[PATCHv2 3/3] fpga manager: Adding FPGA Manager support for Xilinx Zynq 7000

[Moritz Fischer]

This commit adds FPGA Manager support for the Xilinx Zynq chip.
The code borrows some from the xdevcfg driver in Xilinx'
vendor tree.

Signed-off-by: Moritz Fischer <moritz.fischer@xxxxxxxxx>
---

v2:
 - Replaced locking error flag and broken completion with irq masking
   and changed completion handling
 - Dealing with timeout cases
 - Reworked clock handling
 - Moved initialization from probe() to write_init()
 - Fixed return value of devm_request_irq() check to check for non-zero
 - Alphabetized includes ;-)
 - Changed some of the comments, to better explain what's happening

---
 drivers/fpga/Kconfig     |   5 +
 drivers/fpga/Makefile    |   1 +
 drivers/fpga/zynq-fpga.c | 533 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 539 insertions(+)
 create mode 100644 drivers/fpga/zynq-fpga.c

diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
index dfc1f1e..c9b9fdf 100644
--- a/drivers/fpga/Kconfig
+++ b/drivers/fpga/Kconfig
@@ -19,6 +19,11 @@ config FPGA_MGR_SOCFPGA
 	help
 	  FPGA manager driver support for Altera SOCFPGA.
 
+config FPGA_MGR_ZYNQ_FPGA
+	tristate "Xilinx Zynq FPGA"
+	help
+	  FPGA manager driver support for Xilinx Zynq FPGAs.
+
 endif # FPGA
 
 endmenu
diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
index ba6c5c5..8d83fc6 100644
--- a/drivers/fpga/Makefile
+++ b/drivers/fpga/Makefile
@@ -7,3 +7,4 @@ obj-$(CONFIG_FPGA)			+= fpga-mgr.o
 
