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Linux kernel mirror (for testing)
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linux
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.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
50struct alt_fpga2sdram_data {
51 struct device *dev;
52 struct regmap *sdrctl;
53 int mask;
54};
55
56static 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
66static 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
73static int alt_fpga2sdram_enable_set(struct fpga_bridge *bridge, bool enable)
74{
75 return _alt_fpga2sdram_enable_set(bridge->priv, enable);
76}
77
78static const struct fpga_bridge_ops altera_fpga2sdram_br_ops = {
79 .enable_set = alt_fpga2sdram_enable_set,
80 .enable_show = alt_fpga2sdram_enable_show,
81};
82
83static const struct of_device_id altera_fpga_of_match[] = {
84 { .compatible = "altr,socfpga-fpga2sdram-bridge" },
85 {},
86};
87
88static int alt_fpga_bridge_probe(struct platform_device *pdev)
89{
90 struct device *dev = &pdev->dev;
91 struct alt_fpga2sdram_data *priv;
92 struct fpga_bridge *br;
93 u32 enable;
94 struct regmap *sysmgr;
95 int ret = 0;
96
97 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
98 if (!priv)
99 return -ENOMEM;
100
101 priv->dev = dev;
102
103 priv->sdrctl = syscon_regmap_lookup_by_compatible("altr,sdr-ctl");
104 if (IS_ERR(priv->sdrctl)) {
105 dev_err(dev, "regmap for altr,sdr-ctl lookup failed.\n");
106 return PTR_ERR(priv->sdrctl);
107 }
108
109 sysmgr = syscon_regmap_lookup_by_compatible("altr,sys-mgr");
110 if (IS_ERR(sysmgr)) {
111 dev_err(dev, "regmap for altr,sys-mgr lookup failed.\n");
112 return PTR_ERR(sysmgr);
113 }
114
115 /* Get f2s bridge configuration saved in handoff register */
116 regmap_read(sysmgr, SYSMGR_ISWGRP_HANDOFF3, &priv->mask);
117
118 br = fpga_bridge_register(dev, F2S_BRIDGE_NAME,
119 &altera_fpga2sdram_br_ops, priv);
120 if (IS_ERR(br))
121 return PTR_ERR(br);
122
123 platform_set_drvdata(pdev, br);
124
125 dev_info(dev, "driver initialized with handoff %08x\n", priv->mask);
126
127 if (!of_property_read_u32(dev->of_node, "bridge-enable", &enable)) {
128 if (enable > 1) {
129 dev_warn(dev, "invalid bridge-enable %u > 1\n", enable);
130 } else {
131 dev_info(dev, "%s bridge\n",
132 (enable ? "enabling" : "disabling"));
133 ret = _alt_fpga2sdram_enable_set(priv, enable);
134 if (ret) {
135 fpga_bridge_unregister(br);
136 return ret;
137 }
138 }
139 }
140
141 return ret;
142}
143
144static void alt_fpga_bridge_remove(struct platform_device *pdev)
145{
146 struct fpga_bridge *br = platform_get_drvdata(pdev);
147
148 fpga_bridge_unregister(br);
149}
150
151MODULE_DEVICE_TABLE(of, altera_fpga_of_match);
152
153static struct platform_driver altera_fpga_driver = {
154 .probe = alt_fpga_bridge_probe,
155 .remove_new = alt_fpga_bridge_remove,
156 .driver = {
157 .name = "altera_fpga2sdram_bridge",
158 .of_match_table = of_match_ptr(altera_fpga_of_match),
159 },
160};
161
162module_platform_driver(altera_fpga_driver);
163
164MODULE_DESCRIPTION("Altera SoCFPGA FPGA to SDRAM Bridge");
165MODULE_AUTHOR("Alan Tull <atull@opensource.altera.com>");
166MODULE_LICENSE("GPL v2");