1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * FPGA to/from HPS Bridge Driver for Altera SoCFPGA Devices
4  *
5  *  Copyright (C) 2013-2016 Altera Corporation, All Rights Reserved.
6  *
7  * Includes this patch from the mailing list:
8  *   fpga: altera-hps2fpga: fix HPS2FPGA bridge visibility to L3 masters
9  *   Signed-off-by: Anatolij Gustschin <agust@denx.de>
10  */
11 
12 /*
13  * This driver manages bridges on a Altera SOCFPGA between the ARM host
14  * processor system (HPS) and the embedded FPGA.
15  *
16  * This driver supports enabling and disabling of the configured ports, which
17  * allows for safe reprogramming of the FPGA, assuming that the new FPGA image
18  * uses the same port configuration.  Bridges must be disabled before
19  * reprogramming the FPGA and re-enabled after the FPGA has been programmed.
20  */
21 
22 #include <linux/clk.h>
23 #include <linux/fpga/fpga-bridge.h>
24 #include <linux/kernel.h>
25 #include <linux/mfd/syscon.h>
26 #include <linux/module.h>
27 #include <linux/of_platform.h>
28 #include <linux/regmap.h>
29 #include <linux/reset.h>
30 #include <linux/spinlock.h>
31 
32 #define ALT_L3_REMAP_OFST			0x0
33 #define ALT_L3_REMAP_MPUZERO_MSK		0x00000001
34 #define ALT_L3_REMAP_H2F_MSK			0x00000008
35 #define ALT_L3_REMAP_LWH2F_MSK			0x00000010
36 
37 #define HPS2FPGA_BRIDGE_NAME			"hps2fpga"
38 #define LWHPS2FPGA_BRIDGE_NAME			"lwhps2fpga"
39 #define FPGA2HPS_BRIDGE_NAME			"fpga2hps"
40 
41 struct altera_hps2fpga_data {
42 	const char *name;
43 	struct reset_control *bridge_reset;
44 	struct regmap *l3reg;
45 	unsigned int remap_mask;
46 	struct clk *clk;
47 };
48 
49 static int alt_hps2fpga_enable_show(struct fpga_bridge *bridge)
50 {
51 	struct altera_hps2fpga_data *priv = bridge->priv;
52 
53 	return reset_control_status(priv->bridge_reset);
54 }
55 
56 /* The L3 REMAP register is write only, so keep a cached value. */
57 static unsigned int l3_remap_shadow;
58 static DEFINE_SPINLOCK(l3_remap_lock);
59 
60 static int _alt_hps2fpga_enable_set(struct altera_hps2fpga_data *priv,
61 				    bool enable)
62 {
63 	unsigned long flags;
64 	int ret;
65 
66 	/* bring bridge out of reset */
67 	if (enable)
68 		ret = reset_control_deassert(priv->bridge_reset);
69 	else
70 		ret = reset_control_assert(priv->bridge_reset);
71 	if (ret)
72 		return ret;
73 
74 	/* Allow bridge to be visible to L3 masters or not */
75 	if (priv->remap_mask) {
76 		spin_lock_irqsave(&l3_remap_lock, flags);
77 		l3_remap_shadow |= ALT_L3_REMAP_MPUZERO_MSK;
78 
79 		if (enable)
80 			l3_remap_shadow |= priv->remap_mask;
81 		else
82 			l3_remap_shadow &= ~priv->remap_mask;
83 
84 		ret = regmap_write(priv->l3reg, ALT_L3_REMAP_OFST,
85 				   l3_remap_shadow);
86 		spin_unlock_irqrestore(&l3_remap_lock, flags);
87 	}
88 
89 	return ret;
90 }
91 
92 static int alt_hps2fpga_enable_set(struct fpga_bridge *bridge, bool enable)
93 {
94 	return _alt_hps2fpga_enable_set(bridge->priv, enable);
95 }
96 
97 static const struct fpga_bridge_ops altera_hps2fpga_br_ops = {
98 	.enable_set = alt_hps2fpga_enable_set,
99 	.enable_show = alt_hps2fpga_enable_show,
100 };
101 
102 static struct altera_hps2fpga_data hps2fpga_data  = {
103 	.name = HPS2FPGA_BRIDGE_NAME,
104 	.remap_mask = ALT_L3_REMAP_H2F_MSK,
105 };
106 
107 static struct altera_hps2fpga_data lwhps2fpga_data  = {
