Add new functions to manage recovery of configuration parameters and
restart the controller when asserting bus-reset from root-complex (RC).
This feature is only available if bus-reset (PERST#) line is physically
routed between RC and endpoint and the signal from RC affects endpoint.
This feature works as follows.
- This adds a polling thread, that polls and detects the bus-reset signal,
and recovers configuration parameters for endpoint. The polling period
is fixed at EPC_RESTART_POLL_PERIOD_MS.
- After the endpoint controller starts and the user sets configuration
parameters using sysfs or function drivers, once RC asserts bus-reset
and endpoint can receive it, the endpoint controller will also reset
and initialize configuration parameters.
- If the thread detects bus-reset signal, the thread stops the controller,
unbinds it, quickly binds it and restart it. The configuration
paremters are restored to the user's values.
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@xxxxxxxxxxxxx>
---
drivers/pci/endpoint/Kconfig | 9 +++
drivers/pci/endpoint/Makefile | 1 +
drivers/pci/endpoint/pci-epc-restart.c | 114 +++++++++++++++++++++++++++++++++
include/linux/pci-epc.h | 15 +++++
4 files changed, 139 insertions(+)
create mode 100644 drivers/pci/endpoint/pci-epc-restart.c
diff --git a/drivers/pci/endpoint/Kconfig b/drivers/pci/endpoint/Kconfig
index 17bbdc9..016c82a 100644
--- a/drivers/pci/endpoint/Kconfig
+++ b/drivers/pci/endpoint/Kconfig
@@ -28,6 +28,15 @@ config PCI_ENDPOINT_CONFIGFS
configure the endpoint function and used to bind the
function with a endpoint controller.
+config PCI_ENDPOINT_RESTART
+ bool "PCI Endpoint Restart Management Support"
+ depends on PCI_ENDPOINT
+ help
+ Enable restart management functions, which detects bus-reset
+ from root complex, and recover endpoint configuration.
+ This is only available if bus-reset line is physically routed
+ between root complex and endpoint.
+
source "drivers/pci/endpoint/functions/Kconfig"
endmenu
diff --git a/drivers/pci/endpoint/Makefile b/drivers/pci/endpoint/Makefile
index 95b2fe4..7301aea 100644
--- a/drivers/pci/endpoint/Makefile
+++ b/drivers/pci/endpoint/Makefile
@@ -4,5 +4,6 @@
#
obj-$(CONFIG_PCI_ENDPOINT_CONFIGFS) += pci-ep-cfs.o
+obj-$(CONFIG_PCI_ENDPOINT_RESTART) += pci-epc-restart.o
obj-$(CONFIG_PCI_ENDPOINT) += pci-epc-core.o pci-epf-core.o\
pci-epc-mem.o functions/
diff --git a/drivers/pci/endpoint/pci-epc-restart.c b/drivers/pci/endpoint/pci-epc-restart.c
new file mode 100644
index 0000000..ab956be
--- /dev/null
+++ b/drivers/pci/endpoint/pci-epc-restart.c
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0
+/**
+ * PCI Endpoint Controller Restart Management
+ *
+ * Copyright (C) 2019-2020 Socionext Inc.
+ * Author: Kunihiko Hayashi <hayashi.kunihiko@xxxxxxxxxxxxx>
+ */
+
+#include <linux/completion.h>
+#include <linux/delay.h>
+#include <linux/kthread.h>
+#include <linux/pci-epc.h>
+#include <linux/pci-epf.h>
+
+#define EPC_RESTART_POLL_PERIOD_MS 80
+
+static int pci_epc_restart_thread(void *dev_id)
+{
+ struct pci_epc *epc = dev_id;
+ struct pci_epf *epf;
+ int ret = 0;
+
+ dev_info(&epc->dev, "[epc-restart] thread start\n");
+
+ while (!kthread_should_stop()) {
+ if (epc->restart_poll) {
+ /* call polling function */
+ ret = epc->restart_poll(epc->restart_poll_data);
+ if (!ret) {
+ msleep(EPC_RESTART_POLL_PERIOD_MS);
+ continue;
+ } else if (ret < 0) {
+ break;
+ }
+ } else {
+ /* wait for interrupt */
+ ret = wait_for_completion_interruptible(&epc->restart_comp);
+ if (ret <= 0)
+ break;
+ }
+
+ if (!pci_epc_is_started(epc))
+ continue;
+
+ /*
+ * After stop linkup, call unbind() once and call bind() again.
