[RFC,2/3] misc: Add w2sg0004 (gps receiver) power control driver

Commit Message

H. Nikolaus Schaller May 21, 2017, 10:44 a.m. UTC

Add driver for Wi2Wi W2SG0004/84 GPS module connected through uart.

Use serdev API hooks to monitor and forward the UART traffic to /dev/BTn
and turn on/off the module. It also detects if the module is turned on (sends data)
but should be off, e.g. if it was already turned on during boot or power-on-reset.

Additionally, rfkill block/unblock can be used to control an external LNA
(and power down the module if not needed).

The driver concept is based on code developed by NeilBrown <[e-mail]>
but simplified and adapted to use the new serdev API introduced in 4.11.

Signed-off-by: H. Nikolaus Schaller <[e-mail]>
---
 .../devicetree/bindings/misc/wi2wi,w2sg0004.txt    |  20 +
 .../devicetree/bindings/vendor-prefixes.txt        |   1 +
 drivers/misc/Kconfig                               |  16 +
 drivers/misc/Makefile                              |   1 +
 drivers/misc/w2sg0004.c                            | 646 +++++++++++++++++++++
 include/linux/w2sg0004.h                           |  27 +
 6 files changed, 711 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt
 create mode 100644 drivers/misc/w2sg0004.c
 create mode 100644 include/linux/w2sg0004.h

Comments

H. Nikolaus Schaller May 21, 2017, 10:48 a.m. UTC | #1

> Am 21.05.2017 um 12:44 schrieb H. Nikolaus Schaller <[e-mail]>:
> 
> Add driver for Wi2Wi W2SG0004/84 GPS module connected through uart.
> 
> Use serdev API hooks to monitor and forward the UART traffic to /dev/BTn

