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Date: Tue, 30 Jun 2015 11:23:54 +0300
From: Sergei Zviagintsev <sergei@...v.net>
To: Marek Belisko <marek@...delico.com>
Cc: jslaby@...e.cz, gregkh@...uxfoundation.org, arnd@...db.de,
peter@...leysoftware.com, mark.rutland@....com,
gnomes@...rguk.ukuu.org.uk, sre@...nel.org, neil@...wn.name,
grant.likely@...aro.org, linux-kernel@...r.kernel.org,
linux-serial@...r.kernel.org, robh+dt@...nel.org,
pawel.moll@....com, hns@...delico.com
Subject: Re: [PATCH RFC v2 3/3] misc: Add w2g0004 gps receiver driver
Hi,
I left some comments below.
On Sun, Jun 28, 2015 at 09:46:26PM +0200, Marek Belisko wrote:
> From: "H. Nikolaus Schaller" <hns@...delico.com>
>
> Add driver for Wi2Wi w2g004 GPS module connected through uart. Use uart
> slave + notification hooks to glue with tty.
>
> Signed-off-by: H. Nikolaus Schaller <hns@...delico.com>
> Signed-off-by: Marek Belisko <marek@...delico.com>
> ---
> .../devicetree/bindings/misc/wi2wi,w2sg0004.txt | 18 +
> drivers/misc/Kconfig | 18 +
> drivers/misc/Makefile | 1 +
> drivers/misc/w2sg0004.c | 436 +++++++++++++++++++++
> include/linux/w2sg0004.h | 28 ++
> 5 files changed, 501 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 0000000..ef0d6d5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/misc/wi2wi,w2sg0004.txt
> @@ -0,0 +1,18 @@
> +Wi2Wi GPS module connected through UART
> +
> +Required properties:
> +- compatible: wi2wi,w2sg0004 or wi2wi,w2sg0084
> +- on-off-gpio: the GPIO that controls the module's on-off toggle input
> +- uart: the uart we are connected to (provides DTR for power control)
> +
> +Optional properties:
> +- lna-suppy: an (optional) LNA regulator that is enabled together with the GPS receiver
> +
> +example:
> +
> + gps_receiver: w2sg0004 {
> + compatible = "wi2wi,w2sg0004";
> + lna-supply = <&vsim>; /* LNA regulator */
> + on-off-gpio = <&gpio5 17 0>; /* GPIO_145: trigger for turning on/off w2sg0004 */
> + uart = <&uart1>; /* we are a slave of uart1 */
> + }
> diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
> index 42c3852..952add4 100644
> --- a/drivers/misc/Kconfig
> +++ b/drivers/misc/Kconfig
> @@ -527,4 +527,22 @@ source "drivers/misc/mic/Kconfig"
> source "drivers/misc/genwqe/Kconfig"
> source "drivers/misc/echo/Kconfig"
> source "drivers/misc/cxl/Kconfig"
> +
> +menu "GTA04 misc hardware support"
> +
> +config W2SG0004
> + tristate "W2SG0004 on/off control"
> + depends on GPIOLIB
> + help
> + Enable on/off control of W2SG0004 GPS using a tty slave to
> + to allow powering up if the /dev/tty$n is opened.
> + It also provides a rfkill gps node to control the LNA power.
> +
> +config W2SG0004_DEBUG
> + bool "W2SG0004 on/off debugging"
> + depends on W2SG0004
> + help
> + Enable driver debugging mode of W2SG0004 GPS.
> +
> +endmenu
> endmenu
> diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
> index d056fb7..3bc67c7 100644
> --- a/drivers/misc/Makefile
> +++ b/drivers/misc/Makefile
> @@ -53,5 +53,6 @@ obj-$(CONFIG_SRAM) += sram.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/
> diff --git a/drivers/misc/w2sg0004.c b/drivers/misc/w2sg0004.c
> new file mode 100644
> index 0000000..c5f0f7b
> --- /dev/null
> +++ b/drivers/misc/w2sg0004.c
> @@ -0,0 +1,436 @@
> +/*
> + * 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/module.h>
> +#include <linux/interrupt.h>
> +#include <linux/sched.h>
> +#include <linux/irq.h>
> +#include <linux/slab.h>
> +#include <linux/err.h>
> +#include <linux/delay.h>
> +#include <linux/of.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_gpio.h>
> +#include <linux/platform_device.h>
> +#include <linux/w2sg0004.h>
> +#include <linux/workqueue.h>
> +#include <linux/rfkill.h>
> +#include <linux/serial_core.h>
> +
> +#ifdef CONFIG_W2SG0004_DEBUG
> +#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) */
Wouldn't bool types be better for these three and also for `requested'
and `suspended'?
