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authorJohan Hovold <johan@kernel.org>2018-06-01 10:22:54 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-06-28 20:31:32 +0900
commit37768b054f2074f40de3cacd492baed482f5d9da (patch)
tree35d002a267bd214615d77631e16426dc9e65e41d /drivers/gnss/serial.c
parent98ddec80fdf1c3e6c594fe633e6fb2a8a0d699dd (diff)
downloadlinux-37768b054f2074f40de3cacd492baed482f5d9da.tar.gz
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>
Diffstat (limited to 'drivers/gnss/serial.c')
-rw-r--r--drivers/gnss/serial.c275
1 files changed, 275 insertions, 0 deletions
diff --git a/drivers/gnss/serial.c b/drivers/gnss/serial.c
new file mode 100644
index 000000000000..b01ba4438501
--- /dev/null
+++ b/drivers/gnss/serial.c
@@ -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");