s/BTn/GPSn/

> and turn on/off the module. It also detects if the module is turned on (sends data)
> but should be off, e.g. if it was already turned on during boot or power-on-reset.
> 
> Additionally, rfkill block/unblock can be used to control an external LNA
> (and power down the module if not needed).
> 
> The driver concept is based on code developed by NeilBrown <[e-mail]>
> but simplified and adapted to use the new serdev API introduced in 4.11.
> 
> Signed-off-by: H. Nikolaus Schaller <[e-mail]>
> ---
> .../devicetree/bindings/misc/wi2wi,w2sg0004.txt    |  20 +
> .../devicetree/bindings/vendor-prefixes.txt        |   1 +
> drivers/misc/Kconfig                               |  16 +
> drivers/misc/Makefile                              |   1 +
> drivers/misc/w2sg0004.c                            | 646 +++++++++++++++++++++
> include/linux/w2sg0004.h                           |  27 +
> 6 files changed, 711 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt
> create mode 100644 drivers/misc/w2sg0004.c
> create mode 100644 include/linux/w2sg0004.h
> 
> diff --git a/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt b/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt
> new file mode 100644
> index 000000000000..b7125c7a598c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt
> @@ -0,0 +1,20 @@
> +Wi2Wi GPS module connected through UART
> +
> +Should be a subnode of the SoC UART it is connected to (serdev).
> +
> +Required properties:
> +- compatible:	wi2wi,w2sg0004 or wi2wi,w2sg0084
> +- on-off-gpio:	the GPIO that controls the module's on-off toggle input
> +
> +Optional properties:
> +- lna-suppy:	an (optional) LNA regulator that is enabled together with the GPS receiver
> +
> +Example:
> +
> +&uart2 {
> +	gps: w2sg0004 {
> +		compatible = "wi2wi,w2sg0004";
> +		lna-supply = <&vsim>;   /* LNA regulator */
> +		on-off-gpios = <&gpio5 17 GPIO_ACTIVE_HIGH>;    /* GPIO_145: trigger for turning on/off w2sg0004 */
> +        };
> +};
> diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
> index c03d20140366..c56b3181b266 100644
> --- a/Documentation/devicetree/bindings/vendor-prefixes.txt
> +++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
> @@ -345,6 +345,7 @@ voipac	Voipac Technologies s.r.o.
> wd	Western Digital Corp.
> wetek	WeTek Electronics, limited.
> wexler	Wexler
> +wi2wi	Wi2Wi, Inc.
> winbond Winbond Electronics corp.
> winstar	Winstar Display Corp.
> wlf	Wolfson Microelectronics
> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
> index 60f876b03586..7f97ef8fb6cd 100644
> --- a/drivers/misc/Kconfig
> +++ b/drivers/misc/Kconfig
> @@ -509,4 +509,20 @@ source "drivers/misc/mic/Kconfig"
> source "drivers/misc/genwqe/Kconfig"
> source "drivers/misc/echo/Kconfig"
> source "drivers/misc/cxl/Kconfig"
> +
> +config W2SG0004
> +	tristate "W2SG00x4 on/off control"
> +	depends on GPIOLIB && SERIAL_DEV_BUS
> +	help
> +          Enable on/off control of W2SG00x4 GPS moduled connected
> +	  to some SoC UART to allow powering up/down if the /dev/ttyGPSn
> +	  is opened/closed.
> +	  It also provides a rfkill gps name to control the LNA power.
> +
> +config W2SG0004_DEBUG
> +	bool "W2SG0004 on/off debugging"
> +	depends on W2SG0004
> +	help
> +	  Enable driver debugging mode of W2SG0004 GPS.
> +
> endmenu
> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
> index 81ef3e67acc9..0e88e06e5ee0 100644
> --- a/drivers/misc/Makefile
> +++ b/drivers/misc/Makefile
> @@ -50,6 +50,7 @@ obj-$(CONFIG_SRAM_EXEC)		+= sram-exec.o
> obj-y				+= mic/
> obj-$(CONFIG_GENWQE)		+= genwqe/
> obj-$(CONFIG_ECHO)		+= echo/
> +obj-$(CONFIG_W2SG0004)		+= w2sg0004.o
> obj-$(CONFIG_VEXPRESS_SYSCFG)	+= vexpress-syscfg.o
> obj-$(CONFIG_CXL_BASE)		+= cxl/
> obj-$(CONFIG_ASPEED_LPC_CTRL)	+= aspeed-lpc-ctrl.o
> diff --git a/drivers/misc/w2sg0004.c b/drivers/misc/w2sg0004.c
> new file mode 100644
> index 000000000000..1b335317c8ac
> --- /dev/null
> +++ b/drivers/misc/w2sg0004.c
> @@ -0,0 +1,646 @@
> +/*
> + * w2sg0004.c
> + * Driver for power controlling the w2sg0004/w2sg0084 GPS receiver.
> + *
> + * This receiver has an ON/OFF pin which must be toggled to
> + * turn the device 'on' of 'off'.  A high->low->high toggle
> + * will switch the device on if it is off, and off if it is on.
> + *
> + * To enable receiving on/off requests we register with the
> + * UART power management notifications.
> + *
> + * It is not possible to directly detect the state of the device.
> + * However when it is on it will send characters on a UART line
> + * regularly.
> + *
> + * To detect that the power state is out of sync (e.g. if GPS
> + * was enabled before a reboot), we register for UART data received
> + * notifications.
> + *
> + * In addition we register as a rfkill client so that we can
> + * control the LNA power.
> + *
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_gpio.h>
> +#include <linux/platform_device.h>
> +#include <linux/rfkill.h>
> +#include <linux/serdev.h>
> +#include <linux/sched.h>
> +#include <linux/slab.h>
> +#include <linux/tty.h>
> +#include <linux/tty_flip.h>
> +#include <linux/w2sg0004.h>
> +#include <linux/workqueue.h>
> +
> +#ifdef CONFIG_W2SG0004_DEBUG	// not for upstreaming
> +#undef pr_debug
> +#define pr_debug printk
> +#endif
> +
> +/*
> + * There seems to be restrictions on how quickly we can toggle the
> + * on/off line.  data sheets says "two rtc ticks", whatever that means.
> + * If we do it too soon it doesn't work.
> + * So we have a state machine which uses the common work queue to ensure
> + * clean transitions.
> + * When a change is requested we record that request and only act on it
> + * once the previous change has completed.
> + * A change involves a 10ms low pulse, and a 990ms raised level, so only
> + * one change per second.
> + */
> +
> +enum w2sg_state {
> +	W2SG_IDLE,	/* is not changing state */
> +	W2SG_PULSE,	/* activate on/off impulse */
> +	W2SG_NOPULSE	/* deactivate on/off impulse */
> +};
> +
> +struct w2sg_data {
> +	struct		rfkill *rf_kill;
> +	struct		regulator *lna_regulator;
> +	int		lna_blocked;	/* rfkill block gps active */
> +	int		lna_is_off;	/* LNA is currently off */
> +	int		is_on;		/* current state (0/1) */
> +	unsigned long	last_toggle;
> +	unsigned long	backoff;	/* time to wait since last_toggle */
> +	int		on_off_gpio;	/* the on-off gpio number */
> +	struct		serdev_device *uart;	/* the uart connected to the chip */
> +	struct		tty_driver *tty_drv;	/* this is the user space tty */
> +	struct		device *dev;	/* returned by tty_port_register_device() */
> +	struct		tty_port port;
> +	int		open_count;	/* how often we were opened */
> +	enum		w2sg_state state;
> +	int		requested;	/* requested state (0/1) */
> +	int		suspended;
> +	spinlock_t	lock;
> +	struct delayed_work work;
> +	int		discard_count;
> +};
> +
> +static struct w2sg_data *w2sg_by_minor[1];
> +
> +static int w2sg_set_lna_power(struct w2sg_data *data)
> +{
> +	int ret = 0;
> +	int off = data->suspended || !data->requested || data->lna_blocked;
> +
> +	pr_debug("%s: %s\n", __func__, off ? "off" : "on");
> +
> +	if (off != data->lna_is_off) {
> +		data->lna_is_off = off;
> +		if (!IS_ERR_OR_NULL(data->lna_regulator)) {
> +			if (off)
> +				regulator_disable(data->lna_regulator);
> +			else
> +				ret = regulator_enable(data->lna_regulator);
> +		}
> +	}
> +
> +	return ret;
> +}
> +
> +static void w2sg_set_power(void *pdata, int val)
> +{
> +	struct w2sg_data *data = (struct w2sg_data *) pdata;
> +
> +	pr_debug("%s to state=%d (requested=%d)\n", __func__, val, data->requested);
> +
> +	if (val && !data->requested) {
> +		data->requested = true;
> +	} else if (!val && data->requested) {
