diff mbox series

[v2,7/7] USB: serial: ftdi_sio: Fill c_*speed fields with real baud rate

Message ID 20220712115306.26471-8-kabel@kernel.org
State New
Headers show
Series ftdi_sio driver improvements | expand

Commit Message

Marek Behún July 12, 2022, 11:53 a.m. UTC 
From: Pali Rohár <pali@kernel.org>

Calculate baud rate value in c_*speed fields to the real values which were
set on hardware. For this operation, add a new set of methods
*_divisor_to_baud() for each chip and use them for calculating the real
baud rate values.

Each *_divisor_to_baud() method is constructed as an inverse function of
its corresponding *_baud_to_divisor() method.

Signed-off-by: Pali Rohár <pali@kernel.org>
Tested-by: Marek Behún <kabel@kernel.org>
Signed-off-by: Marek Behún <kabel@kernel.org>
---
 drivers/usb/serial/ftdi_sio.c | 83 +++++++++++++++++++++++++++++++++++
 1 file changed, 83 insertions(+)

Comments

Johan Hovold July 24, 2022, 12:41 p.m. UTC | #1 
On Tue, Jul 12, 2022 at 01:53:06PM +0200, Marek Behún wrote:
> From: Pali Rohár <pali@kernel.org>
> 
> Calculate baud rate value in c_*speed fields to the real values which were
> set on hardware. For this operation, add a new set of methods
> *_divisor_to_baud() for each chip and use them for calculating the real
> baud rate values.
> 
> Each *_divisor_to_baud() method is constructed as an inverse function of
> its corresponding *_baud_to_divisor() method.
> 
> Signed-off-by: Pali Rohár <pali@kernel.org>
> Tested-by: Marek Behún <kabel@kernel.org>
> Signed-off-by: Marek Behún <kabel@kernel.org>
> ---
>  drivers/usb/serial/ftdi_sio.c | 83 +++++++++++++++++++++++++++++++++++
>  1 file changed, 83 insertions(+)
> 
> diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
> index 39e8c5d06157..838acce53e69 100644
> --- a/drivers/usb/serial/ftdi_sio.c
> +++ b/drivers/usb/serial/ftdi_sio.c
> @@ -1167,6 +1167,23 @@ static int ftdi_sio_baud_to_divisor(int baud)
>  	}
>  }
>  
> +static int ftdi_sdio_divisor_to_baud(u32 divisor)
> +{
> +	switch (divisor) {
> +	case ftdi_sio_b300: return 300;
> +	case ftdi_sio_b600: return 600;
> +	case ftdi_sio_b1200: return 1200;
> +	case ftdi_sio_b2400: return 2400;
> +	case ftdi_sio_b4800: return 4800;
> +	case ftdi_sio_b9600: return 9600;
> +	case ftdi_sio_b19200: return 19200;
> +	case ftdi_sio_b38400: return 38400;
> +	case ftdi_sio_b57600: return 57600;
> +	case ftdi_sio_b115200: return 115200;
> +	default: return 9600;
> +	}
> +}

This one should not be needed as sio only supports this discrete set of
values in the first place.

>  static unsigned short int ftdi_232am_baud_base_to_divisor(int baud, int base)
>  {
>  	unsigned short int divisor;
> @@ -1189,15 +1206,33 @@ static unsigned short int ftdi_232am_baud_base_to_divisor(int baud, int base)
>  	return divisor;
>  }
>  
> +static int ftdi_232am_divisor_base_to_baud(unsigned short int divisor, int base)

I believe "base" was used as a function name suffix in the inverse
function (due to the additional base argument).

> +{
> +	static const unsigned char divfrac_inv[4] = { 0, 4, 2, 1 };
> +	unsigned int divisor3;
> +
> +	if (divisor == 0)
> +		divisor = 1;
> +	divisor3 = (GENMASK(13, 0) & divisor) << 3;
> +	divisor3 |= divfrac_inv[(divisor >> 14) & 0x3];
> +	return DIV_ROUND_CLOSEST(base, 2 * divisor3);
> +}

I don't have the motivation to try to review these inverses right now.

Let's get the rest of the series in order first.

