drivers/tty/serial/sh-sci.c | 55 +++++++++++++++++++++++++++++++++++-- 1 file changed, 53 insertions(+), 2 deletions(-)
From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
The Renesas RZ/G3S supports a power saving mode where power to most of the
SoC components is turned off. When returning from this power saving mode,
SoC components need to be re-configured.
The SCIFs on the Renesas RZ/G3S need to be re-configured as well when
returning from this power saving mode. The sh-sci code already configures
the SCIF clocks, power domain and registers by calling uart_resume_port()
in sci_resume(). On suspend path the SCIF UART ports are suspended
accordingly (by calling uart_suspend_port() in sci_suspend()). The only
missing setting is the reset signal. For this assert/de-assert the reset
signal on driver suspend/resume.
In case the no_console_suspend is specified by the user, the registers need
to be saved on suspend path and restore on resume path. To do this the
sci_console_save_restore() function was added. There is no need to
cache/restore the status or FIFO registers. Only the control registers.
The registers that will be saved/restored on suspend/resume are
specified by the struct sci_suspend_regs data structure.
Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---
The v4 of this patch was part of a series with 4 patches. As the rest of
the patches were applied I dropped the cover letter. The v4 cover letter
is located here:
https://lore.kernel.org/all/20250120130936.1080069-1-claudiu.beznea.uj@bp.renesas.com
Changes in v5:
- fixed typo in patch description
- adjusted the patch description to reflect the new patch content
- added struct sci_suspend_regs and dropped the suspend_cacheable
flag introduced previously in struct plat_sci_reg; along with it
the updates in sci_port_params[] were also dropped;
also, the function (now sci_console_save_restore()) that saves
and restores the registers content was adjusted accordingly
- s/sci_console_setup/sci_console_save_restore/g
Changes in v4:
- none
Changes in v3:
- none
Changes in v2:
- rebased on top of the update version of patch 2/8 from
this series
drivers/tty/serial/sh-sci.c | 55 +++++++++++++++++++++++++++++++++++--
1 file changed, 53 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index b1ea48f38248..03349bc31080 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -104,6 +104,15 @@ struct plat_sci_reg {
u8 offset, size;
};
+struct sci_suspend_regs {
+ u16 scsmr;
+ u16 scscr;
+ u16 scfcr;
+ u16 scsptr;
+ u8 scbrr;
+ u8 semr;
+};
+
struct sci_port_params {
const struct plat_sci_reg regs[SCIx_NR_REGS];
unsigned int fifosize;
@@ -134,6 +143,8 @@ struct sci_port {
struct dma_chan *chan_tx;
struct dma_chan *chan_rx;
+ struct reset_control *rstc;
+
#ifdef CONFIG_SERIAL_SH_SCI_DMA
struct dma_chan *chan_tx_saved;
struct dma_chan *chan_rx_saved;
@@ -153,6 +164,7 @@ struct sci_port {
int rx_trigger;
struct timer_list rx_fifo_timer;
int rx_fifo_timeout;
+ struct sci_suspend_regs suspend_regs;
u16 hscif_tot;
bool has_rtscts;
@@ -3374,6 +3386,7 @@ static struct plat_sci_port *sci_parse_dt(struct platform_device *pdev,
}
sp = &sci_ports[id];
+ sp->rstc = rstc;
*dev_id = id;
p->type = SCI_OF_TYPE(data);
@@ -3546,13 +3559,41 @@ static int sci_probe(struct platform_device *dev)
return 0;
}
+static void sci_console_save_restore(struct sci_port *s, bool save)
+{
+ struct sci_suspend_regs *regs = &s->suspend_regs;
+ struct uart_port *port = &s->port;
+
+ if (save) {
+ regs->scsmr = sci_serial_in(port, SCSMR);
+ regs->scscr = sci_serial_in(port, SCSCR);
+ regs->scfcr = sci_serial_in(port, SCFCR);
+ regs->scsptr = sci_serial_in(port, SCSPTR);
+ regs->scbrr = sci_serial_in(port, SCBRR);
+ regs->semr = sci_serial_in(port, SEMR);
+ } else {
+ sci_serial_out(port, SCSMR, regs->scsmr);
+ sci_serial_out(port, SCSCR, regs->scscr);
+ sci_serial_out(port, SCFCR, regs->scfcr);
+ sci_serial_out(port, SCSPTR, regs->scsptr);
+ sci_serial_out(port, SCBRR, regs->scbrr);
+ sci_serial_out(port, SEMR, regs->semr);
+ }
+}
+
static __maybe_unused int sci_suspend(struct device *dev)
{
struct sci_port *sport = dev_get_drvdata(dev);
- if (sport)
+ if (sport) {
uart_suspend_port(&sci_uart_driver, &sport->port);
+ if (!console_suspend_enabled && uart_console(&sport->port))
+ sci_console_save_restore(sport, true);
+ else
+ return reset_control_assert(sport->rstc);
+ }
+
return 0;
}
@@ -3560,8 +3601,18 @@ static __maybe_unused int sci_resume(struct device *dev)
{
struct sci_port *sport = dev_get_drvdata(dev);
- if (sport)
+ if (sport) {
+ if (!console_suspend_enabled && uart_console(&sport->port)) {
+ sci_console_save_restore(sport, false);
+ } else {
+ int ret = reset_control_deassert(sport->rstc);
+
+ if (ret)
+ return ret;
+ }
+
uart_resume_port(&sci_uart_driver, &sport->port);
+ }
return 0;
}
--
2.43.0Hi Claudiu,
On Wed, 5 Feb 2025 at 10:31, Claudiu <claudiu.beznea@tuxon.dev> wrote:
> From: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
>
> The Renesas RZ/G3S supports a power saving mode where power to most of the
> SoC components is turned off. When returning from this power saving mode,
> SoC components need to be re-configured.
