Re: [RESEND PATCH v5 1/1] USB: serial: cp210x: Adding GPIO support for CP2105

[Martyn Welch <martyn.welch-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>]

On Sat, Aug 20, 2016 at 02:06:29PM +0200, Johan Hovold wrote:
> [ +CC: Karl and Konstantin ]
> 
> On Fri, Jul 22, 2016 at 11:33:15AM +0100, Martyn Welch wrote:
> > This patch adds support for the GPIO found on the CP2105. Unlike the GPIO
> > provided by some of the other devices supported by the cp210x driver, the
> > GPIO on the CP2015 is muxed on pins otherwise used for serial control
> > lines. The GPIO have been configured in 2 separate banks as the choice to
> > configure the pins for GPIO is made separately for pins shared with each
> > of the 2 serial ports this device provides, though the choice is made for
> > all pins associated with that port in one go. The choice of whether to use
> > the pins for GPIO or serial is made by adding configuration to a one-time
> > programable PROM in the chip and can not be changed at runtime. The device
> > defaults to GPIO.
> > 
> > This device supports either push-pull or open-drain modes, it doesn't
> > provide an explicit input mode, though the state of the GPIO can be read
> > when used in open-drain mode. Like with pin use, the mode is configured in
> > the one-time programable PROM and can't be changed at runtime.
> > 
> > Signed-off-by: Martyn Welch <martyn.welch-ZGY8ohtN/8pPYcu2f3hruQ@public.gmane.org>
> > Acked-by: Linus Walleij <linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> > ---
> > 
> > V2: - Doesn't break build when gpiolib isn't selected.
> > 
> > V3: - Tracking GPIO state so pins no longer get their state changed should
> >       the pin be in open-drain mode and be pulled down externally whilst
> >       another pin is set.
> >     - Reworked buffers and moved to byte accesses to remove the
> >       questionable buffer size logic and byte swapping.
> >     - Added error reporting.
> >     - Removed incorrect/pointless comments.
> >     - Renamed tmp variable to make use clearer.
> > 
> > V4: - Fixed memory leak in cp210x_gpio_get error path.
> > 
> > V5: - Determining shared GPIO based on device type.
> >     - Reordered vendor specific values by value.
> >     - Use interface device for gpio messages.
> >     - Remove unnecessary empty lines.
> >     - Using kzalloc rather than kcalloc.
> >     - Added locking to port_priv->output_state.
> >     - Added dummy cp2105_shared_gpio_init for !CONFIG_GPIOLIB.
> >     - Removed unnecessary masking on u8.
> >     - Added support for use of GPIO pin as RS485 traffic indication or
> >       activity LEDs.
> >     - Use correct dev for GPIO device.
> >     - Set can_sleep.
> >     - Roll in initial configuration state support.
> >     - Print error message & continue if GPIO fails.
> >     - Simplified ifdef'ing.
> 
> My apologies for the extreme delay for v5 review.
> 

Sorry for the delayed response too.

> >  drivers/usb/serial/cp210x.c | 351 +++++++++++++++++++++++++++++++++++++++++++-
> >  1 file changed, 348 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
> > index 4d6a5c6..b3153b8 100644
> > --- a/drivers/usb/serial/cp210x.c
> > +++ b/drivers/usb/serial/cp210x.c
> > @@ -23,6 +23,9 @@
> >  #include <linux/usb.h>
> >  #include <linux/uaccess.h>
> >  #include <linux/usb/serial.h>
> > +#include <linux/gpio/driver.h>
> > +#include <linux/bitops.h>
> > +#include <linux/mutex.h>
> >  
> >  #define DRIVER_DESC "Silicon Labs CP210x RS232 serial adaptor driver"
> >  
> > @@ -44,10 +47,14 @@ static int cp210x_tiocmset(struct tty_struct *, unsigned int, unsigned int);
> >  static int cp210x_tiocmset_port(struct usb_serial_port *port,
> >  		unsigned int, unsigned int);
> >  static void cp210x_break_ctl(struct tty_struct *, int);
> > +static int cp210x_attach(struct usb_serial *);
> > +static void cp210x_release(struct usb_serial *);
> >  static int cp210x_port_probe(struct usb_serial_port *);
> >  static int cp210x_port_remove(struct usb_serial_port *);
> >  static void cp210x_dtr_rts(struct usb_serial_port *p, int on);
> >  
> > +#define CP210X_FEATURE_HAS_SHARED_GPIO		BIT(0)
> 
> This one is not currently used, so should be removed.
> 

Agh, oops, missed that.

