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>
This commit is contained in:
Johan Hovold 2018-06-01 10:22:54 +02:00 committed by Greg Kroah-Hartman
parent 98ddec80fd
commit 37768b054f
4 changed files with 332 additions and 0 deletions

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@ -9,3 +9,10 @@ menuconfig GNSS
To compile this driver as a module, choose M here: the module will
be called gnss.
if GNSS
config GNSS_SERIAL
tristate
endif # GNSS

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@ -5,3 +5,6 @@
obj-$(CONFIG_GNSS) += gnss.o
gnss-y := core.o
obj-$(CONFIG_GNSS_SERIAL) += gnss-serial.o
gnss-serial-y := serial.o

275
drivers/gnss/serial.c Normal file
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@ -0,0 +1,275 @@
// SPDX-License-Identifier: GPL-2.0
/*
* Generic serial GNSS receiver driver
*
* Copyright (C) 2018 Johan Hovold <johan@kernel.org>
*/
#include <linux/errno.h>
#include <linux/gnss.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/pm.h>
#include <linux/pm_runtime.h>
#include <linux/serdev.h>
#include <linux/slab.h>
#include "serial.h"
static int gnss_serial_open(struct gnss_device *gdev)
{
struct gnss_serial *gserial = gnss_get_drvdata(gdev);
struct serdev_device *serdev = gserial->serdev;
int ret;
ret = serdev_device_open(serdev);
if (ret)
return ret;
serdev_device_set_baudrate(serdev, gserial->speed);
serdev_device_set_flow_control(serdev, false);
ret = pm_runtime_get_sync(&serdev->dev);
if (ret < 0) {
pm_runtime_put_noidle(&serdev->dev);
goto err_close;
}
return 0;
err_close:
serdev_device_close(serdev);
return ret;
}
static void gnss_serial_close(struct gnss_device *gdev)
{
struct gnss_serial *gserial = gnss_get_drvdata(gdev);
struct serdev_device *serdev = gserial->serdev;
serdev_device_close(serdev);
pm_runtime_put(&serdev->dev);
}
static int gnss_serial_write_raw(struct gnss_device *gdev,
const unsigned char *buf, size_t count)
{
struct gnss_serial *gserial = gnss_get_drvdata(gdev);
struct serdev_device *serdev = gserial->serdev;
int ret;
/* write is only buffered synchronously */
ret = serdev_device_write(serdev, buf, count, 0);
if (ret < 0)
return ret;
/* FIXME: determine if interrupted? */
serdev_device_wait_until_sent(serdev, 0);
return count;
}
static const struct gnss_operations gnss_serial_gnss_ops = {
.open = gnss_serial_open,
.close = gnss_serial_close,
.write_raw = gnss_serial_write_raw,
};
static int gnss_serial_receive_buf(struct serdev_device *serdev,
const unsigned char *buf, size_t count)
{
struct gnss_serial *gserial = serdev_device_get_drvdata(serdev);
struct gnss_device *gdev = gserial->gdev;
return gnss_insert_raw(gdev, buf, count);
}
static const struct serdev_device_ops gnss_serial_serdev_ops = {
.receive_buf = gnss_serial_receive_buf,
.write_wakeup = serdev_device_write_wakeup,
};
static int gnss_serial_set_power(struct gnss_serial *gserial,
enum gnss_serial_pm_state state)
{
if (!gserial->ops || !gserial->ops->set_power)
return 0;
return gserial->ops->set_power(gserial, state);
}
/*
* FIXME: need to provide subdriver defaults or separate dt parsing from
* allocation.
*/
static int gnss_serial_parse_dt(struct serdev_device *serdev)
{
struct gnss_serial *gserial = serdev_device_get_drvdata(serdev);
struct device_node *node = serdev->dev.of_node;
u32 speed = 4800;
of_property_read_u32(node, "current-speed", &speed);
gserial->speed = speed;
return 0;
}
struct gnss_serial *gnss_serial_allocate(struct serdev_device *serdev,
size_t data_size)
{
struct gnss_serial *gserial;
struct gnss_device *gdev;
int ret;
gserial = kzalloc(sizeof(*gserial) + data_size, GFP_KERNEL);
if (!gserial)
return ERR_PTR(-ENOMEM);
gdev = gnss_allocate_device(&serdev->dev);
if (!gdev) {
ret = -ENOMEM;
goto err_free_gserial;
}
gdev->ops = &gnss_serial_gnss_ops;
gnss_set_drvdata(gdev, gserial);
gserial->serdev = serdev;
gserial->gdev = gdev;
serdev_device_set_drvdata(serdev, gserial);
serdev_device_set_client_ops(serdev, &gnss_serial_serdev_ops);
ret = gnss_serial_parse_dt(serdev);
if (ret)
goto err_put_device;
return gserial;
err_put_device:
gnss_put_device(gserial->gdev);
err_free_gserial:
kfree(gserial);
return ERR_PTR(ret);
}
EXPORT_SYMBOL_GPL(gnss_serial_allocate);
void gnss_serial_free(struct gnss_serial *gserial)
{
gnss_put_device(gserial->gdev);
kfree(gserial);
};
EXPORT_SYMBOL_GPL(gnss_serial_free);
int gnss_serial_register(struct gnss_serial *gserial)
{
struct serdev_device *serdev = gserial->serdev;
int ret;
if (IS_ENABLED(CONFIG_PM)) {
pm_runtime_enable(&serdev->dev);
} else {
ret = gnss_serial_set_power(gserial, GNSS_SERIAL_ACTIVE);
if (ret < 0)
return ret;
}
ret = gnss_register_device(gserial->gdev);
if (ret)
goto err_disable_rpm;
return 0;
err_disable_rpm:
if (IS_ENABLED(CONFIG_PM))
pm_runtime_disable(&serdev->dev);
else
gnss_serial_set_power(gserial, GNSS_SERIAL_OFF);
return ret;
}
EXPORT_SYMBOL_GPL(gnss_serial_register);
void gnss_serial_deregister(struct gnss_serial *gserial)
{
struct serdev_device *serdev = gserial->serdev;
gnss_deregister_device(gserial->gdev);
if (IS_ENABLED(CONFIG_PM))
pm_runtime_disable(&serdev->dev);
else
gnss_serial_set_power(gserial, GNSS_SERIAL_OFF);
}
EXPORT_SYMBOL_GPL(gnss_serial_deregister);
#ifdef CONFIG_PM
static int gnss_serial_runtime_suspend(struct device *dev)
{
struct gnss_serial *gserial = dev_get_drvdata(dev);
return gnss_serial_set_power(gserial, GNSS_SERIAL_STANDBY);
}
static int gnss_serial_runtime_resume(struct device *dev)
{
struct gnss_serial *gserial = dev_get_drvdata(dev);
return gnss_serial_set_power(gserial, GNSS_SERIAL_ACTIVE);
}
#endif /* CONFIG_PM */
static int gnss_serial_prepare(struct device *dev)
{
if (pm_runtime_suspended(dev))
return 1;
return 0;
}
#ifdef CONFIG_PM_SLEEP
static int gnss_serial_suspend(struct device *dev)
{
struct gnss_serial *gserial = dev_get_drvdata(dev);
int ret = 0;
/*
* FIXME: serdev currently lacks support for managing the underlying
* device's wakeup settings. A workaround would be to close the serdev
* device here if it is open.
*/
if (!pm_runtime_suspended(dev))
ret = gnss_serial_set_power(gserial, GNSS_SERIAL_STANDBY);
return ret;
}
static int gnss_serial_resume(struct device *dev)
{
struct gnss_serial *gserial = dev_get_drvdata(dev);
int ret = 0;
if (!pm_runtime_suspended(dev))
ret = gnss_serial_set_power(gserial, GNSS_SERIAL_ACTIVE);
return ret;
}
#endif /* CONFIG_PM_SLEEP */
const struct dev_pm_ops gnss_serial_pm_ops = {
.prepare = gnss_serial_prepare,
SET_SYSTEM_SLEEP_PM_OPS(gnss_serial_suspend, gnss_serial_resume)
SET_RUNTIME_PM_OPS(gnss_serial_runtime_suspend, gnss_serial_runtime_resume, NULL)
};
EXPORT_SYMBOL_GPL(gnss_serial_pm_ops);
MODULE_AUTHOR("Johan Hovold <johan@kernel.org>");
MODULE_DESCRIPTION("Generic serial GNSS receiver driver");
MODULE_LICENSE("GPL v2");

