blob: 9591a28bc38a9f40da8f9c53fb49c11a6396a968 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0+
/*
* Surface Serial Hub (SSH) driver for communication with the Surface/System
* Aggregator Module (SSAM/SAM).
*
* Provides access to a SAM-over-SSH connected EC via a controller device.
* Handles communication via requests as well as enabling, disabling, and
* relaying of events.
*
* Copyright (C) 2019-2022 Maximilian Luz <luzmaximilian@gmail.com>
*/
#include <linux/acpi.h>
#include <linux/atomic.h>
#include <linux/completion.h>
#include <linux/gpio/consumer.h>
#include <linux/kernel.h>
#include <linux/kref.h>
#include <linux/module.h>
#include <linux/pm.h>
#include <linux/serdev.h>
#include <linux/sysfs.h>
#include <linux/surface_aggregator/controller.h>
#include <linux/surface_aggregator/device.h>
#include "bus.h"
#include "controller.h"
#define CREATE_TRACE_POINTS
#include "trace.h"
/* -- Static controller reference. ------------------------------------------ */
/*
* Main controller reference. The corresponding lock must be held while
* accessing (reading/writing) the reference.
*/
static struct ssam_controller *__ssam_controller;
static DEFINE_SPINLOCK(__ssam_controller_lock);
/**
* ssam_get_controller() - Get reference to SSAM controller.
*
* Returns a reference to the SSAM controller of the system or %NULL if there
* is none, it hasn't been set up yet, or it has already been unregistered.
* This function automatically increments the reference count of the
* controller, thus the calling party must ensure that ssam_controller_put()
* is called when it doesn't need the controller any more.
*/
struct ssam_controller *ssam_get_controller(void)
{
struct ssam_controller *ctrl;
spin_lock(&__ssam_controller_lock);
ctrl = __ssam_controller;
if (!ctrl)
goto out;
if (WARN_ON(!kref_get_unless_zero(&ctrl->kref)))
ctrl = NULL;
out:
spin_unlock(&__ssam_controller_lock);
return ctrl;
}
EXPORT_SYMBOL_GPL(ssam_get_controller);
/**
* ssam_try_set_controller() - Try to set the main controller reference.
* @ctrl: The controller to which the reference should point.
*
* Set the main controller reference to the given pointer if the reference
* hasn't been set already.
*
* Return: Returns zero on success or %-EEXIST if the reference has already
* been set.
*/
static int ssam_try_set_controller(struct ssam_controller *ctrl)
{
int status = 0;
spin_lock(&__ssam_controller_lock);
if (!__ssam_controller)
__ssam_controller = ctrl;
else
status = -EEXIST;
spin_unlock(&__ssam_controller_lock);
return status;
}
/**
* ssam_clear_controller() - Remove/clear the main controller reference.
*
* Clears the main controller reference, i.e. sets it to %NULL. This function
* should be called before the controller is shut down.
*/
static void ssam_clear_controller(void)
{
spin_lock(&__ssam_controller_lock);
__ssam_controller = NULL;
spin_unlock(&__ssam_controller_lock);
}
/**
* ssam_client_link() - Link an arbitrary client device to the controller.
* @c: The controller to link to.
* @client: The client device.
*
* Link an arbitrary client device to the controller by creating a device link
* between it as consumer and the controller device as provider. This function
* can be used for non-SSAM devices (or SSAM devices not registered as child
* under the controller) to guarantee that the controller is valid for as long
* as the driver of the client device is bound, and that proper suspend and
* resume ordering is guaranteed.
*
* The device link does not have to be destructed manually. It is removed
* automatically once the driver of the client device unbinds.
*
* Return: Returns zero on success, %-ENODEV if the controller is not ready or
* going to be removed soon, or %-ENOMEM if the device link could not be
* created for other reasons.