> + unsigned long last_toggle;
> + unsigned long backoff; /* time to wait since last_toggle */
> + int on_off_gpio; /* the on-off gpio number */
> + struct uart_port *uart; /* the drvdata of the uart or tty */
> + enum w2sg_state state;
> + int requested; /* requested state (0/1) */
> + int suspended;
> + spinlock_t lock;
> + struct delayed_work work;
> +};
> +
> +static int w2sg_data_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_data_set_power(void *pdata, int val)
int val -> bool val?
> +{
> + struct w2sg_data *data = (struct w2sg_data *) pdata;
> + unsigned long flags;
> +
> + pr_debug("%s to %d (%d)\n", __func__, val, data->requested);
> +
> + spin_lock_irqsave(&data->lock, flags);
> +
> + if (val && !data->requested) {
> + data->requested = true;
> + } else if (!val && data->requested) {
> + data->backoff = HZ;
> + data->requested = false;
> + } else
Braces issue with `else' branch.
> + goto unlock;
> +
> + pr_debug("w2sg scheduled for %d\n", data->requested);
> +
> + if (!data->suspended)
> + schedule_delayed_work(&data->work, 0);
> +unlock:
> + spin_unlock_irqrestore(&data->lock, flags);
> +}
> +
> +/* called each time data is received by the host (i.e. sent by the w2sg0004) */
> +
> +static int rx_notification(void *pdata, unsigned int *c)
> +{
> + struct w2sg_data *data = (struct w2sg_data *) pdata;
> + unsigned long flags;
> +
> + if (!data->requested && !data->is_on) {
Isn't it better to invert the if-statement and place return to be less
indented and more readable?
> + pr_debug("%02x!", *c); /* we have received a RX signal while GPS should be off */
> + if ((data->state == W2SG_IDLE) &&
> + time_after(jiffies,
> + data->last_toggle + data->backoff)) {
Whole time_after() call should be on the same line.
> + /* Should be off by now, time to toggle again */
> + pr_debug("w2sg has sent data although it should be off!\n");
> + 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);
> + }
> + }
> + return 0; /* forward to tty */
> +}
> +
> +/* called by uart modem control line changes (DTR) */
> +
> +static int w2sg_mctrl(void *pdata, int val)
> +{
> + pr_debug("%s(...,%x)\n", __func__, val);
> + val = (val & TIOCM_DTR) != 0; /* DTR controls power on/off */
IMO the following would be more readable:
bool power_on = !!(val & TIOCM_DTR);
> + w2sg_data_set_power((struct w2sg_data *) pdata, val);
> + return 0;
> +}
> +
> +/* 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_data_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;
> +
default case?