 # FPGA Manager Drivers
 obj-$(CONFIG_FPGA_MGR_SOCFPGA)		+= socfpga.o
+obj-$(CONFIG_FPGA_MGR_ZYNQ_FPGA)	+= zynq-fpga.o
diff --git a/drivers/fpga/zynq-fpga.c b/drivers/fpga/zynq-fpga.c
new file mode 100644
index 0000000..103303c
--- /dev/null
+++ b/drivers/fpga/zynq-fpga.c
@@ -0,0 +1,533 @@
+/*
+ * Copyright (c) 2011-2015 Xilinx Inc.
+ * Copyright (c) 2015, National Instruments Corp.
+ *
+ * FPGA Manager Driver for Xilinx Zynq, heavily based on xdevcfg driver
+ * in their vendor tree.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/dma-mapping.h>
+#include <linux/fpga/fpga-mgr.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/pm.h>
+#include <linux/regmap.h>
+#include <linux/string.h>
+
+/* Offsets into SLCR regmap */
+
+/* FPGA Software Reset Control */
+#define SLCR_FPGA_RST_CTRL_OFFSET	0x240
+/* Level Shifters Enable */
+#define SLCR_LVL_SHFTR_EN_OFFSET	0x900
+
+/* Constant Definitions */
+
+/* Control Register */
+#define CTRL_OFFSET			0x00
+/* Lock Register */
+#define LOCK_OFFSET			0x04
+/* Interrupt Status Register */
+#define INT_STS_OFFSET			0x0c
+/* Interrupt Mask Register */
+#define INT_MASK_OFFSET			0x10
+/* Status Register */
+#define STATUS_OFFSET			0x14
+/* DMA Source Address Register */
+#define DMA_SRC_ADDR_OFFSET		0x18
+/* DMA Destination Address Reg */
+#define DMA_DST_ADDR_OFFSET		0x1c
+/* DMA Source Transfer Length */
+#define DMA_SRC_LEN_OFFSET		0x20
+/* DMA Destination Transfer */
+#define DMA_DEST_LEN_OFFSET		0x24
+/* Unlock Register */
+#define UNLOCK_OFFSET			0x34
+/* Misc. Control Register */
+#define MCTRL_OFFSET			0x80
+
+/* Control Register Bit definitions */
+
+/* Signal to reset FPGA */
+#define CTRL_PCFG_PROG_B_MASK		BIT(30)
+/* Enable PCAP for PR */
+#define CTRL_PCAP_PR_MASK		BIT(27)
+/* Enable PCAP */
+#define CTRL_PCAP_MODE_MASK		BIT(26)
+
+/* Miscellaneous Control Register bit definitions */
+/* Internal PCAP loopback */
+#define MCTRL_PCAP_LPBK_MASK		BIT(4)
+
+/* Status register bit definitions */
+
+/* FPGA init status */
+#define STATUS_DMA_Q_F			BIT(31)
+#define STATUS_PCFG_INIT_MASK		BIT(4)
+
+/* Interrupt Status/Mask Register Bit definitions */
+/* DMA command done */
+#define IXR_DMA_DONE_MASK		BIT(13)
+/* DMA and PCAP cmd done */
+#define IXR_D_P_DONE_MASK		BIT(12)
+ /* FPGA programmed */
+#define IXR_PCFG_DONE_MASK		BIT(2)
+#define IXR_ERROR_FLAGS_MASK		0x00F0F860
+#define IXR_ALL_MASK			0xF8F7F87F
+
+/* Miscellaneous constant values */
+
+/* Invalid DMA addr */
+#define DMA_INVALID_ADDRESS		GENMASK(31, 0)
+/* Used to unlock the dev */
+#define UNLOCK_MASK			0x757bdf0d
+/* Timeout for DMA to complete */
+#define DMA_DONE_TIMEOUT		msecs_to_jiffies(1000)
+/* Timeout for polling reset bits */
+#define INIT_POLL_TIMEOUT		2500000
+/* Delay for polling reset bits */
+#define INIT_POLL_DELAY			20
+
+/* Masks for controlling stuff in SLCR */
+/* Disable all Level shifters */
+#define LVL_SHFTR_DISABLE_ALL_MASK	0x0
+/* Enable Level shifters from PS to PL */
+#define LVL_SHFTR_ENABLE_PS_TO_PL	0xa
+/* Enable Level shifters from PL to PS */
+#define LVL_SHFTR_ENABLE_PL_TO_PS	0xf
+/* Enable global resets */
+#define FPGA_RST_ALL_MASK		0xf
+/* Disable global resets */
+#define FPGA_RST_NONE_MASK		0x0
+
+struct zynq_fpga_priv {
+	struct device *dev;
+	int irq;
+	struct clk *clk;
+
+	void __iomem *io_base;
+	struct regmap *slcr;
+
+	struct completion dma_done;
+};
+