>
> The SCIFs on the Renesas RZ/G3S need to be re-configured as well when
> returning from this power saving mode. The sh-sci code already configures
> the SCIF clocks, power domain and registers by calling uart_resume_port()
> in sci_resume(). On suspend path the SCIF UART ports are suspended
> accordingly (by calling uart_suspend_port() in sci_suspend()). The only
> missing setting is the reset signal. For this assert/de-assert the reset
> signal on driver suspend/resume.
>
> In case the no_console_suspend is specified by the user, the registers need
> to be saved on suspend path and restore on resume path. To do this the
> sci_console_save_restore() function was added. There is no need to
> cache/restore the status or FIFO registers. Only the control registers.
> The registers that will be saved/restored on suspend/resume are
> specified by the struct sci_suspend_regs data structure.
>
> Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
> ---
>
> The v4 of this patch was part of a series with 4 patches. As the rest of
> the patches were applied I dropped the cover letter. The v4 cover letter
> is located here:
> https://lore.kernel.org/all/20250120130936.1080069-1-claudiu.beznea.uj@bp.renesas.com
>
> Changes in v5:
> - fixed typo in patch description
> - adjusted the patch description to reflect the new patch content
> - added struct sci_suspend_regs and dropped the suspend_cacheable
> flag introduced previously in struct plat_sci_reg; along with it
> the updates in sci_port_params[] were also dropped;
> also, the function (now sci_console_save_restore()) that saves
> and restores the registers content was adjusted accordingly
> - s/sci_console_setup/sci_console_save_restore/g
Thanks for the update!
> --- a/drivers/tty/serial/sh-sci.c
> +++ b/drivers/tty/serial/sh-sci.c
> @@ -3546,13 +3559,41 @@ static int sci_probe(struct platform_device *dev)
> return 0;
> }
>
> +static void sci_console_save_restore(struct sci_port *s, bool save)
> +{
> + struct sci_suspend_regs *regs = &s->suspend_regs;
> + struct uart_port *port = &s->port;
> +
> + if (save) {
> + regs->scsmr = sci_serial_in(port, SCSMR);
> + regs->scscr = sci_serial_in(port, SCSCR);
> + regs->scfcr = sci_serial_in(port, SCFCR);
> + regs->scsptr = sci_serial_in(port, SCSPTR);
> + regs->scbrr = sci_serial_in(port, SCBRR);
> + regs->semr = sci_serial_in(port, SEMR);
The SCFCR, SCSPTR, and SEMR registers do not exist on all
variants. Hence you should call sci_getreg() and check if
plat_sci_reg.size is non-zero first, else you will trigger the WARN()
in sci_serial_in().
> + } else {
> + sci_serial_out(port, SCSMR, regs->scsmr);
> + sci_serial_out(port, SCSCR, regs->scscr);
> + sci_serial_out(port, SCFCR, regs->scfcr);
> + sci_serial_out(port, SCSPTR, regs->scsptr);
> + sci_serial_out(port, SCBRR, regs->scbrr);
> + sci_serial_out(port, SEMR, regs->semr);
Likewise for sci_serial_out().
> + }
> +}
Given there's nothing really shared anymore, I would split this in
separate sci_console_save() and sci_console_restore() functions.
The rest LGTM.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
Hi Claudiu,
On Thu, 6 Feb 2025 at 13:47, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> On Wed, 5 Feb 2025 at 10:31, Claudiu <claudiu.beznea@tuxon.dev> wrote:
> > @@ -3546,13 +3559,41 @@ static int sci_probe(struct platform_device *dev)
> > return 0;
> > }
> >
> > +static void sci_console_save_restore(struct sci_port *s, bool save)
> > +{
> > + struct sci_suspend_regs *regs = &s->suspend_regs;
> > + struct uart_port *port = &s->port;
> > +
> > + if (save) {
> > + regs->scsmr = sci_serial_in(port, SCSMR);
> > + regs->scscr = sci_serial_in(port, SCSCR);
> > + regs->scfcr = sci_serial_in(port, SCFCR);
> > + regs->scsptr = sci_serial_in(port, SCSPTR);
> > + regs->scbrr = sci_serial_in(port, SCBRR);
> > + regs->semr = sci_serial_in(port, SEMR);
>
> The SCFCR, SCSPTR, and SEMR registers do not exist on all
> variants. Hence you should call sci_getreg() and check if
> plat_sci_reg.size is non-zero first, else you will trigger the WARN()
> in sci_serial_in().
As expected, the WARN() is triggered on any R-Car platform during
system suspend.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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