> +		data->backoff = HZ;
> +		data->requested = false;
> +	} else
> +		return;
> +
> +	pr_debug("w2sg00x4 scheduled for %d\n", data->requested);
> +
> +	if (!data->suspended)
> +		schedule_delayed_work(&data->work, 0);
> +}
> +
> +/* called each time data is received by the UART (i.e. sent by the w2sg0004) */
> +
> +static int w2sg_uart_receive_buf(struct serdev_device *serdev, const unsigned char *rxdata,
> +				size_t count)
> +{
> +	struct w2sg_data *data = (struct w2sg_data *) serdev_device_get_drvdata(serdev);
> +//	unsigned long flags;
> +
> +//	pr_debug("w2sg: %d characters\n", count);
> +
> +	if (!data->requested && !data->is_on) {
> +		/* we have received characters while the w2sg should have been be turned off */
> +		data->discard_count += count;
> +		if ((data->state == W2SG_IDLE) &&
> +		    time_after(jiffies,
> +		    data->last_toggle + data->backoff)) {
> +			/* Should be off by now, time to toggle again */
> +			pr_debug("w2sg00x4 has sent %d characters data although it should be off!\n", data->discard_count);
> +			data->discard_count = 0;
> +
> +			data->is_on = true;
> +			data->backoff *= 2;
> +//			spin_lock_irqsave(&data->lock, flags);
> +			if (!data->suspended)
> +				schedule_delayed_work(&data->work, 0);
> +//			spin_unlock_irqrestore(&data->lock, flags);
> +		}
> +	} else if (data->open_count > 0) {
> +		int n;
> +
> +//		pr_debug("w2sg00x4: push %d chars to tty port\n", count);
> +		n = tty_insert_flip_string(&data->port, rxdata, count);	/* pass to user-space */
> +		if (n != count)
> +			pr_debug("w2sg00x4: did loose %d characters\n", count - n);
> +		tty_flip_buffer_push(&data->port);
> +		return n;
> +	}
> +
> +	/* assume we have processed everything */
> +	return count;
> +}
> +
> +/* try to toggle the power state by sending a pulse to the on-off GPIO */
> +
> +static void toggle_work(struct work_struct *work)
> +{
> +	struct w2sg_data *data = container_of(work, struct w2sg_data,
> +					      work.work);
> +
> +	switch (data->state) {
> +	case W2SG_IDLE:
> +//		spin_lock_irq(&data->lock);
> +		if (data->requested == data->is_on) {
> +			spin_unlock_irq(&data->lock);
> +			return;
> +		}
> +//		spin_unlock_irq(&data->lock);
> +		w2sg_set_lna_power(data);	/* update LNA power state */
> +		gpio_set_value_cansleep(data->on_off_gpio, 0);
> +		data->state = W2SG_PULSE;
> +
> +		pr_debug("w2sg: power gpio ON\n");
> +
> +		schedule_delayed_work(&data->work,
> +				      msecs_to_jiffies(10));
> +		break;
> +
> +	case W2SG_PULSE:
> +		gpio_set_value_cansleep(data->on_off_gpio, 1);
> +		data->last_toggle = jiffies;
> +		data->state = W2SG_NOPULSE;
> +		data->is_on = !data->is_on;
> +
> +		pr_debug("w2sg: power gpio OFF\n");
> +
> +		schedule_delayed_work(&data->work,
> +				      msecs_to_jiffies(10));
> +		break;
> +
> +	case W2SG_NOPULSE:
> +		data->state = W2SG_IDLE;
> +		pr_debug("w2sg: idle\n");
> +
> +		break;
> +
> +	}
> +}
> +
> +static int w2sg_rfkill_set_block(void *pdata, bool blocked)
> +{
> +	struct w2sg_data *data = pdata;
> +
> +	pr_debug("%s: blocked: %d\n", __func__, blocked);
> +
> +	data->lna_blocked = blocked;
> +
> +	return w2sg_set_lna_power(data);
> +}
> +
> +static struct rfkill_ops w2sg0004_rfkill_ops = {
> +	.set_block = w2sg_rfkill_set_block,
> +};
> +
> +static struct serdev_device_ops serdev_ops = {
> +	.receive_buf = w2sg_uart_receive_buf,
> +#if 0
> +	.write_wakeup = w2sg_uart_wakeup,
> +#endif
> +};
> +
> +/*
> + * we are a man-in the middle between the user-space visible tty port
> + * and the serdev tty where the chip is connected.
> + * This allows us to recognise when the device should be powered on
> + * or off and handle the "false" state that data arrives while no
> + * users-space tty client exists.
> + */
> +
> +static struct w2sg_data *w2sg_get_by_minor(unsigned int minor)
> +{
> +	return w2sg_by_minor[minor];
> +}
> +
> +static int w2sg_tty_install(struct tty_driver *driver, struct tty_struct *tty)
> +{
> +	struct w2sg_data *data;
> +	int retval;
> +
> +	pr_debug("%s() tty = %p\n", __func__, tty);
> +
> +	data = w2sg_get_by_minor(tty->index);
> +	pr_debug("%s() data = %p\n", __func__, data);
> +
> +	if (!data)
> +		return -ENODEV;
> +
> +	retval = tty_standard_install(driver, tty);
> +	if (retval)
> +		goto error_init_termios;
> +
> +	tty->driver_data = data;
> +
> +	return 0;
> +
> +error_init_termios:
> +	tty_port_put(&data->port);
> +	return retval;
> +}
> +
> +static int w2sg_tty_open(struct tty_struct *tty, struct file *file)
> +{
> +	struct w2sg_data *data = tty->driver_data;
> +
> +	pr_debug("%s() data = %p open_count = ++%d\n", __func__, data, data->open_count);
> +//	val = (val & TIOCM_DTR) != 0;	/* DTR controls power on/off */
> +
> +	w2sg_set_power(data, ++data->open_count > 0);
> +
> +// we could/should return -Esomething if already open...
> +
> +	return tty_port_open(&data->port, tty, file);
> +}
> +
> +static void w2sg_tty_close(struct tty_struct *tty, struct file *file)
> +{
> +	struct w2sg_data *data = tty->driver_data;
> +
> +	pr_debug("%s()\n", __func__);
> +//	val = (val & TIOCM_DTR) != 0;	/* DTR controls power on/off */
> +	w2sg_set_power(data, --data->open_count > 0);
> +
> +	tty_port_close(&data->port, tty, file);
> +}
> +
> +static int w2sg_tty_write(struct tty_struct *tty,
> +		const unsigned char *buffer, int count)
> +{
> +	struct w2sg_data *data = tty->driver_data;
> +
> +	/* simply pass down to UART */
> +	return serdev_device_write_buf(data->uart, buffer, count);
> +}
> +
> +#if 0
> +static void w2sg_tty_tiocmget(...)
> +{
> +	int val;
> +
> +	pr_debug("%s(...,%x)\n", __func__, val);
> +	val = (val & TIOCM_DTR) != 0;	/* DTR controls power on/off */
> +	w2sg_set_power((struct w2sg_data *) pdata, val);
> +}
> +#endif
> +
> +
> +static const struct tty_operations w2sg_serial_ops = {
> +	.install = w2sg_tty_install,
> +	.open = w2sg_tty_open,
> +	.close = w2sg_tty_close,
> +	.write = w2sg_tty_write,
> +#if 0
> +	.write_room = w2sg_tty_write_room,
> +	.cleanup = w2sg_tty_cleanup,
> +	.ioctl = w2sg_tty_ioctl,
> +	.set_termios = w2sg_tty_set_termios,
> +	.chars_in_buffer = w2sg_tty_chars_in_buffer,
> +	.tiocmget = w2sg_tty_tiocmget,
> +	.tiocmset = w2sg_tty_tiocmset,
> +	.get_icount = w2sg_tty_get_count,
> +	.unthrottle = w2sg_tty_unthrottle
> +#endif
> +};
> +
> +static const struct tty_port_operations w2sg_port_ops = {
> +};
> +
> +static int w2sg_probe(struct serdev_device *serdev)
> +{
> +	struct w2sg_pdata *pdata = NULL;
> +	struct w2sg_data *data;
> +	struct rfkill *rf_kill;
> +	int err;
> +	int minor;
> +
> +	pr_debug("%s()\n", __func__);
> +
> +	minor = 0;
> +	if (w2sg_by_minor[minor]) {
> +		pr_err("w2sg minor is already in use!\n");
> +		return -ENODEV;
> +	}
> +
> +// can be simplified if we require OF
> +
> +	if (serdev->dev.of_node) {
> +		struct device *dev = &serdev->dev;
> +		enum of_gpio_flags flags;
> +
> +		pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
> +		if (!pdata)
> +			return -ENOMEM;
> +
> +		pdata->on_off_gpio = of_get_named_gpio_flags(dev->of_node,
> +							     "on-off-gpios", 0,
> +							     &flags);
> +
> +		if (pdata->on_off_gpio == -EPROBE_DEFER)
> +			return -EPROBE_DEFER;	/* defer until we have all gpios */
> +
> +		pdata->lna_regulator = devm_regulator_get_optional(dev, "lna");
> +// shouldn't we defer probing as well???
> +
> +		pr_debug("%s() lna_regulator = %p\n", __func__, pdata->lna_regulator);
> +
> +		serdev->dev.platform_data = pdata;
> +	}
> +
> +	data = devm_kzalloc(&serdev->dev, sizeof(*data), GFP_KERNEL);
> +	if (data == NULL)
> +		return -ENOMEM;
> +
> +	w2sg_by_minor[minor] = data;
> +
> +#if 1
> +	pr_debug("w2sg serdev_device_set_drvdata\n");
