drivers/fpga/altera-freeze-bridge.c

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