fpga: Add support for Xilinx LogiCORE PR Decoupler

This adds support for the Xilinx LogiCORE PR Decoupler
soft-ip that does decoupling of PR regions in the FPGA
fabric during partial reconfiguration.

Signed-off-by: Moritz Fischer <mdf@kernel.org>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Cc: Sören Brinkmann <soren.brinkmann@xilinx.com>
Cc: linux-kernel@vger.kernel.org
Cc: devicetree@vger.kernel.org
Acked-by: Alan Tull <atull@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 172 insertions, 0 deletions

diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
index 116ee92fe034..161ba9dccede 100644
--- a/drivers/fpga/Kconfig
+++ b/drivers/fpga/Kconfig
@@ -95,6 +95,16 @@ config ALTERA_PR_IP_CORE_PLAT
           Platform driver support for Altera Partial Reconfiguration IP
           component
 
+config XILINX_PR_DECOUPLER
+        tristate "Xilinx LogiCORE PR Decoupler"
+        depends on FPGA_BRIDGE
+        depends on HAS_IOMEM
+        help
+          Say Y to enable drivers for Xilinx LogiCORE PR Decoupler.
+          The PR Decoupler exists in the FPGA fabric to isolate one
+          region of the FPGA from the busses while that region is
+          being reprogrammed during partial reconfig.
+
 endif # FPGA
 
 endmenu
diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
index 530cf9410dde..2a4f0218145c 100644
--- a/drivers/fpga/Makefile
+++ b/drivers/fpga/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_ALTERA_PR_IP_CORE_PLAT)    += altera-pr-ip-core-plat.o
 obj-$(CONFIG_FPGA_BRIDGE)               += fpga-bridge.o
 obj-$(CONFIG_SOCFPGA_FPGA_BRIDGE)       += altera-hps2fpga.o altera-fpga2sdram.o
 obj-$(CONFIG_ALTERA_FREEZE_BRIDGE)      += altera-freeze-bridge.o
+obj-$(CONFIG_XILINX_PR_DECOUPLER)       += xilinx-pr-decoupler.o
 
 # High Level Interfaces
 obj-$(CONFIG_FPGA_REGION)               += fpga-region.o
diff --git a/drivers/fpga/xilinx-pr-decoupler.c b/drivers/fpga/xilinx-pr-decoupler.c
new file mode 100644
index 000000000000..e359930bebc8
--- /dev/null
+++ b/drivers/fpga/xilinx-pr-decoupler.c
@@ -0,0 +1,161 @@
+/*
+ * Copyright (c) 2017, National Instruments Corp.
+ * Copyright (c) 2017, Xilix Inc
+ *
+ * FPGA Bridge Driver for the Xilinx LogiCORE Partial Reconfiguration
+ * Decoupler IP Core.
+ *
+ * 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/io.h>
+#include <linux/kernel.h>
+#include <linux/of_device.h>
+#include <linux/module.h>
+#include <linux/fpga/fpga-bridge.h>
+
+#define CTRL_CMD_DECOUPLE       BIT(0)
+#define CTRL_CMD_COUPLE         0
+#define CTRL_OFFSET             0
+
+struct xlnx_pr_decoupler_data {
+        void __iomem *io_base;
+        struct clk *clk;
+};
+
+static inline void xlnx_pr_decoupler_write(struct xlnx_pr_decoupler_data *d,
+                                           u32 offset, u32 val)
+{
+        writel(val, d->io_base + offset);
+}
+
+static inline u32 xlnx_pr_decouple_read(const struct xlnx_pr_decoupler_data *d,
+                                        u32 offset)
+{
+        return readl(d->io_base + offset);
+}
+
+static int xlnx_pr_decoupler_enable_set(struct fpga_bridge *bridge, bool enable)
+{
+        int err;
+        struct xlnx_pr_decoupler_data *priv = bridge->priv;
+
+        err = clk_enable(priv->clk);
+        if (err)
+                return err;
+
+        if (enable)
+                xlnx_pr_decoupler_write(priv, CTRL_OFFSET, CTRL_CMD_COUPLE);
+        else
+                xlnx_pr_decoupler_write(priv, CTRL_OFFSET, CTRL_CMD_DECOUPLE);
+
+        clk_disable(priv->clk);
+
+        return 0;
+}
+
+static int xlnx_pr_decoupler_enable_show(struct fpga_bridge *bridge)
+{
+        const struct xlnx_pr_decoupler_data *priv = bridge->priv;
+        u32 status;
+        int err;
+
+        err = clk_enable(priv->clk);
+        if (err)
+                return err;
+
+        status = readl(priv->io_base);
+
+        clk_disable(priv->clk);
+
+        return !status;
+}
+
+static struct fpga_bridge_ops xlnx_pr_decoupler_br_ops = {
+        .enable_set = xlnx_pr_decoupler_enable_set,
+        .enable_show = xlnx_pr_decoupler_enable_show,
+};
+
+static const struct of_device_id xlnx_pr_decoupler_of_match[] = {
+        { .compatible = "xlnx,pr-decoupler-1.00", },
+        { .compatible = "xlnx,pr-decoupler", },
+        {},
+};
+MODULE_DEVICE_TABLE(of, xlnx_pr_decoupler_of_match);
+
+static int xlnx_pr_decoupler_probe(struct platform_device *pdev)
+{
+        struct xlnx_pr_decoupler_data *priv;
+        int err;
+        struct resource *res;
+
+        priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+        if (!priv)
+                return -ENOMEM;
+
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        priv->io_base = devm_ioremap_resource(&pdev->dev, res);
+        if (IS_ERR(priv->io_base))
+                return PTR_ERR(priv->io_base);
+
+        priv->clk = devm_clk_get(&pdev->dev, "aclk");
+        if (IS_ERR(priv->clk)) {
+                dev_err(&pdev->dev, "input clock not found\n");
+                return PTR_ERR(priv->clk);
+        }
+
+        err = clk_prepare_enable(priv->clk);
+        if (err) {
+                dev_err(&pdev->dev, "unable to enable clock\n");
+                return err;
+        }
+
+        clk_disable(priv->clk);
+
+        err = fpga_bridge_register(&pdev->dev, "Xilinx PR Decoupler",
+                                   &xlnx_pr_decoupler_br_ops, priv);
+
+        if (err) {
+                dev_err(&pdev->dev, "unable to register Xilinx PR Decoupler");
+                clk_unprepare(priv->clk);
+                return err;
+        }
+
+        return 0;
+}
+
+static int xlnx_pr_decoupler_remove(struct platform_device *pdev)
+{
+        struct fpga_bridge *bridge = platform_get_drvdata(pdev);
+        struct xlnx_pr_decoupler_data *p = bridge->priv;
+
+        fpga_bridge_unregister(&pdev->dev);
+
+        clk_unprepare(p->clk);
+
+        return 0;
+}
+
+static struct platform_driver xlnx_pr_decoupler_driver = {
+        .probe = xlnx_pr_decoupler_probe,
+        .remove = xlnx_pr_decoupler_remove,
+        .driver = {
+                .name = "xlnx_pr_decoupler",
+                .of_match_table = of_match_ptr(xlnx_pr_decoupler_of_match),
+        },
+};
+
+module_platform_driver(xlnx_pr_decoupler_driver);
+
+MODULE_DESCRIPTION("Xilinx Partial Reconfiguration Decoupler");
+MODULE_AUTHOR("Moritz Fischer <mdf@kernel.org>");
+MODULE_AUTHOR("Michal Simek <michal.simek@xilinx.com>");
+MODULE_LICENSE("GPL v2");