Johan
Johan Hovold Sept. 13, 2022, 3:02 p.m. UTC | #2 
On Thu, Aug 18, 2022 at 04:17:38PM +0200, Pali Rohár wrote:
> On Sunday 24 July 2022 14:41:19 Johan Hovold wrote:
> > On Tue, Jul 12, 2022 at 01:53:06PM +0200, Marek Behún wrote:
> > > From: Pali Rohár <pali@kernel.org>
> > > 
> > > Calculate baud rate value in c_*speed fields to the real values which were
> > > set on hardware. For this operation, add a new set of methods
> > > *_divisor_to_baud() for each chip and use them for calculating the real
> > > baud rate values.
> > > 
> > > Each *_divisor_to_baud() method is constructed as an inverse function of
> > > its corresponding *_baud_to_divisor() method.
> > > 
> > > Signed-off-by: Pali Rohár <pali@kernel.org>
> > > Tested-by: Marek Behún <kabel@kernel.org>
> > > Signed-off-by: Marek Behún <kabel@kernel.org>
> > > ---
> > >  drivers/usb/serial/ftdi_sio.c | 83 +++++++++++++++++++++++++++++++++++
> > >  1 file changed, 83 insertions(+)

> > >  static unsigned short int ftdi_232am_baud_base_to_divisor(int baud, int base)
> > >  {
> > >  	unsigned short int divisor;
> > > @@ -1189,15 +1206,33 @@ static unsigned short int ftdi_232am_baud_base_to_divisor(int baud, int base)
> > >  	return divisor;
> > >  }
> > >  
> > > +static int ftdi_232am_divisor_base_to_baud(unsigned short int divisor, int base)
> > 
> > I believe "base" was used as a function name suffix in the inverse
> > function (due to the additional base argument).
> 
> Yes, in the same way as it used in name of ftdi_232am_baud_base_to_divisor.

No, you used "base" as an infix here.

Johan
Pali Rohár Sept. 13, 2022, 3:24 p.m. UTC | #3 
On Tuesday 13 September 2022 17:02:39 Johan Hovold wrote:
> On Thu, Aug 18, 2022 at 04:17:38PM +0200, Pali Rohár wrote:
> > On Sunday 24 July 2022 14:41:19 Johan Hovold wrote:
> > > On Tue, Jul 12, 2022 at 01:53:06PM +0200, Marek Behún wrote:
> > > > From: Pali Rohár <pali@kernel.org>
> > > > 
> > > > Calculate baud rate value in c_*speed fields to the real values which were
> > > > set on hardware. For this operation, add a new set of methods
> > > > *_divisor_to_baud() for each chip and use them for calculating the real
> > > > baud rate values.
> > > > 
> > > > Each *_divisor_to_baud() method is constructed as an inverse function of
> > > > its corresponding *_baud_to_divisor() method.
> > > > 
> > > > Signed-off-by: Pali Rohár <pali@kernel.org>
> > > > Tested-by: Marek Behún <kabel@kernel.org>
> > > > Signed-off-by: Marek Behún <kabel@kernel.org>
> > > > ---
> > > >  drivers/usb/serial/ftdi_sio.c | 83 +++++++++++++++++++++++++++++++++++
> > > >  1 file changed, 83 insertions(+)
> 
> > > >  static unsigned short int ftdi_232am_baud_base_to_divisor(int baud, int base)
> > > >  {
> > > >  	unsigned short int divisor;
> > > > @@ -1189,15 +1206,33 @@ static unsigned short int ftdi_232am_baud_base_to_divisor(int baud, int base)
> > > >  	return divisor;
> > > >  }
> > > >  
> > > > +static int ftdi_232am_divisor_base_to_baud(unsigned short int divisor, int base)
> > > 
> > > I believe "base" was used as a function name suffix in the inverse
> > > function (due to the additional base argument).
> > 
> > Yes, in the same way as it used in name of ftdi_232am_baud_base_to_divisor.
> 
> No, you used "base" as an infix here.
> 
> Johan

Yes, of course, it is "in the middle" because I said I used it in the
same way as in ftdi_232am_baud_base_to_divisor.

ftdi_232am_baud_base_to_divisor converts input "baud" and input "base"
to return "divisor". Hence baud_base_to_divisor.

And so ftdi_232am_divisor_base_to_baud converts input "divisor" and
input "base" to return value "baud". Hence divisor_base_to_baud.

