| Message ID | 1494834539-17523-7-git-send-email-aisheng.dong@nxp.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 2017-05-15 00:48, Dong Aisheng wrote: > On new LPUART versions, the oversampling ratio for the receiver can be > changed from 4x (00011) to 32x (11111) which could help us get a more > accurate baud rate divider. > > The idea is to use the best OSR (over-sampling rate) possible. > Note, OSR is typically hard-set to 16 in other LPUART instantiations. > Loop to find the best OSR value possible, one that generates minimum > baud diff iterate through the rest of the supported values of OSR. > > Currently only i.MX7ULP is using it. > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Cc: Jiri Slaby <jslaby@suse.com> > Cc: Stefan Agner <stefan@agner.ch> > Cc: Mingkai Hu <Mingkai.Hu@nxp.com> > Cc: Yangbo Lu <yangbo.lu@nxp.com> > Acked-by: Fugang Duan <fugang.duan@nxp.com> > Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com> > --- > drivers/tty/serial/fsl_lpuart.c | 85 ++++++++++++++++++++++++++++++++++++++--- > 1 file changed, 79 insertions(+), 6 deletions(-) > > diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c > index 107d0911..bda4b0c 100644 > --- a/drivers/tty/serial/fsl_lpuart.c > +++ b/drivers/tty/serial/fsl_lpuart.c > @@ -140,6 +140,8 @@ > #define UARTBAUD_SBNS 0x00002000 > #define UARTBAUD_SBR 0x00000000 > #define UARTBAUD_SBR_MASK 0x1fff > +#define UARTBAUD_OSR_MASK 0x1f > +#define UARTBAUD_OSR_SHIFT 24 > > #define UARTSTAT_LBKDIF 0x80000000 > #define UARTSTAT_RXEDGIF 0x40000000 > @@ -1506,6 +1508,72 @@ lpuart_set_termios(struct uart_port *port, > struct ktermios *termios, > } > > static void > +lpuart32_serial_setbrg(struct lpuart_port *sport, unsigned int baudrate) > +{ > + u32 sbr, osr, baud_diff, tmp_osr, tmp_sbr, tmp_diff, tmp; > + u32 clk = sport->port.uartclk; > + > + /* > + * The idea is to use the best OSR (over-sampling rate) possible. > + * Note, OSR is typically hard-set to 16 in other LPUART instantiations. > + * Loop to find the best OSR value possible, one that generates minimum > + * baud_diff iterate through the rest of the supported values of OSR. > + * > + * Calculation Formula: > + * Baud Rate = baud clock / ((OSR+1) × SBR) > + */ > + baud_diff = baudrate; > + osr = 0; > + sbr = 0; > + > + for (tmp_osr = 4; tmp_osr <= 32; tmp_osr++) { > + /* calculate the temporary sbr value */ > + tmp_sbr = (clk / (baudrate * tmp_osr)); > + if (tmp_sbr == 0) > + tmp_sbr = 1; > + > + /* > + * calculate the baud rate difference based on the temporary > + * osr and sbr values > + */ > + tmp_diff = clk / (tmp_osr * tmp_sbr) - baudrate; > + > + /* select best values between sbr and sbr+1 */ > + tmp = clk / (tmp_osr * (tmp_sbr + 1)); > + if (tmp_diff > (baudrate - tmp)) { > + tmp_diff = baudrate - tmp; > + tmp_sbr++; > + } > + > + if (tmp_diff <= baud_diff) { > + baud_diff = tmp_diff; > + osr = tmp_osr; > + sbr = tmp_sbr; > + } > + } > + > + /* handle buadrate outside acceptable rate */ > + if (baud_diff > ((baudrate / 100) * 3)) > + dev_warn(sport->port.dev, > + "unacceptable baud rate difference of more than 3%%\n"); > + > + tmp = lpuart32_read(sport->port.membase + UARTBAUD); > + > + if ((osr > 3) && (osr < 8)) > + tmp |= UARTBAUD_BOTHEDGE; > + > + tmp &= ~(UARTBAUD_OSR_MASK << UARTBAUD_OSR_SHIFT); > + tmp |= (((osr-1) & UARTBAUD_OSR_MASK) << UARTBAUD_OSR_SHIFT); > + > + tmp &= ~UARTBAUD_SBR_MASK; > + tmp |= sbr & UARTBAUD_SBR_MASK; > + > + tmp &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE); > + > + lpuart32_write(tmp, sport->port.membase + UARTBAUD); > +} > + > +static void > lpuart32_set_termios(struct uart_port *port, struct ktermios *termios, > struct ktermios *old) > { > @@ -1611,12 +1679,17 @@ lpuart32_set_termios(struct uart_port *port, > struct ktermios *termios, > lpuart32_write(old_ctrl & ~(UARTCTRL_TE | UARTCTRL_RE), > sport->port.membase + UARTCTRL); > > - sbr = sport->port.uartclk / (16 * baud); > - bd &= ~UARTBAUD_SBR_MASK; > - bd |= sbr & UARTBAUD_SBR_MASK; > - bd |= UARTBAUD_BOTHEDGE; > - bd &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE); > - lpuart32_write(bd, sport->port.membase + UARTBAUD); > + if (of_device_is_compatible(port->dev->of_node, "fsl,imx7ulp-lpuart")) { Shouldn't we be consequent here and also use a flag in the soc data instead of of_device_is_compatible...? Btw, instead of using 3 bools, I would prefer using a single flags like your patchset is proposing for the GPIO driver, what do you think? -- Stefan > + lpuart32_serial_setbrg(sport, baud); > + } else { > + sbr = sport->port.uartclk / (16 * baud); > + bd &= ~UARTBAUD_SBR_MASK; > + bd |= sbr & UARTBAUD_SBR_MASK; > + bd |= UARTBAUD_BOTHEDGE; > + bd &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE); > + lpuart32_write(bd, sport->port.membase + UARTBAUD); > + } > + > lpuart32_write(modem, sport->port.membase + UARTMODIR); > lpuart32_write(ctrl, sport->port.membase + UARTCTRL); > /* restore control register */
On Mon, May 15, 2017 at 10:06:41AM -0700, Stefan Agner wrote: > On 2017-05-15 00:48, Dong Aisheng wrote: > > On new LPUART versions, the oversampling ratio for the receiver can be > > changed from 4x (00011) to 32x (11111) which could help us get a more > > accurate baud rate divider. > > > > The idea is to use the best OSR (over-sampling rate) possible. > > Note, OSR is typically hard-set to 16 in other LPUART instantiations. > > Loop to find the best OSR value possible, one that generates minimum > > baud diff iterate through the rest of the supported values of OSR. > > > > Currently only i.MX7ULP is using it. > > > > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > > Cc: Jiri Slaby <jslaby@suse.com> > > Cc: Stefan Agner <stefan@agner.ch> > > Cc: Mingkai Hu <Mingkai.Hu@nxp.com> > > Cc: Yangbo Lu <yangbo.lu@nxp.com> > > Acked-by: Fugang Duan <fugang.duan@nxp.com> > > Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com> > > --- > > drivers/tty/serial/fsl_lpuart.c | 85 ++++++++++++++++++++++++++++++++++++++--- > > 1 file changed, 79 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c > > index 107d0911..bda4b0c 100644 > > --- a/drivers/tty/serial/fsl_lpuart.c > > +++ b/drivers/tty/serial/fsl_lpuart.c > > @@ -140,6 +140,8 @@ > > #define UARTBAUD_SBNS 0x00002000 > > #define UARTBAUD_SBR 0x00000000 > > #define UARTBAUD_SBR_MASK 0x1fff > > +#define UARTBAUD_OSR_MASK 0x1f > > +#define