arm64: renesas: r8a779g3: Reset PCIe before next stage on Retronix R-Car V4H Sparrow Hawk

Fully reset both PCIe controllers before booting the next stage on
Retronix R-Car V4H Sparrow Hawk board. This is necessary especially
in case U-Boot brought up the PCIe controllers, at which point the
next stage might be confused by the state of the PCIe controller.
The reset has to happen this late and not in the PCIe controller
driver, because the SRCR11 bits seem to affect both controllers.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>

board/renesas/sparrowhawk/sparrowhawk.c

@@ -267,3 +267,30 @@ void renesas_dram_init_banksize(void)
 			gd->bd->bi_dram[bank].size = 0x200000000ULL;
 	}
 }
+
+#define SRCR6			0xe6152c18
+#define SRCR11			0xe6152c2c
+#define SRSTCLR6		0xe6152c98
+#define SRSTCLR11		0xe6152cac
+#define SRCR_PCIEC0_PWR_RESET	BIT(24)
+#define SRCR_PCIEC1_PWR_RESET	BIT(25)
+#define SRCR_PCIEC0_APP_RESET	BIT(21)
+#define SRCR_PCIEC1_APP_RESET	BIT(22)
+
+void board_cleanup_before_linux(void)
+{
+	if (!IS_ENABLED(CONFIG_PCI_RCAR_GEN4))
+		return;
+
+	/* Set cold and application reset for both PCIe cores */
+	writel(SRCR_PCIEC0_PWR_RESET | SRCR_PCIEC1_PWR_RESET, SRCR6);
+	readl(SRCR6);
+	writel(SRCR_PCIEC0_APP_RESET | SRCR_PCIEC1_APP_RESET, SRCR11);
+	readl(SRCR11);
+
+	/* Clear cold and application reset for both PCIe cores */
+	writel(SRCR_PCIEC0_PWR_RESET | SRCR_PCIEC1_PWR_RESET, SRSTCLR6);
+	readl(SRSTCLR6);
+	writel(SRCR_PCIEC0_APP_RESET | SRCR_PCIEC1_APP_RESET, SRSTCLR11);
+	readl(SRSTCLR11);
+}