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Groups > linux.kernel > #1273373
| From | Geert Uytterhoeven <geert+renesas@glider.be> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 20/25] serial: sh-sci: Add support for optional BRG on (H)SCIF |
| Date | 2015-11-19 19:50 +0100 |
| Message-ID | <qwCro-4G9-23@gated-at.bofh.it> (permalink) |
| References | <qwChI-4Cb-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
Add support for the Baud Rate Generator for External Clock (BRG), as
found on some SCIF and HSCIF variants, which can improve baud rate range
and accuracy.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
drivers/tty/serial/sh-sci.c | 82 ++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 77 insertions(+), 5 deletions(-)
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index f88aac684ed1e3b6..6b8f1675b9f6fadb 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -80,6 +80,8 @@ enum {
enum SCI_CLKS {
SCI_FCK, /* Functional Clock */
SCI_SCK, /* Optional External Clock */
+ SCI_INT_CLK, /* Optional BRG Internal Clock Source */
+ SCI_SCIF_CLK, /* Optional BRG External Clock Source */
SCI_NUM_CLKS
};
@@ -1955,6 +1957,40 @@ static int sci_sck_calc(struct sci_port *s, unsigned int bps,
return min_err;
}
+static int sci_brg_calc(struct sci_port *s, unsigned int bps,
+ unsigned long freq, unsigned int *dlr,
+ unsigned int *srr)
+{
+ unsigned int min_sr, max_sr, sr, dl;
+ int err, min_err = INT_MAX;
+
+ if (s->sampling_rate) {
+ /* SCIF has a fixed sampling rate */
+ min_sr = max_sr = s->sampling_rate / 2;
+ } else {
+ /* HSCIF has a variable 1/(8..32) sampling rate */
+ min_sr = 8;
+ max_sr = 32;
+ }
+
+ for (sr = max_sr; sr >= min_sr; sr--) {
+ dl = DIV_ROUND_CLOSEST(freq, sr * bps);
+ dl = clamp(dl, 1U, 65535U);
+
+ err = DIV_ROUND_CLOSEST(freq, sr * dl) - bps;
+ if (abs(err) >= abs(min_err))
+ continue;
+
+ min_err = err;
+ *dlr = dl;
+ *srr = sr - 1;
+ }
+
+ dev_dbg(s->port.dev, "BRG: %u%+d bps using DL %u SR %u\n", bps,
+ min_err, *dlr, *srr + 1);
+ return min_err;
+}
+
/* calculate sample rate, BRR, and clock select */
static int sci_scbrr_calc(struct sci_port *s, unsigned int bps,
unsigned int *brr, unsigned int *srr,
@@ -2036,8 +2072,8 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
struct ktermios *old)
{
unsigned int baud, smr_val = 0, scr_val = 0, i;
- unsigned int brr = 255, cks = 0, srr = 15, sccks = 0;
- unsigned int brr1 = 255, cks1 = 0, srr1 = 15;
+ unsigned int brr = 255, cks = 0, srr = 15, dl = 0, sccks = 0;
+ unsigned int brr1 = 255, cks1 = 0, srr1 = 15, dl1 = 0;
struct sci_port *s = to_sci_port(port);
const struct plat_sci_reg *reg;
int min_err = INT_MAX, err;
@@ -2089,6 +2125,38 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
}
}
+ /* Optional BRG External Clock Source */
+ if (s->clk_rates[SCI_SCIF_CLK] && sci_getreg(port, SCDL)->size) {
+ err = sci_brg_calc(s, baud, s->clk_rates[SCI_SCIF_CLK], &dl1,
+ &srr1);
+ if (abs(err) < abs(min_err)) {
+ best_clk = SCI_SCIF_CLK;
+ scr_val = SCSCR_CKE1;
+ sccks = 0;
+ min_err = err;
+ dl = dl1;
+ srr = srr1;
+ if (!err)
+ goto done;
+ }
+ }
+
+ /* Optional BRG Internal Clock Source */
+ if (s->clk_rates[SCI_INT_CLK] && sci_getreg(port, SCDL)->size) {
+ err = sci_brg_calc(s, baud, s->clk_rates[SCI_INT_CLK], &dl1,
+ &srr1);
+ if (abs(err) < abs(min_err)) {
+ best_clk = SCI_INT_CLK;
+ scr_val = SCSCR_CKE1;
+ sccks = SCCKS_XIN;
+ min_err = err;
+ dl = dl1;
+ srr = srr1;
+ if (!min_err)
+ goto done;
+ }
+ }
+
/* Functional Clock and standard Bit Rate Register */
err = sci_scbrr_calc(s, baud, &brr1, &srr1, &cks1);
if (abs(err) < abs(min_err)) {
@@ -2108,8 +2176,10 @@ done:
sci_port_enable(s);
/* Program the optional External Baud Rate Generator (BRG) first */
- if (best_clk >= 0 && sci_getreg(port, SCCKS)->size)
+ if (best_clk >= 0 && sci_getreg(port, SCCKS)->size) {
+ serial_port_out(port, SCDL, dl);
serial_port_out(port, SCCKS, sccks);
