drivers/fpga/altera-hps2fpga.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * FPGA to/from HPS Bridge Driver for Altera SoCFPGA Devices
   4  *
   5  *  Copyright (C) 2013-2016 Altera Corporation, All Rights Reserved.
   6  *
   7  * Includes this patch from the mailing list:
   8  *   fpga: altera-hps2fpga: fix HPS2FPGA bridge visibility to L3 masters
   9  *   Signed-off-by: Anatolij Gustschin <agust@denx.de>
  10  */
  11
  12 /*
  13  * This driver manages bridges on a Altera SOCFPGA between the ARM host
  14  * processor system (HPS) and the embedded FPGA.
  15  *
  16  * This driver supports enabling and disabling of the configured ports, which
  17  * allows for safe reprogramming of the FPGA, assuming that the new FPGA image
  18  * uses the same port configuration.  Bridges must be disabled before
  19  * reprogramming the FPGA and re-enabled after the FPGA has been programmed.
  20  */
  21
  22 #include <linux/clk.h>
  23 #include <linux/fpga/fpga-bridge.h>
  24 #include <linux/kernel.h>
  25 #include <linux/mfd/syscon.h>
  26 #include <linux/module.h>
  27 #include <linux/of.h>
  28 #include <linux/property.h>
  29 #include <linux/regmap.h>
  30 #include <linux/reset.h>
  31 #include <linux/spinlock.h>
  32
  33 #define ALT_L3_REMAP_OFST                       0x0
  34 #define ALT_L3_REMAP_MPUZERO_MSK                0x00000001
  35 #define ALT_L3_REMAP_H2F_MSK                    0x00000008
  36 #define ALT_L3_REMAP_LWH2F_MSK                  0x00000010
  37
  38 #define HPS2FPGA_BRIDGE_NAME                    "hps2fpga"
  39 #define LWHPS2FPGA_BRIDGE_NAME                  "lwhps2fpga"
  40 #define FPGA2HPS_BRIDGE_NAME                    "fpga2hps"
  41
  42 struct altera_hps2fpga_data {
  43         const char *name;
  44         struct reset_control *bridge_reset;
  45         struct regmap *l3reg;
  46         unsigned int remap_mask;
  47         struct clk *clk;
  48 };
  49
  50 static int alt_hps2fpga_enable_show(struct fpga_bridge *bridge)
  51 {
  52         struct altera_hps2fpga_data *priv = bridge->priv;
  53
  54         return reset_control_status(priv->bridge_reset);
  55 }
  56
  57 /* The L3 REMAP register is write only, so keep a cached value. */
  58 static unsigned int l3_remap_shadow;
  59 static DEFINE_SPINLOCK(l3_remap_lock);
  60
  61 static int _alt_hps2fpga_enable_set(struct altera_hps2fpga_data *priv,
  62                                     bool enable)
  63 {
  64         unsigned long flags;
  65         int ret;
  66
  67         /* bring bridge out of reset */
  68         if (enable)
  69                 ret = reset_control_deassert(priv->bridge_reset);
  70         else
  71                 ret = reset_control_assert(priv->bridge_reset);
  72         if (ret)
  73                 return ret;
  74
  75         /* Allow bridge to be visible to L3 masters or not */
  76         if (priv->remap_mask) {
  77                 spin_lock_irqsave(&l3_remap_lock, flags);
  78                 l3_remap_shadow |= ALT_L3_REMAP_MPUZERO_MSK;
  79
  80                 if (enable)
  81                         l3_remap_shadow |= priv->remap_mask;
  82                 else
  83                         l3_remap_shadow &= ~priv->remap_mask;
  84
  85                 ret = regmap_write(priv->l3reg, ALT_L3_REMAP_OFST,
  86                                    l3_remap_shadow);
  87                 spin_unlock_irqrestore(&l3_remap_lock, flags);
  88         }
  89
  90         return ret;
  91 }
  92
  93 static int alt_hps2fpga_enable_set(struct fpga_bridge *bridge, bool enable)
  94 {
  95         return _alt_hps2fpga_enable_set(bridge->priv, enable);
  96 }
  97
  98 static const struct fpga_bridge_ops altera_hps2fpga_br_ops = {
  99         .enable_set = alt_hps2fpga_enable_set,
 100         .enable_show = alt_hps2fpga_enable_show,
 101 };
 102
 103 static struct altera_hps2fpga_data hps2fpga_data  = {
 104         .name = HPS2FPGA_BRIDGE_NAME,
 105         .remap_mask = ALT_L3_REMAP_H2F_MSK,
 106 };
 107
 108 static struct altera_hps2fpga_data lwhps2fpga_data  = {
