reset: Add Delta TN48M CPLD reset controller

Delta TN48M CPLD exposes resets for the following:
* 88F7040 SoC
* 88F6820 SoC
* 98DX3265 switch MAC-s
* 88E1680 PHY-s
* 88E1512 PHY
* PoE PSE controller

Controller supports only self clearing resets.

Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Robert Marko <robert.marko@sartura.hr>
Link: https://lore.kernel.org/r/20220131133049.77780-5-robert.marko@sartura.hr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/reset/Kconfig

@@ -256,6 +256,19 @@ config RESET_TI_SYSCON
 	  you wish to use the reset framework for such memory-mapped devices,
 	  say Y here. Otherwise, say N.
 
+config RESET_TN48M_CPLD
+	tristate "Delta Networks TN48M switch CPLD reset controller"
+	depends on MFD_TN48M_CPLD || COMPILE_TEST
+	default MFD_TN48M_CPLD
+	help
+	  This enables the reset controller driver for the Delta TN48M CPLD.
+	  It provides reset signals for Armada 7040 and 385 SoC-s, Alleycat 3X
+	  switch MAC-s, Alaska OOB ethernet PHY, Quad Alaska ethernet PHY-s and
+	  Microchip PD69200 PoE PSE controller.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called reset-tn48m.
+
 config RESET_UNIPHIER
 	tristate "Reset controller driver for UniPhier SoCs"
 	depends on ARCH_UNIPHIER || COMPILE_TEST

drivers/reset/Makefile

@@ -33,6 +33,7 @@ obj-$(CONFIG_RESET_STARFIVE_JH7100) += reset-starfive-jh7100.o
 obj-$(CONFIG_RESET_SUNXI) += reset-sunxi.o
 obj-$(CONFIG_RESET_TI_SCI) += reset-ti-sci.o
 obj-$(CONFIG_RESET_TI_SYSCON) += reset-ti-syscon.o
+obj-$(CONFIG_RESET_TN48M_CPLD) += reset-tn48m.o
 obj-$(CONFIG_RESET_UNIPHIER) += reset-uniphier.o
 obj-$(CONFIG_RESET_UNIPHIER_GLUE) += reset-uniphier-glue.o
 obj-$(CONFIG_RESET_ZYNQ) += reset-zynq.o

drivers/reset/reset-tn48m.c

@@ -0,0 +1,128 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Delta TN48M CPLD reset driver
+ *
+ * Copyright (C) 2021 Sartura Ltd.
+ *
+ * Author: Robert Marko <robert.marko@sartura.hr>
+ */
+
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/reset-controller.h>
+
+#include <dt-bindings/reset/delta,tn48m-reset.h>
+
+#define TN48M_RESET_REG		0x10
+
+#define TN48M_RESET_TIMEOUT_US	125000
+#define TN48M_RESET_SLEEP_US	10
+
+struct tn48_reset_map {
+	u8 bit;
+};
+
+struct tn48_reset_data {
+	struct reset_controller_dev rcdev;
+	struct regmap *regmap;
+};
+
+static const struct tn48_reset_map tn48m_resets[] = {
+	[CPU_88F7040_RESET] = {0},
+	[CPU_88F6820_RESET] = {1},
+	[MAC_98DX3265_RESET] = {2},
+	[PHY_88E1680_RESET] = {4},
+	[PHY_88E1512_RESET] = {6},
+	[POE_RESET] = {7},
+};
+
+static inline struct tn48_reset_data *to_tn48_reset_data(
+			struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct tn48_reset_data, rcdev);
+}
+
+static int tn48m_control_reset(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+	struct tn48_reset_data *data = to_tn48_reset_data(rcdev);
+	unsigned int val;
+
+	regmap_update_bits(data->regmap, TN48M_RESET_REG,
+			   BIT(tn48m_resets[id].bit), 0);
+
+	return regmap_read_poll_timeout(data->regmap,
+					TN48M_RESET_REG,
+					val,
+					val & BIT(tn48m_resets[id].bit),
+					TN48M_RESET_SLEEP_US,
+					TN48M_RESET_TIMEOUT_US);
+}
+
+static int tn48m_control_status(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	struct tn48_reset_data *data = to_tn48_reset_data(rcdev);
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(data->regmap, TN48M_RESET_REG, &regval);
+	if (ret < 0)
+		return ret;
+
+	if (BIT(tn48m_resets[id].bit) & regval)
+		return 0;
+	else
+		return 1;
+}
+
+static const struct reset_control_ops tn48_reset_ops = {
+	.reset		= tn48m_control_reset,
+	.status		= tn48m_control_status,
+};
+
+static int tn48m_reset_probe(struct platform_device *pdev)
+{
+	struct tn48_reset_data *data;
+	struct regmap *regmap;
+
+	regmap = dev_get_regmap(pdev->dev.parent, NULL);
+	if (!regmap)
+		return -ENODEV;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->regmap = regmap;
+
+	data->rcdev.owner = THIS_MODULE;
+	data->rcdev.ops = &tn48_reset_ops;
+	data->rcdev.nr_resets = ARRAY_SIZE(tn48m_resets);
+	data->rcdev.of_node = pdev->dev.of_node;
+
+	return devm_reset_controller_register(&pdev->dev, &data->rcdev);
+}
+
+static const struct of_device_id tn48m_reset_of_match[] = {
+	{ .compatible = "delta,tn48m-reset" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, tn48m_reset_of_match);
+
+static struct platform_driver tn48m_reset_driver = {
+	.driver = {
+		.name = "delta-tn48m-reset",
+		.of_match_table = tn48m_reset_of_match,
+	},
+	.probe = tn48m_reset_probe,
+};
+module_platform_driver(tn48m_reset_driver);
+
+MODULE_AUTHOR("Robert Marko <robert.marko@sartura.hr>");
+MODULE_DESCRIPTION("Delta TN48M CPLD reset driver");
+MODULE_LICENSE("GPL");