+ }
sci_reset(port);
@@ -2118,8 +2188,8 @@ done:
if (best_clk >= 0) {
smr_val |= cks;
dev_dbg(port->dev,
- "SCR 0x%x SMR 0x%x BRR %u CKS 0x%x SRR %u\n",
- scr_val, smr_val, brr, sccks, srr);
+ "SCR 0x%x SMR 0x%x BRR %u CKS 0x%x DL %u SRR %u\n",
+ scr_val, smr_val, brr, sccks, dl, srr);
serial_port_out(port, SCSCR, scr_val);
serial_port_out(port, SCSMR, smr_val);
serial_port_out(port, SCBRR, brr);
@@ -2357,6 +2427,8 @@ static int sci_init_clocks(struct sci_port *sci_port, struct device *dev)
const char *clk_names[] = {
[SCI_FCK] = "fck",
[SCI_SCK] = "sck",
+ [SCI_INT_CLK] = "int_clk",
+ [SCI_SCIF_CLK] = "scif_clk",
};
struct clk *clk;
unsigned int i;
--
1.9.1
--
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[PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
[PATCH 22/25] ARM: shmobile: koelsch dts: Enable SCIF_CLK frequency and pins Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
[PATCH 16/25] serial: sh-sci: Correct SCIF type on RZ/A1H Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
[PATCH 20/25] serial: sh-sci: Add support for optional BRG on (H)SCIF Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
[PATCH 18/25] serial: sh-sci: Prepare for multiple clocks and baud rate generators Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
Re: [PATCH 18/25] serial: sh-sci: Prepare for multiple clocks and baud rate generators Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 22:10 +0100
Re: [PATCH 18/25] serial: sh-sci: Prepare for multiple clocks and baud rate generators Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 09:00 +0100
Re: [PATCH 18/25] serial: sh-sci: Prepare for multiple clocks and baud rate generators Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-20 15:50 +0100
Re: [PATCH 18/25] serial: sh-sci: Prepare for multiple clocks and baud rate generators Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 16:20 +0100
Re: [PATCH 18/25] serial: sh-sci: Prepare for multiple clocks and baud rate generators Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-20 16:40 +0100
[PATCH 05/25] serial: sh-sci: Drop unused frame_len parameter for sci_baud_calc_hscif() Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
[PATCH 23/25] arm64: renesas: r8a7795 dtsi: Add BRG support for (H)SCIF Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
Re: [PATCH 23/25] arm64: renesas: r8a7795 dtsi: Add BRG support for (H)SCIF Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 22:10 +0100
Re: [PATCH 23/25] arm64: renesas: r8a7795 dtsi: Add BRG support for (H)SCIF Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 09:20 +0100
[PATCH 02/25] serial: sh-sci: Update DT binding documentation for BRG support Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
Re: [PATCH 02/25] serial: sh-sci: Update DT binding documentation for BRG support Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 21:30 +0100
Re: [PATCH 02/25] serial: sh-sci: Update DT binding documentation for BRG support Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-19 21:50 +0100
Re: [PATCH 02/25] serial: sh-sci: Update DT binding documentation for BRG support Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 22:20 +0100
Re: [PATCH 02/25] serial: sh-sci: Update DT binding documentation for BRG support Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 09:00 +0100
[PATCH 04/25] serial: sh-sci: Grammar s/Get ... for/Get ... from/ Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
[PATCH 17/25] serial: sh-sci: Correct SCIF type on R-Car for BRG Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
Re: [PATCH 17/25] serial: sh-sci: Correct SCIF type on R-Car for BRG Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 22:00 +0100
Re: [PATCH 17/25] serial: sh-sci: Correct SCIF type on R-Car for BRG Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 08:50 +0100
Re: [PATCH 17/25] serial: sh-sci: Correct SCIF type on R-Car for BRG Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-20 16:00 +0100