*/
int ssam_client_link(struct ssam_controller *c, struct device *client)
{
const u32 flags = DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_CONSUMER;
struct device_link *link;
struct device *ctrldev;
ssam_controller_statelock(c);
if (c->state != SSAM_CONTROLLER_STARTED) {
ssam_controller_stateunlock(c);
return -ENODEV;
}
ctrldev = ssam_controller_device(c);
if (!ctrldev) {
ssam_controller_stateunlock(c);
return -ENODEV;
}
link = device_link_add(client, ctrldev, flags);
if (!link) {
ssam_controller_stateunlock(c);
return -ENOMEM;
}
/*
* Return -ENODEV if supplier driver is on its way to be removed. In
* this case, the controller won't be around for much longer and the
* device link is not going to save us any more, as unbinding is
* already in progress.
*/
if (READ_ONCE(link->status) == DL_STATE_SUPPLIER_UNBIND) {
ssam_controller_stateunlock(c);
return -ENODEV;
}
ssam_controller_stateunlock(c);
return 0;
}
EXPORT_SYMBOL_GPL(ssam_client_link);
/**
* ssam_client_bind() - Bind an arbitrary client device to the controller.
* @client: The client device.
*
* Link an arbitrary client device to the controller by creating a device link
* between it as consumer and the main controller device as provider. This
* function can be used for non-SSAM devices to guarantee that the controller
* returned by this function is valid for as long as the driver of the client
* device is bound, and that proper suspend and resume ordering is guaranteed.
*
* This function does essentially the same as ssam_client_link(), except that
* it first fetches the main controller reference, then creates the link, and
* finally returns this reference. Note that this function does not increment
* the reference counter of the controller, as, due to the link, the
* controller lifetime is assured as long as the driver of the client device
* is bound.
*
* It is not valid to use the controller reference obtained by this method
* outside of the driver bound to the client device at the time of calling
* this function, without first incrementing the reference count of the
* controller via ssam_controller_get(). Even after doing this, care must be
* taken that requests are only submitted and notifiers are only
* (un-)registered when the controller is active and not suspended. In other
* words: The device link only lives as long as the client driver is bound and
* any guarantees enforced by this link (e.g. active controller state) can
* only be relied upon as long as this link exists and may need to be enforced
* in other ways afterwards.
*
* The created device link does not have to be destructed manually. It is
* removed automatically once the driver of the client device unbinds.
*
* Return: Returns the controller on success, an error pointer with %-ENODEV
* if the controller is not present, not ready or going to be removed soon, or
* %-ENOMEM if the device link could not be created for other reasons.
*/
struct ssam_controller *ssam_client_bind(struct device *client)
{
struct ssam_controller *c;
int status;
c = ssam_get_controller();
if (!c)
return ERR_PTR(-ENODEV);
status = ssam_client_link(c, client);
/*
* Note that we can drop our controller reference in both success and
* failure cases: On success, we have bound the controller lifetime
* inherently to the client driver lifetime, i.e. it the controller is
* now guaranteed to outlive the client driver. On failure, we're not
* going to use the controller any more.
*/
ssam_controller_put(c);
return status >= 0 ? c : ERR_PTR(status);
}
EXPORT_SYMBOL_GPL(ssam_client_bind);
/* -- Glue layer (serdev_device -> ssam_controller). ------------------------ */
static ssize_t ssam_receive_buf(struct serdev_device *dev, const u8 *buf,
size_t n)
{
struct ssam_controller *ctrl;
int ret;
ctrl = serdev_device_get_drvdata(dev);
ret = ssam_controller_receive_buf(ctrl, buf, n);
return ret < 0 ? 0 : ret;
}
static void ssam_write_wakeup(struct serdev_device *dev)
{
ssam_controller_write_wakeup(serdev_device_get_drvdata(dev));
