[PATCH v8] usb:serial:pl2303: add GPIOs interface on PL2303

[Wang YanQing <udknight@gmail.com>]

PL2303 USB Serial devices may has GPIOs, this patch add
basic PL2303 gpio support.

Known issue:
If gpios are in use(export to userspace through sysfs interface, etc),
then call pl2303_release(unplug usb-serial convertor, modprobe -r, etc),
will cause trouble, so we need to make sure there is no gpio user before
call pl2303_release.

Signed-off-by: Wang YanQing <udknight@gmail.com>
---
 Note: I sniffed office HXD gpio test program to get 
       gpios control protocol with PL2303 RA, so I only
       test it with PL2303 RA and HXA, I don't have HXD,
       but because it is *office* HXD gpio test program,
       so if it doesn't work with HXD, I will feel surprise.

 Changes
 v7-v8:
 1: add support for four dedicated gpios on HXD and RA
 2: fix problem reported by Johan Hovold in v7
 3: fix checkpatch.pl's warning

 v6-v7:
 1: add generic gpio support interfaces for pl2303 USB Serial devices
    in pl2303_type_data and pl2303_serial_private suggested by Andreas Mohr.
 2: drop different label names for different pl2303 instance suggested by Johan Hovold.
 3: fix missing lock corrected by Johan Hovold.
 4: use prefix pl2303hx_gpio instead pl2303_gpio, pl2303_gpio is over generic for current code,
    and now we move gpio_startup|gpio_release into type-specified data structure, so pl2303hx_gpio
    is a better prefix.
 5: make words in Kconfig a little more useful and clarified.
 6: many misc code quality enhancement suggested by Johan Hovold.

 v5-v6:
 1: fix typo error in Kconfig reported by Andreas Mohr 
 2: add const qulification to gpio_dir_mask and gpio_value_mask suggested by Andreas Mohr

 v4-v5:
 1: fix gpio_chip.lable been overwrited by template_chip. 
 2: use idr to manage minor instead of crude monotonous atomic increment. 

 v3-v4:
 1: fix missing static for gpio_dir_mask and gpio_value_mask 
 2: reduce unneeded compile macro defined suggested by gnomes@lxorguk.ukuu.org.uk 
 3: use true instead of 1 corrected by Linus Walleij
 4: ignore return value of gpiochip_remove suggested by Linus Walleij
 5: fix multi gpio_chips registered by pl2303 can't be distinguished in kernel space. 

 v2-v3:
 1: fix errors and warnings reported by Daniele Forsi checked with checkpatch.pl 
 2: fix missing GPIOLIB dependence in Kconfig 
 3: fix pl2303_gpio_get can't work 

 v1-v2:  
 1:drop gpio-pl2303.c and relation stuff 
 2:hang gpio stuff off of pl2303.c  

 drivers/usb/serial/Kconfig  |  11 ++
 drivers/usb/serial/pl2303.c | 250 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 261 insertions(+)

diff --git a/drivers/usb/serial/Kconfig b/drivers/usb/serial/Kconfig
index 3ce5c74..b4e0cf9 100644
--- a/drivers/usb/serial/Kconfig
+++ b/drivers/usb/serial/Kconfig
@@ -516,6 +516,17 @@ config USB_SERIAL_PL2303
 	  To compile this driver as a module, choose M here: the
 	  module will be called pl2303.
 
+config USB_SERIAL_PL2303_GPIO
+	bool "USB Prolific 2303 Single Port GPIOs support"
+	depends on USB_SERIAL_PL2303 && GPIOLIB
+	---help---
+	  Say Y here if you want to use GPIOs on PL2303 USB Serial single port
+	  adapter from Prolific.
+
+	  It supports 2 dedicated GPIOs on PL2303HXA, 4 dedicated GPIOs on
+	  PL2303HXD and PL2303RA currently.
+	  If unsure, say N.
+
 config USB_SERIAL_OTI6858
 	tristate "USB Ours Technology Inc. OTi-6858 USB To RS232 Bridge Controller"
 	help
diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index e9bad92..a3f8411 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -28,6 +28,8 @@
 #include <linux/usb.h>
 #include <linux/usb/serial.h>
 #include <asm/unaligned.h>
+#include <linux/gpio.h>
+#include <linux/mutex.h>
 #include "pl2303.h"
 