> > +
> >  static const struct usb_device_id id_table[] = {
> >  	{ USB_DEVICE(0x045B, 0x0053) }, /* Renesas RX610 RX-Stick */
> >  	{ USB_DEVICE(0x0471, 0x066A) }, /* AKTAKOM ACE-1001 cable */
> > @@ -207,9 +214,20 @@ static const struct usb_device_id id_table[] = {
> >  
> >  MODULE_DEVICE_TABLE(usb, id_table);
> >  
> > +struct cp210x_dev_private {
> 
> Rename this cp210x_serial_private.
> 

OK

> > +	u8	partnum;
> > +};
> > +
> >  struct cp210x_port_private {
> >  	__u8			bInterfaceNumber;
> >  	bool			has_swapped_line_ctl;
> > +#ifdef CONFIG_GPIOLIB
> > +	struct usb_serial	*serial;
> > +	struct gpio_chip	gc;
> > +	struct mutex		output_lock;
> > +	unsigned int		output_state;
> > +	unsigned int		*gpio_map;
> > +#endif
> 
> As mentioned in my comments to v4, these belong in the interface private
> data (i.e. private data of the parent device).
> 

Ah, sorry.

> >  };
> >  
> >  static struct usb_serial_driver cp210x_device = {
> > @@ -228,6 +246,8 @@ static struct usb_serial_driver cp210x_device = {
> >  	.tx_empty		= cp210x_tx_empty,
> >  	.tiocmget		= cp210x_tiocmget,
> >  	.tiocmset		= cp210x_tiocmset,
> > +	.attach			= cp210x_attach,
> > +	.release		= cp210x_release,
> >  	.port_probe		= cp210x_port_probe,
> >  	.port_remove		= cp210x_port_remove,
> >  	.dtr_rts		= cp210x_dtr_rts
> > @@ -270,6 +290,7 @@ static struct usb_serial_driver * const serial_drivers[] = {
> >  #define CP210X_SET_CHARS	0x19
> >  #define CP210X_GET_BAUDRATE	0x1D
> >  #define CP210X_SET_BAUDRATE	0x1E
> > +#define CP210X_VENDOR_SPECIFIC	0xFF
> >  
> >  /* CP210X_IFC_ENABLE */
> >  #define UART_ENABLE		0x0001
> > @@ -312,6 +333,30 @@ static struct usb_serial_driver * const serial_drivers[] = {
> >  #define CONTROL_WRITE_DTR	0x0100
> >  #define CONTROL_WRITE_RTS	0x0200
> >  
> > +/* CP210X_VENDOR_SPECIFIC values */
> > +#define CP210X_READ_LATCH	0x00C2
> > +#define CP210X_GET_PARTNUM	0x370B
> > +#define CP210X_GET_PORTCONFIG	0x370C
> > +#define CP210X_GET_DEVICEMODE	0x3711
> > +#define CP210X_WRITE_LATCH	0x37E1
> > +
> > +/* Part number definitions */
> > +#define CP2101_PARTNUM		0x01
> > +#define CP2102_PARTNUM		0x02
> > +#define CP2103_PARTNUM		0x03
> > +#define CP2104_PARTNUM		0x04
> > +#define CP2105_PARTNUM		0x05
> > +#define CP2108_PARTNUM		0x08
> 
> Please use a CP210X_ prefix, and rename these CP210X_PARTNUM_CP2101,
> etc.
> 

OK

> > +
> > +/* CP2105 port configuration values */
> > +#define CP2105_SCI_GPIO0_TXLED_MODE	0x01
> > +#define CP2105_SCI_GPIO1_RXLED_MODE	0x02
> > +
> > +
> 
> Remove one newline.
> 

OK

> > +#define CP2105_ECI_GPIO0_TXLED_MODE	0x01
> > +#define CP2105_ECI_GPIO1_RXLED_MODE	0x02
> > +#define CP2105_ECI_GPIO1_RS485_MODE	0x04
> 
> If all of these are bitmasks, you should use BIT(n).
> 

I guess they are - will convert.

