Hi!
> --- a/drivers/misc/Kconfig
> +++ b/drivers/misc/Kconfig
> @@ -515,6 +515,16 @@ config VEXPRESS_SYSCFG
> bus. System Configuration interface is one of the possible means
> of generating transactions on this bus.
>
> +config W2SG0004
> + tristate "W2SG0004 on/off control"
~~ insert GPS here.
And make it bool if it can't be a module.
> + depends on GPIOLIB
> + help
> + Enable on/off control of W2SG0004 GPS using a virtual GPIO.
> + The virtual GPIO can be connected to a DTR line of a serial
> + interface to allow powering up if the /dev/tty$n is opened.
> + It also provides a rfkill gps node to control the LNA power.
> + NOTE: can't currently be compiled as module, so please choose Y.
> +
> +++ b/drivers/misc/w2sg0004.c
> @@ -0,0 +1,512 @@
> +/*
> + * w2sg0004.c
> + * Virtual GPIO of controlling the w2sg0004 GPS receiver.
> + *
> + * Copyright (C) 2011 Neil Brown <neil@xxxxxxxxxx>
> + *
> + * This receiver has an ON/OFF pin which must be toggled to
> + * turn the device 'on' or 'off'. A high->low->high toggle
> + * will switch the device on if it is off, and off if it is on.
> + * 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.
> + * On the OMAP3, the UART line can also be programmed as a GPIO
> + * on which we can receive interrupts.
> + * So when we want the device to be 'off' we can reprogram
> + * the line, toggle the ON/OFF pin and hope that it is off.
> + * However if an interrupt arrives we know that it is really on
> + * and can toggle again.
> + *
> + * To enable receiving on/off requests we create a gpio_chip
> + * with a single 'output' GPIO. When it is low, the
> + * GPS is turned off. When it is high, it is turned on.
> + * This can be configured as the DTR GPIO on the UART which
> + * connects the GPS. Then whenever the tty is open, the GPS
> + * will be switched on, and whenever it is closed, the GPS will
> + * be switched off.
> + *
> + * In addition we register as a rfkill client so that we can
> + * control the LNA power.
> + *
> + */
GPL?
> +/*
> + * There seems to restrictions on how quickly we can toggle the
> + * on/off line. data sheets says "two rtc ticks", whatever that means.
"seems to"? data -> Data?
> +enum w2sg_state {
> + W2SG_IDLE, /* is not changing state */
> + W2SG_PULSE, /* activate on/off impulse */
> + W2SG_NOPULSE /* desctivate on/off impulse */
> +};
deactivate.
> +
> +struct gpio_w2sg {
> + 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;
> + int rx_irq;
> +
> + struct pinctrl *p;
> + struct pinctrl_state *default_state; /* should be UART mode */
> + struct pinctrl_state *monitor_state; /* monitor RX as GPIO */
> + enum w2sg_state state;
> + int requested; /* requested state (0/1) */
> + int suspended;
> + int rx_redirected;
> + spinlock_t lock;
> +#ifdef CONFIG_GPIOLIB
> + struct gpio_chip gpio;
> + const char *gpio_name[1];
> +#endif
Depends on gpiolib, why ifdef?
Array of names?
> + rf_kill = rfkill_alloc("GPS", &pdev->dev, RFKILL_TYPE_GPS,
> + &gpio_w2sg0004_rfkill_ops, gw2sg);
Actually, is rfkill interface right one on GPS? GPS is not supposed to
transmit...
> + int gpio_base; /* (not used by DT) - defines the gpio.base */
Is non-device tree path still usefull?
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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