[PATCH 2/5] misc: zynq: Add afi config driver

[Nava kishore Manne <nava.manne@xilinx.com>]

This patch adds zynq afi config driver. This is useful for
the configuration of the PS-PL interface on zynq platform.

Signed-off-by: Nava kishore Manne <nava.manne@xilinx.com>
---
 drivers/misc/Kconfig    | 11 ++++++
 drivers/misc/Makefile   |  1 +
 drivers/misc/zynq-afi.c | 81 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 93 insertions(+)
 create mode 100644 drivers/misc/zynq-afi.c

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index f532c59bb59b..877b43b3377d 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -445,6 +445,17 @@ config HISI_HIKEY_USB
 	  switching between the dual-role USB-C port and the USB-A host ports
 	  using only one USB controller.
 
+config ZYNQ_AFI
+	tristate "Xilinx ZYNQ AFI support"
+	help
+	  Zynq AFI driver support for writing to the AFI registers
+	  for configuring PS_PL Bus-width. Xilinx Zynq SoC connect
+	  the PS to the programmable logic (PL) through the AXI port.
+	  This AXI port helps to establish the data path between the
+	  PS and PL.In-order to establish the proper communication path
+	  between PS and PL, the AXI port data path should be configured
+	  with the proper Bus-width values
+
 source "drivers/misc/c2port/Kconfig"
 source "drivers/misc/eeprom/Kconfig"
 source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 99b6f15a3c70..e9b03843100f 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -56,3 +56,4 @@ obj-$(CONFIG_HABANA_AI)		+= habanalabs/
 obj-$(CONFIG_UACCE)		+= uacce/
 obj-$(CONFIG_XILINX_SDFEC)	+= xilinx_sdfec.o
 obj-$(CONFIG_HISI_HIKEY_USB)	+= hisi_hikey_usb.o
+obj-$(CONFIG_ZYNQ_AFI)		+= zynq-afi.o
diff --git a/drivers/misc/zynq-afi.c b/drivers/misc/zynq-afi.c
new file mode 100644
index 000000000000..04317d1bdb98
--- /dev/null
+++ b/drivers/misc/zynq-afi.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Xilinx ZYNQ AFI driver.
+ * Copyright (c) 2018-2021 Xilinx Inc.
+ */
+
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+
+/* Registers and special values for doing register-based operations */
+#define AFI_RDCHAN_CTRL_OFFSET	0x00
+#define AFI_WRCHAN_CTRL_OFFSET	0x14
+
+#define AFI_BUSWIDTH_MASK	0x01
+
+/**
+ * struct afi_fpga - AFI register description
+ * @membase:	pointer to register struct
+ * @afi_width:	AFI bus width to be written
+ */
+struct zynq_afi_fpga {
+	void __iomem	*membase;
+	u32		afi_width;
+};
+
+static int zynq_afi_fpga_probe(struct platform_device *pdev)
+{
+	struct zynq_afi_fpga *afi_fpga;
+	struct resource *res;
+	u32 reg_val;
+	u32 val;
+
+	afi_fpga = devm_kzalloc(&pdev->dev, sizeof(*afi_fpga), GFP_KERNEL);
+	if (!afi_fpga)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	afi_fpga->membase = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(afi_fpga->membase))
+		return PTR_ERR(afi_fpga->membase);
+
+	val = device_property_read_u32(&pdev->dev, "xlnx,afi-width",
+				       &afi_fpga->afi_width);
+	if (val) {
+		dev_err(&pdev->dev, "failed to get the afi bus width\n");
+		return -EINVAL;
+	}
+
+	reg_val = readl(afi_fpga->membase + AFI_RDCHAN_CTRL_OFFSET);
+	reg_val &= ~AFI_BUSWIDTH_MASK;
+	writel(reg_val | afi_fpga->afi_width,
+	       afi_fpga->membase + AFI_RDCHAN_CTRL_OFFSET);
+	reg_val = readl(afi_fpga->membase + AFI_WRCHAN_CTRL_OFFSET);
+	reg_val &= ~AFI_BUSWIDTH_MASK;
+	writel(reg_val | afi_fpga->afi_width,
+	       afi_fpga->membase + AFI_WRCHAN_CTRL_OFFSET);
+
+	return 0;
+}
+
+static const struct of_device_id zynq_afi_fpga_ids[] = {
+	{ .compatible = "xlnx,zynq-afi-fpga" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, zynq_afi_fpga_ids);
+
+static struct platform_driver zynq_afi_fpga_driver = {
+	.driver = {
+		.name = "zynq-afi-fpga",
+		.of_match_table = zynq_afi_fpga_ids,
+	},
+	.probe = zynq_afi_fpga_probe,
+};
+module_platform_driver(zynq_afi_fpga_driver);
+
+MODULE_DESCRIPTION("ZYNQ FPGA AFI module");
+MODULE_AUTHOR("Nava kishore Manne <nava.manne@xilinx.com>");
+MODULE_LICENSE("GPL v2");
-- 
2.18.0