 
@@ -132,6 +134,22 @@ MODULE_DEVICE_TABLE(usb, id_table);
 #define UART_OVERRUN_ERROR		0x40
 #define UART_CTS			0x80
 
+#define HXD_GPIO_01_CTRL		0x0001
+#define HXD_GPIO_01_VALUE		0x0081
+#define HXD_GPIO_23_DIR_CTRL		0x0c0c
+#define HXD_GPIO_23_VALUE_CTRL		0x0d0d
+#define HXD_GPIO_23_VALUE		0x8d8d
+
+#define HXD_GPIO0_DIR_MASK		0x10
+#define HXD_GPIO1_DIR_MASK		0x20
+#define HXD_GPIO2_DIR_MASK		0x03
+#define HXD_GPIO3_DIR_MASK		0x0c
+
+#define HXD_GPIO0_VALUE_MASK		0x40
+#define HXD_GPIO1_VALUE_MASK		0x80
+#define HXD_GPIO2_VALUE_MASK		0x01
+#define HXD_GPIO3_VALUE_MASK		0x02
+
 
 enum pl2303_type {
 	TYPE_01,	/* Type 0 and 1 (difference unknown) */
@@ -144,9 +162,12 @@ struct pl2303_type_data {
 	unsigned long quirks;
 };
 
+struct pl2303_gpio;
 struct pl2303_serial_private {
 	const struct pl2303_type_data *type;
 	unsigned long quirks;
+	u8 ngpio;
+	struct pl2303_gpio *gpio;
 };
 
 struct pl2303_private {
@@ -157,6 +178,14 @@ struct pl2303_private {
 	u8 line_settings[7];
 };
 
+#ifdef CONFIG_USB_SERIAL_PL2303_GPIO
+static int pl2303_gpio_startup(struct usb_serial *serial);
+static void pl2303_gpio_release(struct usb_serial *serial);
+#else
+static inline int pl2303_gpio_startup(struct usb_serial *serial) { return 0; }
+static inline void pl2303_gpio_release(struct usb_serial *serial) {}
+#endif
+
 static const struct pl2303_type_data pl2303_type_data[TYPE_COUNT] = {
 	[TYPE_01] = {
 		.max_baud_rate =	1228800,
@@ -214,11 +243,213 @@ static int pl2303_probe(struct usb_serial *serial,
 	return 0;
 }
 
