PCI: brcmstb: Set bus max burst size by chip type

The proper value of the parameter SCB_MAX_BURST_SIZE varies per chip.  The
2711 family requires 128B whereas other devices can employ 512.  The
assignment is complicated by the fact that the values for this two-bit
field have different meanings;

  Value   Type_Generic    Type_7278

     00       Reserved         128B
     01           128B         256B
     10           256B         512B
     11           512B     Reserved

Link: https://lore.kernel.org/r/20200911175232.19016-10-james.quinlan@broadcom.com
Signed-off-by: Jim Quinlan <jquinlan@broadcom.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>

drivers/pci/controller/pcie-brcmstb.c

@@ -55,7 +55,7 @@
 #define  PCIE_MISC_MISC_CTRL_SCB_ACCESS_EN_MASK		0x1000
 #define  PCIE_MISC_MISC_CTRL_CFG_READ_UR_MODE_MASK	0x2000
 #define  PCIE_MISC_MISC_CTRL_MAX_BURST_SIZE_MASK	0x300000
-#define  PCIE_MISC_MISC_CTRL_MAX_BURST_SIZE_128		0x0
+
 #define  PCIE_MISC_MISC_CTRL_SCB0_SIZE_MASK		0xf8000000
 #define  PCIE_MISC_MISC_CTRL_SCB1_SIZE_MASK		0x07c00000
 #define  PCIE_MISC_MISC_CTRL_SCB2_SIZE_MASK		0x0000001f
@@ -867,7 +867,7 @@ static int brcm_pcie_setup(struct brcm_pcie *pcie)
 	int num_out_wins = 0;
 	u16 nlw, cls, lnksta;
 	int i, ret, memc;
-	u32 tmp, aspm_support;
+	u32 tmp, burst, aspm_support;
 
 	/* Reset the bridge */
 	pcie->bridge_sw_init_set(pcie, 1);
@@ -882,11 +882,22 @@ static int brcm_pcie_setup(struct brcm_pcie *pcie)
 	/* Wait for SerDes to be stable */
 	usleep_range(100, 200);
 
+	/*
+	 * SCB_MAX_BURST_SIZE is a two bit field.  For GENERIC chips it
+	 * is encoded as 0=128, 1=256, 2=512, 3=Rsvd, for BCM7278 it
+	 * is encoded as 0=Rsvd, 1=128, 2=256, 3=512.
+	 */
+	if (pcie->type == BCM2711)
+		burst = 0x0; /* 128B */
+	else if (pcie->type == BCM7278)
+		burst = 0x3; /* 512 bytes */
+	else
+		burst = 0x2; /* 512 bytes */
+
 	/* Set SCB_MAX_BURST_SIZE, CFG_READ_UR_MODE, SCB_ACCESS_EN */
 	u32p_replace_bits(&tmp, 1, PCIE_MISC_MISC_CTRL_SCB_ACCESS_EN_MASK);
 	u32p_replace_bits(&tmp, 1, PCIE_MISC_MISC_CTRL_CFG_READ_UR_MODE_MASK);
-	u32p_replace_bits(&tmp, PCIE_MISC_MISC_CTRL_MAX_BURST_SIZE_128,
-			  PCIE_MISC_MISC_CTRL_MAX_BURST_SIZE_MASK);
+	u32p_replace_bits(&tmp, burst, PCIE_MISC_MISC_CTRL_MAX_BURST_SIZE_MASK);
 	writel(tmp, base + PCIE_MISC_MISC_CTRL);
 
 	ret = brcm_pcie_get_rc_bar2_size_and_offset(pcie, &rc_bar2_size,