// SPDX-License-Identifier: GPL-2.0
/*
* FPGA to SDRAM Bridge Driver for Altera SoCFPGA Devices
*
* Copyright (C) 2013-2016 Altera Corporation, All Rights Reserved.
*/
/*
* This driver manages a bridge between an FPGA and the SDRAM used by the ARM
* host processor system (HPS).
*
* The bridge contains 4 read ports, 4 write ports, and 6 command ports.
* Reconfiguring these ports requires that no SDRAM transactions occur during
* reconfiguration. The code reconfiguring the ports cannot run out of SDRAM
* nor can the FPGA access the SDRAM during reconfiguration. This driver does
* not support reconfiguring the ports. The ports are configured by code
* running out of on chip ram before Linux is started and the configuration
* is passed in a handoff register in the system manager.
*
* This driver supports enabling and disabling of the configured ports, which
* allows for safe reprogramming of the FPGA, assuming that the new FPGA image
* uses the same port configuration. Bridges must be disabled before
* reprogramming the FPGA and re-enabled after the FPGA has been programmed.
*/
#include <linux/fpga/fpga-bridge.h>
#include <linux/kernel.h>
#include <linux/mfd/syscon.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/regmap.h>
#define ALT_SDR_CTL_FPGAPORTRST_OFST 0x80
#define ALT_SDR_CTL_FPGAPORTRST_PORTRSTN_MSK 0x00003fff
#define ALT_SDR_CTL_FPGAPORTRST_RD_SHIFT 0
#define ALT_SDR_CTL_FPGAPORTRST_WR_SHIFT 4
#define ALT_SDR_CTL_FPGAPORTRST_CTRL_SHIFT 8
/*
* From the Cyclone V HPS Memory Map document:
* These registers are used to store handoff information between the
* preloader and the OS. These 8 registers can be used to store any
* information. The contents of these registers have no impact on
* the state of the HPS hardware.
*/
#define SYSMGR_ISWGRP_HANDOFF3 (0x8C)
#define F2S_BRIDGE_NAME "fpga2sdram"
struct alt_fpga2sdram_data {
struct device *dev;
struct regmap *sdrctl;
int mask;
};
static int alt_fpga2sdram_enable_show(struct fpga_bridge *bridge)
{
struct alt_fpga2sdram_data *priv = bridge->priv;
int value;
regmap_read(priv->sdrctl, ALT_SDR_CTL_FPGAPORTRST_OFST, &value);
return (value & priv->mask) == priv->mask;
}
static inline int _alt_fpga2sdram_enable_set(struct alt_fpga2sdram_data *priv,
bool enable)
{
return regmap_update_bits(priv->sdrctl, ALT_SDR_CTL_FPGAPORTRST_OFST,
priv->mask, enable ? priv->mask : 0);
}
static int alt_fpga2sdram_enable_set(struct fpga_bridge *bridge, bool enable)
{
return _alt_fpga2sdram_enable_set(bridge->priv, enable);
}
static const struct fpga_bridge_ops altera_fpga2sdram_br_ops = {
.enable_set = alt_fpga2sdram_enable_set,
.enable_show = alt_fpga2sdram_enable_show,
};
static const struct of_device_id altera_fpga_of_match[] = {
{ .compatible = "altr,socfpga-fpga2sdram-bridge" },
{},
};
static int alt_fpga_bridge_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct alt_fpga2sdram_data *priv;
struct fpga_bridge *br;
u32 enable;
struct regmap *sysmgr;
int ret = 0;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->dev = dev;
priv->sdrctl = syscon_regmap_lookup_by_compatible("altr,sdr-ctl");
if (IS_ERR(priv->sdrctl)) {
dev_err(dev, "regmap for altr,sdr-ctl lookup failed.\n");
return PTR_ERR(priv->sdrctl);
}
sysmgr = syscon_regmap_lookup_by_compatible("altr,sys-mgr");
if (IS_ERR(sysmgr)) {
dev_err(dev, "regmap for altr,sys-mgr lookup failed.\n");
return PTR_ERR(sysmgr);
}
/* Get f2s bridge configuration saved in handoff register */
regmap_read(sysmgr, SYSMGR_ISWGRP_HANDOFF3, &priv->mask);
br = fpga_bridge_register(dev, F2S_BRIDGE_NAME,
&altera_fpga2sdram_br_ops, priv);
if (IS_ERR(br))
return PTR_ERR(br);
platform_set_drvdata(pdev, br);
dev_info(dev, "driver initialized with handoff %08x\n", priv->mask);
if (!of_property_read_u32(dev->of_node, "bridge-enable", &enable)) {
if (enable > 1) {
dev_warn(dev, "invalid bridge-enable %u > 1\n", enable);
} else {
dev_info(dev, "%s bridge\n",
(enable ? "enabling" : "disabling"));
ret = _alt_fpga2sdram_enable_set(priv, enable);
if (ret) {
fpga_bridge_unregister(br);
return ret;
}
}
}
return ret;
}
static void alt_fpga_bridge_remove(struct platform_device *pdev)
{
struct fpga_bridge *br = platform_get_drvdata(pdev);
fpga_bridge_unregister(br);
}
MODULE_DEVICE_TABLE(of, altera_fpga_of_match);
static struct platform_driver altera_fpga_driver = {
.probe = alt_fpga_bridge_probe,
.remove_new = alt_fpga_bridge_remove,
.driver = {
.name = "altera_fpga2sdram_bridge",
.of_match_table = of_match_ptr(altera_fpga_of_match),
},
};
module_platform_driver(altera_fpga_driver);
MODULE_DESCRIPTION("Altera SoCFPGA FPGA to SDRAM Bridge");
MODULE_AUTHOR("Alan Tull <[email protected]>");
MODULE_LICENSE("GPL v2");
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