> Also move all of these vendor-specific defines last (i.e. above
> cp210x_read_reg_block).
> 

OK

> > +
> >  /* CP210X_GET_COMM_STATUS returns these 0x13 bytes */
> >  struct cp210x_comm_status {
> >  	__le32   ulErrors;
> > @@ -1104,11 +1149,263 @@ static void cp210x_break_ctl(struct tty_struct *tty, int break_state)
> >  	cp210x_write_u16_reg(port, CP210X_SET_BREAK, state);
> >  }
> >  
> > +#ifdef CONFIG_GPIOLIB
> > +static int cp210x_gpio_direction_get(struct gpio_chip *gc, unsigned gpio)
> > +{
> > +	return 0;
> > +}
> > +
> > +static int cp210x_gpio_get(struct gpio_chip *gc, unsigned gpio)
> > +{
> > +	struct cp210x_port_private *port_priv =
> > +			 container_of(gc, struct cp210x_port_private, gc);
> 
> Just use tabs for indentation here.
> 

OK

> > +	struct usb_serial *serial = port_priv->serial;
> > +	u8 *buf;
> > +	int result;
> > +
> > +	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
> > +	if (!buf)
> > +		return -ENOMEM;
> > +
> > +	result = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
> > +				 CP210X_VENDOR_SPECIFIC,
> > +				 REQTYPE_INTERFACE_TO_HOST, CP210X_READ_LATCH,
> > +				 port_priv->bInterfaceNumber, buf, 1,
> > +				 USB_CTRL_GET_TIMEOUT);
> 
> Please consider adding generic helpers for these vendor requests as that
> would allow you to remove a lot of the buffer-management code.
> 
> We could even consider using those to implement the current reg_block
> helpers later.
> 
> > +	if (result != 1) {
> > +		dev_err(&serial->interface->dev,
> > +			"failed to get gpio state: %d\n", result);
> > +		result = 0;
> > +		goto err;
> > +	}
> > +
> > +	result = (*buf >> port_priv->gpio_map[gpio]) & 0x1;
> > +
> > +err:
> > +	kfree(buf);
> > +
> > +	return result;
> > +}
> > +
> > +static void cp210x_gpio_set(struct gpio_chip *gc, unsigned gpio, int value)
> > +{
> > +	struct cp210x_port_private *port_priv =
> > +			 container_of(gc, struct cp210x_port_private, gc);
> > +	struct usb_serial *serial = port_priv->serial;
> > +	int result;
> > +	u8 *buf;
> > +
> > +	buf = kzalloc(sizeof(*buf) * 2, GFP_KERNEL);
> > +	if (!buf)
> > +		return;
> > +
> > +	mutex_lock(&port_priv->output_lock);
> > +
> > +	if (value == 0)
> > +		port_priv->output_state &= ~BIT(port_priv->gpio_map[gpio]);
> > +	else
> > +		port_priv->output_state |= BIT(port_priv->gpio_map[gpio]);
> > +
> > +	mutex_unlock(&port_priv->output_lock);
> > +
> > +	buf[1] = port_priv->output_state;
> > +	buf[0] = 0xFF;
> 
> You should consider using a struct for this message instead of a raw
> byte array. Perhaps the field names could be found in one of those
> SiLabs application notes.
> 

I'll have a look, but I think they just used raw byte arrays from memory.

