1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/pci-ecam.h>
3 #include <linux/delay.h>
4 #include <linux/of.h>
5
6 #define SMP8759_MUX 0x48
7 #define SMP8759_TEST_OUT 0x74
8
9 struct tango_pcie {
10 void __iomem *base;
11 };
12
smp8759_config_read(struct pci_bus * bus,unsigned int devfn,int where,int size,u32 * val)13 static int smp8759_config_read(struct pci_bus *bus, unsigned int devfn,
14 int where, int size, u32 *val)
15 {
16 struct pci_config_window *cfg = bus->sysdata;
17 struct tango_pcie *pcie = dev_get_drvdata(cfg->parent);
18 int ret;
19
20 /* Reads in configuration space outside devfn 0 return garbage */
21 if (devfn != 0)
22 return PCIBIOS_FUNC_NOT_SUPPORTED;
23
24 /*
25 * PCI config and MMIO accesses are muxed. Linux doesn't have a
26 * mutual exclusion mechanism for config vs. MMIO accesses, so
27 * concurrent accesses may cause corruption.
28 */
29 writel_relaxed(1, pcie->base + SMP8759_MUX);
30 ret = pci_generic_config_read(bus, devfn, where, size, val);
31 writel_relaxed(0, pcie->base + SMP8759_MUX);
32
33 return ret;
34 }
35
smp8759_config_write(struct pci_bus * bus,unsigned int devfn,int where,int size,u32 val)36 static int smp8759_config_write(struct pci_bus *bus, unsigned int devfn,
37 int where, int size, u32 val)
38 {
39 struct pci_config_window *cfg = bus->sysdata;
40 struct tango_pcie *pcie = dev_get_drvdata(cfg->parent);
41 int ret;
42
43 writel_relaxed(1, pcie->base + SMP8759_MUX);
44 ret = pci_generic_config_write(bus, devfn, where, size, val);
45 writel_relaxed(0, pcie->base + SMP8759_MUX);
46
47 return ret;
48 }
49
50 static struct pci_ecam_ops smp8759_ecam_ops = {
51 .bus_shift = 20,
52 .pci_ops = {
53 .map_bus = pci_ecam_map_bus,
54 .read = smp8759_config_read,
55 .write = smp8759_config_write,
56 }
57 };
58
tango_pcie_link_up(struct tango_pcie * pcie)59 static int tango_pcie_link_up(struct tango_pcie *pcie)
60 {
61 void __iomem *test_out = pcie->base + SMP8759_TEST_OUT;
62 int i;
63
64 writel_relaxed(16, test_out);
65 for (i = 0; i < 10; ++i) {
66 u32 ltssm_state = readl_relaxed(test_out) >> 8;
67 if ((ltssm_state & 0x1f) == 0xf) /* L0 */
68 return 1;
69 usleep_range(3000, 4000);
70 }
71
72 return 0;
73 }
74
tango_pcie_probe(struct platform_device * pdev)75 static int tango_pcie_probe(struct platform_device *pdev)
76 {
77 struct device *dev = &pdev->dev;
78 struct tango_pcie *pcie;
79 struct resource *res;
80 int ret;
81
82 dev_warn(dev, "simultaneous PCI config and MMIO accesses may cause data corruption\n");
83 add_taint(TAINT_CRAP, LOCKDEP_STILL_OK);
84
85 pcie = devm_kzalloc(dev, sizeof(*pcie), GFP_KERNEL);
86 if (!pcie)
87 return -ENOMEM;
88
89 res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
90 pcie->base = devm_ioremap_resource(dev, res);
91 if (IS_ERR(pcie->base))
92 return PTR_ERR(pcie->base);
93
94 platform_set_drvdata(pdev, pcie);
95
96 if (!tango_pcie_link_up(pcie))
97 return -ENODEV;
98
99 return pci_host_common_probe(pdev, &smp8759_ecam_ops);
100 }
101
102 static const struct of_device_id tango_pcie_ids[] = {
103 { .compatible = "sigma,smp8759-pcie" },
104 { },
105 };
106
107 static struct platform_driver tango_pcie_driver = {
108 .probe = tango_pcie_probe,
109 .driver = {
110 .name = KBUILD_MODNAME,
111 .of_match_table = tango_pcie_ids,
112 .suppress_bind_attrs = true,
113 },
114 };
115 builtin_platform_driver(tango_pcie_driver);
116
117 /*
118 * The root complex advertises the wrong device class.
119 * Header Type 1 is for PCI-to-PCI bridges.
120 */
tango_fixup_class(struct pci_dev * dev)121 static void tango_fixup_class(struct pci_dev *dev)
122 {
123 dev->class = PCI_CLASS_BRIDGE_PCI << 8;
124 }
125 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0024, tango_fixup_class);
126 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0028, tango_fixup_class);
127
128 /*
129 * The root complex exposes a "fake" BAR, which is used to filter
130 * bus-to-system accesses. Only accesses within the range defined by this
131 * BAR are forwarded to the host, others are ignored.
132 *
133 * By default, the DMA framework expects an identity mapping, and DRAM0 is
134 * mapped at 0x80000000.
135 */
tango_fixup_bar(struct pci_dev * dev)136 static void tango_fixup_bar(struct pci_dev *dev)
137 {
138 dev->non_compliant_bars = true;
139 pci_write_config_dword(dev, PCI_BASE_ADDRESS_0, 0x80000000);
140 }
141 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0024, tango_fixup_bar);
142 DECLARE_PCI_FIXUP_EARLY(PCI_VENDOR_ID_SIGMA, 0x0028, tango_fixup_bar);
143