[PATCH 6/8] Input: psmouse - add support for SMBus companions

Dmitry Torokhov
2017-03-09T22:18:45Z

From: Benjamin Tissoires <benjamin.tissoires@redhat.com>

This provides glue between PS/2 devices that enumerate the RMI4 devices
and Elan touchpads to the RMI4 (or Elan) SMBus driver.

The SMBus devices keep their PS/2 connection alive. If the initialization
process goes too far (psmouse_activate called), the device disconnects
from the I2C bus and stays on the PS/2 bus, that is why we explicitly
disable PS/2 device reporting (by calling psmouse_deactivate) before
trying to register SMBus companion device.

The HID over I2C devices are enumerated through the ACPI DSDT, and
their PS/2 device also exports the InterTouch bit in the extended
capability 0x0C. However, the firmware keeps its I2C connection open
even after going further in the PS/2 initialization. We don't need
to take extra precautions with those device, especially because they
block their PS/2 communication when HID over I2C is used.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
drivers/input/mouse/Kconfig | 4 +
drivers/input/mouse/Makefile | 2 +
drivers/input/mouse/psmouse-base.c | 16 ++-
drivers/input/mouse/psmouse-smbus.c | 280 ++++++++++++++++++++++++++++++++++++
drivers/input/mouse/psmouse.h | 33 +++++
5 files changed, 333 insertions(+), 2 deletions(-)
create mode 100644 drivers/input/mouse/psmouse-smbus.c

diff --git a/drivers/input/mouse/Kconfig b/drivers/input/mouse/Kconfig
index 096abb4ad5cd..87bde8a210c7 100644
--- a/drivers/input/mouse/Kconfig
+++ b/drivers/input/mouse/Kconfig
@@ -171,6 +171,10 @@ config MOUSE_PS2_VMMOUSE

If unsure, say N.

+config MOUSE_PS2_SMBUS
+ bool
+ depends on MOUSE_PS2
+
config MOUSE_SERIAL
tristate "Serial mouse"
select SERIO
diff --git a/drivers/input/mouse/Makefile b/drivers/input/mouse/Makefile
index 6168b134937b..56bf0ad877c6 100644
--- a/drivers/input/mouse/Makefile
+++ b/drivers/input/mouse/Makefile
@@ -39,6 +39,8 @@ psmouse-$(CONFIG_MOUSE_PS2_TOUCHKIT) += touchkit_ps2.o
psmouse-$(CONFIG_MOUSE_PS2_CYPRESS) += cypress_ps2.o
psmouse-$(CONFIG_MOUSE_PS2_VMMOUSE) += vmmouse.o

+psmouse-$(CONFIG_MOUSE_PS2_SMBUS) += psmouse-smbus.o
+
elan_i2c-objs := elan_i2c_core.o
elan_i2c-$(CONFIG_MOUSE_ELAN_I2C_I2C) += elan_i2c_i2c.o
elan_i2c-$(CONFIG_MOUSE_ELAN_I2C_SMBUS) += elan_i2c_smbus.o
diff --git a/drivers/input/mouse/psmouse-base.c b/drivers/input/mouse/psmouse-base.c
index 40f09ce84f14..bdb48b2acc57 100644
--- a/drivers/input/mouse/psmouse-base.c
+++ b/drivers/input/mouse/psmouse-base.c
@@ -1996,16 +1996,27 @@ static int __init psmouse_init(void)
synaptics_module_init();
hgpk_module_init();

+ err = psmouse_smbus_module_init();
+ if (err)
+ return err;
+
kpsmoused_wq = alloc_ordered_workqueue("kpsmoused", 0);
if (!kpsmoused_wq) {
pr_err("failed to create kpsmoused workqueue\n");
- return -ENOMEM;
+ err = -ENOMEM;
+ goto err_smbus_exit;
}

err = serio_register_driver(&psmouse_drv);
if (err)
- destroy_workqueue(kpsmoused_wq);
+ goto err_destroy_wq;

+ return 0;
+
+err_destroy_wq:
+ destroy_workqueue(kpsmoused_wq);
+err_smbus_exit:
+ psmouse_smbus_module_exit();
return err;
}

@@ -2013,6 +2024,7 @@ static void __exit psmouse_exit(void)
{
serio_unregister_driver(&psmouse_drv);
destroy_workqueue(kpsmoused_wq);
+ psmouse_smbus_module_exit();
}