UARTBAUD_OSR_SHIFT 24 > > > > #define UARTSTAT_LBKDIF 0x80000000 > > #define UARTSTAT_RXEDGIF 0x40000000 > > @@ -1506,6 +1508,72 @@ lpuart_set_termios(struct uart_port *port, > > struct ktermios *termios, > > } > > > > static void > > +lpuart32_serial_setbrg(struct lpuart_port *sport, unsigned int baudrate) > > +{ > > + u32 sbr, osr, baud_diff, tmp_osr, tmp_sbr, tmp_diff, tmp; > > + u32 clk = sport->port.uartclk; > > + > > + /* > > + * The idea is to use the best OSR (over-sampling rate) possible. > > + * Note, OSR is typically hard-set to 16 in other LPUART instantiations. > > + * Loop to find the best OSR value possible, one that generates minimum > > + * baud_diff iterate through the rest of the supported values of OSR. > > + * > > + * Calculation Formula: > > + * Baud Rate = baud clock / ((OSR+1) × SBR) > > + */ > > + baud_diff = baudrate; > > + osr = 0; > > + sbr = 0; > > + > > + for (tmp_osr = 4; tmp_osr <= 32; tmp_osr++) { > > + /* calculate the temporary sbr value */ > > + tmp_sbr = (clk / (baudrate * tmp_osr)); > > + if (tmp_sbr == 0) > > + tmp_sbr = 1; > > + > > + /* > > + * calculate the baud rate difference based on the temporary > > + * osr and sbr values > > + */ > > + tmp_diff = clk / (tmp_osr * tmp_sbr) - baudrate; > > + > > + /* select best values between sbr and sbr+1 */ > > + tmp = clk / (tmp_osr * (tmp_sbr + 1)); > > + if (tmp_diff > (baudrate - tmp)) { > > + tmp_diff = baudrate - tmp; > > + tmp_sbr++; > > + } > > + > > + if (tmp_diff <= baud_diff) { > > + baud_diff = tmp_diff; > > + osr = tmp_osr; > > + sbr = tmp_sbr; > > + } > > + } > > + > > + /* handle buadrate outside acceptable rate */ > > + if (baud_diff > ((baudrate / 100) * 3)) > > + dev_warn(sport->port.dev, > > + "unacceptable baud rate difference of more than 3%%\n"); > > + > > + tmp = lpuart32_read(sport->port.membase + UARTBAUD); > > + > > + if ((osr > 3) && (osr < 8)) > > + tmp |= UARTBAUD_BOTHEDGE; > > + > > + tmp &= ~(UARTBAUD_OSR_MASK << UARTBAUD_OSR_SHIFT); > > + tmp |= (((osr-1) & UARTBAUD_OSR_MASK) << UARTBAUD_OSR_SHIFT); > > + > > + tmp &= ~UARTBAUD_SBR_MASK; > > + tmp |= sbr & UARTBAUD_SBR_MASK; > > + > > + tmp &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE); > > + > > + lpuart32_write(tmp, sport->port.membase + UARTBAUD); > > +} > > + > > +static void > > lpuart32_set_termios(struct uart_port *port, struct ktermios *termios, > > struct ktermios *old) > > { > > @@ -1611,12 +1679,17 @@ lpuart32_set_termios(struct uart_port *port, > > struct ktermios *termios, > > lpuart32_write(old_ctrl & ~(UARTCTRL_TE | UARTCTRL_RE), > > sport->port.membase + UARTCTRL); > > > > - sbr = sport->port.uartclk / (16 * baud); > > - bd &= ~UARTBAUD_SBR_MASK; > > - bd |= sbr & UARTBAUD_SBR_MASK; > > - bd |= UARTBAUD_BOTHEDGE; > > - bd &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE); > > - lpuart32_write(bd, sport->port.membase + UARTBAUD); > > + if (of_device_is_compatible(port->dev->of_node, "fsl,imx7ulp-lpuart")) { > > Shouldn't we be consequent here and also use a flag in the soc data > instead of of_device_is_compatible...? > The original purpose is that this is a temporary code and supposed will be deleted later once LS platforms confirmed