Re: [PATCH 08/10] Input: add a PS/2 to SMBus platform module

[Benjamin Tissoires]

On Tue, Jan 10, 2017 at 5:11 PM, Benjamin Tissoires
<benjamin.tissoires@xxxxxxxxxx> wrote:
> This driver is a glue between PS/2 devices that enumerate
> the RMI4 devices and Elan touchpads to the RMI4 (or Elan)
> SMBus driver.
>
> We use an intermediate platform device to not add a
> dependency between psmouse and I2C. It also handles
> the subtleties of going around the serio mutex lock by
> deferring the i2c creation/destruction in a separate
> thread.
>
> Signed-off-by: Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>
> ---
>  drivers/input/misc/Kconfig     |  11 ++
>  drivers/input/misc/Makefile    |   1 +
>  drivers/input/misc/ps2_smbus.c | 255 +++++++++++++++++++++++++++++++++++++++++
>  drivers/input/rmi4/Kconfig     |   1 +
>  4 files changed, 268 insertions(+)
>  create mode 100644 drivers/input/misc/ps2_smbus.c
>
> diff --git a/drivers/input/misc/Kconfig b/drivers/input/misc/Kconfig
> index 1ae4d96..e0dfefc 100644
> --- a/drivers/input/misc/Kconfig
> +++ b/drivers/input/misc/Kconfig
> @@ -832,4 +832,15 @@ config INPUT_HISI_POWERKEY
>           To compile this driver as a module, choose M here: the
>           module will be called hisi_powerkey.
>
> +config PS2_SMBUS
> +       tristate "Platform Support for PS/2 Nodes also connected over SMBus"
> +       depends on I2C
> +       help
> +         Say Y here if you want to support RMI4 or Elan devices connected to
> +         an SMB bus but enumerated through PS/2.
> +
> +         if unsure, say N.
> +         To compile this driver as a module, choose M here: the module will be
> +         called ps2_smbus.
> +
>  endif
> diff --git a/drivers/input/misc/Makefile b/drivers/input/misc/Makefile
> index 0b6d025..094a911 100644
> --- a/drivers/input/misc/Makefile
> +++ b/drivers/input/misc/Makefile
> @@ -57,6 +57,7 @@ obj-$(CONFIG_INPUT_PCSPKR)            += pcspkr.o
>  obj-$(CONFIG_INPUT_PM8941_PWRKEY)      += pm8941-pwrkey.o
>  obj-$(CONFIG_INPUT_PM8XXX_VIBRATOR)    += pm8xxx-vibrator.o
>  obj-$(CONFIG_INPUT_PMIC8XXX_PWRKEY)    += pmic8xxx-pwrkey.o
> +obj-$(CONFIG_PS2_SMBUS)                        += ps2_smbus.o
>  obj-$(CONFIG_INPUT_POWERMATE)          += powermate.o
>  obj-$(CONFIG_INPUT_PWM_BEEPER)         += pwm-beeper.o
>  obj-$(CONFIG_INPUT_RB532_BUTTON)       += rb532_button.o
> diff --git a/drivers/input/misc/ps2_smbus.c b/drivers/input/misc/ps2_smbus.c
> new file mode 100644
> index 0000000..d1f27ed
> --- /dev/null
> +++ b/drivers/input/misc/ps2_smbus.c
> @@ -0,0 +1,255 @@
> +/*
> + * 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.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/platform_device.h>
> +#include <linux/rmi.h>
> +#include <linux/serio.h>
> +#include <linux/slab.h>
> +
> +MODULE_AUTHOR("Benjamin Tissoires <benjamin.tissoires@xxxxxxxxxx>");
> +MODULE_DESCRIPTION("Platform PS/2 - SMBus bridge driver");
> +MODULE_LICENSE("GPL");
> +
> +static struct workqueue_struct *kps2smbus_wq;
> +DEFINE_MUTEX(ps2smbus_mutex);
> +
> +enum ps2smbus_type {
> +       PS2SMBUS_SYNAPTICS_RMI4,
> +};
> +
> +struct ps2smbus {
> +       struct i2c_client *smbus_client;
> +       struct notifier_block i2c_notifier;
> +       enum ps2smbus_type type;
> +       void *pdata;
> +};
> +
> +enum ps2smbus_event_type {
> +       PS2SMBUS_REGISTER_DEVICE,
> +       PS2SMBUS_UNREGISTER_DEVICE,
> +};
> +
> +struct ps2smbus_work {
> +       struct work_struct work;
> +       enum ps2smbus_event_type type;
> +       struct ps2smbus *ps2smbus;
> +       struct i2c_adapter *adap;
> +};
> +
> +static void ps2smbus_create_rmi4(struct ps2smbus *ps2smbus,