 109         .name = LWHPS2FPGA_BRIDGE_NAME,
 110         .remap_mask = ALT_L3_REMAP_LWH2F_MSK,
 111 };
 112
 113 static struct altera_hps2fpga_data fpga2hps_data  = {
 114         .name = FPGA2HPS_BRIDGE_NAME,
 115 };
 116
 117 static const struct of_device_id altera_fpga_of_match[] = {
 118         { .compatible = "altr,socfpga-hps2fpga-bridge",
 119           .data = &hps2fpga_data },
 120         { .compatible = "altr,socfpga-lwhps2fpga-bridge",
 121           .data = &lwhps2fpga_data },
 122         { .compatible = "altr,socfpga-fpga2hps-bridge",
 123           .data = &fpga2hps_data },
 124         {},
 125 };
 126
 127 static int alt_fpga_bridge_probe(struct platform_device *pdev)
 128 {
 129         struct device *dev = &pdev->dev;
 130         struct altera_hps2fpga_data *priv;
 131         struct fpga_bridge *br;
 132         u32 enable;
 133         int ret;
 134
 135         priv = (struct altera_hps2fpga_data *)device_get_match_data(dev);
 136
 137         priv->bridge_reset = of_reset_control_get_exclusive_by_index(dev->of_node,
 138                                                                      0);
 139         if (IS_ERR(priv->bridge_reset)) {
 140                 dev_err(dev, "Could not get %s reset control\n", priv->name);
 141                 return PTR_ERR(priv->bridge_reset);
 142         }
 143
 144         if (priv->remap_mask) {
 145                 priv->l3reg = syscon_regmap_lookup_by_compatible("altr,l3regs");
 146                 if (IS_ERR(priv->l3reg)) {
 147                         dev_err(dev, "regmap for altr,l3regs lookup failed\n");
 148                         return PTR_ERR(priv->l3reg);
 149                 }
 150         }
 151
 152         priv->clk = devm_clk_get(dev, NULL);
 153         if (IS_ERR(priv->clk)) {
 154                 dev_err(dev, "no clock specified\n");
 155                 return PTR_ERR(priv->clk);
 156         }
 157
 158         ret = clk_prepare_enable(priv->clk);
 159         if (ret) {
 160                 dev_err(dev, "could not enable clock\n");
 161                 return -EBUSY;
 162         }
 163
 164         if (!of_property_read_u32(dev->of_node, "bridge-enable", &enable)) {
 165                 if (enable > 1) {
 166                         dev_warn(dev, "invalid bridge-enable %u > 1\n", enable);
 167                 } else {
 168                         dev_info(dev, "%s bridge\n",
 169                                  (enable ? "enabling" : "disabling"));
 170
 171                         ret = _alt_hps2fpga_enable_set(priv, enable);
 172                         if (ret)
 173                                 goto err;
 174                 }
 175         }
 176
 177         br = fpga_bridge_register(dev, priv->name,
 178                                   &altera_hps2fpga_br_ops, priv);
 179         if (IS_ERR(br)) {
 180                 ret = PTR_ERR(br);
 181                 goto err;
 182         }
 183
 184         platform_set_drvdata(pdev, br);
 185
 186         return 0;
 187
 188 err:
 189         clk_disable_unprepare(priv->clk);
 190
 191         return ret;
 192 }
 193
 194 static void alt_fpga_bridge_remove(struct platform_device *pdev)
 195 {
 196         struct fpga_bridge *bridge = platform_get_drvdata(pdev);
 197         struct altera_hps2fpga_data *priv = bridge->priv;
 198
 199         fpga_bridge_unregister(bridge);
 200
 201         clk_disable_unprepare(priv->clk);
 202 }
 203
 204 MODULE_DEVICE_TABLE(of, altera_fpga_of_match);
 205
 206 static struct platform_driver alt_fpga_bridge_driver = {
 207         .probe = alt_fpga_bridge_probe,
 208         .remove = alt_fpga_bridge_remove,
 209         .driver = {
 210                 .name   = "altera_hps2fpga_bridge",
 211                 .of_match_table = of_match_ptr(altera_fpga_of_match),
 212         },
 213 };
 214
 215 module_platform_driver(alt_fpga_bridge_driver);
 216
 217 MODULE_DESCRIPTION("Altera SoCFPGA HPS to FPGA Bridge");
 218 MODULE_AUTHOR("Alan Tull <atull@opensource.altera.com>");
 219 MODULE_LICENSE("GPL v2");