1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * FPGA to SDRAM Bridge Driver for Altera SoCFPGA Devices
4 *
5 * Copyright (C) 2013-2016 Altera Corporation, All Rights Reserved.
6 */
7
8 /*
9 * This driver manages a bridge between an FPGA and the SDRAM used by the ARM
10 * host processor system (HPS).
11 *
12 * The bridge contains 4 read ports, 4 write ports, and 6 command ports.
13 * Reconfiguring these ports requires that no SDRAM transactions occur during
14 * reconfiguration. The code reconfiguring the ports cannot run out of SDRAM
15 * nor can the FPGA access the SDRAM during reconfiguration. This driver does
16 * not support reconfiguring the ports. The ports are configured by code
17 * running out of on chip ram before Linux is started and the configuration
18 * is passed in a handoff register in the system manager.
19 *
20 * This driver supports enabling and disabling of the configured ports, which
21 * allows for safe reprogramming of the FPGA, assuming that the new FPGA image
22 * uses the same port configuration. Bridges must be disabled before
23 * reprogramming the FPGA and re-enabled after the FPGA has been programmed.
24 */
25
26 #include <linux/fpga/fpga-bridge.h>
27 #include <linux/kernel.h>
28 #include <linux/mfd/syscon.h>
29 #include <linux/module.h>
30 #include <linux/of_platform.h>
31 #include <linux/regmap.h>
32
33 #define ALT_SDR_CTL_FPGAPORTRST_OFST 0x80
34 #define ALT_SDR_CTL_FPGAPORTRST_PORTRSTN_MSK 0x00003fff
35 #define ALT_SDR_CTL_FPGAPORTRST_RD_SHIFT 0
36 #define ALT_SDR_CTL_FPGAPORTRST_WR_SHIFT 4
37 #define ALT_SDR_CTL_FPGAPORTRST_CTRL_SHIFT 8
38
39 /*
40 * From the Cyclone V HPS Memory Map document:
41 * These registers are used to store handoff information between the
42 * preloader and the OS. These 8 registers can be used to store any
43 * information. The contents of these registers have no impact on
44 * the state of the HPS hardware.
45 */
46 #define SYSMGR_ISWGRP_HANDOFF3 (0x8C)
47
48 #define F2S_BRIDGE_NAME "fpga2sdram"
49
50 struct alt_fpga2sdram_data {
51 struct device *dev;
52 struct regmap *sdrctl;
53 int mask;
54 };
55
alt_fpga2sdram_enable_show(struct fpga_bridge * bridge)56 static int alt_fpga2sdram_enable_show(struct fpga_bridge *bridge)
57 {
58 struct alt_fpga2sdram_data *priv = bridge->priv;
59 int value;
60
61 regmap_read(priv->sdrctl, ALT_SDR_CTL_FPGAPORTRST_OFST, &value);
62
63 return (value & priv->mask) == priv->mask;
64 }
65
_alt_fpga2sdram_enable_set(struct alt_fpga2sdram_data * priv,bool enable)66 static inline int _alt_fpga2sdram_enable_set(struct alt_fpga2sdram_data *priv,
67 bool enable)
68 {
69 return regmap_update_bits(priv->sdrctl, ALT_SDR_CTL_FPGAPORTRST_OFST,
70 priv->mask, enable ? priv->mask : 0);
71 }
72
alt_fpga2sdram_enable_set(struct fpga_bridge * bridge,bool enable)73 static int alt_fpga2sdram_enable_set(struct fpga_bridge *bridge, bool enable)
74 {
75 return _alt_fpga2sdram_enable_set(bridge->priv, enable);
76 }
77
78 struct prop_map {
79 char *prop_name;
80 u32 *prop_value;
81 u32 prop_max;
82 };
83
84 static const struct fpga_bridge_ops altera_fpga2sdram_br_ops = {
85 .enable_set = alt_fpga2sdram_enable_set,
86 .enable_show = alt_fpga2sdram_enable_show,
87 };
88
89 static const struct of_device_id altera_fpga_of_match[] = {
90 { .compatible = "altr,socfpga-fpga2sdram-bridge" },
91 {},
92 };
93
alt_fpga_bridge_probe(struct platform_device * pdev)94 static int alt_fpga_bridge_probe(struct platform_device *pdev)
95 {
96 struct device *dev = &pdev->dev;
97 struct alt_fpga2sdram_data *priv;
98 struct fpga_bridge *br;
99 u32 enable;
100 struct regmap *sysmgr;
101 int ret = 0;
102
103 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
104 if (!priv)
105 return -ENOMEM;
106
107 priv->dev = dev;
108
109 priv->sdrctl = syscon_regmap_lookup_by_compatible("altr,sdr-ctl");
110 if (IS_ERR(priv->sdrctl)) {
111 dev_err(dev, "regmap for altr,sdr-ctl lookup failed.\n");
112 return PTR_ERR(priv->sdrctl);
113 }
114
115 sysmgr = syscon_regmap_lookup_by_compatible("altr,sys-mgr");
116 if (IS_ERR(sysmgr)) {
117 dev_err(dev, "regmap for altr,sys-mgr lookup failed.\n");
118 return PTR_ERR(sysmgr);
119 }
120
121 /* Get f2s bridge configuration saved in handoff register */
122 regmap_read(sysmgr, SYSMGR_ISWGRP_HANDOFF3, &priv->mask);
123
124 br = fpga_bridge_register(dev, F2S_BRIDGE_NAME,
125 &altera_fpga2sdram_br_ops, priv);
126 if (IS_ERR(br))
127 return PTR_ERR(br);
128
129 platform_set_drvdata(pdev, br);
130
131 dev_info(dev, "driver initialized with handoff %08x\n", priv->mask);
132
133 if (!of_property_read_u32(dev->of_node, "bridge-enable", &enable)) {
134 if (enable > 1) {
135 dev_warn(dev, "invalid bridge-enable %u > 1\n", enable);
136 } else {
137 dev_info(dev, "%s bridge\n",
138 (enable ? "enabling" : "disabling"));
139 ret = _alt_fpga2sdram_enable_set(priv, enable);
140 if (ret) {
141 fpga_bridge_unregister(br);
142 return ret;
143 }
144 }
145 }
146
147 return ret;
148 }
149
alt_fpga_bridge_remove(struct platform_device * pdev)150 static int alt_fpga_bridge_remove(struct platform_device *pdev)
151 {
152 struct fpga_bridge *br = platform_get_drvdata(pdev);
153
154 fpga_bridge_unregister(br);
155
156 return 0;
157 }
158
159 MODULE_DEVICE_TABLE(of, altera_fpga_of_match);
160
161 static struct platform_driver altera_fpga_driver = {
162 .probe = alt_fpga_bridge_probe,
163 .remove = alt_fpga_bridge_remove,
164 .driver = {
165 .name = "altera_fpga2sdram_bridge",
166 .of_match_table = of_match_ptr(altera_fpga_of_match),
167 },
168 };
169
170 module_platform_driver(altera_fpga_driver);
171
172 MODULE_DESCRIPTION("Altera SoCFPGA FPGA to SDRAM Bridge");
173 MODULE_AUTHOR("Alan Tull <atull@opensource.altera.com>");
174 MODULE_LICENSE("GPL v2");
175