47
drivers/gnss/serial.h Normal file
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@ -0,0 +1,47 @@
/* SPDX-License-Identifier: GPL-2.0 */
/*
* Generic serial GNSS receiver driver
*
* Copyright (C) 2018 Johan Hovold <johan@kernel.org>
*/
#ifndef _LINUX_GNSS_SERIAL_H
#define _LINUX_GNSS_SERIAL_H
#include <asm/termbits.h>
#include <linux/pm.h>
struct gnss_serial {
struct serdev_device *serdev;
struct gnss_device *gdev;
speed_t speed;
const struct gnss_serial_ops *ops;
unsigned long drvdata[0];
};
enum gnss_serial_pm_state {
GNSS_SERIAL_OFF,
GNSS_SERIAL_ACTIVE,
GNSS_SERIAL_STANDBY,
};
struct gnss_serial_ops {
int (*set_power)(struct gnss_serial *gserial,
enum gnss_serial_pm_state state);
};
extern const struct dev_pm_ops gnss_serial_pm_ops;
struct gnss_serial *gnss_serial_allocate(struct serdev_device *gserial,
size_t data_size);
void gnss_serial_free(struct gnss_serial *gserial);
int gnss_serial_register(struct gnss_serial *gserial);
void gnss_serial_deregister(struct gnss_serial *gserial);
static inline void *gnss_serial_get_drvdata(struct gnss_serial *gserial)
{
return gserial->drvdata;
}
#endif /* _LINUX_GNSS_SERIAL_H */