pinctrl: renesas: rzg2l: Add suspend/resume support for Schmitt control registers

Renesas RZ/G3E supports a power-saving mode where power to most of the
SoC components is lost, including the PIN controller.  Save and restore
the Schmitt control register contents to ensure the functionality is
preserved after a suspend/resume cycle.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Tested-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com> # on RZ/G3S
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/20250819084022.20512-1-biju.das.jz@bp.renesas.com
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

Author: bijudas

drivers/pinctrl/renesas/pinctrl-rzg2l.c

@@ -321,6 +321,7 @@ struct rzg2l_pinctrl_pin_settings {
  * @iolh: IOLH registers cache
  * @pupd: PUPD registers cache
  * @ien: IEN registers cache
+ * @smt: SMT registers cache
  * @sd_ch: SD_CH registers cache
  * @eth_poc: ET_POC registers cache
  * @oen: Output Enable register cache
@@ -334,6 +335,7 @@ struct rzg2l_pinctrl_reg_cache {
 	u32	*iolh[2];
 	u32	*ien[2];
 	u32	*pupd[2];
+	u32	*smt;
 	u8	sd_ch[2];
 	u8	eth_poc[2];
 	u8	oen;
@@ -2704,6 +2706,10 @@ static int rzg2l_pinctrl_reg_cache_alloc(struct rzg2l_pinctrl *pctrl)
 	if (!cache->pfc)
 		return -ENOMEM;
 
+	cache->smt = devm_kcalloc(pctrl->dev, nports, sizeof(*cache->smt), GFP_KERNEL);
+	if (!cache->smt)
+		return -ENOMEM;
+
 	for (u8 i = 0; i < 2; i++) {
 		u32 n_dedicated_pins = pctrl->data->n_dedicated_pins;
 
@@ -2965,7 +2971,7 @@ static void rzg2l_pinctrl_pm_setup_regs(struct rzg2l_pinctrl *pctrl, bool suspen
 	struct rzg2l_pinctrl_reg_cache *cache = pctrl->cache;
 
 	for (u32 port = 0; port < nports; port++) {
-		bool has_iolh, has_ien, has_pupd;
+		bool has_iolh, has_ien, has_pupd, has_smt;
 		u32 off, caps;
 		u8 pincnt;
 		u64 cfg;
@@ -2978,6 +2984,7 @@ static void rzg2l_pinctrl_pm_setup_regs(struct rzg2l_pinctrl *pctrl, bool suspen
 		has_iolh = !!(caps & (PIN_CFG_IOLH_A | PIN_CFG_IOLH_B | PIN_CFG_IOLH_C));
 		has_ien = !!(caps & PIN_CFG_IEN);
 		has_pupd = !!(caps & PIN_CFG_PUPD);
+		has_smt = !!(caps & PIN_CFG_SMT);
 
 		if (suspend)
 			RZG2L_PCTRL_REG_ACCESS32(suspend, pctrl->base + PFC(off), cache->pfc[port]);
@@ -3016,6 +3023,9 @@ static void rzg2l_pinctrl_pm_setup_regs(struct rzg2l_pinctrl *pctrl, bool suspen
 							 cache->ien[1][port]);
 			}
 		}
+
+		if (has_smt)
+			RZG2L_PCTRL_REG_ACCESS32(suspend, pctrl->base + SMT(off), cache->smt[port]);
 	}
 }