_addr = sg_dma_address(&sg); /* For freeing later */
+
+	sg_dma_len(&sg) = lpbfifo.req->size;
+
+	dma_tx = dmaengine_prep_slave_sg(lpbfifo.chan, &sg,
+						1, dma_conf.direction, 0);
+	if (!dma_tx) {
+		ret = -ENOSPC;
+		goto err_dma_prep;
+	}
+	dma_tx->callback = mpc512x_lpbfifo_callback;
+	dma_tx->callback_param = NULL;
+
+	/* 3. Prepare FIFO */
+	out_be32(&lpbfifo.regs->enable,
+				MPC512X_SCLPC_RESET | MPC512X_SCLPC_FIFO_RESET);
+	out_be32(&lpbfifo.regs->enable, 0x0);
+
+	/*
+	 * Configure the watermarks for write operation (RAM->DMA->FIFO->dev):
+	 * - high watermark 7 words according the Reference Manual,
+	 * - low watermark 512 bytes (half of the FIFO).
+	 * These watermarks don't work for read operation since the
+	 * MPC512X_SCLPC_FLUSH bit is set (according the Reference Manual).
+	 */
+	out_be32(&lpbfifo.regs->fifo_ctrl, MPC512X_SCLPC_FIFO_CTRL(0x7));
+	out_be32(&lpbfifo.regs->fifo_alarm, MPC512X_SCLPC_FIFO_ALARM(0x200));
+
+	/*
+	 * Start address is a physical address of the region which belongs
+	 * to the device on the LocalPlus Bus
+	 */
+	out_be32(&lpbfifo.regs->start_addr, lpbfifo.req->dev_phys_addr);
+
+	/*
+	 * Configure chip select, transfer direction, address increment option
+	 * and bytes per transaction option
+	 */
+	bits = MPC512X_SCLPC_CS(cs);
+	if (lpbfifo.req->dir == MPC512X_LPBFIFO_REQ_DIR_READ)
+		bits |= MPC512X_SCLPC_READ | MPC512X_SCLPC_FLUSH;
+	if (no_incr)
+		bits |= MPC512X_SCLPC_DAI;
+	bits |= MPC512X_SCLPC_BPT(bpt);
+	out_be32(&lpbfifo.regs->ctrl, bits);
+
+	/* Unmask irqs */
+	bits = MPC512X_SCLPC_ENABLE | MPC512X_SCLPC_ABORT_INT_ENABLE;
+	if (lpbfifo.req->dir == MPC512X_LPBFIFO_REQ_DIR_WRITE)
+		bits |= MPC512X_SCLPC_NORM_INT_ENABLE;
+	else
+		lpbfifo.wait_lpbfifo_irq = false;
+
+	out_be32(&lpbfifo.regs->enable, bits);
+
+	/* 4. Set packet size and kick FIFO off */
+	bits = lpbfifo.req->size | MPC512X_SCLPC_START;
+	out_be32(&lpbfifo.regs->pkt_size, bits);
+
+	/* 5. Finally kick DMA off */
+	cookie = dma_tx->tx_submit(dma_tx);
+	if (dma_submit_error(cookie)) {
+		ret = -ENOSPC;
+		goto err_dma_submit;
+	}
+
+	return 0;
+
+ err_dma_submit:
+	out_be32(&lpbfifo.regs->enable,
+				MPC512X_SCLPC_RESET | MPC512X_SCLPC_FIFO_RESET);
+ err_dma_prep:
+	dma_unmap_single(dma_dev->dev, sg_dma_address(&sg),
+						lpbfifo.req->size, dir);
+	return ret;
+}
+
+static int mpc512x_lpbfifo_submit_locked(struct mpc512x_lpbfifo_request *req)
+{
+	int ret = 0;
+
+	if (!lpbfifo.regs)
+		return -ENODEV;
+
+	/* Check whether a transfer is in progress */
+	if (lpbfifo.req)
+		return -EBUSY;
+
+	lpbfifo.wait_lpbfifo_irq = true;
+	lpbfifo.wait_lpbfifo_callback = true;
+	lpbfifo.req = req;
+
+	ret = mpc512x_lpbfifo_kick();
+	if (ret != 0)
+		lpbfifo.req = NULL; /* Set the FIFO as idle */
+
+	return ret;
+}
+
+int mpc512x_lpbfifo_submit(struct mpc512x_lpbfifo_request *req)
+{
+	unsigned long flags;
+	int ret = 0;
+
+	spin_lock_irqsave(&lpbfifo.lock, flags);
+	ret = mpc512x_lpbfifo_submit_locked(req);
+	spin_unlock_irqrestore(&lpbfifo.lock, flags);
+
+	return ret;
+}
+EXPORT_SYMBOL(mpc512x_lpbfifo_submit);
+
+/*
+ * LPBFIFO driver uses "ranges" property of "localbus" device tree node
+ * for being able to determine the chip select number of a client device
+ * ordering a DMA transfer.
+ */
+static int get_cs_ranges(struct device *dev)
+{
+	int ret = -ENODEV;
+	struct device_node *lb_node;
+	const u32 *addr_cells_p;
+	const u32 *size_cells_p;
+	int proplen;
+	size_t i;
+
+	lb_node = of_find_compatible_node(NULL, NULL, "fsl,mpc5121-localbus");
+	if (!lb_node)
+		return ret;
+
+	/*
+	 * The node defined as compatible with 'fsl,mpc5121-localbus'
+	 * should have two address cells and one size cell.
+	 * Every item of its ranges property should consist of:
+	 * - the first address cell which is the chipselect number;
+	 * - the second address cell which is the offset in the chipselect,
+	 *    must be zero.
