// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Support for the custom fast charging protocol found on the Lenovo Yoga
* Tablet 2 1380F / 1380L models.
*
* Copyright (C) 2024 Hans de Goede <[email protected]>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/extcon.h>
#include <linux/gpio/consumer.h>
#include <linux/module.h>
#include <linux/notifier.h>
#include <linux/pinctrl/consumer.h>
#include <linux/pinctrl/machine.h>
#include <linux/platform_device.h>
#include <linux/serdev.h>
#include <linux/time.h>
#include <linux/types.h>
#include <linux/workqueue.h>
#include "serdev_helpers.h"
#define YT2_1380_FC_PDEV_NAME "lenovo-yoga-tab2-pro-1380-fastcharger"
#define YT2_1380_FC_SERDEV_CTRL "serial0"
#define YT2_1380_FC_SERDEV_NAME "serial0-0"
#define YT2_1380_FC_EXTCON_NAME "i2c-lc824206xa"
#define YT2_1380_FC_MAX_TRIES 5
#define YT2_1380_FC_PIN_SW_DELAY_US (10 * USEC_PER_MSEC)
#define YT2_1380_FC_UART_DRAIN_DELAY_US (50 * USEC_PER_MSEC)
#define YT2_1380_FC_VOLT_SW_DELAY_US (1000 * USEC_PER_MSEC)
struct yt2_1380_fc {
struct device *dev;
struct pinctrl *pinctrl;
struct pinctrl_state *gpio_state;
struct pinctrl_state *uart_state;
struct gpio_desc *uart3_txd;
struct gpio_desc *uart3_rxd;
struct extcon_dev *extcon;
struct notifier_block nb;
struct work_struct work;
bool fast_charging;
};
static int yt2_1380_fc_set_gpio_mode(struct yt2_1380_fc *fc, bool enable)
{
struct pinctrl_state *state = enable ? fc->gpio_state : fc->uart_state;
int ret;
ret = pinctrl_select_state(fc->pinctrl, state);
if (ret) {
dev_err(fc->dev, "Error %d setting pinctrl state\n", ret);
return ret;
}
fsleep(YT2_1380_FC_PIN_SW_DELAY_US);
return 0;
}
static bool yt2_1380_fc_dedicated_charger_connected(struct yt2_1380_fc *fc)
{
return extcon_get_state(fc->extcon, EXTCON_CHG_USB_DCP) > 0;
}
static bool yt2_1380_fc_fast_charger_connected(struct yt2_1380_fc *fc)
{
return extcon_get_state(fc->extcon, EXTCON_CHG_USB_FAST) > 0;
}
static void yt2_1380_fc_worker(struct work_struct *work)
{
struct yt2_1380_fc *fc = container_of(work, struct yt2_1380_fc, work);
int i, ret;
/* Do nothing if already fast charging */
if (yt2_1380_fc_fast_charger_connected(fc))
return;
for (i = 0; i < YT2_1380_FC_MAX_TRIES; i++) {
/* Set pins to UART mode (for charger disconnect and retries) */
ret = yt2_1380_fc_set_gpio_mode(fc, false);
if (ret)
return;
/* Only try 12V charging if a dedicated charger is detected */
if (!yt2_1380_fc_dedicated_charger_connected(fc))
return;
/* Send the command to switch to 12V charging */
ret = serdev_device_write_buf(to_serdev_device(fc->dev), "SC", strlen("SC"));
if (ret != strlen("SC")) {
dev_err(fc->dev, "Error %d writing to uart\n", ret);
return;
}
fsleep(YT2_1380_FC_UART_DRAIN_DELAY_US);
/* Re-check a charger is still connected */
if (!yt2_1380_fc_dedicated_charger_connected(fc))
return;
/*
* Now switch the lines to GPIO (output, high). The charger
* expects the lines being driven high after the command.
* Presumably this is used to detect the tablet getting
* unplugged (to switch back to 5V output on unplug).
