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// SPDX-License-Identifier: GPL-2.0
/*
* Bluetooth low power control via GPIO
*
* Copyright 2015-2020 Google LLC.
*/
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/property.h>
#include <linux/rfkill.h>
struct nitrous_bt_lpm {
struct gpio_desc *gpio_dev_wake; /* Host -> Dev WAKE GPIO */
struct gpio_desc *gpio_host_wake; /* Dev -> Host WAKE GPIO */
struct gpio_desc *gpio_power; /* GPIO to control power */
int wake_polarity; /* 0: active low; 1: active high */
struct device *dev;
struct rfkill *rfkill;
bool rfkill_blocked; /* blocked: OFF; not blocked: ON */
};
/*
* Set BT power on/off (blocked is true: OFF; blocked is false: ON)
*/
static int nitrous_rfkill_set_power(void *data, bool blocked)
{
struct nitrous_bt_lpm *lpm = data;
if (!lpm) {
pr_err("[BT] %s: missing lpm\n", __func__);
return -EINVAL;
}
pr_info("[BT] %s: %s (blocked=%d)\n", __func__, blocked ? "off" : "on",
blocked);
if (blocked == lpm->rfkill_blocked) {
pr_info("[BT] %s(%s) already in requested state\n", __func__,
blocked ? "off" : "on");
return 0;
}
if (!blocked) {
/* Power up the BT chip. delay between consecutive toggles. */
pr_debug("[BT] REG_ON: Low");
gpiod_set_value_cansleep(lpm->gpio_power, false);
msleep(30);
pr_debug("[BT] REG_ON: High");
gpiod_set_value_cansleep(lpm->gpio_power, true);
pr_debug("[BT] DEV_WAKE: High");
gpiod_set_value_cansleep(lpm->gpio_dev_wake, true);
} else {
pr_debug("[BT] DEV_WAKE: Low");
gpiod_set_value_cansleep(lpm->gpio_dev_wake, false);
/* Power down the BT chip */
pr_debug("[BT] REG_ON: Low");
gpiod_set_value_cansleep(lpm->gpio_power, false);
}
lpm->rfkill_blocked = blocked;
return 0;
}
static const struct rfkill_ops nitrous_rfkill_ops = {
.set_block = nitrous_rfkill_set_power,
};
static int nitrous_rfkill_init(struct nitrous_bt_lpm *lpm)
{
int rc;
lpm->gpio_power = devm_gpiod_get_optional(lpm->dev, "shutdown", GPIOD_OUT_LOW);
if (IS_ERR(lpm->gpio_power))
return PTR_ERR(lpm->gpio_power);
lpm->rfkill = rfkill_alloc(
"nitrous_bluetooth",
lpm->dev,
RFKILL_TYPE_BLUETOOTH,
&nitrous_rfkill_ops,
lpm
);
if (unlikely(!lpm->rfkill))
return -ENOMEM;
/* Make sure rfkill core is initialized to be blocked initially. */
rfkill_init_sw_state(lpm->rfkill, true);
rc = rfkill_register(lpm->rfkill);
if (unlikely(rc))
goto err_rfkill_register;
/* Power off chip at startup. */
nitrous_rfkill_set_power(lpm, true);
return 0;
err_rfkill_register:
rfkill_destroy(lpm->rfkill);
lpm->rfkill = NULL;
return rc;
}
static void nitrous_rfkill_cleanup(struct nitrous_bt_lpm *lpm)
{
nitrous_rfkill_set_power(lpm, true);
rfkill_unregister(lpm->rfkill);
rfkill_destroy(lpm->rfkill);
lpm->rfkill = NULL;
}
static int nitrous_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct nitrous_bt_lpm *lpm;
int rc = 0;
pr_debug("[BT] %s\n", __func__);
lpm = devm_kzalloc(dev, sizeof(struct nitrous_bt_lpm), GFP_KERNEL);
if (!lpm)
return -ENOMEM;
lpm->dev = dev;
if (device_property_read_u32(dev, "wake-polarity", &lpm->wake_polarity)) {
pr_warn("[BT] Wake polarity not in dev tree\n");
lpm->wake_polarity = 1;
}
lpm->gpio_dev_wake = devm_gpiod_get_optional(dev, "device-wakeup", GPIOD_OUT_LOW);
if (IS_ERR(lpm->gpio_dev_wake))
return PTR_ERR(lpm->gpio_dev_wake);
lpm->gpio_host_wake = devm_gpiod_get_optional(dev, "host-wakeup", GPIOD_IN);
if (IS_ERR(lpm->gpio_host_wake))
return PTR_ERR(lpm->gpio_host_wake);
rc = nitrous_rfkill_init(lpm);
if (unlikely(rc))
goto err_rfkill_init;
platform_set_drvdata(pdev, lpm);
return rc;
err_rfkill_init:
nitrous_rfkill_cleanup(lpm);
devm_kfree(dev, lpm);
return rc;
}
static int nitrous_remove(struct platform_device *pdev)
{
struct nitrous_bt_lpm *lpm = platform_get_drvdata(pdev);
if (!lpm) {
pr_err("[BT] %s: missing lpm\n", __func__);
return -EINVAL;
}
nitrous_rfkill_cleanup(lpm);
devm_kfree(&pdev->dev, lpm);
return 0;
}
static struct of_device_id nitrous_match_table[] = {
{ .compatible = "goog,nitrous" },
{}
};
static struct platform_driver nitrous_platform_driver = {
.probe = nitrous_probe,
.remove = nitrous_remove,
.driver = {
.name = "nitrous_bluetooth",
.owner = THIS_MODULE,
.of_match_table = nitrous_match_table,
.pm = NULL,
},
};
static int __init nitrous_init(void)
{
return platform_driver_register(&nitrous_platform_driver);
}
static void __exit nitrous_exit(void)
{
platform_driver_unregister(&nitrous_platform_driver);
}
module_init(nitrous_init);
module_exit(nitrous_exit);
MODULE_DESCRIPTION("Nitrous Oxide Driver for Bluetooth");
MODULE_AUTHOR("Google");
MODULE_LICENSE("GPL");
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