+static inline void zynq_fpga_write(struct zynq_fpga_priv *priv, u32 offset,
+				   u32 val)
+{
+	writel(val, priv->io_base + offset);
+}
+
+static inline u32 zynq_fpga_read(const struct zynq_fpga_priv *priv,
+				 u32 offset)
+{
+	return readl(priv->io_base + offset);
+}
+
+#define zynq_fpga_poll_timeout(priv, addr, val, cond, sleep_us, timeout_us) \
+	readl_poll_timeout(priv->io_base + addr, val, cond, sleep_us, \
+			   timeout_us)
+
+static void zynq_fpga_mask_irqs(struct zynq_fpga_priv *priv)
+{
+	u32 intr_mask;
+
+	intr_mask = zynq_fpga_read(priv, INT_MASK_OFFSET);
+	zynq_fpga_write(priv, INT_MASK_OFFSET,
+			intr_mask | IXR_DMA_DONE_MASK | IXR_ERROR_FLAGS_MASK);
+}
+
+static void zynq_fpga_unmask_irqs(struct zynq_fpga_priv *priv)
+{
+	u32 intr_mask;
+
+	intr_mask = zynq_fpga_read(priv, INT_MASK_OFFSET);
+	zynq_fpga_write(priv, INT_MASK_OFFSET,
+			intr_mask
+			& ~(IXR_D_P_DONE_MASK | IXR_ERROR_FLAGS_MASK));
+}
+
+static irqreturn_t zynq_fpga_isr(int irq, void *data)
+{
+	struct zynq_fpga_priv *priv = data;
+
+	/* disable DMA and error IRQs */
+	zynq_fpga_mask_irqs(priv);
+
+	complete(&priv->dma_done);
+
+	return IRQ_HANDLED;
+}
+
+static int zynq_fpga_ops_write_init(struct fpga_manager *mgr, u32 flags,
+				    const char *buf, size_t count)
+{
+	struct zynq_fpga_priv *priv;
+	u32 ctrl, status;
+	int err;
+
+	priv = mgr->priv;
+
+	err = clk_enable(priv->clk);
+	if (err)
+		return err;
+
+	/* don't globally reset PL if we're doing partial reconfig */
+	if (!(flags & FPGA_MGR_PARTIAL_RECONFIG)) {
+		/* assert AXI interface resets */
+		regmap_write(priv->slcr, SLCR_FPGA_RST_CTRL_OFFSET,
+			     FPGA_RST_ALL_MASK);
+
+		/* disable all level shifters */
+		regmap_write(priv->slcr, SLCR_LVL_SHFTR_EN_OFFSET,
+			     LVL_SHFTR_DISABLE_ALL_MASK);
+		/* enable level shifters from PS to PL */
+		regmap_write(priv->slcr, SLCR_LVL_SHFTR_EN_OFFSET,
+			     LVL_SHFTR_ENABLE_PS_TO_PL);
+
+		/* create a rising edge on PCFG_INIT. PCFG_INIT follows
+		 * PCFG_PROG_B, so we need to poll it after setting PCFG_PROG_B
+		 * to make sure the rising edge actually happens.
+		 * Note: PCFG_PROG_B is low active, sequence as described in
+		 * UG585 v1.10 page 211
+		 */
+		ctrl = zynq_fpga_read(priv, CTRL_OFFSET);
+		ctrl |= CTRL_PCFG_PROG_B_MASK;
+
+		zynq_fpga_write(priv, CTRL_OFFSET, ctrl);
+
+		err = zynq_fpga_poll_timeout(priv, STATUS_OFFSET, status,
+					     status & STATUS_PCFG_INIT_MASK,
+					     INIT_POLL_DELAY,
+					     INIT_POLL_TIMEOUT);
+		if (err) {
+			dev_err(priv->dev, "Timeout waiting for PCFG_INIT");
+			goto out_err;
+		}
+
+		ctrl = zynq_fpga_read(priv, CTRL_OFFSET);
+		ctrl &= ~CTRL_PCFG_PROG_B_MASK;
+
+		zynq_fpga_write(priv, CTRL_OFFSET, ctrl);
+
+		err = zynq_fpga_poll_timeout(priv, STATUS_OFFSET, status,
+					     !(status & STATUS_PCFG_INIT_MASK),
+					     INIT_POLL_DELAY,
+					     INIT_POLL_TIMEOUT);
+		if (err) {
+			dev_err(priv->dev, "Timeout waiting for !PCFG_INIT");
+			goto out_err;
+		}
+
+		ctrl = zynq_fpga_read(priv, CTRL_OFFSET);
+		ctrl |= CTRL_PCFG_PROG_B_MASK;
+
+		zynq_fpga_write(priv, CTRL_OFFSET, ctrl);
+
+		err = zynq_fpga_poll_timeout(priv, STATUS_OFFSET, status,
+					     status & STATUS_PCFG_INIT_MASK,
+					     INIT_POLL_DELAY,
+					     INIT_POLL_TIMEOUT);
+		if (err) {
+			dev_err(priv->dev, "Timeout waiting for PCFG_INIT");
+			goto out_err;
+		}
+	}
+
