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serial: sh-sci: Update the suspend/resume support

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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@bp.renesas.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20250207113313.545432-1-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Claudiu Beznea 2025-02-07 13:33:13 +02:00 • committed by Greg Kroah-Hartman
parent 1f0cfc68ad
commit 22a6984c5b
1 changed files with 69 additions and 2 deletions
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71
drivers/tty/serial/sh-sci.c
View file

@ -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 +3559,57 @@ 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;
}
@ -3560,8 +3617,18 @@ 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;
}