1 /*
2  * Copyright (c) 2017, National Instruments Corp.
3  * Copyright (c) 2017, Xilix Inc
4  *
5  * FPGA Bridge Driver for the Xilinx LogiCORE Partial Reconfiguration
6  * Decoupler IP Core.
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License as published by
10  * the Free Software Foundation; version 2 of the License.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15  * GNU General Public License for more details.
16  */
17 
18 #include <linux/clk.h>
19 #include <linux/io.h>
20 #include <linux/kernel.h>
21 #include <linux/of_device.h>
22 #include <linux/module.h>
23 #include <linux/fpga/fpga-bridge.h>
24 
25 #define CTRL_CMD_DECOUPLE	BIT(0)
26 #define CTRL_CMD_COUPLE		0
27 #define CTRL_OFFSET		0
28 
29 struct xlnx_pr_decoupler_data {
30 	void __iomem *io_base;
31 	struct clk *clk;
32 };
33 
34 static inline void xlnx_pr_decoupler_write(struct xlnx_pr_decoupler_data *d,
35 					   u32 offset, u32 val)
36 {
37 	writel(val, d->io_base + offset);
38 }
39 
40 static inline u32 xlnx_pr_decouple_read(const struct xlnx_pr_decoupler_data *d,
41 					u32 offset)
42 {
43 	return readl(d->io_base + offset);
44 }
45 
46 static int xlnx_pr_decoupler_enable_set(struct fpga_bridge *bridge, bool enable)
47 {
48 	int err;
49 	struct xlnx_pr_decoupler_data *priv = bridge->priv;
50 
51 	err = clk_enable(priv->clk);
52 	if (err)
53 		return err;
54 
55 	if (enable)
56 		xlnx_pr_decoupler_write(priv, CTRL_OFFSET, CTRL_CMD_COUPLE);
57 	else
58 		xlnx_pr_decoupler_write(priv, CTRL_OFFSET, CTRL_CMD_DECOUPLE);
59 
60 	clk_disable(priv->clk);
61 
62 	return 0;
63 }
64 
65 static int xlnx_pr_decoupler_enable_show(struct fpga_bridge *bridge)
66 {
67 	const struct xlnx_pr_decoupler_data *priv = bridge->priv;
68 	u32 status;
69 	int err;
70 
71 	err = clk_enable(priv->clk);
72 	if (err)
73 		return err;
74 
75 	status = readl(priv->io_base);
76 
77 	clk_disable(priv->clk);
78 
79 	return !status;
80 }
81 
82 static struct fpga_bridge_ops xlnx_pr_decoupler_br_ops = {
83 	.enable_set = xlnx_pr_decoupler_enable_set,
84 	.enable_show = xlnx_pr_decoupler_enable_show,
85 };
86 
87 static const struct of_device_id xlnx_pr_decoupler_of_match[] = {
88 	{ .compatible = "xlnx,pr-decoupler-1.00", },
89 	{ .compatible = "xlnx,pr-decoupler", },
90 	{},
91 };
92 MODULE_DEVICE_TABLE(of, xlnx_pr_decoupler_of_match);
93 
94 static int xlnx_pr_decoupler_probe(struct platform_device *pdev)
95 {
96 	struct xlnx_pr_decoupler_data *priv;
97 	int err;
98 	struct resource *res;
99 
100 	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
101 	if (!priv)
102 		return -ENOMEM;
103 
104 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
105 	priv->io_base = devm_ioremap_resource(&pdev->dev, res);
106 	if (IS_ERR(priv->io_base))
107 		return PTR_ERR(priv->io_base);
108 
109 	priv->clk = devm_clk_get(&pdev->dev, "aclk");
110 	if (IS_ERR(priv->clk)) {
111 		dev_err(&pdev->dev, "input clock not found\n");
112 		return PTR_ERR(priv->clk);
113 	}
114 
115 	err = clk_prepare_enable(priv->clk);
116 	if (err) {
117 		dev_err(&pdev->dev, "unable to enable clock\n");
118 		return err;
119 	}
120 
121 	clk_disable(priv->clk);
122 
123 	err = fpga_bridge_register(&pdev->dev, "Xilinx PR Decoupler",
124 				   &xlnx_pr_decoupler_br_ops, priv);
125 
126 	if (err) {
127 		dev_err(&pdev->dev, "unable to register Xilinx PR Decoupler");
128 		clk_unprepare(priv->clk);
129 		return err;
130 	}
131 
132 	return 0;
133 }
134 
135 static int xlnx_pr_decoupler_remove(struct platform_device *pdev)
136 {
137 	struct fpga_bridge *bridge = platform_get_drvdata(pdev);
138 	struct xlnx_pr_decoupler_data *p = bridge->priv;
139 
140 	fpga_bridge_unregister(&pdev->dev);
141 
142 	clk_unprepare(p->clk);
143 
144 	return 0;
145 }
146 
147 static struct platform_driver xlnx_pr_decoupler_driver = {
148 	.probe = xlnx_pr_decoupler_probe,
149 	.remove = xlnx_pr_decoupler_remove,
150 	.driver = {
151 		.name = "xlnx_pr_decoupler",
152 		.of_match_table = of_match_ptr(xlnx_pr_decoupler_of_match),
153 	},
154 };
155 
156 module_platform_driver(xlnx_pr_decoupler_driver);
157 
158 MODULE_DESCRIPTION("Xilinx Partial Reconfiguration Decoupler");
159 MODULE_AUTHOR("Moritz Fischer <mdf@kernel.org>");
160 MODULE_AUTHOR("Michal Simek <michal.simek@xilinx.com>");
161 MODULE_LICENSE("GPL v2");
162