+	/* set configuration register with following options:
+	 * - enable PCAP interface
+	 * - set throughput for maximum speed
+	 * - set CPU in user mode
+	 */
+	ctrl = zynq_fpga_read(priv, CTRL_OFFSET);
+	zynq_fpga_write(priv, CTRL_OFFSET,
+			(CTRL_PCAP_PR_MASK | CTRL_PCAP_MODE_MASK | ctrl));
+
+	/* check that we have room in the command queue */
+	status = zynq_fpga_read(priv, STATUS_OFFSET);
+	if (status & STATUS_DMA_Q_F) {
+		dev_err(priv->dev, "DMA command queue full");
+		err = -EBUSY;
+		goto out_err;
+	}
+
+	/* ensure internal PCAP loopback is disabled */
+	ctrl = zynq_fpga_read(priv, MCTRL_OFFSET);
+	zynq_fpga_write(priv, MCTRL_OFFSET, (~MCTRL_PCAP_LPBK_MASK & ctrl));
+
+	clk_disable(priv->clk);
+
+	return 0;
+
+out_err:
+	clk_disable(priv->clk);
+
+	return err;
+}
+
+static int zynq_fpga_ops_write(struct fpga_manager *mgr,
+			       const char *buf, size_t count)
+{
+	struct zynq_fpga_priv *priv;
+	int err;
+	char *kbuf;
+	size_t i, in_count;
+	dma_addr_t dma_addr;
+	u32 transfer_length = 0;
+	u32 intr_status;
+
+	in_count = count;
+	priv = mgr->priv;
+
+	kbuf = dma_alloc_coherent(priv->dev, count, &dma_addr, GFP_KERNEL);
+	if (!kbuf)
+		return -ENOMEM;
+
+	memcpy(kbuf, buf, count);
+
+	/* look for the sync word */
+	for (i = 0; i < count - 4; i++) {
+		if (memcmp(kbuf + i, "\xAA\x99\x55\x66", 4) == 0) {
+			dev_dbg(priv->dev, "Found swapped sync word\n");
+			break;
+		}
+	}
+
+	/* remove the header, align the data on word boundary */
+	if (i != count - 4) {
+		count -= i;
+		memmove(kbuf, kbuf + i, count);
+	}
+
+	/* fixup endianness of the data */
+	for (i = 0; i < count; i += 4) {
+		u32 *p = (u32 *)&kbuf[i];
+		*p = swab32(*p);
+	}
+
+	/* enable clock */
+	err = clk_enable(priv->clk);
+	if (err)
+		goto out_free;
+
+	zynq_fpga_write(priv, INT_STS_OFFSET, IXR_ALL_MASK);
+
+	reinit_completion(&priv->dma_done);
+
+	/* enable DMA and error IRQs */
+	zynq_fpga_unmask_irqs(priv);
+
+	/* the +1 in the src addr is used to hold off on DMA_DONE IRQ
+	 * until both AXI and PCAP are done ...
+	 */
+	zynq_fpga_write(priv, DMA_SRC_ADDR_OFFSET, (u32)(dma_addr) + 1);
+	zynq_fpga_write(priv, DMA_DST_ADDR_OFFSET, (u32)DMA_INVALID_ADDRESS);
+
+	/* convert #bytes to #words */
+	transfer_length = (count + 3) / 4;
+
+	zynq_fpga_write(priv, DMA_SRC_LEN_OFFSET, transfer_length);
+	zynq_fpga_write(priv, DMA_DEST_LEN_OFFSET, 0);
+
+	wait_for_completion(&priv->dma_done);
+
+	intr_status = zynq_fpga_read(priv, INT_STS_OFFSET);
+	zynq_fpga_write(priv, INT_STS_OFFSET, intr_status);
+
+	if (!((intr_status & IXR_D_P_DONE_MASK) == IXR_D_P_DONE_MASK)) {
+		dev_err(priv->dev, "Error configuring FPGA");
+		err = -EFAULT;
+	}
+
+	clk_disable(priv->clk);
+
+out_free:
+	dma_free_coherent(priv->dev, in_count, kbuf, dma_addr);
+
+	return err;
+}
+
+static int zynq_fpga_ops_write_complete(struct fpga_manager *mgr, u32 flags)
+{
+	struct zynq_fpga_priv *priv = mgr->priv;
+	int err;
+	u32 intr_status;
+
+	err = clk_enable(priv->clk);
+	if (err)
+		return err;
+
+	err = zynq_fpga_poll_timeout(priv, INT_STS_OFFSET, intr_status,
+				     intr_status & IXR_PCFG_DONE_MASK,
+				     INIT_POLL_DELAY,
+				     INIT_POLL_TIMEOUT);
+
+	clk_disable(priv->clk);
+
+	if (err)
+		return err;
+
+	/* for the partial reconfig case we didn't touch the level shifters */
+	if (!(flags & FPGA_MGR_PARTIAL_RECONFIG)) {
+		/* enable level shifters from PL to PS */
