1// SPDX-License-Identifier: GPL-2.0
2/*
3 * FPGA Freeze Bridge Controller
4 *
5 * Copyright (C) 2016 Altera Corporation. All rights reserved.
6 */
7#include <linux/delay.h>
8#include <linux/io.h>
9#include <linux/kernel.h>
10#include <linux/of_device.h>
11#include <linux/module.h>
12#include <linux/fpga/fpga-bridge.h>
13
14#define FREEZE_CSR_STATUS_OFFSET 0
15#define FREEZE_CSR_CTRL_OFFSET 4
16#define FREEZE_CSR_ILLEGAL_REQ_OFFSET 8
17#define FREEZE_CSR_REG_VERSION 12
18
19#define FREEZE_CSR_SUPPORTED_VERSION 2
20#define FREEZE_CSR_OFFICIAL_VERSION 0xad000003
21
22#define FREEZE_CSR_STATUS_FREEZE_REQ_DONE BIT(0)
23#define FREEZE_CSR_STATUS_UNFREEZE_REQ_DONE BIT(1)
24
25#define FREEZE_CSR_CTRL_FREEZE_REQ BIT(0)
26#define FREEZE_CSR_CTRL_RESET_REQ BIT(1)
27#define FREEZE_CSR_CTRL_UNFREEZE_REQ BIT(2)
28
29#define FREEZE_BRIDGE_NAME "freeze"
30
31struct altera_freeze_br_data {
32 struct device *dev;
33 void __iomem *base_addr;
34 bool enable;
35};
36
37/*
38 * Poll status until status bit is set or we have a timeout.
39 */
40static int altera_freeze_br_req_ack(struct altera_freeze_br_data *priv,
41 u32 timeout, u32 req_ack)
42{
43 struct device *dev = priv->dev;
44 void __iomem *csr_illegal_req_addr = priv->base_addr +
45 FREEZE_CSR_ILLEGAL_REQ_OFFSET;
46 u32 status, illegal, ctrl;
47 int ret = -ETIMEDOUT;
48
49 do {
50 illegal = readl(csr_illegal_req_addr);
51 if (illegal) {
52 dev_err(dev, "illegal request detected 0x%x", illegal);
53
54 writel(1, csr_illegal_req_addr);
55
56 illegal = readl(csr_illegal_req_addr);
57 if (illegal)
58 dev_err(dev, "illegal request not cleared 0x%x",
59 illegal);
60
61 ret = -EINVAL;
62 break;
63 }
64
65 status = readl(priv->base_addr + FREEZE_CSR_STATUS_OFFSET);
66 dev_dbg(dev, "%s %x %x\n", __func__, status, req_ack);
67 status &= req_ack;
68 if (status) {
69 ctrl = readl(priv->base_addr + FREEZE_CSR_CTRL_OFFSET);
70 dev_dbg(dev, "%s request %x acknowledged %x %x\n",
71 __func__, req_ack, status, ctrl);
72 ret = 0;
73 break;
74 }
75
76 udelay(1);
77 } while (timeout--);
78
79 if (ret == -ETIMEDOUT)
80 dev_err(dev, "%s timeout waiting for 0x%x\n",
81 __func__, req_ack);
82
83 return ret;
84}
85
86static int altera_freeze_br_do_freeze(struct altera_freeze_br_data *priv,
87 u32 timeout)
88{
89 struct device *dev = priv->dev;
90 void __iomem *csr_ctrl_addr = priv->base_addr +
91 FREEZE_CSR_CTRL_OFFSET;
92 u32 status;
93 int ret;
94
95 status = readl(priv->base_addr + FREEZE_CSR_STATUS_OFFSET);
96
97 dev_dbg(dev, "%s %d %d\n", __func__, status, readl(csr_ctrl_addr));
98
99 if (status & FREEZE_CSR_STATUS_FREEZE_REQ_DONE) {
100 dev_dbg(dev, "%s bridge already disabled %d\n",
101 __func__, status);
102 return 0;
103 } else if (!(status & FREEZE_CSR_STATUS_UNFREEZE_REQ_DONE)) {
104 dev_err(dev, "%s bridge not enabled %d\n", __func__, status);
105 return -EINVAL;
106 }
107
108 writel(FREEZE_CSR_CTRL_FREEZE_REQ, csr_ctrl_addr);
109
110 ret = altera_freeze_br_req_ack(priv, timeout,
111 FREEZE_CSR_STATUS_FREEZE_REQ_DONE);
112
113 if (ret)
114 writel(0, csr_ctrl_addr);
115 else
116 writel(FREEZE_CSR_CTRL_RESET_REQ, csr_ctrl_addr);
117
118 return ret;
119}
120
121static int altera_freeze_br_do_unfreeze(struct altera_freeze_br_data *priv,
122 u32 timeout)
123{
124 struct device *dev = priv->dev;
125 void __iomem *csr_ctrl_addr = priv->base_addr +
126 FREEZE_CSR_CTRL_OFFSET;
127 u32 status;
128 int ret;
129
130 writel(0, csr_ctrl_addr);
131
132 status = readl(priv->base_addr + FREEZE_CSR_STATUS_OFFSET);
133
134 dev_dbg(dev, "%s %d %d\n", __func__, status, readl(csr_ctrl_addr));
135
136 if (status & FREEZE_CSR_STATUS_UNFREEZE_REQ_DONE) {
137 dev_dbg(dev, "%s bridge already enabled %d\n",
138 __func__, status);
139 return 0;
140 } else if (!(status & FREEZE_CSR_STATUS_FREEZE_REQ_DONE)) {