}
static const struct serdev_device_ops ssam_serdev_ops = {
.receive_buf = ssam_receive_buf,
.write_wakeup = ssam_write_wakeup,
};
/* -- SysFS and misc. ------------------------------------------------------- */
static int ssam_log_firmware_version(struct ssam_controller *ctrl)
{
u32 version, a, b, c;
int status;
status = ssam_get_firmware_version(ctrl, &version);
if (status)
return status;
a = (version >> 24) & 0xff;
b = ((version >> 8) & 0xffff);
c = version & 0xff;
ssam_info(ctrl, "SAM firmware version: %u.%u.%u\n", a, b, c);
return 0;
}
static ssize_t firmware_version_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct ssam_controller *ctrl = dev_get_drvdata(dev);
u32 version, a, b, c;
int status;
status = ssam_get_firmware_version(ctrl, &version);
if (status < 0)
return status;
a = (version >> 24) & 0xff;
b = ((version >> 8) & 0xffff);
c = version & 0xff;
return sysfs_emit(buf, "%u.%u.%u\n", a, b, c);
}
static DEVICE_ATTR_RO(firmware_version);
static struct attribute *ssam_sam_attrs[] = {
&dev_attr_firmware_version.attr,
NULL
};
static const struct attribute_group ssam_sam_group = {
.name = "sam",
.attrs = ssam_sam_attrs,
};
/* -- ACPI based device setup. ---------------------------------------------- */
static acpi_status ssam_serdev_setup_via_acpi_crs(struct acpi_resource *rsc,
void *ctx)
{
struct serdev_device *serdev = ctx;
struct acpi_resource_uart_serialbus *uart;
bool flow_control;
int status = 0;
if (!serdev_acpi_get_uart_resource(rsc, &uart))
return AE_OK;
/* Set up serdev device. */
serdev_device_set_baudrate(serdev, uart->default_baud_rate);
/* serdev currently only supports RTSCTS flow control. */
if (uart->flow_control & (~((u8)ACPI_UART_FLOW_CONTROL_HW))) {
dev_warn(&serdev->dev, "setup: unsupported flow control (value: %#04x)\n",
uart->flow_control);
}
/* Set RTSCTS flow control. */
flow_control = uart->flow_control & ACPI_UART_FLOW_CONTROL_HW;
serdev_device_set_flow_control(serdev, flow_control);
/* serdev currently only supports EVEN/ODD parity. */
switch (uart->parity) {
case ACPI_UART_PARITY_NONE:
status = serdev_device_set_parity(serdev, SERDEV_PARITY_NONE);
break;
case ACPI_UART_PARITY_EVEN:
status = serdev_device_set_parity(serdev, SERDEV_PARITY_EVEN);
break;
case ACPI_UART_PARITY_ODD:
status = serdev_device_set_parity(serdev, SERDEV_PARITY_ODD);
break;
default:
dev_warn(&serdev->dev, "setup: unsupported parity (value: %#04x)\n",
uart->parity);
break;
}
if (status) {
dev_err(&serdev->dev, "setup: failed to set parity (value: %#04x, error: %d)\n",
uart->parity, status);
return AE_ERROR;
}
/* We've found the resource and are done. */
return AE_CTRL_TERMINATE;
}
static acpi_status ssam_serdev_setup_via_acpi(acpi_handle handle,
struct serdev_device *serdev)
{
return acpi_walk_resources(handle, METHOD_NAME__CRS,
ssam_serdev_setup_via_acpi_crs, serdev);
}
/* -- Power management. ----------------------------------------------------- */
static void ssam_serial_hub_shutdown(struct device *dev)
{
struct ssam_controller *c = dev_get_drvdata(dev);
int status;
/*
* Try to disable notifiers, signal display-off and D0-exit, ignore any
* errors.
*
* Note: It has not been established yet if this is actually
* necessary/useful for shutdown.
*/
status = ssam_notifier_disable_registered(c);
if (status) {
ssam_err(c, "pm: failed to disable notifiers for shutdown: %d\n",
status);
}
status = ssam_ctrl_notif_display_off(c);
if (status)
ssam_err(c, "pm: display-off notification failed: %d\n", status);
status = ssam_ctrl_notif_d0_exit(c);
if (status)
ssam_err(c, "pm: D0-exit notification failed: %d\n", status);
}
#ifdef CONFIG_PM_SLEEP
static int ssam_serial_hub_pm_prepare(struct device *dev)
{
struct ssam_controller *c = dev_get_drvdata(dev);
int status;
/*
* Try to signal display-off, This will quiesce events.
*
* Note: Signaling display-off/display-on should normally be done from
* some sort of display state notifier. As that is not available,
* signal it here.