+		regmap_write(priv->slcr, SLCR_LVL_SHFTR_EN_OFFSET,
+			     LVL_SHFTR_ENABLE_PL_TO_PS);
+
+		/* deassert AXI interface resets */
+		regmap_write(priv->slcr, SLCR_FPGA_RST_CTRL_OFFSET,
+			     FPGA_RST_NONE_MASK);
+	}
+
+	return 0;
+}
+
+static enum fpga_mgr_states zynq_fpga_ops_state(struct fpga_manager *mgr)
+{
+	int err;
+	u32 intr_status;
+	struct zynq_fpga_priv *priv;
+
+	priv = mgr->priv;
+
+	err = clk_enable(priv->clk);
+	if (err)
+		return FPGA_MGR_STATE_UNKNOWN;
+
+	intr_status = zynq_fpga_read(priv, INT_STS_OFFSET);
+	clk_disable(priv->clk);
+
+	if (intr_status & IXR_PCFG_DONE_MASK)
+		return FPGA_MGR_STATE_OPERATING;
+
+	return FPGA_MGR_STATE_UNKNOWN;
+}
+
+static const struct fpga_manager_ops zynq_fpga_ops = {
+	.state = zynq_fpga_ops_state,
+	.write_init = zynq_fpga_ops_write_init,
+	.write = zynq_fpga_ops_write,
+	.write_complete = zynq_fpga_ops_write_complete,
+};
+
+static int zynq_fpga_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct zynq_fpga_priv *priv;
+	struct resource *res;
+	int err;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, priv);
+	priv->dev = dev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	priv->io_base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(priv->io_base))
+		return PTR_ERR(priv->io_base);
+
+	priv->slcr = syscon_regmap_lookup_by_phandle(dev->of_node,
+		"syscon");
+	if (IS_ERR(priv->slcr)) {
+		dev_err(dev, "unable to get zynq-slcr regmap");
+		return PTR_ERR(priv->slcr);
+	}
+
+	init_completion(&priv->dma_done);
+
+	priv->irq = platform_get_irq(pdev, 0);
+	if (priv->irq < 0) {
+		dev_err(dev, "No IRQ available");
+		return priv->irq;
+	}
+
+	err = devm_request_irq(dev, priv->irq, zynq_fpga_isr, 0,
+			       dev_name(dev), priv);
+	if (err) {
+		dev_err(dev, "unable to request IRQ");
+		return err;
+	}
+
+	priv->clk = devm_clk_get(dev, "ref_clk");
+	if (IS_ERR(priv->clk)) {
+		dev_err(dev, "input clock not found");
+		return PTR_ERR(priv->clk);
+	}
+
+	err = clk_prepare_enable(priv->clk);
+	if (err) {
+		dev_err(dev, "unable to enable clock");
+		return err;
+	}
+
+	/* unlock the device */
+	zynq_fpga_write(priv, UNLOCK_OFFSET, UNLOCK_MASK);
+
+	clk_disable(priv->clk);
+
+	err = fpga_mgr_register(dev, "Xilinx Zynq FPGA Manager",
+				&zynq_fpga_ops, priv);
+	if (err) {
+		dev_err(dev, "unable to register FPGA manager");
+		clk_disable_unprepare(priv->clk);
+		return err;
+	}
+
+	return 0;
+}
+
+static int zynq_fpga_remove(struct platform_device *pdev)
+{
+	struct zynq_fpga_priv *priv;
+
+	fpga_mgr_unregister(&pdev->dev);
+
+	priv = platform_get_drvdata(pdev);
+
+	clk_disable_unprepare(priv->clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id zynq_fpga_of_match[] = {
+	{ .compatible = "xlnx,zynq-devcfg-1.0", },
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, zynq_fpga_of_match);
+#endif
+
+static struct platform_driver zynq_fpga_driver = {
+	.probe = zynq_fpga_probe,
+	.remove = zynq_fpga_remove,
+	.driver = {
+		.name = "zynq_fpga_manager",
+		.of_match_table = of_match_ptr(zynq_fpga_of_match),
+	},
+};
+
+module_platform_driver(zynq_fpga_driver);
+
+MODULE_AUTHOR("Moritz Fischer <moritz.fischer@xxxxxxxxx>");
+MODULE_AUTHOR("Michal Simek <michal.simek@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Xilinx Zynq FPGA Manager");
+MODULE_LICENSE("GPL v2");
-- 
2.4.3

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