Re: [PATCH 17/25] serial: sh-sci: Correct SCIF type on R-Car for BRG Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-20 16:40 +0100
Re: [PATCH 17/25] serial: sh-sci: Correct SCIF type on R-Car for BRG Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 16:40 +0100
[PATCH 06/25] serial: sh-sci: Don't overwrite clock selection in serial_console_write() Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
[PATCH 13/25] serial: sh-sci: Take into account sampling rate for max baud rate Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
[PATCH 21/25] ARM: shmobile: r8a7791 dtsi: Add BRG support for (H)SCIF Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
[PATCH 14/25] serial: sh-sci: Add BRG register definitions Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
Re: [PATCH 14/25] serial: sh-sci: Add BRG register definitions Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 21:50 +0100
[PATCH 07/25] serial: sh-sci: Convert from clk_get() to devm_clk_get() Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
Re: [PATCH 07/25] serial: sh-sci: Convert from clk_get() to devm_clk_get() Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 21:40 +0100
[PATCH 01/25] serial: sh-sci: Update DT binding documentation for external clock input Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
Re: [PATCH 01/25] serial: sh-sci: Update DT binding documentation for external clock input Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 21:20 +0100
Re: [PATCH 01/25] serial: sh-sci: Update DT binding documentation for external clock input Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 21:30 +0100
Re: [PATCH 01/25] serial: sh-sci: Update DT binding documentation for external clock input Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-19 21:50 +0100
Re: [PATCH 01/25] serial: sh-sci: Update DT binding documentation for external clock input Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 22:20 +0100
Re: [PATCH 01/25] serial: sh-sci: Update DT binding documentation for external clock input Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 09:10 +0100
Re: [PATCH 01/25] serial: sh-sci: Update DT binding documentation for external clock input Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-19 21:40 +0100
[PATCH 03/25] serial: sh-sci: Drop useless check for zero sampling_rate Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
[PATCH 24/25] arm64: renesas: salvator-x dts: Enable SCIF_CLK frequency and pins Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
[PATCH 19/25] serial: sh-sci: Add support for optional external (H)SCK input Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 19:50 +0100
[PATCH 11/25] serial: sh-sci: Avoid calculating the receive margin for HSCIF Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 20:00 +0100
[PATCH 12/25] serial: sh-sci: Merge sci_scbrr_calc() and sci_baud_calc_hscif() Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 20:00 +0100
[PATCH 10/25] serial: sh-sci: Improve bit rate error calculation for HSCIF Geert Uytterhoeven <geert+renesas@glider.be> - 2015-11-19 20:00 +0100
Re: [PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-19 22:10 +0100
Re: [PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 09:30 +0100
Re: [PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-20 10:00 +0100
Re: [PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 10:10 +0100
Re: [PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-11-20 16:00 +0100
Re: [PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 16:40 +0100
Re: [PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Geert Uytterhoeven <geert@linux-m68k.org> - 2015-11-20 10:10 +0100
Re: [PATCH 00/25] serial: sh-sci: Add external clock and BRG Support Simon Horman <horms@verge.net.au> - 2015-11-24 03:50 +0100
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