MIPS: lantiq: Convert the fpi bus driver to a platform_driver

Instead of hacking the configuration of the FPI bus into the arch code
add an own bus driver for this internal bus. The FPI bus is the main
bus of the SoC. This bus driver makes sure the bus is configured
correctly before the child drivers are getting initialized. This driver
will probably also be used on different SoCs later.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: john@phrozen.org
Cc: p.zabel@pengutronix.de
Cc: kishon@ti.com
Cc: mark.rutland@arm.com
Cc: linux-mips@linux-mips.org
Cc: linux-mtd@lists.infradead.org
Cc: linux-watchdog@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: linux-spi@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/17122/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 88 insertions, 0 deletions

diff --git a/drivers/soc/lantiq/Makefile b/drivers/soc/lantiq/Makefile
new file mode 100644
index 000000000000..35aa86bd1023
--- /dev/null
+++ b/drivers/soc/lantiq/Makefile
@@ -0,0 +1 @@
+obj-y				+= fpi-bus.o
diff --git a/drivers/soc/lantiq/fpi-bus.c b/drivers/soc/lantiq/fpi-bus.c
new file mode 100644
index 000000000000..a671c9984c4c
--- /dev/null
+++ b/drivers/soc/lantiq/fpi-bus.c
@@ -0,0 +1,87 @@
+/*
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License version 2 as published
+ *  by the Free Software Foundation.
+ *
+ *  Copyright (C) 2011-2015 John Crispin <blogic@phrozen.org>
+ *  Copyright (C) 2015 Martin Blumenstingl <martin.blumenstingl@googlemail.com>
+ *  Copyright (C) 2017 Hauke Mehrtens <hauke@hauke-m.de>
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+
+#include <lantiq_soc.h>
+
+#define XBAR_ALWAYS_LAST	0x430
+#define XBAR_FPI_BURST_EN	BIT(1)
+#define XBAR_AHB_BURST_EN	BIT(2)
+
+#define RCU_VR9_BE_AHB1S	0x00000008
+
+static int ltq_fpi_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct resource *res_xbar;
+	struct regmap *rcu_regmap;
+	void __iomem *xbar_membase;
+	u32 rcu_ahb_endianness_reg_offset;
+	int ret;
+
+	res_xbar = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	xbar_membase = devm_ioremap_resource(dev, res_xbar);
+	if (IS_ERR(xbar_membase))
+		return PTR_ERR(xbar_membase);
+
+	/* RCU configuration is optional */
+	rcu_regmap = syscon_regmap_lookup_by_phandle(np, "lantiq,rcu");
+	if (IS_ERR(rcu_regmap))
+		return PTR_ERR(rcu_regmap);
+
+	ret = device_property_read_u32(dev, "lantiq,offset-endianness",
+				       &rcu_ahb_endianness_reg_offset);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to get RCU reg offset\n");
+		return ret;
+	}
+
+	ret = regmap_update_bits(rcu_regmap, rcu_ahb_endianness_reg_offset,
+				 RCU_VR9_BE_AHB1S, RCU_VR9_BE_AHB1S);
+	if (ret) {
+		dev_warn(&pdev->dev,
+			 "Failed to configure RCU AHB endianness\n");
+		return ret;
+	}
+
+	/* disable fpi burst */
+	ltq_w32_mask(XBAR_FPI_BURST_EN, 0, xbar_membase + XBAR_ALWAYS_LAST);
+
+	return of_platform_populate(dev->of_node, NULL, NULL, dev);
+}
+
+static const struct of_device_id ltq_fpi_match[] = {
+	{ .compatible = "lantiq,xrx200-fpi" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, ltq_fpi_match);
+
+static struct platform_driver ltq_fpi_driver = {
+	.probe = ltq_fpi_probe,
+	.driver = {
+		.name = "fpi-xway",
+		.of_match_table = ltq_fpi_match,
+	},
+};
+
+module_platform_driver(ltq_fpi_driver);
+
+MODULE_DESCRIPTION("Lantiq FPI bus driver");
+MODULE_LICENSE("GPL");