Major improvements to the ch341 driver v3

Major improvements to the ch341 driver v3

[Grigori Goronzy]

Hi,

here's a revised v3 of my ch341 patchset sent earlier this month.
Thanks to everyone who provided feedback.  Changes compared to the
last submission have been indicated in the commit messages.

Please review.

Best regards
Grigori

[PATCH v3 01/13] USB: ch341: fix error handling on resume

[Grigori Goronzy]

This may fail, do not assume it always works.

Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
---
 drivers/usb/serial/ch341.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index c73808f..63df8ce 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -544,9 +544,7 @@ static int ch341_reset_resume(struct usb_serial *serial)
 	priv = usb_get_serial_port_data(serial->port[0]);
 
 	/* reconfigure ch341 serial port after bus-reset */
-	ch341_configure(serial->dev, priv);
-
-	return 0;
+	return ch341_configure(serial->dev, priv);
 }
 
 static struct usb_serial_driver ch341_device = {
-- 
1.9.1

[PATCH v3 02/13] USB: ch341: add LCR register definitions

[Grigori Goronzy]

BREAK2 seems to be a misnomer, the register configures various aspects
of the UART configuration.

Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
---
 drivers/usb/serial/ch341.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 63df8ce..1ab4384 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -64,10 +64,19 @@
 #define CH341_REQ_WRITE_REG    0x9A
 #define CH341_REQ_READ_REG     0x95
 #define CH341_REG_BREAK1       0x05
-#define CH341_REG_BREAK2       0x18
+#define CH341_REG_LCR          0x18
 #define CH341_NBREAK_BITS_REG1 0x01
-#define CH341_NBREAK_BITS_REG2 0x40
 
+#define CH341_LCR_ENABLE_RX    0x80
+#define CH341_LCR_ENABLE_TX    0x40
+#define CH341_LCR_MARK_SPACE   0x20
+#define CH341_LCR_PAR_EVEN     0x10
+#define CH341_LCR_ENABLE_PAR   0x08
+#define CH341_LCR_STOP_BITS_2  0x04
+#define CH341_LCR_CS8          0x03
+#define CH341_LCR_CS7          0x02
+#define CH341_LCR_CS6          0x01
+#define CH341_LCR_CS5          0x00
 
 static const struct usb_device_id id_table[] = {
 	{ USB_DEVICE(0x4348, 0x5523) },
@@ -370,7 +379,7 @@ static void ch341_set_termios(struct tty_struct *tty,
 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
 {
 	const uint16_t ch341_break_reg =
-		CH341_REG_BREAK1 | ((uint16_t) CH341_REG_BREAK2 << 8);
+		CH341_REG_BREAK1 | ((uint16_t) CH341_REG_LCR << 8);
 	struct usb_serial_port *port = tty->driver_data;
 	int r;
 	uint16_t reg_contents;
@@ -392,11 +401,11 @@ static void ch341_break_ctl(struct tty_struct *tty, int break_state)
 	if (break_state != 0) {
 		dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
 		break_reg[0] &= ~CH341_NBREAK_BITS_REG1;
-		break_reg[1] &= ~CH341_NBREAK_BITS_REG2;
+		break_reg[1] &= ~CH341_LCR_ENABLE_TX;
 	} else {
 		dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
 		break_reg[0] |= CH341_NBREAK_BITS_REG1;
-		break_reg[1] |= CH341_NBREAK_BITS_REG2;
+		break_reg[1] |= CH341_LCR_ENABLE_TX;
 	}
 	dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
 		__func__, break_reg[0], break_reg[1]);
-- 
1.9.1

[PATCH v3 03/13] USB: ch341: add definitions for modem control

[Grigori Goronzy]

Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
---
 drivers/usb/serial/ch341.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 1ab4384..db4b561 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -61,6 +61,7 @@
  * the Net/FreeBSD uchcom.c driver by Takanori Watanabe.  Domo arigato.
  */
 
+#define CH341_MODEM_CTRL       0xA4
 #define CH341_REQ_WRITE_REG    0x9A
 #define CH341_REQ_READ_REG     0x95
 #define CH341_REG_BREAK1       0x05
@@ -162,7 +163,7 @@ static int ch341_set_baudrate(struct usb_device *dev,
 
 static int ch341_set_handshake(struct usb_device *dev, u8 control)
 {
-	return ch341_control_out(dev, 0xa4, ~control, 0);
+	return ch341_control_out(dev, CH341_MODEM_CTRL, ~control, 0);
 }
 
 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
-- 
1.9.1

[PATCH v3 04/13] USB: ch341: fix USB buffer allocations

[Grigori Goronzy]

Use the correct types and sizes.

v2: use u8 shorthand for unsigned char.

Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
---
 drivers/usb/serial/ch341.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index db4b561..95c8a40 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -115,7 +115,7 @@ static int ch341_control_out(struct usb_device *dev, u8 request,
 
 static int ch341_control_in(struct usb_device *dev,
 			    u8 request, u16 value, u16 index,
-			    char *buf, unsigned bufsize)
+			    u8 *buf, unsigned bufsize)
 {
 	int r;
 
@@ -168,9 +168,9 @@ static int ch341_set_handshake(struct usb_device *dev, u8 control)
 
 static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 {
-	char *buffer;
+	unsigned char *buffer;
 	int r;
-	const unsigned size = 8;
+	const unsigned size = 2;
 	unsigned long flags;
 
 	buffer = kmalloc(size, GFP_KERNEL);
@@ -198,9 +198,9 @@ out:	kfree(buffer);
 
 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 {
-	char *buffer;
+	unsigned char *buffer;
 	int r;
-	const unsigned size = 8;
+	const unsigned size = 2;
 
 	buffer = kmalloc(size, GFP_KERNEL);
 	if (!buffer)
-- 
1.9.1

[PATCH v3 05/13] USB: ch341: reinitialize chip on reconfiguration

[Grigori Goronzy]

Changing the LCR register after initialization does not seem to be
reliable on all chips (particularly not on CH341A).  Restructure
initialization and configuration to always reinit the chip on
configuration changes instead and pass the LCR register value directly
to the initialization command.

v2: get rid of unused variable, improve error handling.

Tested-by: Ryan Barber <rfb@skyscraper.nu>
Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
---
 drivers/usb/serial/ch341.c | 47 ++++++++++++++++++++++++----------------------
 1 file changed, 25 insertions(+), 22 deletions(-)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 95c8a40..6181616 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -61,6 +61,8 @@
  * the Net/FreeBSD uchcom.c driver by Takanori Watanabe.  Domo arigato.
  */
 
+#define CH341_SERIAL_INIT      0xA1
+#define CH341_VERSION          0x5F
 #define CH341_MODEM_CTRL       0xA4
 #define CH341_REQ_WRITE_REG    0x9A
 #define CH341_REQ_READ_REG     0x95
@@ -129,10 +131,10 @@ static int ch341_control_in(struct usb_device *dev,
 	return r;
 }
 
-static int ch341_set_baudrate(struct usb_device *dev,
-			      struct ch341_private *priv)
+static int ch341_init_set_baudrate(struct usb_device *dev,
+			      struct ch341_private *priv, unsigned ctrl)
 {
-	short a, b;
+	short a;
 	int r;
 	unsigned long factor;
 	short divisor;
@@ -152,11 +154,8 @@ static int ch341_set_baudrate(struct usb_device *dev,
 
 	factor = 0x10000 - factor;
 	a = (factor & 0xff00) | divisor;
-	b = factor & 0xff;
 
-	r = ch341_control_out(dev, 0x9a, 0x1312, a);
-	if (!r)
-		r = ch341_control_out(dev, 0x9a, 0x0f2c, b);
+	r = ch341_control_out(dev, CH341_SERIAL_INIT, 0x9c | (ctrl << 8), a | 0x80);
 
 	return r;
 }
@@ -177,7 +176,7 @@ static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 	if (!buffer)
 		return -ENOMEM;
 
-	r = ch341_control_in(dev, 0x95, 0x0706, 0, buffer, size);
+	r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x0706, 0, buffer, size);
 	if (r < 0)
 		goto out;
 
@@ -207,24 +206,20 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 		return -ENOMEM;
 
 	/* expect two bytes 0x27 0x00 */
-	r = ch341_control_in(dev, 0x5f, 0, 0, buffer, size);
+	r = ch341_control_in(dev, CH341_VERSION, 0, 0, buffer, size);
 	if (r < 0)
 		goto out;
 
-	r = ch341_control_out(dev, 0xa1, 0, 0);
-	if (r < 0)
-		goto out;
-
-	r = ch341_set_baudrate(dev, priv);
+	r = ch341_control_out(dev, CH341_SERIAL_INIT, 0, 0);
 	if (r < 0)
 		goto out;
 
 	/* expect two bytes 0x56 0x00 */
-	r = ch341_control_in(dev, 0x95, 0x2518, 0, buffer, size);
+	r = ch341_control_in(dev, CH341_REQ_READ_REG, 0x2518, 0, buffer, size);
 	if (r < 0)
 		goto out;
 
-	r = ch341_control_out(dev, 0x9a, 0x2518, 0x0050);
+	r = ch341_control_out(dev, CH341_REQ_WRITE_REG, 0x2518, 0x00c3);
 	if (r < 0)
 		goto out;
 
@@ -233,11 +228,7 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 	if (r < 0)
 		goto out;
 
-	r = ch341_control_out(dev, 0xa1, 0x501f, 0xd90a);
-	if (r < 0)
-		goto out;
-
-	r = ch341_set_baudrate(dev, priv);
+	r = ch341_init_set_baudrate(dev, priv, 0);
 	if (r < 0)
 		goto out;
 
@@ -352,16 +343,28 @@ static void ch341_set_termios(struct tty_struct *tty,
 	struct ch341_private *priv = usb_get_serial_port_data(port);
 	unsigned baud_rate;
 	unsigned long flags;
+	unsigned char ctrl;
+	int r;
+
+	/* redundant changes may cause the chip to lose bytes */
+	if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
+		return;
 
 	baud_rate = tty_get_baud_rate(tty);
 
 	priv->baud_rate = baud_rate;
 
+	ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
+
 	if (baud_rate) {
 		spin_lock_irqsave(&priv->lock, flags);
 		priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
 		spin_unlock_irqrestore(&priv->lock, flags);
-		ch341_set_baudrate(port->serial->dev, priv);
+		r = ch341_init_set_baudrate(port->serial->dev, priv, ctrl);
+		if (r < 0 && old_termios) {
+			priv->baud_rate = tty_termios_baud_rate(old_termios);
+			tty_termios_copy_hw(&tty->termios, old_termios);
+		}
 	} else {
 		spin_lock_irqsave(&priv->lock, flags);
 		priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
-- 
1.9.1

[PATCH v3 06/13] USB: ch341: add support for parity, frame length, stop bits

[Grigori Goronzy]

With the new reinitialization method, configuring parity, different
frame lengths and different stop bit settings work as expected on
both CH340G and CH341A.  This has been extensively tested with a
logic analyzer.

v2: only set mark/space when parity is enabled, simplifications,
patch termios HW flags.