*/
status = ssam_ctrl_notif_display_off(c);
if (status)
ssam_err(c, "pm: display-off notification failed: %d\n", status);
return status;
}
static void ssam_serial_hub_pm_complete(struct device *dev)
{
struct ssam_controller *c = dev_get_drvdata(dev);
int status;
/*
* Try to signal display-on. This will restore events.
*
* Note: Signaling display-off/display-on should normally be done from
* some sort of display state notifier. As that is not available,
* signal it here.
*/
status = ssam_ctrl_notif_display_on(c);
if (status)
ssam_err(c, "pm: display-on notification failed: %d\n", status);
}
static int ssam_serial_hub_pm_suspend(struct device *dev)
{
struct ssam_controller *c = dev_get_drvdata(dev);
int status;
/*
* Try to signal D0-exit, enable IRQ wakeup if specified. Abort on
* error.
*/
status = ssam_ctrl_notif_d0_exit(c);
if (status) {
ssam_err(c, "pm: D0-exit notification failed: %d\n", status);
goto err_notif;
}
status = ssam_irq_arm_for_wakeup(c);
if (status)
goto err_irq;
WARN_ON(ssam_controller_suspend(c));
return 0;
err_irq:
ssam_ctrl_notif_d0_entry(c);
err_notif:
ssam_ctrl_notif_display_on(c);
return status;
}
static int ssam_serial_hub_pm_resume(struct device *dev)
{
struct ssam_controller *c = dev_get_drvdata(dev);
int status;
WARN_ON(ssam_controller_resume(c));
/*
* Try to disable IRQ wakeup (if specified) and signal D0-entry. In
* case of errors, log them and try to restore normal operation state
* as far as possible.
*
* Note: Signaling display-off/display-on should normally be done from
* some sort of display state notifier. As that is not available,
* signal it here.
*/
ssam_irq_disarm_wakeup(c);
status = ssam_ctrl_notif_d0_entry(c);
if (status)
ssam_err(c, "pm: D0-entry notification failed: %d\n", status);
return 0;
}
static int ssam_serial_hub_pm_freeze(struct device *dev)
{
struct ssam_controller *c = dev_get_drvdata(dev);
int status;
/*
* During hibernation image creation, we only have to ensure that the
* EC doesn't send us any events. This is done via the display-off
* and D0-exit notifications. Note that this sets up the wakeup IRQ
* on the EC side, however, we have disabled it by default on our side
* and won't enable it here.
*
* See ssam_serial_hub_poweroff() for more details on the hibernation
* process.
*/
status = ssam_ctrl_notif_d0_exit(c);
if (status) {
ssam_err(c, "pm: D0-exit notification failed: %d\n", status);
ssam_ctrl_notif_display_on(c);
return status;
}
WARN_ON(ssam_controller_suspend(c));
return 0;
}
static int ssam_serial_hub_pm_thaw(struct device *dev)
{
struct ssam_controller *c = dev_get_drvdata(dev);
int status;
WARN_ON(ssam_controller_resume(c));
status = ssam_ctrl_notif_d0_entry(c);
if (status)
ssam_err(c, "pm: D0-exit notification failed: %d\n", status);
return status;
}
static int ssam_serial_hub_pm_poweroff(struct device *dev)
{
struct ssam_controller *c = dev_get_drvdata(dev);
int status;
/*
* When entering hibernation and powering off the system, the EC, at
* least on some models, may disable events. Without us taking care of
* that, this leads to events not being enabled/restored when the
* system resumes from hibernation, resulting SAM-HID subsystem devices
* (i.e. keyboard, touchpad) not working, AC-plug/AC-unplug events being
* gone, etc.
*
* To avoid these issues, we disable all registered events here (this is
* likely not actually required) and restore them during the drivers PM
* restore callback.
*
* Wakeup from the EC interrupt is not supported during hibernation,
* so don't arm the IRQ here.
