gnss: add generic serial driver
Add a generic serial GNSS driver (library) which provides a common implementation for the gnss interface and power management (runtime and system suspend). This allows GNSS drivers for specific chip to be implemented by simply providing a set_power() callback to handle three states: ACTIVE, STANDBY and OFF. Signed-off-by: Johan Hovold <johan@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>hifive-unleashed-5.1
Johan Hovold
Greg Kroah-Hartman
parent
98ddec80fd
commit
37768b054f
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@ -9,3 +9,10 @@ menuconfig GNSS
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To compile this driver as a module, choose M here: the module will
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be called gnss.
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if GNSS
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config GNSS_SERIAL
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tristate
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endif # GNSS
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@ -5,3 +5,6 @@
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obj-$(CONFIG_GNSS) += gnss.o
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gnss-y := core.o
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obj-$(CONFIG_GNSS_SERIAL) += gnss-serial.o
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gnss-serial-y := serial.o
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@ -0,0 +1,275 @@
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// SPDX-License-Identifier: GPL-2.0
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/*
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* Generic serial GNSS receiver driver
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*
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* Copyright (C) 2018 Johan Hovold <johan@kernel.org>
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*/
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#include <linux/errno.h>
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#include <linux/gnss.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/pm.h>
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#include <linux/pm_runtime.h>
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#include <linux/serdev.h>
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#include <linux/slab.h>
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#include "serial.h"
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static int gnss_serial_open(struct gnss_device *gdev)
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{
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struct gnss_serial *gserial = gnss_get_drvdata(gdev);
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struct serdev_device *serdev = gserial->serdev;
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int ret;
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ret = serdev_device_open(serdev);
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if (ret)
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return ret;
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serdev_device_set_baudrate(serdev, gserial->speed);
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serdev_device_set_flow_control(serdev, false);
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ret = pm_runtime_get_sync(&serdev->dev);
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if (ret < 0) {
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pm_runtime_put_noidle(&serdev->dev);
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goto err_close;
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}
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return 0;
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err_close:
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serdev_device_close(serdev);
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return ret;
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}
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static void gnss_serial_close(struct gnss_device *gdev)
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{
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struct gnss_serial *gserial = gnss_get_drvdata(gdev);
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struct serdev_device *serdev = gserial->serdev;
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serdev_device_close(serdev);
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pm_runtime_put(&serdev->dev);
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}
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static int gnss_serial_write_raw(struct gnss_device *gdev,
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const unsigned char *buf, size_t count)
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{
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struct gnss_serial *gserial = gnss_get_drvdata(gdev);
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struct serdev_device *serdev = gserial->serdev;
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int ret;
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/* write is only buffered synchronously */
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ret = serdev_device_write(serdev, buf, count, 0);
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if (ret < 0)
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return ret;
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/* FIXME: determine if interrupted? */
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serdev_device_wait_until_sent(serdev, 0);
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return count;
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}
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static const struct gnss_operations gnss_serial_gnss_ops = {
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.open = gnss_serial_open,
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.close = gnss_serial_close,
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.write_raw = gnss_serial_write_raw,
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};
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static int gnss_serial_receive_buf(struct serdev_device *serdev,
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const unsigned char *buf, size_t count)
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{
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struct gnss_serial *gserial = serdev_device_get_drvdata(serdev);
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struct gnss_device *gdev = gserial->gdev;
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return gnss_insert_raw(gdev, buf, count);
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}
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static const struct serdev_device_ops gnss_serial_serdev_ops = {
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.receive_buf = gnss_serial_receive_buf,
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.write_wakeup = serdev_device_write_wakeup,
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};
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static int gnss_serial_set_power(struct gnss_serial *gserial,
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enum gnss_serial_pm_state state)
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{
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if (!gserial->ops || !gserial->ops->set_power)
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return 0;
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return gserial->ops->set_power(gserial, state);
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}
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/*
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* FIXME: need to provide subdriver defaults or separate dt parsing from
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* allocation.