> +#endif
> +	serdev_device_set_drvdata(serdev, data);
> +
> +	data->lna_regulator = pdata->lna_regulator;
> +	data->lna_blocked = true;
> +	data->lna_is_off = true;
> +
> +	data->on_off_gpio = pdata->on_off_gpio;
> +
> +	data->is_on = false;
> +	data->requested = false;
> +	data->state = W2SG_IDLE;
> +	data->last_toggle = jiffies;
> +	data->backoff = HZ;
> +
> +	data->uart = serdev;
> +
> +	INIT_DELAYED_WORK(&data->work, toggle_work);
> +//	spin_lock_init(&data->lock);
> +
> +#if 1
> +	pr_debug("w2sg devm_gpio_request\n");
> +#endif
> +	err = devm_gpio_request(&serdev->dev, data->on_off_gpio, "w2sg0004-on-off");
> +	if (err < 0)
> +		goto out;
> +
> +	gpio_direction_output(data->on_off_gpio, false);
> +
> +	serdev_device_set_client_ops(data->uart, &serdev_ops);
> +	serdev_device_open(data->uart);
> +
> +	serdev_device_set_baudrate(data->uart, 9600);
> +	serdev_device_set_flow_control(data->uart, false);
> +
> +#if 1
> +	pr_debug("w2sg rfkill_alloc\n");
> +#endif
> +	rf_kill = rfkill_alloc("GPS", &serdev->dev, RFKILL_TYPE_GPS,
> +				&w2sg0004_rfkill_ops, data);
> +	if (rf_kill == NULL) {
> +		err = -ENOMEM;
> +		goto err_rfkill;
> +	}
> +
> +#if 1
> +	pr_debug("w2sg register rfkill\n");
> +#endif
> +	err = rfkill_register(rf_kill);
> +	if (err) {
> +		dev_err(&serdev->dev, "Cannot register rfkill device\n");
> +		goto err_rfkill;
> +	}
> +
> +	data->rf_kill = rf_kill;
> +
> +#if 1
> +	pr_debug("w2sg alloc_tty_driver\n");
> +#endif
> +	/* allocate the tty driver */
> +	data->tty_drv = alloc_tty_driver(1);
> +	if (!data->tty_drv)
> +		return -ENOMEM;
> +
> +	/* initialize the tty driver */
> +	data->tty_drv->owner = THIS_MODULE;
> +	data->tty_drv->driver_name = "w2sg0004";
> +	data->tty_drv->name = "ttyGPS";
> +	data->tty_drv->major = 0;
> +	data->tty_drv->minor_start = 0;
> +	data->tty_drv->type = TTY_DRIVER_TYPE_SERIAL;
> +	data->tty_drv->subtype = SERIAL_TYPE_NORMAL;
> +	data->tty_drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
> +	data->tty_drv->init_termios = tty_std_termios;
> +	data->tty_drv->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
> +	/*
> +	 * tty_termios_encode_baud_rate(&data->tty_drv->init_termios, 115200, 115200);
> +	 * w2sg_tty_termios(&data->tty_drv->init_termios);
> +	 */
> +	tty_set_operations(data->tty_drv, &w2sg_serial_ops);
> +
> +#if 1
> +	pr_debug("w2sg tty_register_driver\n");
> +#endif
> +	/* register the tty driver */
> +	err = tty_register_driver(data->tty_drv);
> +	if (err) {
> +		pr_err("%s - tty_register_driver failed(%d)\n",
> +			__func__, err);
> +		put_tty_driver(data->tty_drv);
> +		goto err_rfkill;
> +	}
> +
> +#if 1
> +	pr_debug("w2sg call tty_port_init\n");
> +#endif
> +	tty_port_init(&data->port);
> +	data->port.ops = &w2sg_port_ops;
> +
> +#if 1
> +	pr_debug("w2sg call tty_port_register_device\n");
> +#endif
> +/*
> + * FIXME: this appears to reenter this probe() function a second time
> + * which only fails because the gpio is already assigned
> + */
> +
> +	data->dev = tty_port_register_device(&data->port,
> +			data->tty_drv, minor, &serdev->dev);
> +
> +#if 1
> +	pr_debug("w2sg tty_port_register_device -> %p\n", data->dev);
> +	pr_debug("w2sg port.tty = %p\n", data->port.tty);
> +#endif
> +//	data->port.tty->driver_data = data;	/* make us known in tty_struct */
> +
> +	pr_debug("w2sg probed\n");
> +
> +#ifdef CONFIG_W2SG0004_DEBUG
> +	pr_debug("w2sg DEBUGGING MODE enabled\n");
> +	/* turn on for debugging rx notifications */
> +	pr_debug("w2sg power gpio ON\n");
> +	gpio_set_value_cansleep(data->on_off_gpio, 1);
> +	mdelay(100);
> +	pr_debug("w2sg power gpio OFF\n");
> +	gpio_set_value_cansleep(data->on_off_gpio, 0);
> +	mdelay(300);
> +#endif
> +
> +	/* keep off until user space requests the device */
> +	w2sg_set_power(data, false);
> +
> +#if 0	// more debugging - not for upstreaming
> +	w2sg_set_power(data, true);
> +#endif
> +
> +	return 0;
> +
> +err_rfkill:
> +	rfkill_destroy(rf_kill);
> +	serdev_device_close(data->uart);
> +out:
> +#if 0
> +	if (err == -EBUSY)
> +		err = -EPROBE_DEFER;
> +#endif
> +#if 1
> +	pr_debug("w2sg error %d\n", err);
> +#endif
> +	return err;
> +}
> +
> +static void w2sg_remove(struct serdev_device *serdev)
> +{
> +	struct w2sg_data *data = serdev_device_get_drvdata(serdev);
> +	int minor;
> +
> +	cancel_delayed_work_sync(&data->work);
> +
> +	/* what is the right sequence to avoid problems? */
> +	serdev_device_close(data->uart);
> +
> +	// get minor from searching for data == w2sg_by_minor[minor]
> +	minor = 0;
> +	tty_unregister_device(data->tty_drv, minor);
> +
> +	tty_unregister_driver(data->tty_drv);
> +}
> +
> +static int w2sg_suspend(struct device *dev)
> +{
> +	struct w2sg_data *data = dev_get_drvdata(dev);
> +
> +//	spin_lock_irq(&data->lock);
> +	data->suspended = true;
> +//	spin_unlock_irq(&data->lock);
> +
> +	cancel_delayed_work_sync(&data->work);
> +
> +	w2sg_set_lna_power(data);	/* shuts down if needed */
> +
> +	if (data->state == W2SG_PULSE) {
> +		msleep(10);
> +		gpio_set_value_cansleep(data->on_off_gpio, 1);
> +		data->last_toggle = jiffies;
> +		data->is_on = !data->is_on;
> +		data->state = W2SG_NOPULSE;
> +	}
> +
> +	if (data->state == W2SG_NOPULSE) {
> +		msleep(10);
> +		data->state = W2SG_IDLE;
> +	}
> +
> +	if (data->is_on) {
> +		pr_info("GPS off for suspend %d %d %d\n", data->requested,
> +			data->is_on, data->lna_is_off);
> +
> +		gpio_set_value_cansleep(data->on_off_gpio, 0);
> +		msleep(10);
> +		gpio_set_value_cansleep(data->on_off_gpio, 1);
> +		data->is_on = 0;
> +	}
> +
> +	return 0;
> +}
> +
> +static int w2sg_resume(struct device *dev)
> +{
> +	struct w2sg_data *data = dev_get_drvdata(dev);
> +
> +//	spin_lock_irq(&data->lock);
> +	data->suspended = false;
> +//	spin_unlock_irq(&data->lock);
> +
> +	pr_info("GPS resuming %d %d %d\n", data->requested,
> +		data->is_on, data->lna_is_off);
> +
> +	schedule_delayed_work(&data->work, 0);	/* enables LNA if needed */
> +
> +	return 0;
> +}
> +
> +#if defined(CONFIG_OF)
> +static const struct of_device_id w2sg0004_of_match[] = {
> +	{ .compatible = "wi2wi,w2sg0004" },
> +	{ .compatible = "wi2wi,w2sg0084" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, w2sg0004_of_match);
> +#endif
> +
> +SIMPLE_DEV_PM_OPS(w2sg_pm_ops, w2sg_suspend, w2sg_resume);
> +
> +static struct serdev_device_driver w2sg_driver = {
> +	.probe		= w2sg_probe,
> +	.remove		= w2sg_remove,
> +	.driver = {
> +		.name	= "w2sg0004",
> +		.owner	= THIS_MODULE,
> +		.pm	= &w2sg_pm_ops,
> +		.of_match_table = of_match_ptr(w2sg0004_of_match)
> +	},
> +};
> +
> +module_serdev_device_driver(w2sg_driver);
> +
> +MODULE_ALIAS("w2sg0004");
> +
> +MODULE_AUTHOR("NeilBrown <[e-mail]>");
> +MODULE_DESCRIPTION("w2sg0004 GPS power management driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/w2sg0004.h b/include/linux/w2sg0004.h
> new file mode 100644
> index 000000000000..ad0c4a18e01d
> --- /dev/null
> +++ b/include/linux/w2sg0004.h
> @@ -0,0 +1,27 @@
> +/*
> + * UART slave to allow ON/OFF control of w2sg0004 GPS receiver.
> + *
> + * Copyright (C) 2011 Neil Brown <[e-mail]>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * version 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful, but
> + * WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
> + * General Public License for more details.
> + */
> +
> +
> +
> +#ifndef __LINUX_W2SG0004_H
> +#define __LINUX_W2SG0004_H
> +
> +#include <linux/regulator/consumer.h>
> +
> +struct w2sg_pdata {
> +	struct regulator *lna_regulator;	/* enable LNA power */
> +	int	on_off_gpio;	/*  on-off input of the GPS module */
> +};
> +#endif /* __LINUX_W2SG0004_H */
> -- 
> 2.12.2
> 