> +                                struct i2c_adapter *adap)
> +{
> +       const struct i2c_board_info i2c_info = {
> +               I2C_BOARD_INFO("rmi4_smbus", 0x2c),
> +               .platform_data = ps2smbus->pdata,
> +               .flags = I2C_CLIENT_HOST_NOTIFY,
> +       };
> +
> +       ps2smbus->smbus_client = i2c_new_device(adap, &i2c_info);
> +}
> +
> +static void ps2smbus_worker(struct work_struct *work)
> +{
> +       struct ps2smbus_work *ps2smbus_work;
> +       struct i2c_client *client;
> +
> +       ps2smbus_work = container_of(work, struct ps2smbus_work, work);
> +       client = ps2smbus_work->ps2smbus->smbus_client;
> +
> +       mutex_lock(&ps2smbus_mutex);
> +
> +       switch (ps2smbus_work->type) {
> +       case PS2SMBUS_REGISTER_DEVICE:
> +               if (ps2smbus_work->ps2smbus->type == PS2SMBUS_SYNAPTICS_RMI4)
> +                       ps2smbus_create_rmi4(ps2smbus_work->ps2smbus,
> +                                            ps2smbus_work->adap);
> +               break;
> +       case PS2SMBUS_UNREGISTER_DEVICE:
> +               if (client)
> +                       i2c_unregister_device(client);
> +               break;
> +       }
> +
> +       kfree(ps2smbus_work);
> +
> +       mutex_unlock(&ps2smbus_mutex);
> +}
> +
> +static int ps2smbus_schedule_work(enum ps2smbus_event_type type,
> +                                 struct ps2smbus *ps2smbus,
> +                                 struct i2c_adapter *adap)
> +{
> +       struct ps2smbus_work *ps2smbus_work;
> +
> +       ps2smbus_work = kzalloc(sizeof(*ps2smbus_work), GFP_KERNEL);
> +       if (!ps2smbus_work)
> +               return -ENOMEM;
> +
> +       ps2smbus_work->type = type;
> +       ps2smbus_work->ps2smbus = ps2smbus;
> +       ps2smbus_work->adap = adap;
> +
> +       INIT_WORK(&ps2smbus_work->work, ps2smbus_worker);
> +
> +       queue_work(kps2smbus_wq, &ps2smbus_work->work);
> +
> +       return 0;
> +}
> +
> +static int ps2smbus_attach_i2c_device(struct device *dev, void *data)
> +{
> +       struct ps2smbus *ps2smbus = data;
> +       struct i2c_adapter *adap;
> +
> +       if (dev->type != &i2c_adapter_type)
> +               return 0;
> +
> +       adap = to_i2c_adapter(dev);
> +
> +       if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_HOST_NOTIFY))
> +               return 0;
> +
> +       if (ps2smbus->smbus_client)
> +               return 0;
> +
> +       ps2smbus_schedule_work(PS2SMBUS_REGISTER_DEVICE, ps2smbus, adap);
> +
> +       pr_debug("ps2smbus: adapter [%s] registered\n", adap->name);
> +       return 0;
> +}
> +
> +static int ps2smbus_detach_i2c_device(struct device *dev,
> +                                     struct ps2smbus *ps2smbus)
> +{
> +       struct i2c_client *client;
> +
> +       if (dev->type == &i2c_adapter_type)
> +               return 0;
> +
> +       mutex_lock(&ps2smbus_mutex);
> +
> +       client = to_i2c_client(dev);
> +       if (client == ps2smbus->smbus_client)
> +               ps2smbus->smbus_client = NULL;
> +
> +       mutex_unlock(&ps2smbus_mutex);
> +
> +       pr_debug("ps2smbus: client [%s] unregistered\n", client->name);
> +       return 0;
> +}
> +
> +static int ps2smbus_notifier_call(struct notifier_block *nb,
> +                                 unsigned long action, void *data)
> +{
> +       struct device *dev = data;
> +       struct ps2smbus *ps2smbus;
> +
> +       ps2smbus = container_of(nb, struct ps2smbus, i2c_notifier);
> +
> +       switch (action) {
> +       case BUS_NOTIFY_ADD_DEVICE:
> +               return ps2smbus_attach_i2c_device(dev, ps2smbus);
