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SubjectRe: [PATCH v2 6/9] Input: psmouse - add support for SMBus companions
On Mar 10 2017 or thereabouts, Dmitry Torokhov wrote:
> 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 | 291 ++++++++++++++++++++++++++++++++++++
> drivers/input/mouse/psmouse.h | 37 +++++
> 5 files changed, 348 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..cc716977fbf9
> --- /dev/null
> +++ b/drivers/input/mouse/psmouse-smbus.c
> @@ -0,0 +1,291 @@
> +/*
> + * 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 i2c_board_info board;
> + struct psmouse *psmouse;
> + struct i2c_client *client;
> + struct list_head node;
> + 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->board.addr) < 0)
> + continue;

These 2 lines above seem to be the culprit of the
non-working-on-the-t450s-while-in-bzImage :)

First, i2c_probe_func_quick_read() returns a boolean, so the value can
never be negative. And second, if you try to probe the device on the I2C
bus while psmouse_activate has been called, the device won't answer. So
we can simply ignore the call all together and let i2c_new_probed_device()
checks for the validity of the device.

Bonus point, if I remove the call to i2c_probe_func_quick_read(), I seem
to have reliable detection of SMBus even when psmouse in compiled in the
bzImage.


> +
> + /* 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);
> + }
> + }
> +
> + kfree(client->dev.platform_data);
> + client->dev.platform_data = NULL;
> +
> + 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;
> +}
> +
> +static int psmouse_smbus_create_companion(struct device *dev, void *data)
> +{
> + struct psmouse_smbus_dev *smbdev = data;
> + unsigned short addr_list[] = { smbdev->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;
> +
> + smbdev->client = i2c_new_probed_device(adapter, &smbdev->board,
> + addr_list, NULL);
> + if (!smbdev->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,
> + const struct i2c_board_info *board,
> + const void *pdata, size_t pdata_size,
> + bool leave_breadcrumbs)
> +{
> + struct psmouse_smbus_dev *smbdev;
> + int error;
> +
> + smbdev = kzalloc(sizeof(*smbdev), GFP_KERNEL);
> + if (!smbdev)
> + return -ENOMEM;
> +
> + smbdev->psmouse = psmouse;
> + smbdev->board = *board;
> +
> + smbdev->board.platform_data = kmemdup(pdata, pdata_size, GFP_KERNEL);
> + if (!smbdev->board.platform_data) {
> + kfree(smbdev);
> + return -ENOMEM;
> + }
> +
> + 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 */
> + error = i2c_for_each_dev(smbdev, psmouse_smbus_create_companion);
> +
> + if (smbdev->client) {
> + /* We have our companion device */
> + return 0;
> + }
> +
> + /*
> + * If we did not create i2c device we will not need platform
> + * data even if we are leaving breadcrumbs.
> + */
> + kfree(smbdev->board.platform_data);
> + smbdev->board.platform_data = NULL;
> +
> + 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)

This raises a new section mismatch warning:

WARNING: drivers/input/mouse/psmouse.o(.init.text+0x7c): Section mismatch in reference from the function psmouse_init() to the function .exit.text:psmouse_s
The function __init psmouse_init() references
a function __exit psmouse_smbus_module_exit().
This is often seen when error handling in the init function
uses functionality in the exit path.
The fix is often to remove the __exit annotation of
psmouse_smbus_module_exit() so it may be used outside an exit section.

As mentioned, dropping the __exit tag solves the issue.

With these 2 changes, the series is:
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

Thanks again for the respin!

Cheers,
Benjamin


> +{
> + 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..77fcd361c8d6 100644
> --- a/drivers/input/mouse/psmouse.h
> +++ b/drivers/input/mouse/psmouse.h
> @@ -209,5 +209,42 @@ 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,
> + const struct i2c_board_info *board,
> + const void *pdata, size_t pdata_size,
> + 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,
> + const struct i2c_board_info *board,
> + const void *pdata, size_t pdata_size,
> + 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
>

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