[PATCH v3 3/8] serial: sh-sci: Update the suspend/resume support

Claudiu
2024-11-15T13:44:17Z

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_setup() function was added. There is no need to cache/restore
the status or FIFO registers. Only the control registers. To differentiate
b/w these, the struct sci_port_params::regs was updated with a new member
that specifies if the register needs to be chached on suspend. Only the
RZ_SCIFA instances were updated with this new support as the hardware for
the rest of variants was missing for testing.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
---

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 | 53 ++++++++++++++++++++++++++++++-------
1 file changed, 44 insertions(+), 9 deletions(-)

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index ade151ff39d2..e53496d2708e 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -101,7 +101,7 @@ enum SCI_CLKS {
if ((_port)->sampling_rate_mask & SCI_SR((_sr)))

struct plat_sci_reg {
- u8 offset, size;
+ u8 offset, size, suspend_cacheable;
};

struct sci_port_params {
@@ -134,6 +134,8 @@ 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 +155,7 @@ struct sci_port {
int rx_trigger;
struct timer_list rx_fifo_timer;
int rx_fifo_timeout;
+ unsigned int console_cached_regs[SCIx_NR_REGS];
u16 hscif_tot;

bool has_rtscts;
@@ -298,17 +301,17 @@ static const struct sci_port_params sci_port_params[SCIx_NR_REGTYPES] = {
*/
[SCIx_RZ_SCIFA_REGTYPE] = {
.regs = {
- [SCSMR] = { 0x00, 16 },
- [SCBRR] = { 0x02, 8 },
- [SCSCR] = { 0x04, 16 },
+ [SCSMR] = { 0x00, 16, 1 },
+ [SCBRR] = { 0x02, 8, 1 },
+ [SCSCR] = { 0x04, 16, 1 },
[SCxTDR] = { 0x06, 8 },
[SCxSR] = { 0x08, 16 },
[SCxRDR] = { 0x0A, 8 },
- [SCFCR] = { 0x0C, 16 },
+ [SCFCR] = { 0x0C, 16, 1 },
[SCFDR] = { 0x0E, 16 },
- [SCSPTR] = { 0x10, 16 },
+ [SCSPTR] = { 0x10, 16, 1 },
[SCLSR] = { 0x12, 16 },
- [SEMR] = { 0x14, 8 },
+ [SEMR] = { 0x14, 8, 1 },
},
.fifosize = 16,
.overrun_reg = SCLSR,
@@ -3380,6 +3383,7 @@ 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);
@@ -3507,13 +3511,34 @@ static int sci_probe(struct platform_device *dev)
return 0;
}

+static void sci_console_setup(struct sci_port *s, bool save)
+{
+ for (u16 i = 0; i < SCIx_NR_REGS; i++) {
+ struct uart_port *port = &s->port;
+
+ if (!s->params->regs[i].suspend_cacheable)
+ continue;
+
+ if (save)
+ s->console_cached_regs[i] = sci_serial_in(port, i);
+ else
+ sci_serial_out(port, i, s->console_cached_regs[i]);
+ }
+}
+
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_setup(sport, true);
+ else
+ return reset_control_assert(sport->rstc);
+ }
+
return 0;
}

@@ -3521,8 +3546,18 @@ 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_setup(sport, false);
+ } else {
+ int ret = reset_control_deassert(sport->rstc);
+
+ if (ret)
+ return ret;
+ }
+
uart_resume_port(&sci_uart_driver, &sport->port);
+ }

return 0;
}
--
2.39.2