*/
ret = yt2_1380_fc_set_gpio_mode(fc, true);
if (ret)
return;
fsleep(YT2_1380_FC_VOLT_SW_DELAY_US);
if (yt2_1380_fc_fast_charger_connected(fc))
return; /* Success */
}
dev_dbg(fc->dev, "Failed to switch to 12V charging (not the original charger?)\n");
/* Failed to enable 12V fast charging, reset pins to default UART mode */
yt2_1380_fc_set_gpio_mode(fc, false);
}
static int yt2_1380_fc_extcon_evt(struct notifier_block *nb,
unsigned long event, void *param)
{
struct yt2_1380_fc *fc = container_of(nb, struct yt2_1380_fc, nb);
schedule_work(&fc->work);
return NOTIFY_OK;
}
static size_t yt2_1380_fc_receive(struct serdev_device *serdev, const u8 *data, size_t len)
{
/*
* Since the USB data lines are shorted for DCP detection, echos of
* the "SC" command send in yt2_1380_fc_worker() will be received.
*/
dev_dbg(&serdev->dev, "recv: %*ph\n", (int)len, data);
return len;
}
static const struct serdev_device_ops yt2_1380_fc_serdev_ops = {
.receive_buf = yt2_1380_fc_receive,
.write_wakeup = serdev_device_write_wakeup,
};
static int yt2_1380_fc_serdev_probe(struct serdev_device *serdev)
{
struct device *dev = &serdev->dev;
struct yt2_1380_fc *fc;
int ret;
fc = devm_kzalloc(dev, sizeof(*fc), GFP_KERNEL);
if (!fc)
return -ENOMEM;
fc->dev = dev;
fc->nb.notifier_call = yt2_1380_fc_extcon_evt;
INIT_WORK(&fc->work, yt2_1380_fc_worker);
/*
* Do this first since it may return -EPROBE_DEFER.
* There is no extcon_put(), so there is no need to free this.
*/
fc->extcon = extcon_get_extcon_dev(YT2_1380_FC_EXTCON_NAME);
if (IS_ERR(fc->extcon))
return dev_err_probe(dev, PTR_ERR(fc->extcon), "getting extcon\n");
fc->pinctrl = devm_pinctrl_get(dev);
if (IS_ERR(fc->pinctrl))
return dev_err_probe(dev, PTR_ERR(fc->pinctrl), "getting pinctrl\n");
/*
* To switch the UART3 pins connected to the USB data lines between
* UART and GPIO modes.
*/
fc->gpio_state = pinctrl_lookup_state(fc->pinctrl, "uart3_gpio");
fc->uart_state = pinctrl_lookup_state(fc->pinctrl, "uart3_uart");
if (IS_ERR(fc->gpio_state) || IS_ERR(fc->uart_state))
return dev_err_probe(dev, -EINVAL, "getting pinctrl states\n");
ret = yt2_1380_fc_set_gpio_mode(fc, true);
if (ret)
return ret;
fc->uart3_txd = devm_gpiod_get(dev, "uart3_txd", GPIOD_OUT_HIGH);
if (IS_ERR(fc->uart3_txd))
return dev_err_probe(dev, PTR_ERR(fc->uart3_txd), "getting uart3_txd gpio\n");
fc->uart3_rxd = devm_gpiod_get(dev, "uart3_rxd", GPIOD_OUT_HIGH);
if (IS_ERR(fc->uart3_rxd))
return dev_err_probe(dev, PTR_ERR(fc->uart3_rxd), "getting uart3_rxd gpio\n");
ret = yt2_1380_fc_set_gpio_mode(fc, false);
if (ret)
return ret;
ret = devm_serdev_device_open(dev, serdev);
if (ret)
return dev_err_probe(dev, ret, "opening UART device\n");
serdev_device_set_baudrate(serdev, 600);
serdev_device_set_flow_control(serdev, false);
serdev_device_set_drvdata(serdev, fc);
serdev_device_set_client_ops(serdev, &yt2_1380_fc_serdev_ops);
ret = devm_extcon_register_notifier_all(dev, fc->extcon, &fc->nb);
if (ret)
return dev_err_probe(dev, ret, "registering extcon notifier\n");
/* In case the extcon already has detected a DCP charger */
schedule_work(&fc->work);
return 0;
}
struct serdev_device_driver yt2_1380_fc_serdev_driver = {
.probe = yt2_1380_fc_serdev_probe,