--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to [e-mail]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Rob Herring (Arm) May 30, 2017, 11:09 p.m. UTC | #2

On Sun, May 21, 2017 at 12:44:03PM +0200, H. Nikolaus Schaller wrote:
> Add driver for Wi2Wi W2SG0004/84 GPS module connected through uart.
> 
> Use serdev API hooks to monitor and forward the UART traffic to /dev/BTn
> and turn on/off the module. It also detects if the module is turned on (sends data)
> but should be off, e.g. if it was already turned on during boot or power-on-reset.
> 
> Additionally, rfkill block/unblock can be used to control an external LNA
> (and power down the module if not needed).
> 
> The driver concept is based on code developed by NeilBrown <[e-mail]>
> but simplified and adapted to use the new serdev API introduced in 4.11.
> 
> Signed-off-by: H. Nikolaus Schaller <[e-mail]>
> ---
>  .../devicetree/bindings/misc/wi2wi,w2sg0004.txt    |  20 +
>  .../devicetree/bindings/vendor-prefixes.txt        |   1 +

Please split binding patches.

>  drivers/misc/Kconfig                               |  16 +
>  drivers/misc/Makefile                              |   1 +
>  drivers/misc/w2sg0004.c                            | 646 +++++++++++++++++++++
>  include/linux/w2sg0004.h                           |  27 +
>  6 files changed, 711 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt
>  create mode 100644 drivers/misc/w2sg0004.c
>  create mode 100644 include/linux/w2sg0004.h
> 
> diff --git a/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt b/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt
> new file mode 100644
> index 000000000000..b7125c7a598c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt
> @@ -0,0 +1,20 @@
> +Wi2Wi GPS module connected through UART
> +
> +Should be a subnode of the SoC UART it is connected to (serdev).
> +
> +Required properties:
> +- compatible:	wi2wi,w2sg0004 or wi2wi,w2sg0084

Reformat to one per line.

> +- on-off-gpio:	the GPIO that controls the module's on-off toggle input

Does enable-gpios or powerdown-gpios work as those are semi-standard 
names. Also, need to state the active state.

> +
> +Optional properties:
> +- lna-suppy:	an (optional) LNA regulator that is enabled together with the GPS receiver

typo

> +
> +Example:
> +
> +&uart2 {
> +	gps: w2sg0004 {

w2sg0004: gps {

The node name should be generic. The label can be whatever you like.

> +		compatible = "wi2wi,w2sg0004";
> +		lna-supply = <&vsim>;   /* LNA regulator */
> +		on-off-gpios = <&gpio5 17 GPIO_ACTIVE_HIGH>;    /* GPIO_145: trigger for turning on/off w2sg0004 */
> +        };
> +};
> diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
> index c03d20140366..c56b3181b266 100644
> --- a/Documentation/devicetree/bindings/vendor-prefixes.txt
> +++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
> @@ -345,6 +345,7 @@ voipac	Voipac Technologies s.r.o.
>  wd	Western Digital Corp.
>  wetek	WeTek Electronics, limited.
>  wexler	Wexler
> +wi2wi	Wi2Wi, Inc.
>  winbond Winbond Electronics corp.
>  winstar	Winstar Display Corp.
>  wlf	Wolfson Microelectronics
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to [e-mail]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

H. Nikolaus Schaller June 6, 2017, 6:50 p.m. UTC | #3

> Am 31.05.2017 um 01:09 schrieb Rob Herring <[e-mail]>:
> 
> On Sun, May 21, 2017 at 12:44:03PM +0200, H. Nikolaus Schaller wrote:
>> Add driver for Wi2Wi W2SG0004/84 GPS module connected through uart.
>> 
>> Use serdev API hooks to monitor and forward the UART traffic to /dev/BTn
>> and turn on/off the module. It also detects if the module is turned on (sends data)
>> but should be off, e.g. if it was already turned on during boot or power-on-reset.
>> 
>> Additionally, rfkill block/unblock can be used to control an external LNA
>> (and power down the module if not needed).
>> 
>> The driver concept is based on code developed by NeilBrown <[e-mail]>
>> but simplified and adapted to use the new serdev API introduced in 4.11.
>> 
>> Signed-off-by: H. Nikolaus Schaller <[e-mail]>
>> ---
>> .../devicetree/bindings/misc/wi2wi,w2sg0004.txt    |  20 +
>> .../devicetree/bindings/vendor-prefixes.txt        |   1 +
> 
> Please split binding patches.