> > +
> > +	result = usb_control_msg(serial->dev,
> > +				 usb_sndctrlpipe(serial->dev, 0),
> > +				 CP210X_VENDOR_SPECIFIC,
> > +				 REQTYPE_HOST_TO_INTERFACE, CP210X_WRITE_LATCH,
> > +				 port_priv->bInterfaceNumber, buf, 2,
> > +				 USB_CTRL_SET_TIMEOUT);
> > +	if (result != 2) {
> > +		dev_err(&serial->interface->dev,
> > +			"failed to set gpio state: %d\n", result);
> > +	}
> > +
> > +	kfree(buf);
> > +}
> > +
> > +/*
> > + * This function is for configuring GPIO using shared pins, where other signals
> > + * are made unavailable by configuring the use of GPIO. This is believed to be
> > + * only applicable to the cp2105 at this point, the other devices supported by
> > + * this driver that provide GPIO do so in a way that does not impact other
> > + * signals and are thus expected to have very different initialisation.
> > + */
> 
> Instead of exposing a varying number of gpios and hence varying chip
> offsets depending on current configuration, I think we should always
> register all gpios and instead (possibly) refuse requests for them in
> case the corresponding pin is currently not configured for gpio
> function.
> 
> This way gpio base+offset will always map to the same physical pin.
> 
> Judging from the various cp210x datasheets, this scheme will fit the
> other device types as well.
> 

I'd like to hear Linus' take on that prior to making that change as I'd
prefer not to do it then have him NACK it. Linus?

> > +static int cp2105_shared_gpio_init(struct usb_serial_port *port)
> > +{
> > +	struct usb_serial *serial = port->serial;
> > +	struct cp210x_port_private *port_priv = usb_get_serial_port_data(port);
> > +	u8 *mode;
> > +	u8 *config;
> > +	int result;
> > +	int i;
> > +
> > +	mode = kzalloc(sizeof(*mode) * 2, GFP_KERNEL);
> > +	if (!mode)
> > +		return -ENOMEM;
> > +
> > +	config = kzalloc(sizeof(*config) * 15, GFP_KERNEL);
> > +	if (!config) {
> > +		result = -ENOMEM;
> > +		goto err1;
> > +	}
> 
> Same as above, please use packed structs for these messages too instead
> of hard-coding sizes and offsets (cf. struct cp210x_comm_status).
> 
> I think I saw some more structure to them in Karl's OTP scripts, and
> perhaps Konstantin can also provide some insight?
> 

Ok, will take a look.

> > +
> > +	result = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
> > +				 CP210X_VENDOR_SPECIFIC, REQTYPE_DEVICE_TO_HOST,
> > +				 CP210X_GET_DEVICEMODE,
> > +				 port_priv->bInterfaceNumber, mode,
> > +				 2, USB_CTRL_GET_TIMEOUT);
> > +	if (result != 2) {
> > +		dev_err(&port->dev, "failed to get device mode: %d\n", result);
> > +		if (result > 0)
> > +			result = -EPROTO;
> > +
> > +		goto err2;
> > +	}
> > +
> > +	result = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
> > +				 CP210X_VENDOR_SPECIFIC, REQTYPE_DEVICE_TO_HOST,
> > +				 CP210X_GET_PORTCONFIG,
> > +				 port_priv->bInterfaceNumber, config, 15,
> > +				 USB_CTRL_GET_TIMEOUT);
> > +	if (result != 15) {
> > +		dev_err(&port->dev, "failed to get port config: %d\n", result);
> > +		if (result > 0)
> > +			result = -EPROTO;
> > +
> > +		goto err2;
> > +	}
> > +
> > +	/*  2 banks of GPIO - One for the pins taken from each serial port */
> > +	if (port_priv->bInterfaceNumber == 0) {
> > +		if (mode[0] == 0) {
> > +			result = 0;
> > +			goto err2;
> > +		}
> > +
> > +		port_priv->gc.label = "cp210x_eci";
> > +		port_priv->gc.ngpio = 2;
> > +		port_priv->gpio_map = kzalloc(sizeof(*port_priv->gpio_map) *
> > +					      port_priv->gc.ngpio,
> > +					      GFP_KERNEL);
> 
> You must check for allocation failures.
> 
> I don't think you'll need gpio_map at all if you always register all
> gpios.
> 
> You may want a single bitmask to store which pins are configured for
> gpio-function, and use that in a new request() callback instead.
> 
> Just use the same label for all cp210x gpiochips, there will never be
> more than one per interface anyway.
> 