> +       case BUS_NOTIFY_DEL_DEVICE:
> +               return ps2smbus_detach_i2c_device(dev, ps2smbus);
> +       }
> +
> +       return 0;
> +}
> +
> +static int ps2smbus_probe(struct platform_device *pdev)
> +{
> +       struct rmi_device_platform_data *rmi_pdata = pdev->dev.platform_data;
> +       struct serio *parent;
> +       struct ps2smbus *ps2smbus;
> +       int error;
> +
> +       ps2smbus = devm_kzalloc(&pdev->dev, sizeof(struct ps2smbus),
> +                               GFP_KERNEL);
> +       if (!ps2smbus)
> +               return -ENOMEM;
> +
> +       ps2smbus->i2c_notifier.notifier_call = ps2smbus_notifier_call;
> +       ps2smbus->pdata = pdev->dev.platform_data;
> +       ps2smbus->type = pdev->id_entry->driver_data;
> +       if (pdev->dev.parent) {
> +               parent = to_serio_port(pdev->dev.parent);
> +               if (ps2smbus->type == PS2SMBUS_SYNAPTICS_RMI4)
> +                       rmi_pdata->parent = parent;
> +       }
> +
> +       /* Keep track of adapters which will be added or removed later */
> +       error = bus_register_notifier(&i2c_bus_type, &ps2smbus->i2c_notifier);
> +       if (error)
> +               return error;
> +
> +       /* Bind to already existing adapters right away */
> +       i2c_for_each_dev(ps2smbus, ps2smbus_attach_i2c_device);
> +
> +       platform_set_drvdata(pdev, ps2smbus);
> +
> +       return 0;
> +}
> +
> +static int ps2smbus_remove(struct platform_device *pdev)
> +{
> +       struct ps2smbus *ps2smbus = platform_get_drvdata(pdev);
> +
> +       bus_unregister_notifier(&i2c_bus_type, &ps2smbus->i2c_notifier);
> +
> +       if (ps2smbus->smbus_client)
> +               ps2smbus_schedule_work(PS2SMBUS_UNREGISTER_DEVICE, ps2smbus,
> +                                      NULL);
> +
> +       platform_set_drvdata(pdev, NULL);
> +
> +       return 0;
> +}
> +
> +static const struct platform_device_id ps2smbus_id_table[] = {
> +       { .name = "rmi4", .driver_data = PS2SMBUS_SYNAPTICS_RMI4 },
> +       { }
> +};
> +MODULE_DEVICE_TABLE(platform, ps2smbus_id_table);
> +
> +static struct platform_driver ps2smbus_drv = {
> +       .driver         = {
> +               .name   = "ps2smbus",
> +       },
> +       .probe          = ps2smbus_probe,
> +       .remove         = ps2smbus_remove,
> +       .id_table       = ps2smbus_id_table,
> +};
> +
> +static int __init ps2smbus_init(void)
> +{
> +       int err;
> +
> +       kps2smbus_wq = alloc_ordered_workqueue("kps2smbusd", WQ_MEM_RECLAIM);
> +       if (!kps2smbus_wq) {
> +               pr_err("failed to create kps2smbusd workqueue\n");
> +               return -ENOMEM;
> +       }
> +
> +       err = platform_driver_register(&ps2smbus_drv);
> +       if (err)
> +               destroy_workqueue(kps2smbus_wq);
> +
> +       return err;
> +}
> +
> +static void __exit ps2smbus_exit(void)
> +{
> +       platform_driver_unregister(&ps2smbus_drv);
> +       destroy_workqueue(kps2smbus_wq);
> +}
> +
> +module_init(ps2smbus_init);
> +module_exit(ps2smbus_exit);
> diff --git a/drivers/input/rmi4/Kconfig b/drivers/input/rmi4/Kconfig
> index 30cc627..eb74678 100644
> --- a/drivers/input/rmi4/Kconfig
> +++ b/drivers/input/rmi4/Kconfig
> @@ -30,6 +30,7 @@ config RMI4_SPI
>  config RMI4_SMB
>         tristate "RMI4 SMB Support"
>         depends on RMI4_CORE && I2C
> +       select RMI4_PLATFORM

I realized yesterday that it should be "select PS2_SMBUS" here :/

Other than that, any comments on the series?

Cheers,
Benjamin

>         help
>           Say Y here if you want to support RMI4 devices connected to an SMB
>           bus.
> --
> 2.9.3
>