Yes, will do.

We thought that it gives better understanding if kept together with the code in a single patch for this RFC.

> 
>> drivers/misc/Kconfig                               |  16 +
>> drivers/misc/Makefile                              |   1 +
>> drivers/misc/w2sg0004.c                            | 646 +++++++++++++++++++++
>> include/linux/w2sg0004.h                           |  27 +
>> 6 files changed, 711 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt
>> create mode 100644 drivers/misc/w2sg0004.c
>> create mode 100644 include/linux/w2sg0004.h
>> 
>> diff --git a/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt b/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt
>> new file mode 100644
>> index 000000000000..b7125c7a598c
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt
>> @@ -0,0 +1,20 @@
>> +Wi2Wi GPS module connected through UART
>> +
>> +Should be a subnode of the SoC UART it is connected to (serdev).
>> +
>> +Required properties:
>> +- compatible:	wi2wi,w2sg0004 or wi2wi,w2sg0084
> 
> Reformat to one per line.

Ok.

> 
>> +- on-off-gpio:	the GPIO that controls the module's on-off toggle input
> 
> Does enable-gpios or powerdown-gpios work as those are semi-standard 
> names. Also, need to state the active state.

Ok.

> 
>> +
>> +Optional properties:
>> +- lna-suppy:	an (optional) LNA regulator that is enabled together with the GPS receiver
> 
> typo

tnx :)

> 
>> +
>> +Example:
>> +
>> +&uart2 {
>> +	gps: w2sg0004 {
> 
> w2sg0004: gps {
> 
> The node name should be generic. The label can be whatever you like.

Ok. That comes from thoughtless copying very old stuff (I think we started with trying to get this chip DT based around 3.14 kernels...)

> 
>> +		compatible = "wi2wi,w2sg0004";
>> +		lna-supply = <&vsim>;   /* LNA regulator */
>> +		on-off-gpios = <&gpio5 17 GPIO_ACTIVE_HIGH>;    /* GPIO_145: trigger for turning on/off w2sg0004 */
>> +        };
>> +};
>> diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
>> index c03d20140366..c56b3181b266 100644
>> --- a/Documentation/devicetree/bindings/vendor-prefixes.txt
>> +++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
>> @@ -345,6 +345,7 @@ voipac	Voipac Technologies s.r.o.
>> wd	Western Digital Corp.
>> wetek	WeTek Electronics, limited.
>> wexler	Wexler
>> +wi2wi	Wi2Wi, Inc.
>> winbond Winbond Electronics corp.
>> winstar	Winstar Display Corp.
>> wlf	Wolfson Microelectronics

--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to [e-mail]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Ladislav Michl June 7, 2017, 7:34 a.m. UTC | #4

Dear Nikolaus,

On Sun, May 21, 2017 at 12:44:03PM +0200, H. Nikolaus Schaller wrote:
> Add driver for Wi2Wi W2SG0004/84 GPS module connected through uart.
> 
> Use serdev API hooks to monitor and forward the UART traffic to /dev/BTn
> and turn on/off the module. It also detects if the module is turned on (sends data)
> but should be off, e.g. if it was already turned on during boot or power-on-reset.
> 
> Additionally, rfkill block/unblock can be used to control an external LNA
> (and power down the module if not needed).
> 
> The driver concept is based on code developed by NeilBrown <[e-mail]>
> but simplified and adapted to use the new serdev API introduced in 4.11.
[snip]
> diff --git a/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt b/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt
> new file mode 100644
> index 000000000000..b7125c7a598c
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt
> @@ -0,0 +1,20 @@
> +Wi2Wi GPS module connected through UART
> +
> +Should be a subnode of the SoC UART it is connected to (serdev).
> +
> +Required properties:
> +- compatible:	wi2wi,w2sg0004 or wi2wi,w2sg0084
> +- on-off-gpio:	the GPIO that controls the module's on-off toggle input
> +
> +Optional properties:
> +- lna-suppy:	an (optional) LNA regulator that is enabled together with the GPS receiver
> +
> +Example:
> +
> +&uart2 {
> +	gps: w2sg0004 {
> +		compatible = "wi2wi,w2sg0004";
> +		lna-supply = <&vsim>;   /* LNA regulator */
> +		on-off-gpios = <&gpio5 17 GPIO_ACTIVE_HIGH>;    /* GPIO_145: trigger for turning on/off w2sg0004 */
> +        };
> +};

Here it seems is nothing specific to GPS receiver in this driver and
basically UART connected GSM modules could benefit from such functionality
too - as they need power supply, had reset and ignition pin and often
status pin. See for example:
http://simcom.ee/documents/SIM5300E/SIM5300E_Hardware_Design_V1.08.pdf
page 14 or
http://www.robotshop.com/media/files/pdf/datasheet-gsm-tc35.pdf
page 19 for block diagrams.
So I wonder if you would accept making this driver a bit more generic
to cover also GSM modems use case.

Best regards,
	ladis
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to [e-mail]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

H. Nikolaus Schaller June 7, 2017, 10:08 a.m. UTC | #5

Hi Ladislav,

> Am 07.06.2017 um 09:34 schrieb Ladislav Michl <[e-mail]>:
> 
> Dear Nikolaus,
> 
> On Sun, May 21, 2017 at 12:44:03PM +0200, H. Nikolaus Schaller wrote:
>> Add driver for Wi2Wi W2SG0004/84 GPS module connected through uart.
>> 
>> Use serdev API hooks to monitor and forward the UART traffic to /dev/BTn
>> and turn on/off the module. It also detects if the module is turned on (sends data)
>> but should be off, e.g. if it was already turned on during boot or power-on-reset.
>> 
>> Additionally, rfkill block/unblock can be used to control an external LNA
>> (and power down the module if not needed).
>> 
>> The driver concept is based on code developed by NeilBrown <[e-mail]>
>> but simplified and adapted to use the new serdev API introduced in 4.11.
> [snip]
>> diff --git a/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt b/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt
>> new file mode 100644
>> index 000000000000..b7125c7a598c
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt
>> @@ -0,0 +1,20 @@
>> +Wi2Wi GPS module connected through UART
>> +
>> +Should be a subnode of the SoC UART it is connected to (serdev).
>> +
>> +Required properties:
>> +- compatible:	wi2wi,w2sg0004 or wi2wi,w2sg0084
>> +- on-off-gpio:	the GPIO that controls the module's on-off toggle input
>> +
>> +Optional properties:
>> +- lna-suppy:	an (optional) LNA regulator that is enabled together with the GPS receiver
>> +
>> +Example:
>> +
>> +&uart2 {
>> +	gps: w2sg0004 {
>> +		compatible = "wi2wi,w2sg0004";
>> +		lna-supply = <&vsim>;   /* LNA regulator */
>> +		on-off-gpios = <&gpio5 17 GPIO_ACTIVE_HIGH>;    /* GPIO_145: trigger for turning on/off w2sg0004 */
>> +        };
>> +};
> 
> Here it seems is nothing specific to GPS receiver in this driver

Well, most serdev subnodes will look similar to this but still will
need different drivers (timing, pulses, other logic, special functions,
firmware download etc.).

> and
> basically UART connected GSM modules could benefit from such functionality
> too - as they need power supply, had reset and ignition pin and often
> status pin. See for example:
> http://simcom.ee/documents/SIM5300E/SIM5300E_Hardware_Design_V1.08.pdf
> page 14 or
> http://www.robotshop.com/media/files/pdf/datasheet-gsm-tc35.pdf
> page 19 for block diagrams.
> So I wonder if you would accept making this driver a bit more generic
> to cover also GSM modems use case.

We also have such a 2G/3G/4G module in the GTA04 and Pyra devices but there
we have significantly different power control needs because they are connected
through USB and not as UART / serdev.

But you could simply try to use and extend our proposed w2cbw003 bluetooth
driver [RFC 3/3] for that purpose.

It already has most of what you need: provides a user-space /dev/tty for the
serdev and controls some power-control gpio or regulator.

This w2sg0004 gps chip is very specific for this chip since it has no simple
power-enable to be controlled. This also differs too much from GSM modules
with ignition. Especially it has no status feedback.