Tested-by: Ryan Barber <rfb@skyscraper.nu>
Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
---
 drivers/usb/serial/ch341.c | 40 ++++++++++++++++++++++++++++++----------
 1 file changed, 30 insertions(+), 10 deletions(-)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 6181616..99b4621 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -341,7 +341,6 @@ static void ch341_set_termios(struct tty_struct *tty,
 		struct usb_serial_port *port, struct ktermios *old_termios)
 {
 	struct ch341_private *priv = usb_get_serial_port_data(port);
-	unsigned baud_rate;
 	unsigned long flags;
 	unsigned char ctrl;
 	int r;
@@ -350,13 +349,39 @@ static void ch341_set_termios(struct tty_struct *tty,
 	if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
 		return;
 
-	baud_rate = tty_get_baud_rate(tty);
+	priv->baud_rate = tty_get_baud_rate(tty);
 
-	priv->baud_rate = baud_rate;
+	ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
 
-	ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
+	switch (C_CSIZE(tty)) {
+	case CS5:
+		ctrl |= CH341_LCR_CS5;
+		break;
+	case CS6:
+		ctrl |= CH341_LCR_CS6;
+		break;
+	case CS7:
+		ctrl |= CH341_LCR_CS7;
+		break;
+	default:
+		tty->termios.c_cflag |= CS8;
+	case CS8:
+		ctrl |= CH341_LCR_CS8;
+		break;
+	}
+
+	if (C_PARENB(tty)) {
+		ctrl |= CH341_LCR_ENABLE_PAR;
+		if (C_PARODD(tty))
+			ctrl |= CH341_LCR_PAR_EVEN;
+		if (C_CMSPAR(tty))
+			ctrl |= CH341_LCR_MARK_SPACE;
+	}
+
+	if (C_CSTOPB(tty))
+		ctrl |= CH341_LCR_STOP_BITS_2;
 
-	if (baud_rate) {
+	if (priv->baud_rate) {
 		spin_lock_irqsave(&priv->lock, flags);
 		priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
 		spin_unlock_irqrestore(&priv->lock, flags);
@@ -373,11 +398,6 @@ static void ch341_set_termios(struct tty_struct *tty,
 
 	ch341_set_handshake(port->serial->dev, priv->line_control);
 
-	/* Unimplemented:
-	 * (cflag & CSIZE) : data bits [5, 8]
-	 * (cflag & PARENB) : parity {NONE, EVEN, ODD}
-	 * (cflag & CSTOPB) : stop bits [1, 2]
-	 */
 }
 
 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
-- 
1.9.1

Re: [PATCH v3 06/13] USB: ch341: add support for parity, frame length, stop bits

[Karl Palsson]

[-- Attachment #1.1: Type: text/plain, Size: 3196 bytes --]

Sorry if you get this twice, I was having some client problems,
but wanted to make sure you got this one...


Grigori Goronzy <greg@chown.ath.cx> wrote:
> With the new reinitialization method, configuring parity,
> different frame lengths and different stop bit settings work as
> expected on both CH340G and CH341A. This has been extensively
> tested with a logic analyzer.
> 
> v2: only set mark/space when parity is enabled,
> simplifications, patch termios HW flags.
> 
> Tested-by: Ryan Barber <rfb@skyscraper.nu>
> Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
> ---
>  drivers/usb/serial/ch341.c | 40 ++++++++++++++++++++++++++++++----------
>  1 file changed, 30 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/usb/serial/ch341.c
> b/drivers/usb/serial/ch341.c index 6181616..99b4621 100644
> --- a/drivers/usb/serial/ch341.c
> +++ b/drivers/usb/serial/ch341.c
> @@ -341,7 +341,6 @@ static void ch341_set_termios(struct tty_struct *tty,
>  		struct usb_serial_port *port, struct ktermios *old_termios)
>  {
>  	struct ch341_private *priv = usb_get_serial_port_data(port);
> -	unsigned baud_rate;
>  	unsigned long flags;
>  	unsigned char ctrl;
>  	int r;
> @@ -350,13 +349,39 @@ static void ch341_set_termios(struct tty_struct *tty,
>  	if (old_termios && !tty_termios_hw_change(&tty->termios, old_termios))
>  		return;
>  
> -	baud_rate = tty_get_baud_rate(tty);
> +	priv->baud_rate = tty_get_baud_rate(tty);
>  
> -	priv->baud_rate = baud_rate;
> +	ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
>  
> -	ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
> +	switch (C_CSIZE(tty)) {
> +	case CS5:
> +		ctrl |= CH341_LCR_CS5;
> +		break;
> +	case CS6:
> +		ctrl |= CH341_LCR_CS6;
> +		break;
> +	case CS7:
> +		ctrl |= CH341_LCR_CS7;
> +		break;
> +	default:
> +		tty->termios.c_cflag |= CS8;
> +	case CS8:
> +		ctrl |= CH341_LCR_CS8;
> +		break;
> +	}
> +
> +	if (C_PARENB(tty)) {
> +		ctrl |= CH341_LCR_ENABLE_PAR;
> +		if (C_PARODD(tty))
> +			ctrl |= CH341_LCR_PAR_EVEN;

