[d-kernel] [PATCH 4/5] pci: baikal-pcie: use raw_spinlock for regmap of gbr registers

[Daniil Gnusarev <gnusarevda@basealt.ru>]

With the kasan debug options enabled, the following errors are observed
in the kernel log:

[    4.564453] =============================
[    4.568951] [ BUG: Invalid wait context ]
[    4.573451] 6.6.71+ #16 Not tainted
[    4.577368] -----------------------------
[    4.581864] swapper/0/1 is trying to lock:
[    4.586461] ffff000801ef2018 (syscon:125:(&syscon_config)->lock){....}-{3:3}, at: regmap_lock_spinlock+0x20/0x48
[    4.597931] other info that might help us debug this:
[    4.603599] context-{5:5}
[    4.606539] 2 locks held by swapper/0/1:
[    4.610943]  #0: ffff0008019000f8 (&dev->mutex){....}-{4:4}, at: __driver_attach+0x154/0x308
[    4.620459]  #1: ffff8000841911f8 (pci_lock){....}-{2:2}, at: pci_bus_read_config_dword+0xac/0x160
[    4.630558] stack backtrace:
[    4.633793] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 6.6.71+ #16
[    4.640634] Hardware name: Edelweiss TF307-MB-S-D/BM1BM1-D, BIOS 5.6 07/26/2022
[    4.648836] Call trace:
[    4.651581]  dump_backtrace+0xa4/0x130
[    4.655796]  show_stack+0x20/0x38
[    4.659522]  dump_stack_lvl+0x60/0xb0
[    4.663638]  dump_stack+0x1c/0x28
[    4.667363]  __lock_acquire+0xd24/0x2da8
[    4.671775]  lock_acquire+0x308/0x470
[    4.675892]  _raw_spin_lock_irqsave+0x80/0xb8
[    4.680789]  regmap_lock_spinlock+0x20/0x48
[    4.685490]  regmap_read+0x64/0xc0
[    4.689314]  bm1000_pcie_link_up+0x118/0x1b8
[    4.694112]  dw_pcie_link_up+0x44/0x90
[    4.698324]  dw_pcie_other_conf_map_bus+0x44/0x110
[    4.703707]  pci_generic_config_read+0x5c/0xf8
[    4.708699]  dw_pcie_rd_other_conf+0x58/0xf8
[    4.713495]  pci_bus_read_config_dword+0xe0/0x160
[    4.718777]  pci_bus_generic_read_dev_vendor_id+0x3c/0x228
[    4.724939]  pci_scan_single_device+0x114/0x1c0
[    4.730029]  pci_scan_slot+0xdc/0x2c0
[    4.734144]  pci_scan_child_bus_extend+0x58/0x3b0
[    4.739429]  pci_scan_bridge_extend+0x1e8/0x890
[    4.744519]  pci_scan_child_bus_extend+0x158/0x3b0
[    4.749900]  pci_scan_root_bus_bridge+0xa8/0x150
[    4.755088]  pci_host_probe+0x20/0xf0
[    4.759203]  dw_pcie_host_init+0x3e8/0x9e8
[    4.763804]  bm1000_add_pcie_port+0x130/0x3d8
[    4.768698]  baikal_pcie_probe+0x140/0x198
[    4.773300]  platform_probe+0x94/0x150
[    4.777513]  really_probe+0x254/0x5b8
[    4.781627]  __driver_probe_device+0xcc/0x238
[    4.786520]  driver_probe_device+0x64/0x1b0
[    4.791219]  __driver_attach+0x160/0x308
[    4.795624]  bus_for_each_dev+0xe4/0x168
[    4.800035]  driver_attach+0x3c/0x58
[    4.804054]  bus_add_driver+0x188/0x310
[    4.808364]  driver_register+0xb0/0x1f8
[    4.812673]  __platform_driver_register+0x4c/0x68
[    4.817956]  baikal_pcie_driver_init+0x28/0x40
[    4.822951]  do_one_initcall+0xe0/0x4c8
[    4.827262]  kernel_init_freeable+0x394/0x500
[    4.832160]  kernel_init+0x38/0x230
[    4.836084]  ret_from_fork+0x10/0x20

Caused by attempting to take spinlock while raw_spinlock is held.
To fix, raw_spinlock is also used for regmap.

