Re: [PATCH 2/2] fpga: Add support for Xilinx LogiCORE PR Decoupler

[Moritz Fischer]

On Fri, Mar 10, 2017 at 1:30 PM, Moritz Fischer <mdf@xxxxxxxxxx> wrote:
> 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@xxxxxxxxxx>
> Cc: Michal Simek <michal.simek@xxxxxxxxxx>
> Cc: SÃren Brinkmann <soren.brinkmann@xxxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: devicetree@xxxxxxxxxxxxxxx
> ---
>  drivers/fpga/Kconfig               |   9 +++
>  drivers/fpga/Makefile              |   1 +
>  drivers/fpga/xilinx-pr-decoupler.c | 156 +++++++++++++++++++++++++++++++++++++
>  3 files changed, 166 insertions(+)
>  create mode 100644 drivers/fpga/xilinx-pr-decoupler.c
>
> diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
> index 967cda4..e42c7dc 100644
> --- a/drivers/fpga/Kconfig
> +++ b/drivers/fpga/Kconfig
> @@ -69,6 +69,15 @@ config ALTERA_FREEZE_BRIDGE
>           isolate one region of the FPGA from the busses while that
>           region is being reprogrammed.
>
> +config XILINX_PR_DECOUPLER
> +       tristate "Xilinx LogiCORE PR Decoupler"
> +       depends on FPGA_BRIDGE
> +       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 cc0d364..3f04bcf 100644
> --- a/drivers/fpga/Makefile
> +++ b/drivers/fpga/Makefile
> @@ -15,6 +15,7 @@ obj-$(CONFIG_FPGA_MGR_ZYNQ_FPGA)      += zynq-fpga.o
>  obj-$(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 0000000..07afdd6
> --- /dev/null
> +++ b/drivers/fpga/xilinx-pr-decoupler.c
> @@ -0,0 +1,156 @@
> +/*
> + * Copyright (c) 2017, National Instruments Corp.
> + *
> + * 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_OFFSET 0x00
> +#define STATUS_OFFSET 0x00
> +
> +#define CTRL_CMD_MASK          BIT(0)
> +#define CTRL_CMD_DECOUPLE      BIT(0)
> +#define CTRL_CMD_COUPLE                ~BIT(0)
> +
> +#define STATUS_STATE_MASK      BIT(0)
> +#define STATUS_STATE_COUPLED   ~BIT(0)
> +#define STATUS_STATE_DECOUPLED BIT(0)
> +
> +struct xlnx_pr_decoupler_data {
> +       void __iomem *io_base;
> +       struct clk *clk;
> +       bool enable;
> +};
> +
> +static inline void xlnx_pr_decoupler_write(struct xlnx_pr_decoupler_data *p,
> +                                          u32 offset, u32 val)
> +{
> +       writel(val, p->io_base + offset);
> +}
> +
> +static inline u32 xlnx_pr_decoupler_read(const struct xlnx_pr_decoupler_data *p,
> +                                        u32 offset)
> +{
> +       return readl(p->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;
> +
> +       if (priv->enable != enable) {
> +               err = clk_enable(priv->clk);
> +               if (err)
> +                       return err;
> +
> +               xlnx_pr_decoupler_write(priv, CTRL_OFFSET,
> +                                       enable ? CTRL_CMD_COUPLE :
> +                                       CTRL_CMD_DECOUPLE);
Needs:

+ priv->enable = enable;

This is obviously garbage, priv->enable doesn't get set ...

> +               clk_disable(priv->clk);
> +       }
> +
> +       return 0;
> +}
> +
> +static int xlnx_pr_decoupler_enable_show(struct fpga_bridge *bridge)
> +{
> +       const struct xlnx_pr_decoupler_data *p = bridge->priv;
> +
> +       return p->enable;
> +}
> +
> +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", },
> +       {},
> +};
> +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;
> +       u32 status;
> +       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, "ref_clk");
> +       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;
> +       }
> +
> +       status = xlnx_pr_decoupler_read(priv, STATUS_OFFSET);
> +       priv->enable = !!(status & STATUS_STATE_MASK);
> +
> +       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)
> +{
> +       fpga_bridge_unregister(&pdev->dev);
> +
> +       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@xxxxxxxxxx>");
> +MODULE_LICENSE("GPL v2");
> --
> 2.7.4
>
> --
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