108 	.name = LWHPS2FPGA_BRIDGE_NAME,
109 	.remap_mask = ALT_L3_REMAP_LWH2F_MSK,
110 };
111 
112 static struct altera_hps2fpga_data fpga2hps_data  = {
113 	.name = FPGA2HPS_BRIDGE_NAME,
114 };
115 
116 static const struct of_device_id altera_fpga_of_match[] = {
117 	{ .compatible = "altr,socfpga-hps2fpga-bridge",
118 	  .data = &hps2fpga_data },
119 	{ .compatible = "altr,socfpga-lwhps2fpga-bridge",
120 	  .data = &lwhps2fpga_data },
121 	{ .compatible = "altr,socfpga-fpga2hps-bridge",
122 	  .data = &fpga2hps_data },
123 	{},
124 };
125 
126 static int alt_fpga_bridge_probe(struct platform_device *pdev)
127 {
128 	struct device *dev = &pdev->dev;
129 	struct altera_hps2fpga_data *priv;
130 	const struct of_device_id *of_id;
131 	struct fpga_bridge *br;
132 	u32 enable;
133 	int ret;
134 
135 	of_id = of_match_device(altera_fpga_of_match, dev);
136 	if (!of_id) {
137 		dev_err(dev, "failed to match device\n");
138 		return -ENODEV;
139 	}
140 
141 	priv = (struct altera_hps2fpga_data *)of_id->data;
142 
143 	priv->bridge_reset = of_reset_control_get_exclusive_by_index(dev->of_node,
144 								     0);
145 	if (IS_ERR(priv->bridge_reset)) {
146 		dev_err(dev, "Could not get %s reset control\n", priv->name);
147 		return PTR_ERR(priv->bridge_reset);
148 	}
149 
150 	if (priv->remap_mask) {
151 		priv->l3reg = syscon_regmap_lookup_by_compatible("altr,l3regs");
152 		if (IS_ERR(priv->l3reg)) {
153 			dev_err(dev, "regmap for altr,l3regs lookup failed\n");
154 			return PTR_ERR(priv->l3reg);
155 		}
156 	}
157 
158 	priv->clk = devm_clk_get(dev, NULL);
159 	if (IS_ERR(priv->clk)) {
160 		dev_err(dev, "no clock specified\n");
161 		return PTR_ERR(priv->clk);
162 	}
163 
164 	ret = clk_prepare_enable(priv->clk);
165 	if (ret) {
166 		dev_err(dev, "could not enable clock\n");
167 		return -EBUSY;
168 	}
169 
170 	if (!of_property_read_u32(dev->of_node, "bridge-enable", &enable)) {
171 		if (enable > 1) {
172 			dev_warn(dev, "invalid bridge-enable %u > 1\n", enable);
173 		} else {
174 			dev_info(dev, "%s bridge\n",
175 				 (enable ? "enabling" : "disabling"));
176 
177 			ret = _alt_hps2fpga_enable_set(priv, enable);
178 			if (ret)
179 				goto err;
180 		}
181 	}
182 
183 	br = fpga_bridge_register(dev, priv->name,
184 				  &altera_hps2fpga_br_ops, priv);
185 	if (IS_ERR(br)) {
186 		ret = PTR_ERR(br);
187 		goto err;
188 	}
189 
190 	platform_set_drvdata(pdev, br);
191 
192 	return 0;
193 
194 err:
195 	clk_disable_unprepare(priv->clk);
196 
197 	return ret;
198 }
199 
200 static int alt_fpga_bridge_remove(struct platform_device *pdev)
201 {
202 	struct fpga_bridge *bridge = platform_get_drvdata(pdev);
203 	struct altera_hps2fpga_data *priv = bridge->priv;
204 
205 	fpga_bridge_unregister(bridge);
206 
207 	clk_disable_unprepare(priv->clk);
208 
209 	return 0;
210 }
211 
212 MODULE_DEVICE_TABLE(of, altera_fpga_of_match);
213 
214 static struct platform_driver alt_fpga_bridge_driver = {
215 	.probe = alt_fpga_bridge_probe,
216 	.remove = alt_fpga_bridge_remove,
217 	.driver = {
218 		.name	= "altera_hps2fpga_bridge",
219 		.of_match_table = of_match_ptr(altera_fpga_of_match),
220 	},
221 };
222 
223 module_platform_driver(alt_fpga_bridge_driver);
224 
225 MODULE_DESCRIPTION("Altera SoCFPGA HPS to FPGA Bridge");
226 MODULE_AUTHOR("Alan Tull <atull@opensource.altera.com>");
227 MODULE_LICENSE("GPL v2");
228