module_init(psmouse_init);
diff --git a/drivers/input/mouse/psmouse-smbus.c b/drivers/input/mouse/psmouse-smbus.c
new file mode 100644
index 000000000000..5bda551b752f
--- /dev/null
+++ b/drivers/input/mouse/psmouse-smbus.c
@@ -0,0 +1,280 @@
+/*
+ * Copyright (c) 2017 Red Hat, Inc
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/libps2.h>
+#include <linux/i2c.h>
+#include <linux/serio.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+#include "psmouse.h"
+
+struct psmouse_smbus_dev {
+ struct psmouse *psmouse;
+ struct i2c_client *client;
+ struct list_head node;
+ unsigned short addr;
+ bool dead;
+};
+
+static LIST_HEAD(psmouse_smbus_list);
+static DEFINE_MUTEX(psmouse_smbus_mutex);
+
+static void psmouse_smbus_check_adapter(struct i2c_adapter *adapter)
+{
+ struct psmouse_smbus_dev *smbdev;
+
+ if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_HOST_NOTIFY))
+ return;
+
+ mutex_lock(&psmouse_smbus_mutex);
+
+ list_for_each_entry(smbdev, &psmouse_smbus_list, node) {
+ if (smbdev->dead)
+ continue;
+
+ if (smbdev->client)
+ continue;
+
+ if (i2c_probe_func_quick_read(adapter, smbdev->addr) < 0)
+ continue;
+
+ /* Device seems to be there, let's try switching over */
+ psmouse_dbg(smbdev->psmouse,
+ "SMBus companion appeared, triggering rescan\n");
+ serio_rescan(smbdev->psmouse->ps2dev.serio);
+ }
+
+ mutex_unlock(&psmouse_smbus_mutex);
+}
+
+static void psmouse_smbus_detach_i2c_client(struct i2c_client *client)
+{
+ struct psmouse_smbus_dev *smbdev;
+
+ mutex_lock(&psmouse_smbus_mutex);
+
+ list_for_each_entry(smbdev, &psmouse_smbus_list, node) {
+ if (smbdev->client == client) {
+ psmouse_dbg(smbdev->psmouse,
+ "Marking SMBus companion %s as gone\n",
+ dev_name(&smbdev->client->dev));
+ smbdev->client = NULL;
+ smbdev->dead = true;
+ serio_rescan(smbdev->psmouse->ps2dev.serio);
+ }
+ }
+
+ mutex_unlock(&psmouse_smbus_mutex);
+}
+
+static int psmouse_smbus_notifier_call(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ struct device *dev = data;
+
+ switch (action) {
+ case BUS_NOTIFY_ADD_DEVICE:
+ if (dev->type == &i2c_adapter_type)
+ psmouse_smbus_check_adapter(to_i2c_adapter(dev));
+ break;
+
+ case BUS_NOTIFY_REMOVED_DEVICE:
+ if (dev->type == &i2c_client_type)
+ psmouse_smbus_detach_i2c_client(to_i2c_client(dev));
+ break;
+ }
+
+ return 0;
+}
+
+static struct notifier_block psmouse_smbus_notifier = {
+ .notifier_call = psmouse_smbus_notifier_call,
+};
+
+static psmouse_ret_t psmouse_smbus_process_byte(struct psmouse *psmouse)
+{
+ return PSMOUSE_FULL_PACKET;
+}
+
+static int psmouse_smbus_reconnect(struct psmouse *psmouse)
+{
+ psmouse_deactivate(psmouse);
+
+ return 0;
+}
+
+struct psmouse_smbus_removal_work {
+ struct work_struct work;
+ struct i2c_client *client;
+};
+
+static void psmouse_smbus_remove_i2c_device(struct work_struct *work)
+{
+ struct psmouse_smbus_removal_work *rwork =
+ container_of(work, struct psmouse_smbus_removal_work, work);
+
+ dev_dbg(&rwork->client->dev, "destroying SMBus companion device\n");
+ i2c_unregister_device(rwork->client);
+
+ kfree(rwork);
+}
+
+/*
+ * This schedules removal of SMBus companion device. We have to do
+ * it in a separate tread to avoid deadlocking on psmouse_mutex in
+ * case the device has a trackstick (which is also driven by psmouse).
+ *
+ * Note that this may be racing with i2c adapter removal, but we
+ * can't do anything about that: i2c automatically destroys clients
+ * attached to an adapter that is being removed. This has to be
+ * fixed in i2c core.
+ */
+static void psmouse_smbus_schedule_remove(struct i2c_client *client)
+{
+ struct psmouse_smbus_removal_work *rwork;
+
+ rwork = kzalloc(sizeof(*rwork), GFP_KERNEL);
+ if (rwork) {
+ INIT_WORK(&rwork->work, psmouse_smbus_remove_i2c_device);
+ rwork->client = client;
+
+ schedule_work(&rwork->work);
+ }
+}
+
+static void psmouse_smbus_disconnect(struct psmouse *psmouse)
+{
+ struct psmouse_smbus_dev *smbdev = psmouse->private;
+
+ mutex_lock(&psmouse_smbus_mutex);
+ list_del(&smbdev->node);