Are you sure this does the right thing now? this is, as best as I
can tell, the inverse of what you had earlier, and doesn't read
right, if this is working, then I suggest renaming _LCR_PAR_EVEN
to LCR_PAR_ODD?

Cheers,
Karl P


> +		if (C_CMSPAR(tty))
> +			ctrl |= CH341_LCR_MARK_SPACE;
> +	}
> +
> +	if (C_CSTOPB(tty))
> +		ctrl |= CH341_LCR_STOP_BITS_2;
>  
> -	if (baud_rate) {
> +	if (priv->baud_rate) {
>  		spin_lock_irqsave(&priv->lock, flags);
>  		priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
>  		spin_unlock_irqrestore(&priv->lock, flags);
> @@ -373,11 +398,6 @@ static void ch341_set_termios(struct tty_struct *tty,
>  
>  	ch341_set_handshake(port->serial->dev, priv->line_control);
>  
> -	/* Unimplemented:
> -	 * (cflag & CSIZE) : data bits [5, 8]
> -	 * (cflag & PARENB) : parity {NONE, EVEN, ODD}
> -	 * (cflag & CSTOPB) : stop bits [1, 2]
> -	 */
>  }
>  
>  static void ch341_break_ctl(struct tty_struct *tty, int break_state)
> -- 
> 1.9.1
> 
> --
> To unsubscribe from this list: send the line "unsubscribe
> linux-usb" in the body of a message to
> majordomo@vger.kernel.org More majordomo info at
> http://vger.kernel.org/majordomo-info.html

[-- Attachment #2: OpenPGP Digital Signature --]
[-- Type: application/pgp-signature, Size: 819 bytes --]

Re: [PATCH v3 06/13] USB: ch341: add support for parity, frame length, stop bits

[Grigori Goronzy]

On 2016-04-11 19:25, Karl Palsson wrote:
> Sorry if you get this twice, I was having some client problems,
> but wanted to make sure you got this one...
> 
> 
> Grigori Goronzy <greg@chown.ath.cx> wrote:
>> With the new reinitialization method, configuring parity,
>> different frame lengths and different stop bit settings work as
>> expected on both CH340G and CH341A. This has been extensively
>> tested with a logic analyzer.
>> 
>> v2: only set mark/space when parity is enabled,
>> simplifications, patch termios HW flags.
>> 
>> Tested-by: Ryan Barber <rfb@skyscraper.nu>
>> Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
>> ---
>>  drivers/usb/serial/ch341.c | 40 
>> ++++++++++++++++++++++++++++++----------
>>  1 file changed, 30 insertions(+), 10 deletions(-)
>> 
>> diff --git a/drivers/usb/serial/ch341.c
>> b/drivers/usb/serial/ch341.c index 6181616..99b4621 100644
>> --- a/drivers/usb/serial/ch341.c
>> +++ b/drivers/usb/serial/ch341.c
>> @@ -341,7 +341,6 @@ static void ch341_set_termios(struct tty_struct 
>> *tty,
>>  		struct usb_serial_port *port, struct ktermios *old_termios)
>>  {
>>  	struct ch341_private *priv = usb_get_serial_port_data(port);
>> -	unsigned baud_rate;
>>  	unsigned long flags;
>>  	unsigned char ctrl;
>>  	int r;
>> @@ -350,13 +349,39 @@ static void ch341_set_termios(struct tty_struct 
>> *tty,
>>  	if (old_termios && !tty_termios_hw_change(&tty->termios, 
>> old_termios))
>>  		return;
>> 
>> -	baud_rate = tty_get_baud_rate(tty);
>> +	priv->baud_rate = tty_get_baud_rate(tty);
>> 
>> -	priv->baud_rate = baud_rate;
>> +	ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX;
>> 
>> -	ctrl = CH341_LCR_ENABLE_RX | CH341_LCR_ENABLE_TX | CH341_LCR_CS8;
>> +	switch (C_CSIZE(tty)) {
>> +	case CS5:
>> +		ctrl |= CH341_LCR_CS5;
>> +		break;
>> +	case CS6:
>> +		ctrl |= CH341_LCR_CS6;
>> +		break;
>> +	case CS7:
>> +		ctrl |= CH341_LCR_CS7;
>> +		break;
>> +	default:
>> +		tty->termios.c_cflag |= CS8;
>> +	case CS8:
>> +		ctrl |= CH341_LCR_CS8;
>> +		break;
>> +	}
>> +
>> +	if (C_PARENB(tty)) {
>> +		ctrl |= CH341_LCR_ENABLE_PAR;
>> +		if (C_PARODD(tty))
>> +			ctrl |= CH341_LCR_PAR_EVEN;
> 
> Are you sure this does the right thing now? this is, as best as I
> can tell, the inverse of what you had earlier, and doesn't read
> right, if this is working, then I suggest renaming _LCR_PAR_EVEN
> to LCR_PAR_ODD?
> 

No, this is absolutely wrong, of course.  I only did some sporadic 
testing because my refactoring wasn't supposed to change functionality.  
Thanks for pointing it out!

