[PATCH v19 11/12] fpga: add altera freeze bridge support

Alan Tull
2016-09-28T18:21:59Z

Add a low level driver for Altera Freeze Bridges to the FPGA Bridge
framework. A freeze bridge is a bridge that exists in the FPGA
fabric to isolate one region of the FPGA from the busses while that
one region is being reprogrammed.

Signed-off-by: Alan Tull <atull@opensource.altera.com>
Signed-off-by: Matthew Gerlach <mgerlach@opensource.altera.com>
---
v19: added in v19 of patchset as it needs for fpga info struct
---
drivers/fpga/Kconfig | 9 ++
drivers/fpga/Makefile | 1 +
drivers/fpga/altera-freeze-bridge.c | 273 ++++++++++++++++++++++++++++++++++++
3 files changed, 283 insertions(+)
create mode 100644 drivers/fpga/altera-freeze-bridge.c

diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
index 55d97d2..0d1887f 100644
--- a/drivers/fpga/Kconfig
+++ b/drivers/fpga/Kconfig
@@ -46,6 +46,15 @@ config SOCFPGA_FPGA_BRIDGE
Say Y to enable drivers for FPGA bridges for Altera SOCFPGA
devices.

+config ALTERA_FREEZE_BRIDGE
+ tristate "Altera FPGA Freeze Bridge"
+ depends on ARCH_SOCFPGA && FPGA_BRIDGE
+ help
+ Say Y to enable drivers for Altera FPGA Freeze bridges. A
+ freeze bridge is a bridge that exists in the FPGA fabric to
+ isolate one region of the FPGA from the busses while that
+ region is being reprogrammed.
+
endif # FPGA

endmenu
diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
index e658436..a6f874d 100644
--- a/drivers/fpga/Makefile
+++ b/drivers/fpga/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_FPGA_MGR_ZYNQ_FPGA) += zynq-fpga.o
# FPGA Bridge Drivers
obj-$(CONFIG_FPGA_BRIDGE) += fpga-bridge.o
obj-$(CONFIG_SOCFPGA_FPGA_BRIDGE) += altera-hps2fpga.o altera-fpga2sdram.o
+obj-$(CONFIG_ALTERA_FREEZE_BRIDGE) += altera-freeze-bridge.o

# High Level Interfaces
obj-$(CONFIG_FPGA_REGION) += fpga-region.o
diff --git a/drivers/fpga/altera-freeze-bridge.c b/drivers/fpga/altera-freeze-bridge.c
new file mode 100644
index 0000000..8dcd9fb
--- /dev/null
+++ b/drivers/fpga/altera-freeze-bridge.c
@@ -0,0 +1,273 @@
+/*
+ * 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");
--
2.9.3