the new baud setting API works for them as well. That's why i did not make it a property, as i stated in the cover letter. > Btw, instead of using 3 bools, I would prefer using a single flags like > your patchset is proposing for the GPIO driver, what do you think? > Yes, good suggestion. Probably we could convert the below two. .is_32 = true, .is_be = true, But reg_off seems better to be kept. Regards Dong Aisheng > -- > Stefan > > > > + lpuart32_serial_setbrg(sport, baud); > > + } else { > > + sbr = sport->port.uartclk / (16 * baud); > > + bd &= ~UARTBAUD_SBR_MASK; > > + bd |= sbr & UARTBAUD_SBR_MASK; > > + bd |= UARTBAUD_BOTHEDGE; > > + bd &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE); > > + lpuart32_write(bd, sport->port.membase + UARTBAUD); > > + } > > + > > lpuart32_write(modem, sport->port.membase + UARTMODIR); > > lpuart32_write(ctrl, sport->port.membase + UARTCTRL); > > /* restore control register */
On 2017-05-16 20:47, Dong Aisheng wrote: > On Mon, May 15, 2017 at 10:06:41AM -0700, Stefan Agner wrote: >> On 2017-05-15 00:48, Dong Aisheng wrote: >> > On new LPUART versions, the oversampling ratio for the receiver can be >> > changed from 4x (00011) to 32x (11111) which could help us get a more >> > accurate baud rate divider. >> > >> > The idea is to use the best OSR (over-sampling rate) possible. >> > Note, OSR is typically hard-set to 16 in other LPUART instantiations. >> > Loop to find the best OSR value possible, one that generates minimum >> > baud diff iterate through the rest of the supported values of OSR. >> > >> > Currently only i.MX7ULP is using it. >> > >> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> >> > Cc: Jiri Slaby <jslaby@suse.com> >> > Cc: Stefan Agner <stefan@agner.ch> >> > Cc: Mingkai Hu <Mingkai.Hu@nxp.com> >> > Cc: Yangbo Lu <yangbo.lu@nxp.com> >> > Acked-by: Fugang Duan <fugang.duan@nxp.com> >> > Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com> >> > --- >> > drivers/tty/serial/fsl_lpuart.c | 85 ++++++++++++++++++++++++++++++++++++++--- >> > 1 file changed, 79 insertions(+), 6 deletions(-) >> > >> > diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c >> > index 107d0911..bda4b0c 100644 >> > --- a/drivers/tty/serial/fsl_lpuart.c >> > +++ b/drivers/tty/serial/fsl_lpuart.c >> > @@ -140,6 +140,8 @@ >> > #define UARTBAUD_SBNS 0x00002000 >> > #define UARTBAUD_SBR 0x00000000 >> > #define UARTBAUD_SBR_MASK 0x1fff >> > +#define UARTBAUD_OSR_MASK 0x1f >> > +#define UARTBAUD_OSR_SHIFT 24 >> > >> > #define UARTSTAT_LBKDIF 0x80000000 >> > #define UARTSTAT_RXEDGIF 0x40000000 >> > @@ -1506,6 +1508,72 @@ lpuart_set_termios(struct uart_port *port, >> > struct ktermios *termios, >> > } >> > >> > static void >> > +lpuart32_serial_setbrg(struct lpuart_port *sport, unsigned int baudrate) >> > +{ >> > + u32 sbr, osr, baud_diff, tmp_osr, tmp_sbr, tmp_diff, tmp; >> > + u32 clk = sport->port.uartclk; >> > + >> > + /* >> > + * The idea is to use the best OSR (over-sampling rate) possible. >> > + * Note, OSR is typically hard-set to 16 in other LPUART instantiations. >> > + * Loop to find the best OSR value possible, one that generates minimum >> > + * baud_diff iterate through the