drivers/fpga/altera-fpga2sdram.c

   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
  50 struct alt_fpga2sdram_data {
  51         struct device *dev;
  52         struct regmap *sdrctl;
  53         int mask;
  54 };
  55
  56 static 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
  66 static 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
  73 static int alt_fpga2sdram_enable_set(struct fpga_bridge *bridge, bool enable)
  74 {
  75         return _alt_fpga2sdram_enable_set(bridge->priv, enable);
  76 }
  77
  78 static 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
  83 static const struct of_device_id altera_fpga_of_match[] = {
  84         { .compatible = "altr,socfpga-fpga2sdram-bridge" },
  85         {},
  86 };
  87
  88 static 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
 144 static 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
 151 MODULE_DEVICE_TABLE(of, altera_fpga_of_match);
 152
 153 static struct platform_driver altera_fpga_driver = {
 154         .probe = alt_fpga_bridge_probe,
 155         .remove = 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
 162 module_platform_driver(altera_fpga_driver);
 163
 164 MODULE_DESCRIPTION("Altera SoCFPGA FPGA to SDRAM Bridge");
 165 MODULE_AUTHOR("Alan Tull <[email protected]>");
 166 MODULE_LICENSE("GPL v2");