PCI: brcmstb: support BCM4908 with external PERST# signal controller

BCM4908 uses external MISC block for controlling PERST# signal. Use it
as a reset controller.

Link: https://lore.kernel.org/r/20201210180421.7230-3-zajec5@gmail.comSigned-off-by: NRafał Miłecki <rafal@milecki.pl>
Signed-off-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: NFlorian Fainelli <f.fainelli@gmail.com>

drivers/pci/controller/Kconfig

@@ -273,7 +273,7 @@ config VMD
 
 config PCIE_BRCMSTB
 	tristate "Broadcom Brcmstb PCIe host controller"
-	depends on ARCH_BRCMSTB || ARCH_BCM2835 || COMPILE_TEST
+	depends on ARCH_BRCMSTB || ARCH_BCM2835 || ARCH_BCM4908 || COMPILE_TEST
 	depends on OF
 	depends on PCI_MSI_IRQ_DOMAIN
 	default ARCH_BRCMSTB

drivers/pci/controller/pcie-brcmstb.c

@@ -97,6 +97,7 @@
 
 #define PCIE_MISC_REVISION				0x406c
 #define  BRCM_PCIE_HW_REV_33				0x0303
+#define  BRCM_PCIE_HW_REV_3_20				0x0320
 
 #define PCIE_MISC_CPU_2_PCIE_MEM_WIN0_BASE_LIMIT		0x4070
 #define  PCIE_MISC_CPU_2_PCIE_MEM_WIN0_BASE_LIMIT_LIMIT_MASK	0xfff00000
@@ -187,6 +188,7 @@
 struct brcm_pcie;
 static inline void brcm_pcie_bridge_sw_init_set_7278(struct brcm_pcie *pcie, u32 val);
 static inline void brcm_pcie_bridge_sw_init_set_generic(struct brcm_pcie *pcie, u32 val);
+static inline void brcm_pcie_perst_set_4908(struct brcm_pcie *pcie, u32 val);
 static inline void brcm_pcie_perst_set_7278(struct brcm_pcie *pcie, u32 val);
 static inline void brcm_pcie_perst_set_generic(struct brcm_pcie *pcie, u32 val);
 
@@ -203,6 +205,7 @@ enum {
 
 enum pcie_type {
 	GENERIC,
+	BCM4908,
 	BCM7278,
 	BCM2711,
 };
@@ -227,6 +230,13 @@ static const struct pcie_cfg_data generic_cfg = {
 	.bridge_sw_init_set = brcm_pcie_bridge_sw_init_set_generic,
 };
 
+static const struct pcie_cfg_data bcm4908_cfg = {
+	.offsets	= pcie_offsets,
+	.type		= BCM4908,
+	.perst_set	= brcm_pcie_perst_set_4908,
+	.bridge_sw_init_set = brcm_pcie_bridge_sw_init_set_generic,
+};
+
 static const int pcie_offset_bcm7278[] = {
 	[RGR1_SW_INIT_1] = 0xc010,
 	[EXT_CFG_INDEX] = 0x9000,
@@ -279,6 +289,7 @@ struct brcm_pcie {
 	const int		*reg_offsets;
 	enum pcie_type		type;
 	struct reset_control	*rescal;
+	struct reset_control	*perst_reset;
 	int			num_memc;
 	u64			memc_size[PCIE_BRCM_MAX_MEMC];
 	u32			hw_rev;
@@ -735,6 +746,17 @@ static inline void brcm_pcie_bridge_sw_init_set_7278(struct brcm_pcie *pcie, u32
 	writel(tmp, pcie->base + PCIE_RGR1_SW_INIT_1(pcie));
 }
 
+static inline void brcm_pcie_perst_set_4908(struct brcm_pcie *pcie, u32 val)
+{
+	if (WARN_ONCE(!pcie->perst_reset, "missing PERST# reset controller\n"))
+		return;
+
+	if (val)
+		reset_control_assert(pcie->perst_reset);
+	else
+		reset_control_deassert(pcie->perst_reset);
+}
+
 static inline void brcm_pcie_perst_set_7278(struct brcm_pcie *pcie, u32 val)
 {
 	u32 tmp;
@@ -1194,6 +1216,7 @@ static int brcm_pcie_remove(struct platform_device *pdev)
 
 static const struct of_device_id brcm_pcie_match[] = {
 	{ .compatible = "brcm,bcm2711-pcie", .data = &bcm2711_cfg },
+	{ .compatible = "brcm,bcm4908-pcie", .data = &bcm4908_cfg },
 	{ .compatible = "brcm,bcm7211-pcie", .data = &generic_cfg },
 	{ .compatible = "brcm,bcm7278-pcie", .data = &bcm7278_cfg },
 	{ .compatible = "brcm,bcm7216-pcie", .data = &bcm7278_cfg },
@@ -1250,6 +1273,11 @@ static int brcm_pcie_probe(struct platform_device *pdev)
 		clk_disable_unprepare(pcie->clk);
 		return PTR_ERR(pcie->rescal);
 	}
+	pcie->perst_reset = devm_reset_control_get_optional_exclusive(&pdev->dev, "perst");
+	if (IS_ERR(pcie->perst_reset)) {
+		clk_disable_unprepare(pcie->clk);
+		return PTR_ERR(pcie->perst_reset);
+	}
 
 	ret = reset_control_deassert(pcie->rescal);
 	if (ret)
@@ -1267,6 +1295,10 @@ static int brcm_pcie_probe(struct platform_device *pdev)
 		goto fail;
 
 	pcie->hw_rev = readl(pcie->base + PCIE_MISC_REVISION);
+	if (pcie->type == BCM4908 && pcie->hw_rev >= BRCM_PCIE_HW_REV_3_20) {
+		dev_err(pcie->dev, "hardware revision with unsupported PERST# setup\n");
+		goto fail;
+	}
 
 	msi_np = of_parse_phandle(pcie->np, "msi-parent", 0);
 	if (pci_msi_enabled() && msi_np == pcie->np) {