Another aspect is that there are plans to have some gps infrastructure in the
kernel. Then, this driver wouldn't be the right solution for gsm.

Therefore it is and should remain a special purpose driver for this type of
gps chips.

The common denominator of all these things is the serdev and gpio infrastructure.

Feel free to take both drivers as blueprints to propose some new driver
for your chips.

BR,
Nikolaus

--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to [e-mail]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch

diff --git a/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt b/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt
new file mode 100644
index 000000000000..b7125c7a598c
--- /dev/null
+++ b/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt
@@ -0,0 +1,20 @@ 
+Wi2Wi GPS module connected through UART
+
+Should be a subnode of the SoC UART it is connected to (serdev).
+
+Required properties:
+- compatible:	wi2wi,w2sg0004 or wi2wi,w2sg0084
+- on-off-gpio:	the GPIO that controls the module's on-off toggle input
+
+Optional properties:
+- lna-suppy:	an (optional) LNA regulator that is enabled together with the GPS receiver
+
+Example:
+
+&uart2 {
+	gps: w2sg0004 {
+		compatible = "wi2wi,w2sg0004";
+		lna-supply = <&vsim>;   /* LNA regulator */
+		on-off-gpios = <&gpio5 17 GPIO_ACTIVE_HIGH>;    /* GPIO_145: trigger for turning on/off w2sg0004 */
+        };
+};
diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
index c03d20140366..c56b3181b266 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.txt
+++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
@@ -345,6 +345,7 @@  voipac	Voipac Technologies s.r.o.
 wd	Western Digital Corp.
 wetek	WeTek Electronics, limited.
 wexler	Wexler
+wi2wi	Wi2Wi, Inc.
 winbond Winbond Electronics corp.
 winstar	Winstar Display Corp.
 wlf	Wolfson Microelectronics
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 60f876b03586..7f97ef8fb6cd 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -509,4 +509,20 @@  source "drivers/misc/mic/Kconfig"
 source "drivers/misc/genwqe/Kconfig"
 source "drivers/misc/echo/Kconfig"
 source "drivers/misc/cxl/Kconfig"
+
+config W2SG0004
+	tristate "W2SG00x4 on/off control"
+	depends on GPIOLIB && SERIAL_DEV_BUS
+	help
+          Enable on/off control of W2SG00x4 GPS moduled connected
+	  to some SoC UART to allow powering up/down if the /dev/ttyGPSn
+	  is opened/closed.
+	  It also provides a rfkill gps name to control the LNA power.
+
+config W2SG0004_DEBUG
+	bool "W2SG0004 on/off debugging"
+	depends on W2SG0004
+	help
+	  Enable driver debugging mode of W2SG0004 GPS.
+
 endmenu
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 81ef3e67acc9..0e88e06e5ee0 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -50,6 +50,7 @@  obj-$(CONFIG_SRAM_EXEC)		+= sram-exec.o
 obj-y				+= mic/
 obj-$(CONFIG_GENWQE)		+= genwqe/
 obj-$(CONFIG_ECHO)		+= echo/
+obj-$(CONFIG_W2SG0004)		+= w2sg0004.o
 obj-$(CONFIG_VEXPRESS_SYSCFG)	+= vexpress-syscfg.o
 obj-$(CONFIG_CXL_BASE)		+= cxl/
 obj-$(CONFIG_ASPEED_LPC_CTRL)	+= aspeed-lpc-ctrl.o
diff --git a/drivers/misc/w2sg0004.c b/drivers/misc/w2sg0004.c
new file mode 100644
index 000000000000..1b335317c8ac
--- /dev/null
+++ b/drivers/misc/w2sg0004.c
@@ -0,0 +1,646 @@ 
+/*
+ * w2sg0004.c
+ * Driver for power controlling the w2sg0004/w2sg0084 GPS receiver.
+ *
+ * This receiver has an ON/OFF pin which must be toggled to
+ * turn the device 'on' of 'off'.  A high->low->high toggle
+ * will switch the device on if it is off, and off if it is on.
+ *
+ * To enable receiving on/off requests we register with the
+ * UART power management notifications.
+ *
+ * It is not possible to directly detect the state of the device.
+ * However when it is on it will send characters on a UART line
+ * regularly.
+ *
+ * To detect that the power state is out of sync (e.g. if GPS
+ * was enabled before a reboot), we register for UART data received
+ * notifications.
+ *
+ * In addition we register as a rfkill client so that we can
+ * control the LNA power.
+ *
+ */
+
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_gpio.h>
+#include <linux/platform_device.h>
+#include <linux/rfkill.h>
+#include <linux/serdev.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/w2sg0004.h>
+#include <linux/workqueue.h>
+
+#ifdef CONFIG_W2SG0004_DEBUG	// not for upstreaming
+#undef pr_debug
+#define pr_debug printk
+#endif
+
+/*
+ * There seems to be restrictions on how quickly we can toggle the
+ * on/off line.  data sheets says "two rtc ticks", whatever that means.
+ * If we do it too soon it doesn't work.
+ * So we have a state machine which uses the common work queue to ensure
+ * clean transitions.
+ * When a change is requested we record that request and only act on it
+ * once the previous change has completed.
+ * A change involves a 10ms low pulse, and a 990ms raised level, so only
+ * one change per second.
+ */
+
+enum w2sg_state {
+	W2SG_IDLE,	/* is not changing state */
+	W2SG_PULSE,	/* activate on/off impulse */
+	W2SG_NOPULSE	/* deactivate on/off impulse */
+};
+
+struct w2sg_data {
+	struct		rfkill *rf_kill;
+	struct		regulator *lna_regulator;
+	int		lna_blocked;	/* rfkill block gps active */
+	int		lna_is_off;	/* LNA is currently off */
+	int		is_on;		/* current state (0/1) */
+	unsigned long	last_toggle;
+	unsigned long	backoff;	/* time to wait since last_toggle */
+	int		on_off_gpio;	/* the on-off gpio number */
+	struct		serdev_device *uart;	/* the uart connected to the chip */
+	struct		tty_driver *tty_drv;	/* this is the user space tty */
+	struct		device *dev;	/* returned by tty_port_register_device() */
+	struct		tty_port port;
+	int		open_count;	/* how often we were opened */
+	enum		w2sg_state state;
+	int		requested;	/* requested state (0/1) */
+	int		suspended;
+	spinlock_t	lock;
+	struct delayed_work work;
+	int		discard_count;
+};
+
+static struct w2sg_data *w2sg_by_minor[1];
+
+static int w2sg_set_lna_power(struct w2sg_data *data)
+{
+	int ret = 0;
+	int off = data->suspended || !data->requested || data->lna_blocked;
+
+	pr_debug("%s: %s\n", __func__, off ? "off" : "on");
+
+	if (off != data->lna_is_off) {
+		data->lna_is_off = off;
+		if (!IS_ERR_OR_NULL(data->lna_regulator)) {
+			if (off)
+				regulator_disable(data->lna_regulator);
+			else
+				ret = regulator_enable(data->lna_regulator);
+		}
+	}
+
+	return ret;
+}
+
+static void w2sg_set_power(void *pdata, int val)
+{
+	struct w2sg_data *data = (struct w2sg_data *) pdata;
+
+	pr_debug("%s to state=%d (requested=%d)\n", __func__, val, data->requested);
+
+	if (val && !data->requested) {
+		data->requested = true;
+	} else if (!val && data->requested) {
+		data->backoff = HZ;
+		data->requested = false;
+	} else
+		return;
+
+	pr_debug("w2sg00x4 scheduled for %d\n", data->requested);
+
+	if (!data->suspended)
+		schedule_delayed_work(&data->work, 0);
+}
+
+/* called each time data is received by the UART (i.e. sent by the w2sg0004) */
+
+static int w2sg_uart_receive_buf(struct serdev_device *serdev, const unsigned char *rxdata,
+				size_t count)
+{
+	struct w2sg_data *data = (struct w2sg_data *) serdev_device_get_drvdata(serdev);
+//	unsigned long flags;
+
+//	pr_debug("w2sg: %d characters\n", count);
+
+	if (!data->requested && !data->is_on) {
+		/* we have received characters while the w2sg should have been be turned off */
+		data->discard_count += count;
+		if ((data->state == W2SG_IDLE) &&
+		    time_after(jiffies,
+		    data->last_toggle + data->backoff)) {
+			/* Should be off by now, time to toggle again */
+			pr_debug("w2sg00x4 has sent %d characters data although it should be off!\n", data->discard_count);
+			data->discard_count = 0;
+
+			data->is_on = true;
+			data->backoff *= 2;
+//			spin_lock_irqsave(&data->lock, flags);
+			if (!data->suspended)
+				schedule_delayed_work(&data->work, 0);
+//			spin_unlock_irqrestore(&data->lock, flags);
+		}
+	} else if (data->open_count > 0) {
+		int n;
+
+//		pr_debug("w2sg00x4: push %d chars to tty port\n", count);
+		n = tty_insert_flip_string(&data->port, rxdata, count);	/* pass to user-space */
+		if (n != count)
+			pr_debug("w2sg00x4: did loose %d characters\n", count - n);
+		tty_flip_buffer_push(&data->port);
+		return n;
+	}
+
+	/* assume we have processed everything */
+	return count;
+}
+
+/* try to toggle the power state by sending a pulse to the on-off GPIO */
+
+static void toggle_work(struct work_struct *work)
+{
+	struct w2sg_data *data = container_of(work, struct w2sg_data,
+					      work.work);
+
+	switch (data->state) {
+	case W2SG_IDLE:
+//		spin_lock_irq(&data->lock);
+		if (data->requested == data->is_on) {
+			spin_unlock_irq(&data->lock);
+			return;
+		}
+//		spin_unlock_irq(&data->lock);
+		w2sg_set_lna_power(data);	/* update LNA power state */
+		gpio_set_value_cansleep(data->on_off_gpio, 0);
+		data->state = W2SG_PULSE;
+
+		pr_debug("w2sg: power gpio ON\n");
+
+		schedule_delayed_work(&data->work,
+				      msecs_to_jiffies(10));
+		break;
+
+	case W2SG_PULSE:
+		gpio_set_value_cansleep(data->on_off_gpio, 1);
+		data->last_toggle = jiffies;
+		data->state = W2SG_NOPULSE;
+		data->is_on = !data->is_on;
+
+		pr_debug("w2sg: power gpio OFF\n");
+
+		schedule_delayed_work(&data->work,
+				      msecs_to_jiffies(10));
+		break;
+
+	case W2SG_NOPULSE:
+		data->state = W2SG_IDLE;
+		pr_debug("w2sg: idle\n");
+
+		break;
+
+	}
+}
+
+static int w2sg_rfkill_set_block(void *pdata, bool blocked)
+{
+	struct w2sg_data *data = pdata;
+
+	pr_debug("%s: blocked: %d\n", __func__, blocked);
+
+	data->lna_blocked = blocked;
+
+	return w2sg_set_lna_power(data);
+}
+
+static struct rfkill_ops w2sg0004_rfkill_ops = {
+	.set_block = w2sg_rfkill_set_block,
+};
+
+static struct serdev_device_ops serdev_ops = {
+	.receive_buf = w2sg_uart_receive_buf,
+#if 0
+	.write_wakeup = w2sg_uart_wakeup,
+#endif
+};
+
+/*
+ * we are a man-in the middle between the user-space visible tty port
+ * and the serdev tty where the chip is connected.
+ * This allows us to recognise when the device should be powered on
+ * or off and handle the "false" state that data arrives while no
+ * users-space tty client exists.
+ */
+
+static struct w2sg_data *w2sg_get_by_minor(unsigned int minor)
+{
+	return w2sg_by_minor[minor];
+}
+
+static int w2sg_tty_install(struct tty_driver *driver, struct tty_struct *tty)