Grigori

[PATCH v3 07/13] USB: ch341: add debug output for chip version

[Grigori Goronzy]

There are at least two hardware revisions, this may be helpful in
case compatibility issues need to be debugged.

Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
---
 drivers/usb/serial/ch341.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 99b4621..94e6016 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -209,6 +209,7 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 	r = ch341_control_in(dev, CH341_VERSION, 0, 0, buffer, size);
 	if (r < 0)
 		goto out;
+	dev_dbg(&dev->dev, "Chip version: %d\n", buffer[0]);
 
 	r = ch341_control_out(dev, CH341_SERIAL_INIT, 0, 0);
 	if (r < 0)
-- 
1.9.1

[PATCH v3 08/13] USB: ch341: add support for RTS/CTS flow control

[Grigori Goronzy]

v2: use correct flag variable.

Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
---
 drivers/usb/serial/ch341.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 94e6016..135370b 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -68,6 +68,7 @@
 #define CH341_REQ_READ_REG     0x95
 #define CH341_REG_BREAK1       0x05
 #define CH341_REG_LCR          0x18
+#define CH341_REG_RTSCTS       0x27
 #define CH341_NBREAK_BITS_REG1 0x01
 
 #define CH341_LCR_ENABLE_RX    0x80
@@ -399,6 +400,16 @@ static void ch341_set_termios(struct tty_struct *tty,
 
 	ch341_set_handshake(port->serial->dev, priv->line_control);
 
+	if (cflag & CRTSCTS) {
+		r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
+				CH341_REG_RTSCTS | ((uint16_t)CH341_REG_RTSCTS << 8),
+				0x0101);
+		if (r < 0) {
+			dev_err(&port->dev, "%s - USB control write error (%d)\n",
+					__func__, r);
+			tty->termios.c_cflag &= ~CRTSCTS;
+		}
+	}
 }
 
 static void ch341_break_ctl(struct tty_struct *tty, int break_state)
-- 
1.9.1

Re: [PATCH v3 08/13] USB: ch341: add support for RTS/CTS flow control

[kbuild test robot]

[-- Attachment #1: Type: text/plain, Size: 1654 bytes --]

Hi Grigori,

[auto build test ERROR on v4.5-rc7]
[cannot apply to usb/usb-testing usb-serial/usb-next v4.6-rc2 v4.6-rc1 next-20160408]
[if your patch is applied to the wrong git tree, please drop us a note to help improving the system]

url:    https://github.com/0day-ci/linux/commits/Grigori-Goronzy/USB-ch341-fix-error-handling-on-resume/20160411-075235
config: x86_64-allmodconfig (attached as .config)
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

Note: the linux-review/Grigori-Goronzy/USB-ch341-fix-error-handling-on-resume/20160411-075235 HEAD a1faa3e66e1410087d7b4711181282df9b094024 builds fine.
      It only hurts bisectibility.

All errors (new ones prefixed by >>):

   drivers/usb/serial/ch341.c: In function 'ch341_set_termios':
>> drivers/usb/serial/ch341.c:403:6: error: 'cflag' undeclared (first use in this function)
     if (cflag & CRTSCTS) {
         ^
   drivers/usb/serial/ch341.c:403:6: note: each undeclared identifier is reported only once for each function it appears in

vim +/cflag +403 drivers/usb/serial/ch341.c

   397			priv->line_control &= ~(CH341_BIT_DTR | CH341_BIT_RTS);
   398			spin_unlock_irqrestore(&priv->lock, flags);
   399		}
   400	
   401		ch341_set_handshake(port->serial->dev, priv->line_control);
   402	
 > 403		if (cflag & CRTSCTS) {
   404			r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
   405					CH341_REG_RTSCTS | ((uint16_t)CH341_REG_RTSCTS << 8),
   406					0x0101);

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

[-- Attachment #2: .config.gz --]
[-- Type: application/octet-stream, Size: 53124 bytes --]

[PATCH v3 09/13] USB: ch341: fix coding style

[Grigori Goronzy]

No functional change.  The following adjustments were made to be more in
line with official coding style and to be more consistent.

Stop mixing tabs and spaces for alignment.  Stop putting labels and
statements into the same line.  Use braces consistently for a single
statement.

v2: drop most changes, particularly indentation changes.

Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
---
 drivers/usb/serial/ch341.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 135370b..2d28556 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -133,7 +133,7 @@ static int ch341_control_in(struct usb_device *dev,
 }
 
 static int ch341_init_set_baudrate(struct usb_device *dev,
-			      struct ch341_private *priv, unsigned ctrl)
+				   struct ch341_private *priv, unsigned ctrl)
 {
 	short a;
 	int r;
@@ -187,10 +187,12 @@ static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 		spin_lock_irqsave(&priv->lock, flags);
 		priv->line_status = (~(*buffer)) & CH341_BITS_MODEM_STAT;
 		spin_unlock_irqrestore(&priv->lock, flags);
-	} else
+	} else {
 		r = -EPROTO;
+	}
 
-out:	kfree(buffer);
+out:
+	kfree(buffer);
 	return r;
 }
 
@@ -241,7 +243,8 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 	/* expect 0x9f 0xee */
 	r = ch341_get_status(dev, priv);
 
-out:	kfree(buffer);
+out:
+	kfree(buffer);
 	return r;
 }
 
@@ -265,7 +268,8 @@ static int ch341_port_probe(struct usb_serial_port *port)
 	usb_set_serial_port_data(port, priv);
 	return 0;
 
-error:	kfree(priv);
+error:
+	kfree(priv);
 	return r;
 }
 
@@ -479,7 +483,7 @@ static int ch341_tiocmset(struct tty_struct *tty,
 }
 
 static void ch341_update_line_status(struct usb_serial_port *port,
-					unsigned char *data, size_t len)
+				     unsigned char *data, size_t len)
 {
 	struct ch341_private *priv = usb_get_serial_port_data(port);
 	struct tty_struct *tty;
@@ -600,7 +604,7 @@ static struct usb_serial_driver ch341_device = {
 	.id_table          = id_table,
 	.num_ports         = 1,
 	.open              = ch341_open,
-	.dtr_rts	   = ch341_dtr_rts,
+	.dtr_rts           = ch341_dtr_rts,
 	.carrier_raised	   = ch341_carrier_raised,
 	.close             = ch341_close,
 	.set_termios       = ch341_set_termios,
-- 
1.9.1

[PATCH v3 10/13] USB: ch341: clean up messages

[Grigori Goronzy]

No functional change.  Remove explicit function name printing, it's
easy to use dynamic debug to print it every time, if required.
Fix capitalization and phrasing in some cases.  Drop useless
information like a USB buffer pointer, which is not helpful.

Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
---
 drivers/usb/serial/ch341.c | 48 +++++++++++++++++++++-------------------------
 1 file changed, 22 insertions(+), 26 deletions(-)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 2d28556..bf256eb 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -106,7 +106,7 @@ static int ch341_control_out(struct usb_device *dev, u8 request,
 {
 	int r;
 
-	dev_dbg(&dev->dev, "ch341_control_out(%02x,%02x,%04x,%04x)\n",
+	dev_dbg(&dev->dev, "control_out(%02x,%02x,%04x,%04x)\n",
 		USB_DIR_OUT|0x40, (int)request, (int)value, (int)index);
 
 	r = usb_control_msg(dev, usb_sndctrlpipe(dev, 0), request,
@@ -122,8 +122,8 @@ static int ch341_control_in(struct usb_device *dev,
 {
 	int r;
 
-	dev_dbg(&dev->dev, "ch341_control_in(%02x,%02x,%04x,%04x,%p,%u)\n",
-		USB_DIR_IN|0x40, (int)request, (int)value, (int)index, buf,
+	dev_dbg(&dev->dev, "control_in(%02x,%02x,%04x,%04x,%u)\n",
+		USB_DIR_IN|0x40, (int)request, (int)value, (int)index,
 		(int)bufsize);
 
 	r = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0), request,
@@ -327,11 +327,11 @@ static int ch341_open(struct tty_struct *tty, struct usb_serial_port *port)
 	if (tty)
 		ch341_set_termios(tty, port, NULL);
 
-	dev_dbg(&port->dev, "%s - submitting interrupt urb\n", __func__);
+	dev_dbg(&port->dev, "Submitting interrupt URB\n");
 	r = usb_submit_urb(port->interrupt_in_urb, GFP_KERNEL);
 	if (r) {
-		dev_err(&port->dev, "%s - failed to submit interrupt urb: %d\n",
-			__func__, r);
+		dev_err(&port->dev,
+			"Failed to submit interrupt URB: %d\n", r);
 		goto out;
 	}
 