> + }
> +}
> +
> +static int w2sg_data_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_data_set_lna_power(data);
> +}
> +
> +static struct rfkill_ops w2sg_data0004_rfkill_ops = {
> + .set_block = w2sg_data_rfkill_set_block,
> +};
> +
> +static int w2sg_data_probe(struct platform_device *pdev)
> +{
> + struct w2sg_pdata *pdata = dev_get_platdata(&pdev->dev);
> + struct w2sg_data *data;
> + struct rfkill *rf_kill;
> + int err;
> +
> + pr_debug("%s()\n", __func__);
> +
> + if (pdev->dev.of_node) {
> + struct device *dev = &pdev->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-gpio", 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");
> +
> + pr_debug("%x() lna_regulator = %p\n", __func__, pdata->lna_regulator);
> +
> + pdev->dev.platform_data = pdata;
> + }
> +
> + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> + if (data == NULL)
> + return -ENOMEM;
> +
> + 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;
> +
> +#ifdef CONFIG_OF
> + data->uart = devm_serial_get_uart_by_phandle(&pdev->dev, "uart", 0);
> + if (IS_ERR(data->uart)) {
> + if (PTR_ERR(data->uart) == -EPROBE_DEFER)
> + return -EPROBE_DEFER; /* we can't probe yet */
> + else
`else' is redundand
> + data->uart = NULL; /* no UART */
> + }
> +#endif
> +
> + INIT_DELAYED_WORK(&data->work, toggle_work);
> + spin_lock_init(&data->lock);
> +
> + err = devm_gpio_request(&pdev->dev, data->on_off_gpio, "w2sg0004-on-off");
> + if (err < 0)
> + goto out;
> +
> + gpio_direction_output(data->on_off_gpio, false);
> +
> + if (data->uart) {
> + struct ktermios termios = {
> + .c_iflag = IGNBRK,
> + .c_oflag = 0,
> + .c_cflag = B9600 | CS8,
> + .c_lflag = 0,
> + .c_line = 0,
> + .c_ispeed = 9600,
> + .c_ospeed = 9600
> + };
> + uart_register_slave(data->uart, data);
> + uart_register_mctrl_notification(data->uart, w2sg_mctrl);
> + uart_register_rx_notification(data->uart, rx_notification, &termios);
> + }
> +
> + rf_kill = rfkill_alloc("GPS", &pdev->dev, RFKILL_TYPE_GPS,
> + &w2sg_data0004_rfkill_ops, data);
> + if (rf_kill == NULL) {
> + err = -ENOMEM;
> + goto err_rfkill;
return -ENOMEM;
> + }
> +
> + err = rfkill_register(rf_kill);
> + if (err) {
> + dev_err(&pdev->dev, "Cannot register rfkill device\n");
> + goto err_rfkill;
> + }
> +
> + data->rf_kill = rf_kill;
> +
> + platform_set_drvdata(pdev, data);
> +
> + pr_debug("w2sg0004 probed\n");
> +
> +#ifdef CONFIG_W2SG0004_DEBUG
> + /* 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
> +
> + /* if we won't receive mctrl notifications, turn on.
> + * otherwise keep off until DTR is asserted through mctrl.
> + */
> +
> + w2sg_data_set_power(data, !data->uart);
> +
> + return 0;
> +
> +err_rfkill:
> + rfkill_destroy(rf_kill);
> +out:
`out' label is useless as no cleanup code here.
Keeping in mind that the one of two `goto err_rfkill' is incorrect,
`err_rfkill' label can be removed as there is the only one code path
left which is using it.
> + return err;
> +}
> +
> +static int w2sg_data_remove(struct platform_device *pdev)
> +{
> + struct w2sg_data *data = platform_get_drvdata(pdev);
> +
> + cancel_delayed_work_sync(&data->work);
> +
> + if (data->uart) {
> + uart_register_rx_notification(data->uart, NULL, NULL);
> + uart_register_slave(data->uart, NULL);
> + }
> + return 0;
> +}
> +
> +static int w2sg_data_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_data_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;
0 -> false (to stay similar with other code)
> + }
> +
> + return 0;
> +}
> +
> +static int w2sg_data_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_data_suspend, w2sg_data_resume);
> +
> +static struct platform_driver w2sg_data_driver = {
> + .probe = w2sg_data_probe,
> + .remove = w2sg_data_remove,
> + .driver = {
> + .name = "w2sg0004",
> + .owner = THIS_MODULE,
> + .pm = &w2sg_pm_ops,
> + .of_match_table = of_match_ptr(w2sg0004_of_match)
> + },
> +};
> +
> +module_platform_driver(w2sg_data_driver);
> +
> +MODULE_ALIAS("w2sg0004");
> +
> +MODULE_AUTHOR("NeilBrown <neilb@...e.de>");
> +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 0000000..7aee709
> --- /dev/null
> +++ b/include/linux/w2sg0004.h
> @@ -0,0 +1,28 @@
> +/*
> + * UART slave to allow ON/OFF control of w2sg0004 GPS receiver.
> + *
> + * Copyright (C) 2011 Neil Brown <neil@...wn.name>
> + *
> + * 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; /* connected to the on-off input of the GPS module */
> +};
> +#endif /* __LINUX_W2SG0004_H */
> --
> 1.9.1
>
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