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/*
* FPGA Freeze Bridge Controller
*
* Copyright (C) 2016 Altera Corporation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/of_device.h>
#include <linux/module.h>
#include <linux/fpga/fpga-bridge.h>
#define FREEZE_CSR_STATUS_OFFSET 0
#define FREEZE_CSR_CTRL_OFFSET 4
#define FREEZE_CSR_ILLEGAL_REQ_OFFSET 8
#define FREEZE_CSR_REG_VERSION 12
#define FREEZE_CSR_SUPPORTED_VERSION 2
#define FREEZE_CSR_STATUS_FREEZE_REQ_DONE BIT(0)
#define FREEZE_CSR_STATUS_UNFREEZE_REQ_DONE BIT(1)
#define FREEZE_CSR_CTRL_FREEZE_REQ BIT(0)
#define FREEZE_CSR_CTRL_RESET_REQ BIT(1)
#define FREEZE_CSR_CTRL_UNFREEZE_REQ BIT(2)
#define FREEZE_BRIDGE_NAME "freeze"
struct altera_freeze_br_data {
struct device *dev;
void __iomem *base_addr;
bool enable;
};
/*
* Poll status until status bit is set or we have a timeout.
*/
static int altera_freeze_br_req_ack(struct altera_freeze_br_data *priv,
u32 timeout, u32 req_ack)
{
struct device *dev = priv->dev;
void __iomem *csr_illegal_req_addr = priv->base_addr +
FREEZE_CSR_ILLEGAL_REQ_OFFSET;
u32 status, illegal, ctrl;
int ret = -ETIMEDOUT;
do {
illegal = readl(csr_illegal_req_addr);
if (illegal) {
dev_err(dev, "illegal request detected 0x%x", illegal);
writel(1, csr_illegal_req_addr);
illegal = readl(csr_illegal_req_addr);
if (illegal)
dev_err(dev, "illegal request not cleared 0x%x",
illegal);
ret = -EINVAL;
break;
}
status = readl(priv->base_addr + FREEZE_CSR_STATUS_OFFSET);
dev_dbg(dev, "%s %x %x\n", __func__, status, req_ack);
status &= req_ack;
if (status) {
ctrl = readl(priv->base_addr + FREEZE_CSR_CTRL_OFFSET);
dev_dbg(dev, "%s request %x acknowledged %x %x\n",
__func__, req_ack, status, ctrl);
ret = 0;
break;
}
udelay(1);
} while (timeout--);
if (ret == -ETIMEDOUT)
dev_err(dev, "%s timeout waiting for 0x%x\n",
__func__, req_ack);
return ret;
}
static int altera_freeze_br_do_freeze(struct altera_freeze_br_data *priv,
u32 timeout)
{
struct device *dev = priv->dev;
void __iomem *csr_ctrl_addr = priv->base_addr +
FREEZE_CSR_CTRL_OFFSET;
u32 status;
int ret;
status = readl(priv->base_addr + FREEZE_CSR_STATUS_OFFSET);
dev_dbg(dev, "%s %d %d\n", __func__, status, readl(csr_ctrl_addr));
if (status & FREEZE_CSR_STATUS_FREEZE_REQ_DONE) {
dev_dbg(dev, "%s bridge already disabled %d\n",
__func__, status);
return 0;
} else if (!(status & FREEZE_CSR_STATUS_UNFREEZE_REQ_DONE)) {
dev_err(dev, "%s bridge not enabled %d\n", __func__, status);
return -EINVAL;
}
writel(FREEZE_CSR_CTRL_FREEZE_REQ, csr_ctrl_addr);
ret = altera_freeze_br_req_ack(priv, timeout,
FREEZE_CSR_STATUS_FREEZE_REQ_DONE);
if (ret)
writel(0, csr_ctrl_addr);
else
writel(FREEZE_CSR_CTRL_RESET_REQ, csr_ctrl_addr);
return ret;
}
static int altera_freeze_br_do_unfreeze(struct altera_freeze_br_data *priv,
u32 timeout)
{
struct device *dev = priv->dev;
void __iomem *csr_ctrl_addr = priv->base_addr +
FREEZE_CSR_CTRL_OFFSET;
u32 status;
int ret;
writel(0, csr_ctrl_addr);
status = readl(priv->base_addr + FREEZE_CSR_STATUS_OFFSET);
dev_dbg(dev, "%s %d %d\n", __func__, status, readl(csr_ctrl_addr));