+ mutex_unlock(&psmouse_smbus_mutex);
+
+ if (smbdev->client) {
+ psmouse_dbg(smbdev->psmouse,
+ "posting removal request for SMBus companion %s\n",
+ dev_name(&smbdev->client->dev));
+ psmouse_smbus_schedule_remove(smbdev->client);
+ }
+
+ kfree(smbdev);
+ psmouse->private = NULL;
+}
+
+struct psmouse_smbus_companion_req {
+ struct i2c_board_info *board;
+ struct i2c_client **client;
+};
+
+static int psmouse_smbus_create_companion(struct device *dev, void *data)
+{
+ struct psmouse_smbus_companion_req *req = data;
+ unsigned short addr[] = { req->board->addr, I2C_CLIENT_END };
+ struct i2c_adapter *adapter;
+
+ adapter = i2c_verify_adapter(dev);
+ if (!adapter)
+ return 0;
+
+ if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_HOST_NOTIFY))
+ return 0;
+
+ *req->client = i2c_new_probed_device(adapter, req->board, addr, NULL);
+ if (!*req->client)
+ return 0;
+
+ /* We have our(?) device, stop iterating i2c bus. */
+ return 1;
+}
+
+void psmouse_smbus_cleanup(struct psmouse *psmouse)
+{
+ struct psmouse_smbus_dev *smbdev, *tmp;
+
+ mutex_lock(&psmouse_smbus_mutex);
+
+ list_for_each_entry_safe(smbdev, tmp, &psmouse_smbus_list, node) {
+ if (psmouse == smbdev->psmouse) {
+ list_del(&smbdev->node);
+ kfree(smbdev);
+ }
+ }
+
+ mutex_unlock(&psmouse_smbus_mutex);
+}
+
+int psmouse_smbus_init(struct psmouse *psmouse, struct i2c_board_info *board,
+ bool leave_breadcrumbs)
+{
+ struct psmouse_smbus_companion_req req;
+ struct psmouse_smbus_dev *smbdev;
+ int error;
+
+ smbdev = kzalloc(sizeof(*smbdev), GFP_KERNEL);
+ if (!smbdev)
+ return -ENOMEM;
+
+ smbdev->psmouse = psmouse;
+ smbdev->addr = board->addr;
+
+ psmouse->private = smbdev;
+ psmouse->protocol_handler = psmouse_smbus_process_byte;
+ psmouse->reconnect = psmouse_smbus_reconnect;
+ psmouse->fast_reconnect = psmouse_smbus_reconnect;
+ psmouse->disconnect = psmouse_smbus_disconnect;
+ psmouse->resync_time = 0;
+
+ psmouse_deactivate(psmouse);
+
+ mutex_lock(&psmouse_smbus_mutex);
+ list_add_tail(&smbdev->node, &psmouse_smbus_list);
+ mutex_unlock(&psmouse_smbus_mutex);
+
+ /* Bind to already existing adapters right away */
+ req.board = board;
+ req.client = &smbdev->client;
+ error = i2c_for_each_dev(&req, psmouse_smbus_create_companion);
+
+ if (smbdev->client) {
+ /* We have our companion device */
+ return 0;
+ }
+
+ if (error < 0 || !leave_breadcrumbs) {
+ mutex_lock(&psmouse_smbus_mutex);
+ list_del(&smbdev->node);
+ mutex_unlock(&psmouse_smbus_mutex);
+
+ kfree(smbdev);
+ }
+
+ return error < 0 ? error : -EAGAIN;
+}
+
+int __init psmouse_smbus_module_init(void)
+{
+ int error;
+
+ error = bus_register_notifier(&i2c_bus_type, &psmouse_smbus_notifier);
+ if (error) {
+ pr_err("failed to register i2c bus notifier: %d\n", error);
+ return error;
+ }
+
+ return 0;
+}
+
+void __exit psmouse_smbus_module_exit(void)
+{
+ bus_unregister_notifier(&i2c_bus_type, &psmouse_smbus_notifier);
+ flush_scheduled_work();
+}
diff --git a/drivers/input/mouse/psmouse.h b/drivers/input/mouse/psmouse.h
index e853dee05e79..186c760e398e 100644
--- a/drivers/input/mouse/psmouse.h
+++ b/drivers/input/mouse/psmouse.h
@@ -209,5 +209,38 @@ static struct psmouse_attribute psmouse_attr_##_name = { \
&(psmouse)->ps2dev.serio->dev, \
psmouse_fmt(format), ##__VA_ARGS__)

+#ifdef CONFIG_MOUSE_PS2_SMBUS
+
+int psmouse_smbus_module_init(void);
+void psmouse_smbus_module_exit(void);
+
+struct i2c_board_info;
+
+int psmouse_smbus_init(struct psmouse *psmouse, struct i2c_board_info *board,
+ bool leave_breadcrumbs);
+void psmouse_smbus_cleanup(struct psmouse *psmouse);
+
+#else /* !CONFIG_MOUSE_PS2_SMBUS */
+
+static inline int psmouse_smbus_module_init(void)
+{
+ return 0;
+}
+
+static inline void psmouse_smbus_module_exit(void)
+{
+}
+
+int psmouse_smbus_init(struct psmouse *psmouse, struct i2c_board_info *board,
+ bool leave_breadcrumbs)
+{
+ return -ENOSYS;
+}
+
+void psmouse_smbus_cleanup(struct psmouse *psmouse)
+{
+}
+
+#endif /* CONFIG_MOUSE_PS2_SMBUS */

#endif /* _PSMOUSE_H */
--
2.12.0.246.ga2ecc84866-goog