*/
status = ssam_notifier_disable_registered(c);
if (status) {
ssam_err(c, "pm: failed to disable notifiers for hibernation: %d\n",
status);
return status;
}
status = ssam_ctrl_notif_d0_exit(c);
if (status) {
ssam_err(c, "pm: D0-exit notification failed: %d\n", status);
ssam_notifier_restore_registered(c);
return status;
}
WARN_ON(ssam_controller_suspend(c));
return 0;
}
static int ssam_serial_hub_pm_restore(struct device *dev)
{
struct ssam_controller *c = dev_get_drvdata(dev);
int status;
/*
* Ignore but log errors, try to restore state as much as possible in
* case of failures. See ssam_serial_hub_poweroff() for more details on
* the hibernation process.
*/
WARN_ON(ssam_controller_resume(c));
status = ssam_ctrl_notif_d0_entry(c);
if (status)
ssam_err(c, "pm: D0-entry notification failed: %d\n", status);
ssam_notifier_restore_registered(c);
return 0;
}
static const struct dev_pm_ops ssam_serial_hub_pm_ops = {
.prepare = ssam_serial_hub_pm_prepare,
.complete = ssam_serial_hub_pm_complete,
.suspend = ssam_serial_hub_pm_suspend,
.resume = ssam_serial_hub_pm_resume,
.freeze = ssam_serial_hub_pm_freeze,
.thaw = ssam_serial_hub_pm_thaw,
.poweroff = ssam_serial_hub_pm_poweroff,
.restore = ssam_serial_hub_pm_restore,
};
#else /* CONFIG_PM_SLEEP */
static const struct dev_pm_ops ssam_serial_hub_pm_ops = { };
#endif /* CONFIG_PM_SLEEP */
/* -- Device/driver setup. -------------------------------------------------- */
static const struct acpi_gpio_params gpio_ssam_wakeup_int = { 0, 0, false };
static const struct acpi_gpio_params gpio_ssam_wakeup = { 1, 0, false };
static const struct acpi_gpio_mapping ssam_acpi_gpios[] = {
{ "ssam_wakeup-int-gpio", &gpio_ssam_wakeup_int, 1 },
{ "ssam_wakeup-gpio", &gpio_ssam_wakeup, 1 },
{ },
};
static int ssam_serial_hub_probe(struct serdev_device *serdev)
{
struct acpi_device *ssh = ACPI_COMPANION(&serdev->dev);
struct ssam_controller *ctrl;
acpi_status astatus;
int status;
if (gpiod_count(&serdev->dev, NULL) < 0)
return -ENODEV;
status = devm_acpi_dev_add_driver_gpios(&serdev->dev, ssam_acpi_gpios);
if (status)
return status;
/* Allocate controller. */
ctrl = kzalloc(sizeof(*ctrl), GFP_KERNEL);
if (!ctrl)
return -ENOMEM;
/* Initialize controller. */
status = ssam_controller_init(ctrl, serdev);
if (status)
goto err_ctrl_init;
ssam_controller_lock(ctrl);
/* Set up serdev device. */
serdev_device_set_drvdata(serdev, ctrl);
serdev_device_set_client_ops(serdev, &ssam_serdev_ops);
status = serdev_device_open(serdev);
if (status)
goto err_devopen;
astatus = ssam_serdev_setup_via_acpi(ssh->handle, serdev);
if (ACPI_FAILURE(astatus)) {
status = -ENXIO;
goto err_devinit;
}
/* Start controller. */
status = ssam_controller_start(ctrl);
if (status)
goto err_devinit;
ssam_controller_unlock(ctrl);
/*
* Initial SAM requests: Log version and notify default/init power
* states.
*/
status = ssam_log_firmware_version(ctrl);
if (status)
goto err_initrq;
status = ssam_ctrl_notif_d0_entry(ctrl);
if (status)
goto err_initrq;
status = ssam_ctrl_notif_display_on(ctrl);
if (status)
goto err_initrq;
status = sysfs_create_group(&serdev->dev.kobj, &ssam_sam_group);
if (status)
goto err_initrq;
/* Set up IRQ. */
status = ssam_irq_setup(ctrl);
if (status)
goto err_irq;
/* Finally, set main controller reference. */
status = ssam_try_set_controller(ctrl);
if (WARN_ON(status)) /* Currently, we're the only provider. */
goto err_mainref;
/*
* TODO: The EC can wake up the system via the associated GPIO interrupt
* in multiple situations. One of which is the remaining battery
* capacity falling below a certain threshold. Normally, we should
* use the device_init_wakeup function, however, the EC also seems
* to have other reasons for waking up the system and it seems
* that Windows has additional checks whether the system should be
* resumed. In short, this causes some spurious unwanted wake-ups.
