PCI: rzg3s-host: Add SoC-specific configuration and initialization callbacks

Add optional cfg_pre_init, cfg_post_init, and cfg_deinit callbacks
to handle SoC-specific configuration methods. While RZ/G3S uses the Linux
reset framework with dedicated reset lines, other SoC variants like RZ/G3E
control configuration resets through PCIe AXI registers.

As Linux reset bulk API gracefully handles optional NULL reset lines
(num_cfg_resets = 0 for RZ/G3E), the driver continues to use the standard
reset framework when reset lines are available, while custom callbacks
are only invoked when provided.

This provides a balanced pattern where:
- RZ/G3S: Uses callbacks that fall back to the reset framework
- RZ/G3E: Sets num_cfg_resets=0, provides
  cfg_pre_init/cfg_post_init/cfg_deinit

Signed-off-by: John Madieu <john.madieu.xa@bp.renesas.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> # RZ/V2N EVK
Tested-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea.uj@bp.renesas.com>
Link: https://patch.msgid.link/20260306143423.19562-10-john.madieu.xa@bp.renesas.com

Author: John Madieu

drivers/pci/controller/pcie-rzg3s-host.c

@@ -233,6 +233,9 @@ struct rzg3s_pcie_host;
 /**
  * struct rzg3s_pcie_soc_data - SoC specific data
  * @init_phy: PHY initialization function
+ * @config_pre_init: Optional callback for SoC-specific pre-configuration
+ * @config_post_init: Callback for SoC-specific post-configuration
+ * @config_deinit: Callback for SoC-specific de-initialization
  * @power_resets: array with the resets that need to be de-asserted after
  *                power-on
  * @cfg_resets: array with the resets that need to be de-asserted after
@@ -243,6 +246,9 @@ struct rzg3s_pcie_host;
  */
 struct rzg3s_pcie_soc_data {
 	int (*init_phy)(struct rzg3s_pcie_host *host);
+	void (*config_pre_init)(struct rzg3s_pcie_host *host);
+	int (*config_post_init)(struct rzg3s_pcie_host *host);
+	int (*config_deinit)(struct rzg3s_pcie_host *host);
 	const char * const *power_resets;
 	const char * const *cfg_resets;
 	struct rzg3s_sysc_info sysc_info;
@@ -1109,6 +1115,18 @@ static int rzg3s_pcie_config_init(struct rzg3s_pcie_host *host)
 	return 0;
 }
 
+static int rzg3s_pcie_config_post_init(struct rzg3s_pcie_host *host)
+{
+	return reset_control_bulk_deassert(host->data->num_cfg_resets,
+					   host->cfg_resets);
+}
+
+static int rzg3s_pcie_config_deinit(struct rzg3s_pcie_host *host)
+{
+	return reset_control_bulk_assert(host->data->num_cfg_resets,
+					 host->cfg_resets);
+}
+
 static void rzg3s_pcie_irq_init(struct rzg3s_pcie_host *host)
 {
 	/*
@@ -1257,22 +1275,26 @@ static int rzg3s_pcie_host_init(struct rzg3s_pcie_host *host)
 	u32 val;
 	int ret;
 
+	/* SoC-specific pre-configuration */
+	if (host->data->config_pre_init)
+		host->data->config_pre_init(host);
+
 	/* Initialize the PCIe related registers */
 	ret = rzg3s_pcie_config_init(host);
 	if (ret)
-		return ret;
+		goto config_deinit;
 
 	ret = rzg3s_pcie_host_init_port(host);
 	if (ret)
-		return ret;
+		goto config_deinit;
 
 	/* Initialize the interrupts */
 	rzg3s_pcie_irq_init(host);
 
-	ret = reset_control_bulk_deassert(host->data->num_cfg_resets,
-					  host->cfg_resets);
+	/* SoC-specific post-configuration */
+	ret = host->data->config_post_init(host);
 	if (ret)
-		goto disable_port_refclk;
+		goto config_deinit_and_refclk;
 
 	/* Wait for link up */
 	ret = readl_poll_timeout(host->axi + RZG3S_PCI_PCSTAT1, val,
@@ -1281,18 +1303,20 @@ static int rzg3s_pcie_host_init(struct rzg3s_pcie_host *host)
 				 PCIE_LINK_WAIT_SLEEP_MS * MILLI *
 				 PCIE_LINK_WAIT_MAX_RETRIES);
 	if (ret)
-		goto cfg_resets_deassert;
+		goto config_deinit_post;
 
 	val = readl_relaxed(host->axi + RZG3S_PCI_PCSTAT2);
 	dev_info(host->dev, "PCIe link status [0x%x]\n", val);
 
 	return 0;
 
-cfg_resets_deassert:
-	reset_control_bulk_assert(host->data->num_cfg_resets,
-				  host->cfg_resets);
-disable_port_refclk:
+config_deinit_post:
+	host->data->config_deinit(host);
+config_deinit_and_refclk:
 	clk_disable_unprepare(host->port.refclk);
+config_deinit:
+	if (host->data->config_pre_init)
+		host->data->config_deinit(host);
 	return ret;
 }
 
@@ -1653,7 +1677,7 @@ static int rzg3s_pcie_probe(struct platform_device *pdev)
 
 host_probe_teardown:
 	rzg3s_pcie_teardown_irqdomain(host);
-	reset_control_bulk_assert(host->data->num_cfg_resets, host->cfg_resets);
+	host->data->config_deinit(host);
 rpm_put:
 	pm_runtime_put_sync(dev);
 rpm_disable:
@@ -1686,15 +1710,15 @@ static int rzg3s_pcie_suspend_noirq(struct device *dev)
 
 	clk_disable_unprepare(port->refclk);
 
-	ret = reset_control_bulk_assert(data->num_cfg_resets,
-					host->cfg_resets);
+	/* SoC-specific de-initialization */
+	ret = data->config_deinit(host);
 	if (ret)
 		goto refclk_restore;
 
 	ret = reset_control_bulk_assert(data->num_power_resets,
 					host->power_resets);
 	if (ret)
-		goto cfg_resets_restore;
+		goto config_reinit;
 
 	ret = rzg3s_sysc_config_func(sysc, RZG3S_SYSC_FUNC_ID_RST_RSM_B, 0);
 	if (ret)
@@ -1706,9 +1730,10 @@ static int rzg3s_pcie_suspend_noirq(struct device *dev)
 power_resets_restore:
 	reset_control_bulk_deassert(data->num_power_resets,
 				    host->power_resets);
-cfg_resets_restore:
-	reset_control_bulk_deassert(data->num_cfg_resets,
-				    host->cfg_resets);
+config_reinit:
+	if (data->config_pre_init)
+		data->config_pre_init(host);
+	data->config_post_init(host);
 refclk_restore:
 	clk_prepare_enable(port->refclk);
 	pm_runtime_resume_and_get(dev);
@@ -1773,6 +1798,8 @@ static const struct rzg3s_pcie_soc_data rzg3s_soc_data = {
 	.num_power_resets = ARRAY_SIZE(rzg3s_soc_power_resets),
 	.cfg_resets = rzg3s_soc_cfg_resets,
 	.num_cfg_resets = ARRAY_SIZE(rzg3s_soc_cfg_resets),
+	.config_post_init = rzg3s_pcie_config_post_init,
+	.config_deinit = rzg3s_pcie_config_deinit,
 	.init_phy = rzg3s_soc_pcie_init_phy,
 	.sysc_info = {
 		.functions = {