So what is the problem? I still have not caught.
Johan Hovold Sept. 13, 2022, 3:34 p.m. UTC | #4 
On Tue, Sep 13, 2022 at 05:24:05PM +0200, Pali Rohár wrote:
> On Tuesday 13 September 2022 17:02:39 Johan Hovold wrote:
> > On Thu, Aug 18, 2022 at 04:17:38PM +0200, Pali Rohár wrote:
> > > On Sunday 24 July 2022 14:41:19 Johan Hovold wrote:

> > > > >  static unsigned short int ftdi_232am_baud_base_to_divisor(int baud, int base)
> > > > >  {
> > > > >  	unsigned short int divisor;
> > > > > @@ -1189,15 +1206,33 @@ static unsigned short int ftdi_232am_baud_base_to_divisor(int baud, int base)
> > > > >  	return divisor;
> > > > >  }
> > > > >  
> > > > > +static int ftdi_232am_divisor_base_to_baud(unsigned short int divisor, int base)
> > > > 
> > > > I believe "base" was used as a function name suffix in the inverse
> > > > function (due to the additional base argument).
> > > 
> > > Yes, in the same way as it used in name of ftdi_232am_baud_base_to_divisor.
> > 
> > No, you used "base" as an infix here.

> Yes, of course, it is "in the middle" because I said I used it in the
> same way as in ftdi_232am_baud_base_to_divisor.
> 
> ftdi_232am_baud_base_to_divisor converts input "baud" and input "base"
> to return "divisor". Hence baud_base_to_divisor.
> 
> And so ftdi_232am_divisor_base_to_baud converts input "divisor" and
> input "base" to return value "baud". Hence divisor_base_to_baud.
> 
> So what is the problem? I still have not caught.

Ok, I should have looked closer at the code before replying.

I believe I expected "base" to be used as a suffix in the current code
but that doesn't appear to be the case. So you're just following the
current style.

Johan
diff mbox series

Patch

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 39e8c5d06157..838acce53e69 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1167,6 +1167,23 @@  static int ftdi_sio_baud_to_divisor(int baud)
 	}
 }
 
+static int ftdi_sdio_divisor_to_baud(u32 divisor)
+{
+	switch (divisor) {
+	case ftdi_sio_b300: return 300;
+	case ftdi_sio_b600: return 600;
+	case ftdi_sio_b1200: return 1200;
+	case ftdi_sio_b2400: return 2400;
+	case ftdi_sio_b4800: return 4800;
+	case ftdi_sio_b9600: return 9600;
+	case ftdi_sio_b19200: return 19200;
+	case ftdi_sio_b38400: return 38400;
+	case ftdi_sio_b57600: return 57600;
+	case ftdi_sio_b115200: return 115200;
+	default: return 9600;
+	}
+}
+
 static unsigned short int ftdi_232am_baud_base_to_divisor(int baud, int base)
 {
 	unsigned short int divisor;
@@ -1189,15 +1206,33 @@  static unsigned short int ftdi_232am_baud_base_to_divisor(int baud, int base)
 	return divisor;
 }
 
+static int ftdi_232am_divisor_base_to_baud(unsigned short int divisor, int base)
+{
+	static const unsigned char divfrac_inv[4] = { 0, 4, 2, 1 };
+	unsigned int divisor3;
+
+	if (divisor == 0)
+		divisor = 1;
+	divisor3 = (GENMASK(13, 0) & divisor) << 3;
+	divisor3 |= divfrac_inv[(divisor >> 14) & 0x3];
+	return DIV_ROUND_CLOSEST(base, 2 * divisor3);
+}
+
 static unsigned short int ftdi_232am_baud_to_divisor(int baud)
 {
 	 return ftdi_232am_baud_base_to_divisor(baud, 48000000);
 }
 
+static int ftdi_232am_divisor_to_baud(unsigned short int divisor)
+{
+	return ftdi_232am_divisor_base_to_baud(divisor, 48000000);
+}
+
 static u32 ftdi_232bm_baud_base_to_divisor(int baud, int base)
 {
 	static const unsigned char divfrac[8] = { 0, 3, 2, 4, 1, 5, 6, 7 };
 	u32 divisor;
+
 	/* divisor shifted 3 bits to the left */
 	int divisor3 = DIV_ROUND_CLOSEST(base, 2 * baud);
 	if (divisor3 > GENMASK(16, 0))
@@ -1212,11 +1247,31 @@  static u32 ftdi_232bm_baud_base_to_divisor(int baud, int base)
 	return divisor;
 }
 
+static int ftdi_232bm_divisor_base_to_baud(u32 divisor, int base)
+{
+	static const unsigned char divfrac_inv[8] = { 0, 4, 2, 1, 3, 5, 6, 7 };
+	u32 divisor3;
+
+	/* Deal with special cases for highest baud rates. */
+	if (divisor == 0)
+		divisor = 1;		/* 1.0 */
+	else if (divisor == 1)
+		divisor = 0x4001;	/* 1.5 */
+	divisor3 = (GENMASK(13, 0) & divisor) << 3;
+	divisor3 |= divfrac_inv[(divisor >> 14) & 0x7];
+	return DIV_ROUND_CLOSEST(base, 2 * divisor3);
+}
+
 static u32 ftdi_232bm_baud_to_divisor(int baud)
 {
 	 return ftdi_232bm_baud_base_to_divisor(baud, 48000000);
 }
 