+#ifdef CONFIG_USB_SERIAL_PL2303_GPIO
+struct pl2303_gpio_desc {
+	u8 dir_offset;
+	u8 dir_mask;
+	u16 dir_ctrl;
+	u8 value_offset;
+	u8 value_mask;
+	u16 value_ctrl;
+	u16 read_ctrl;
+};
+
+struct pl2303_gpio {
+	struct pl2303_gpio_desc *descs;
+	u8 data[3];
+	struct mutex lock;
+	struct usb_serial *serial;
+	struct gpio_chip gpio_chip;
+};
+
+static inline struct pl2303_gpio *to_pl2303_gpio(struct gpio_chip *chip)
+{
+	return container_of(chip, struct pl2303_gpio, gpio_chip);
+}
+
+static void pl2303_gpio_add(struct usb_serial *serial, u8 num, u16 read_ctrl,
+			u8 dir_offset, u8 dir_mask, u16 dir_ctrl,
+			u8 value_offset, u8 value_mask, u16 value_ctrl)
+{
+	struct pl2303_serial_private *spriv = usb_get_serial_data(serial);
+	struct pl2303_gpio *gpio = spriv->gpio;
+
+	BUG_ON(num >= spriv->ngpio);
+	gpio->descs[num].dir_offset = dir_offset;
+	gpio->descs[num].dir_mask = dir_mask;
+	gpio->descs[num].dir_ctrl = dir_ctrl;
+
+	gpio->descs[num].value_offset = value_offset;
+	gpio->descs[num].value_mask = value_mask;
+	gpio->descs[num].value_ctrl = value_ctrl;
+
+	gpio->descs[num].read_ctrl = read_ctrl;
+}
+
+static int pl2303_gpio_direction_in(struct gpio_chip *chip, unsigned offset)
+{
+	struct pl2303_gpio *gpio = to_pl2303_gpio(chip);
+	struct pl2303_gpio_desc *desc;
+	int ret;
+
+	mutex_lock(&gpio->lock);
+	desc = gpio->descs+offset;
+	gpio->data[desc->dir_offset] &= ~desc->dir_mask;
+	ret = pl2303_vendor_write(gpio->serial, desc->dir_ctrl,
+				gpio->data[desc->dir_offset]);
+	mutex_unlock(&gpio->lock);
+
+	return ret;
+}
+
+static int pl2303_gpio_direction_out(struct gpio_chip *chip,
+				unsigned offset, int value)
+{
+	struct pl2303_gpio *gpio = to_pl2303_gpio(chip);
+	struct pl2303_gpio_desc *desc;
+	int ret;
+
+	mutex_lock(&gpio->lock);
+	desc = gpio->descs+offset;
+	gpio->data[desc->dir_offset] |= desc->dir_mask;
+	ret = pl2303_vendor_write(gpio->serial, desc->dir_ctrl,
+				gpio->data[desc->dir_offset]);
+	if (ret)
+		goto error;
+
+	if (value)
+		gpio->data[desc->value_offset] |= desc->value_mask;
+	else
+		gpio->data[desc->value_offset] &= ~desc->value_mask;
+
+	ret = pl2303_vendor_write(gpio->serial, desc->value_ctrl,
+				gpio->data[desc->value_offset]);
+error:
+	mutex_unlock(&gpio->lock);
+
+	return ret;
+}
+
+static void pl2303_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+	struct pl2303_gpio *gpio = to_pl2303_gpio(chip);
+	struct pl2303_gpio_desc *desc;
+
+	mutex_lock(&gpio->lock);
+	desc = gpio->descs+offset;
+	if (value)
+		gpio->data[desc->value_offset] |= desc->value_mask;
+	else
+		gpio->data[desc->value_offset] &= ~desc->value_mask;
+
+	pl2303_vendor_write(gpio->serial, desc->value_ctrl,
+			gpio->data[desc->value_offset]);
+	mutex_unlock(&gpio->lock);
+}
+
+static int pl2303_gpio_get(struct gpio_chip *chip, unsigned offset)
+{
+	struct pl2303_gpio *gpio = to_pl2303_gpio(chip);
+	struct pl2303_gpio_desc *desc;
+	unsigned char *buf;
+	int value;
+
+	buf = kzalloc(1, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	mutex_lock(&gpio->lock);
+	desc = gpio->descs+offset;
+
+	if (pl2303_vendor_read(gpio->serial, desc->read_ctrl, buf)) {
+		mutex_unlock(&gpio->lock);
+		return -EIO;
+	}
+
+	value = buf[0] & desc->value_mask;
+	mutex_unlock(&gpio->lock);
+	kfree(buf);
+
+	return value;
+}
+
+static int pl2303_gpio_startup(struct usb_serial *serial)
+{
+	struct pl2303_serial_private *spriv = usb_get_serial_data(serial);
+	struct pl2303_gpio *gpio;
+	int ret;
+
+	gpio = kzalloc(sizeof(struct pl2303_gpio), GFP_KERNEL);
+	if (!gpio)
+		return -ENOMEM;
+
+	gpio->descs = kcalloc(spriv->ngpio, sizeof(struct pl2303_gpio_desc),
+			GFP_KERNEL);
+	if (!gpio->descs) {
+		kfree(gpio);
+		return -ENOMEM;
+	}
+	spriv->gpio = gpio;
+
+	pl2303_gpio_add(serial, 0, HXD_GPIO_01_VALUE,
+			0, HXD_GPIO0_DIR_MASK, HXD_GPIO_01_CTRL,
+			0, HXD_GPIO0_VALUE_MASK, HXD_GPIO_01_CTRL);
+	pl2303_gpio_add(serial, 1, HXD_GPIO_01_VALUE,
+			0, HXD_GPIO1_DIR_MASK, HXD_GPIO_01_CTRL,
+			0, HXD_GPIO1_VALUE_MASK, HXD_GPIO_01_CTRL);
+
+	if (spriv->ngpio == 4) {
+		pl2303_gpio_add(serial, 2, HXD_GPIO_23_VALUE,
+				1, HXD_GPIO2_DIR_MASK, HXD_GPIO_23_DIR_CTRL,
+				2, HXD_GPIO2_VALUE_MASK,
+				HXD_GPIO_23_VALUE_CTRL);
+		pl2303_gpio_add(serial, 3, HXD_GPIO_23_VALUE,
+				1, HXD_GPIO3_DIR_MASK, HXD_GPIO_23_DIR_CTRL,
+				2, HXD_GPIO3_VALUE_MASK,
+				HXD_GPIO_23_VALUE_CTRL);
+	}
+
+	gpio->serial = serial;
+	mutex_init(&gpio->lock);
+
+	gpio->gpio_chip.label = "pl2303";
+	gpio->gpio_chip.owner = THIS_MODULE;
+	gpio->gpio_chip.direction_input = pl2303_gpio_direction_in;
+	gpio->gpio_chip.get = pl2303_gpio_get;
+	gpio->gpio_chip.direction_output = pl2303_gpio_direction_out;
+	gpio->gpio_chip.set = pl2303_gpio_set;
+	gpio->gpio_chip.can_sleep  = true;
+	gpio->gpio_chip.ngpio = spriv->ngpio;
+	gpio->gpio_chip.base = -1;
+	gpio->gpio_chip.dev = &serial->interface->dev;
+
+	ret = gpiochip_add(&gpio->gpio_chip);
+	if (ret < 0) {
+		kfree(gpio);
+		return ret;
+	}
+	return 0;
+}
+
+static void pl2303_gpio_release(struct usb_serial *serial)
+{
+	struct pl2303_serial_private *spriv = usb_get_serial_data(serial);
+	struct pl2303_gpio *gpio = (struct pl2303_gpio *)spriv->gpio;
+
+	gpiochip_remove(&gpio->gpio_chip);
+	kfree(gpio->descs);
+	kfree(gpio);
+}
+#endif
+
 static int pl2303_startup(struct usb_serial *serial)
 {
 	struct pl2303_serial_private *spriv;
 	enum pl2303_type type = TYPE_01;
 	unsigned char *buf;
+	u16 bcdDevice;
+	u8 major_revision;
+	int ret;
 
