| From e4a9d61407a3f578ab35a3f67f745d99c5ee06c3 Mon Sep 17 00:00:00 2001 |
| From: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> |
| Date: Fri, 6 Dec 2013 10:59:20 +0100 |
| Subject: serial: sh-sci: Rework baud rate calculation |
| |
| Computing the baud rate register value requires knowledge of the |
| hardware sampling rate. This information is currently encoded in a baud |
| rate calculation algorithm ID passed through platform data. However, it |
| can be derived from the port type directly in most cases. |
| |
| Compute the sampling rate internally in the driver if the baud rate |
| calculation algorithm ID isn't specified, and allow platforms to |
| override the sampling rate through platform data in special cases (this |
| is only required for SCIFA ports on sh7723 and sh7724, the reason needs |
| to be investigated). |
| |
| Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> |
| Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| Signed-off-by: Simon Horman <horms+renesas@verge.net.au> |
| (cherry picked from commit ec09c5eb491834d4011c72538e58d8b7096076bd) |
| (Queued by Simon Horman for v3.14 but not yet in Linus's tree) |
| Signed-off-by: Simon Horman <horms+renesas@verge.net.au> |
| --- |
| drivers/tty/serial/sh-sci.c | 37 ++++++++++++++++++++++++++++++------- |
| include/linux/serial_sci.h | 2 ++ |
| 2 files changed, 32 insertions(+), 7 deletions(-) |
| |
| diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c |
| index e643df18f48b..35e3225714bc 100644 |
| --- a/drivers/tty/serial/sh-sci.c |
| +++ b/drivers/tty/serial/sh-sci.c |
| @@ -65,6 +65,7 @@ struct sci_port { |
| struct plat_sci_port *cfg; |
| int overrun_bit; |
| unsigned int error_mask; |
| + unsigned int sampling_rate; |
| |
| |
| /* Break timer */ |
| @@ -1750,10 +1751,13 @@ static void sci_shutdown(struct uart_port *port) |
| sci_free_irq(s); |
| } |
| |
| -static unsigned int sci_scbrr_calc(unsigned int algo_id, unsigned int bps, |
| +static unsigned int sci_scbrr_calc(struct sci_port *s, unsigned int bps, |
| unsigned long freq) |
| { |
| - switch (algo_id) { |
| + if (s->sampling_rate) |
| + return DIV_ROUND_CLOSEST(freq, s->sampling_rate * bps) - 1; |
| + |
| + switch (s->cfg->scbrr_algo_id) { |
| case SCBRR_ALGO_1: |
| return freq / (16 * bps); |
| case SCBRR_ALGO_2: |
| @@ -1843,12 +1847,11 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios, |
| |
| baud = uart_get_baud_rate(port, termios, old, 0, max_baud); |
| if (likely(baud && port->uartclk)) { |
| - if (s->cfg->scbrr_algo_id == SCBRR_ALGO_6) { |
| + if (s->cfg->type == PORT_HSCIF) { |
| sci_baud_calc_hscif(baud, port->uartclk, &t, &srr, |
| &cks); |
| } else { |
| - t = sci_scbrr_calc(s->cfg->scbrr_algo_id, baud, |
| - port->uartclk); |
| + t = sci_scbrr_calc(s, baud, port->uartclk); |
| for (cks = 0; t >= 256 && cks <= 3; cks++) |
| t >>= 2; |
| } |
| @@ -2092,6 +2095,7 @@ static int sci_init_single(struct platform_device *dev, |
| { |
| struct uart_port *port = &sci_port->port; |
| const struct resource *res; |
| + unsigned int sampling_rate; |
| unsigned int i; |
| int ret; |
| |
| @@ -2143,28 +2147,47 @@ static int sci_init_single(struct platform_device *dev, |
| case PORT_SCIFB: |
| port->fifosize = 256; |
| sci_port->overrun_bit = 9; |
| + sampling_rate = 16; |
| break; |
| case PORT_HSCIF: |
| port->fifosize = 128; |
| + sampling_rate = 0; |
| sci_port->overrun_bit = 0; |
| break; |
| case PORT_SCIFA: |
| port->fifosize = 64; |
| sci_port->overrun_bit = 9; |
| + sampling_rate = 16; |
| break; |
| case PORT_SCIF: |
| port->fifosize = 16; |
| - if (p->regtype == SCIx_SH7705_SCIF_REGTYPE) |
| + if (p->regtype == SCIx_SH7705_SCIF_REGTYPE) { |
| sci_port->overrun_bit = 9; |
| - else |
| + sampling_rate = 16; |
| + } else { |
| sci_port->overrun_bit = 0; |
| + sampling_rate = 32; |
| + } |
| break; |
| default: |
| port->fifosize = 1; |
| sci_port->overrun_bit = 5; |
| + sampling_rate = 32; |
| break; |
| } |
| |
| + /* Set the sampling rate if the baud rate calculation algorithm isn't |
| + * specified. |
| + */ |
| + if (p->scbrr_algo_id == SCBRR_ALGO_NONE) { |
| + /* SCIFA on sh7723 and sh7724 need a custom sampling rate that |
| + * doesn't match the SoC datasheet, this should be investigated. |
| + * Let platform data override the sampling rate for now. |
| + */ |
| + sci_port->sampling_rate = p->sampling_rate ? p->sampling_rate |
| + : sampling_rate; |
| + } |
| + |
| if (!early) { |
| sci_port->iclk = clk_get(&dev->dev, "sci_ick"); |
| if (IS_ERR(sci_port->iclk)) { |
| diff --git a/include/linux/serial_sci.h b/include/linux/serial_sci.h |
| index efd4727ccd67..0bac5628e650 100644 |
| --- a/include/linux/serial_sci.h |
| +++ b/include/linux/serial_sci.h |
| @@ -11,6 +11,7 @@ |
| #define SCIx_NOT_SUPPORTED (-1) |
| |
| enum { |
| + SCBRR_ALGO_NONE, /* Compute sampling rate in the driver */ |
| SCBRR_ALGO_1, /* clk / (16 * bps) */ |
| SCBRR_ALGO_2, /* DIV_ROUND_CLOSEST(clk, 32 * bps) - 1 */ |
| SCBRR_ALGO_3, /* clk / (8 * bps) */ |
| @@ -134,6 +135,7 @@ struct plat_sci_port { |
| upf_t flags; /* UPF_* flags */ |
| unsigned long capabilities; /* Port features/capabilities */ |
| |
| + unsigned int sampling_rate; |
| unsigned int scbrr_algo_id; /* SCBRR calculation algo */ |
| unsigned int scscr; /* SCSCR initialization */ |
| |
| -- |
| 1.8.5.rc3 |
| |