+static int ftdi_232bm_divisor_to_baud(u32 divisor)
+{
+	return ftdi_232bm_divisor_base_to_baud(divisor, 48000000);
+}
+
 static u32 ftdi_2232h_baud_base_to_divisor(int baud, int base)
 {
 	static const unsigned char divfrac[8] = { 0, 3, 2, 4, 1, 5, 6, 7 };
@@ -1244,11 +1299,32 @@  static u32 ftdi_2232h_baud_base_to_divisor(int baud, int base)
 	return divisor;
 }
 
+static int ftdi_2232h_divisor_base_to_baud(u32 divisor, int base)
+{
+	static const unsigned char divfrac_inv[8] = { 0, 4, 2, 1, 3, 5, 6, 7 };
+	u32 divisor3;
+
+	divisor &= GENMASK(16, 0);
+	/* Deal with special cases for highest baud rates. */
+	if (divisor == 0)
+		divisor = 1;		/* 1.0 */
+	else if (divisor == 1)
+		divisor = 0x4001;	/* 1.5 */
+	divisor3 = (GENMASK(13, 0) & divisor) << 3;
+	divisor3 |= divfrac_inv[(divisor >> 14) & 0x7];
+	return DIV_ROUND_CLOSEST(8 * base, 10 * divisor3);
+}
+
 static u32 ftdi_2232h_baud_to_divisor(int baud)
 {
 	 return ftdi_2232h_baud_base_to_divisor(baud, 120000000);
 }
 
+static int ftdi_2232h_divisor_to_baud(u32 divisor)
+{
+	return ftdi_2232h_divisor_base_to_baud(divisor, 120000000);
+}
+
 #define set_mctrl(port, set)		update_mctrl((port), (set), 0)
 #define clear_mctrl(port, clear)	update_mctrl((port), 0, (clear))
 
@@ -1342,6 +1418,7 @@  static u32 get_ftdi_divisor(struct tty_struct *tty,
 			}
 			div_okay = 0;
 		}
+		baud = ftdi_sdio_divisor_to_baud(div_value);
 		break;
 	case FT8U232AM: /* 8U232AM chip */
 		if (baud >= 183 && baud <= 3000000) {
@@ -1352,6 +1429,7 @@  static u32 get_ftdi_divisor(struct tty_struct *tty,
 			div_value = ftdi_232am_baud_to_divisor(baud);
 			div_okay = 0;
 		}
+		baud = ftdi_232am_divisor_to_baud(div_value);
 		break;
 	case FT232BM: /* FT232BM chip */
 	case FT2232C: /* FT2232C chip */
@@ -1375,22 +1453,27 @@  static u32 get_ftdi_divisor(struct tty_struct *tty,
 			div_value = ftdi_232bm_baud_to_divisor(baud);
 			div_okay = 0;
 		}
+		baud = ftdi_232bm_divisor_to_baud(div_value);
 		break;
 	case FT2232H: /* FT2232H chip */
 	case FT4232H: /* FT4232H chip */
 	case FT232H:  /* FT232H chip */
 		if ((baud <= 12000000) && (baud >= 1200)) {
 			div_value = ftdi_2232h_baud_to_divisor(baud);
+			baud = ftdi_2232h_divisor_to_baud(div_value);
 		} else if (baud >= 183 && baud < 1200) {
 			div_value = ftdi_232bm_baud_to_divisor(baud);
+			baud = ftdi_232bm_divisor_to_baud(div_value);
 		} else {
 			dev_dbg(dev, "%s - Baud rate too high!\n", __func__);
 			if (old_baud >= 183 && old_baud < 1200) {
 				baud = old_baud;
 				div_value = ftdi_232bm_baud_to_divisor(baud);
+				baud = ftdi_232bm_divisor_to_baud(div_value);
 			} else {
 				baud = (old_baud >= 1200 && old_baud <= 12000000) ? old_baud : 9600;
 				div_value = ftdi_2232h_baud_to_divisor(baud);
+				baud = ftdi_2232h_divisor_to_baud(div_value);
 			}
 			div_okay = 0;
 		}