linux-kernel - [PATCH 2/3] PCI: brcmstb: Acommodate newer SOCs with next-gen PCIe inbound mapping

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Message-Id: <20250703215314.3971473-3-james.quinlan@broadcom.com>
Date: Thu,  3 Jul 2025 17:53:12 -0400
From: Jim Quinlan <james.quinlan@...adcom.com>
To: linux-pci@...r.kernel.org,
	Nicolas Saenz Julienne <nsaenz@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Cyril Brulebois <kibi@...ian.org>,
	bcm-kernel-feedback-list@...adcom.com,
	jim2101024@...il.com,
	james.quinlan@...adcom.com
Cc: Florian Fainelli <florian.fainelli@...adcom.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	Manivannan Sadhasivam <mani@...nel.org>,
	Rob Herring <robh@...nel.org>,
	linux-rpi-kernel@...ts.infradead.org (moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE),
	linux-arm-kernel@...ts.infradead.org (moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE),
	linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 2/3] PCI: brcmstb: Acommodate newer SOCs with next-gen PCIe inbound mapping

New SoCs are coming that are not encumbered with a baroque internal memory
mapping scheme or power-of-two restrictions on the sizes of inbound
regsions.  Enable the driver to use these SoCs.

Signed-off-by: Jim Quinlan <james.quinlan@...adcom.com>
---
 drivers/pci/controller/pcie-brcmstb.c | 61 ++++++++++++++++++++++++++-
 1 file changed, 60 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
index 5c8aa5e36338..362ac083e112 100644
--- a/drivers/pci/controller/pcie-brcmstb.c
+++ b/drivers/pci/controller/pcie-brcmstb.c
@@ -152,6 +152,8 @@
 
 #define PCIE_MSI_INTR2_BASE		0x4500
 
+#define PCIE_MISC2_BAR1_CONFIG_SIZE				0x4700
+
 /* Offsets from INTR2_CPU and MSI_INTR2 BASE offsets */
 #define  MSI_INT_STATUS			0x0
 #define  MSI_INT_CLR			0x8
@@ -282,6 +284,15 @@ enum pcie_soc_base {
  */
 #define IS_CM_SOC(t) ((t) == BCM3162 || (t) == BCM33940 || (t) == BCM3392)
 
+/*
+ * Newer chips (NG is "Next Generation") have simplified the design of how
+ * inbound regions are mapped to system memory as compared to previous STB
+ * designs.  In addition, the inbound window size is not restricted to be a
+ * power of two.  Such systems may or may not have an IOMMU between the RC
+ * and memory.
+ */
+#define IS_NG_PCI_SOC(t) (0)
+
 struct inbound_win {
 	u64 size;
 	u64 pci_offset;
@@ -1008,7 +1019,8 @@ static int brcm_pcie_get_inbound_wins(struct brcm_pcie *pcie,
 		 * memory.  That being said, each window's size must still
 		 * be a power of two.
 		 */
-		if (pcie->cfg->soc_base == BCM7712 || IS_CM_SOC(pcie->cfg->soc_base))
+		if (pcie->cfg->soc_base == BCM7712 || IS_CM_SOC(pcie->cfg->soc_base)
+		    || IS_NG_PCI_SOC(pcie->cfg->soc_base))
 			add_inbound_win(b++, &n, size, cpu_start, pcie_start);
 
 		if (n > pcie->cfg->num_inbound_wins)
@@ -1020,6 +1032,22 @@ static int brcm_pcie_get_inbound_wins(struct brcm_pcie *pcie,
 		return -EINVAL;
 	}
 
+	if (IS_NG_PCI_SOC(pcie->cfg->soc_base)) {
+		/*
+		 * STB NG SoCs may still be limited with three inbound
+		 * windows, and if so, the last one should be disabled.
+		 */
+		if (pcie->cfg->num_inbound_wins == 3) {
+			n = 2;
+			add_inbound_win(b++, &n, 0, 0, 0);
+		}
+		/*
+		 * NG SoCs do not have internal mapping system that enables
+		 * multiple memory controllers, so return now.
+		 */
+		return n;
+	}
+
 	/*
 	 * 7712, CM, and newer chips do not have an internal memory
 	 * mapping system that enables multiple memory controllers.  As
@@ -1120,6 +1148,17 @@ static u32 brcm_ubus_reg_offset(int bar)
 		return PCIE_MISC_UBUS_BAR4_CONFIG_REMAP + 8 * (bar - 4);
 }
 
+/*
+ * NG SoCs have configurable inbound region size registers (as opposed to
+ * having to set them to a power of two).  There are multiple contiguous
+ * registers, one for each inbound window.  This function provides the
+ * register offset for a specific window.
+ */
+static unsigned int brcm_calc_config_size_reg_offset(int bar)
+{
+	return PCIE_MISC2_BAR1_CONFIG_SIZE + (bar - 1) * 4;
+}
+
 static void set_inbound_win_registers(struct brcm_pcie *pcie,
 				      const struct inbound_win *inbound_wins,
 				      u8 num_inbound_wins)
@@ -1134,6 +1173,24 @@ static void set_inbound_win_registers(struct brcm_pcie *pcie,
 		u32 reg_offset = brcm_bar_reg_offset(i);
 		u32 tmp = lower_32_bits(pci_offset);
 
+		if (IS_NG_PCI_SOC(pcie->cfg->soc_base)) {
+			/* PCIe address */
+			writel(lower_32_bits(pci_offset), base + reg_offset);
+			writel(upper_32_bits(pci_offset), base + reg_offset + 4);
+
+			/* Size of region */
+			reg_offset = brcm_calc_config_size_reg_offset(i);
+			/* Register value has granularity of 4k units */
+			writel(size >> 12, base + reg_offset);
+
+			/* CPU address */
+			reg_offset = brcm_ubus_reg_offset(i);
+			writel(lower_32_bits(cpu_addr), base + reg_offset);
+			writel(upper_32_bits(cpu_addr), base + reg_offset + 4);
+
+			continue;
+		}
+
 		u32p_replace_bits(&tmp, brcm_pcie_encode_ibar_size(size),
 				  PCIE_MISC_RC_BAR1_CONFIG_LO_SIZE_MASK);
 
@@ -1264,6 +1321,8 @@ static int brcm_pcie_setup(struct brcm_pcie *pcie)
 	 */
 	if (IS_CM_SOC(pcie->cfg->soc_base))
 		pcie->msi_target_addr = BRCM_MSI_TARGET_ADDR_FOR_CM;
+	else if (IS_NG_PCI_SOC(pcie->cfg->soc_base))
+		pcie->msi_target_addr = BRCM_MSI_TARGET_ADDR_GT_4GB;
 	else if (inbound_wins[2].pci_offset >= SZ_4G ||
 		 (inbound_wins[2].size + inbound_wins[2].pci_offset) < SZ_4G)
 		pcie->msi_target_addr = BRCM_MSI_TARGET_ADDR_LT_4GB;
-- 
2.34.1