rest of the supported values of OSR. >> > + * >> > + * Calculation Formula: >> > + * Baud Rate = baud clock / ((OSR+1) × SBR) >> > + */ >> > + baud_diff = baudrate; >> > + osr = 0; >> > + sbr = 0; >> > + >> > + for (tmp_osr = 4; tmp_osr <= 32; tmp_osr++) { >> > + /* calculate the temporary sbr value */ >> > + tmp_sbr = (clk / (baudrate * tmp_osr)); >> > + if (tmp_sbr == 0) >> > + tmp_sbr = 1; >> > + >> > + /* >> > + * calculate the baud rate difference based on the temporary >> > + * osr and sbr values >> > + */ >> > + tmp_diff = clk / (tmp_osr * tmp_sbr) - baudrate; >> > + >> > + /* select best values between sbr and sbr+1 */ >> > + tmp = clk / (tmp_osr * (tmp_sbr + 1)); >> > + if (tmp_diff > (baudrate - tmp)) { >> > + tmp_diff = baudrate - tmp; >> > + tmp_sbr++; >> > + } >> > + >> > + if (tmp_diff <= baud_diff) { >> > + baud_diff = tmp_diff; >> > + osr = tmp_osr; >> > + sbr = tmp_sbr; >> > + } >> > + } >> > + >> > + /* handle buadrate outside acceptable rate */ >> > + if (baud_diff > ((baudrate / 100) * 3)) >> > + dev_warn(sport->port.dev, >> > + "unacceptable baud rate difference of more than 3%%\n"); >> > + >> > + tmp = lpuart32_read(sport->port.membase + UARTBAUD); >> > + >> > + if ((osr > 3) && (osr < 8)) >> > + tmp |= UARTBAUD_BOTHEDGE; >> > + >> > + tmp &= ~(UARTBAUD_OSR_MASK << UARTBAUD_OSR_SHIFT); >> > + tmp |= (((osr-1) & UARTBAUD_OSR_MASK) << UARTBAUD_OSR_SHIFT); >> > + >> > + tmp &= ~UARTBAUD_SBR_MASK; >> > + tmp |= sbr & UARTBAUD_SBR_MASK; >> > + >> > + tmp &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE); >> > + >> > + lpuart32_write(tmp, sport->port.membase + UARTBAUD); >> > +} >> > + >> > +static void >> > lpuart32_set_termios(struct uart_port *port, struct ktermios *termios, >> > struct ktermios *old) >> > { >> > @@ -1611,12 +1679,17 @@ lpuart32_set_termios(struct uart_port *port, >> > struct ktermios *termios, >> > lpuart32_write(old_ctrl & ~(UARTCTRL_TE | UARTCTRL_RE), >> > sport->port.membase + UARTCTRL); >> > >> > - sbr = sport->port.uartclk / (16 * baud); >> > - bd &= ~UARTBAUD_SBR_MASK; >> > - bd |= sbr & UARTBAUD_SBR_MASK; >> > - bd |= UARTBAUD_BOTHEDGE; >> > - bd &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE); >> > - lpuart32_write(bd, sport->port.membase + UARTBAUD); >> > + if (of_device_is_compatible(port->dev->of_node, "fsl,imx7ulp-lpuart")) { >> >> Shouldn't we be consequent here and also use a flag in the soc data >> instead of of_device_is_compatible...? >> > > The original purpose is that this is a temporary code and supposed will > be deleted later once LS platforms confirmed the new baud setting API > works for them as well. > > That's why i did not make it a property, as i stated in the cover letter. Ok, I see that is a good reason to not define a new feature property now... But, if you are reasonable sure it should work, I am inclined to say just enable it for LS1021a so it also really gets tested... > >> Btw, instead of using 3 bools, I would prefer using a single flags like >> your patchset is proposing for the GPIO driver, what do you think? >> > > Yes, good suggestion. > Probably we could convert the below two. > .is_32 = true, > .is_be = true, > > But reg_off seems