 	spriv = kzalloc(sizeof(*spriv), GFP_KERNEL);
 	if (!spriv)
@@ -244,6 +475,16 @@ static int pl2303_startup(struct usb_serial *serial)
 	spriv->quirks = (unsigned long)usb_get_serial_data(serial);
 	spriv->quirks |= spriv->type->quirks;
 
+	spriv->ngpio = 0;
+	if (type == TYPE_HX) {
+		bcdDevice = le16_to_cpu(serial->dev->descriptor.bcdDevice);
+		major_revision = bcdDevice = bcdDevice >> 8;
+		if (major_revision == 3)
+			spriv->ngpio = 2;
+		else if (major_revision == 4)
+			spriv->ngpio = 4;
+	}
+
 	usb_set_serial_data(serial, spriv);
 
 	pl2303_vendor_read(serial, 0x8484, buf);
@@ -263,6 +504,13 @@ static int pl2303_startup(struct usb_serial *serial)
 
 	kfree(buf);
 
+	if (spriv->ngpio > 0) {
+		ret = pl2303_gpio_startup(serial);
+		if (ret) {
+			kfree(spriv);
+			return ret;
+		}
+	}
 	return 0;
 }
 
@@ -270,6 +518,8 @@ static void pl2303_release(struct usb_serial *serial)
 {
 	struct pl2303_serial_private *spriv = usb_get_serial_data(serial);
 
+	if (spriv->ngpio > 0)
+		pl2303_gpio_release(serial);
 	kfree(spriv);
 }
 
-- 
1.8.5.5.dirty