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*/
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static int gnss_serial_parse_dt(struct serdev_device *serdev)
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{
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struct gnss_serial *gserial = serdev_device_get_drvdata(serdev);
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struct device_node *node = serdev->dev.of_node;
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u32 speed = 4800;
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of_property_read_u32(node, "current-speed", &speed);
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gserial->speed = speed;
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return 0;
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}
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struct gnss_serial *gnss_serial_allocate(struct serdev_device *serdev,
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size_t data_size)
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{
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struct gnss_serial *gserial;
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struct gnss_device *gdev;
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int ret;
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gserial = kzalloc(sizeof(*gserial) + data_size, GFP_KERNEL);
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if (!gserial)
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return ERR_PTR(-ENOMEM);
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gdev = gnss_allocate_device(&serdev->dev);
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if (!gdev) {
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ret = -ENOMEM;
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goto err_free_gserial;
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}
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gdev->ops = &gnss_serial_gnss_ops;
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gnss_set_drvdata(gdev, gserial);
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gserial->serdev = serdev;
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gserial->gdev = gdev;
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serdev_device_set_drvdata(serdev, gserial);
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serdev_device_set_client_ops(serdev, &gnss_serial_serdev_ops);
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ret = gnss_serial_parse_dt(serdev);
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if (ret)
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goto err_put_device;
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return gserial;
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err_put_device:
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gnss_put_device(gserial->gdev);
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err_free_gserial:
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kfree(gserial);
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return ERR_PTR(ret);
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}
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EXPORT_SYMBOL_GPL(gnss_serial_allocate);
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void gnss_serial_free(struct gnss_serial *gserial)
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{
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gnss_put_device(gserial->gdev);
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kfree(gserial);
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};
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EXPORT_SYMBOL_GPL(gnss_serial_free);
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int gnss_serial_register(struct gnss_serial *gserial)
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{
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struct serdev_device *serdev = gserial->serdev;
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int ret;
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if (IS_ENABLED(CONFIG_PM)) {
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pm_runtime_enable(&serdev->dev);
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} else {
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ret = gnss_serial_set_power(gserial, GNSS_SERIAL_ACTIVE);
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if (ret < 0)
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return ret;
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}
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ret = gnss_register_device(gserial->gdev);
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if (ret)
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goto err_disable_rpm;
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return 0;
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err_disable_rpm:
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if (IS_ENABLED(CONFIG_PM))
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pm_runtime_disable(&serdev->dev);
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else
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gnss_serial_set_power(gserial, GNSS_SERIAL_OFF);
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return ret;
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}
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EXPORT_SYMBOL_GPL(gnss_serial_register);
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void gnss_serial_deregister(struct gnss_serial *gserial)
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{
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struct serdev_device *serdev = gserial->serdev;
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gnss_deregister_device(gserial->gdev);
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if (IS_ENABLED(CONFIG_PM))
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pm_runtime_disable(&serdev->dev);
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else
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gnss_serial_set_power(gserial, GNSS_SERIAL_OFF);
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}
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EXPORT_SYMBOL_GPL(gnss_serial_deregister);
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#ifdef CONFIG_PM
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static int gnss_serial_runtime_suspend(struct device *dev)
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{
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struct gnss_serial *gserial = dev_get_drvdata(dev);
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return gnss_serial_set_power(gserial, GNSS_SERIAL_STANDBY);
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}
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static int gnss_serial_runtime_resume(struct device *dev)
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{
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struct gnss_serial *gserial = dev_get_drvdata(dev);
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return gnss_serial_set_power(gserial, GNSS_SERIAL_ACTIVE);
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}
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#endif /* CONFIG_PM */
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static int gnss_serial_prepare(struct device *dev)
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{
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if (pm_runtime_suspended(dev))
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return 1;
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return 0;
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}
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#ifdef CONFIG_PM_SLEEP
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static int gnss_serial_suspend(struct device *dev)
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{
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struct gnss_serial *gserial = dev_get_drvdata(dev);
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int ret = 0;
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/*
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* FIXME: serdev currently lacks support for managing the underlying
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* device's wakeup settings. A workaround would be to close the serdev
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* device here if it is open.
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*/
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if (!pm_runtime_suspended(dev))
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ret = gnss_serial_set_power(gserial, GNSS_SERIAL_STANDBY);
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return ret;
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}
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static int gnss_serial_resume(struct device *dev)
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{
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struct gnss_serial *gserial = dev_get_drvdata(dev);
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int ret = 0;
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if (!pm_runtime_suspended(dev))
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ret = gnss_serial_set_power(gserial, GNSS_SERIAL_ACTIVE);
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return ret;
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}
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#endif /* CONFIG_PM_SLEEP */
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const struct dev_pm_ops gnss_serial_pm_ops = {
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.prepare = gnss_serial_prepare,
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SET_SYSTEM_SLEEP_PM_OPS(gnss_serial_suspend, gnss_serial_resume)
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SET_RUNTIME_PM_OPS(gnss_serial_runtime_suspend, gnss_serial_runtime_resume, NULL)
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};
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EXPORT_SYMBOL_GPL(gnss_serial_pm_ops);
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MODULE_AUTHOR("Johan Hovold <johan@kernel.org>");
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MODULE_DESCRIPTION("Generic serial GNSS receiver driver");
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MODULE_LICENSE("GPL v2");
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@ -0,0 +1,47 @@
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/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Generic serial GNSS receiver driver
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*
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* Copyright (C) 2018 Johan Hovold <johan@kernel.org>
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*/
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#ifndef _LINUX_GNSS_SERIAL_H
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#define _LINUX_GNSS_SERIAL_H
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#include <asm/termbits.h>
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#include <linux/pm.h>
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struct gnss_serial {
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struct serdev_device *serdev;
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struct gnss_device *gdev;
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speed_t speed;
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const struct gnss_serial_ops *ops;
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unsigned long drvdata[0];
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};
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enum gnss_serial_pm_state {
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GNSS_SERIAL_OFF,
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GNSS_SERIAL_ACTIVE,
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GNSS_SERIAL_STANDBY,
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};
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struct gnss_serial_ops {
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int (*set_power)(struct gnss_serial *gserial,
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enum gnss_serial_pm_state state);
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};
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extern const struct dev_pm_ops gnss_serial_pm_ops;
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struct gnss_serial *gnss_serial_allocate(struct serdev_device *gserial,
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size_t data_size);
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void gnss_serial_free(struct gnss_serial *gserial);
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int gnss_serial_register(struct gnss_serial *gserial);
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void gnss_serial_deregister(struct gnss_serial *gserial);
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static inline void *gnss_serial_get_drvdata(struct gnss_serial *gserial)
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{
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return gserial->drvdata;
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}
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#endif /* _LINUX_GNSS_SERIAL_H */
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