PCI: rockchip: Add poll and timeout to wait for PHY PLLs to be locked

The RK3399 PCIe controller should wait until the PHY PLLs are locked.
Add poll and timeout to wait for PHY PLLs to be locked. If they cannot
be locked generate error message and jump to error handler. Accessing
registers in the PHY clock domain when PLLs are not locked causes hang
The PHY PLLs status is checked through a side channel register.
This is documented in the TRM section 17.5.8.1 "PCIe Initialization
Sequence".

Link: https://lore.kernel.org/r/20230418074700.1083505-5-rick.wertenbroek@gmail.com
Fixes: cf590b0 ("PCI: rockchip: Add EP driver for Rockchip PCIe controller")
Tested-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Rick Wertenbroek <rick.wertenbroek@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Cc: stable@vger.kernel.org

Author: rwk-git

drivers/pci/controller/pcie-rockchip.c

@@ -14,6 +14,7 @@
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/gpio/consumer.h>
+#include <linux/iopoll.h>
 #include <linux/of_pci.h>
 #include <linux/phy/phy.h>
 #include <linux/platform_device.h>
@@ -153,6 +154,12 @@ int rockchip_pcie_parse_dt(struct rockchip_pcie *rockchip)
 }
 EXPORT_SYMBOL_GPL(rockchip_pcie_parse_dt);
 
+#define rockchip_pcie_read_addr(addr) rockchip_pcie_read(rockchip, addr)
+/* 100 ms max wait time for PHY PLLs to lock */
+#define RK_PHY_PLL_LOCK_TIMEOUT_US 100000
+/* Sleep should be less than 20ms */
+#define RK_PHY_PLL_LOCK_SLEEP_US 1000
+
 int rockchip_pcie_init_port(struct rockchip_pcie *rockchip)
 {
 	struct device *dev = rockchip->dev;
@@ -254,6 +261,16 @@ int rockchip_pcie_init_port(struct rockchip_pcie *rockchip)
 		}
 	}
 
+	err = readx_poll_timeout(rockchip_pcie_read_addr,
+				 PCIE_CLIENT_SIDE_BAND_STATUS,
+				 regs, !(regs & PCIE_CLIENT_PHY_ST),
+				 RK_PHY_PLL_LOCK_SLEEP_US,
+				 RK_PHY_PLL_LOCK_TIMEOUT_US);
+	if (err) {
+		dev_err(dev, "PHY PLLs could not lock, %d\n", err);
+		goto err_power_off_phy;
+	}
+
 	/*
 	 * Please don't reorder the deassert sequence of the following
 	 * four reset pins.

drivers/pci/controller/pcie-rockchip.h

@@ -38,6 +38,8 @@
 #define   PCIE_CLIENT_MODE_EP            HIWORD_UPDATE(0x0040, 0)
 #define   PCIE_CLIENT_GEN_SEL_1		  HIWORD_UPDATE(0x0080, 0)
 #define   PCIE_CLIENT_GEN_SEL_2		  HIWORD_UPDATE_BIT(0x0080)
+#define PCIE_CLIENT_SIDE_BAND_STATUS	(PCIE_CLIENT_BASE + 0x20)
+#define   PCIE_CLIENT_PHY_ST			BIT(12)
 #define PCIE_CLIENT_DEBUG_OUT_0		(PCIE_CLIENT_BASE + 0x3c)
 #define   PCIE_CLIENT_DEBUG_LTSSM_MASK		GENMASK(5, 0)
 #define   PCIE_CLIENT_DEBUG_LTSSM_L1		0x18