* For now let's thus default power/wakeup to false.
*/
device_set_wakeup_capable(&serdev->dev, true);
acpi_dev_clear_dependencies(ssh);
return 0;
err_mainref:
ssam_irq_free(ctrl);
err_irq:
sysfs_remove_group(&serdev->dev.kobj, &ssam_sam_group);
err_initrq:
ssam_controller_lock(ctrl);
ssam_controller_shutdown(ctrl);
err_devinit:
serdev_device_close(serdev);
err_devopen:
ssam_controller_destroy(ctrl);
ssam_controller_unlock(ctrl);
err_ctrl_init:
kfree(ctrl);
return status;
}
static void ssam_serial_hub_remove(struct serdev_device *serdev)
{
struct ssam_controller *ctrl = serdev_device_get_drvdata(serdev);
int status;
/* Clear static reference so that no one else can get a new one. */
ssam_clear_controller();
/* Disable and free IRQ. */
ssam_irq_free(ctrl);
sysfs_remove_group(&serdev->dev.kobj, &ssam_sam_group);
ssam_controller_lock(ctrl);
/* Remove all client devices. */
ssam_remove_clients(&serdev->dev);
/* Act as if suspending to silence events. */
status = ssam_ctrl_notif_display_off(ctrl);
if (status) {
dev_err(&serdev->dev, "display-off notification failed: %d\n",
status);
}
status = ssam_ctrl_notif_d0_exit(ctrl);
if (status) {
dev_err(&serdev->dev, "D0-exit notification failed: %d\n",
status);
}
/* Shut down controller and remove serdev device reference from it. */
ssam_controller_shutdown(ctrl);
/* Shut down actual transport. */
serdev_device_wait_until_sent(serdev, 0);
serdev_device_close(serdev);
/* Drop our controller reference. */
ssam_controller_unlock(ctrl);
ssam_controller_put(ctrl);
device_set_wakeup_capable(&serdev->dev, false);
}
static const struct acpi_device_id ssam_serial_hub_match[] = {
{ "MSHW0084", 0 },
{ },
};
MODULE_DEVICE_TABLE(acpi, ssam_serial_hub_match);
static struct serdev_device_driver ssam_serial_hub = {
.probe = ssam_serial_hub_probe,
.remove = ssam_serial_hub_remove,
.driver = {
.name = "surface_serial_hub",
.acpi_match_table = ssam_serial_hub_match,
.pm = &ssam_serial_hub_pm_ops,
.shutdown = ssam_serial_hub_shutdown,
.probe_type = PROBE_PREFER_ASYNCHRONOUS,
},
};
/* -- Module setup. --------------------------------------------------------- */
static int __init ssam_core_init(void)
{
int status;
status = ssam_bus_register();
if (status)
goto err_bus;
status = ssh_ctrl_packet_cache_init();
if (status)
goto err_cpkg;
status = ssam_event_item_cache_init();
if (status)
goto err_evitem;
status = serdev_device_driver_register(&ssam_serial_hub);
if (status)
goto err_register;
return 0;
err_register:
ssam_event_item_cache_destroy();
err_evitem:
ssh_ctrl_packet_cache_destroy();
err_cpkg:
ssam_bus_unregister();
err_bus:
return status;
}
subsys_initcall(ssam_core_init);
static void __exit ssam_core_exit(void)
{
serdev_device_driver_unregister(&ssam_serial_hub);
ssam_event_item_cache_destroy();
ssh_ctrl_packet_cache_destroy();
ssam_bus_unregister();
}
module_exit(ssam_core_exit);
MODULE_AUTHOR("Maximilian Luz <luzmaximilian@gmail.com>");
MODULE_DESCRIPTION("Subsystem and Surface Serial Hub driver for Surface System Aggregator Module");
MODULE_LICENSE("GPL");