fpga: xilinx-selectmap: add new driver

Xilinx 7 series FPGA can be programmed using a parallel port named
the SelectMAP interface in the datasheet. This interface is compatible
with the i.MX6 EIM bus controller but other types of external memory
mapped parallel bus might work.

xilinx-selectmap currently only supports the x8 mode where data is loaded
at one byte per rising edge of the clock, with the MSb of each byte
presented to the D0 pin.

Signed-off-by: Charles Perry <charles.perry@savoirfairelinux.com>
[yilun.xu@linux.intel.com: replace data type of i from u32 to size_t]
Acked-by: Xu Yilun <yilun.xu@intel.com>
Link: https://lore.kernel.org/r/20240321220447.3260065-4-charles.perry@savoirfairelinux.com
Signed-off-by: Xu Yilun <yilun.xu@linux.intel.com>

drivers/fpga/Kconfig

@@ -67,6 +67,14 @@ config FPGA_MGR_STRATIX10_SOC
 config FPGA_MGR_XILINX_CORE
 	tristate
 
+config FPGA_MGR_XILINX_SELECTMAP
+	tristate "Xilinx Configuration over SelectMAP"
+	depends on HAS_IOMEM
+	select FPGA_MGR_XILINX_CORE
+	help
+	  FPGA manager driver support for Xilinx FPGA configuration
+	  over SelectMAP interface.
+
 config FPGA_MGR_XILINX_SPI
 	tristate "Xilinx Configuration over Slave Serial (SPI)"
 	depends on SPI

drivers/fpga/Makefile

@@ -16,6 +16,7 @@ obj-$(CONFIG_FPGA_MGR_SOCFPGA_A10)	+= socfpga-a10.o
 obj-$(CONFIG_FPGA_MGR_STRATIX10_SOC)	+= stratix10-soc.o
 obj-$(CONFIG_FPGA_MGR_TS73XX)		+= ts73xx-fpga.o
 obj-$(CONFIG_FPGA_MGR_XILINX_CORE)	+= xilinx-core.o
+obj-$(CONFIG_FPGA_MGR_XILINX_SELECTMAP)	+= xilinx-selectmap.o
 obj-$(CONFIG_FPGA_MGR_XILINX_SPI)	+= xilinx-spi.o
 obj-$(CONFIG_FPGA_MGR_ZYNQ_FPGA)	+= zynq-fpga.o
 obj-$(CONFIG_FPGA_MGR_ZYNQMP_FPGA)	+= zynqmp-fpga.o

drivers/fpga/xilinx-selectmap.c

@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Xilinx Spartan6 and 7 Series SelectMAP interface driver
+ *
+ * (C) 2024 Charles Perry <charles.perry@savoirfairelinux.com>
+ *
+ * Manage Xilinx FPGA firmware loaded over the SelectMAP configuration
+ * interface.
+ */
+
+#include "xilinx-core.h"
+
+#include <linux/gpio/consumer.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+struct xilinx_selectmap_conf {
+	struct xilinx_fpga_core core;
+	void __iomem *base;
+};
+
+#define to_xilinx_selectmap_conf(obj) \
+	container_of(obj, struct xilinx_selectmap_conf, core)
+
+static int xilinx_selectmap_write(struct xilinx_fpga_core *core,
+				  const char *buf, size_t count)
+{
+	struct xilinx_selectmap_conf *conf = to_xilinx_selectmap_conf(core);
+	size_t i;
+
+	for (i = 0; i < count; ++i)
+		writeb(buf[i], conf->base);
+
+	return 0;
+}
+
+static int xilinx_selectmap_probe(struct platform_device *pdev)
+{
+	struct xilinx_selectmap_conf *conf;
+	struct gpio_desc *gpio;
+	void __iomem *base;
+
+	conf = devm_kzalloc(&pdev->dev, sizeof(*conf), GFP_KERNEL);
+	if (!conf)
+		return -ENOMEM;
+
+	conf->core.dev = &pdev->dev;
+	conf->core.write = xilinx_selectmap_write;
+
+	base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
+	if (IS_ERR(base))
+		return dev_err_probe(&pdev->dev, PTR_ERR(base),
+				     "ioremap error\n");
+	conf->base = base;
+
+	/* CSI_B is active low */
+	gpio = devm_gpiod_get_optional(&pdev->dev, "csi", GPIOD_OUT_HIGH);
+	if (IS_ERR(gpio))
+		return dev_err_probe(&pdev->dev, PTR_ERR(gpio),
+				     "Failed to get CSI_B gpio\n");
+
+	/* RDWR_B is active low */
+	gpio = devm_gpiod_get_optional(&pdev->dev, "rdwr", GPIOD_OUT_HIGH);
+	if (IS_ERR(gpio))
+		return dev_err_probe(&pdev->dev, PTR_ERR(gpio),
+				     "Failed to get RDWR_B gpio\n");
+
+	return xilinx_core_probe(&conf->core);
+}
+
+static const struct of_device_id xlnx_selectmap_of_match[] = {
+	{ .compatible = "xlnx,fpga-xc7s-selectmap", }, // Spartan-7
+	{ .compatible = "xlnx,fpga-xc7a-selectmap", }, // Artix-7
+	{ .compatible = "xlnx,fpga-xc7k-selectmap", }, // Kintex-7
+	{ .compatible = "xlnx,fpga-xc7v-selectmap", }, // Virtex-7
+	{},
+};
+MODULE_DEVICE_TABLE(of, xlnx_selectmap_of_match);
+
+static struct platform_driver xilinx_selectmap_driver = {
+	.driver = {
+		.name = "xilinx-selectmap",
+		.of_match_table = xlnx_selectmap_of_match,
+	},
+	.probe  = xilinx_selectmap_probe,
+};
+
+module_platform_driver(xilinx_selectmap_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Charles Perry <charles.perry@savoirfairelinux.com>");
+MODULE_DESCRIPTION("Load Xilinx FPGA firmware over SelectMap");