OK

> > +
> > +		i = 0;
> > +
> > +		if (config[13] & CP2105_ECI_GPIO0_TXLED_MODE) {
> > +			port_priv->gc.ngpio -= 1;
> > +		} else {
> > +			port_priv->gpio_map[i] = 0;
> > +			i++;
> > +		}
> > +
> > +		if (config[13] & (CP2105_ECI_GPIO1_RXLED_MODE |
> > +				  CP2105_ECI_GPIO1_RS485_MODE)) {
> > +			port_priv->gc.ngpio -= 1;
> > +		} else {
> > +			port_priv->gpio_map[i] = 1;
> > +			i++;
> > +		}
> > +
> > +		if (port_priv->gc.ngpio == 0) {
> > +			result = 0;
> > +			goto err2;
> > +		}
> > +	} else if (port_priv->bInterfaceNumber == 1) {
> > +		if (mode[1] == 0) {
> > +			result = 0;
> > +			goto err2;
> > +		}
> > +
> > +		port_priv->gc.label = "cp210x_sci";
> > +		port_priv->gc.ngpio = 3;
> > +		port_priv->gpio_map = kzalloc(sizeof(*port_priv->gpio_map) *
> > +					      port_priv->gc.ngpio,
> > +					      GFP_KERNEL);
> 
> Error handling missing here too.
> 

OK

> > +
> > +		i = 0;
> > +
> > +		if (config[12] & CP2105_SCI_GPIO0_TXLED_MODE) {
> > +			port_priv->gc.ngpio -= 1;
> > +		} else {
> > +			port_priv->gpio_map[i] = 0;
> > +			i++;
> > +		}
> > +
> > +		if (config[12] & CP2105_SCI_GPIO1_RXLED_MODE) {
> > +			port_priv->gc.ngpio -= 1;
> > +		} else {
> > +			port_priv->gpio_map[i] = 1;
> > +			i++;
> > +		}
> > +
> > +		port_priv->gpio_map[i] = 2;
> > +	} else {
> > +		result = -ENODEV;
> > +		goto err2;
> > +	}
> > +
> > +	port_priv->gc.get_direction = cp210x_gpio_direction_get;
> > +	port_priv->gc.get = cp210x_gpio_get;
> > +	port_priv->gc.set = cp210x_gpio_set;
> > +	port_priv->gc.owner = THIS_MODULE;
> > +	port_priv->gc.parent = &serial->interface->dev;
> > +	port_priv->gc.base = -1;
> > +	port_priv->gc.can_sleep = true;
> > +
> > +	port_priv->serial = serial;
> > +
> > +	/*
> > +	 * Need to track the state of the output pins, the read function
> > +	 * returns value seen on the pin, not the value being currently
> > +	 * driven.
> > +	 */
> > +	if (port_priv->bInterfaceNumber == 0)
> > +		port_priv->output_state = (config[4] >> 2) & 0x3;
> > +	else
> > +		port_priv->output_state = (config[5] >> 1) & 0x7;
> > +
> > +	mutex_init(&port_priv->output_lock);
> > +
> > +	result = gpiochip_add(&port_priv->gc);
> > +
> > +err2:
> 
> Please rename these out_free_config...
> 

OK

> > +	kfree(config);
> > +err1:
> 
> ...and out_free_mode, which is more descriptive.
> 