Signed-off-by: Daniil Gnusarev <gnusarevda@basealt.ru>
Do-not-upstream: this is a feature of Baikal-M
---
 drivers/pci/controller/dwc/pcie-baikal-core.c | 35 +++++++++++++++----
 1 file changed, 29 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-baikal-core.c b/drivers/pci/controller/dwc/pcie-baikal-core.c
index a1de90e0ef6e1..7f597b8a17f94 100644
--- a/drivers/pci/controller/dwc/pcie-baikal-core.c
+++ b/drivers/pci/controller/dwc/pcie-baikal-core.c
@@ -16,6 +16,7 @@
 #include <linux/of_device.h>
 #include <linux/pci.h>
 #include <linux/pci-ecam.h>
+#include <linux/of_address.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 
@@ -188,19 +189,39 @@ static int bm1000_get_resources(struct platform_device *pdev,
 	struct bm1000_pcie *bm = platform_get_drvdata(pdev);
 	struct device *dev = pci->dev;
 	struct resource *res;
+	void __iomem *gpr_base;
+	struct device_node *gpr_syscon_node;
 
 	bm->pci = pci;
 	bm->gpr_offset = 0;
-	bm->gpr = syscon_regmap_lookup_by_compatible("baikal,bm1000-pcie-gpr");
-	if (IS_ERR(bm->gpr)) {
+	gpr_syscon_node = of_find_compatible_node(NULL, NULL, "baikal,bm1000-pcie-gpr");
+	if (!gpr_syscon_node) {
 		dev_warn(dev, "failed to find PCIe GPR registers, trying LCRU\n");
-		bm->gpr = syscon_regmap_lookup_by_phandle(dev->of_node, "baikal,pcie-lcru");
-		if (IS_ERR(bm->gpr)) {
+		gpr_syscon_node = of_parse_phandle(dev->of_node, "baikal,pcie-lcru", 0);
+		if (!gpr_syscon_node) {
 			dev_err(dev, "failed to find PCIe LCRU registers\n");
-			return PTR_ERR(bm->gpr);
+			return -EINVAL;
 		}
 		bm->gpr_offset = BM1000_PCIE_GPR_OFFSET;
 	}
+	if (!of_device_is_compatible(gpr_syscon_node, "syscon")) {
+		dev_err(dev, "failed to find PCIe GPR registers\n");
+		of_node_put(gpr_syscon_node);
+		return -EINVAL;
+	}
+
+	gpr_base = of_iomap(gpr_syscon_node, 0);
+	of_node_put(gpr_syscon_node);
+	if (!gpr_base) {
+		dev_err(dev, "failed to remap PCIe GPR registers\n");
+		return -EINVAL;
+	}
+
+	bm->gpr = devm_regmap_init_mmio(dev, gpr_base, &bm1000_pcie_syscon_regmap_config);
+	if (IS_ERR(bm->gpr)) {
+		dev_err(dev, "failed to init regmap for PCIe GPR registers\n");
+		return PTR_ERR(bm->gpr);
+	}
 
 	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dbi");
 	if (!res) {
@@ -1117,7 +1138,9 @@ static struct regmap *bm1000_regmap;
 static const struct regmap_config bm1000_pcie_syscon_regmap_config = {
 	.reg_bits = 32,
 	.val_bits = 32,
-	.reg_stride = 4
+	.reg_stride = 4,
+	.fast_io = true,
+	.use_raw_spinlock = true,
 };
 
 static struct regmap *bm1000_pcie_get_gpr_acpi(struct bm1000_pcie *bm)
-- 
2.42.2