[PATCH v4 08/10] PCI: brcmstb: Adjust PHY PLL setup to use a 54MHz input refclk

[Stanimir Varbanov <svarbanov@xxxxxxx>]

The default input reference clock for the PHY PLL is 100Mhz, except for
some devices where it is 54Mhz like bcm2712C1 and bcm2712D0.

To implement this adjustments introduce a new .post_setup op in
pcie_cfg_data and call it at the end of brcm_pcie_setup function.

The bcm2712 .post_setup callback implements the required MDIO writes that
switch the PLL refclk and also change PHY PM clock period.

Without this RPi5 PCIex1 is unable to enumerate endpoint devices on
the expansion connector.

Signed-off-by: Stanimir Varbanov <svarbanov@xxxxxxx>
---
v3 -> v4:
 - Improved patch description (Florian)

 drivers/pci/controller/pcie-brcmstb.c | 42 +++++++++++++++++++++++++++
 1 file changed, 42 insertions(+)

diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
index d970a76aa9ef..2571dcc14560 100644
--- a/drivers/pci/controller/pcie-brcmstb.c
+++ b/drivers/pci/controller/pcie-brcmstb.c
@@ -55,6 +55,10 @@
 #define PCIE_RC_DL_MDIO_WR_DATA				0x1104
 #define PCIE_RC_DL_MDIO_RD_DATA				0x1108
 
+#define PCIE_RC_PL_PHY_CTL_15				0x184c
+#define  PCIE_RC_PL_PHY_CTL_15_DIS_PLL_PD_MASK		0x400000
+#define  PCIE_RC_PL_PHY_CTL_15_PM_CLK_PERIOD_MASK	0xff
+
 #define PCIE_MISC_MISC_CTRL				0x4008
 #define  PCIE_MISC_MISC_CTRL_PCIE_RCB_64B_MODE_MASK	0x80
 #define  PCIE_MISC_MISC_CTRL_PCIE_RCB_MPS_MODE_MASK	0x400
@@ -251,6 +255,7 @@ struct pcie_cfg_data {
 	u8 num_inbound_wins;
 	int (*perst_set)(struct brcm_pcie *pcie, u32 val);
 	int (*bridge_sw_init_set)(struct brcm_pcie *pcie, u32 val);
+	int (*post_setup)(struct brcm_pcie *pcie);
 };
 
 struct subdev_regulators {
@@ -826,6 +831,36 @@ static int brcm_pcie_perst_set_generic(struct brcm_pcie *pcie, u32 val)
 	return 0;
 }
 
+static int brcm_pcie_post_setup_bcm2712(struct brcm_pcie *pcie)
+{
+	const u16 data[] = { 0x50b9, 0xbda1, 0x0094, 0x97b4, 0x5030, 0x5030, 0x0007 };
+	const u8 regs[] = { 0x16, 0x17, 0x18, 0x19, 0x1b, 0x1c, 0x1e };
+	int ret, i;
+	u32 tmp;
+
+	/* Allow a 54MHz (xosc) refclk source */
+	ret = brcm_pcie_mdio_write(pcie->base, MDIO_PORT0, SET_ADDR_OFFSET, 0x1600);
+	if (ret < 0)
+		return ret;
+
+	for (i = 0; i < ARRAY_SIZE(regs); i++) {
+		ret = brcm_pcie_mdio_write(pcie->base, MDIO_PORT0, regs[i], data[i]);
+		if (ret < 0)
+			return ret;
+	}
+
+	usleep_range(100, 200);
+
+	/* Fix for L1SS errata */
+	tmp = readl(pcie->base + PCIE_RC_PL_PHY_CTL_15);
+	tmp &= ~PCIE_RC_PL_PHY_CTL_15_PM_CLK_PERIOD_MASK;
+	/* PM clock period is 18.52ns (round down) */
+	tmp |= 0x12;
+	writel(tmp, pcie->base + PCIE_RC_PL_PHY_CTL_15);
+
+	return 0;
+}
+
 static void add_inbound_win(struct inbound_win *b, u8 *count, u64 size,
 			    u64 cpu_addr, u64 pci_offset)
 {
@@ -1189,6 +1224,12 @@ static int brcm_pcie_setup(struct brcm_pcie *pcie)
 		PCIE_RC_CFG_VENDOR_VENDOR_SPECIFIC_REG1_ENDIAN_MODE_BAR2_MASK);
 	writel(tmp, base + PCIE_RC_CFG_VENDOR_VENDOR_SPECIFIC_REG1);
 
+	if (pcie->cfg->post_setup) {
+		ret = pcie->cfg->post_setup(pcie);
+		if (ret < 0)
+			return ret;
+	}
+
 	return 0;
 }
 
@@ -1761,6 +1802,7 @@ static const struct pcie_cfg_data bcm2712_cfg = {
 	.soc_base	= BCM7712,
 	.perst_set	= brcm_pcie_perst_set_7278,
 	.bridge_sw_init_set = brcm_pcie_bridge_sw_init_set_generic,
+	.post_setup	= brcm_pcie_post_setup_bcm2712,
 	.quirks		= CFG_QUIRK_AVOID_BRIDGE_SHUTDOWN,
 	.num_inbound_wins = 10,
 };
-- 
2.43.0