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Message-Id: <20250505230624.2692522-168-sashal@kernel.org>
Date: Mon, 5 May 2025 19:05:40 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
stable@...r.kernel.org
Cc: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>,
Geert Uytterhoeven <geert+renesas@...der.be>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Sasha Levin <sashal@...nel.org>,
jirislaby@...nel.org,
p.zabel@...gutronix.de,
wsa+renesas@...g-engineering.com,
zack.rusin@...adcom.com,
namcao@...utronix.de,
prabhakar.mahadev-lad.rj@...renesas.com,
linux-serial@...r.kernel.org
Subject: [PATCH AUTOSEL 6.1 168/212] serial: sh-sci: Update the suspend/resume support
From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
[ Upstream commit 22a6984c5b5df8eab864d7f3e8b94d5a554d31ab ]
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()/sci_console_restore() functions were 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@...renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@...der.be>
Link: https://lore.kernel.org/r/20250207113313.545432-1-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
drivers/tty/serial/sh-sci.c | 71 +++++++++++++++++++++++++++++++++++--
1 file changed, 69 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index e2dfca4c2eff8..191136dcb94d0 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -105,6 +105,15 @@ 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;
@@ -135,6 +144,8 @@ 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;
@@ -154,6 +165,7 @@ 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;
@@ -3252,6 +3264,7 @@ 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);
@@ -3400,13 +3413,57 @@ static int sci_probe(struct platform_device *dev)
return 0;
}
+static void sci_console_save(struct sci_port *s)
+{
+ struct sci_suspend_regs *regs = &s->suspend_regs;
+ struct uart_port *port = &s->port;
+
+ if (sci_getreg(port, SCSMR)->size)
+ regs->scsmr = sci_serial_in(port, SCSMR);
+ if (sci_getreg(port, SCSCR)->size)
+ regs->scscr = sci_serial_in(port, SCSCR);
+ if (sci_getreg(port, SCFCR)->size)
+ regs->scfcr = sci_serial_in(port, SCFCR);
+ if (sci_getreg(port, SCSPTR)->size)
+ regs->scsptr = sci_serial_in(port, SCSPTR);
+ if (sci_getreg(port, SCBRR)->size)
+ regs->scbrr = sci_serial_in(port, SCBRR);
+ if (sci_getreg(port, SEMR)->size)
+ regs->semr = sci_serial_in(port, SEMR);
+}
+
+static void sci_console_restore(struct sci_port *s)
+{
+ struct sci_suspend_regs *regs = &s->suspend_regs;
+ struct uart_port *port = &s->port;
+
+ if (sci_getreg(port, SCSMR)->size)
+ sci_serial_out(port, SCSMR, regs->scsmr);
+ if (sci_getreg(port, SCSCR)->size)
+ sci_serial_out(port, SCSCR, regs->scscr);
+ if (sci_getreg(port, SCFCR)->size)
+ sci_serial_out(port, SCFCR, regs->scfcr);
+ if (sci_getreg(port, SCSPTR)->size)
+ sci_serial_out(port, SCSPTR, regs->scsptr);
+ if (sci_getreg(port, SCBRR)->size)
+ sci_serial_out(port, SCBRR, regs->scbrr);
+ if (sci_getreg(port, SEMR)->size)
+ 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(sport);
+ else
+ return reset_control_assert(sport->rstc);
+ }
+
return 0;
}
@@ -3414,8 +3471,18 @@ 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_restore(sport);
+ } else {
+ int ret = reset_control_deassert(sport->rstc);
+
+ if (ret)
+ return ret;
+ }
+
uart_resume_port(&sci_uart_driver, &sport->port);
+ }
return 0;
}
--
2.39.5
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