.driver = {
.name = KBUILD_MODNAME,
},
};
static const struct pinctrl_map yt2_1380_fc_pinctrl_map[] = {
PIN_MAP_MUX_GROUP(YT2_1380_FC_SERDEV_NAME, "uart3_uart",
"INT33FC:00", "uart3_grp", "uart"),
PIN_MAP_MUX_GROUP(YT2_1380_FC_SERDEV_NAME, "uart3_gpio",
"INT33FC:00", "uart3_grp_gpio", "gpio"),
};
static int yt2_1380_fc_pdev_probe(struct platform_device *pdev)
{
struct serdev_device *serdev;
struct device *ctrl_dev;
int ret;
/* Register pinctrl mappings for setting the UART3 pins mode */
ret = pinctrl_register_mappings(yt2_1380_fc_pinctrl_map,
ARRAY_SIZE(yt2_1380_fc_pinctrl_map));
if (ret)
return ret;
/* And create the serdev to talk to the charger over the UART3 pins */
ctrl_dev = get_serdev_controller("PNP0501", "1", 0, YT2_1380_FC_SERDEV_CTRL);
if (IS_ERR(ctrl_dev)) {
ret = PTR_ERR(ctrl_dev);
goto out_pinctrl_unregister_mappings;
}
serdev = serdev_device_alloc(to_serdev_controller(ctrl_dev));
put_device(ctrl_dev);
if (!serdev) {
ret = -ENOMEM;
goto out_pinctrl_unregister_mappings;
}
ret = serdev_device_add(serdev);
if (ret) {
dev_err_probe(&pdev->dev, ret, "adding serdev\n");
serdev_device_put(serdev);
goto out_pinctrl_unregister_mappings;
}
/*
* serdev device <-> driver matching relies on OF or ACPI matches and
* neither is available here, manually bind the driver.
*/
ret = device_driver_attach(&yt2_1380_fc_serdev_driver.driver, &serdev->dev);
if (ret) {
/* device_driver_attach() maps EPROBE_DEFER to EAGAIN, map it back */
ret = (ret == -EAGAIN) ? -EPROBE_DEFER : ret;
dev_err_probe(&pdev->dev, ret, "attaching serdev driver\n");
goto out_serdev_device_remove;
}
/* So that yt2_1380_fc_pdev_remove() can remove the serdev */
platform_set_drvdata(pdev, serdev);
return 0;
out_serdev_device_remove:
serdev_device_remove(serdev);
out_pinctrl_unregister_mappings:
pinctrl_unregister_mappings(yt2_1380_fc_pinctrl_map);
return ret;
}
static void yt2_1380_fc_pdev_remove(struct platform_device *pdev)
{
struct serdev_device *serdev = platform_get_drvdata(pdev);
serdev_device_remove(serdev);
pinctrl_unregister_mappings(yt2_1380_fc_pinctrl_map);
}
static struct platform_driver yt2_1380_fc_pdev_driver = {
.probe = yt2_1380_fc_pdev_probe,
.remove_new = yt2_1380_fc_pdev_remove,
.driver = {
.name = YT2_1380_FC_PDEV_NAME,
.probe_type = PROBE_PREFER_ASYNCHRONOUS,
},
};
static int __init yt2_1380_fc_module_init(void)
{
int ret;
/*
* serdev driver MUST be registered first because pdev driver calls
* device_driver_attach() on the serdev, serdev-driver pair.
*/
ret = serdev_device_driver_register(&yt2_1380_fc_serdev_driver);
if (ret)
return ret;
ret = platform_driver_register(&yt2_1380_fc_pdev_driver);
if (ret)
serdev_device_driver_unregister(&yt2_1380_fc_serdev_driver);
return ret;
}
module_init(yt2_1380_fc_module_init);
static void __exit yt2_1380_fc_module_exit(void)
{
platform_driver_unregister(&yt2_1380_fc_pdev_driver);
serdev_device_driver_unregister(&yt2_1380_fc_serdev_driver);
}
module_exit(yt2_1380_fc_module_exit);
MODULE_ALIAS("platform:" YT2_1380_FC_PDEV_NAME);
MODULE_DESCRIPTION("Lenovo Yoga Tablet 2 1380 fast charge driver");
MODULE_AUTHOR("Hans de Goede <[email protected]>");
MODULE_LICENSE("GPL");
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