OK

> > +	kfree(mode);
> > +
> > +	return result;
> > +}
> > +
> > +void cp210x_shared_gpio_remove(struct usb_serial_port *port)
> > +{
> > +	struct cp210x_port_private *port_priv;
> > +
> > +	port_priv = usb_get_serial_port_data(port);
> > +
> > +	if (port_priv->gc.label)
> > +		gpiochip_remove(&port_priv->gc);
> 
> This can be done unconditionally after the changes suggested above.
> 
> > +}
> > +
> > +#else
> > +
> > +static int cp2105_shared_gpio_init(struct usb_serial_port *port)
> > +{
> > +	return 0;
> > +}
> > +
> > +void cp210x_shared_gpio_remove(struct usb_serial_port *port)
> > +{
> > +	/* Nothing to do */
> > +}
> > +#endif
> > +
> >  static int cp210x_port_probe(struct usb_serial_port *port)
> >  {
> >  	struct usb_serial *serial = port->serial;
> >  	struct usb_host_interface *cur_altsetting;
> >  	struct cp210x_port_private *port_priv;
> > +	struct cp210x_dev_private *dev_priv = usb_get_serial_data(serial);
> >  	int ret;
> >  
> >  	port_priv = kzalloc(sizeof(*port_priv), GFP_KERNEL);
> > @@ -1121,12 +1418,22 @@ static int cp210x_port_probe(struct usb_serial_port *port)
> >  	usb_set_serial_port_data(port, port_priv);
> >  
> >  	ret = cp210x_detect_swapped_line_ctl(port);
> > -	if (ret) {
> > -		kfree(port_priv);
> > -		return ret;
> > +	if (ret)
> > +		goto err_ctl;
> > +
> > +	if (dev_priv->partnum == CP2105_PARTNUM) {
> > +		ret = cp2105_shared_gpio_init(port);
> > +		if (ret < 0)
> > +			dev_err(&port->dev,
> > +				"GPIO initialisation failed, continuing without GPIO support\n");
> >  	}
> 
> So move this to attach().
> 

OK

> >  
> >  	return 0;
> > +
> > +err_ctl:
> > +	kfree(port_priv);
> > +
> > +	return ret;
> >  }
> >  
> >  static int cp210x_port_remove(struct usb_serial_port *port)
> > @@ -1134,11 +1441,49 @@ static int cp210x_port_remove(struct usb_serial_port *port)
> >  	struct cp210x_port_private *port_priv;
> >  
> >  	port_priv = usb_get_serial_port_data(port);
> > +
> > +	cp210x_shared_gpio_remove(port);
> > +
> >  	kfree(port_priv);
> >  
> >  	return 0;
> >  }
> >  
> > +static int cp210x_attach(struct usb_serial *serial)
> > +{
> > +	struct cp210x_dev_private *priv;
> > +	int result;
> > +
> > +	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> > +	if (!priv)
> > +		return -ENOMEM;
> > +
> > +	result = usb_control_msg(serial->dev, usb_rcvctrlpipe(serial->dev, 0),
> > +				 CP210X_VENDOR_SPECIFIC, REQTYPE_DEVICE_TO_HOST,
> > +				 CP210X_GET_PARTNUM, 0, &priv->partnum, 1,
> 
> Always use a dedicated DMA-able buffer for transfers like this one.
> Adding a couple of helper function for this as suggested above, would
> take care of that.
> 

OK

> > +				 USB_CTRL_GET_TIMEOUT);
> > +	if (result != 1) {
> > +		dev_err(&serial->interface->dev, "failed to get model: %d\n",
> > +			result);
> > +		goto err;
> > +	}
> > +
> > +	usb_set_serial_data(serial, (void *)priv);
> > +
> > +	return 0;
> > +err:
> > +	kfree(priv);
> > +
> > +	return result;
> > +}
> > +
> > +static void cp210x_release(struct usb_serial *serial)
> > +{
> > +	struct cp210x_dev_private *priv = usb_get_serial_data(serial);
> > +
> > +	kfree(priv);
> > +}
> > +
> >  module_usb_serial_driver(serial_drivers, id_table);
> >  
> >  MODULE_DESCRIPTION(DRIVER_DESC);
> 
> Thanks,
> Johan
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