better to be kept. Sounds good! -- Stefan > > Regards > Dong Aisheng > >> -- >> Stefan >> >> >> > + lpuart32_serial_setbrg(sport, baud); >> > + } else { >> > + sbr = sport->port.uartclk / (16 * baud); >> > + bd &= ~UARTBAUD_SBR_MASK; >> > + bd |= sbr & UARTBAUD_SBR_MASK; >> > + bd |= UARTBAUD_BOTHEDGE; >> > + bd &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE); >> > + lpuart32_write(bd, sport->port.membase + UARTBAUD); >> > + } >> > + >> > lpuart32_write(modem, sport->port.membase + UARTMODIR); >> > lpuart32_write(ctrl, sport->port.membase + UARTCTRL); >> > /* restore control register */
On Wed, May 17, 2017 at 10:35:43AM -0700, Stefan Agner wrote: > On 2017-05-16 20:47, Dong Aisheng wrote: > > On Mon, May 15, 2017 at 10:06:41AM -0700, Stefan Agner wrote: > >> On 2017-05-15 00:48, Dong Aisheng wrote: > >> > On new LPUART versions, the oversampling ratio for the receiver can be > >> > changed from 4x (00011) to 32x (11111) which could help us get a more > >> > accurate baud rate divider. > >> > > >> > The idea is to use the best OSR (over-sampling rate) possible. > >> > Note, OSR is typically hard-set to 16 in other LPUART instantiations. > >> > Loop to find the best OSR value possible, one that generates minimum > >> > baud diff iterate through the rest of the supported values of OSR. > >> > > >> > Currently only i.MX7ULP is using it. > >> > > >> > Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > >> > Cc: Jiri Slaby <jslaby@suse.com> > >> > Cc: Stefan Agner <stefan@agner.ch> > >> > Cc: Mingkai Hu <Mingkai.Hu@nxp.com> > >> > Cc: Yangbo Lu <yangbo.lu@nxp.com> > >> > Acked-by: Fugang Duan <fugang.duan@nxp.com> > >> > Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com> > >> > --- > >> > drivers/tty/serial/fsl_lpuart.c | 85 ++++++++++++++++++++++++++++++++++++++--- > >> > 1 file changed, 79 insertions(+), 6 deletions(-) > >> > > >> > diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c > >> > index 107d0911..bda4b0c 100644 > >> > --- a/drivers/tty/serial/fsl_lpuart.c > >> > +++ b/drivers/tty/serial/fsl_lpuart.c > >> > @@ -140,6 +140,8 @@ > >> > #define UARTBAUD_SBNS 0x00002000 > >> > #define UARTBAUD_SBR 0x00000000 > >> > #define UARTBAUD_SBR_MASK 0x1fff > >> > +#define UARTBAUD_OSR_MASK 0x1f > >> > +#define UARTBAUD_OSR_SHIFT 24 > >> > > >> > #define UARTSTAT_LBKDIF 0x80000000 > >> > #define UARTSTAT_RXEDGIF 0x40000000 > >> > @@ -1506,6 +1508,72 @@ lpuart_set_termios(struct uart_port *port, > >> > struct ktermios *termios, > >> > } > >> > > >> > static void > >> > +lpuart32_serial_setbrg(struct lpuart_port *sport, unsigned int baudrate) > >> > +{ > >> > + u32 sbr, osr, baud_diff, tmp_osr, tmp_sbr, tmp_diff, tmp; > >> > + u32 clk = sport->port.uartclk; > >> > + > >> > + /* > >> > + * The idea is to use the best OSR (over-sampling rate) possible. > >> > + * Note, OSR is typically hard-set to 16 in other LPUART instantiations. > >> > + * Loop to find the best OSR value possible, one that generates minimum > >> > + * baud_diff iterate through the rest of the supported values of OSR. > >> > + * > >> > + * Calculation Formula: > >> > + * Baud Rate = baud clock / ((OSR+1) × SBR) > >> > + */ > >> > + baud_diff = baudrate; > >> > + osr = 0; > >> > + sbr = 0; > >> > + > >> > + for (tmp_osr = 4; tmp_osr <= 32; tmp_osr++) { > >> > + /* calculate the temporary sbr value */ > >> > + tmp_sbr = (clk / (baudrate * tmp_osr)); > >> > + if (tmp_sbr == 0) > >> > + tmp_sbr = 1; > >> > + > >> > + /* > >> > + * calculate the baud rate difference based on the temporary > >> > + * osr and sbr values > >> > + */ > >> > + tmp_diff = clk / (tmp_osr * tmp_sbr) - baudrate; > >> > + > >> > + /* select best values between sbr and sbr+1 */ > >> > + tmp = clk / (tmp_osr * (tmp_sbr + 1)); > >> > + if (tmp_diff > (baudrate - tmp)) { > >> > + tmp_diff = baudrate - tmp; > >> > + tmp_sbr++; > >> > + } > >> > + > >> > + if (tmp_diff <= baud_diff) { > >> > + baud_diff = tmp_diff; > >> > + osr = tmp_osr; > >> > + sbr = tmp_sbr; > >> > + } > >> > + } > >> > + > >> > + /* handle buadrate outside acceptable rate */ > >> > + if (baud_diff > ((baudrate / 100) * 3)) > >> > + dev_warn(sport->port.dev, > >> > + "unacceptable baud rate difference of more than 3%%\n"); > >> > + > >> > + tmp = lpuart32_read(sport->port.membase + UARTBAUD); > >> > + > >> > + if ((osr > 3) && (osr < 8)) > >> > + tmp |= UARTBAUD_BOTHEDGE; > >> > + > >> > + tmp &= ~(UARTBAUD_OSR_MASK << UARTBAUD_OSR_SHIFT); > >> > + tmp |= (((osr-1) & UARTBAUD_OSR_MASK) << UARTBAUD_OSR_SHIFT); > >> > + > >> > + tmp &= ~UARTBAUD_SBR_MASK; > >> > + tmp |= sbr & UARTBAUD_SBR_MASK; > >> > + > >> > + tmp &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE); > >> > + > >> > + lpuart32_write(tmp, sport->port.membase + UARTBAUD); > >> > +} > >> > + > >> > +static void > >> > lpuart32_set_termios(struct uart_port *port, struct ktermios *termios, > >> > struct ktermios *old) > >> > { > >> > @@ -1611,12 +1679,17 @@ lpuart32_set_termios(struct uart_port *port, > >> > struct ktermios *termios, > >> > lpuart32_write(old_ctrl & ~(UARTCTRL_TE | UARTCTRL_RE), > >> > sport->port.membase + UARTCTRL); > >> > > >> > - sbr = sport->port.uartclk / (16 * baud); > >> > - bd &= ~UARTBAUD_SBR_MASK; > >> > - bd |= sbr & UARTBAUD_SBR_MASK; > >> > - bd |= UARTBAUD_BOTHEDGE; > >> > - bd &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE); > >> > - lpuart32_write(bd, sport->port.membase + UARTBAUD); > >> > + if (of_device_is_compatible(port->dev->of_node, "fsl,imx7ulp-lpuart")) { > >> > >> Shouldn't we be consequent here and also use a flag in the soc data > >> instead of of_device_is_compatible...? > >> > > > > The original purpose is that this is a temporary code and supposed will > > be deleted later once LS platforms confirmed the new baud setting API > > works for them as well. > > > > That's why i did not make it a property, as i stated in the cover letter. > > Ok, I see that is a good reason to not define a new feature property > now... > > But, if you are reasonable sure it should work, I am inclined to say > just enable it for LS1021a so it also really gets tested... > Okay, i'll take this suggestion to get things started. Thanks Regards Dong Aisheng
diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index 107d0911..bda4b0c 100644 --- a/drivers/tty/serial/fsl_lpuart.c +++ b/drivers/tty/serial/fsl_lpuart.c @@ -140,6 +140,8 @@ #define UARTBAUD_SBNS 0x00002000 #define UARTBAUD_SBR 0x00000000 #define UARTBAUD_SBR_MASK 0x1fff +#define UARTBAUD_OSR_MASK 0x1f +#define UARTBAUD_OSR_SHIFT 24 #define UARTSTAT_LBKDIF 0x80000000 #define UARTSTAT_RXEDGIF 0x40000000 @@ -1506,6 +1508,72 @@ lpuart_set_termios(struct uart_port *port, struct ktermios *termios, } static void +lpuart32_serial_setbrg(struct lpuart_port *sport, unsigned int baudrate) +{ + u32 sbr, osr, baud_diff, tmp_osr, tmp_sbr, tmp_diff, tmp; + u32 clk = sport->port.uartclk; + + /* + * The idea is to use the best OSR (over-sampling rate) possible. + * Note, OSR is typically hard-set to 16 in other LPUART instantiations. + * Loop to find the best OSR value possible, one that generates minimum + * baud_diff iterate through the rest of the supported values of OSR. + * + * Calculation Formula: + * Baud Rate = baud clock / ((OSR+1) × SBR) + */ + baud_diff = baudrate; + osr = 0; + sbr = 0; + + for (tmp_osr = 4; tmp_osr <= 32; tmp_osr++) { + /* calculate the temporary sbr value */ + tmp_sbr = (clk / (baudrate * tmp_osr)); + if (tmp_sbr == 0) + tmp_sbr = 1; + + /* + * calculate the baud rate difference based on the temporary + * osr and sbr values + */ + tmp_diff = clk / (tmp_osr * tmp_sbr) - baudrate; + + /* select best values between sbr and sbr+1 */ + tmp = clk / (tmp_osr * (tmp_sbr + 1)); + if (tmp_diff > (baudrate - tmp)) { + tmp_diff = baudrate - tmp; + tmp_sbr++; + } + + if (tmp_diff <= baud_diff) { + baud_diff = tmp_diff; + osr = tmp_osr; + sbr = tmp_sbr; + } + } + + /* handle buadrate outside acceptable rate */ + if (baud_diff > ((baudrate / 100) * 3)) + dev_warn(sport->port.dev, + "unacceptable baud rate difference of more than 3%%\n"); + + tmp = lpuart32_read(sport->port.membase + UARTBAUD); + + if ((osr > 3) && (osr < 8)) + tmp |= UARTBAUD_BOTHEDGE; + + tmp &= ~(UARTBAUD_OSR_MASK << UARTBAUD_OSR_SHIFT); + tmp |= (((osr-1) & UARTBAUD_OSR_MASK) << UARTBAUD_OSR_SHIFT); + + tmp &= ~UARTBAUD_SBR_MASK; + tmp |= sbr & UARTBAUD_SBR_MASK; + + tmp &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE); + + lpuart32_write(tmp, sport->port.membase + UARTBAUD); +} + +static void lpuart32_set_termios(struct uart_port *port, struct ktermios *termios, struct ktermios *old) { @@ -1611,12 +1679,17 @@ lpuart32_set_termios(struct uart_port *port, struct ktermios *termios, lpuart32_write(old_ctrl & ~(UARTCTRL_TE | UARTCTRL_RE), sport->port.membase + UARTCTRL); - sbr = sport->port.uartclk / (16 * baud); - bd &= ~UARTBAUD_SBR_MASK; - bd |= sbr & UARTBAUD_SBR_MASK; - bd |= UARTBAUD_BOTHEDGE; - bd &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE); - lpuart32_write(bd, sport->port.membase + UARTBAUD); + if (of_device_is_compatible(port->dev->of_node, "fsl,imx7ulp-lpuart")) { + lpuart32_serial_setbrg(sport, baud); + } else { + sbr = sport->port.uartclk / (16 * baud); + bd &= ~UARTBAUD_SBR_MASK; + bd |= sbr & UARTBAUD_SBR_MASK; + bd |= UARTBAUD_BOTHEDGE; + bd &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE); + lpuart32_write(bd, sport->port.membase + UARTBAUD); + } + lpuart32_write(modem, sport->port.membase + UARTMODIR); lpuart32_write(ctrl, sport->port.membase + UARTCTRL); /* restore control register */