drivers/fpga/altera-freeze-bridge.c

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