+ * to reload config parameters to the controller.
+ */
+ pci_epc_stop(epc);
+ list_for_each_entry(epf, &epc->pci_epf, list) {
+ pci_epf_unbind(epf);
+ pci_epf_bind(epf);
+ }
+ pci_epc_start(epc);
+
+ dev_info(&epc->dev, "[epc-restart] assert\n");
+ }
+
+ dev_info(&epc->dev, "[epc-restart] thread exit\n");
+
+ return ret;
+}
+
+/**
+ * pci_epc_restart_init() - initialize epc-restart thread
+ * @epc: the EPC device
+ */
+int pci_epc_restart_init(struct pci_epc *epc)
+{
+ init_completion(&epc->restart_comp);
+
+ epc->restart_task = kthread_run(pci_epc_restart_thread, epc,
+ "pci-epc-restart");
+ if (IS_ERR(epc->restart_task))
+ return PTR_ERR(epc->restart_task);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(pci_epc_restart_init);
+
+/**
+ * pci_epc_restart_cleanup() - clean up epc-restart thread
+ * @epc: the EPC device
+ */
+void pci_epc_restart_cleanup(struct pci_epc *epc)
+{
+ if (epc->restart_task)
+ kthread_stop(epc->restart_task);
+}
+EXPORT_SYMBOL_GPL(pci_epc_restart_cleanup);
+
+/**
+ * pci_epc_restart_notify() - notify to epc-restart thread
+ * @epc: the EPC device
+ */
+void pci_epc_restart_notify(struct pci_epc *epc)
+{
+ complete(&epc->restart_comp);
+}
+EXPORT_SYMBOL_GPL(pci_epc_restart_notify);
+
+/**
+ * pci_epc_restart_register_poll_func() - register polling method for restart thread
+ * @epc: the EPC device
+ * @func: polling function
+ * @data: data for polling function
+ */
+void pci_epc_restart_register_poll_func(struct pci_epc *epc, bool (*func)(void *),
+ void *data)
+{
+ epc->restart_poll = func;
+ epc->restart_poll_data = data;
+}
+EXPORT_SYMBOL_GPL(pci_epc_restart_register_poll_func);
diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
index 5808952..45d2592 100644
--- a/include/linux/pci-epc.h
+++ b/include/linux/pci-epc.h
@@ -132,6 +132,10 @@ struct pci_epc_mem {
* @function_num_map: bitmap to manage physical function number
* @notifier: used to notify EPF of any EPC events (like linkup)
* @started: true if this EPC is started
+ * @restart_task: pointer to task for restart thread
+ * @restart_comp: completion object for receiving reset interrupts from RC
+ * @restart_poll: function to poll reset detection from RC
+ * @restart_poll_data: an argument that restart_poll function gets
*/
struct pci_epc {
struct device dev;
@@ -147,6 +151,11 @@ struct pci_epc {
unsigned long function_num_map;
struct atomic_notifier_head notifier;
bool started;
+ /* for epc-restart */
+ struct task_struct *restart_task;
+ struct completion restart_comp;
+ bool (*restart_poll)(void *func);
+ void *restart_poll_data;
};
/**
@@ -254,4 +263,10 @@ void __iomem *pci_epc_mem_alloc_addr(struct pci_epc *epc,
phys_addr_t *phys_addr, size_t size);
void pci_epc_mem_free_addr(struct pci_epc *epc, phys_addr_t phys_addr,
void __iomem *virt_addr, size_t size);
+int pci_epc_restart_init(struct pci_epc *epc);
+void pci_epc_restart_cleanup(struct pci_epc *epc);
+void pci_epc_restart_notify(struct pci_epc *epc);
+void pci_epc_restart_register_poll_func(struct pci_epc *epc,
+ bool (*func)(void *), void *data);
+
#endif /* __LINUX_PCI_EPC_H */
--
2.7.4