+	 * - CPU address of the beginning of an access window;
+	 * - the only size cell which is the size of an access window.
+	 */
+	addr_cells_p = of_get_property(lb_node, "#address-cells", NULL);
+	size_cells_p = of_get_property(lb_node, "#size-cells", NULL);
+	if (addr_cells_p == NULL || *addr_cells_p != 2 ||
+				size_cells_p == NULL ||	*size_cells_p != 1) {
+		goto end;
+	}
+
+	proplen = of_property_count_u32_elems(lb_node, "ranges");
+	if (proplen <= 0 || proplen % 4 != 0)
+		goto end;
+
+	lpbfifo.cs_n = proplen / 4;
+	lpbfifo.cs_ranges = devm_kcalloc(dev, lpbfifo.cs_n,
+					sizeof(struct cs_range), GFP_KERNEL);
+	if (!lpbfifo.cs_ranges)
+		goto end;
+
+	if (of_property_read_u32_array(lb_node, "ranges",
+				(u32 *)lpbfifo.cs_ranges, proplen) != 0) {
+		goto end;
+	}
+
+	for (i = 0; i < lpbfifo.cs_n; i++) {
+		if (lpbfifo.cs_ranges[i].base != 0)
+			goto end;
+	}
+
+	ret = 0;
+
+ end:
+	of_node_put(lb_node);
+	return ret;
+}
+
+static int mpc512x_lpbfifo_probe(struct platform_device *pdev)
+{
+	struct resource r;
+	int ret = 0;
+
+	memset(&lpbfifo, 0, sizeof(struct lpbfifo_data));
+	spin_lock_init(&lpbfifo.lock);
+
+	lpbfifo.chan = dma_request_slave_channel(&pdev->dev, "rx-tx");
+	if (lpbfifo.chan == NULL)
+		return -EPROBE_DEFER;
+
+	if (of_address_to_resource(pdev->dev.of_node, 0, &r) != 0) {
+		dev_err(&pdev->dev, "bad 'reg' in 'sclpc' device tree node\n");
+		ret = -ENODEV;
+		goto err0;
+	}
+
+	lpbfifo.regs_phys = r.start;
+	lpbfifo.regs_size = resource_size(&r);
+
+	if (!devm_request_mem_region(&pdev->dev, lpbfifo.regs_phys,
+					lpbfifo.regs_size, DRV_NAME)) {
+		dev_err(&pdev->dev, "unable to request region\n");
+		ret = -EBUSY;
+		goto err0;
+	}
+
+	lpbfifo.regs = devm_ioremap(&pdev->dev,
+					lpbfifo.regs_phys, lpbfifo.regs_size);
+	if (!lpbfifo.regs) {
+		dev_err(&pdev->dev, "mapping registers failed\n");
+		ret = -ENOMEM;
+		goto err0;
+	}
+
+	out_be32(&lpbfifo.regs->enable,
+				MPC512X_SCLPC_RESET | MPC512X_SCLPC_FIFO_RESET);
+
+	if (get_cs_ranges(&pdev->dev) != 0) {
+		dev_err(&pdev->dev, "bad '/localbus' device tree node\n");
+		ret = -ENODEV;
+		goto err0;
+	}
+
+	lpbfifo.irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
+	if (lpbfifo.irq == NO_IRQ) {
+		dev_err(&pdev->dev, "mapping irq failed\n");
+		ret = -ENODEV;
+		goto err0;
+	}
+
+	if (request_irq(lpbfifo.irq, mpc512x_lpbfifo_irq, 0,
+						DRV_NAME, &pdev->dev) != 0) {
+		dev_err(&pdev->dev, "requesting irq failed\n");
+		ret = -ENODEV;
+		goto err1;
+	}
+
+	dev_info(&pdev->dev, "probe succeeded\n");
+	return 0;
+
+ err1:
+	irq_dispose_mapping(lpbfifo.irq);
+ err0:
+	dma_release_channel(lpbfifo.chan);
+	return ret;
+}
+
+static int mpc512x_lpbfifo_remove(struct platform_device *pdev)
+{
+	unsigned long flags;
+	struct dma_device *dma_dev = lpbfifo.chan->device;
+	struct mpc512x_lpbfifo __iomem *regs = NULL;
+
+	spin_lock_irqsave(&lpbfifo.lock, flags);
+	regs = lpbfifo.regs;
+	lpbfifo.regs = NULL;
+	spin_unlock_irqrestore(&lpbfifo.lock, flags);
+
+	dma_dev->device_terminate_all(lpbfifo.chan);
+	out_be32(&regs->enable, MPC512X_SCLPC_RESET | MPC512X_SCLPC_FIFO_RESET);
+
+	free_irq(lpbfifo.irq, &pdev->dev);
+	irq_dispose_mapping(lpbfifo.irq);
+	dma_release_channel(lpbfifo.chan);
+
+	return 0;
+}
+
+static const struct of_device_id mpc512x_lpbfifo_match[] = {
+	{ .compatible = "fsl,mpc512x-lpbfifo", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, mpc512x_lpbfifo_match);
+
+static struct platform_driver mpc512x_lpbfifo_driver = {
+	.probe = mpc512x_lpbfifo_probe,
+	.remove = mpc512x_lpbfifo_remove,
+	.driver = {
+		.name = DRV_NAME,
+		.owner = THIS_MODULE,
+		.of_match_table = mpc512x_lpbfifo_match,
+	},
+};
+
+module_platform_driver(mpc512x_lpbfifo_driver);
+
+MODULE_AUTHOR("Alexander Popov <alex.popov@linux.com>");
+MODULE_DESCRIPTION("MPC512x LocalPlus Bus FIFO device driver");
+MODULE_LICENSE("GPL v2");