if (status & FREEZE_CSR_STATUS_UNFREEZE_REQ_DONE) {
dev_dbg(dev, "%s bridge already enabled %d\n",
__func__, status);
return 0;
} else if (!(status & FREEZE_CSR_STATUS_FREEZE_REQ_DONE)) {
dev_err(dev, "%s bridge not frozen %d\n", __func__, status);
return -EINVAL;
}
writel(FREEZE_CSR_CTRL_UNFREEZE_REQ, csr_ctrl_addr);
ret = altera_freeze_br_req_ack(priv, timeout,
FREEZE_CSR_STATUS_UNFREEZE_REQ_DONE);
status = readl(priv->base_addr + FREEZE_CSR_STATUS_OFFSET);
dev_dbg(dev, "%s %d %d\n", __func__, status, readl(csr_ctrl_addr));
writel(0, csr_ctrl_addr);
return ret;
}
/*
* enable = 1 : allow traffic through the bridge
* enable = 0 : disable traffic through the bridge
*/
static int altera_freeze_br_enable_set(struct fpga_bridge *bridge,
bool enable)
{
struct altera_freeze_br_data *priv = bridge->priv;
struct fpga_image_info *info = bridge->info;
u32 timeout = 0;
int ret;
if (enable) {
if (info)
timeout = info->enable_timeout_us;
ret = altera_freeze_br_do_unfreeze(bridge->priv, timeout);
} else {
if (info)
timeout = info->disable_timeout_us;
ret = altera_freeze_br_do_freeze(bridge->priv, timeout);
}
if (!ret)
priv->enable = enable;
return ret;
}
static int altera_freeze_br_enable_show(struct fpga_bridge *bridge)
{
struct altera_freeze_br_data *priv = bridge->priv;
return priv->enable;
}
static struct fpga_bridge_ops altera_freeze_br_br_ops = {
.enable_set = altera_freeze_br_enable_set,
.enable_show = altera_freeze_br_enable_show,
};
static const struct of_device_id altera_freeze_br_of_match[] = {
{ .compatible = "altr,freeze-bridge-controller", },
{},
};
MODULE_DEVICE_TABLE(of, altera_freeze_br_of_match);
static int altera_freeze_br_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct device_node *np = pdev->dev.of_node;
struct altera_freeze_br_data *priv;
struct resource *res;
u32 status, revision;
if (!np)
return -ENODEV;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->dev = dev;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
priv->base_addr = devm_ioremap_resource(dev, res);
if (IS_ERR(priv->base_addr))
return PTR_ERR(priv->base_addr);
status = readl(priv->base_addr + FREEZE_CSR_STATUS_OFFSET);
if (status & FREEZE_CSR_STATUS_UNFREEZE_REQ_DONE)
priv->enable = 1;
revision = readl(priv->base_addr + FREEZE_CSR_REG_VERSION);
if (revision != FREEZE_CSR_SUPPORTED_VERSION)
dev_warn(dev,
"%s Freeze Controller unexpected revision %d != %d\n",
__func__, revision, FREEZE_CSR_SUPPORTED_VERSION);
return fpga_bridge_register(dev, FREEZE_BRIDGE_NAME,
&altera_freeze_br_br_ops, priv);
}
static int altera_freeze_br_remove(struct platform_device *pdev)
{
fpga_bridge_unregister(&pdev->dev);
return 0;
}
static struct platform_driver altera_freeze_br_driver = {
.probe = altera_freeze_br_probe,
.remove = altera_freeze_br_remove,
.driver = {
.name = "altera_freeze_br",
.of_match_table = of_match_ptr(altera_freeze_br_of_match),
},
};
module_platform_driver(altera_freeze_br_driver);
MODULE_DESCRIPTION("Altera Freeze Bridge");
MODULE_AUTHOR("Alan Tull <atull@opensource.altera.com>");
MODULE_LICENSE("GPL v2");
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