1 // SPDX-License-Identifier: GPL-2.0+
2 /* Microchip Sparx5 Switch Reset driver
3  *
4  * Copyright (c) 2020 Microchip Technology Inc. and its subsidiaries.
5  *
6  * The Sparx5 Chip Register Model can be browsed at this location:
7  * https://github.com/microchip-ung/sparx-5_reginfo
8  */
9 #include <linux/mfd/syscon.h>
10 #include <linux/of.h>
11 #include <linux/module.h>
12 #include <linux/platform_device.h>
13 #include <linux/property.h>
14 #include <linux/regmap.h>
15 #include <linux/reset-controller.h>
16 
17 struct reset_props {
18 	u32 protect_reg;
19 	u32 protect_bit;
20 	u32 reset_reg;
21 	u32 reset_bit;
22 };
23 
24 struct mchp_reset_context {
25 	struct regmap *cpu_ctrl;
26 	struct regmap *gcb_ctrl;
27 	struct reset_controller_dev rcdev;
28 	const struct reset_props *props;
29 };
30 
31 static struct regmap_config sparx5_reset_regmap_config = {
32 	.reg_bits	= 32,
33 	.val_bits	= 32,
34 	.reg_stride	= 4,
35 };
36 
37 static int sparx5_switch_reset(struct mchp_reset_context *ctx)
38 {
39 	u32 val;
40 
41 	/* Make sure the core is PROTECTED from reset */
42 	regmap_update_bits(ctx->cpu_ctrl, ctx->props->protect_reg,
43 			   ctx->props->protect_bit, ctx->props->protect_bit);
44 
45 	/* Start soft reset */
46 	regmap_write(ctx->gcb_ctrl, ctx->props->reset_reg,
47 		     ctx->props->reset_bit);
48 
49 	/* Wait for soft reset done */
50 	return regmap_read_poll_timeout(ctx->gcb_ctrl, ctx->props->reset_reg, val,
51 					(val & ctx->props->reset_bit) == 0,
52 					1, 100);
53 }
54 
55 static int sparx5_reset_noop(struct reset_controller_dev *rcdev,
56 			     unsigned long id)
57 {
58 	return 0;
59 }
60 
61 static const struct reset_control_ops sparx5_reset_ops = {
62 	.reset = sparx5_reset_noop,
63 };
64 
65 static int mchp_sparx5_map_syscon(struct platform_device *pdev, char *name,
66 				  struct regmap **target)
67 {
68 	struct device_node *syscon_np;
69 	struct regmap *regmap;
70 	int err;
71 
72 	syscon_np = of_parse_phandle(pdev->dev.of_node, name, 0);
73 	if (!syscon_np)
74 		return -ENODEV;
75 	regmap = syscon_node_to_regmap(syscon_np);
76 	of_node_put(syscon_np);
77 	if (IS_ERR(regmap)) {
78 		err = PTR_ERR(regmap);
79 		dev_err(&pdev->dev, "No '%s' map: %d\n", name, err);
80 		return err;
81 	}
82 	*target = regmap;
83 	return 0;
84 }
85 
86 static int mchp_sparx5_map_io(struct platform_device *pdev, int index,
87 			      struct regmap **target)
88 {
89 	struct resource *res;
90 	struct regmap *map;
91 	void __iomem *mem;
92 
93 	mem = devm_platform_get_and_ioremap_resource(pdev, index, &res);
94 	if (IS_ERR(mem)) {
95 		dev_err(&pdev->dev, "Could not map resource %d\n", index);
96 		return PTR_ERR(mem);
97 	}
98 	sparx5_reset_regmap_config.name = res->name;
99 	map = devm_regmap_init_mmio(&pdev->dev, mem, &sparx5_reset_regmap_config);
100 	if (IS_ERR(map))
101 		return PTR_ERR(map);
102 	*target = map;
103 	return 0;
104 }
105 
106 static int mchp_sparx5_reset_probe(struct platform_device *pdev)
107 {
108 	struct device_node *dn = pdev->dev.of_node;
109 	struct mchp_reset_context *ctx;
110 	int err;
111 
112 	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
113 	if (!ctx)
114 		return -ENOMEM;
115 
116 	err = mchp_sparx5_map_syscon(pdev, "cpu-syscon", &ctx->cpu_ctrl);
117 	if (err)
118 		return err;
119 	err = mchp_sparx5_map_io(pdev, 0, &ctx->gcb_ctrl);
120 	if (err)
121 		return err;
122 
123 	ctx->rcdev.owner = THIS_MODULE;
124 	ctx->rcdev.nr_resets = 1;
125 	ctx->rcdev.ops = &sparx5_reset_ops;
126 	ctx->rcdev.of_node = dn;
127 	ctx->props = device_get_match_data(&pdev->dev);
128 
129 	/* Issue the reset very early, our actual reset callback is a noop. */
130 	err = sparx5_switch_reset(ctx);
131 	if (err)
132 		return err;
133 
134 	return devm_reset_controller_register(&pdev->dev, &ctx->rcdev);
135 }
136 
137 static const struct reset_props reset_props_sparx5 = {
138 	.protect_reg    = 0x84,
139 	.protect_bit    = BIT(10),
140 	.reset_reg      = 0x0,
141 	.reset_bit      = BIT(1),
142 };
143 
144 static const struct reset_props reset_props_lan966x = {
145 	.protect_reg    = 0x88,
146 	.protect_bit    = BIT(5),
147 	.reset_reg      = 0x0,
148 	.reset_bit      = BIT(1),
149 };
150 
151 static const struct of_device_id mchp_sparx5_reset_of_match[] = {
152 	{
153 		.compatible = "microchip,sparx5-switch-reset",
154 		.data = &reset_props_sparx5,
155 	}, {
156 		.compatible = "microchip,lan966x-switch-reset",
157 		.data = &reset_props_lan966x,
158 	},
159 	{ }
160 };
161 
162 static struct platform_driver mchp_sparx5_reset_driver = {
163 	.probe = mchp_sparx5_reset_probe,
164 	.driver = {
165 		.name = "sparx5-switch-reset",
166 		.of_match_table = mchp_sparx5_reset_of_match,
167 	},
168 };
169 
170 static int __init mchp_sparx5_reset_init(void)
171 {
172 	return platform_driver_register(&mchp_sparx5_reset_driver);
173 }
174 
175 /*
176  * Because this is a global reset, keep this postcore_initcall() to issue the
177  * reset as early as possible during the kernel startup.
178  */
179 postcore_initcall(mchp_sparx5_reset_init);
180 
181 MODULE_DESCRIPTION("Microchip Sparx5 switch reset driver");
182 MODULE_AUTHOR("Steen Hegelund <steen.hegelund@microchip.com>");
183