+{
+	struct w2sg_data *data;
+	int retval;
+
+	pr_debug("%s() tty = %p\n", __func__, tty);
+
+	data = w2sg_get_by_minor(tty->index);
+	pr_debug("%s() data = %p\n", __func__, data);
+
+	if (!data)
+		return -ENODEV;
+
+	retval = tty_standard_install(driver, tty);
+	if (retval)
+		goto error_init_termios;
+
+	tty->driver_data = data;
+
+	return 0;
+
+error_init_termios:
+	tty_port_put(&data->port);
+	return retval;
+}
+
+static int w2sg_tty_open(struct tty_struct *tty, struct file *file)
+{
+	struct w2sg_data *data = tty->driver_data;
+
+	pr_debug("%s() data = %p open_count = ++%d\n", __func__, data, data->open_count);
+//	val = (val & TIOCM_DTR) != 0;	/* DTR controls power on/off */
+
+	w2sg_set_power(data, ++data->open_count > 0);
+
+// we could/should return -Esomething if already open...
+
+	return tty_port_open(&data->port, tty, file);
+}
+
+static void w2sg_tty_close(struct tty_struct *tty, struct file *file)
+{
+	struct w2sg_data *data = tty->driver_data;
+
+	pr_debug("%s()\n", __func__);
+//	val = (val & TIOCM_DTR) != 0;	/* DTR controls power on/off */
+	w2sg_set_power(data, --data->open_count > 0);
+
+	tty_port_close(&data->port, tty, file);
+}
+
+static int w2sg_tty_write(struct tty_struct *tty,
+		const unsigned char *buffer, int count)
+{
+	struct w2sg_data *data = tty->driver_data;
+
+	/* simply pass down to UART */
+	return serdev_device_write_buf(data->uart, buffer, count);
+}
+
+#if 0
+static void w2sg_tty_tiocmget(...)
+{
+	int val;
+
+	pr_debug("%s(...,%x)\n", __func__, val);
+	val = (val & TIOCM_DTR) != 0;	/* DTR controls power on/off */
+	w2sg_set_power((struct w2sg_data *) pdata, val);
+}
+#endif
+
+
+static const struct tty_operations w2sg_serial_ops = {
+	.install = w2sg_tty_install,
+	.open = w2sg_tty_open,
+	.close = w2sg_tty_close,
+	.write = w2sg_tty_write,
+#if 0
+	.write_room = w2sg_tty_write_room,
+	.cleanup = w2sg_tty_cleanup,
+	.ioctl = w2sg_tty_ioctl,
+	.set_termios = w2sg_tty_set_termios,
+	.chars_in_buffer = w2sg_tty_chars_in_buffer,
+	.tiocmget = w2sg_tty_tiocmget,
+	.tiocmset = w2sg_tty_tiocmset,
+	.get_icount = w2sg_tty_get_count,
+	.unthrottle = w2sg_tty_unthrottle
+#endif
+};
+
+static const struct tty_port_operations w2sg_port_ops = {
+};
+
+static int w2sg_probe(struct serdev_device *serdev)
+{
+	struct w2sg_pdata *pdata = NULL;
+	struct w2sg_data *data;
+	struct rfkill *rf_kill;
+	int err;
+	int minor;
+
+	pr_debug("%s()\n", __func__);
+
+	minor = 0;
+	if (w2sg_by_minor[minor]) {
+		pr_err("w2sg minor is already in use!\n");
+		return -ENODEV;
+	}
+
+// can be simplified if we require OF
+
+	if (serdev->dev.of_node) {
+		struct device *dev = &serdev->dev;
+		enum of_gpio_flags flags;
+
+		pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
+		if (!pdata)
+			return -ENOMEM;
+
+		pdata->on_off_gpio = of_get_named_gpio_flags(dev->of_node,
+							     "on-off-gpios", 0,
+							     &flags);
+
+		if (pdata->on_off_gpio == -EPROBE_DEFER)
+			return -EPROBE_DEFER;	/* defer until we have all gpios */
+
+		pdata->lna_regulator = devm_regulator_get_optional(dev, "lna");
+// shouldn't we defer probing as well???
+
+		pr_debug("%s() lna_regulator = %p\n", __func__, pdata->lna_regulator);
+
+		serdev->dev.platform_data = pdata;
+	}
+
+	data = devm_kzalloc(&serdev->dev, sizeof(*data), GFP_KERNEL);
+	if (data == NULL)
+		return -ENOMEM;
+
+	w2sg_by_minor[minor] = data;
+
+#if 1
+	pr_debug("w2sg serdev_device_set_drvdata\n");
+#endif
+	serdev_device_set_drvdata(serdev, data);
+
+	data->lna_regulator = pdata->lna_regulator;
+	data->lna_blocked = true;
+	data->lna_is_off = true;
+
+	data->on_off_gpio = pdata->on_off_gpio;
+
+	data->is_on = false;
+	data->requested = false;
+	data->state = W2SG_IDLE;
+	data->last_toggle = jiffies;
+	data->backoff = HZ;
+
+	data->uart = serdev;
+
+	INIT_DELAYED_WORK(&data->work, toggle_work);
+//	spin_lock_init(&data->lock);
+
+#if 1
+	pr_debug("w2sg devm_gpio_request\n");
+#endif
+	err = devm_gpio_request(&serdev->dev, data->on_off_gpio, "w2sg0004-on-off");
+	if (err < 0)
+		goto out;
+
+	gpio_direction_output(data->on_off_gpio, false);
+
+	serdev_device_set_client_ops(data->uart, &serdev_ops);
+	serdev_device_open(data->uart);
+
+	serdev_device_set_baudrate(data->uart, 9600);
+	serdev_device_set_flow_control(data->uart, false);
+
+#if 1
+	pr_debug("w2sg rfkill_alloc\n");
+#endif
+	rf_kill = rfkill_alloc("GPS", &serdev->dev, RFKILL_TYPE_GPS,
+				&w2sg0004_rfkill_ops, data);
+	if (rf_kill == NULL) {
+		err = -ENOMEM;
+		goto err_rfkill;
+	}
+
+#if 1
+	pr_debug("w2sg register rfkill\n");
+#endif
+	err = rfkill_register(rf_kill);
+	if (err) {
+		dev_err(&serdev->dev, "Cannot register rfkill device\n");
+		goto err_rfkill;
+	}
+
+	data->rf_kill = rf_kill;
+
+#if 1
+	pr_debug("w2sg alloc_tty_driver\n");
+#endif
+	/* allocate the tty driver */
+	data->tty_drv = alloc_tty_driver(1);
+	if (!data->tty_drv)
+		return -ENOMEM;
+
+	/* initialize the tty driver */
+	data->tty_drv->owner = THIS_MODULE;
+	data->tty_drv->driver_name = "w2sg0004";
+	data->tty_drv->name = "ttyGPS";
+	data->tty_drv->major = 0;
+	data->tty_drv->minor_start = 0;
+	data->tty_drv->type = TTY_DRIVER_TYPE_SERIAL;
+	data->tty_drv->subtype = SERIAL_TYPE_NORMAL;
+	data->tty_drv->flags = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;
+	data->tty_drv->init_termios = tty_std_termios;
+	data->tty_drv->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;
+	/*
+	 * tty_termios_encode_baud_rate(&data->tty_drv->init_termios, 115200, 115200);
+	 * w2sg_tty_termios(&data->tty_drv->init_termios);
+	 */
+	tty_set_operations(data->tty_drv, &w2sg_serial_ops);
+
+#if 1
+	pr_debug("w2sg tty_register_driver\n");
+#endif
+	/* register the tty driver */
+	err = tty_register_driver(data->tty_drv);
+	if (err) {
+		pr_err("%s - tty_register_driver failed(%d)\n",
+			__func__, err);
+		put_tty_driver(data->tty_drv);
+		goto err_rfkill;
+	}
+
+#if 1
+	pr_debug("w2sg call tty_port_init\n");
+#endif
+	tty_port_init(&data->port);
+	data->port.ops = &w2sg_port_ops;
+
+#if 1
+	pr_debug("w2sg call tty_port_register_device\n");
+#endif
+/*
+ * FIXME: this appears to reenter this probe() function a second time
+ * which only fails because the gpio is already assigned
+ */
+
+	data->dev = tty_port_register_device(&data->port,
+			data->tty_drv, minor, &serdev->dev);
+
+#if 1
+	pr_debug("w2sg tty_port_register_device -> %p\n", data->dev);
+	pr_debug("w2sg port.tty = %p\n", data->port.tty);
+#endif
+//	data->port.tty->driver_data = data;	/* make us known in tty_struct */
+
+	pr_debug("w2sg probed\n");
+
+#ifdef CONFIG_W2SG0004_DEBUG
+	pr_debug("w2sg DEBUGGING MODE enabled\n");
+	/* turn on for debugging rx notifications */
+	pr_debug("w2sg power gpio ON\n");
+	gpio_set_value_cansleep(data->on_off_gpio, 1);
+	mdelay(100);
+	pr_debug("w2sg power gpio OFF\n");
+	gpio_set_value_cansleep(data->on_off_gpio, 0);
+	mdelay(300);
+#endif
+
+	/* keep off until user space requests the device */
+	w2sg_set_power(data, false);
+
+#if 0	// more debugging - not for upstreaming
+	w2sg_set_power(data, true);
+#endif
+
+	return 0;
+
+err_rfkill:
+	rfkill_destroy(rf_kill);
+	serdev_device_close(data->uart);
+out:
+#if 0
+	if (err == -EBUSY)
+		err = -EPROBE_DEFER;
+#endif
+#if 1
+	pr_debug("w2sg error %d\n", err);
+#endif
+	return err;
+}
+
+static void w2sg_remove(struct serdev_device *serdev)
+{
+	struct w2sg_data *data = serdev_device_get_drvdata(serdev);
+	int minor;
+
+	cancel_delayed_work_sync(&data->work);
+
+	/* what is the right sequence to avoid problems? */
+	serdev_device_close(data->uart);
+
+	// get minor from searching for data == w2sg_by_minor[minor]
+	minor = 0;
+	tty_unregister_device(data->tty_drv, minor);
+
+	tty_unregister_driver(data->tty_drv);
+}
+
+static int w2sg_suspend(struct device *dev)
+{
+	struct w2sg_data *data = dev_get_drvdata(dev);
+
+//	spin_lock_irq(&data->lock);
+	data->suspended = true;
+//	spin_unlock_irq(&data->lock);
+
+	cancel_delayed_work_sync(&data->work);
+
+	w2sg_set_lna_power(data);	/* shuts down if needed */
+
+	if (data->state == W2SG_PULSE) {
+		msleep(10);
+		gpio_set_value_cansleep(data->on_off_gpio, 1);
+		data->last_toggle = jiffies;
+		data->is_on = !data->is_on;
+		data->state = W2SG_NOPULSE;
+	}
+
+	if (data->state == W2SG_NOPULSE) {
+		msleep(10);
+		data->state = W2SG_IDLE;
+	}
+
+	if (data->is_on) {
+		pr_info("GPS off for suspend %d %d %d\n", data->requested,
+			data->is_on, data->lna_is_off);
+
+		gpio_set_value_cansleep(data->on_off_gpio, 0);
+		msleep(10);
+		gpio_set_value_cansleep(data->on_off_gpio, 1);
+		data->is_on = 0;
+	}
+
+	return 0;
+}
+
+static int w2sg_resume(struct device *dev)
+{
+	struct w2sg_data *data = dev_get_drvdata(dev);
+
+//	spin_lock_irq(&data->lock);
+	data->suspended = false;
+//	spin_unlock_irq(&data->lock);
+
+	pr_info("GPS resuming %d %d %d\n", data->requested,
+		data->is_on, data->lna_is_off);
+
+	schedule_delayed_work(&data->work, 0);	/* enables LNA if needed */
+
+	return 0;
+}
+
+#if defined(CONFIG_OF)
+static const struct of_device_id w2sg0004_of_match[] = {
+	{ .compatible = "wi2wi,w2sg0004" },
+	{ .compatible = "wi2wi,w2sg0084" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, w2sg0004_of_match);
+#endif
+
+SIMPLE_DEV_PM_OPS(w2sg_pm_ops, w2sg_suspend, w2sg_resume);
+
+static struct serdev_device_driver w2sg_driver = {
+	.probe		= w2sg_probe,
+	.remove		= w2sg_remove,
+	.driver = {
+		.name	= "w2sg0004",
+		.owner	= THIS_MODULE,
+		.pm	= &w2sg_pm_ops,
+		.of_match_table = of_match_ptr(w2sg0004_of_match)
+	},
+};
+
+module_serdev_device_driver(w2sg_driver);
+
+MODULE_ALIAS("w2sg0004");
+
+MODULE_AUTHOR("NeilBrown <[e-mail]>");
+MODULE_DESCRIPTION("w2sg0004 GPS power management driver");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/w2sg0004.h b/include/linux/w2sg0004.h
new file mode 100644
index 000000000000..ad0c4a18e01d
--- /dev/null
+++ b/include/linux/w2sg0004.h
@@ -0,0 +1,27 @@ 
+/*
+ * UART slave to allow ON/OFF control of w2sg0004 GPS receiver.
+ *
+ * Copyright (C) 2011 Neil Brown <[e-mail]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+
+
+#ifndef __LINUX_W2SG0004_H
+#define __LINUX_W2SG0004_H
+
+#include <linux/regulator/consumer.h>
+
+struct w2sg_pdata {
+	struct regulator *lna_regulator;	/* enable LNA power */
+	int	on_off_gpio;	/*  on-off input of the GPS module */
+};
+#endif /* __LINUX_W2SG0004_H */