@@ -409,8 +409,7 @@ static void ch341_set_termios(struct tty_struct *tty,
 				CH341_REG_RTSCTS | ((uint16_t)CH341_REG_RTSCTS << 8),
 				0x0101);
 		if (r < 0) {
-			dev_err(&port->dev, "%s - USB control write error (%d)\n",
-					__func__, r);
+			dev_err(&port->dev, "USB control write error: %d\n", r);
 			tty->termios.c_cflag &= ~CRTSCTS;
 		}
 	}
@@ -432,29 +431,27 @@ static void ch341_break_ctl(struct tty_struct *tty, int break_state)
 	r = ch341_control_in(port->serial->dev, CH341_REQ_READ_REG,
 			ch341_break_reg, 0, break_reg, 2);
 	if (r < 0) {
-		dev_err(&port->dev, "%s - USB control read error (%d)\n",
-				__func__, r);
+		dev_err(&port->dev, "USB control read error: %d\n", r);
 		goto out;
 	}
-	dev_dbg(&port->dev, "%s - initial ch341 break register contents - reg1: %x, reg2: %x\n",
-		__func__, break_reg[0], break_reg[1]);
+	dev_dbg(&port->dev, "Initial break register contents - reg1: %x, reg2: %x\n",
+		break_reg[0], break_reg[1]);
 	if (break_state != 0) {
-		dev_dbg(&port->dev, "%s - Enter break state requested\n", __func__);
+		dev_dbg(&port->dev, "Enter break state requested\n");
 		break_reg[0] &= ~CH341_NBREAK_BITS_REG1;
 		break_reg[1] &= ~CH341_LCR_ENABLE_TX;
 	} else {
-		dev_dbg(&port->dev, "%s - Leave break state requested\n", __func__);
+		dev_dbg(&port->dev, "Leave break state requested\n");
 		break_reg[0] |= CH341_NBREAK_BITS_REG1;
 		break_reg[1] |= CH341_LCR_ENABLE_TX;
 	}
-	dev_dbg(&port->dev, "%s - New ch341 break register contents - reg1: %x, reg2: %x\n",
-		__func__, break_reg[0], break_reg[1]);
+	dev_dbg(&port->dev, "New break register contents - reg1: %x, reg2: %x\n",
+		break_reg[0], break_reg[1]);
 	reg_contents = get_unaligned_le16(break_reg);
 	r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
 			ch341_break_reg, reg_contents);
 	if (r < 0)
-		dev_err(&port->dev, "%s - USB control write error (%d)\n",
-				__func__, r);
+		dev_err(&port->dev, "USB control write error: %d\n", r);
 out:
 	kfree(break_reg);
 }
@@ -502,7 +499,7 @@ static void ch341_update_line_status(struct usb_serial_port *port,
 	spin_unlock_irqrestore(&priv->lock, flags);
 
 	if (data[1] & CH341_MULT_STAT)
-		dev_dbg(&port->dev, "%s - multiple status change\n", __func__);
+		dev_dbg(&port->dev, "Multiple status change\n");
 
 	if (!delta)
 		return;
@@ -541,12 +538,12 @@ static void ch341_read_int_callback(struct urb *urb)
 	case -ENOENT:
 	case -ESHUTDOWN:
 		/* this urb is terminated, clean up */
-		dev_dbg(&urb->dev->dev, "%s - urb shutting down: %d\n",
-			__func__, urb->status);
+		dev_dbg(&urb->dev->dev, "URB shutting down: %d\n",
+			urb->status);
 		return;
 	default:
-		dev_dbg(&urb->dev->dev, "%s - nonzero urb status: %d\n",
-			__func__, urb->status);
+		dev_dbg(&urb->dev->dev, "Nonzero URB status: %d\n",
+			urb->status);
 		goto exit;
 	}
 
@@ -555,8 +552,7 @@ static void ch341_read_int_callback(struct urb *urb)
 exit:
 	status = usb_submit_urb(urb, GFP_ATOMIC);
 	if (status) {
-		dev_err(&urb->dev->dev, "%s - usb_submit_urb failed: %d\n",
-			__func__, status);
+		dev_err(&urb->dev->dev, "URB submit failed: %d\n", status);
 	}
 }
 
@@ -581,7 +577,7 @@ static int ch341_tiocmget(struct tty_struct *tty)
 		  | ((status & CH341_BIT_RI)	? TIOCM_RI  : 0)
 		  | ((status & CH341_BIT_DCD)	? TIOCM_CD  : 0);
 
-	dev_dbg(&port->dev, "%s - result = %x\n", __func__, result);
+	dev_dbg(&port->dev, "Result = %x\n", result);
 
 	return result;
 }
-- 
1.9.1

[PATCH v3 11/13] USB: ch341: improve B0 handling

[Grigori Goronzy]

Check for B0 in a more idiomatic way and make sure to not enable
RTS/CTS hardware flow control in B0 as it may override the control
lines.  Also make sure to only enable RTS/DTR if there's a transition
from B0.

v2: use c_cflag macros.

Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
---
 drivers/usb/serial/ch341.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index bf256eb..78590b7 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -387,10 +387,12 @@ static void ch341_set_termios(struct tty_struct *tty,
 	if (C_CSTOPB(tty))
 		ctrl |= CH341_LCR_STOP_BITS_2;
 
-	if (priv->baud_rate) {
-		spin_lock_irqsave(&priv->lock, flags);
-		priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
-		spin_unlock_irqrestore(&priv->lock, flags);
+	if (C_BAUD(tty) != B0) {
+		if (old_termios && (old_termios->c_cflag & CBAUD) == B0) {
+			spin_lock_irqsave(&priv->lock, flags);
+			priv->line_control |= (CH341_BIT_DTR | CH341_BIT_RTS);
+			spin_unlock_irqrestore(&priv->lock, flags);
+		}
 		r = ch341_init_set_baudrate(port->serial->dev, priv, ctrl);
 		if (r < 0 && old_termios) {
 			priv->baud_rate = tty_termios_baud_rate(old_termios);
@@ -404,7 +406,7 @@ static void ch341_set_termios(struct tty_struct *tty,
 
 	ch341_set_handshake(port->serial->dev, priv->line_control);
 
-	if (cflag & CRTSCTS) {
+	if (C_CRTSCTS(tty) && C_BAUD(tty) != B0) {
 		r = ch341_control_out(port->serial->dev, CH341_REQ_WRITE_REG,
 				CH341_REG_RTSCTS | ((uint16_t)CH341_REG_RTSCTS << 8),
 				0x0101);
-- 
1.9.1

[PATCH v3 12/13] USB: ch341: get rid of default configuration

[Grigori Goronzy]

If the serial port hasn't been opened yet, no baud rate should be
set and RTS/DTR need to be deasserted.

Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
---
 drivers/usb/serial/ch341.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 78590b7..451fa64 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -24,7 +24,6 @@
 #include <linux/serial.h>
 #include <asm/unaligned.h>
 
-#define DEFAULT_BAUD_RATE 9600
 #define DEFAULT_TIMEOUT   1000
 
 /* flags for IO-Bits */
@@ -232,10 +231,6 @@ static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
 	if (r < 0)
 		goto out;
 
-	r = ch341_init_set_baudrate(dev, priv, 0);
-	if (r < 0)
-		goto out;
-
 	r = ch341_set_handshake(dev, priv->line_control);
 	if (r < 0)
 		goto out;
@@ -258,8 +253,6 @@ static int ch341_port_probe(struct usb_serial_port *port)
 		return -ENOMEM;
 
 	spin_lock_init(&priv->lock);
-	priv->baud_rate = DEFAULT_BAUD_RATE;
-	priv->line_control = CH341_BIT_RTS | CH341_BIT_DTR;
 
 	r = ch341_configure(port->serial->dev, priv);
 	if (r < 0)
-- 
1.9.1

[PATCH v3 13/13] USB: ch341: implement tx_empty callback

[Grigori Goronzy]

The status bit was found with USB captures of the Windows driver and
some luck.  Tested on CH340G and CH341A.

v2: unify general status definitions

Signed-off-by: Grigori Goronzy <greg@chown.ath.cx>
---
 drivers/usb/serial/ch341.c | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/serial/ch341.c b/drivers/usb/serial/ch341.c
index 451fa64..000d391 100644
--- a/drivers/usb/serial/ch341.c
+++ b/drivers/usb/serial/ch341.c
@@ -39,9 +39,6 @@
 /* third irq byte base 0x94 + below */
 /* fourth irq byte normally 0xee */
 
-/* second interrupt byte */
-#define CH341_MULT_STAT 0x04 /* multiple status since last interrupt event */
-
 /* status returned in third interrupt answer byte, inverted in data
    from irq */
 #define CH341_BIT_CTS 0x01
@@ -81,6 +78,10 @@
 #define CH341_LCR_CS6          0x01
 #define CH341_LCR_CS5          0x00
 
+/* General status from register 0x07 and second interrupt byte */
+#define CH341_STATUS_TXBUSY    0x01
+#define CH341_STATUS_MULTI     0x04
+
 static const struct usb_device_id id_table[] = {
 	{ USB_DEVICE(0x4348, 0x5523) },
 	{ USB_DEVICE(0x1a86, 0x7523) },
@@ -94,6 +95,7 @@ struct ch341_private {
 	unsigned baud_rate; /* set baud rate */
 	u8 line_control; /* set line control value RTS/DTR */
 	u8 line_status; /* active status of modem control inputs */
+	u8 uart_status; /* generic UART status bits */
 };
 
 static void ch341_set_termios(struct tty_struct *tty,
@@ -184,7 +186,8 @@ static int ch341_get_status(struct usb_device *dev, struct ch341_private *priv)
 	if (r == 2) {
 		r = 0;
 		spin_lock_irqsave(&priv->lock, flags);
-		priv->line_status = (~(*buffer)) & CH341_BITS_MODEM_STAT;
+		priv->line_status = (~buffer[0]) & CH341_BITS_MODEM_STAT;
+		priv->uart_status = buffer[1];
 		spin_unlock_irqrestore(&priv->lock, flags);
 	} else {
 		r = -EPROTO;
@@ -195,6 +198,18 @@ out:
 	return r;
 }
 
+static bool ch341_tx_empty(struct usb_serial_port *port)
+{
+	int r;
+	struct ch341_private *priv = usb_get_serial_port_data(port);
+
+	r = ch341_get_status(port->serial->dev, priv);
+	if (r < 0)
+		return true;
+
+	return !(priv->uart_status & CH341_STATUS_TXBUSY);
+}
+
 /* -------------------------------------------------------------------------- */
 
 static int ch341_configure(struct usb_device *dev, struct ch341_private *priv)
@@ -493,7 +508,7 @@ static void ch341_update_line_status(struct usb_serial_port *port,
 	priv->line_status = status;
 	spin_unlock_irqrestore(&priv->lock, flags);
 
-	if (data[1] & CH341_MULT_STAT)
+	if (data[1] & CH341_STATUS_MULTI)
 		dev_dbg(&port->dev, "Multiple status change\n");
 
 	if (!delta)
@@ -599,6 +614,7 @@ static struct usb_serial_driver ch341_device = {
 	.carrier_raised	   = ch341_carrier_raised,
 	.close             = ch341_close,
 	.set_termios       = ch341_set_termios,
+	.tx_empty          = ch341_tx_empty,
 	.break_ctl         = ch341_break_ctl,
 	.tiocmget          = ch341_tiocmget,
 	.tiocmset          = ch341_tiocmset,
-- 
1.9.1