141 dev_err(dev, "%s bridge not frozen %d\n", __func__, status);
142 return -EINVAL;
143 }
144
145 writel(FREEZE_CSR_CTRL_UNFREEZE_REQ, csr_ctrl_addr);
146
147 ret = altera_freeze_br_req_ack(priv, timeout,
148 FREEZE_CSR_STATUS_UNFREEZE_REQ_DONE);
149
150 status = readl(priv->base_addr + FREEZE_CSR_STATUS_OFFSET);
151
152 dev_dbg(dev, "%s %d %d\n", __func__, status, readl(csr_ctrl_addr));
153
154 writel(0, csr_ctrl_addr);
155
156 return ret;
157}
158
159/*
160 * enable = 1 : allow traffic through the bridge
161 * enable = 0 : disable traffic through the bridge
162 */
163static int altera_freeze_br_enable_set(struct fpga_bridge *bridge,
164 bool enable)
165{
166 struct altera_freeze_br_data *priv = bridge->priv;
167 struct fpga_image_info *info = bridge->info;
168 u32 timeout = 0;
169 int ret;
170
171 if (enable) {
172 if (info)
173 timeout = info->enable_timeout_us;
174
175 ret = altera_freeze_br_do_unfreeze(bridge->priv, timeout);
176 } else {
177 if (info)
178 timeout = info->disable_timeout_us;
179
180 ret = altera_freeze_br_do_freeze(bridge->priv, timeout);
181 }
182
183 if (!ret)
184 priv->enable = enable;
185
186 return ret;
187}
188
189static int altera_freeze_br_enable_show(struct fpga_bridge *bridge)
190{
191 struct altera_freeze_br_data *priv = bridge->priv;
192
193 return priv->enable;
194}
195
196static const struct fpga_bridge_ops altera_freeze_br_br_ops = {
197 .enable_set = altera_freeze_br_enable_set,
198 .enable_show = altera_freeze_br_enable_show,
199};
200
201static const struct of_device_id altera_freeze_br_of_match[] = {
202 { .compatible = "altr,freeze-bridge-controller", },
203 {},
204};
205MODULE_DEVICE_TABLE(of, altera_freeze_br_of_match);
206
207static int altera_freeze_br_probe(struct platform_device *pdev)
208{
209 struct device *dev = &pdev->dev;
210 struct device_node *np = pdev->dev.of_node;
211 void __iomem *base_addr;
212 struct altera_freeze_br_data *priv;
213 struct fpga_bridge *br;
214 struct resource *res;
215 u32 status, revision;
216
217 if (!np)
218 return -ENODEV;
219
220 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
221 base_addr = devm_ioremap_resource(dev, res);
222 if (IS_ERR(base_addr))
223 return PTR_ERR(base_addr);
224
225 revision = readl(base_addr + FREEZE_CSR_REG_VERSION);
226 if ((revision != FREEZE_CSR_SUPPORTED_VERSION) &&
227 (revision != FREEZE_CSR_OFFICIAL_VERSION)) {
228 dev_err(dev,
229 "%s unexpected revision 0x%x != 0x%x != 0x%x\n",
230 __func__, revision, FREEZE_CSR_SUPPORTED_VERSION,
231 FREEZE_CSR_OFFICIAL_VERSION);
232 return -EINVAL;
233 }
234
235 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
236 if (!priv)
237 return -ENOMEM;
238
239 priv->dev = dev;
240
241 status = readl(base_addr + FREEZE_CSR_STATUS_OFFSET);
242 if (status & FREEZE_CSR_STATUS_UNFREEZE_REQ_DONE)
243 priv->enable = 1;
244
245 priv->base_addr = base_addr;
246
247 br = devm_fpga_bridge_create(dev, FREEZE_BRIDGE_NAME,
248 &altera_freeze_br_br_ops, priv);
249 if (!br)
250 return -ENOMEM;
251
252 platform_set_drvdata(pdev, br);
253
254 return fpga_bridge_register(br);
255}
256
257static int altera_freeze_br_remove(struct platform_device *pdev)
258{
259 struct fpga_bridge *br = platform_get_drvdata(pdev);
260
261 fpga_bridge_unregister(br);
262
263 return 0;
264}
265
266static struct platform_driver altera_freeze_br_driver = {
267 .probe = altera_freeze_br_probe,
268 .remove = altera_freeze_br_remove,
269 .driver = {
270 .name = "altera_freeze_br",
271 .of_match_table = of_match_ptr(altera_freeze_br_of_match),
272 },
273};
274
275module_platform_driver(altera_freeze_br_driver);
276
277MODULE_DESCRIPTION("Altera Freeze Bridge");
278MODULE_AUTHOR("Alan Tull <atull@opensource.altera.com>");
279MODULE_LICENSE("GPL v2");
280